Abstract:
Apparatus and method for surgery is disclosed which includes a retractor having a substantially planar base defining an opening for overlying an operative site on a patient, and at least one retractor blade slidably mounted to the base. The base is positioned on the patient such that the opening therein overlies the operative site. The operative site is percutaneously accessed, and obstructing tissue is retracted by engaging the tissue with the retractable blade. A surgical instrument is provided which in engageable with the base and operable at the operative site through the opening in the base. A surgical procedure is carried out through the opening in the base with the surgical instrument.

Description:
This application is a divisional of commonly assigned, application Ser. No. 08/801,052 filed Feb. 14, 1997 by Charles R. Sherts et al., now U.S. Pat. No. 5,967,973 which application is a continuation of application Ser. No. 08/717,591 filed Sep. 23, 1996, now abandoned, which application claims priority from Provisional application Ser. No. 60/016,325, filed Apr. 26, 1996. 
    
    
     BACKGROUND 
     1. Technical Field 
     The subject disclosure relates to minimally invasive surgical procedures and apparatus, and more particularly to an instrument and method for performing surgery associated with the thoracic cavity. 
     2. Background of Related Art 
     The diagnosis and treatment of coronary disease and related conditions typically requires access to the heart, blood vessels and associated tissue. Such procedures include cardiopulmonary bypass, valve repair and replacement, and treatment of aneurysms. Access to the patient&#39;s thoracic cavity may be achieved by a large longitudinal incision in the chest. This procedure, referred to as a median sternotomy, requires a saw or other cutting instrument to cut the sternum and allow two opposing halves of the rib cages to be spread apart. U.S. Pat. No. 5,025,779 to Bugge discloses a retractor which is designed to grip opposite sternum halves and spread the thoracic cavity apart. The large opening which is created by this technique enables the surgeon to directly visualize the surgical site and perform procedures on the affected organs. However, such procedures that involve large incisions and substantial displacement of the rib cage are often traumatic to the patient with significant attendant risks. The recovery period may be extended and is often painful. Furthermore, patients for whom coronary surgery is indicated may need to forego such surgery due to the risks involved with gaining access to the heart. 
     U.S. Pat. No. 5,503,617 to Jako discloses a retractor configured to be held by the surgeon for use in vascular or cardiac surgery to retract and hold ribs apart to allow access to the heart or a lung through an operating window. The retractor includes a rigid frame and a translation frame slidably connected to the rigid frame. Lower and upper blades are rotatably mounted to the rigid frame and the translation frame respectively. 
     Once access to the thoracic cavity has been achieved, surgery on the heart may be performed. Such procedures typically require that the heart beat be arrested while maintaining circulation throughout the rest of the body. Cardioplegic fluid, such as potassium chloride (KCl) is delivered to the blood vessels of the heart to paralyze the myocardium. As disclosed in WO 95/15715 to Sterman et al. for example, cardioplegic fluid is infused into the myocardium through the coronary arteries by a catheter inserted into the ascending aorta. Alternatively, cardioplegic fluid is infused through the coronary veins in a retrograde manner by a catheter positioned in the interior jugular vein accessed at the patient&#39;s neck. Such procedures require the introduction of multiple catheters into the blood vessels adjacent the heart, which is a complicated procedure requiring that the desired vessels be properly located and accessed. The progression of the guide wires and catheters must be closely monitored to determine proper placement. Furthermore, the introduction of catheters forms punctures in the blood vessels that must be subsequently closed, and there is an increased risk of trauma to the interior walls of the vessels in which the catheters must pass. 
     Therefore, a need exists for an apparatus and procedure which provides access to the thoracic cavity without causing extensive trauma to the patient. A procedure is needed to at least locally stabilize a predetermined area of the heart surface that is relatively simple to perform and incorporates instruments that are simple and reliable. Furthermore, an apparatus and procedure is needed which provides a stable framework for supporting additional instruments which may be used during these procedures. 
     SUMMARY 
     The present disclosure is directed to instruments for and methods of surgery. A retractor is provided which has a substantially planar base defining an opening for overlying an operative site on a patient, and at least one retractor blade slidably mounted to the base. 
     The base is positioned in the patient such that the opening therein overlies the operative site, and the operative site is percutaneously accessed through the opening. Obstructing tissue is retracted with one or more retractor blades to create an opening to provide access for the surgical procedure. A surgical instrument is provided which is engageable with the base and operable at the operative site. A surgical procedure is carried out through the opening in the base with the surgical instrument. 
     In a preferred embodiment, the retractor blade includes a ratchet assembly, and the method includes fixing the position of the retractor blade with respect to the base with the ratchet assembly. 
     The retractor blade may also include an integral blowing, irrigation or suction assembly operably positioned adjacent the blade to remove blood, fluid, etc. In another embodiment, a light assembly may be incorporated to illuminate designated portions of the surgical field. 
     A heart manipulator is disclosed for use in conjunction with the retractor and is releasably mountable on the base. The heart manipulator assists in atraumatically holding and positioning the heart to facilitate access thereto. In a preferred embodiment the heart manipulator includes a loop shaped frame which supports a mesh cradle. 
     A heart stabilizer instrument is also disclosed. This instrument is preferably configured to be mounted to the base portion and has a heart contacting surface. The heart may be contacted with the heart contacting surface to stabilize the position of a predetermined portion of the heart surface. A heart stabilizer instrument may be provided which is mounted to the base portion and movable with respect thereto. The predetermined portion of the heart surface is substantially stabilized by applying pressure thereto. In a preferred embodiment, the heart stabilizer instrument includes structure configured to compress the coronary artery, and the step of stabilizing a predetermined portion of the heart surface includes applying pressure to the coronary artery with the heart stabilizer instrument. The position of the heart stabilizing device may be locked with respect to the base. 
     The base may be provided to the hospital and/or surgeon in a kit form including one or more retractors. The kit may also advantageously include a heart manipulator and/or heart stabilizing device. 
     The surgical method may further include providing an actuator associated with the retractor blade and configured to effect linear movement of the retractor blade. 
