Patent Publication Number: US-7585277-B2

Title: Surgical instruments and procedures for stabilizing the beating heart during coronary artery bypass graft surgery

Description:
CROSS-REFERENCE 
   This application is a continuation of U.S. application Ser. No. 10/100,314, filed on Mar. 14, 2002 now U.S. Pat. No. 7,056,287; which is a continuation of U.S. application Ser. No. 09/525,774 filed on Mar. 13, 2000, now U.S. Pat. No. 6,394,951; which is a divisional of U.S. application Ser. No. 08/931,158 filed Sep. 16, 1997, now U.S. Pat. No. 6,036,641; which is a continuation-in-part of U.S. application Ser. No. 08/789,751, filed Jan. 27, 1997, now U.S. Pat. No. 6,346,077; which is a continuation-in-part of U.S. application Ser. No. 08/603,758, filed Feb. 20, 1996, now U.S. Pat. No. 5,894,843. U.S. application Ser. No. 10/100,314 and U.S. Pat. Nos. 6,394,951; 6,036,641; 6,346,077 and 5,894,843 are hereby incorporated by reference thereto, in their entireties. 

   BACKGROUND OF THE INVENTION 
   Diseases of the cardiovascular system affect millions of people each year and are a leading cause of death throughout the world. The costs to society from such diseases is enormous both in terms of the lives lost and in terms of the cost of treating patients through traditional surgical techniques. A particularly prevalent form of cardiovascular disease is a reduction in the blood supply leading to the heart caused by atherosclerosis or other condition that creates a restriction in blood flow at a critical point in the cardiovascular system that supplies blood to the heart. In many cases, such a blockage or restriction in the blood flow leading to the heart is treated by a surgical procedure known as a Coronary Artery Bypass Graft (CABG) procedure, more commonly known as a “heart bypass” operation. In the CABG procedure, the surgeon “bypasses” the obstruction to restore normal blood flow to the heart by attaching an available source vessel to an obstructed target coronary artery or by removing a portion of a vein or artery from another part of the body, to use as a graft, and by installing the graft at points between a source vessel and a target artery to restore normal blood flow. 
   Although the CABG procedure has become relatively common, the procedure itself is lengthy and traumatic and can damage the heart, the cardiovascular system, the central nervous system, and the blood supply itself. In a conventional CABG procedure, the surgeon must make a long incision down the center of the chest, cut through the entire length of the sternum, perform several other procedures necessary to attach the patient to a heart-lung bypass machine, cut off the blood flow to the heart, and then stop the heart from beating in order to complete the bypass. The most lengthy and traumatic surgical procedures are necessary, in part, to connect the patient to a cardiopulmonary bypass (CPB) machine to continue the circulation of oxygenated blood to the rest of the body while the bypass is completed. 
   Although several efforts have been made to make the CABG procedure less invasive and less traumatic, most techniques still require cardiopulmonary bypass (CPB) and cardioplegia (stopping the heart). The safety and efficacy of the CABG procedure could be improved if the surgeon could avoid the need to stop the heart from beating during the procedure, thereby eliminating cardiopulmonary bypass and the lengthy and traumatic surgical procedures necessary to connect the patient to a cardiopulmonary bypass machine to sustain the patient&#39;s life during the procedure. In recent years, a small number of surgeons have begun performing CABG procedures using surgical techniques especially developed so that the CABG procedure could be performed while the heart is still beating. In such procedures, there is no need for any form of cardiopulmonary bypass, no need to perform the extensive surgical procedures necessary to connect the patient to a cardiopulmonary bypass machine, and no need to stop the heart. As a result, the surgery is much less invasive and the entire procedure can typically be achieved through a small number, typically one or two, comparatively small incisions in the chest. 
   Despite the advantages, the beating-heart CABG procedure is not widely practiced, in part, because of the difficulty in performing the necessary surgical procedures using conventional surgical instruments. If specially designed instruments were available so that the CABG procedure could be performed on the beating heart, the beating-heart CABG procedure would be more widely practiced and the treatment of cardiovascular disease in a significant patient population would be improved. 
   As noted above, the CABG procedure requires a fluid connection for restoring the flow of blood be established between two points to “bypass” a diseased or obstructed area to restore blood flow to the heart. This procedure is known as an “anastomosis.” Typically, a source vessel, such as a source artery with an unobstructed blood flow, i.e., the left internal mammary artery (LIMA), or a bypass-graft having one end sewn to an unobstructed blood source such as the aorta, is sewn to a target occluded coronary artery, such as the left anterior descending (LAD) artery or other vessel, that provides blood flow to the muscles of the heart. Because the beating-heart CABG procedure is performed while the heart muscle is continuing to contract and pump blood, the anastomosis procedure is difficult to perform because the heart continues to move while the surgeon is sewing the anastomosis. 
   The specific part of the surgical procedure that creates the anastomosis in the beating-heart CABG procedure requires placing a series of sutures through extremely small vessels on the surface of the heart and requires completing the anastomosis while the heart muscle continues to beat to pump blood during the procedure. Moreover, the sutures must be carefully placed so that the source vessel or graft is firmly attached when the anastomosis is complete and does not leak when blood flow through the vessel is established. It is also important that the anastomosis procedure be performed rapidly because the blood flow through the target coronary artery may be temporarily interrupted or reduced to avoid excessive blood loss. Also, the working space and visual access are limited because the surgeon may be working through a small incision in the chest or may be viewing the procedure on a video monitor if the site of the surgery is viewed via a surgical scope. 
   In one current practice, the surgeon places sutures through the heart tissue and, by exerting opposing tension on the sutures, stretches the tissue surrounding the site of the anastomosis to partially reduce the motion of the heart while the anastomosis is completed. This approach is far from ideal. Alternatively, a suction device may be attached to the surface of the heart to fix the motion of the outer layer of surface tissue. In such cases, a suction device typically has several ports incorporated into an instrument that may be attached to the heart to apply a negative pressure to the surface tissue. The negative pressure essentially attaches the surface tissue to the apparatus thereby fixing the position of a portion of the surface of the heart. Such devices are described in U.S. Pat. No. 5,727,569. 
   While the negative pressure approach may be effective in fixing a portion of the surface tissue of the heart, the negative pressure applied to cardiac tissue can result in temporary hematomas at the site where the suction ports attach to the tissue. Also, the exterior cardiac tissue is fixed in a configuration defined by the shape of the instrument and the orientation of the suction ports. While the heart continues to beat, the heart muscles are contracting to pump blood, which results in the muscles exerting a force directed away from the exterior tissue fixed by suction. 
   The beating-heart CABG procedure could be greatly improved if the heart could be stabilized during the procedure such that the motion of the heart, particularly at the site of the anastomosis, is minimized even though the heart continues to beat to supply blood to the body. If effective means for stabilizing the beating heart were available, the beating-heart CABG procedure could be performed more easily, more rapidly, more safely, and with less trauma to the patient. 
   SUMMARY OF INVENTION 
   The advantages provided to a surgeon by the instruments and techniques of the invention allow the beating heart CABG procedure to be performed more rapidly, with less trauma to the patient, and enable a surgeon to perform a CABG procedure without CPB or cardioplegia. This invention provides an alternative approach to a suction apparatus by providing devices and methods for stabilizing the motion of the heart using mechanical instruments specially designed to apply a stabilizing force to the heart to minimize the motion of the beating heart during a surgical procedure. The invention enables a surgeon to readily and rapidly perform a beating-heart CABG procedure thus avoiding the need for cardioplegia or cardiopulmonary bypass. In particular, the methods and devices described herein enable the surgeon to stabilize the heart such that an anastomosis can be more readily accomplished by enabling the surgeon to attach a source vessel or bypass graft to a target coronary artery whose motion is minimized for the duration of the surgical procedure. 
   Pursuant to the invention, a stabilizing device is introduced through a suitable opening in the chest that provides access to the beating heart. By contacting the heart with the means for stabilizing the beating heart of this invention, and by exerting a stabilizing force on the heart, the motion of the heart caused by the contraction of the heart muscles is effectively eliminated such that movement of the target artery at the site of the anastomosis is minimized. The remainder of the heart may be allowed to contract normally or may have additional devices in place to support the heart or to restrain its motion. Additionally, several of the devices of the invention may be used to position the beating heart to provide an improved surgical field, to maintain the heart in a preferred configuration for surgery, or to rotate the heart to present distinct features of the heart to the surgeon&#39;s visible and accessible surgical field. 
   An important advantage of this invention is derived from the discovery that a new and effective technique can be described herein and performed in surgery using the devices of the invention to provide an advantageous technique for stabilizing or positioning the beating heart during a surgical procedure. The procedure for stabilizing the beating heart generally requires exerting a stabilizing force on the beating heart using devices constructed as described herein. Typically, in separate steps, the surgeon contacts the heart with at least one component of the means for stabilizing the beating heart of this invention, assesses the degree of movement of the heart, particularly at the site of the surgery, and positions the component of the stabilizing means proximate to the site of the surgery such as a target coronary artery of an anastomosis. With the functional portion of a stabilizing means in place, the surgeon applies a stabilizing force to the beating heart such that the portion of the instrument in contact with the surface of the heart displaces the surface of the heart a sufficient distance that the contraction of the heart does not cause substantial motion, either vertical or horizontal, at the surgery site. The stabilizing force is applied directly or indirectly using at least one component of the stabilizing means of the invention and is comprised of exerting a mechanical force onto the beating heart, generally at a specific location such as a target coronary artery and generally exerting force that is at least partially applied in a direction perpendicular to the surface of the beating heart. Thus, an important aspect of this invention is the discovery that the beating heart may be effectively stabilized for the purpose of a surgical procedure by using a specially designed instrument as described herein to exert a mechanical stabilizing force on the exterior of the heart, particularly where the force is exerted proximate to the site of the surgery. The stabilizing force may consist of a force that resists the motion supplied by the beating heart, or additional forces applied to the heart, or the stabilizing force. 
   By fixing the position of the stabilizing means in a configuration where the motion of the beating heart is effectively eliminated, the surgeon maintains the stabilizing force on the beating heart for the duration of the procedure. To fix the position of the means for stabilizing the beating heart, the stabilizing means may be attached to a retractor used to separate the ribs or to another fixed support. The stabilizing means may also be attached to a conformable, flexible, or semi-rigid arm or shaft means which is rendered substantially rigid mechanically, chemically, or by human intervention. In certain preferred embodiments, the stabilizing means has an adjustable shaft means which may be oriented in several directions and has a fixture adapted to be attached to a retractor. In a preferred technique of the invention, the surgeon first performs a thoracotomy and retracts the ribs using a retractor, which may then be locked in an open position providing access to the beating-heart. The surgeon then contacts the surface of the heart with a component of the stabilizing means, which has been provided with an adjustable shaft, at a point proximate to the target coronary artery, and exerts a stabilizing force on the means for stabilizing the beating heart. By manipulating the adjustable shaft, the site of the surgery will become substantially motionless. This force may be advantageously applied, and the absolute amount of force minimized with the additional feature of an adhesive or high friction surface on the component of the stabilizing means that contacts the beating heart. At this point, the adjustable shaft means is fixed in position, for example by being stably attached to the retractor, thereby rendering the target coronary artery substantially motionless for the duration of the procedure. 

   
     DESCRIPTION OF THE FIGURES 
       FIG. 1  is a means for stabilizing the beating heart having a pair of substantially planar contact members which are oriented to engage the heart proximate to the site at which a bypass will be sewn.  FIG. 1  also shows the contact members attached to a shaft means which may be adjustable in several directions and which may be attached to a retractor or other fixed support structure.  FIG. 1A  is a detail of the shaft means and the structure of the adjustable positioning mechanisms.  FIGS. 1B through 1G  are various configurations of a contact member having a friction means which is preferably affixed to the bottom surface of the contact member. 
       FIG. 2  is an example of a snap-on member affixed to the bottom surface of a contact member for ease of manufacture and disposability advantages. 
       FIG. 3  is an example of a stabilizing means of the invention having an inflatable or fluid-filled cushioning member disposed between the bottom surface of the contact member and the surface of the beating heart. 
       FIGS. 4A through 4C  show an embodiment of the invention having weighted contact members that engage the beating heart, and which may be part of a system to achieve stabilization of the heart by applying a stabilizing force via a balanced mass having an adjustable weight and counterweight configuration.  FIG. 4A  shows the weighted contact member in cross section.  FIG. 4B  is the contact members having an opening disposed therebetween for positioning of a vessel.  FIG. 4C  shows the contact member coupled to a shaft that is affixed to a fulcrum having an adjustable weight and a counter-weight. 
       FIG. 5  shows an embodiment of the invention having a counter-contact member positioned opposite a pair of contact member and having a shaft positioned at an intermediate point therebetween. 
       FIGS. 6A and 6B  show embodiments of the invention having contact members which have a conformable shape, and where a flexible or semi-rigid member may be passed through the body of the contact member. 
       FIG. 7A  shows an embodiment of the contact member wherein the contact member has ports for releasable attachment of the distal end of a shaft means.  FIG. 7B  shows an embodiment wherein a plurality of ports are disposed about the periphery of a contact member for releasable attachment to the distal end of a shaft means.  FIG. 7C  shows an embodiment of the invention wherein a separate shaft is provided having distal portions adapted to fit within ports on a contact member.  FIGS. 7D and 7E  show an embodiment of the invention wherein the contact members are formed from the distal portion of a shaft means for minimally invasive applications.  FIG. 7E  shows an interconnecting member for joining the distal portions of the shaft means. 
       FIG. 8  shows an embodiment of the invention having a substantially annular contact member which is affixed to a shaft which is rotatable about the annular contact member and which may be locked into position at a given point about the periphery of the contact member. 
       FIGS. 9A through 9G  show embodiments of the invention where a positive or negative pressure is provided proximate to the contact members.  FIG. 9H  shows an embodiment of the invention where a light source is provided to illuminate the area where the beating heart is contacted by the contact members. 
       FIGS. 10A through 10C  show embodiments of the invention where a surgical drape is operably associated with the contact members to provide an isolated visual field. 
       FIG. 11  shows the contact members of the invention associated with an apparatus to facilitate completing the anastomosis. 
       FIG. 12  shows an embodiment of the invention where the shaft means has associated therewith a separate vessel holder. 
       FIGS. 13A through 13E  show a cannula assembly preferred for providing minimally invasive access for the stabilizing means of the invention.  FIG. 13A  has screws for attaching the cannula assembly to the chest wall.  FIG. 13B  has a threaded portion about the periphery of the cannula.  FIGS. 13C through 13E  show a locking mechanism designed to engage adjacent ribs. 
       FIG. 14  shows a conical cannula having a smaller distal end to engage the surface of the beating heart and a larger proximal opening for introducing surgical instruments to the beating heart. 
       FIGS. 15A and 15B  show an embodiment of the invention inserted through the chest wall in a minimally invasive fashion via a cannula to bring the contact members into engagement with the beating heart. 
       FIGS. 16A through 16E  show an embodiment of the invention designed for minimally invasive insertion and removal of flexible contact members whereby the contact members are maintained in a retracted state within a hollow portion of a shaft and are deployed upon extension of a central shaft. 
       FIGS. 17A through 17D  show an additional embodiment providing minimally invasive insertion and removal of the contact members of the invention whereby individual contact members are rotated into position by a hinge at the distal end of a shaft. 
       FIGS. 18A through 18D  show contact members which are attached to a guide that is positioned about a shaft such that downward movement of the guide causes the contact members to be deployed. 
       FIGS. 19A and 19B  show contact members of the invention attached to a shaft means by a plurality of struts that extend the contact members into position. 
       FIGS. 20A through 20E  show contact members of the invention that are rotatable about the distal portion of a shaft means by a plurality of hinges. 
       FIGS. 21A through 21C  show an embodiment having contact members formed from a unitary wire which is looped such that when extended from a body of the device, the contact members are deployed, and may be removed in a minimally invasive fashion by withdrawing a portion of the wire into the body of the device. 
       FIGS. 22A through 22C  show an embodiment of the invention wherein the contact members are formed from a helical coil which may be withdrawn into the hollow portion of a shaft for minimally invasive insertion and removal. 
       FIGS. 23A and 23B  show inflatable contact members that may be deflated for insertion or removal by being drawn into the body of a shaft. 
       FIGS. 24A and 24B  show a contact member of the invention formed from an inflatable annular cuff. 
       FIGS. 25A and 25B  show contact members formed from the divided portion of the distal end of a shaft. 
       FIGS. 26A through 26C  show contact members having sutures associated therewith for manipulation of a target artery. 
       FIGS. 27A and 27B  show an intravessel stabilizer adapted to fit within the target coronary artery. 
       FIGS. 28A and 28B  show contact members of the invention having means associated therewith for positioning epicardial tissue. 
       FIGS. 29A and 29B  show contact members of the invention having rotatable cylindrical rollers for collecting or spreading epicardial tissue proximate to a target artery. 
       FIG. 30  shows a means for stabilizing the beating heart having a pair of contact members which are additionally comprised of a spring-tensioned frame having an extension that engages and spreads the tissue at the site of the surgery to better expose the coronary artery. 
       FIGS. 31A and 31B  show embodiments of the stabilizing means having a single shaft means associated with each contact member and where the shaft means are interconnected and can be moved independently about a pivot such that the contact members spread the surface tissue of the heart proximate to the target coronary artery to increase exposure of the target artery at the site of the anastomosis. 
       FIGS. 32A through 32C  show embodiments of the invention wherein the contact members have additional structures associated therewith for retraction of epicardial tissue, the epicardial retractors may be comprised of pins which extend from the bottom surface of the contact member. 
       FIGS. 33A and 33B  show means for stabilizing the beating heart comprising a system which incorporates the retractor which spreads the ribs to provide surgical access to the heart. The stabilizing means is comprised of a pair of stabilizing plates which may be used together with a lever device to improve exposure of the target coronary artery. 
       FIGS. 34A through 34D  show an embodiment of the invention having a lockable mechanism for depressing epicardial tissue on either side of a target coronary artery. 
       FIG. 35  shows a substantially planar stabilizing platform which contacts the heart at a site proximate to and surrounding the coronary vessel. The platform may also have associated therewith at least one occluder which restricts or eliminates blood flow through an artery and an associated device for spreading the tissue proximate to the anastomosis. 
       FIG. 36  shows an artery occluder comprised of a shaft portion and having a blunt portion to engage a target artery. 
       FIGS. 37A through 37C  show contact members having structures associated therewith for occluding the target coronary artery. 
       FIGS. 38A and 38B  show contact members of the invention having a flange associated therewith for use with sutures that surround the target vessel and may be used in connection with a movable shaft or suture guide to occlude the target vessel. 
       FIG. 39  shows an embodiment of the contact member of the invention having one or more fixtures attached, preferably to a planar surface thereof, and adapted to receive a surgical tool or accessory such as scissors, forceps, or surgical needles for the convenience of the surgeon during the anastomosis procedure. 
       FIG. 40  shows an embodiment of the invention having flex joints between the contact members, the interconnecting shaft, or the shaft means to provide continuous positioning of the contact members. 
       FIG. 41  shows an embodiment of the invention having lockable joints associated with the shaft means. 
       FIG. 42  shows a flexible, lockable arm which allows positioning in every direction to place and orient the contact members until the requisite degree of stabilization is achieved at which point the arm having a stabilizing means is fixed in position. The flexible, lockable arm may be attached to a retractor and is caused to become rigid when the entire stabilizing means is properly positioned. 
       FIG. 43  shows a conformable, lockable arm having hollow cylinders and spheres and an inflatable balloon member disposed therein to lock the arm into position. 
       FIGS. 44A and 44B  show embodiments of the invention having curved interlocking segments wherein teeth formed at the interconnecting surfaces of each segment prevent rotation of the respective segments. 
       FIGS. 45A and 45B  show a flexible shaft having means incorporated therein for fixing the position of the shaft. 
       FIGS. 46A through 46C  show an embodiment of the invention where a series of adjustable links have an a elastomeric hydraulic medium disposed therein and where application of force causes the elastomeric hydraulic medium to become rigid and fixes the position of the adjustable links. 
       FIG. 47  shows an embodiment of the invention having a flexible shaft with a plurality of strands located therein wherein locking the strands in position at a distal portion causes the shaft to become rigid. 
       FIG. 48  shows a flexible shaft having a plurality of lumens disposed therein such that sealing of the lumens fixes the position of the flexible shaft. 