     These and other features of the surgical retractor and method for heart surgery will become more readily apparent to those skilled in the art from the following detailed description of preferred embodiments of the subject disclosure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various embodiments of the subject surgical apparatus are described herein with reference to the drawings wherein: 
     FIG. 1 is a perspective view of a surgical retractor constructed in accordance with a first embodiment of the subject disclosure; 
     FIG. 2 is an enlarged perspective view with parts separated of a retractor blade assembly of the surgical retractor of FIG. 1; 
     FIG. 3 is an enlarged cross-sections view of a portion of the retractor blade assembly, illustrating the mounting of the retractor blade assembly on the base; 
     FIG. 4 is an enlarged cross-sectional view taken along line  4 — 4  of FIG. 1 of the retractor blade assembly mounted to the base; 
     FIG. 5 is an enlarged top view, illustrating the radially inward movement of the retractor blade with respect to the base; 
     FIG. 6 is an enlarged top view, illustrating the ratchet on the retractor blade in engagement with the pawl member associated with the base; 
     FIG. 7 is an enlarged top view, illustrating the pawl member associated with the base moved out of engagement with the retractor blade assembly; 
     FIG. 8 is a perspective view of one embodiment of a heart manipulator mounted to a base; 
     FIG. 9 is a perspective view of a heart manipulator mounted to the base and constructed in accordance with another embodiment; 
     FIG. 10 is an enlarged perspective view of a heart stabilizer instrument mounted to the base; 
     FIG. 11 is a top view in reduced scale of the base portion positioned on the patient&#39;s chest; 
     FIG. 12 is a top view, illustrating retractor blade assemblies mounted to the base portion and retracting the patient&#39;s ribs; 
     FIG. 13 is a top view, illustrating a heart manipulator in position adjacent the patient&#39;s heart; 
     FIG. 14 is an enlarged side view in cross-section, illustrating a heart manipulator mounted to the base and spaced from the heart; 
     FIG. 15 is an enlarged side view in cross-section, illustrating a heart manipulator in contact with the heart; 
     FIG. 16 is a top view, illustrating the heart stabilizer instrument of FIG. 10 mounted to the base; 
     FIG. 17 is a perspective view of the heart stabilizer instrument of FIG. 10 mounted to the base and spaced from the heart; 
     FIG. 18 is a perspective view of the heart stabilizer instrument of FIG. 10 in contact with the heart; 
     FIG. 19 is a perspective view of a surgical retractor assembly and base constructed in accordance with another embodiment of the subject disclosure; 
     FIG. 20 is an enlarged perspective view with parts separated of the retractor blade assembly; 
     FIG. 21 is an enlarged perspective view from below of the retraction knob, illustrating the pinion gearing disposed thereon; 
     FIG. 22 is an enlarged cross-sectional view of the retractor blade assembly mounted to the base; 
     FIG. 23 is an enlarged cross-sectional view of the retractor blade assembly in the process of being mounted to the base; 
     FIG. 24 is an enlarged top view illustrating the radially outward translation of the retractor blade; 
     FIG. 25 is an enlarged top view of the pawl member associated with the base in engagement with the retractor blade; 
     FIG. 26 is an enlarged top view, illustrating the pawl member moved out of engagement with the retractor blade; 
     FIG. 27 is a perspective view of a heart manipulator constructed in accordance with yet another embodiment of the subject disclosure; 
     FIG. 28 is an enlarged cross-sectional view of the mounting assembly for the heart manipulator of FIG. 27; 
     FIG. 29 is a perspective view of a heart stabilizer instrument constructed in accordance with another embodiment of the subject disclosure; 
     FIG. 30 is an enlarged cross-sectional view of the mounting assembly of the heart stabilizer instrument of FIG. 29 in an unlocked position; 
     FIG. 31 is an enlarged cross-sections view of the mounting assembly of the heart stabilizer instrument of FIG. 29 in a locked position; 
     FIG. 32 is a cross-sectional view taken along line  32 — 32  of FIG. 31 illustrating the mounting to the base; 
     FIG. 33 is a top view of the surgical retractor positioned on the patient&#39;s chest, illustrating retractor blade assemblies, a heart manipulator and a heart stabilizer instrument mounted on the base; 
     FIG. 34 is a perspective view of a surgical retractor constructed in accordance with another embodiment of the subject disclosure; 
     FIG. 35 is a perspective view with parts separated of a retractor blade assembly of the surgical retractor of FIG. 34; 
     FIG. 36 is an enlarged side cross-sectional view of the retractor blade assembly, illustrating the positioning adjacent a rib and the mounting of the retractor blade assembly on the base; 
     FIG. 37 is an enlarged side cross-section view of the retractor blade assembly mounted to the base and in the process of retracting a rib; 
     FIG. 38 is a perspective view, illustrating the pawl member and the retractor blade in engagement; 
     FIG. 39 is an enlarged cross-sectional view taken along line  39 — 39  of FIG. 37, illustrating the ratchet on the retractor blade in engagement with the pawl member; 
     FIG. 40 is an enlarged cross-sectional view, illustrating a pawl member associated with the base moved out of engagement with the retractor blade; 
     FIG. 41 is a perspective view of another embodiment of a hear stabilizer instrument mounted to the base of FIG. 34; 
     FIG. 42 is a perspective view with parts separated of the heart stabilizer instrument of FIG. 41; 
     FIG. 42A is a perspective view of the toggle member, illustrating the cable mounting configuration; 
     FIG. 42B is a perspective view from below of the heart stabilizer instrument of FIG. 41; 
     FIG. 43 is a side cross-sections view of the heart stabilizer instrument of FIG. 41; 
     FIG. 44 is a side view in partial cross-section of the heart stabilizer instrument in an unlocked configuration; 
     FIG. 45 is an enlarged cross-sectional view of the toggle mechanism in an unlocked configuration; 
     FIG. 46 is an enlarged cross-sectional view of a portion of the articulating arm, illustrating the cable in a loose configuration corresponding to the unlocked configuration of FIGS. 44-45; 
     FIG. 47 is an enlarged cross-sectional view of the toggle mechanism in an locked configuration; 
     FIG. 48 is a reduced scale side view in partial cross-section of the heart stabilizer instrument in an locked configuration; 
     FIG. 49 is an enlarged cross-sectional view of a portion of the articulating arm, illustrating the cable in a tightened configuration corresponding to the locked configuration of FIGS. 47-48; 
     FIG. 50 is an perspective view of a heart stabilizer instrument mounted to the base in accordance with another embodiment of the present disclosure; 
     FIG. 50A is an enlarged perspective view of the link members of the heart stabilizer instrument of FIG. 50; 
     FIG. 50B is an enlarged perspective view of the link members of the heart stabilizer instrument of FIG. 50; 
     FIG. 51 is a perspective view of a surgical retraction system in accordance with another embodiment of the subject disclosure incorporating a variety of retractors, a heart manipulator and a heart stabilizer, all positioned on a base; 
     FIG. 52 is a top view of the base of FIG. 51 illustrating suture mounts positioned thereabout; 
     FIG. 53 is an enlarged perspective view of the suture mounts of FIG. 52; 
     FIG. 54 is a perspective view of a surgical retractor in accordance with the subject disclosure incorporating an integral blowing structure; 
     FIG. 55 is a reverse perspective view of the surgical retractor of FIG. 54; 
     FIG. 56 is an enlarged perspective view with parts separated of the surgical retractor of FIG. 54; 
     FIG. 57 is a perspective view of a surgical retractor in accordance with the subject disclosure incorporating a light; 
     FIG. 58 is a reverse perspective view of the surgical retractor of FIG. 57; 
     FIG. 58A is a top plan view in partial cross-section of a surgical retractor mounted to the bases of FIG. 52; 
     FIG. 58B is a top plan view in partial cross-section of the surgical retractor in FIG. 58A pulled proximally relative to the base; 
     FIG. 58C is a top plan view in partial cross-section of the surgical retractor in FIG. 58A released from engagement with the rack; 
     FIG. 59 is a perspective view of another embodiment of a heart stabilizer instrument of FIG. 59, illustrating a positioning flange formed thereon; 
     FIG. 60 is an enlarged perspective view of a portion of the heart stabilizer instrument of FIG. 59, illustrating a positioning flange formed thereon; 
     FIG. 61 is a perspective view with parts separated of the heart stabilizer instrument of FIG. 59; 
     FIG. 62 is a perspective view of the mounting flange member of the heart stabilizer instrument of FIG. 59; 
     FIG. 63 is a perspective view of the movable handle of the heart stabilizer instrument of FIG. 59; 
     FIG. 64 is a top plan view in partial cross-section of the heart stabilizer instrument of FIG. 59 with the movable handle in the unlocked unstressed position; 
     FIG. 65 is a cross-sectional view taken along line  65 - 65  of FIG. 64, illustrating the relative position of the handle spring member; 
     FIG. 66 is a top plan view in partial cross-section of the heart stabilizer instrument of FIG. 59 with the movable handle in the locked unstressed position; 
     FIG. 67 is a cross-sectional view taken along line  67 — 67  of FIG. 66, illustrating the relative position of the handle spring member; 
     FIG. 68 is a top plan view in partial cross-section of the heart stabilizer instrument of FIG. 59 with the movable handle in the locked and stressed position; 
     FIG. 69 is a cross-sectional view taken along line  69 — 69  of FIG. 68, illustrating the relative position of the handle spring member; 
     FIG. 70 is a perspective view of another embodiment of a heart manipulator; 
     FIGS. 71A and 71B are front and back perspective views of the rib elevator; 
     FIG. 72 is a perspective view of a kit assembly having a base, three retractors, a retractor knob, a heart manipulator and a heart stabilizer instrument; and 
     FIG. 73 is a perspective view of a kit assembly having a base, a retraction knob and three retractors. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The preferred embodiments of the apparatus disclosed herein will be discussed in terms of procedures and apparatus for heart surgery. However, the subject disclosure should not be limited to an apparatus for use in conjunction with such heart surgery, but may find application in surgery wherein access to the surgical site is achieved through a small incision and retraction of the surrounding tissues and/or bone is desired. 
     Referring now in detail to the drawings in which like reference numbers identify similar or identical elements, a first embodiment of the surgical retractor of the subject disclosure is illustrated in FIG. 1, and is designated generally by reference numeral  10 . Surgical retractor  10  has base  12  and retractor blade assembly  14 , including mounting assembly  16  and retractor blade  18 . As will be described below, base  12  in this embodiment is configured to be placed on the chest of a patient surrounding an incision. Retractor blade  18  includes hook  20  configured for atraumatically engaging a rib. Strap  22  assists the surgeon in drawing the retractor blade  18  radially outward and retracting a rib therewith. One-way ratchet assembly  23  on mounting assembly  16  retains retractor blade  18  in position. Base  12  is also configured to receive surgical instruments for mounting thereon, as will be described below. 
     Base  12  preferably has a closed shape, such as an oval configuration as shown, or a circle, polygon, or the like. Base  12  is sized suficiently large in order to enclose sufficient area to provide access to the operative site. The bottom portion of base  12  is preferably configured to permit placement directly on the skin of the patient with the base substantially flush with the patient&#39;s skin. Suture mounts  24   a,    24   b,    24   c  may be provided at several locations on the base  12  to permit suture tie down of internal tissue structures such as the pericardial sac. Outer periphery  26  of base  12  includes a series of outwardly extending teeth  27  formed thereon to provide additional stability to the positioning of mounting assembly  16  and other instruments on base  12 . Base  12  also includes a beveled inner surface  28  with an inner lip  30 , and top surface  32 . Base  12  has a low profile when placed on the body. Base  12  is rigidly supported by pressure from retractor blade assembly  14  on the ribs in three or four locations. Preferably, three retractor blade assemblies are disposed on base  12  at 120° apart. Retractor blade assemblies may be disposed 90° apart. 
     Turning now to FIG. 2, mounting assembly  16  permits quick and stable mounting of the retractor blade assembly to base  12 . Mounting assembly  16  includes mounting bracket  34 , retainer block  36 , and retainer spring  38 . Gripping flange  40  on mounting bracket  34  is configured to engage inner lip  30  of base  12  (FIGS.  3  and  4 ). Sleeve  42  forms an open-sided channel  44  for sliding reception of retractor blade  18 . Pawl member  46  is formed on mounting bracket  34  and has a series of engaging teeth  48  which communicate with the open side of channel  44  for engaging retractor blade  18 , as will be described below. Mounting bracket  34  defines a cavity  49  for mounting retainer block  36  therein. Cavity  49  is partially defined by outer retainer wall  50  with upper flange  51  and by inner wall  52  having aperture  53 . Retainer block  36  is radially slidable within cavity  49  and is biased inward by retainer spring  38  such that engagement teeth  54  on retainer block  36  protrude through aperture  53 , to engage teeth  27  provided on periphery  26  of base  12 . Retainer block  36  also includes handle  56  which permits the surgeon to move retainer block  36  towards retainer wall  50  against the bias of retainer spring  38 , in order to disengage teeth  54  from base  12 . 
     Retractor blade  18  includes curved hook  20  on a distal end portion and slot  57  on a proximal end portion to receive flexible assist strap  22  therethrough. A series of ratchet teeth  58  are provided on an edge of retractor blade  18  and engage teeth  48  of pawl member  46  when retractor blade  18  is disposed in channel  44  of mounting bracket  34 . 
     As illustrated in FIGS. 3-4, mounting assembly  16  is mounted to base  12  in a simple, one-handed operation. FIG. 3 illustrates retainer block  36  displaced towards retainer wall  50  against the normal bias of retainer spring  38 . Handle  56  of retainer block  36  facilitates approximation of retainer wall  50  with flange  51  of retainer wall  50 . Mounting assembly  16  is lowered onto base  12  at an angle as shown such that gripping flange  40  engages inner lip  30  of base  12 . Engagement teeth  54  are angled to permit camming over outer lip  60 . FIG. 4 illustrates mounting assembly  16  into position with respect to base  12 , upon which retainer block  36  is released, which thereby returns inward towards base  12  under the normal bias of spring  38 . Engagement teeth  54  pass under outer lip  60  and engage teeth  27  on periphery  26  of base  12 . 
     Turning to FIGS. 5-7, the progression of retractor blade  18  with respect to mounting bracket  34  is illustrated. Ratchet assembly  23  includes pawl  46  on mounting bracket  34  and teeth  58  on retractor blade  18 . Pawl  46  is normally biased towards retractor blade  18 . Pawl teeth  48  and retractor blade teeth  58  are each configured with a sloping portion and a straight portion. This permits retractor blade  18  to be progressively displaced in a radially outward direction as indicated by arrow “O” in FIG.  5 . As illustrated in FIG. 6, radially inward displacement of retractor blade  18  is prevented by engagement of pawl teeth  48  and retractor blade teeth  58  under the normal bias of pawl  46 . The arrangement of teeth, as shown in FIGS. 5-6 permits retraction of a rib or other body structure and prevents slipping of or loss of retraction force exerted by retractor  18 . As illustrated in FIG. 7, retractor blade  18  is permitted to displace radially inward as indicated by arrow “I” when pawl tab  62  is rotated clockwise causing it to move away from retractor blade  18  against its normal bias by actuation of tab  62 . Unrestricted movement of retractor blade  18  is permitted in both radially inward and radially outward directions when tab  62  is moved to the position of FIG.  7 . 