       FIG. 49  shows a fine adjusting mechanism wherein a plurality of threaded cables are attached to a proximal portion of a shaft means whereby turning the threaded cables causes the proximal portion of the shaft means to be adjusted. 
       FIGS. 50A and 50B  show embodiments of the shaft means having spring-loaded or air-damping mechanisms to restrict the vertical motion of the shaft relative to a stable support. 
       FIGS. 51A and 51B  show shaft means of the invention provided with fine adjustment mechanisms for vertical positioning of the shaft. 
       FIG. 52  shows a malleable shaft that is mounted on a fixture attached to a retractor blade and having a handle for vertical positioning of the shaft. 
       FIG. 53  shows a shaft means comprised of an adjustable arm formed from several interlocking segments attached to a cable. 
       FIGS. 54A through 54C  show an adjustable shaft means of the invention wherein the position of the contact members are adjusted by a positioning handle located at the proximal portion of the shaft means and connected to a ball joint at the distal portion by a plurality of positioning wires. 
       FIG. 55A  shows an embodiment of the stabilizing means of the invention having stabilizer bars suspended from the bottom side of a rib retractor wherein the stabilizer bars engage a ratchet means.  FIG. 55B  has malleable shafts attached to a retractor and to the contact members. 
       FIGS. 56A through 56D  show a shaft means of the invention having mechanisms for adjustable positioning of the shaft relative to a stable support. 
       FIG. 57  shows an adjustable arm for attaching a shaft means of the invention to a stable support wherein the shaft means passes through a ball joint that is adjustable by a fixture on the arm and wherein the arm is locked in place on the stable support by a latch mechanism. 
       FIGS. 58A through 58C  show embodiments of the shaft means of the invention for adjustable positioning of the shaft means relative to a retractor blade. 
       FIGS. 59A through 59C  show adjustable shaft means of the invention that extend from a retractor blade or a retractor arm and are continuously positioned relative to the retractor blade or retractor arm. 
       FIG. 60  shows an embodiment having a central shaft with a handle at the proximal end that is positioned by a plurality of shaft guides which are preferably attached to an interconnecting arm affixed to a retractor. 
       FIG. 61  shows an embodiment of the stabilizing meads of the invention having a pair of plates operably associated with a rib retractor and a sphere disposed between the plates to facilitate orientation of the shaft means. 
       FIG. 62  shows an embodiment of the invention having a shaft means comprised of an arm which extends from the interconnecting bar of a retractor to a position below the retractor blades and has a substantially horizontal shaft. 
       FIG. 63  shows means for stabilizing the beating heart of the invention operably associated with a rib locking mechanism. 
       FIG. 64  shows stabilizing means of the invention adapted to be used as a means for positioning the beating heart, wherein the means are operably associated with a rib locking mechanism. 
       FIGS. 65A through 65D  show embodiments of the invention where the shaft means is comprised of a unitary hollow shaft. 
       FIG. 66  shows a means for stabilizing the beating heart having a sheath member with several pliable support attachments associated therewith which may include or be comprised of inflatable members which are positioned at one or several locations surrounding the heart and may have a lumen disposed within the sheath member for the introduction of air or a biocompatible fluid. 
       FIG. 67  shows a stabilizing means formed from a movable sheath member that is attached at either end to cranks mounted on the arms of a retractor. 
       FIGS. 68A through 68C  show a device for advantageous positioning of the heart comprised of a flexible sheet, preferably having a hydrogel coating on one side. 
       FIG. 69  shows an embodiment of the invention comprised of a plurality of telescoping shafts having the contact member affixed at their distal end and wherein the position of the telescoping shaft is manipulated and fixed by a hydraulic actuator. 
       FIG. 70A through 70D  show an embodiment of the invention having a conformable arm comprised of a plurality of friction joints that are engaged when the motion of the beating heart presses against the contact member. 
       FIGS. 71A through 71D  show an embodiment of the invention having a contractible shaft attached to a flexible slide. The flexible slide is designed to be inserted into a seed-shaped clip which may be attached to a retractor blade. The contractible shaft is extended to engage the beating heart by application of hydraulic pressure, for example, by a syringe that is preferably supplied with a one-way releasable valve. 
       FIG. 72  is a view of the interior of the chest cavity during a CABG procedure on the beating heart with the stabilizing means operably associated with a retractor and being used in conjunction with other surgical apparatus to facilitate completing the anastomosis. 
       FIGS. 73 and 74  show the stabilizing means of the invention having been introduced through a thoracotmy to contact the beating heart to engage the heart tissue on either side of a target coronary artery to which an anastomosis is sewn. 
       FIG. 75  shows an embodiment of the invention having a pair of shaft means operably associated with ball joints that are affixed to opposing arms of a retractor. 
       FIG. 76  shows a further embodiment of the invention including means for stabilizing the beating heart and a quick-locking base/shaft lock mechanism for solid attachment of the stabilizing means to a stable platform. 
       FIG. 77  shows an exploded perspective view of the stabilizing means of  FIG. 76 , including a shaft-locking support mechanism for maneuverably supporting a shaft means of the stabilizing means. 
       FIGS. 78 and 79  show perspective views of the top and bottom, respectively, of a base of  FIGS. 76 ,  77 . 
       FIG. 78A  shows a perspective view of one side of a pedestal means formed on a retractor arm. 
       FIG. 80  is a side view of the base of  FIGS. 76-79  locked to a retractor arm. 
       FIG. 81  is a cross-sectional view of the base and retractor arm taken along section line  81 - 81  of  FIG. 80 . 
       FIGS. 82 and 83  show side and top cross-sectional views respectively, of the shaft-locking support mechanism of  FIG. 77 . 
       FIGS. 82A and 82B  show a cross-sectional view taken along section line  82 A- 82 A of  FIG. 82 , and a bottom view of the shaft-locking support mechanism, respectively. 
       FIGS. 84 and 85  show side and top cross-sectional views of the shaft-locking mechanism employing an alternative shaft lock configuration. 
       FIG. 86  is a perspective view of the alternative shaft lock of  FIGS. 84 ,  85 . 
       FIGS. 87 and 88  show exploded perspective and cross-sectional views respectively of a handle mechanism of the stabilizing means. 
       FIG. 89  is an exploded perspective view of a contact member of the stabilizing means. 
       FIG. 90  is a rear view of the contact member of  FIGS. 76 ,  77  and  89 . 
       FIG. 91  is a cross-sectional view of the contact member of  FIG. 90  taken along section line  91 - 91 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   This invention is surgical instruments for stabilizing the beating heart and methods for their use. The means for stabilizing the beating heart are comprised of several alternative structures at least one component of which engages the surface of the heart to stabilize the beating heart during coronary surgery. The instruments provide the capability to exert and maintain a stabilizing force on the heart by contacting the heart with a component of the stabilizing means and by functionally fixing the position of the stabilizing means throughout the duration of a surgical procedure. 
   The instruments and methods of the invention are preferably used for stabilization of the beating heart during a minimally invasive coronary artery bypass graft (CABG) operation which has been specially developed to facilitate completion of an anastomosis, to a target coronary artery for example by the placement of a bypass graft or the connection of a source artery, without requiring cardiac arrest such as cardioplegia or fibrillation and without cardiopulmonary bypass (CPB). Although the means for stabilizing the beating heart can be applied in different surgical contexts, the devices described herein are most advantageously employed in a CABG procedure wherein only one or two minimally invasive incisions are placed in the chest. The complete structure of the stabilizing means of the invention may be provided by any of several structural embodiments which stabilize the beating heart while the minimally invasive surgical procedure is performed. Discrete components of the stabilizing means may also advantageously function in a multiple component system containing a retractor, an occluder, a surgical blower or suction device, an apparatus for holding the source artery, such as a LIMA holder, or other like discrete or integrated surgical devices or instruments that enable a surgeon to more efficiently complete the anastomosis. While the devices disclosed herein each use mechanical means to stabilize the beating heart, certain embodiments are designed to operate on the entire heart while others have a more localized effect and may be applied to the area immediately proximate to a structure such as the target artery of the anastomosis. In each instance, the beating heart is effectively stabilized at the area where a surgical procedure is to be performed. 
   Surgical access to the beating heart may be achieved by several conventional surgical procedures which have been developed for traditional cardiac bypass surgery and the surgeon may thereby obtain the advantages provided by this invention in any procedure where the bypass is achieved on the beating heart without regard to the surgical method or access to the heart. Preferably, the surgeon takes additional measures to restrict the movement of the entire heart within the chest cavity and may utilize certain embodiments disclosed herein to position or orient the beating heart. For example, an adjustable strap which may have inflatable cushions attached to the straps, or having laces may be inserted beneath or surrounding the heart. When access to the beating heart is achieved by a sternotomy, at least part of the length of the sternum is divided to expose the surface of the heart. Additionally, when the pericardium is available, the pericardium may be incised and used to position the beating heart. When available, the surgeon can use the pericardium to raise and rotate the beating heart within the chest cavity and maintain the position by suturing the pericardium to the periphery of the incision. 
   In a preferred embodiment, minimally invasive access to the beating heart is achieved by a thoracotomy, which is usually created in the left side of the chest by a smaller incision between the ribs, followed by insertion of a retractor between the ribs, spreading of the ribs, and securing the retractor in an open position to provide access to the source vessel and the target coronary artery. The use of the pericardium to position the beating heart as described above is particularly advantageous when the less invasive thoracotomy is used to provide access to the heart. In this procedure, an incision is created in the pericardium, which is then sutured to the periphery of the thoracotomy. In this configuration, the pericardium acts as a restraining sack to keep the beating heart in a desired orientation to achieve the anastomosis. 
   Once access to the heart is achieved, and the heart is positioned if necessary, the means for stabilizing the beating heart is introduced through the opening created by the thoracotomy and at least one component of the stabilizing device of the invention is brought into contact with the beating heart. The surgeon then applies a stabilizing force to the beating heart via the stabilizing means which may then be fixed in place by attachment to a fixed support. When the rib retractor or platform is fixed in an open position to expose the heart, the retractor platform may also provide the stable support structure to which the stabilizing means is affixed. When the position of the stabilizing means is fixed by attachment to a stable support or to the retractor platform, the stabilizing force is maintained for the duration of the procedure. 
   Although the particular source vessel and target artery of the anastomosis are determined clinically, a common minimally invasive bypass procedure on the beating heart includes an anastomosis which forms a connection between the left internal mammary artery (LIMA) as the source artery, and the left anterior descending artery (LAD) as the target artery. The LIMA to LAD anastomosis is used as an example herein but it is readily appreciated that the techniques and instruments described herein may be applied to other procedures depending on the clinical diagnosis and a patient&#39;s anatomy. To complete the anastomosis, the surgeon must dissect a portion of the LIMA by separating it from the internal chest cavity. Once dissection of the LIMA is achieved, the surgeon may attach the dissected LIMA to the target coronary artery, i.e., the LAD. In this example, the stabilizing means of this invention would be used to stabilize the beating heart during at least the portion of the procedure during which the surgeon completes the anastomosis of the LIMA to the LAD. 
   The structure of the portion of the stabilizing means which contacts the heart may include one or more contact members which exert a stabilizing force on the heart proximate to the site of the anastomosis. A pair of contact members may be plates or rectangular members which are placed on either side of the target coronary artery at the site of the anastomosis and which may have friction means or tissue spreading or compressing apparatus associated therewith. The contact members may also be provided by a platform which may be substantially planar or which may be contoured to fit conformingly on the surface of the heart. The stabilizing means may also include a shaft means having several alternative embodiments to facilitate adjusting the position and orientation of the instrument. For example, the shaft means may have an adjustable length and the axis of the shaft means may have at least one ball joint disposed within its length such that the orientation of the shaft means relative to another structure such as the contact members or stable support may be continuously varied. As is apparent from the description of the several embodiments, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the invention. 
   Referring to  FIG. 1 , a means for stabilizing the beating heart is comprised of one or more, and preferably two, contact members  1 , which are attached to a rigid, or semi-rigid connecting shaft  2  which is in turn connected to shaft means  3 . The contact members  1  may be substantially planar, may be slightly curved to conform to the shape of the heart, or may have a non-conforming curve to establish contact between only a portion of the contact member  1  and the beating heart. The contact members  1  may have any of several alternate shapes including cylindrical members, members formed into a U-shape, or may comprise a pair of substantially parallel members spaced apart in a parallel configuration such that a target artery can be positioned between the contact members. The shape of the contact members may be varied depending on the clinical assessment by the surgeon, the design of the other features of the stabilizing means, or the design of other instruments used to complete the anastomosis. In some embodiments, as described herein, the contact members  1  may have apertures, openings or attachments to facilitate connection with sutures or other devices to achieve the requisite stabilization, occlusion of the target vessel, or exposure of the target vessel. In a preferred embodiment, a pair of substantially planar rectangular contact members  1  are attached at one end to a continuous connecting shaft  2  and are oriented in a substantially parallel fashion such that a target cardiac artery is positioned therebetween and passes along the greater length of the contact members  1  when the stabilizing means engages the heart, see  FIGS. 72 through 74 . The connecting shaft  2  may be a continuous shaft for interconnection of the contact members  1  without touching the artery or may include an additional member which may be operated to contact the target artery positioned between the contact members  1 , see  FIGS. 36 through 38 , to occlude the passage of blood through the target artery. The contact members  1 , connecting shaft  2 , and shaft means  3  may be composed of any non-toxic material such as a biocompatible plastic or stainless steel, having sufficient tensile strength to withstand a stabilizing force exerted on the heart via manipulation or fixation of the shaft means  3  to cause the contact members  1  to exert a stabilizing force on the beating heart. Also, while the contact members  1  may each be connected to the connecting shaft  2  at one end, with the connecting shaft  2  operably attached to the shaft means  3 , each of the individual contact member embodiments described and illustrated herein has discrete features which may be readily separated from or combined with the features of any of the other several embodiments such as differing designs of the shaft means, or other components of the invention by one of ordinary skill in the art. 
   The shaft means  3  may be a simple rigid post or may be comprised of a multi-component system designed to be adjustable in length and orientation at at least one point along its length. Thus, the length of the shaft means  3  and the orientation of the contact members  1  at the distal (lower) end of the shaft means  3  can be altered by the surgeon. Preferably, the length and orientation at the shaft means  3  relative to the contact members  1  can be adjusted by controls located at the proximal (upper) end of shaft means  3 . (As used herein, the term “distal” refers to a portion of a device most proximal to the heart while the term proximal refers to the opposite portion which may extend outside of the incision and which is most often readily manipulated by the surgeon). This design provides the advantage that the surgeon can introduce the stabilizing means to the beating heart by placing the contact members  1  on the surface or the heart, followed by the combination of exerting a stabilizing force and locking the contact members  1  in place relative to the shaft means  3 . Furthermore, the surgeon may then lock the shaft means  3  into a fixed position by attachment to a stable support such as the retractor, thereby maintaining the stabilizing force for the duration of the procedure. In one embodiment, the shaft means  3  has a housing  1  whose overall length is adjustable by a telescoping release operated by an annular thumbscrew  8  which tightens about housing  11 . The position and orientation of the contact members  1  relative to the shaft means  3  is adjustable by virtue of a locking ball joint  5  which is interposed between the connecting shaft  2  and which is located at the distal end of shaft means  3 . The locking ball joint  5  allows the position of the shaft means  3  to be positioned with three degrees of freedom relative to the contact members  1 . 
   Referring again to  FIG. 1 , a locking ball joint  5  is provided by including a block  6  within the shaft means  3  which conformingly contacts the ball joint  5  and fixes the position of the ball joint  5 . Block  6  is compressed against ball joint  5  when a threaded push block  7 , connected to a long telescoping keyed shaft and socket combination  9 , is actuated by means such as a thumbscrew  8  at the upper end of the shaft means  3 . In operation, a rotation of the top thumbscrew  8  loosens the lower ball joint  5  to allow continuous positioning of the shaft means  3  relative to the contact members  1 , and a counter-rotation locks the ball joint  5  into place, fixing the position of the contact members  1  relative to shaft means  3 . 
   The upper end of shaft means  3  may also have associated therewith an upper ball joint  13  such that the shaft means  3  can be oriented with four degrees of freedom relative to a fixed support such as a retractor (not shown). The position and orientation of the shaft means  3  may thus be fixed relative to the stable support by a locking latch  14  or other conventional mechanism which prevents movement of the upper ball joint  13 . Either the shaft means  3  or the retractor may contain the locking latch  14  surrounding the upper ball joint  13  or any like fixture to firmly attach the shaft means  3  to a stable support, e.g., an anchor portion  15  extending from the retractor (not shown). 
   Referring to  FIGS. 1B through 1G , the contact members  1  preferably have friction means associated with their bottom surfaces  4  such that the contact members  1  more securely engage the beating heart when a stabilizing force is exerted on the shaft means  3 . The friction means are preferably comprised of a textured surface covering the bottom surface  4  of the contact member  1 , and may be comprised of several biocompatible substances such as a textured rubber, textured or ridged aluminum, stainless steel or the like. 
   The friction means may also be affixed to or comprised of a member disposed between the bottom surfaces  4  of the contact members  1  and the surface of the beating heart. In these embodiments, the friction means is provided to facilitate stabilization of the beating heart by maintaining close and conforming contact between the contact member  1  and the beating heart and reducing the amount of force necessary to be applied to the exterior of the beating heart in order to achieve stabilization. Referring to  FIGS. 1B and 1D  through  1 G, any number of different configurations may be employed to provide a textured surface, e.g., a diamond plate, granular, nail-bed, anti-skid, open foam, or other friction-providing configuration. The geometric configuration of the surface, having one side affixed to the contact member  1 , may be flat, triangular, rectangular, square, or circular. Alternatively, surfaces providing a functional adhesive may be obtained using hydrogel, fibrogen, collagen, hydroxy apatite, or other biocompatible material and may be chemically etched, mechanically scored, or electrically activated. 
   Referring to  FIG. 2 , one practical method for providing the friction means is a separate member affixed to the bottom surface  4  of a contact member  1  comprising a snap-in member  16  having means  17  for removably attaching the snap-in member  16  to the bottom surface  4  of the contact member  1 . This removable attachment feature may be readily provided by a post  18  affixed to each snap-in member  16  and which fits engagingly in a port  19  formed in the body of the contact member I, or by other like configuration. This embodiment offers several advantages in disposability and ease of manufacture, particularly where it is desirable to provide an adhesive or friction-providing member separately to the bottom surface  4  of the contact member  1 , and especially where the friction or adhesive member is formed of a different material than the body of the contact member  1 . The bottom surface  4  of the snap-in member  16  may have any of the configurations described previously (See  FIGS. 1B and 1D  through  1 G). 
   Given the delicacy of the epicardial cardiac tissue, and the desire to avoid the possibility for damaging the heart as it beats throughout the beating heart bypass procedure, and to avoid the possibility that the stabilizing means might slip, the contact members  1  of the invention may be provided with a friction-providing and/or cushioning material at the lower or bottom surface  4  of the contact member  1  to cushion the point where the contact member(s)  1  engage the beating heart. For example,  FIG. 3  shows an exemplary material  20  comprising a textured soft rubber or fluid-filled member affixed to the bottom or lower surface  4  of the contact members  1  to prevent damage to the heart tissue, and to minimize slippage. 
   As noted above, a fundamental element of the invention is the contact members which engage the surface of the beating heart, in some embodiments proximal to the site of the anastomosis, to directly apply the stabilizing force to the beating heart. The actual shape, size, configuration, and relative orientation of the contact members may vary without departing from the spirit of the invention. For example, referring to  FIGS. 4A and 4B , the contact members  1  that engage the surface of the beating heart may be provided by a solid structure  21 , preferably a dense metal, which provides an added weight to add to the stabilizing effect achieved by contacting the beating heart with the stabilizing means of the invention. This embodiment facilitates motion cancellation and stabilization of the beating heart by adding additional weight directly at the site where the contact member engages the beating heart, which in this embodiment is at the site of the anastomosis. As can be seen in  FIG. 4B  through line A-A of  FIG. 4A , in this embodiment two contact members  1   a ,  1   b  engage the beating heart at their lower or bottom surface  4 , have a greater thickness at their outer edges, and have an opening  22  positioned therebetween, and which traverses the entire space between the contact members  1   a ,  1   b  such that a vessel may be positioned therebetween. 