     FIG. 8 illustrates a heart manipulator  64  for use in conjunction with surgical retractor  10  and for mounting on base  12 . Heart manipulator  64  includes loop shaped frame  66  that supports mesh surface  68 . Frame  66  and mesh surface  68  together form a heart contacting surface for manipulating the heart therewith. Preferably, frame  66  includes upright portion  70 , generally horizontally extending portion  72  and atraumatic curved end portion  74 , which provide a surface for engaging and manipulating the heart. Frame  66  is supported by mounting bar  76  which is slidably received in support bracket  78  for height adjustment. Set screw  80  secures mounting bar  76  with respect to support bracket  78 . Radial positioning of support bracket  78  and heart manipulator  64  is achieved by slidable mounting of support bracket  78  on mounting assembly  82  which mounts to base  12  in a manner substantially similar to that of mounting assembly  16  described above with respect to FIGS. 3-4. Set screw  84  secures the radial position of heart manipulator  64  with respect to mounting assembly  82 . More particularly, support bracket  78  has an elongated slot  79  formed therein which enables bracket  78  to slide radially with respect to set screw  84  and mounting assembly  82 . As shown in FIG. 14, mounting assembly  82 , like mounting assembly  16 , has a mounting bracket  83  which engages inner lip  30  of base  12 , retainer block  81 , and retainer spring  87 . Handle  89  of retainer block  81  enables the engagement and disengagement of mounting assembly  82  in the same manner as mounting assembly  16  described above. 
     Turning to FIG. 9, a heart manipulator  90  is shown in accordance with another preferred embodiment. Loop frame  66  and mounting assembly  82  are substantially as described above with respect to heart manipulator  64  in FIG.  8 . Mounting bar  92  supports frame  66  and has substantially right angled bend  94  for slidable insertion in support bracket  96 . Radial position of heart manipulator  90  is achieved by sliding mounting bar  92  with respect to support bracket  96  and secured thereto by set screw  98 . Although height adjustment of heart manipulator  90  is not provided, access to the operative site is enhanced by the one-piece design of mounting bar  92 . 
     FIG. 10 illustrates a heart stabilizer instrument  100 , configured to apply pressure to the coronary artery to reduce blood flow in the artery to allow anastomosis to the coronary artery and to reduce movement of the heart muscle between legs  104   a,    104   b  in order to enable the surgeon to perform cardiovascular surgery. Heart stabilizer instrument  100  is mounted to base  12  by mounting assembly  82 , substantially as described above. Heart stabilizer instrument  100  includes frame  102  supporting legs  104   a  and  104   b  and transverse bars  106   a  and  106   b.  Protrusion  108   a  is formed on transverse bar  106   a,  and protrusion  108   b  is formed on transverse bar  106   b.  Protrusions  108   a  and  108   b  have an atraumatic convex heart contacting surface and permit the exertion of localized pressure on the coronary artery when frame  102  is compressed on the surface of the heart. Mounting bar  110  is slidably received in support bracket  78  and secured with respect thereto by set screw  80 . Radial positioning of heart stabilizer instrument  100  with respect to mounting assembly  82  is secured by a coupling means, such as set screw  84 . 
     Turning now to FIG. 11, the operation of the surgical retractor  10  will now be described. Conventional surgical techniques are used to determine the location of the incision I accessing the chest cavity C. Base  12  is placed on the chest of the patient with the opening overlying the operative site. Incision I is made, exposing several ribs R 1 , R 2 , and R 3 . 
     As illustrated in FIG. 12, retractor assemblies  14   a,    14   b,  and  14   c  are mounted to base  12  at various location. Hook  20   a  is positioned around a rib R 1 . Assist strap  22   a  is used to provide a grip for the surgeon to deflect and retract rib R 1  by pulling retractor blade  18  radially outward. One way ratchet assembly  23   a  maintains retractor blade  18  and consequently rib R 1  in position. Rib R 2  is retracted in a substantially identical manner by hook  20   b  on retractor assembly  14   b.  Additional retractors are mounted and used to retract ribs until a sufficiently large opening O in chest cavity C is defined in order to provide access to the heart. Although three retractors are shown, it is contemplated that a fewer number or a greater number of retractors could be utilized, and these retractors can be mounted anywhere along base  12  in order to perform their function. For example, the sternum and the fourth and fifth ribs can be spread apart to create a window. Alternatively, the fourth and fifth ribs are cut from the sternum and spread to create a larger window. Alternatively, a fifth rib can be cut, and the sternum and the fourth and sixth ribs are spread. 
     Base  12  is at least partially held in position over the operative site by tension created in retracting the ribs by retractor blades  18 . Internal tissue structures may be tied down utilizing sutures passing through securement points  24   a,    24   b,    24   c  and  24   d.    
     Turning now to FIG. 13, heart manipulator  64  is mounted to base  12  in order to manipulate the position of heart H to facilitate the surgery. With reference to FIG. 14, heart manipulator  64  is positioned in the chest cavity adjacent heart H. Frame  66  and mounting bar  76  can be lowered and fixed by a set screw  80  such that horizontal portion  72  and curved end portion  74  are positioned slightly underneath heart H. As illustrated in FIG. 15, heart manipulator  64  is displaced radially inward and against heart H by loosening set screw  84  and sliding mounting bar  92  in the direction of the arrow. When sufficient pressure is placed on the heart to substantially fix its position, heart manipulator  64  is secured by the tightening of set screw  84 . 
     With the heart manipulated to the desired position, FIG. 16 illustrates the mounting of heart stabilizer instrument  100  to base  12 . As illustrated in FIG. 17, heart stabilizer instrument  100  is positioned over heart H and more particularly, over coronary artery A. The radial positioning of instrument  100  is accomplished by relative movement of support bracket  78  with respect to mounting assembly  82 . 
     As illustrated in FIG. 18, frame  102  and mounting bar  110  are lowered with respect to support bracket  78  such that frame  102  applies direct pressure on heart H. Protrusions  108   a  and  108   b  localize this pressure to substantially restrict the flow of blood from coronary artery A and  104   a  and  104   b  reduce movement of the surface of the heart muscle to facilitate the surgery. Heart movement is restricted by virtue of the leg pressure and the anti-slip texture of the legs  104   a  and  104   b.  The position of instrument  100  may be locked with respect to the base as set forth in detail below. 
     Turning now to FIGS. 19-33, another preferred embodiment of the surgical retractor is disclosed at reference numeral  200 . Instrument  200  operates substantially as described above with regard to instrument  10 , with the differences described hereinbelow. In particular, FIG. 19 illustrates surgical retractor  200  having base  212  and retractor blade assembly  214 , which includes mounting bracket  216 , retractor blade  218  and retraction knob  220 . The provision of retraction knob  220  enables the surgeon to achieve additional mechanical advantage in retracting a rib. 