     FIG. 4C  shows an integrated apparatus which may advantageously apply the contact members  1  to the surface of the beating heart by the action of a balance provided by an adjustable weight  24  and counterweight  25  mounted on opposite ends of a shaft  26  mounted on a fulcrum  27  which is preferably affixed to a stable support such as the operating table or an access platform providing retraction during the surgery. By manipulating the adjustable weight  24 , varying degrees of stabilizing force may be applied to the beating heart via shaft means  3  and the contact members  1 . This embodiment provides a continuously variable quantity of stabilizing force directed downward by the positioning of the weights  24 ,  25  and the rotation of the shaft  26  about the point of the fulcrum  27 . Thus, in use, the surgeon may rest the contact members  1  on the surface of the beating heart with a minimal force applied, and by moving the adjustable weight  24  away from the fulcrum, cause additional force to be applied, via the shaft means  3 , and the contact members  1 , to the surface of the beating heart. 
   The positioning of the contact members  1  at the surface of the beating heart to provide the requisite degree of stabilization may be achieved by several techniques designed to apply a mechanical force to the contact members that rest in a conformingly fashion at the surface of the beating heart to substantially arrest the movement in an atraumatic manner. The device shown in  FIG. 5  has a pair of contact members  1   a ,  1   b  disposed in substantially parallel fashion as in the embodiments previously described. However, the device has an additional counter contact member  28  that also engages the surface of the beating heart, but does so at a point slightly removed from the point of engagement of the other contact members  1   a ,  1   b  which are preferably located at the site of the anastomosis. Additionally, the shaft means  3  may be attached to and be rotatable about a point  29  located between the contact members  1   a ,  1   b  and the counter contact member  28  and preferably at a point on the connecting shaft  2  that is slightly elevated. The shaft means  3  is preferably rotatable, for example by virtue of a ball joint  30 , about the point  29  of contact thereby permitting the contact members  1  to self-align and engagingly conform to the surface of the beating heart. Moreover, in this embodiment, when a stabilizing force is applied to the surface of the beating heart, the force directed down the length of the shaft means  3  is not centered over the site of the anastomosis. The counter contact member  28  may also be configured to occlude the target vessel  31 . As with the other embodiments disclosed herein, an embodiment of the type of  FIG. 5  may be selected by the surgeon depending on the particular clinical indication, the particular physiology of a given patient; and/or the surgical environment dictated by the access method used to gain access to the beating heart, for example, stemotomy, thoracotomy, or puncture incision. 
   Thus, different surgical methods of access, different target vessels, and the anatomical differences between individual patients, may dictate the use of alternate embodiments of the invention, typically at the discretion of the surgeon. For this reason, contact members which are continuously adjustable, may be particularly preferred for some clinical indications. For example,  FIGS. 6A and 6B  show an embodiment of the invention having a plurality of particles or beads  32  disposed within a substantially flexible tubular structure or structures  33 , and which may have a vacuum lumen (not shown) located therein, to provide a contact means  1  whose shape and position is adjustable. Preferably, the flexible tube structure  33  has a malleable member  34  such as a wire disposed along the length thereof to provide a structural memory function and additional tensile strength. In the embodiment of  FIG. 6A , the flexible tube  33  is a single unitary structure which can be bent, typically in a U-shape configuration, to engage the surface of the heart and may have a plurality of discs  35  disposed along the malleable member  34 . Also, as illustrated by  FIG. 6B , the stabilizing means may be provided by a plurality of contact members  1   a ,  1   b  as otherwise described herein. As with the single unitary structure of  FIG. 6A , the plurality of the flexible contact members  1   a ,  1   b  may be provided with a plurality of beads or particles  32  disposed therein and may additionally have the ability to be inflated selectively, or selectively deflated, to adjust or fix the position of the contact members  1 . When suction is applied via the suction lumen, the particles  32  are compressed by atmospheric pressure causing the tubular structure  33  to become rigid, thereby fixing the information of the contact members  1 . 
   As with the embodiments described above, adjustable placement of the contact members may be particularly useful in a minimally invasive procedure. Contact members that releasably contact or are releasably attached to a shaft may be deployed by separate insertion of the contact member, and a shaft or shafts which may be independently introduced, manipulated, and withdrawn to provide a stabilizing device held in place by pressure exerted on the shafts while the anastomosis procedure is performed at which time the contact members and shafts are removed in an atraumatic manner. Referring to  FIGS. 7A and 7B , a unitary contact  1  has a plurality of recessed ports  36  adapted to receive the distal end  37  of a shaft means  3 , wherein the distal end  37  is shaped to fit conformingly within the recessed port  36  and wherein the shaft means  3  may be removably attached to the contact member  1 . As seen in  FIG. 7B , this embodiment provides the advantage that the shaft means  3  may be introduced through a plurality of very small incisions such that several shaft means  3  may removably engage the contact member  1  at the several points about the periphery of the contact member  1  where the recessed ports  36  are formed in the contact member  1  and receive the distal end  37  of a plurality of shaft means  3 . 
     FIG. 7C  illustrates a separate removable shaft means  3   a  that may be utilized with any of the embodiments of the contact members  1  previously described. In  FIG. 7C , the separate shaft means  3   a  is separately introduced and has a pair of distal ends  37  that engage equivalently oriented and spaced ports  36  found in the contact member  1  to provide an additional positioning and stabilizing capability by manipulating the separate shaft means  3   a  when the distal ends  37  engage the ports  36 . 
     FIG. 7D  is a simplified use of separate shaft means  3   a  having an integral contact member  1  formed from the distal portion  38  of the separate shaft means  3   a . In this embodiment, the separate shaft means  3   a  are separately introduced into the surgical field through minimally invasive puncture incisions and are separately positioned to bring the distal portion  38  of each of the separate shaft means  3   a  to contact the surface of the heart. Referring to  FIG. 7E , the separate shafts  3   a  may be joined at the most distal tip by a discrete interconnecting member  39  having openings  40  configured to receive the most distal tip  37  of both of the separate shaft means  3   a.    
     FIG. 8  is an additional embodiment of the contact members  1  of the invention generally comprised of an annular structure  41  which is rotatable relative to the shaft means  3  which is attached at a point about the periphery of the contact member  1 . In this embodiment, a portion of the bottom surface  4  of the annular portion  41  contacts the beating heart at a site proximate to the target site for the anastomosis. The annular portion  41  of the contact member  1  may be provided with a lockable fixture  42  which engages the distal end of the shaft  43 , where the shaft means  3  contacts the annular structure  41 , to lock the shaft in place. Alternatively, the shaft means  3  may rotate freely about the periphery of the annular portion  41  of the contact member  1 . Preferably, a portion of the annular contact member  41  has a passage  44  formed through the bottom surface  4  of the annular contact member  41  where the target vessel  45  passes beneath the annular contact member  41 . Additionally, the annular contact member  41  may have substantially planar surfaces  46  which are generally co-planar with the bottom surface  4  of the annular contact member  41  and have a rectangular opening therein for access to the target vessel  45 . Planar surfaces  46  may assist in providing stabilization at the tissue proximate to the anastomosis, and which also assist in positioning the target vessel  45  relative to the annular contact member  41 . 
   The contact members of the invention may also be provided with other related apparatus or fixtures that are commonly used in traditional surgical procedures. Such structures or fixtures may be operably associated with the body of the shaft means  3 , the interconnecting shaft  2 , or the contact members  1 . 
   Referring to  FIGS. 9A through 9E , a suction (negative) pressure or a blower (positive) pressure is useful to maintain a clear and dry anastomosis site. The positive or negative pressure may be provided to the contact member by a plurality of ports  47  formed in the body of the contact member. Each port is in pneumatic communication with a lumen  48  that is in turn connected to a suction or positive pressure source. Thus, by exerting either a positive or negative pressure on lumen  48 , the suction or positive pressure is applied to the site of the anastomosis via ports  47 . In  FIG. 9A , the ports  47  are disposed in the top surface of the contact members  1  and have aligned openings in the direction of the anastomosis site. 
   As shown in  FIG. 9B , the plurality of ports  47  may be provided in a discrete lumen  48  which is affixed to, and runs longitudinally along, the length of the contact member  1 . In this configuration, the plurality of ports  47  are preferably disposed in a linear configuration along one surface of lumen  48  to provide negative suction pressure or a positive flow of pressure about the surface of the contact member  1 . 
   Referring to  FIG. 9C , as mentioned above, the plurality of ports  47  and the lumen  48  may be provided in a manifold-like fashion wherein the openings of the plurality of ports  47  are formed in the body of the contact member  1 , as is the lumen  48  which is in communication with each port  47 . As an alternate to the plurality of ports  47 , a single slot may be formed from the lumen  48 , such that the slot runs along the greater length of the contact member  1  as shown in  FIG. 9D . 
   Referring to  FIG. 9E , in a variation on the embodiment of  FIG. 9B , the lumen  48  may be provided as a malleable tube which is separable from the contact member  1  along at least a malleable portion  49  of said lumen  48 . In this configuration, by manipulating the malleable tube portion  49  of lumen  48 , port(s)  47  may be selectively positioned at any point proximate to the contact member  1 . 
   Referring to  FIG. 9F , a manifold similar to that shown in  FIG. 9C , may be provided within the body of the contact member  1  in a configuration wherein the ports  41  are more closely associated with the interconnecting shaft  2  or the shaft means  3 . As in the embodiment of  FIG. 9C , the ports  47  are in communication with a lumen  48  that runs the length of the shaft means  3  terminating in the plurality of ports  47 . As shown in  FIG. 9F , the plurality of ports  41  may apply the positive or negative pressure from the portion of the interconnecting shaft  2  that joins the individual contact members  1 . 
   Referring now to  FIG. 9G , as in  FIG. 9E , a lumen  48  having a malleable portion  49  may be provided for selective positioning of a positive or negative pressure which may be applied at any point proximate to the stabilizing means of the invention by manipulating the position of the malleable portion  49  of the lumen  48  to selectively position port  47 . 
   In a similar structural configuration to  FIGS. 9A through 9G ,  FIG. 9H  supplies an incandescent or fiber optic light source  48   a  proximate to the contact members  1  by placing the light source within the shaft means  3  to have an opening or lens to provide light at the site of the stabilization. 
   An additional conventional surgical apparatus which may be advantageously applied to the stabilizing means of the present invention is a selectively positionable surgical drape that assists in providing a dry and sterile field, and which assists the surgeon during the procedure by visually isolating the site of the anastomosis.  FIG. 10A  shows a retractable and extendable drape  50  surrounding shaft means  3 . In the retracted configuration  51 , shown in phantom in  FIG. 10A , the retractable drape is closely conformed to the shaft means  3  to be unobtrusive. The drape  50  may be affixed to the shaft means  3  by a washer element  52  that is directed downward to deploy the drape  50 . When the washer element  52  reaches the maximum downward position, the retractable drape  50  is doubled over to form a portion of a circular covering surrounding the surgical site and generally opposite the area where the contact members  1  abut the surface of the beating heart. An additional embodiment, shown in  FIG. 10B , has a surgical drape  50  affixed to the outer portion of each contact member  1   a ,  1   b . While this configuration is not retractable, surgical drapes  50  as shown in  FIG. 10B  may be provided with structural support members  53  that provide tensile strength and shape to the surgical drape  50  and which may provide supplemental stabilizing force by contacting the beating heart about the periphery of the contact members  1   a ,  1   b . An additional configuration for surgical drapes  50  affixed to contact members  1  is shown in  FIG. 10C  where a plurality of drape supports protrude radially from several points about the periphery of the contact members  1   a ,  1   b  and terminate in drape fastening means  54   a  at their most distal portion. A portion of the drape  50  is attached to each drape fastening means  54   a  to spread the drape over the surgical site and may provide coverage extending in all directions outward from the contact members  1 . 
   Referring to  FIG. 11 , a mechanical fixture to facilitate completing the anastomosis may be directly attached to the contact member  1 . A separate device to facilitate completing the anastomosis is generally comprised of a hinged or rotatable vessel support member  55  that permits selective positioning of the source vessel  59 , such as the distal end of an internal mammary artery or the distal end of a venous or arterial graft, proximate to the target vessel  56 . The vessel support member  55  is oriented on the contact member  1  such that the vessel source brought into direct alignment with an arteriotomy formed in the target vessel  56 , which is disposed between the contact members  1 . To facilitate the completion of the anastomosis, a vessel receiving member  57  is closely associated with the contact members  1  and generally surrounds the arteriotomy in the target vessel  56 . The vessel support member  55  has an anastomosis coupling fixture  58  that is attached to the distal end of the source vessel and is shaped to be brought into engagement with the vessel receiving member  57 . The anastomosis coupling fixture  58  is attached to the periphery of the IMA or graft such that when the vessel support member  55  is positioned proximate to the arteriotomy, the vessel receiving member  57  and the anastomosis coupling fixture  58  are brought into alignment such that a fluid communication between the source vessel  59  and the target vessel  56  is established upon completion of the anastomosis. Completion of the anastomosis is facilitated by an automatic suturing securing mechanism  60  or other like apparatus for tightening the sutures to join the two vessels. Preferably, the vessel receiving member  57  and the anastomosis coupling fixture  58  are operably associated with a plurality of sutures  61  which penetrate the periphery of the arteriotomy formed in target vessel  56  and connect the periphery of target vessel  56  to the periphery of the source vessel  59 . Thus, while simultaneously actuating the vessel support member  55 , the automatic suturing device  60  brings the vessels into close conformity and completes the anastomosis procedure to establish fluid communication between the source vessel  59  and the target vessel  56 . 
   Referring to  FIG. 12 , a separate member for conveniently holding the source vessel may be provided without a dedicated apparatus for completing the anastomosis. A malleable wire  62  is operably affixed to the shaft means  3  or to the contact member (not shown) and has a source vessel holder  63  such that the source vessel  64  may be prepared and conveniently held at a point away from the target vessel  56  until the surgeon is prepared to complete the anastomosis. Preferably, the source vessel holder means  63  is comprised of a clamp for gripping and maintaining the source vessel  64  in a preferred configuration prior to completing the anastomosis, such as by separating or spreading the tissue attached to the most distal portion of the source vessel  64  to maintain the integrity and patency of the distal end of the source vessel  64 . 
   As mentioned above, it is particularly preferred that the instruments of the invention be used in a minimally invasive bypass graft procedure wherein a minimal thoracotomy provides access to the beating heart. A minimal thoracotomy is a small surgical opening provided between the ribs and is formed, to the extent possible, proximate to the target artery of the beating heart where the anastomosis is to be formed. To provide access to the beating heart via the minimal thoracotomy, a cannula may be disposed between the ribs to provide access to the beating heart. Referring to  FIGS. 13A through 13E , alternate configurations for a cannula disposed between adjacent ribs are shown. The embodiment of  FIG. 13A  has a cannula support bracket  67  having a plurality of holes through which screws  66  may pass to provide means to attach the assembly to the chest such as by placing the screws in adjacent ribs  69   a ,  69   b . The cannula receiving assembly  67  may have one slot  65  formed therein such that one of the screws  66  may slide therein for spreading the adjacent ribs  69   a ,  69   b  apart. The cannula receiving assembly  67  provides an opening between adjacent rib&#39;s  69   a  and  69   b  such that the cannula  68  may be passed therethrough. Referring to  FIG. 13B , in an alternate embodiment, the cannula receiving assembly  67  is replaced by a cannula  68  surrounded by a large thread means  70 . The distal end  71  of the cannula  68  may be inserted between the ribs and rotated such that the thread means  70  cause cannula  68  to be advanced between the adjoining ribs  69   a ,  69   b , and by virtue of the expanding diameter of the thread means  70 , to spread adjoining ribs  69   a ,  69   b  apart while positioning the cannula  68  therebetween. In yet a further embodiment, in  FIG. 13C , a cannula assembly  75  is provided having a claw mechanism comprised of opposing blades  73  and interlocking member  72 . Adjacent ribs  69   a ,  69   b  are engaged by opposing blades  73 , and, by forcing the cannula  68  downward, the opposing blades  73  rotate outwards until a locking member  72  fixes the position of the opposing blades  73  in a locked and opposing relationship as shown in  FIG. 13D and 13E . Thus, by forcing cannula  68  downward, adjacent ribs  69   a  and  69   b  are spread apart by opposing blades  73  and the cannula assembly  75  is fixed in position by locking member  72  such that cannula  68  is positioned to provide access to the beating heart. 
   A modified large diameter cannula having an extended vertical height may perform several functions in a minimally invasive CABG procedure. For example, referring to  FIG. 14 , an enlarged cannula  74  may be provided in the shape of an inverted cone structure having an enlarged proximal opening  76  with an enlarged diameter, and a distal opening (not shown) in distal portion  75  having a reduced diameter and where said distal opening  75  abuts the surface of said beating heart. By exerting a downward force on the inverted, enlarged cannula  74 , the inverted conical shape of the cannula  74  forcibly spreads adjacent ribs  69   a ,  69   b , and provides a stabilizing force when the distal portion  75  contacts the surface of the beating heart. Surgical access to the stabilized heart is provided through enlarged proximal opening  76 . 
     FIGS. 15A and 15B  show an embodiment of the invention in use with a conventional cannula. In  FIG. 15A , a conventional cannula  77  is inserted through a puncture incision in chest wall  80 . The distal end of the stabilizing means  78  (similar to  FIGS. 31A and 31B  below), is introduced in a contracted configuration through the cannula  77  to bring the distal end thereof in contact with the surface of the beating heart  79 . Referring to  FIG. 15B , the stabilizing means of the invention are fully inserted through the cannula  77  and manipulated to bring the contact members  1  into contact with the surface of the beating heart  79 . By manipulating handles  81  of the stabilizing means, the contact members  1  are spread apart at the surface of the beating heart to provide the stabilizing function during the surgical procedure. 
   Where a minimally invasive procedure is employed, the means for stabilizing the beating heart of the invention are preferably provided in an embodiment where the contact members  1  that engage the surface of the beating heart are inserted and withdrawn from the surgical field in a position or a configuration having a reduced dimensional profile, i.e., a reduced effective diameter when inserted and removed from the thoracic cavity. For example, these embodiments are particularly useful when the surgery is performed through a plurality of puncture incisions. 
   In the embodiment of  FIGS. 16A through 16E , a pair of rectangular and substantially planar contact members  1   a ,  1   b  are disposed within a generally cylindrical main shaft  82 . In the retracted configuration shown in  FIG. 16A , each contact member  1   a ,  1   b  is rolled into a collapsed, annular configuration to reduce the effective diameter of the device by having the contact members  1   a ,  1   b  maintained within the shaft  82  when the device is inserted through an incision. In this configuration, each contact member  1   a ,  1   b  is attached to a central shaft  83  by a connecting shaft  2  which has a tensioning wire  84  or spring mounted to the connecting shaft  2  and the central shaft  83  to deploy each contact member  1   a ,  1   b  when the central shaft  83  is extended from the substantially cylindrical main shaft  82  in which the contact members  1   a ,  1   b  are originally retained. Thus, in use, the contact members  1   a ,  1   b  are maintained in the retracted annular configuration of  FIG. 16A  until deployed within the surgical field as shown in  FIGS. 16B through 16E  by extending the central shaft  83  downward causing the contact members  1   a ,  1   b  to be deployed below the main shaft  82 . The contact members  1   a ,  1   b  unfold from their annular configuration and deploy into their substantially planar shape as shown in  FIG. 16C . The contact members  1   a ,  1   b  rotate into position relative to the central shaft  83  by the tension in wire or spring  84  which is preferably disposed to act upon the connecting shaft  2  to cause contact members  1   a ,  1   b  to be fixed in a substantially parallel position to one another and substantially co-planar with the surface of the beating heart as shown in  FIGS. 16D and 16E . 
   Thus,  FIG. 16A  shows the contact members  1   a ,  1   b  in their collapsed or retracted position.  FIG. 16B  shows the contact members in the process of being deployed as the central shaft  83  is extended from the bottom of the main shaft  82 .  FIGS. 16D and 16E  show the tensioning wire  84  for repositioning the contact members  1   a ,  1   b  in the desired position for use in surgery.  FIG. 16C  shows the central shaft  83  fully extended from the bottom of the body of the main shaft  82  causing the deployment of the contact members  1   a ,  1   b  into the desired configuration for stabilizing the beating heart. 
   Preferably, the connecting shaft  2  joining the individual contact members  1   a ,  1   b  is hinged  85 , such that upon completion of the anastomosis, the contact members  1   a ,  1   b  may be withdrawn by pulling the central shaft  83  upward relative to the main shaft  82  and into the body of the device, thereby causing the contact members  1   a ,  1   b  to be removable in a low-profile configuration. 
   Referring to  FIGS. 17A through 17D , a similar strategy as is shown in  FIGS. 16A through 16E  is used whereby a pair of contact members  1   a ,  1   b  are deployed by a main shaft  86  within a hollow portion of the body  87  of the device. In the embodiment shown in  FIGS. 17A through 17D , a pair of non-flexible contact members  1   a ,  1   b  may be provided to stabilize the beating heart in a minimally invasive environment by containing the contact members  1   a ,  1   b  in a body or housing  87  which is inserted through the minimally invasive incision. In this embodiment, the contact members  1   a ,  1   b  are mounted to a central shaft  86  by virtue of a pin or hinge  88  which affixes the end of the contact members  1   a ,  1   b  to the central shaft  86  such that the contact members  1   a ,  1   b  may be deployed by rotating around the pin or hinge  88  when the shaft  86  is extended downward from the body  87  of the device. The opposite portion of the contact members  1   a ,  1   b  (most distal from the hinge) may fit within a guide fixture  89  concentrically associated with the central shaft  86  that retains the contact members  1   a ,  1   b  in the desired configuration prior to deployment. In use, the central shaft  86  telescopes from an opening in the distal end of the body or housing  87  of the device by a distance at least as great as the overall length of the contact members  1   a ,  1   b , at which point the contact members  1   a ,  1   b  may be deployed and locked into position, for example, in an orientation substantially perpendicular to the shaft as shown in  FIGS. 17A and 17C . Once fixed in position by locking mechanism  90  as shown in  FIG. 17C , the central shaft  86  may be rotated using the guide fixture  89  which is positioned downward to engage the contact members  1   a ,  1   b . Thus, the guide fixture  89  engages the contact members  1   a ,  1   b , the pin  88 , or the locking mechanism  90 , and by applying mechanical force, the position of the contact members  1   a ,  1   b  may be adjusted. Upon removal, the central shaft  86  is withdrawn into the body  87  of the device. Alternatively, the housing  87  may disengage the locking mechanism  90  from the guide fixture  89  releasing the position of the contact members  1   a ,  1   b  thereby allowing the contact members  1   a ,  1   b  to be returned to their original or other configuration that allows the contact members  1   a ,  1   b  to be drawn into the body of the device  87  to facilitate minimally invasive removal thereof. 
     FIGS. 18A through 18D  show an analogous embodiment having contact members  1   a ,  1   b  retained in the undeployed configuration suitable for insertion through a minimally invasive incision. As shown in  FIGS. 18A and 18B , the contact members  1   a ,  1   b  may be maintained in a retracted position such that the length of the contact members  1   a ,  1   b  is substantially parallel to the central shaft  92 . The proximal end of each contact member  1   a ,  1   b  is affixed to the guide fixture  93  while the distal end (below the hinge at central portion  91 ) has the bottom surface  4  formed therein and is affixed to the distal end of the central shaft  92 . Referring to  FIG. 18C , the contact members  1   a ,  1   b  are deployed by the downward motion of the guide fixture  93 , such that the contact members  1   a , 1   b  fold about the central portion. When the guide fixture  93  is fully extended downward, the contact members  1   a ,  1   b  are formed of a pair of two-part structures wherein the lower structure contains the bottom surface  4 . 
     FIGS. 19A and 19B  show an additional embodiment having foldable contact members  1   a ,  1   b  wherein a central shaft  94  is affixed to a plurality of hinged struts  95  that are connected to opposite ends of contact members  1   a ,  1   b  about a hinged central portion  96 . When the central shaft  94  is extended downward, the hinged struts  95  deploy outward. As shown in  FIG. 19A , the individual contact members  1   a ,  1   b  fold at the central hinged portion  96  to reduce the overall dimensional profile of the device for minimally invasive insertion or removal. When fully deployed ( FIG. 19B ), the contact members  1   a ,  1   b  are extendable to a substantially planar configuration as with other embodiments disclosed herein. 
     FIGS. 20A through 20E  show the central shaft  97  and contact members  1   a ,  1   b  with alternate configurations for positioning the contact members for minimally invasive insertion and removal. Referring to  FIG. 20A , first hinges  98  are provided in the connecting shaft  2  such that the contact members  1   a ,  1   b  can be rotated approximately 90° out of their co-planar configuration. A second hinge  99  is provided between the shaft means  3  and the connecting shaft  2  to tilt the distal end of the contact members  1   a ,  1   b  downwards as shown in  FIG. 20C . The embodiments of  FIGS. 20D and 20E  show modified such that two interconnecting shafts  2   a ,  2   b  maintain the contact members  1   a ,  1   b  in slightly separate, yet parallel, vertical positions. A single hinge  100  with a vertical axis of rotation allows the contact members to be brought into close conformity before being tilted downward. 
     FIGS. 21A through 21C  show a deployable stabilizer of the invention having contact members comprised of a single continuous wire  101  that is deployable from within a housing or body  102  which is ideally inserted through a minimally invasive incision. As shown in  FIG. 21A , the single continuous wire  101  may be coiled and contained within the housing  102  such that the dimensional profile of the stabilizer is minimized for insertion. The wire  101  which forms the contact member(s) of this embodiment is preferably round and smooth, and may be formed of a material such as Nitinol that is collapsible, and deployable into a pre-determined shape. As can be seen in  FIG. 21B , following insertion, the wire  101  is extended from the body  102  of the device to form at least one loop  103  wherein at least one side  104  of the loop  103  contacts the surface of the heart. Preferably, at least two loops  103  extend from the body 
     102  of the device and are formed from a single wire  101 . In this configuration, maximum stabilization is achieved if substantial portions of the sides  104  of both loops  103  contact the beating heart proximate to the target vessel. As in the previous embodiments, the insertion and removal of the stabilizing device through a very small incision is least traumatic when the dimensional profile, or effective diameter, of the contact members in a retracted configuration is not substantially greater than the dimensional profile or diameter of the body  102  of the device. Thus, as can be seen in  FIG. 21C , the contact members of the embodiment of  FIGS. 21A through 21C  are drawn upward by exerting force on the wire  101 , and the contact members comprised of loops  103  are drawn into a configuration which is in alignment with the body  102  of the device such that their removal may be achieved through a puncture incision with minimal additional trauma to the patient. 
   In addition to a single continuous wire  101 , the contact members may be formed of a helical wire coil  105  as shown in  FIGS. 22A through 22C . As in the embodiments described previously, the contact members  1   a ,  1   b  are deployed by extending a tubular central shaft  106  through a body or housing  107  of the device to deploy the contact members  1   a ,  1   b . The downward motion of the central shaft  106  is terminated by the contact between a stop  109  and the distal end of the body  107 . The contact members  1   a ,  1   b  are withdrawn into the body  107  of the device upon completion of the surgical procedure by pulling the central shaft  106  vertically through the body  107  of the device. A predetermined curve in the helical coil  105  may be provided by spacing members  108  placed between adjacent individual loops  105   a  and  105   b  of the helical coil  105 . The central locking wires or cables may be tensioned upon deployment to increase the rigidity of the structure. 
   An additional configuration for minimally invasive insertion and removal is shown in  FIGS. 23A and 23B  wherein the contact members  1   a ,  1   b  are formed of an inflatable balloon  110  that is pre-shaped to provide any desired configuration of the contact members  1   a ,  1   b .  FIG. 23A  shows a pre-formed inflatable balloon  110  in an inflated state and extended from the housing  111 . Inflation is achieved by a central shaft  112  disposed within the central lumen  111 .  FIG. 23B  shows the inflatable balloon  111  in an un-inflated state for insertion or for removal. 
   Referring to  FIGS. 24A and 24B , an inflatable contact member may also be provided by a cuff  113  which is positioned such that the circumference of the cuff  113  contacts the beating heart and the ribs about its periphery. Preferably, the target vessel  114  is positioned to bisect an annular cuff  113  to provide maximum stabilization. Additionally, referring to  FIG. 24B , separate contact members  1   a ,  1   b  as previously described herein, may be integrally formed with the cuff  113  by mounting the contact members  1   a ,  1   b  in the wall of the cuff  113  to extend into the interior thereof. 
     FIGS. 25A and 25B  illustrate an embodiment of the invention which provides minimal trauma to the patient during insertion and removal of the stabilizing means by containing a simple stabilizer in an instrument having a housing  115  with an extremely limited cross-section such that the instrument can be inserted through an extremely small incision. In this embodiment, the entire stabilizing means is contained within the hollow housing  115  and is comprised of a pair of contact members  1   a ,  1   b  which are joined at the most distal end thereof. As can be seen in  FIG. 25B , the contact members  1   a ,  1   b  are formed from a unitary shaft  116  having a divided portion  117  at the distal end such that upon deployment from the housing  115  of the device, the divided portion  117  splits into two contact members  1   a ,  1   b  joined at their most distal tip  118  and which may be brought into contact with the beating heart along the divided portion  117  of the unitary shaft  116 . 
   In addition “to the friction means or cushioning members described above in  FIGS. 1B through 1G  and  FIG. 3 , sutures may be used to attach or position epicardial tissue relative to a contact member  1  to enhance the stabilization function of the invention and to position epicardial tissue or the target vessel of the anastomosis.  FIGS. 26A ,  26 B, and  26 C show embodiments where means for fixing the position of epicardial tissue is comprised of sutures  119  used in combination with the contact members  1   a ,  1   b  to stabilize and position tissue surrounding the site of an anastomosis and the target cardiac artery. In  FIG. 26A , a series of sutures  119  is placed through the epicardial tissue (not shown) and looped around the contact members  1   a ,  1   b  to effectively position several points on the surface of the beating heart in fixed relationship to the contact members  1   a ,  1   b . In  FIG. 26B , the contact members  1   a ,  1   b  and optionally the shaft means  3  associated therewith have passages  120  formed therein through which a suture line  119  may be passed. In the particular example of  FIG. 26B , a single suture  119  is passed through the body of the shaft  3 , exits from within the first contact member  1   a  through a passage  120  formed therein, passes underneath the target vessel  121 , emerges from an opposite side of the target vessel  121 , and enters a passage  120  in the opposite contact member  1   b  joined to the first contact member  1   a  by the connecting shaft  2 . The suture  119  exits the opposite contact member  1   b  again passes beneath the target vessel  121 , reenters the first contact member  1   a  at a separate passage  120 , and passes through the body of the first contact member  1   a  and into the shaft means  3 . In this configuration, the suture lines may be manipulated by the surgeon from a remote location, such as external to the incision in the chest, to remotely position the vessel by drawing tension on the suture line  119 .  FIG. 26C  shows a similar arrangement for the suture line  119  as in  FIG. 26B , however in  FIG. 26C , apertures  122  in the body of the contact member  1  are used to select the direction of the suture  119  rather than having passages  120  which traverse the body of the contact member  1 . Also in this or the other embodiments, a separate sliding shaft  123  may be provided that gathers and is traversed by the sutures  119 . The step of drawing tension on the suture line  119  is facilitated by advancing the sliding shaft  123  to abut the contact member  1  and exerting a small downward force on the sliding shaft  123  while exerting an upward force to draw tension on the suture line(s)  119 . By maintaining downward force on the sliding shaft  123 , the target vessel  121  is raised while the potential for displacing the contact member  1  is minimized because the upward force exerted on the suture lines  119  is countered by the downward force exerted on the sliding shaft  123 . 
   Referring to  FIGS. 27A and 27B , a modification of the contact member  1  of the invention may be provided by a structure formed at the distal end of the shaft means  3  and which is inserted directly into the arteriotomy  124  formed in the target vessel  125 . This intravessel stabilizer  126  has a body designed to fit conformingly about the interior of the target vessel  125 , and may be in communication (including fluid communication) with a hollow portion of the shaft means  3 . The body  126  of the intravessel stabilizing means may be a substantially cylindrical lumen as shown in  FIG. 27B  and should have an overall length which is greater than the length of the incision creating the arteriotomy  124 . Additionally, in the embodiment of  FIG. 27B , the intravessel stabilizer  126  may be perpendicular to the shaft means  3  and have cuffs  127  at the distal end of the body  126  to provide conforming engagement with the interior of the target vessel. As shown in both  FIGS. 27A and 27B , this embodiment of the stabilizing means of the invention is preferably used in connection with a plurality of sutures  128  that penetrate the edges of the target vessel about the circumference of the arteriotomy  124 . By exerting pressure on the shaft means  3  and the plurality of sutures  128 , the target vessel is stabilized, and its position may be manipulated, to facilitate completion of the anastomosis. 
   In addition to stabilization of the beating heart proximate to the target vessel of the anastomosis, additional fixtures, structures or elements associated with the contact members  1  can be used to retract or fix epicardial tissue proximate to the target vessel and the site of the anastomosis by using a means for gripping epicardial tissue at the surface of the exterior of the heart. The means for gripping may be provided by several different embodiments. For example,  FIG. 28A  shows a functional clamp  128  formed by a crimping contact member  1  that has a fold  129  disposed longitudinally at the center of the length of the contact member  1 . When force is applied to the sides of the contact member  1  opposite the fold  129 , the crimping action of the contact member  1  grasps the epicardial tissue  130  at the heart surface  131  and contains it within the folded contact member  132 . In another embodiment, as shown in  FIG. 28B , a plurality of open passages  133  are provided in a contact member  1  that has a slidable member  134  disposed within a slot  135  formed within the contact member  1 . When sufficient force is exerted in a downward direction on shaft  3  to force epicardial tissue  130  through the open passages  133 , the slidable member  134  then may be actuated to grip the tissue  130  contained within the open passages  133 . By gripping a portion of epicardial tissue  130 , the tissue may be spread to more readily expose the target vessel  136  of the anastomosis. 
   A similar function is provided by a pair of contact members  1 , that are formed of circular rollers  137  that lie longitudinally parallel to the direction of the target vessel  136  as shown in  FIGS. 29A and 29B . The contact members  1  may be comprised of movable rollers  137 , belts, or pivoting surfaces that may be rotated independently about an axis  138  dedicated to each contact member  1  such that the epicardial tissue  130  is gathered or spread, depending on the respective directions of rotation of the rollers  137 , as desired at the surface of the heart to expose the target vessel  136 . As will be apparent to those skilled in the art, each of these embodiments may be provided with contact members  1  that are independently movable in a parallel, V-shaped, or other adjustable configuration as described and illustrated herein. 
   Referring to  FIG. 30 , the contact members  1  may be further comprised of a spring-tensioned frame  139  having a movable frame extension  140  which may have pins or an associated friction means at the bottom surface  4  of the contact members  1   a ,  1   b  to engage the tissue proximate to the target artery. The movement of the frame extension  140  is tensioned by a spring means  141  which draws the frame extension  140  toward the contact member  1  after the frame extension  140  has been manually positioned to engage the tissue. The use of this embodiment of the invention is the same as is described for the other embodiments herein, with the frame extension  140  providing the improved exposure of the target artery by retraction of the epicardial tissue. As with the other embodiments, the contact members  1  may be attached at one end by a connecting shaft  2  which is attached to a shaft means  3  as described above. The connecting shafts  2  may also be positioned relative to one another by a conventional threaded post  142  with a positioning thumbscrew  143 . 
   Referring to  FIGS. 31A and 31B , the stabilizer means may also be comprised of a single shaft means  3  connected to each contact member  1 . In a preferred embodiment the shaft means  3  are interconnected at an intermediate pivot point  144  which permits the contact members  1  to be continuously positioned in parallel fashion relative to one another. The proximal (upper) portion at the individual shaft means  3  may have grips adapted to be grasped by the hand or may have an anchor portion  145  for attachment to a retractor or other fixed support. As with the other embodiments described herein, the length of the shaft means  3  may be adjustable by a conventional telescope configuration. In such a configuration, a first shaft  148  has a partially hollow segment  147  adapted to receive the complimentary portion of the second shaft  148 . Either first  146  or second  148  shafts may be connected to the contact members  1  and may each have a conventional interlocking mechanism  151  to fix the relative positions of the shafts. The shaft means  3  may also have a tensioning spring mechanism  150  having an axis  149  which is displaced between a portion of the shaft means  3  affixed to the contact members  1  and the remainder of the shaft means  3 . In this configuration, the contact members  1  remain tensioned against the heart proximate to the anastomosis site when the proximal end of the shaft means  3  is affixed to a stable support. This embodiment also preferably has a friction means as described above affixed to the bottom surface  4  of each contact member  1 . An additional advantage of this embodiment is derived from the capability to move the contact members  1  apart from one another in a parallel configuration. Thus, the contact members  1  can first be positioned to engage the surface of the heart tissue followed by the application of a stabilizing force in combination with spreading or joining of the proximal (upper) end of the shaft means  3 . Application of a stabilizing force causes the tissue on either side of the target artery to be spread or compressed while the heart is stabilized. Thus, by coincidentally spreading or joining the proximal portion of the shaft means  3 , the epicardial tissue engaged by the contact members  1  is stretched or compressed to provide stabilization and improved exposure and positioning of the target coronary artery. 
   Referring to  FIGS. 32A through 32C , the contact members  1  may have associated therewith additional structures which serve to position or retract epicardial tissue, at or around the surface of the heart, particularly tissue in the vicinity of the site of the anastomosis. Often, the surgeon wishes to retract the epicardial tissue near the target vessel to increase exposure of the vessel where the anastomosis is to be performed. Additionally, these associated structures provide an additional amount of stabilization by actually penetrating the tissue at the outer layer of the heart and holding the tissue in close conformity to the contact member. 
   Referring to  FIG. 32A , epicardial tissue retractors are provided by a series of curved pins  152  which generally extend from one contact member  1   a  to the other  1   b  by virtue of a guide  153  attached to the bottom of each contact member  1 , each of which is dedicated to a single pin  152 . In this embodiment, a plurality of pins  152  are substantially parallel to one another and may be inserted and positioned to pass beneath the vessel where the anastomosis is to be performed. In this fashion, the surgeon can position the vessel, by virtue of the tissue engaged by the pins  152  and the contact members.  1   a ,  1   b  in any direction. This embodiment is particularly useful to vertically displace the tissue, i.e., in a direction perpendicular to the shaft means  3 . 
   An additional embodiment is shown in  FIG. 32B , whereby a plurality of short pins  154  extend down from the bottom surface  4  of the contact member  1  to enter the epicardial tissue. The short pins  154  may extend in a direction substantially perpendicular to the surface of the issue and the bottom surface  4  of the contact member  1 , or may be angled outward to engage the tissue. The advantages of this embodiment are best utilized with a stabilizing means wherein the individual contact members  1   a ,  1   b  may be selectively positioned such that the distance between the individual contact members is varied. Thus, the contact members  1   a ,  1   b  can be brought into contact with the surface of the beating heart followed by spreading the contact members  1   a ,  1   b  apart from one another to provide retraction and spreading of the epicardial tissue. This is readily achieved in the embodiment of  FIG. 32B , wherein a single shaft means is dedicated to each contact member  1   a ,  1   b , respectively and the individual shafts are joined by an intermediate pivot point  155 . 
   A similar embodiment is shown in  FIG. 32C , however, in this embodiment, while each contact member  1   a ,  1   b  has a dedicated shaft, the shaft  156  dedicated to the first contact member la is disposed within a hollow shaft  157  dedicated to the second contact member  1   b . In this configuration, each shaft  156 ,  157  may be individually rotated about the other to provide a V-shaped retraction of the epicardial tissue. In this embodiment, the epicardial retractor pins  154  are preferably similar in structure and orientation to the embodiment of  FIG. 32B . The pins in both designs could alternatively be curved or angled inward, and the contrast members  1  moved toward each other, providing a compression of the epicardium to stabilize the tissue and present the anastomosis site to best advantage. This action may also serve to occlude the blood flow in the coronary artery minimizing blood loss and obstructions of the visual field. 