     Base  212  includes suture mounting portions  224   a,    224   b,    224   c  and  224   d  for securing base  212  adjacent the surgical site. Base  212  further includes beveled inner surface  228  with inner lip  230  and top surface  232  in which a series of cylindrical recesses or openings  240  are defined. 
     As illustrated in FIG. 20, mounting bracket  216  includes sleeve  242  defining open-sided channel  244  for sliding reception of retractor blade  218 . Pawl member  246  has a series of ratchet teeth  248  configured to engage ratchet teeth  258  on retractor blade  218  when blade  218  is slidably inserted in channel  244 . 
     Retraction knob  220  is rotatably positioned in aperture  236  in mounting bracket  216 . With reference to FIG. 20 in conjunction with FIG. 21, retraction knob  220  includes pinion gear  260  which cooperates with rack  262  provided on retractor blade  218 . As will be described below, rotation of knob  220  provides additional mechanical advantage in cooperation with one-way ratchet mechanism  23  to retract and/or advance retractor blade  218 . 
     As illustrated in FIGS. 22-23, retractor blade assembly  214  is mounted to base  212  in a simple, one-handed motion. Mounting bracket  216  includes pin  264  on a bottom portion thereof dimensioned to be received in one of cylindrical recesses  240  in base portion  212 . The length of pin  264  is preferably substantially equivalent to the depth of recess  240  to provide stability to mounting bracket  216 . In addition, wedge shaped inner portion  266  of mounting bracket  216  cooperates with beveled inner surface  228  of base  212  to facilitate positioning and to provide resistance against tilting of retractor blade  218 . Mounting bracket  216  is further secured in position by tab  270  which includes a flange  272  which engages outer rim  274  of base  212 . As illustrated in FIG. 23, removal and placement of mounting bracket  216  is accomplished by deflecting flange  272  of tab  270  clear of outer rim  274 . Tab  220  includes rigid lever arm  276  which facilitates such deflection of tab  270 . 
     Turning to FIGS. 24-26, the interaction of retractor blade  218  with respect to mounting bracket  216  is illustrated. Ratchet assembly  223 , which includes pawl  246  and sloping teeth  258  function substantially as described above with respect to FIG. 5, and permits retractor blade  218  to be progressively displaced radially outwardly while preventing radially inward displacement. Initially, assist straps  22  (See, FIG. 19) are used by the surgeon to retract a rib. Retracting blade  218  is displaced radially outwardly as far as possible given the strength of the surgeon. Subsequently, additional retraction force can be applied to the rib by rotation of retraction knob  220 . Pinion gear  260  disposed on knob  220  engages rack  262  on retraction blade  218  and provides additional leverage to the surgeon. As illustrated in FIG. 25, pawl  246  is normally biased against retraction blade  218  such that ratchet teeth  258  on blade  218  and ratchet steel  248  on pawl  246  engage to prevent radially inward movement. It should be appreciated that knob  220  is optionally removable so it can be used to retract each retractor blade  218 . 
     FIG. 26 illustrates that pawl  246  may be rotated away from retraction blade  218  by pivoting lever  262  to disengage teeth  258  and  248 . Unrestricted radial movement of retraction blade  218  is facilitated thereby. 
     FIGS. 27-28 illustrated another embodiment of a heart manipulator instrument designated by reference number  300 . Heart manipulator  300  is used to manipulate the position of the heart and operates substantially as described above with regard to heart manipulator  64 , with the differences described below. In particular, hear manipulator  300  includes frame member  302 , formed in a modified “U” configuration having an upright portion wherein the bars are parallel, including closely spaced mounting portions  304   a  and  304   b,  more widely spaced mesh supporting portions  306   a  and  306   b,  and a curved horizontally extending portion  308 . Mesh supporting portions  306   a  and  306   b  and horizontally extending portion  308  support a mesh surface  310  therebetween. Mounting portions  304   a  and  304   b  are snap fit within bores formed in support bracket  320 . It is contemplated that members  304   a  and  304   b  may be slidable with respect to bracket  320  and secured with set screws (not shown). Radial positioning of support bracket  320  is achieved by slidable mounting of support bracket  320  on mounting bracket  322 . Set screw  324  is used to secure the radial positioning of heart manipulator  300 . Elongated slot  330  allows movement of support bracket  320  with respect to set screw  324  and mounting bracket  322 . 
     Turning now to FIG. 28, mounting bracket  322  is configured to mount on base  212  substantially as described with respect to mounting bracket  216  in FIGS. 22-23. Pin  364  of bracket  322  is received in one of openings  240  in base  212 . Tab  370  includes flange  372  which removably engages outer rim  274  of base  212  and is disengaged by lever arm  376 . Support bracket  320  is slidably mounted on mounting bracket  322  such that a portion of slot  330  is aligned over threaded bore  332 . Set screw  324  extends through slot  330  into bore  332  and includes collar  334  which abuts a top surface of support bracket  320  to secure it against radial movement. 
     FIGS. 29-32 illustrate a heart stabilizer instrument  350  in accordance with another preferred embodiment of the subject disclosure. With reference to FIG. 29, heart stabilizer instrument  350  includes frame  102  and mounting bar  110 . Frame  102  includes legs  104   a  and  104   b  and transverse bars  106   a  and  106   b  having protrusions  108   a  and  108   b  substantially as described with respect to FIG. 10, above. Mounting bar  110  is slidably received in a bore in support bracket  352  and secured with respect thereto by set screw  354 . Support bracket  352  is slidable with respect to mounting bracket  356 . 
     As illustrated in FIGS. 30-31, mounting bracket  356  is removably mounted on base portion  212  substantially as described with respect to mounting bracket  216  in FIGS. 22-23. Pin  358  is received in one of cylindrical recesses or openings  240  in base  212 . Tab  360  includes flange  362  for removably engaging outer rim  274  of bore  212 . Flange  362  is disengaged by actuation of lever arm  364 . With reference to FIG. 32 in conjunction with FIGS. 30-31, support bracket  352  includes a pair of vertical walls  364   a  and  364   b  and a pair of horizontal walls  366   a  and  366   b  which rest on a top surface of mounting bracket  356 . A lever mounting rod  368  extends upwardly from mounting bracket  356  between horizontal walls  366   a  and  366   b.  A pair of hinge pins  370   a  and  370   b  extend from rod  368  and are received in a clevis portion  372  of lever arm  374 . Horizontal walls  366   a,    366   b  of support bracket  352  are disposed between mounting bracket  356  and clevis portion  372  of lever arm  374 . 
     With continued reference to FIGS. 30-31, clevis portion  372  is substantially circular or elliptical in lateral cross-section and is eccentrically mounted to hinge pins  370   a  and  370   b.  As illustrated in FIG. 30, when lever arm  374  is in a released position, clevis portion  372  is spaced from horizontal walls  366   a  and  366   b  and unrestricted radial movement of support bracket  352  is enabled thereby. As illustrated in FIG. 31, pivoting of lever arm  374  causes clevis portion  372  to apply a compressive force on horizontal walls  366   a  and  366   b  on top of mounting bracket  356  to thereby fix the radial position of support bracket  352  with respect to mounting bracket  356 . 
     Turning to FIG. 33, operation of surgical retractor  200  in conjunction with heart manipulator and heart stabilizer instrument proceeds substantially as described with respect to FIGS. 11-18. As noted above, mounting bracket  216   a  of retractor blade assembly  214  is placed on base  212  by actuation of lever arm  276   a  (not shown). Heart manipulator  200  and heart stabilizer instrument  350  are mounted to base  212  in a substantially identical manner as described above. The surgical procedure is carried out substantially as described above. Ribs R 1 , R 2  and R 3  are retracted by the pulling of assist straps  22  and by the rotation of retraction knob  220 . The position of heart H is stabilized by heart manipulator  300 . Heart stabilizer instrument  350  is positioned and lowered onto heart H to apply pressure to the coronary artery and thereby substantially reduce movement (motion) of the heart within the legs. The instrument  350  may be locked with respect to the base. At this time, other surgical procedures, such as coronary bypass or valve surgery may be performed. 
     Turning now to FIGS. 34-52, another embodiment of the surgical retractor is disclosed at reference number  400 . Instrument  400  operates substantially as described with regard to instrument  200 , with the differences noted hereinbelow. In particular, FIG. 34 illustrates surgical retractor  400  having base  412  and retractor blade assembly  414 , which includes mounting bracket  416 , retractor blade  418 , and retraction knob  420 . The provision of retraction knob  420  enables the surgeon to achieve additional mechanical advantage in retracting a rib. 
     Base  412  includes suture mounting portions  424  for suture tie down of internal tissue structures. Base  412  further includes beveled inner surface  428  with inner lip or rim  430  and top surface  432 , which forms an outer lip or rim  434 . A channel or groove  436  is formed in top surface  432 . Outer periphery  438  of base  412  includes a series of teeth  440  formed thereon. 
     As illustrated in FIG. 35, mounting bracket  416  includes housing  442  and mounting plate  444  which are connected and allow retractor blade  418  to slide within channel  446  defined in a lower surface of housing  442 . 
     Retractor blade  418  includes body portion  448  and rib engaging portion  450 . Body portion  448  defines a T handle  452  configured to be grasped by the surgeon in order to slide retractor blade  418  within channel  446 . Body portion  448  defines a rack gearing  454  and a series of sloping ratchet teeth  456 . Preferably, such gearing  454  and ratchet teeth  456  are respectively disposed along elongated channel  458  defined within body portion  448 . 
     Ratchet teeth  456  are releasably engaged by pawl  460 . Mounting plate  444  defines first channel  462  and second channel  464  for receiving pawl  460 . Preferably, pawl  460  is a resilient member having a modified U-shaped configuration including crown portion  466 , first leg  468  defining cut-out portion  470 , and second leg  472 . Second leg  472  is fixedly retained within second channel  464  having an elbow configuration. The junction of second leg  472  and crown  466  acts as a hinge or pivot such that first leg  468  is slidable within first channel  462 . Pawl  460  is normally biased at this junction of second leg  472  and crown  466  such that first leg  468  is partially disposed in first channel  462 . Crown  466  may be pressed by the user towards mounting plate  444  against the normal bias to slide first leg  468  further along first channel  462 . Retractor blade  418  is positioned adjacent mounting plate  444 , and pawl  460  is placed on top of blade  418  such that cut-out portion  470  of first leg  468  straddles a portion of blade  418  adjacent ratchet teeth  456 . (See, FIG. 38) As will be described below, pawl  460  is normally biased such that first leg  468  is in engagement with one of ratchet teeth  456 . Pawl  460  and ratchet teeth  456  together define a one-way ratchet mechanism  474 . 
     Rack gearing  454  is engaged by pinion gearing  476  formed on retraction knob  420 , which is position in aperture  478  defined in housing  442 . As will be described below, rotation of retraction knob  420  provides additional mechanical advantage when used in cooperation with ratchet mechanism  474  to retract and/or advance retractor blade  418 . 
     Rib engaging portion  450  is connected to body portion  448  with a dovetail joint and secured thereto with pins  480   a  and  480   b.  Alternatively, retractor blade  418  may be constructed of a single part. Rib engaging portion  450  includes a horizontal portion  482 , angularly depending portion  484 , and tip portion  486 . Angularly depending portion  484  forms an acute angle with horizontal portion  482  to securely engage the rib. Strengthening rib or beading  448  is formed on the outside of rib engaging portion  450  to provide additional strength and to resist bending. 
     Referring to FIG. 35 in conjunction with FIGS. 36-37, mounting plate  444  includes a gearing  490  on a forward portion thereof to engage peripheral gear teeth  440  on base  412  (See, FIG.  34 ). 
     As illustrated in FIG. 36, base  412  is placed at the operative site on patient&#39;s chest. Rib engaging portion  450  is positioned adjacent rib R, such that angularly depending portion  484  and tip portion  486  at least partially surround rib R. Housing  442  has a flat bottom portion and is placed on upper surface  432  of base  412 . 
     FIG. 37 illustrates the simultaneous mounting of mounting bracket  416  to base  412  and retraction of rib R towards base  412  as indicated by the arrows. Retractor blade  418  is moved radially outward with respect to base  412  while rib engaging portion  450  engages rib R. Mounting plate  444  is spaced from the bottom portion of housing  442  in order to permit mounting plate  444  to slide under outer rim  434  of base  412 , and to allow teeth  490  engage teeth  440  on base  412 . Mounting bracket  416  is secured on base  412  by the compression force created between rib engaging portion  450  against rib R and mounting plate  444  against outer rim  434  of base  412 . Removal of retractor blade  418  from rib R occurs by sliding retractor blade  418  radially inward, thereby releasing compression sufficiently to allow mounting plate  444  to be released from outer rim  434 . 
     One-way ratchet mechanism  474  enables retractor blade  418  to be incrementally moved in one direction, i.e. radially outwardly to retract a rib, while resisting movement in an opposite direction, i.e. radially inward. FIG. 38 illustrates pawl  460  normally biased such that first leg  456  is in engagement with ratchet teeth  456 . As shown in FIG. 39, sloping portions  490  of teeth  456  permit retractor blade  418  to incrementally move in a radially outward motion while transverse slopes  492  of teeth  456  inhibit radially inward motion to hold retractor blade  418  and the rib in position. AS described above with respect to retractor  200 , additional retraction force can be applied to the rib by rotation of retraction knob  420 . Pinion gear  476  disposed on retraction knob  420  engages rack  454  on retraction blade  418  to provide additional leverage to the surgeon. After retracting the rib to create sufficient access for the surgeon, rotation knob  420  may be removed from aperture  478  in housing  442  (See, FIG. 35) and thereby provide greater visibility and access for the surgeon. 
     Pawl  460  may be moved against its normal bias by depressing crown  466  towards mounting plate  444 , which causes first leg  468  to disengage from ratchet teeth  456  as shown in FIG.  40 . Cut-out portion  470  as aligned such that blade  418  may slide therethrough, such that unrestricted radial movement of retraction blade  418  is enabled. 