   Referring to  FIGS. 33A and 33B , the stabilizer means may comprise at least one stabilizer plate which is attached to a stable support by the shaft means  3  and which may be used with a lever member  158  for improving exposure at the target artery while the anastomosis is completed. In this embodiment the means for stabilizing the beating heart comprises a left and right stabilizing plate  159 ,  160  which are oriented to exert a downward force on the epicardial tissue at either side of the target artery at the anastomosis site and which may be substantially planar or may be curved to conform to the surface of the heart. One or both of the stabilizing plates  159 ,  160  my have an edge  161  deflected downward along its length so that the edge  161  depresses the tissue proximate to the artery to increase the exposure of the artery during the completion of the anastomosis. Preferably, the edge  161  of the stabilizing plates  159 ,  160  has a separate lever member  158  running substantially parallel to the artery and on both sides thereof. The top portion of each lever member  158  contacts the underside of the stabilizing plates  159 ,  160 . In this embodiment, the lever member  158  is substantially cylindrical, traverses the stabilizing plate along its length, and is, oriented to be parallel to the edge  161  of the stabilizing plate  159 ,  160 . The lever member  158  is fixed in place, and may be affixed to the heart by a suture. In such a configuration, each of the stabilizing plates  159 ,  160 , which is in contact with the lever member  158  along its length contacts the heart such that the edge  161  depresses the tissue on both sides of the target coronary to restrict the movement of the beating heart. The stabilizing plates  159 ,  160  can be attached to one another or can move independently as desired. 
   Opposite the edge  161 , at a point separate from the lever member  158 , the stabilizing plates  159 ,  160  are connected to a shaft means  3  which holds the stabilizing plates  159 ,  160  in position and which may be manipulated relative to the lever member  158  to cause the edge  161  to engage the heart. The shaft means  3  is preferably affixed to each stabilizing plate  159 ,  160  at a point opposite the edge  161  and removed from the point where the lever member  158  contacts the stabilizer plates  159 ,  160  at a location to maximize leverage when the stabilizer plates  159 ,  160  are drawn upwards at the point of attachment of the shaft means  3 . The shaft means  3  may be constructed as described elsewhere herein and should be of sufficient length to facilitate manipulation of the shaft means  3  by the surgeon. As noted, the shaft means may also be attached to the retractor to fix movement of the stabilizing plates  159 ,  160  during the procedure. 
   In a preferred embodiment, the length of the shaft means  3  is adjustable relative to the retractor or other stable support. For example, the shaft means  3  may be telescopic as described above or may be comprised of a hollow post  163  which receives a rigid shaft  164  which is in turn fixed to the retractor. The rigid shaft  164  may also be substantially hollow and may have a suture or other line  165  passed therethrough and which also passes through the length of, the hollow post  163 . In this configuration, one end of the suture or line  165  is attached to the stabilizing plates  159 ,  160  and the other end extends through the hollow post  163  or the rigid shaft  164  to a position where it may be manipulated by the surgeon. The position of the stabilizing plate  159 ,  160  may thereby be remotely actuated. By drawing tension on the suture or line  165 , the stabilizing plate  159 ,  160  pivots about the lever member  158  and the edges  161  of the stabilizer plates  159 ,  160  depress the tissue on either side of the target artery. 
   Referring to  FIGS. 34A through 34E , a lockable mechanism may be provided to depress tissue on either side of a target vessel by a movable edge  176  formed along the edge of a block  177  which rotates about a support member  178  by means of a binge pin  179 . The support member  178  may be affixed to the upper surface of a contact member as described herein or may itself comprise the contact member. In use, as shown in  FIG. 34B , the block  177  is rotated about the support member  178  using hinge pin  179  until the movable edge  176  contacts the surface of the heart parallel to the target vessel  180  ( FIG. 34C ). The moveable edge  176  and block  177  are fixed in place by depressing locking member  181  to force the block  177  to rotate until an interconnecting member  182  extends the block  177  and edge  176  to fully depress the tissue proximate to the target vessel  180 . At this point, as shown in  FIG. 34D , the locking member  181  fixes the interconnecting member  182  in an extended position and is locked in place ( FIG. 34E ). The position of the block  177  may be released by actuating the locking member  181  to release the interconnecting member  182 . 
   Due to the fact that the heart continues to beat during the CABG procedures described herein, features of the invention which provide the capability to manipulate the target vessel, and to control the flow of blood therein, may greatly facilitate an efficient completion of the anastomosis. For example, additional components associated with the contact members  1  may be used to occlude the target vessel during the anastomosis procedure. Any of a variety of fixtures may be provided to operate in association with the contact members of the invention in order to occlude the vessel that is the target of the anastomosis. 
   Referring to  FIG. 35 , a stabilizing means  166  is comprised of a contact member which is substantially planar am has a substantially rigid surface  167  having a centrally disposed opening  168  in which the target artery of the anastomosis is positioned longitudinally through the opening. At either or both ends of the centrally disposed opening  168 , an occluder  169  extends below the surface  167  and engages the target artery to substantially reduce or eliminate the flow of blood through the artery. The occluder  169  is a deformable member having a smooth outer surface for adjustably contacting and depressing the target artery without damaging the tissue. The planar surface  167  of the stabilizing means also has an aperture  170  comprising an opening which traverses the entire planar surface  167  so that the graft can be passed through the aperture  170  when the anastomosis is completed. The planar surface  167  may also provide a mounting surface for springed tissue retractors  171  comprising a coiled spring  172  attached to the planar surface at one end and having a hook or pin  173  at the opposite end to engage and spread the tissue proximate to the anastomosis site to improve the exposure of the target artery. The planar surface  167  is attached to a post  174  which may be attached to a stable support such as a rib retractor. The planar surface  167  may also have at least one port  175  for receiving a suture line. 
   Referring to  FIG. 36 , the stabilizing means may have operably associated therewith an artery occluder  183 , which is preferably attached to the contact members  1  or to the connecting shaft  2 . The artery occluder  183  may comprise a semi-rigid member which has a blunt portion  184 , which may be positioned such that the blunt portion  184  engages the target artery  185  and compresses the target artery  185  to a point causing occlusion of the target artery  185  passing between the contact members  1  such that the blood flow through the artery is substantially reduced or eliminated. Preferably, the occluder  183  bas a shaft portion  186  which traverses the connecting shaft  2  such that the blunt portion  184  of the occluder may move from above the level of the target artery  185  to a point below the level of the original vessel sufficient to occlude the blood flow through the vessel. 
   Referring to  FIG. 37A , a concentrically movable shaft  187  is disposed within the shaft means  3  to which the contact members  1  are connected. In this embodiment, the target vessel  188  is positioned directly between and parallel to the longitudinal or greater length of the contact members  1 . When so positioned the concentric shaft  187  within the main shaft means  3  may be pressed downward such that the distal end  189  of the concentric shaft  187  encounters the vessel  188  and compresses the vessel, thereby occluding the vessel  188  to substantially prevent the flow of blood therethrough. This embodiment has the advantage that the amount of occlusion is continuously variable by varying the force applied and the distance by which the concentric shaft  187  is depressed relative to the shaft means  3 .  FIG. 37B  is a similar embodiment of the invention whereby a means for occluding the vessel is affixed directly proximate to the contact members  1 . In the example of  FIG. 37B , a pushbolt  190  is disposed on the connecting shaft  2  that joins opposing contact members  1  and is generally positioned in a raised portion thereof such that when the pushbolt  190  is not deployed downward, the vessel remains in its native position when oriented between the contact members  1 . Occlusion of the vessel  188  is achieved by pressing the pushbolt  190  down until the lower portion  191  engages the vessel  188  when the vessel  188  is disposed between the contact members  1 . This embodiment provides the ability to occlude the vessel  188  both proximal and distal to an arteriotomy  191  in the target vessel  188  at the site of the anastomosis. Referring to  FIG. 37C , a similar embodiment is provided by a roller  192  or clip mechanism  193  which is affixed to one or both contact members  1 , for example by a hinge  194 , which is selectively movable, to contact the target vessel  188  at a point either proximal or distal or both to the arteriotomy. In addition to positioning the target vessel for performing the anastomosis as shown in  FIGS. 26A through 26C  above, sutures associated with the stabilizer may be used to occlude the vessel to permit the anastomosis to be performed in a bloodless field. Referring to  FIGS. 38A and 38B , an embodiment of the invention may have a flange  195  protruding from the contact member  1  to permit silastic vessel loops or sutures  196  to be drawn about the target vessel  197  and the flange  195 . To occlude the vessel  197  the suture  196  is passed around the vessel  197  and drawn tight around the flange  195 . To facilitate occluding the vessel, a sliding shaft  198  may be used to surround the sutures  197  such that the suture lines  196  traverse the length of the sliding shaft  198  and extend out the bottom to surround the vessel  197 . In one embodiment, as shown in  FIG. 38B , the shaft  3  of the stabilizing means has a movable rod  198   a  having suture guides  199  disposed therein or operably associated therewith for adjusting tension on the suture lines. The movable rod  198   a  may be concentrically disposed within the shaft means  3  such that downward pressure on the shaft means  3  and upward pressure on the sliding shaft  196  draws tension on the sutures  196  to occlude the vessel  197 . 
     FIG. 39  shows modifications to the upper surface of contact members  1   a ,  1   b  of the invention wherein fixtures  201  are adapted to provide a resting place or attachment point for other surgical instruments such as scissors  202 , forceps  203 , or sutures and suture needles  204 . Preferably, the fixtures  201  are magnetic to facilitate retaining metallic surgical instruments in conforming contact with the upper surface of the contact member  1 . 
   Referring to  FIG. 40 , the contact members  1  of the invention and/or the shaft means  3  to which the contact members  1  are attached may be provided with one or more flexible joints  205  that permit positioning of either the contact members  1  or the shaft means  3  about an axis. Preferably, the flex joint  205  may be provided at the point where the shaft  3  engages the contact member  1  (not shown), at the point where the connecting shaft  2  engages the shaft means  3 , or at the point where the connecting shaft  2  is attached to the contact members  1 . 
   Thus, in the embodiment of  FIG. 40 , the flexible joint  205  provided at the point where the connecting shaft  2  is attached to each contact member  1  allows the connecting shaft  2  and the shaft means  3  to be tilted about an axis which is perpendicular to the target vessel. The flexible joint  205  provided at the point where the shaft means  3  is attached to the connecting shaft permits the shaft  3  to be tilted from side-to-side relative to the connecting shaft  2 . In the embodiment of  FIG. 40 , or in the embodiments described herein having hinges or flexible joints, the hinges or flex joints may be replaced by conventional lockable joints  206 , as shown in  FIG. 41 , that are selectively locked and unlocked mechanically as with forceps  207 . 
   As can be seen, such occluders are similar to the stabilizing contact members  1  described in several other embodiments herein, and can be expected to provide significant stabilization of the beating heart. These occluders can be used in conjunction with other stabilizing means or independently. They may be placed beside, rather than upon, the coronary artery to provide stabilization without occlusion, if desired. In like fashion, most of the contact members  1  of other embodiments will provide some occlusion of blood flow if placed upon, rather than beside, the target vessel. 
   As will be described in individual embodiments below, the shaft means  3  may be attached to or comprised of, a conformable arm which is used to position the contact members against the heart, and then to lock the stabilizing means in place once a stabilizing force has been exerted. The conformable arm is flexible and lockable and may have several configurations including a plurality of links, segments, or universal joints in serial configuration and having a cable fixture passed through the interior of the links which causes the entire conformable arm to become rigid by tightening the cable fixture. Also, the conformable arm may be comprised of a synthetic gel or polymer contained within a conformable cylindrical housing and which becomes rigid upon exposure to light or heat, such as the commercially available Dymax 183-M. Where the shaft means  3  is further comprised of the conformable arm, the conformable arm may be attached directly to the connecting shaft  2  or the contact members  1 . 
   Referring to  FIG. 42 , this embodiment of the invention is a means for stabilizing the beating heart wherein the shaft means is comprised of a flexible, lockable arm  208  having a plurality of interconnecting links  209  which allow positioning of the flexible arm  208  in every direction until the desired configuration is achieved at which point the flexible arm  208  may be locked into fixed configuration by tightening a cable fixture (not shown) attached to a cable  210  running axially through the interconnecting links  209 . Each interconnecting link is comprised of a ball portion  211  and a receiving portion  212  such that the ball portion  211  fits conformingly within the receiving portion  212 . The proximate (uppermost) end of the flexible, lockable arm  208  can be attached to a stable support, or to the retractor. In a preferred embodiment, the flexible, lockable arm  208  is a series of interconnecting links  209  having a cable  210  running through the center of each interconnecting link  209  such that when tension is exerted on the cable  210  the flexible, lockable arm  208  is fixed in a rigid position.  FIG. 42  also shows an embodiment of the invention wherein the contact members  1  are comprised of a pair of substantially parallel elements  1   a ,  1   b  which are positioned to receive a simple snap fixture  213  which is affixed to the surface of the heart. In this embodiment, the snap fixture  213  is positioned between the two parallel elements  1   a ,  1   b  of the contact member  1 , in order to fix the position of the heart tissue relative to the contact members  1 . As in the above embodiment, the contact members  1  are preferably oriented in a substantially parallel fashion with the target artery of the anastomosis passing therebetween. The snap fixtures  213  are affixed to the heart by a suture, wherein the suture line  214  may then also be attached to the contact member  1  via a notch, which may form a one-way locking mechanism to secure the suture line  214 , or may be attached to a circular post disposed in the body of the contact member  1  (not shown). The suture line  214  then may be tied through the notch or to the post in the contact member  1 , to the contact member  1   a ,  1   b  itself, or to the connecting shaft  2  to more tightly secure the heart to the contact member  1 . An additional advantage of this embodiment is that the stabilizing means is actually affixed to the cardiac tissue via the suture line  214 , such that when the heart is moving laterally or downward the artery being stabilized remains immobile and the surface of the heart may be lifted using the shaft means  3 . 
     FIG. 43  shows an alternate embodiment of the flexible lockable arm  208  attached to a retractor blade  279  and having a series of interconnecting links comprised of sphere joints  215  and cylindrical tubes  216  and which may have a tensioning cable traversing the length of the flexible, lockable arm as in the design of  FIG. 42 . Additionally, these embodiments may have other tensioning means such as an inflatable internal balloon  217  that expands against the interior of the links rendering the individual links immobile, and thereby locking the entire arm  208  into a fixed position. 
   Additionally the flexible, lockable arm  208  may be provided by a plurality of curved or bent tubular segments  218  as shown in  FIG. 44A  that are interconnected by an internal tensioning cable  210  or other tightening means. In the embodiment of  FIG. 44A , the curved or bent tubular segments  218  have interfacing surfaces  219  with teeth  220  such that when brought into conforming relationship, the curved tubular segments  218  do not rotate relative to one another due to the interlocking relationship of the teeth  220 . See  FIG. 44B . As above, the flexible lockable arm  208  is fixed in position by applying tension via a centrally disposed tensioning cable  210  or other tensioning means such as a spring-loaded rod, bolt, or wire. The interconnection between adjoining segments  218  may also be facilitated by bushings  221  that are disposed around the wire  210  and are shaped to fit within a recessed portion  222  of interfacing surface  219 . 
   Referring to  FIG. 45A , a continuously flexible, lockable arm  208  is provided by a hollow flexible shaft  223  having a material  224  disposed within which may become semi-rigid or stiff by a variety of methods. In use, the contact members  1  are positioned at the desired orientation relative to the beating heart, and the material  224  inside the flexible shaft  223  is caused to be rendered stiff or semi-rigid. The material  224  disposed within the flexible shaft  223  may be an epoxy-type glue, a low melting temperature metal with an electric heating wire  225  disposed therein, a fine granular material or known chemicals which become semi-solid upon exposure to light, heat, or chemical means. Where a fine granular material is used, a mechanical compression fixture  226  or vacuum suction may be provided to compress the material  224  to cause the shaft  208  to become rigid. 
   Referring to  FIG. 45B , additionally disposed within the flexible shafts  223  may be a plurality of interconnected discs  227  which are substantially parallel and which engage the inner-surface of the flexible shaft  223 . As with the above-described embodiments, the discs  227  may be interconnected by a wire  210  running the length of the shaft. The plurality of discs  227  reduce shear forces across the flexible shaft  223  and may provide separately activated sections that provide for selective stiffening of the flexible shaft along its length. As would be apparent to one of ordinary skill in the art, a flexible lockable shaft may be provided by a hybrid of the various embodiments described herein, such that selective portions of the shaft may be rendered more or less flexible as desired. 
   Referring to  FIG. 46A , an adjustable shaft means  3  may also be provided by a plurality of adjustable links  228  that are connected to, or comprise, the shaft means  3 . Preferably, the adjustable links  228  are positioned at the distal end of shaft means  3  and are connected to the connecting shaft  2 , or directly to the contact members  1 . Referring to  FIG. 46A , a plurality of curved or bent links are provided, preferably at least three such links, which are independently adjustable to provide multiple rotational adjustments. The plurality of adjustable links  228  provides a compact mechanism for positioning the contact members  1  throughout a wide range of motion. 
   Referring to  FIG. 46B , the links are independently rotatable relative to the shaft means  3  and the shaft  2  connecting end contact members  1  and to each other. The assembly formed, of the plurality of connected links may be lockable by providing an elastomeric liquid or gas shredded elastomer rubber, granulated plastic, or tint rubber metallic ball bearings hydraulic medium within the body of the links  228 . 
   Referring again to  FIG. 46A , an elastomeric hydraulic medium  229  is disposed within the adjustable links. The point of interconnection between the adjustable links may have internal or external retaining rings  230   a ,  230   b  and a means for compressing the elastomeric hydraulic medium  229  that is operably associated with the interior of the adjustable links  228  such that a force can be exerted on the medium  229  to pressurize the medium to lock each link  228  against the retaining rings  230   a ,  230   b  to fix the position of each adjustable link  228  relative to the adjoining link, thereby locking the entire assembly of the shaft means  3  into position. 
   Referring to  FIG. 46C , a means for compressing the elastomeric hydraulic medium may be provided by a pushrod  231  that encounters the medium at its distal end, and which may be actuated by a handle  233  attached to a screw  232  at the proximal end of the shaft means  3 . The handle  233  has a spring  234  disposed about a piston to maintain a constant small force upon the medium  229 . The compression spring  234  in the proximal end of the shaft  3  provides a minimal preloaded force on the pushrod  231  in the same direction as when the handle engages the pushrod with screw  232 . The force provided by spring  234  allows repositioning of the contact members  1  in a non-locked state. Additionally, the handle  233  is threaded into a housing  236  which is in turn threaded onto the shaft  3 . Rotating the housing  236  on the threaded shaft  3  provides for an adjustment in the length of the shaft which in turn will adjust the preload force that the above-mentioned spring maintains, as well as, the axial position of the handle  233 . 
   A flexible shaft may also be provided by the embodiment of  FIG. 47  having a plurality of substantially unstretchable strands  239  contained within a flexible outer shaft  240  that has a locking means comprised of clamp  241  at the proximal end for compressing the strands  239  at the proximal end and thus fixing the position of the flexible shaft. Thus, by actuating the locking means comprised of clamp  241  the strands  239  within the flexible shaft  240  are compressed against one another, preventing an individual strand from sliding relative to one another, thereby fixing the position of the plurality of strands  239  and locking the contact members  1  in place. 
   The interior of the flexible shaft  240  may be provided with several flexible substances which may be rendered solid by chemical or mechanical means or may have sealed portions that cause the flexible shaft  240  to become rigid or semi-rigid. For example,  FIG. 48  has a flexible shaft  240  with a cable  210  running along its length and plurality of fluid-filled lumens  242  disposed therein. When the lumens  242  are not sealed, the contact members  1  may be continuously positioned and the flexible shaft  240  set in any configuration. When the desired orientation of the contact members  1  is achieved, the lumens  242  are sealed to fix the position of the flexible shaft  240 . Additionally, these lumens  242  may be differentially pressurized or evacuated to adjust the position of contact members  1 . 
   Referring to  FIG. 49 , a fine adjustment mechanism is provided by a plurality of threaded positioning cables  248  that traverse threaded ports  244  of a proximal portion  243  of the shaft means  3  and about the periphery of an end member  245  of the shaft. The end member  245  of the shaft  3  is positioned at each of the plurality of threaded ports  244  by turning the threaded cables  246 . By rotating the cables by knobs  247 , the portion of the end member  245  of the shaft is moved either upward or downward relative to its original position. 
     FIG. 50A  shows the interior of a shaft means  3  of the invention having a spring-loaded mechanism  249  in the proximal portion thereof for damping the vertical motion of the proximal end of an inner shaft  251 . A spring  252  is mounted within the interior of the proximal portion  253  of an outer shaft  254  such that when the contact members  1  are lowered onto the beating heart, the proximal end of inner shaft  251  gently compresses the spring  252 . The outer shaft  254  may be positioned downward until a point of resistance is met at which the beating heart achieves adequate stabilization. At that point, the outer shaft  254  may be fixed in position, i.e., by attaching to the retractor or other stabilized support  255  while the inner shaft  251  may move up and down in a vertical direction. The oscillation of the inner shaft  251  is dampened by the spring  252  mounted in the proximal portion  253  of the outer shaft  254  or may be rendered motionless by lower positioning of the outer shaft  254  relative to the surface of the beating heart. 