     FIGS. 41-49 illustrate a heart stabilizer instrument  500  in accordance with another preferred embodiment of the subject disclosure. With reference to FIG. 41, heart stabilizer instrument  500  includes frame  502 , articulating arm  504 , and mounting assembly  506 . Articulating arm  504  is configured to allow frame  502  to be positioned at the precise location and orientation with respect to the heart of the patient. Mounting assembly  506  secures articulating arm  504  and frame  502  in a fixed configuration, as will be described below. 
     Frame  502  is configured to contact the heart and applies pressure to the heart without touching the coronary artery. Frame  502  includes a pair of legs  508   a  and  508   b,  each having teeth  510  for atraumatically contacting the heart. Frame  502  is mounted to frame mount  512  by pin  514 . The distal end of cable  516  is mounted to frame  502 , and passes into frame mount  512  at opening  513 . 
     Articulation arm  504  consists of a plurality of link members  518   a,    518   b,    518   c,    518   d,  each of which has hemispherical convex distal portion  520 , cylindrical body portion  522  including peripheral step  523 , and concave proximal end  524 . Bore  526  extends longitudinally through each link  518  from convex distal portion  520  to concave proximal end  524 . Link members  518  are aligned such that convex distal portion  520  is received in concave proximal end  524  in a ball-and-socket type connection to permit a wide range of pivoting motion between adjoining link members  518 . Link members  518  are concatenated by cable  516  passing through each bore  526 , and the distalmost link member  518   a  is fitted adjacent frame mount  512 . Articulation arm  504  can be used to mount a light cable to illuminate the surgical site, a suction and/or irrigation device, a blowing device to disperse blood or any other instrument to facilitate the surgery. 
     Mounting assembly  506  is mounted adjacent proximalmost link member  518   d  and includes mounting flange member  530 , mounting base  532 , toggle housing  534 , and toggle  536 . As shown in FIG. 42B, mounting base  532  has a flat bottom surface  538  to rest on top surface  432  of base  412  and a protrusion or peg  540  configured and dimensioned to be received in flange  436  of base  412 . With continued reference to FIG. 42, mounting flange member  530  and toggle housing  534  are slidably mounted with respect to mounting base  532  by springs  542  and  544 , respectively. Mounting flange member  530  has flange  546  for engaging inner rim  430  of base  412 . Toggle housing  534  has flange  548  for engaging outer rim  434  of base  412 . 
     Toggle  536  includes cylindrical mounting portion  550  and toggle arm  552 . Cylindrical mounting portion  550  is configured to be received within cylindrical recess  554  defined within toggle housing  534  and to be pivotably movable therein. Cable  516  extends through link members  518  and through mounting flange member  530 , spring  542 , mounting base  532 , spring  544 , and into cylindrical recess  554  of toggle housing  534 . The distal end portion of cable  516  is pinned to toggle  536  by pin  556 . As illustrated in FIG. 42A, cylindrical mounting portion  550  defines a laterally offset pie-shaped or arc-section recess  558  to define an “over-center” type locking mechanism, as will be described below. 
     As illustrated in FIG. 43, heart stabilizer instrument  500  is configured such that cable  516  extends through instrument  500  from frame  502  to toggle  536 . Bore  526  in each link member  518  has a tapering diameter which is larger adjacent convex distal portion  520  and is narrower adjacent concave proximal portion  524 . This configuration permits relative articulation of link members  518  while cable  516  extends therethrough. 
     FIGS. 44-46, illustrate heart stabilizer instrument  500  with cable  516  in a relaxed unstressed configuration. As illustrated in FIG. 44, instrument  500  is placed on base  412  such that peg  540  is disposed in groove  436 , and mounting flange member  530  and toggle housing  534  are spaced apart sufficiently to allow flanges  546  and  548  to clear inner rim  430  and outer rim  434 , respectively. 
     As illustrated in FIG. 45, toggle  536  is disposed in toggle housing  534  in an unlocked configuration, such that toggle arm  552  and fixed arm  535  are spaced apart. Eccentrically mounted pin  556  is disposed such that cable  516  is loose. FIG. 46 illustrates that cable  516  loosely disposed in tapered bores  526  of link member  518  permit articulation of adjoining link members  518 . 
     FIGS. 47-49 illustrate instrument  500  with cable  516  in a taut, stressed configuration. As depicted in FIG. 47, toggle  536  is pivoted with respect to toggle housing  534  such that toggle arm  552  is approximated with fixed arm  535 . Simultaneously, the distal end of cable  516  connected to pin  556  moved into an “over-center” position, thereby stressing cable  516  and locking surgical instrument  500  in position. The surgeon is permitted to perform other procedures without maintaining pressure on the heart. 
     Another embodiment of the heart stabilizer instrument is illustrated in FIG.  50  and disclosed at reference number  600 . Instrument  600  is constructed and operates substantially as described above with regard to instrument  500 , with the differences described below. Heart stabilizer instrument  600  includes frame  502 , articulating arm  606  and mounting assembly  506 . Articulating arm  606  permits frame  502  to be placed at the appropriate height and angle with respect to the heart. Articulating arm  606  is composed of link members  608 , and  610  having a series of intermeshing teething to positively engage adjoining link members together. 
     As illustrated in FIGS. 50A and 50B, link members  608  are positioned adjacent link member  610 . Link member  608  has generally cylindrical body portion  612 . A pair of rows of concave gearing  614   a  and  614   b  is disposed on one axial end  616  of link member  608 . A second pair of rows of concave gearing  618   a  and  618   b  is disposed on the second axial end  620  of link member  608 . Gearing  614   a  and  614   b  is disposed 90° out of alignment with gearing  616   a  and  616   b.  Longitudinal bore  622  extends through link member  608  from axial end  616  to axial end  620  between each pair of gearing. 
     Link member  610  has body portion  624 , to which first pair of gearing  626   a  and  626   b  having a convex profile and second pair of convex gearing  628   a  and  628   b  are attached to opposite sides thereof. First pair of gearing  626   a  and  626   b  is disposed 90° out of alignment with second pair of gearing  628   a  and  628   b.  A longitudinal bore (not shown) extends through body portion  624  and between each pair of gearing  626   a  and  626   b  and gearing  628   a  and  628   b.    
     Link member  610  is placed adjacent link member  608 . Cable  516  extends through longitudinal bore  622  in link member  608  and longitudinal bore (not shown) in link member  610 . When toggle  552  is moved to the “over center” position (See, FIG.  47 ), thereby tightening cable  516 , link members  608  and  610  are approximated such that convex gearing  626   a,    626   b  or  628   a,    628   b  of link member  610  engages concave gearing  614   a,    614   b  and  818   a,    618   b  of link member  608 . 
     FIG. 51 illustrates another preferred embodiment of the surgical retractor in accordance with the subject disclosure. This surgical retractor, designated generally at  700 , includes a base  702  and any one or more of the instruments shown including: retractor blade assembly  704 ; retractor blade assembly with suction/irrigation structure  706 ; retractor blade assembly with light  708 ; heart manipulator  710 ; and heart stabilizer instrument  712 . These instruments are discussed in greater detail hereinbelow. 