   As shown in  FIG. 50B , the spring mechanism  249  may also be mounted at the distal portion of the shaft means  3  and the spring  252  may be external to a central shaft  256 . An additional configuration having a damped vertical motion is provided by a fluid-dampening mechanism consisting of a chamber  257  having a plunger  258  for moving therein wherein said plunger has a piston  261  having an annular seal  261   a  thereabout, such as a rubber O-ring seal, that engages the internal portion of the chamber  257  to substantially seal the passage of fluid. Piston  261  has one or more orifices  269  to restrict the flow of fluid therethrough. Additionally, inside plunger  258  is a one-way valve such as a spring-loaded ball  258   a  within a bypass passage  258   b . As an upward vertical force is imparted upon the central shaft  250 , the fluid dampening mechanism restricts the ability of the central shaft  250  to move upward, while its downward motion is relatively unrestricted, due to fluid flowing through bypass passage  258   b.    
   Referring to  FIG. 51A , the shaft means  3  depicted therein has an adjustable central shaft  263  with a fine adjust capability provided by a thumbscrew  264  which is rotatable about a threaded portion  265  of the central shaft  263  and which is connected at the most distal end to the contact members  1 . Independent rotation of the central shaft  263  is prevented by a stop  268 . As in  FIG. 1 , the shaft of this embodiment may be rotatably attached to a portion of a retractor or stabilized support  266  by passing the shaft through a ball and socket joint  267 . 
   Referring to  FIG. 51B , the contact members  1  are attached to a partial portion of the shaft means  3  comprised of an outer sleeve  269  that extends to engage a second shaft  270  having a plurality of splines  271  about the exterior. A first internal shaft  272  is attached to a ball joint  273  operably connected to the contact members  1 . The first internal shaft  272  is disposed inside both the outer sleeve  269  and the second shaft  270  and has threads  274  to permit adjustment by a handle  275  (which may be removable). At the end of the threaded internal shaft  272 , the ball joint  273  allows the contact members  1  to rotate at the base of the shaft means  3 . The second shaft  270  is engaged through the outer sleeve  269  by the splines  271  to keep the ball joint  273  from rotating. A circular clip  276  has inner ridges  276   a  that pass through the outer sleeve  269  and maintain the ball joint  273  in a fixed position. 
   Referring to  FIG. 52 , a method for providing continuous and adjustable positioning of the contact members  1  of the invention may be readily provided by a malleable shaft  277  which is attached to the contact members  1  and which may slide and be molded by hand. In particular, the malleable shaft  277  may slide through a fixture  278  attached to a stable support such as a retractor blade  279  used to open the surgical incision. The vertical positioning of the device may be achieved by a handle  280  which is manipulated from outside of the incision and causes a vertical portion  281  of the malleable shaft  277  to slide through the fixture  278 . 
   Referring to  FIG. 53 , an embodiment for the shaft means  3  of the invention is shown having a plurality of linked members  282 , each of which is connected to the adjacent linked member  282  by a hinge  283 , and a torsion spring connected to each hinge (not shown) and which are interconnected by a cable  284  connected to each linked member  282 , preferably at an attachment point  285  adjacent to the hinges  283 . By providing a plurality of discrete interconnected linked members  282  with an arcuate shape, and by providing an interconnecting cable  284 , a curved shaft means  3  is provided with the ability to coil and uncoil as the tension is exerted, released, or reversed, on the cable  284 . Preferably, the most distal linked member  282  and the end of the cable  284  are affixed to contact member(s) in any of the several embodiments described previously. 
   To take advantage of the minimally invasive procedures enabled by the invention, the positioning of the contact members  1  by manipulation of the configuration of the shaft means  3  may be achieved remotely, i.e., from outside the incision, by any of a variety of mechanisms attached to and operably associated with the shaft means  3 . Referring to  FIGS. 54A through 54C , remote manipulation of the positioning of the contact members  1  may be provided by a shaft means  3  having a ball joint  286  at the distal end thereof which is connected to the contact members  1  or the connecting shaft  2 . Continuous positioning of the ball joint  286  may be provided by a plurality of cables  287  which are affixed to the ball joint at opposing points  288  at the exterior surface of the ball joint  286 . The ball joint  286  is maintained in a socket  289  at the distal end of the shaft means  3 . The shaft means  3  itself may be rigid or flexible, or may be fixed into a pre-determined position by the surgeon depending on the clinical environment. Additionally, the shaft means  3  may be comprised of a plurality of shafts, including an inner flexible shaft  290  contained within a rigid shaft  291  wherein the flexible shaft  290  extends above the rigid portion, terminating at the positioning handle  292 . The contact members  1  are positioned by means of the plurality of cables  287  attached to the ball joint  286 . The plurality of cables  287  runs from the ball joint  286  through the length of the shaft means and terminate in a positioning handle  292  at the proximal end of the shaft means  3 . The shaft  3  may be of any convenient length but is preferably long enough to extend the positioning handle  292  to a point sufficiently beyond the incision that manipulation of the position of the contact members  1  does not interfere with the surgeon&#39;s ability to visualize the surgical site. Thus, each cable  287  has a distal portion affixed to the ball joint  280 , and a proximal portion affixed to a positioning handle  292  having the cables attached thereto. In one configuration, the plurality of positioning cables  287  are affixed about a plurality of attachment points  293 , respectively, on the positioning handle  292 . 
   In the embodiment of  FIGS. 54B and 54C , the positioning handle  292  has a recessed area  295  in the bottom surface and a post  294  disposed in the recessed area  295  about which the cables  287  are affixed at several points. The most proximal portion of the positioning handle  292  is adapted to be grasped by the hand and may be rotated about the post  294  to provide selective tension on the cables  287 , thereby repositioning the contact members  1  at the distal end of the shaft means  3 . 
   As is apparent from the foregoing description, an important function of a shaft means is to selectively place the contact members at the appropriate site on the beating heart, while providing sufficient flexibility and positioning adjustability for different clinical situations and for different surgical access techniques. Also, the shaft is typically mounted or attached to a stable support at a proximal end and typically at a point outside the patient&#39;s chest. Thus, it is advantageous to provide a shaft means having the ability to be positioned in several configurations, particularly relative to a stable support such as a surgical retractor or access platform which is used to provide access to the beating heart. 
   Referring to  FIGS. 55A and 55B , because the available access and working space for the surgeon may be limited, certain embodiments of the invention may be contained substantially within the chest cavity. Preferably, such a stabilizing means is connected to the rib retractor and may be affixed to one or both sides of the opening created by spreading the ribs using the rib retractor. 
   Referring to  FIG. 55A , rib retractor  296  is shown in an open position whereby blades  297  engage and spread the ribs. A pair of stabilizing bars  298  having a conventional ratchet means  299  attached at the end thereof are positioned beneath the retractor. The ratchet means  299  is comprised of a plurality of teeth  300  on the stabilizing bars  298  and a ratcheting aperture  301  permitting one-way passage of the stabilizing bars  298  unless released by a release mechanism. The stabilizing bars  298  are curved downward such that as the bars are advanced through the ratchet means  299 , the lowermost portion of the stabilizing bars  298  engages the beating heart  301   a  proximate to the anastomosis site. 
   Referring to  FIG. 55B , the orientation of the portion of the stabilizing means which engages the heart relative to the rib retractor  296  is similar to the embodiment shown in  FIG. 55A . In this embodiment, a contact member  1  is attached on opposite ends to at least two malleable supports  302  which are in turn attached to the rib retractor  296 . The malleable supports  302  are preferably made of stainless steel bands which are woven in a mesh or have a repeating serpentine configuration to allow for substantial extension into the chest cavity. This configuration yields a malleable support  302  with sufficient tensile strength to maintain a stabilizing force at the anastomosis site while allowing the surgeon to manipulate the malleable supports  302  within the chest cavity to achieve the desired orientation relative to the beating heart. 
   As noted above, at the upper end of the shaft means  3 , the shaft means  3  may be attached to a fixed support which may be any surface or structure which does not move with the beating heart. For example, the shaft means  3  may be attached to a fixture on the retractor system used to spread the ribs for access to the heart or may be attached to a fixed structure such as the surgical table or associated aperture which is not connected to the patient. In a preferred embodiment, the shaft means  3  is directly attached to a component of the retractor system which is designed to receive the shaft means  3  and to maintain the position and orientation of the shaft means  3  during the procedure. 
   Referring to  FIGS. 56A and 56B , an adjustable slide mechanism is provided to the shaft means  3  such that the shaft means can be continuously positioned relative to a retractor. For example, in  FIG. 56A , a curved shaft  303  traverses a ball joint  304  disposed at the end of an adjustable arm  305  which connects the shaft means to the retractor  306  and is lockable relative to the retractor  306 . The curved shaft  303  traverses the ball joint  304 , as described previously, and is positioned by sliding the shaft  303  relative to the ball joint  304 , providing the ability for the contact members  1  to be positioned at any point within a given arc as defined by the flexible shaft  303 . Also, the entirety of the curved shaft  303  may be positioned in a perpendicular direction away from the length of the retractor blade  307  using the adjustable arm  305 .  FIG. 56B  shows a top view from LVI-LVI of the adjustable arm  305  which may have a slot or groove formed in the body thereof allowing continuous positioning until the arm is fixed in position by a locking mechanism  308 . Thumbscrew  312   c  locks the position of ball  304  member in place. 
   In  FIG. 56C , the shaft means  3  is comprised of a pair of parallel shafts  309  and  310  which slide around an axle  311  disposed in a tightening mechanism  312  affixed to the retractor  313 . The position of the shaft means  3  relative to the retractor  313  is adjustable by sliding the shaft means  3  along the axle  311 . Moving handle  31  la causes a corresponding motion in the contact members  1 . Tightening thumbscrew  312   c  locks clamp members  312   a ,  312   b  onto port  312   d  and shafts  309 ,  310  simultaneously. 
   Referring to  FIG. 57 , an adjustable arm may be provided for continuously adjusting the distance between the retractor or other stable support and the shaft means of the means for stabilizing the beating heart of the invention. At one end of the adjustable arm, the shaft means  3  traverse a ball joint  314  which is contained in a socket  315  formed in the body of the adjustable arm. The tightness of the ball joint  314  may be adjusted by tightening a shaft  316  affixed to the socket  315  and which passes through the body  318  of the adjustable arm. The tightening shaft  316  which is in turn connected to a rotating knob  319  that may tighten or loosen the ball joint  314  by tightening the socket  315  via the tightening shaft  316 . The distance between the shaft means  3  and the ball joint  314  is also adjustable relative to the stable support  320  by virtue of a slit or groove  321  formed in the body of the adjustable arm. A locking mechanism  322  is disposed within the groove  321  such that actuating a locking handle  323  fixes the position of the adjustable arm by tightening the locking mechanism  322  about the groove  321 . 
     FIGS. 58A ,  58 B, and  58 C are multiple segment shaft means  3  having alternate configurations to permit adjustable positioning.  FIG. 58A  has an elbow joint  324  with a hinge attaching upper dual shaft members  325   a ,  325   b , and lower dual shaft members  326   a ,  326   b , such that the upper and lower shafts members are continuously positioned relative to a retractor or other stable support  327 . The assembly may be attached to the retractor and the lower dual blade shaft members  326   a ,  326   b  are attached to the contact members, by rotating joints  328  while the upper dual shaft members  325   a ,  325   b  are attached to the support by a second rotating joint  329 .  FIG. 58B  has two shafts which are positioned to extend in a horizontal plane by extending from beneath a retractor blade  330  and by rotating around at least one circular joint  331  disposed between a first and second shaft  332  and  333 . At the end of the second shaft  333 , the contact members  1  may be provided with a third vertical shaft  334  having a ball joint  335  disposed at a proximal end thereof and which is affixed to the second shaft member  333 . 
   One particularly useful feature of the shaft means of the invention is the ability to extend the distal end of the shaft in a continuous or telescopic fashion such that the contact members can be continuously positioned downwards relative to the proximal end of the shaft that is in turn attached to a retractor or other stable support. The degree of downward extension may be provided by several mechanical embodiments,  FIG. 58C  is a telescoping shaft member  336  having a lower shaft  337  concentrically oriented within an upper shaft  338  and a locking means  339  for fixing the position of the lower shaft  337  relative to the upper shaft  338 . Additionally, the contact members  1  may be positioned by pivot  339  located at the distal end of the lower shaft  337 . The upper shaft  338  may also be positioned relative to the retractor blade  330  by a tilting mechanism  340  that adjusts the angle of the upper shaft  338  relative to the retractor blade  330 . 
   Referring to  FIGS. 59A ,  59 B, and  59 C, the stabilizing means of the invention may be provided by a plurality of adjustable attachments that affix the proximal end of a shaft or shafts to a retractor. For example, in  FIG. 59A , a plurality of telescoping shaft means  341  are affixed to several pivoted joints  342  or hinges on a retractor blade  343  such that the contact members  1  can be continually positioned in three dimensions relative to the retractor blade  343  which grips one edge of an incision. When retracted, the contact members  1  are contained entirely within a recessed housing  343   a  formed in the retractor blade  343 . 
   In the embodiment of  FIG. 59B , a lockable rotatable arm  344  is provided that may be locked or unlocked to be positioned vertically by a first hinge  345  and to swing or rotate around a second hinge  346  wherein both hinges are mounted in a retractor arm or a retractor blade  343 . 
   In  FIG. 59C , the shaft means has an adjusting knob  347  affixed to the proximal end of a telescoping shaft means  348  at a point along the retractor arm  349  or the retractor blade  343 . By loosening the adjusting knob  347 , the telescoping shaft means  348  may be extended or retracted relative to the retractor arm  349  and the retractor blade  343  thereby allowing the contact members  1  to swing into position to be brought into contact with the beating heart. 
   In the embodiment of  FIG. 60 , a flexible central shaft  350  having a handle  351  at the most proximal end is disposed within at least one shaft guide  352 , and preferably a series of shaft guides  352 ,  353 , and  354 . The handle  351  is adapted to be held by the hand and allows both rotation of the flexible central shaft  350  and positioning of the contact members  1  by extension or retraction of the handle  351 . Any of the series of shaft guides  352 ,  353 , and  354  may be straight or formed to have a predetermined curve to alter the direction of the central shaft  350 . A proximal shaft guide  354  may be integral with a retractor  355  used to open a surgical incision. A particularly preferred low profile embodiment of  FIG. 60  has a shaft guide  354  integrally associated with a cross-member  356  that connects the arms of retractor blades  357 . The shaft means  3  at the distal end of the central shaft  350  may be straight or curved and rigid or flexible as desired. To fix the position of the central shaft  350 , a lock mechanism  358  is provided, preferably at a proximal portion of the central shaft  350 , to fix the position of the central shaft relative to the shaft guides  352 ,  353 , and  354 . 
   Referring to  FIG. 61 , as noted above; attachment to a rib retractor is a preferred technique for fixing the position and orientation of the stabilizing means. The stabilizing means of the invention may therefore advantageously be attached to a fixture attached to a rib retractor  359  or may be configured to be directly incorporated into the body of a portion of the rib retractor  359 . A surgical rib retractor  359  is generally comprised of a body  360  having blades  361  attached thereto, which engage the ribs and spread the ribs when the retractor  359  is operated to move the blades  361  apart from one another. The space created by the retracted blades  361  provides access to the heart. Thus, once the retractor  359  is locked into the open position, the stabilizing means may be applied to the heart and a stabilizing force maintained at the site of the anastomosis by fixing the position and orientation of the shaft means  3  relative to the rib retractor  359 . Referring again to  FIG. 61 , the shaft means  3  may traverse the width of the body  360  of the retractor  359  and is held in place by an upper plate  362  and a lower plate  363  having circular openings  364  therein through which the shaft means  3  passes and which maintain the position of a sphere  365  positioned between the upper plate  362  and lower plate  363 . The size of the openings  364  is larger than the diameter of the shaft means  3  but smaller than the largest diameter of the sphere  365 . Thus, the shaft means  3  passes through the sphere  365  and may pivot about a point approximately at the center of the sphere  365 . 
   Referring to  FIG. 62 , the stabilizing means of the invention may be provided by a shaft means  3  that extends from a cross-arm  366  connecting the individual arms  367  of a surgical retractor such that the shaft means  3  extends between the arms  367  attached to the retractor blades  368  and below the level of the retractor blades  368  such that the contact members  1  and separate shaft  369  is positioned beneath the level of the retractor blades  368  and is generally contained within the chest cavity. This embodiment is a low profile design wherein a portion of the shaft means  3  extends into the chest cavity and has a second substantially horizontal shaft  369  extending from the distal end  370  thereof. 
   Referring to  FIG. 63 , the stabilizing means of the invention may advantageously be provided with a rib locking mechanism  371  affixed to either side of a rib  372  to form a stable support for shaft means  3  that extends from the rib locking mechanism  371  into the chest cavity. The rib locking mechanism  371  is comprised of an adjustable post  373  preferably disposed within a slot  376  formed in the body of the rib locking mechanism  371  and is positioned between two adjacent ribs  372 ,  373  and a blade  374  affixed to the opposite side of the rib  372  most adjacent to the incision. The position of the blade  374  is adjustable relative to the post  373  by sliding the mechanism  371  along the slot  376  and fixing it in place with a locking latch  373 . 
   As noted herein, the embodiments of the stabilizing means of the invention may also be used to position the heart to facilitate performing the bypass surgery or any other cardiac procedure where the position of the beating heart may be adjusted. Referring to  FIG. 64 , the embodiment of  FIG. 63  may be utilized as a heart positioning device requiring only the modification that the shaft means  3  affixed to an identical or equivalent rib locking mechanism  371  and the contact members  1  have a length and tensile strength such that the contact members  1  can be maintained in a position about the periphery of the beating heart as desired. 
   In combination with the several designs for contact members and related features described previously herein, the configuration and construction of the element which is attached to the contact members principally the shaft means, may partially comprise the contact members and may be provided in several alternative designs without departing from the spirit of the invention. As indicated previously, certain variations may depend on the surgical demands of a particular procedure, and will depend on the nature of the surgical incision(s) used to access the beating heart. For example, some embodiments of the invention are particularly useful where a minimally invasive incision is created, and the procedure is performed by introducing instruments through a cannula or a hollow shaft that provides access to the heart.  FIGS. 65A through 65D  show an embodiment of the invention whereby a means for stabilizing the beating heart is provided that is integral or closely associated with a hollow shaft  386  that defines a surgical field around the site of the anastomosis. In  FIG. 65A  a hollow shaft  386  is provided having a lower cylindrical portion  387  that splits into two semi-cylindrical portions  388   a  and  388   b  that define the surgical field for an anastomosis of a target vessel  389 . 
   Preferably, the bottom surface  390  has an opening  391  through which the vessel  389  passes such that the vessel lies within the opening  391  and within the larger space created by splitting of the hollow shaft  386  to create the surgical field. In this embodiment, instruments may be introduced either through the hollow shaft portion  386  of the device or through the split portion of the lower portion  387  of the shaft to provide stabilization and access to the vessel  389 . The opening action of the lower portion  387  of the shaft may be provided by a rotating shaft means  3  which, when rotated, forces the lower portion  387  to split into the semi-cylindrical portions  388   a  and  388   b.    
   Referring to  FIG. 65B , a unitary hollow shaft  392  may be provided that contacts the beating heart about the bottom surface  390 , to provide the stabilization function, and has a plurality of openings  393  disposed in the body  394  thereof. Preferably at least one passage  395  is provided in the bottom surface  390  such that the target vessel  389  may be disposed within the passage  395 . A second passage  396  may be provided in the bottom surface  390  of the unitary hollow shaft  392 , preferably at an opposite end, such that the vessel may pass through the openings  395 ,  396 , or where a single opening is provided (not shown) the edge of the bottom surface opposite the opening  395  acts as an occluder. Larger openings  393  in the body of the unitary shaft  392  may be provided to enable the surgeon to have access to the target  389  vessel through the body of the unitary shaft  392 . 
     FIG. 65C  is a hollow shaft element  398  having formed therein a pair of contact members  1  of the type described previously, but which fold out from the body  399  of the shaft by virtue of a hinge or pivot  400  at the lower portion  401  of the shaft element  399 . By folding out the contact members  1 , which are maintained substantially integral to the shaft element during insertion of the shaft element  398  through a surgical incision, the contact members  1  engage the surface of the beating heart and provide the stabilization function. The surgeon may introduce instruments through the hollow portion of the shaft element  398 , or from another direction to achieve the anastomosis. 
   Referring to  FIG. 65D , the application of the stabilizing force need not be applied directly below the surgical field created by the shaft element  398 . The embodiment of  FIG. 65D  has an annular ring  402  formed in the bottom portion  391  of the shaft element  398  and that may rotate about the axis provided by a rod  403  or the shaft means  3  passing through the wall of the shaft element  398 , and which is affixed to the annular ring  402 . By rotating the rod  403 , the annular ring  402  rotates out from under the bottom  391  of the shaft element  398 , and may be positioned to contact the surface of the beating heart in an annular fashion adjacent and tangent to the shaft element  398 . As with other embodiments described herein, the annular ring structure  402  that applies the stabilizing function may have at least one passage  464  formed in the bottom surface such that the vessel  389  may be positioned therein. The passage  464  may pass through the entirety of the ring  402  making it a “C” or “V” shaped contact member (not shown), which will allow easy removal from the field after construction of the anastomosis fastening the graft to the heart. Alternatively, the ring structure  402  may be cut or broken for removal if necessary. 
   Referring to  FIG. 66 , this embodiment of the stabilizing means is comprised of an elongated sheath member  405  which wraps around the heart in a strap-like fashion to restrict the motion of the heart. This embodiment may be used with a thoracotomy providing surgical access, but is particularly useful when access to the beating heart is provided by a sternotomy. The sheath member  405  is positioned to surround the heart and manipulated so that each end of the sheath member  405  extends out of the chest cavity through the sternotomy. If desired, at least one end of each sheath member  405  is attached to a retractor  406  to secure the position of the sheath member  405 . The sheath member  405  may have a plurality of support attachments  407  which engage the exterior of the heart to hold it in place. At the point where the support attachments  407  contact the surface of the heart, the support attachments  407  may have friction means  4  (not shown) attached to the surface which is in direct contact with the heart. The support attachments  407  may have or be comprised of fluid-filled members  408  which cushion the heart against the sheath member  405 , and absorb the motion of the heart while it is stabilized. Where the sheath member  405  has one or more fluid-filled members  408 , the sheath member  405  may also include at least one lumen  409  for introduction of air or a biocompatible fluid to the inflatable members  408 , which may be inflated separately or simultaneously. In the former instance, a separate lumen  409  is provided for each inflatable member  408 . The insertion of the sheath member  405  into the chest cavity may be performed while the inflatable members  408  are deflated and is achieved manually or by a conventional guide and/or guide wire. Each of the support attachments  407  may be permanently attached to the sheath member  405  or may slide along the length of the sheath member  405 . Alternatively, alone or in combination with other inflatable members, the inflatable member  408  is positioned immediately proximate to the target coronary artery to achieve a more localized stabilization. Thus, the inflatable members of the invention may lie next to, or may surround, the heart of the target coronary artery and may have openings or apertures placed in the body thereof through which surgical procedures are performed. An additional stabilizing force may be applied when the inflatable member  408  fills the space between the heart and the enclosing structure, such as the pericardial lining or the back of the ribs. When the inflatable member  408  is appropriately inflated, the target artery site may be pressed against a proximate stabilizing structure, such as contact member  1 , the back of edge of the surgical incision. The fluid-filled or inflatable cushioning, stabilizing, or positioning means could also be applied via a rigid, malleable, deformable, or removable shaft, handle, mounting, or inflation means. 
   Similarly, referring to  FIG. 67 , a strap  410  may be provided which is arranged to pass over opposite retractor blades  411 , to pass underneath the heart, and which may be mounted at both ends to a crank  412  for selective movement of the strap  411 . By turning the crank  412 , or by otherwise manipulating the position of the strap  411 , the heart may be rotated for selective positioning or to provide access to various regions of the heart. The cranks  412  are advantageously attached to the retractor used to maintain spreading of the ribs in a minimally invasive thoracotomy. 
   As noted above, in addition to stabilization of the beating heart, the devices and methods of the invention may be used as shown in  FIGS. 66 and 67  to selectively position the heart. Additionally, an alternate to a continuous strap  410  is shown in  FIGS. 68A ,  68 B, and  68 C and is comprised of a substantially flat, flexible sheet  413  positioned under the heart. One side of the sheet  413  may have a hydrogel  414  coating, or a coating of a similar material that adheres to the epicardial surface. Preferably, the other side of the sheet  413  is smooth. In a preferred embodiment, two sheets  413  are joined at their respective edges to form an interstitial space (not shown) therebetween. Perfusion of the interstitial space with fluid softens the hydrogel  414 , allowing ready repositioning or removal of the sheets  413 . 
   Depending on the nature of the surgical procedure, it may be desirable to lock the contact members  1  in place by manipulating their position from a location remote from the surgical field. In the embodiment of  FIG. 69 , a plurality of telescoping shafts  415  are provided which engage a contact member  1  at their most distal end. Preferably, each telescopic shaft  415  is affixed to a point on the retractor blade  416 , thereby allowing the telescopic shafts  258  to be collectively adjustable to position the contact members  1  at any point within the range of movement of the telescoping shafts  415  within the surgical field. At the most proximal point of each telescopic shaft  415 , the shaft is affixed to the retractor blade  416  by virtue of a hydraulic actuator  417  that fixes the orientation of each telescopic shaft  415  relative to the retractor blade  416 . Each hydraulic actuator  417  is attached to a lock valve  418  via non-expanding hydraulic hoses  419 . Typically, the lock valve comprises a reservoir  420  and a hand-activated switch  421  for closing the lock valve  418  to lock the hydraulic actuators  417  into position. Any number of telescopic shafts  415  may be provided, however, it is preferable that a plurality of mounting points are available at various locations on the retractor blade  418  such that the surgeon can individually attach several, preferably at least three, telescopic shafts  415  to the retractor blades  416  at the locations best suited for each surgical procedure. 
   Referring to the embodiment of  FIGS. 70A through 70D , a stabilizing means is provided with a shaft means  3  comprised of a plurality of arms connected by joints having selectively placed friction surfaces associated therewith that freeze the joints and adjustable arms into a set configuration when the contact members are displaced upwards by the motion of the beating heart. Referring to  FIG. 70B , the retractor blade  416  has a locking mechanism  422  with an internal cam shaft  422   a  actuated by a handle  422   b  that expands a first curved leaf spring  422   c  to fix the position of a first shaft  424  relative to the retractor blade  416 . As shown in  FIG. 70A , the first shaft  424  is attached to a first friction joint  425  permitting rotation of the joint about an axis perpendicular to first shaft  424 . Referring to  FIG. 70C , the friction joint  425  is comprised of a lower housing  426  affixed to the first shaft  424  and an upper housing  427  affixed to a second shaft  428  which may be a discrete cylindrical shaft as the first or may be an extension of the housing of the friction joint  425 . A ball pivot  429  is positioned between the upper  427  and lower housing  426  to allow the individual housings to rotate about each other. Either the upper  427  or lower  426  housing has disposed therein a friction surface  430 , and the opposite housing has a friction engaging means such as teeth  431 . When either housing is displaced by tilting about the ball pivot  429 , the friction surface  430  contacts the friction engaging means  431  and freezes the position of the friction joint  425 . The second shaft may be connected to a second friction joint  432  having an equivalent construction to the first. 
   Referring to  FIGS. 70A and 70D , a rotatable shaft means  433  is comprised of a central rod  434  disposed within a housing  438  having a ratcheting mechanism formed from tongues  435  engaging teeth around said central rod  434  to fix the rotatable position of the rotatable shaft means  433 . The rotatable shaft means  433  is connected to the contact members  1 , for example, by a hinge  436  having a shaft  439  resistant to rotation by teeth (not shown) engaged by molded tongues  437 . 
   In the embodiment of  FIGS. 71A through 71D , a retractor blade  440  is adapted to receive a clip into which is inserted a flexible slide having a contractible shaft means at the distal end thereof and means for extending the contractible shaft. Referring first to  FIG. 71C , the assembly includes a C-shaped clip  441  for attaching the stabilizing means to the retractor blade  440 . The clip has at least one lip  442  adapted to fit within a guide  443  formed in the retractor blade  440 . The body of the clip  441  also has a slot  444  around the outside of the curved portion as shown in  FIGS. 71A and 71B  and in phantom in  FIG. 71C  for insertion of a flexible slide  445 .  FIG. 71D  shows the flexible slide  445  that fits inside the slot  444  formed in the clip  441  such that the flexible slide enters the clip  441  through the slot  444  and curves around to conform to the shape of the clip  441 . A block  440  is mounted at the distal end of the flexible slide  445 . 
   An extendable shaft means  447  is attached to the block  446  and has an unexpandable hydraulic tube  448  affixed thereto which is in fluid connection with a syringe  449  or other such fluid containing apparatus to apply hydraulic pressure through the tube  448  to extend the shaft means  447 . Preferably, the syringe has a one-way valve  450  with a release valve  451  such that hydraulic fluid pressure is applied to progressively advance the extendable shaft means  447 , while the one-way valve  450  prevents the extendable shaft means  447  from contracting. Upon completion of the procedure, the hydraulic pressure is released by activating release valve  451 . 
   Referring to  FIG. 71A , the surgeon would first insert the clip  441  onto the retractor blade  440  by inserting the flexible slide  445  into the slot  444 . The flexible slide  445  is thereby advanced from the top of the clip  441  through to the bottom until the extendable shaft means  447  is in position to be extended to bring the contact members  1  into conforming engagement with the heart. With one hand, i.e., via the syringe  449 , fluid is injected into the extendable shaft  447  to cause the contact members  1  to engage the heart. Note also that the guide  443  in the retractor blade  440  may extend the length of the blade  445 , allowing selective positioning of the clip  441  along the blade  440 . 
   Referring to  FIG. 72 , the means for stabilizing the beating heart of the invention is shown in use together with a rib retractor  452  and additional apparatus  453 ,  454  which may be used during the beating heart CABG procedure. In use, the blades  455  of the retractor separate the ribs, thereby providing an access space for the introduction of surgical instruments, including the stabilizing means of the invention. The stabilizing means is thus brought into contact with the heart such that the contact members  1  are proximate to the target artery  456 . A stabilizing force is exerted in an amount sufficient to minimize the motion of the beating heart, including fixing the stabilizing means in place, preferably by attachment to the rib retractor  452 . 
   Referring to  FIG. 73 , the stabilizing means is comprised of a pair of rectangular, substantially planar contact members  1 , which are placed proximate to a target artery  456 . The shaft means  3  is conformable such that it may be conveniently attached to the rib retractor  452 . As shown in  FIG. 73 , the surgeon may readily adjust the orientation and positioning of the connecting shaft  2  and the contact members  1  relative to the shaft means  3  while the stabilizing means is in continuous contact with the heart by manipulating the thumbscrew  457  at the proximal end of the instrument.  FIG. 74  shows a later stage of the procedure at a point where the anastomosis is being completed by suturing at target artery  456 . The stabilizing means thus maintains a stabilizing force at the anastomosis site for the duration of the procedure. 
   As described above in several embodiments of the invention, the stabilizing means may advantageously be integrated with a related surgical device such as a retractor that is used to spread the ribs in preparation for the cardiac surgery.  FIG. 75  is an embodiment of the invention having a pair of shaft means  3  integrated with the arms of a retractor  459  suitable for spreading the ribs in a minimally invasive cardiac surgery. The stabilizing means are comprised of shafts having adjustable links  459  as previously described that provide for positioning of the contact members  1 . The shaft means  3  also traverse ball joints  460  that are directly affixed to the arm  458  of the retractor blade, and terminate with adjustable handles  460  for locking the position of the shaft means  3  and contact members  1  in place. 
   Referring to  FIG. 76 , a further embodiment of the means for stabilizing the beating heart of the invention is illustrated solidly attached to an arm  463  of a rib retractor  464  via a quick-locking base means which allows exceptional maneuverability in the orientation and placement of the contact member  1 . In addition auxiliary surgical instruments  465  consisting of, for example, a grasper, positioner, light, blower, suction device, etc., may be attached to a second arm  466  of the retractor via, for example a deformable wire  465 ′ and dovetail/clamping means similar to means  470 ,  474  described below. This allows for interchanging the positions of the stabilizing means and the auxiliary surgical instruments as desired. In accordance with the invention, the stabilizing means is comprised of several closely cooperating parts, which includes a quick-locking base/shaft lock mechanism  467 , an elongate shaft means  3 , a quick-locking handle mechanism  468  and a heart contact member  1 . The stabilizing means and means for mounting the stabilizing means to the retractor arm via in part the base/shaft lock mechanism  467 , provide a combination in which the shaft means  3  of the stabilizing means can be quickly rotated and translated along several degrees of freedom. Once the contact member  1  is correctly positioned to exert the stabilizing force on the heart desired by a surgeon, the stabilizing means may be quickly and solidly locked to the retractor arm  463 , and the contact member  1  is also solidly locked in position against the heart. The stabilizing means is just as quickly and easily removed from its position after surgery. Thus the combination of the invention depicted generally in  FIG. 76  provides an extremely solid heart stabilizing means which has the added advantages of very quick locking and unlocking mechanisms, wherein the shaft means and stabilizing means in general are locked in position by respective locking mechanisms such as, for example, screw means, cam lever means, etc. In addition, the stabilizing means and base mechanism configuration may be sturdily manufactured from plastic rather than metal materials, thus facilitating the manufacturing process. Also, the base/shaft lock mechanism  467  always remains out of a surgeon&#39;s way, at the margin of the surgical field while still allowing the contact member  1  to be positioned at any position and at any angle within the entire surgical field. 
   It is to be understood that the stabilizing means of the present invention may be solidly secured to a platform other than the retractor  464  such as, for example, a rail structure on the surgical table (not shown), a cannula secured between adjacent ribs as disclosed in  FIGS. 13A-13E ,  14 , etc. Thus, the quick-locking and readily maneuverable configurations of the present invention are readily adaptable to such alternative supporting platforms which would replace the retractor. In addition, the mounting configuration of the embodiments of  FIGS. 76-81  may be used with other stabilizing means embodiments of previous description hereinabove. 
   Referring to  FIG. 77 , the base/shaft lock mechanism  467  is shown in exploded view thereby further illustrating the base means by which the stabilizing means is attached to the retractor arm  463 . In this specific example, the retractor arm  463  (as well as the arm  466  of  FIG. 76 ) is modified to include a base supporting pedestal, herein exemplified by a generally rectangular male dovetail member  470  formed in the upper surface thereof. A locking notch  471  is formed in the pedestal (hereinafter referred to more particularly as the dovetail member  470 ) and provides means for locking a base  472  ( FIG. 76 ) for holding the auxiliary surgical instruments of previous mention such as the grasper  465  of  FIG. 76 . The notch  471  is not necessary and is not used in attaching the base/shaft lock mechanism  467  of the stabilizer means to the dovetail member  470 , as is described below. 
   Referring in addition to  FIGS. 78 ,  79 ,  80  and  81  as well as  FIG. 77 , the base/shaft lock mechanism  467  includes a base  473  with a clamping means, herein exemplified by a generally rectangular female dovetail  474  which matches the size and configuration of the dovetail member  470  to allow the base  473  to be slid over the matching dovetail member. The base  473  is formed with a central opening  477  therethrough ( FIG. 81 ) thus providing a “stationary” and a “moveable” wall  475 ,  476 , respectively. It is to be understood that the term “wall” is used for purposes of description simplification. Functionally, the walls comprise “contact areas” which provide specific points or small areas of contact and thus pressure points with respective pedestals to enhance the solidity of the mounting mechanisms, as further described with reference to  FIGS. 78 ,  78 A,  79 ,  81 . A back wall  478  ( FIG. 79 ) extends to the bottom of the base  473  and acts as a mechanical stop when installing the base  473  on the dovetail member  470 . The “moveable” wall  476  is selectively detached in part from the base so as to pivot slightly about a generally horizontal axis  486  formed by a recess in the wall ( FIG. 81 ), whereby the lower portion of the moveable wall  476  is allowed to move towards and away from the stationary wall  475 . In use, the clamping means (hereinafter referred to more particularly as the dovetail  474 ) of the base is slid over the matching dovetail member  470  on the retractor arm until the back wall  478  meets the respective edge of the dovetail member  470 , thereby providing a solid mechanical stop for the base. A clamp lever  479  having a general U shape and formed of a spring material, includes inwardly bent ends  480  which act as a pivot axis for the lever. The walls  475 ,  476  include respective ramps  481 , with respective locking notches  482  integrally formed in the walls ( FIGS. 79 ,  81 ). The locking notches  482  include respective stops formed along their lower curvatures to prevent further downward movement of the clamp lever  479 . The pivot ends  480  of the clamp lever  479 , which is spring loaded inwardly, are inserted into coaxial holes  483  at the rear of the walls of the base  473 . After the base is in place on the dovetail member  470 , the clamp lever  479  is pivoted downward, whereby the sides of the lever bear against the ramps  481  to produce a gradually increasing force which drives the moveable wall  476  towards the stationary wall  475 . The clamp lever is locked in place once it snaps into the locking notches  482  in the ramps  481 . This action clamps the dovetail  474  of the base solidly on the dovetail member  470 , as more clearly shown in  FIG. 81 , and as further described below. Other means may be used to provide the clamping action which locks the base to the pedestal. For example, the clamp lever  479  may be replaced by a cam and lever on one wall with a rod attached between the cam and the opposite wall such that rotation of the cam via the lever draws the walls together to clamp them onto the pedestal. 
   The dovetail member  470  is formed on both of the retractor arms  463  and  466  and each includes the notch  471 . As previously mentioned, the notch  471  is not necessary for attaching the stabilizing means to either of the retractor arms since this embodiment of the invention employs the female dovetail  474  in the base  473  to provide a quick and solid locked condition. However, auxiliary surgical instruments or devices, which do not have the base  473  configuration, may be securely attached to the dovetail member  470  of either retractor arm utilizing a slide-on solid female dovetail  469  formed in the base  472 . See  FIG. 76 . A snap clip  487  is formed in the base  472  and includes a protruding tooth adapted to snap into the notch  471  when the base reaches full seating on the dovetail member  470  to lock the base in place. The base  472  is quickly removed by lifting the clip  487  to disengage the tooth from the notch  471 , whereupon the base is slid off the dovetail member  470 . In  FIG. 76 , the deformable wire  465  may be used to support various auxiliary surgical instruments such as those of previous mention in any desired position and angle within the surgical field. 
   Referring to  FIG. 81 , the confronting “horizontal” seating surfaces of the walls  475 ,  476  are formed at precise angles relative to the “horizontal” seating surfaces of the dovetail member  470 , such that only outermost portions  484 ,  485  of the horizontal seating surfaces of the base  473  and dovetail member  470 , respectively, actually make contact with each other. This provides, for example, four widespread and thus solid areas of seating contact between the base  473  and the retractor arm  463 , and thus a very solid base for supporting the stabilizing means. Furthermore, installation of the solid base is achieved very quickly with a simple pivoting downward of the clamp lever  479  until it snaps into locked position in the locking notches  482 . A recess  560  in the dovetail  474  ( FIG. 79 ) mates with a bump  561  in the dovetail member  470  ( FIG. 78 ) to prevent the base from backing out from the member  470  after being locked. 
   In addition, specific points or areas of contact between the slanted sides of the male dovetail member  470  and of the female dovetail  474  provide corresponding specific points or areas where pressure is applied by the clamping means, that is, the female dovetail  474 , against the male dovetail member  470 . To this end, referring to  FIG. 78A , a relief  562  in the slanted side of the dovetail member  470 , provides a pair of spaced-apart contact areas  563  on the respective side, which areas  563  engage the confronting slanted side of the stationary wall  475 . A slightly raised contact area  564  ( FIG. 79 ), which is beneath the ramp  481  in the moveable wall  476 , provides a single pressure point against the opposite slanted side of the dovetail member  470 . Thus, the combination of the opposing pair of pressure areas  563  and the single pressure area  564  provide a “ 3  point” contact between the female dovetail  474  and the male dovetail member  470 . This prevents any rocking motion, which contributes to the solidity of the base means mounting. 
   The base  473  is provided with a circular pedestal (hereinafter referred to as a male dovetail member  489 ) for attaching a shaft-locking support  490  ( FIG. 77 ) of the base/shaft lock mechanism  467  of the invention to the base  473 . However, before proceeding further, it is to be understood that the invention combination contemplates an embodiment wherein the detachable base  473  as described above may be replaced by a solid mounting means integrally formed on, for example, the retractor arm  463  or  466  or suitably secured to the railing of a surgical table or other platform. To this end, an upper-portion of the base  473 , namely the circular dovetail member  489  and the seating surfaces which support the member  489  and confront the bottom of the shaft-locking support  490 , may be formed on a retractor arm or other suitable platform. The shaft-locking support  490  then may be rotatably and detachably secured to the circular dovetail member  489 , as further described below. Thus, it is not intended that the detachable base  473  be the sole means for supporting the stabilizing means of the invention. 
   In addition, although the base  473  includes the clamping means, and the solid pedestal, that is, dovetail member  470 , is formed on the retractor arm  463  or  466  or other suitable platform, the positions of the complementary clamping and pedestal means may be reversed. That is, the bottom of the base  473  may include a pedestal or male dovetail member while the clamping means for locking onto the pedestal may be formed on the retractor arm or other platform. 
   The basic combination of the shaft-locking support  490  is illustrated in  FIG. 77  and includes an inner housing  491  and a complementary outer housing  492  adapted at their bottoms with a clamping means (hereinafter referred to as a female dovetail  493 ) whose diameter and configuration match those of the circular pedestal or dovetail member  489  of the base  473 . Referring also to  FIGS. 82 and 83 , the housings  491 ,  492  are provided with a coaxial central bore adapted to receive therethrough a cylindrical portion  494  of a shaft grip  495  in the inner housing  491 , and a combined screw  496  and knob  497  in the outer housing  492 . The screw  496  is adapted to threadably engage matching threads in the cylindrical portion  494  of the shaft grip  495 , to secure the two housings together, and when tightened to simultaneously solidly lock the shaft-locking support  490  in position on the base  473  by means of the circular dovetail  493  and circular dovetail member  489 . A shaft lock  498  is disposed within the shaft grip  495  and is adapted to apply a frictional surface against the shaft means  3  of the stabilizing means when the knob  497 /screw  496  are tightened to the shaft grip  495 . The same tightening procedure simultaneously forces the housings  491 ,  492  towards each other to thereby lock the housing dovetail  493  to the circular dovetail member  489 . 
   A compression spring  499  and a friction knob  500  may be coaxially disposed within a bore in the shaft grip  495  and combine to provide sufficient constant frictional contact against the outer surface of the shaft means  3  to hold the shaft means in place within a shaft-enclosing member  488  of the grip  495  when the knob  497 /screw  496  are not tightened such as when a surgeon is making adjustments to the stabilizing means. A selected number of annular stabilizer locking disks  501  are coaxially disposed about the cylindrical portion  494  of the shaft grip  495  and within the inner housing  491 , and act as a friction clutch mechanism to prevent horizontal rotation of the shaft means when the knob  497 /screw  496  is tightened to lock the stabilizing means. The details of the locking action and mechanisms therefore are further described relative to  FIGS. 82 ,  83 . 
   As mentioned, the shaft means  3  is confined in the shaft-enclosing member  488  of the shaft grip  495  as further depicted in  FIGS. 82 and 83 , in frictional contact with the shaft lock  498  and friction knob  500 , whereby the shaft means  3  may be rotated about a vertical third coaxial axis as well as translated up and down relative to the shaft grip  495 . In addition, the shaft means  3  and shaft grip  495  may be rotated as a unit in a generally horizontal second axis wherein the third axis is perpendicular to the second axis. Still further, the shaft means  3 , shaft grip  495  and support  490  may be rotated, that is, swiveled as a unit about a generally vertical first axis. Thus, the combination of the base/shaft lock mechanism  467  and shaft means  3  of the present invention allows four simultaneous directions of freedom of movement to facilitate orientation of the distal end of the shaft means  3 , and particularly the contact member  1 , relative to the patient&#39;s heart. Equally important, the present invention provides means within the base/shaft lock mechanism  467  for quickly locking the mechanism  467  and shaft means  3  in the selected orientation simply by tightening the single knob  497 , as described in  FIGS. 82 ,  83 . 
   The shaft means  3  is provided at its distal end with an improved embodiment of the contact member  1 , adapted for movement in all three dimensions to allow it flexibility in contacting a patient&#39;s heart. The proximal end of the shaft means  3  is provided with the handle mechanism  468  of previous mention in  FIGS. 76 ,  77 , which includes an angled handle  503  rotatably secured to the proximal end of the shaft means, and a knob  504  for locking the handle  503  and contact member  1  to the shaft means  3 , as further described in the  FIGS. 87-91 . In general, a partial rotation of the knob  504  causes a slight translation of a pushrod  505  within the shaft means  3  which, in turn, solidly locks the contact member  1  in the orientation selected by the surgeon, as further described below. 
   Referring now to  FIGS. 82 ,  82 A and  82 B, the base  473  and the shaft-locking support  490  are illustrated in further detail, with the circular dovetail member  489  in register with and locked to the female dovetail  493  of the confronting inner and outer housings  491 ,  492 . The locking action is provided by forming a pivot point  508 , as by means of an integral boss, along an arcuate portion at the top of the inner and outer housings  491 ,  492  where they meet when assembled. Note for example, the gaps  509  ( FIG. 83 ) between the confronting edges of the housings at either sides thereof which allow the housings to pivot about point  508  when forced together. Subsequent tightening of the screw  496  forces the bottoms of the housings together as they pivot about the pivot point  508 , to thus clamp the female dovetail  493  about the dovetail member  489  simultaneously with the locking of the shaft means  3  via the shaft grip  495 , the shaft lock  498  and stabilizer locking disks  501 . As may be seen in  FIG. 82A , the slanted inner sides of the dovetail  493  of both housings are provided with reliefs  493 ′, thereby providing three opposing contact areas  493 ″, and three corresponding pressure areas against the circular dovetail member  489  to enhance locking stability. Further, as depicted in  FIG. 82 , solid seating of the dovetail  493  on the dovetail member  489  is insured by forming the bottom, or “horizontal”, seating surface at a slight angle relative to the confronting horizontal surface of the base  473  such that only an outermost portion  507  makes contact along with the matching dovetails. See  FIG. 82B . In addition, shallow reliefs are formed in the portions  507  to provide three separate contact areas thereof which confront the mating seating surfaces on the base  473 , to further eliminate any possibility of a rocking motion due to irregularities in the mating seating surfaces. 
   As previously noted, all similar components in, for example, the  FIGS. 76-88 , are similarly numbered to facilitate the description process and provide continuity in the description of the equivalent components throughout the specification. 
   Referring to  FIGS. 82 and 83 , the outer housing  492  includes a generally semi-spherical outer wall, open at the bottom to include one half of the female dovetail  493 , and inner axially-extending tabs arranged in a cylindrical configuration for facilitating alignment and initial assembly of the housings  491 ,  492 . One pair of diametrically opposite alignment projections  510  ( FIG. 82 ) define a bore  511  therebetween which receives the end of the cylindrical portion  494  of the shaft grip  495 . A second pair of projections comprise hooked clips  512  ( FIG. 83 ) spaced between the projections  510 , which include radially inwardly extending hooks  513  adapted to slide over the end of the cylindrical portion  494  and snap down beyond an annular edge  514  thereof ( FIG. 83 ). This loosely latches the housings  491  and  492  together thereby assembling the shaft-locking support  490  together on the base  473  prior to securing it to the base. An annular lip  489 ′, formed in the periphery of the circular dovetail member  489  (best seen in  FIG. 82 ) and a complementary annular recess in the confronting portions of the housings  491 ,  492 , loosely lock the shaft-locking support  490  to the base  473  to prevent the support  490  from being dislodged from the base while adjustments to the stabilizing means are being made. The outer housing  492  includes a screw bore  515  which rotatably supports the screw  496 . The knob  497  is securely attached to the screw  496  by suitable means such as press fitting, bonding, etc. The opposite end of the screw is provided with external threads adapted to engage internal threads provided in a coaxial bore in the cylindrical portion  494 , as depicted at  516 . 
   The inner housing  491  includes a generally cylindrical outer wall with a radially inwardly extending annular wall  517  formed therein, thereby providing an annular surface  518  facing the shaft means  3 . The stabilizer locking disks  501  of previous mention, which herein include four annular disks, are disposed against the surface  518  and are confined in place by a confronting annular surface of the shaft lock  498 . A pair of alternate disks  501   a  are keyed to the inner housing  491  while the remaining pair of alternate disks  501   b  are keyed to the cylindrical portion  494  of the shaft grip  495 . Thus the locking friction that prevents rotation of the shaft means about the support means  490  axis is increased due to the multiple friction surfaces. The opposite end of the shaft grip  495  includes a passageway  519 , formed by the shaft-enclosing member  488 , within which is disposed the shaft means  3 . The shaft lock  498  is provided with shaft-engaging portions having V-shaped channels  520 ,  FIG. 77  (or  532 ,  FIG. 86 ) which firmly engage the cylindrical surface of the shaft means  3  when the screw  496  is tightened. It follows that the shaft-enclosing member  488  of the shaft grip  495  pulls the shaft means into the shaft lock channels  520  to maximize the friction therebetween. When the screw  496  is not in the locked condition, the spring  499  constantly urges the friction knob  500  against the shaft means  3  to produce sufficient friction to maintain the shaft means in the orientation being set by a surgeon. Once the desired orientation for the shaft means  3  is achieved, the shaft means  3  is locked in place and the shaft-locking support  490  simultaneously is locked to the base  473  by tightening the screw  496  via rotation of the knob  497 . 
     FIGS. 84 ,  85  and  86  depict an alternative embodiment  490   a  of the shaft-locking support  490  of  FIGS. 77 ,  82  and  83 , and particularly of a mechanism thereof which locks the shaft means  3  to the inner and outer housings. Similar components are similarly numbered, while modified but equivalent components are similarly numbered and also include a letter “a”. In the alternative embodiment  490   a , the stabilizer locking disks  501  and the friction knob  500  are dispensed with and in effect replaced by a modified shaft lock  498   a  and a correspondingly modified inner housing  491   a . To this end, the annular end of the inner housing  491   a  terminates in a pair of concentric, annular ridges or teeth  526 , wherein the valleys of the teeth mesh with peaks of corresponding arcuate portions of teeth  528  formed in the confronting surface of the modified shaft lock  498   a . The arcuate length of the teeth  528  in the lock  498   a  may be equal to the width of the lock, as readily seen in  FIG. 86 , or may be formed as an annular disk with annular teeth which mesh with the annular teeth  526  in the housing  491   a . The shaft lock  498   a  includes a depression  529  formed in the center thereof to allow some flexing in annular portions  566  of the shaft lock  498   a . This allows the teeth  528  at the ends of the shaft lock  498   a  to self-align to the valleys of the teeth  526 . When the lock is inserted into the shaft grip  495   a , a compression spring  530  may be inserted within the depression  529 . The spring  530  extends to an annular shoulder  531  formed in the confronting end of a cylindrical portion  494   a  of the shaft grip  495   a . A V-shaped groove  532  is formed in either shaft-engaging portion of the shaft lock  498   a , which grooves face the shaft means  3  within the shaft grip  495   a . At such time as the screw  496  is tightened to lock the stabilizing means, the shaft means  3  is pulled into high frictional contact with the V-shaped grooves  532  of the shaft lock  498   a  by the shaft-enclosing member  488   a  of the shaft grip  495   a . Simultaneously, the teeth  528  of the lock are meshed firmly with the teeth  526  of the inner housing  491   a  regardless of the angular position of the shaft means  3  relative to the generally horizontal second axis (corresponding to the axis of the shaft locking support  490   a ). When the screw  496  is not tight, the spring  530  still applies a small force to the shaft lock  498   a  which applies a small frictional force to maintain the orientation at which the shaft means  3  is set, while still allowing a surgeon to move the shaft means to any other desired orientation. 
   As an alternative to the shaft locks  498  and  498   a  of  FIGS. 82 ,  83  and  84 - 86 , respectively, the annular end of the inner housing  491  or  491   a  may be modified to define a shaft means  3  friction member which, when forced against the shaft means will act as a lock in place of the shaft locks  498  or  498   a . Thus, the shaft locks may be replaced by, for example, a rubber, plastic, etc., annular ring or annular teeth (such as in  FIGS. 84-86 ) against which the shaft means  3  is forced by tightening of the screw means  496  to lock the shaft means  3 . 
   Referring now to  FIGS. 87 and 88 , the handle mechanism  468  of the stabilizing means, illustrated in  FIGS. 76 and 77 , is disclosed in further detail. The mechanism  468  is rotatably secured to the proximal end of the shaft means  3  and is formed at a selected angle to the shaft means to permit a surgeon to swivel the mechanism to a preferred position where the knob  504  is more readily accessible to allow quickly locking the shaft means  3  in the orientation selected. In addition, the angled axis of the knob  504  relative to the shaft means  3  reduces the tendency of the shaft means  3  to rotate about its axis when a surgeon applies torque to the knob  504  to lock the associated locking mechanism. The knob  504  is secured to a screw  539  by suitable means such as press fitting, bonding, etc., whereby the combination knob/screw is similar to the knob  497 /screw  496  of previous mention in  FIGS. 77 ,  82 ,  83 . Right and left handle covers  540 ,  541  comprise the handle  503  and provide the support for the handle mechanism. When assembled, the covers define generally a cylinder formed with the selected curvature. A secondary inner molding, generally indicated at  542 , includes various integrally formed annular walls and shoulders for supporting and containing the knob  504 /screw  539 , as well as a cooperating nut  543 , an arcuate wedge  544 , a shaft retaining ring  545 , the proximal end of the shaft means  3 , and a proximal end of the translatable pushrod  505 . The proximal end of the shaft means  3  includes an annular retaining ring slot  546  which secures the proximal end of the shaft means  3  within suitable annular walls in the corresponding end of the handle covers  540 ,  541  when the retaining ring  545 , confined by shoulders in the inner molding  542 , is snapped into the slot  546  and the covers are assembled. The nut  543  is confined by shoulders in the inner molding  542 , and the arcuate wedge  544  is slidably confined by correspondingly accurate walls  547  also formed in the inner molding. 
   As may be seen, rotation of the threaded screw  539  within the confined threaded nut  543  causes translation of the screw, pivoting and thus translation of the translatable wedge  544  which abuts the screw, and translation of the pushrod  505  which abuts the translatable wedge. As is further described relative to  FIGS. 89-91 , any tightening or loosening of the screw  539 , however slight, will cause a corresponding translation of the pushrod  505  into or out of the shaft means  3 . 
   As depicted particularly in the  FIGS. 76 and 77 , the shaft means  3  and thus the pushrod  505 , are formed with a slight arcuate configuration, which permits additional degrees of freedom of movement and orientation of the distal end of the shaft means  3  and thus of the heart contact member  1 , in accordance with the invention. Rotation of the shaft means  3  about the third axis of previous mention, within the shaft grip  495  or  495   a , moves the distal end of the shaft means  3  through a circular path, while changing the angles through which the contact member  1  can be oriented. This allows a surgeon to conveniently achieve a wider range of positions and orientations of the contact member relative to a patient&#39;s heart, while keeping the proximal end of the shaft means  3  and handle mechanism  468  out of the way as much as possible. 
     FIGS. 89 ,  90  and  91  illustrate an associated mechanism for maneuverably supporting the improved embodiment of the contact member  1  and for cooperatively assisting in the quick locking of the contact member by a partial rotation of the knob  504  once the member is positioned. To this end, the distal end of the shaft means  3  is provided with exterior threads matching interior threads in a ball/socket  548 . The distal end of the ball/socket  548  is provided with slots  549 , whereby the remaining material comprises short extended tips  550  which, when bent in or inwardly formed, form a socket. A ball/post  551  includes a ball at one end and a post at the other. When the mechanism is assembled, the ball/post  551  is inserted into place within the ball/socket  548  with the ball in the socket and the post protruding from the ball socket. A mechanism for providing a preloaded source, such as a compression spring  552 , is coupled to the ball/socket  548  abutting the ball. The spring  552  is urged by the distal end of the shaft means  3  to exert a preloaded or constant minimum force against the ball of the ball/post  551 . The post of the ball/post  551  is solidly fixed as by press fitting, welding, etc., to the contact member  1 . The distal end of the pushrod  505  passes through the spring  552  to abut the ball of the ball/post  551 . Thus when the screw  539  is not tightened, the distal end of the pushrod  505  exerts a slight pressure against the ball, however the spring  552  maintains a preloaded force against the ball sufficient to maintain the contact member  1  at any orientation set by a surgeon. When the screw  539  is tightened, the pushrod  505  is forced against the ball to prevent any further movement of the contact member  1 . As may be seen, the contact member  1  can be tilted to assume many orientations since the narrow center of the post can tilt into any of the four slots in the ball/socket  552 . In addition, simultaneous rotation of the curved shaft means  3  provides a surgeon with even a greater variety of orientations of the contact member relative to a patient&#39;s heart. 
   The contact member  1  includes a preferred configuration which improves the size of the area of the heart which is visible to a surgeon while still providing the required suppression of heart movement necessary to enable the efficient construction of the anastomosis. More particularly, the pair of spaced-apart contact members  1  extend from a common base portion  553 , which uniquely first extends back away from the tips of the contact members at the point of attachment to the post, as shown at reference number  554 . The spaced contact members  1  then curve downward away from the common base portion  553  and back past the post and away from the shaft means  3 . As may he seen in the  FIGS. 76 ,  77 ,  89 - 91 , the contact member  1  of this embodiment uniquely is attached to the post on the same surface as the surface that bears against the surface of the beating heart. Since the members  1  separate at the base portion  553  at a point  555  behind the distal end of the shaft means  3 , a surgeon has an unobstructed and thus optimum view of the heart even below the distal end of the shaft means  3 . As described previously relative to other contact members  1 , the contact members  1  of  FIGS. 89-91  include friction means  556  selectively secured to the bottom surfaces thereof to more securely engage a beating heart. In addition, the tips of the contact members are bent upward in the form of “ski tips” to lessen their impact when the contact members are firmly pressed against a beating heart to suppress the anastomotic site. 
   Although screw means  496 / 497 / 516  and  539 / 504 / 543  are illustrated herein as a locking mechanism for the shaft-locking support  490  and handle mechanism  468 , respectively, it is to be understood that other mechanisms may be employed to fulfill the intent of the invention combination. For example, a cam/lever mechanism may be used to impart translation to a rod whose distal end is selectively coupled to a suitable flange or the like formed with the shaft lock  495  of the shaft-locking support  490 . Such a cam/lever mechanism also may be attached to a rod which in turn imparts a pivoting movement or translation to a suitable bellcrank or pivotable member, which in turn imparts translation to the pushrod  505  of the shaft means  3 . Thus locking mechanisms other than those specifically described herein are intended within the scope of the embodiments of the invention. 
   As mentioned previously, it is the goal of the present invention to provide an apparatus, or collection of apparatus, to facilitate completing a minimally invasive CABG procedure on the beating heart. Thus, each of the devices disclosed herein is preferably provided in an integrated kit, having several individual instruments packaged therein to provide the surgeon with each of the instruments necessary to complete the anastomosis on the beating heart. Since it is intended that the means for stabilizing the beating heart as described herein, win be introduced directly into the thoracic cavity and brought into direct physical contact with the beating heart, it is necessary that each of the devices disclosed herein be subjected to the sterilization techniques suitable for other surgical instruments. It is particularly preferred that a substantial portion of the devices described herein be formed of a biocompatible and sterilizable plastic and maintained in a sterile container completely enclosing the instrument whereby the container provides a barrier against microorganisms and wherein the stabilizer means of the invention and the container in which the instruments are packaged are sterilized. Sterilization of the container and the instruments contained therein may be provided by conventional sterilization methods such as ETO gas, high temperature and pressure, or gamma radiation. Preferably, the container is a sealable flexible bag that may be sterilized either before or after having the instruments of the invention sealed therein. 
   The particular examples set forth herein are instructional and should not be interpreted as limitations on the applications to which those of ordinary skill are able to apply this invention. Modifications and other uses are available to those skilled in the art which are encompassed within the spirit and scope of the following claims.