     Base  702  is configured in accordance with the other bases discussed above and provides a low profile mount for instrumentation used in the surgical procedure being performed. A plurality of suture mounts  714  are defined in an upper peripheral portion  716  of base  702  and serve as attachment and anchor points for suture ends  718  from the surgical field. Referring to FIGS. 52 and 53, suture mounts  714  include a tightly wound coil spring  720  positioned in a cavity  722  with the coils oriented substantially transverse to the radians of the base  702 . A triangular ramp  724  is formed on an inner radial surface of suture mount  714 . A slot  726  is formed on an outer radial surface of suture mount  714  beyond coil spring  720  and in axial alignment with ramp  724 . This ramp/slot configuration facilitates easy access to position suture end  718  in coil spring  720 . 
     The balance of base  702  is configured in substantially the same manner as previously described bases and includes teeth  728 , beveled inner peripheral surface  730  and inner lip  732 . 
     Surgical retractor blade assembly with blowing structure  706  is shown in FIGS. 54-56. Structure  706  can also be used for suction or for irrigation to remove fluids from the surgical sit. The retractor blade assembly  704  is similar to the retractor blade assembly  414  discussed in detail above. Retractor blade assembly  704  includes mounting bracket  734 , retractor blade  736  and removable retraction knob  738 . 
     As illustrated in FIG. 56, mounting bracket  734  includes housing  740  and mounting plate  742  which together form a channel through which retractor blade  736  is reciprocally slidable. 
     Retractor blade  736  includes body portion  744  and rib engaging portion  746 . Body portion  744  defines a flanged gripping handle  748  configured to be grasped by the surgeon in order to slide retractor blade  736  relative to mounting bracket  734 . Body portion  744  further defines longitudinally oriented rack gearing  750  and a series of sloping teeth  752 . Rack gearing  750  and teeth  752  are disposed along elongated cavity  754  defined in body portion  744 . 
     Teeth  752  are releasably engaged by pawl  756  mounted in housing  740 . Operation of this pawl  756  is substantially the same as pawl  460  described above in connection with retractor blade assembly  414 . 
     Rib engaging portion  746  extends distally from body portion  744  and includes an angularly depending portion including one or more strengthening ribs  758  to provide additional strength. 
     Blowing structure  760  is integrally formed into the retractor blade assembly shown in FIGS. 54-56. This structure includes a tube  762  which extends the length of the retractor blade assembly and exits the ring engaging portion  764  to access the surgical site. A tube connector  764  is positioned at a proximal end of tube  762  and connects to an appropriate source such as a vacuum or pressure source (not shown) depending on whether structure  760  is used for blowing, irrigation or suction. Forming wire  766  is positioned adjacent tube  762  and is deformable to configure tube  762  in a desired angular orientation. Alternatively, tube  762  may be remotely oriented or rotated from body portion  744  using known structure. 
     FIGS. 57 and 58 illustrate a retractor blade assembly with an integral light shown generally at  708 . The basic configuration and operation of this assembly is identical to that described above with the difference that a light  768  has been substituted for suction/irrigation structure. A wide variety of lights can be accommodated. In the illustrated embodiment, a fiber optic bundle is disposed within a longitudinally extending sheath  770 . A fiber optic couple  772  is positioned adjacent the proximal end of the assembly and can be connected to an appropriate light source (not shown). It is also envisioned that a wide variety of divergent and focusing lenses may be used to tailor the light as required by the surgeon. 
     The one-way ratchet mechanism used in these embodiments of the retractor blade assembly is shown in FIGS. 58A-C. This ratchet mechanism operates in the same manner as the ratchet mechanism discussed above with respect to FIGS. 39-40. Note that as shown in FIG. 58B, the retractor blade  736  can be pulled in the direction of the arrow to retract the bone and tissue. However, to move the retractor blade  736  in the opposite direction, i.e. the direction of the arrow of FIG. 58C, pawl  756  must be pressed in. 
     FIGS. 59-63 illustrate another embodiment of a heart stabilizer instrument  800  in accordance with the subject disclosure. Heart stabilizer instrument  800  is substantially the same as heart stabilizer instrument  500  discussed in detail above. The instrument includes frame  802 , articulating arm  804  and mounting assembly  806 . 
     Frame  802  is configured in the same manner as frame  502  and includes a pair of legs  808   a  and  808   b,  each having teeth  810  for atraumatically contacting the surface of the heart. 
     Frame  802  is connected to articulating arm  804  by connector  812 . A positioning flange  814  is formed on connector  812  and facilitates positioning of frame  802  on the heart surface either by manually grasping the flange  814  or by affixing a grasping instrument (not shown) to the flange  814  and positioning the frame in a desired location. 
     Mounting assembly  806  is mounted adjacent the articulating arm  804  and includes mounting flange member  830 , mounting base  832 , toggle housing  834 , and toggle  836 . As shown in FIGS. 61-62, mounting base  832  has a flat bottom surface  838  to rest on the top of base  702 . Mounting flange member  830  and toggle housing  834  are slidably mounted with respect to mounting base  832 . Mounting flange member  830  has flange  846  for engaging inner rim of base  702 . Toggle housing  834  has flange  848  for engaging outer rim of base  702 . 
     Toggle  836  includes cylindrical mounting pins  850  and finger loop  852 . Cylindrical mounting pins  850  are configured to be received within recess  854  defined within toggle housing  834  and to be pivotably movable therein. Cable  816  extends through articulating arm  804 . The distal end portion of cable  816  is pinned to toggle  836  by clip  856 . Biasing spring  858  is positioned in toggle housing  834  and serves to normally bias mounting flange member  830  distally relative to toggle housing  834 . 
     Handle spring member  860  is integrally formed on toggle  836  and is configured to operatively interact with protrusion  862  formed in cavity  854  of toggle housing  834 , as toggle  836  is moved into and out of approximation with toggle housing  834 . 
     FIGS. 64-66, illustrate heart stabilizer instrument  800  with cable  816  in an unlocked, unstressed configuration. As illustrated in FIG. 64, instrument  800  is placed on base  702  with mounting flange member  830  and toggle housing  834  spaced apart sufficiently to allow flanges  846  and  848  to clear inner rim  830  and outer rim  833 , respectively. 
     Toggle  836  is disposed in toggle housing  834  in an unlocked configuration, such that finger loop  852  and finger loop  853  are spaced apart. Cable  816  is loose to permit manipulation of articulating arm  804 . 
     FIG. 65 illustrates the relative position of handle spring  860  relative to protrusion  862  within toggle housing  834 . 
     FIGS. 66-67 illustrate instrument  800  with cable  816  in a first taut, locked, unstressed configuration. As depicted in FIG. 66, toggle  836  is pivoted with respect to toggle housing  834  such that finger loop  852  is moved toward finger loop  853 . The distal end of cable  816  is stressed to approximate mounting flange member  832  and mounting base  832  locking surgical instrument  500  in position on base  702 . FIG. 67 shows the progressing of toggle  836  relative to toggle housing  834  into the locked, unstressed configuration. In this position, articulating arm  804  can still be manipulated. 
     The final, locked and stressed configuration is shown in FIGS. 68-69. In this configuration, finger loops  852  and  853  have moved into close approximation simultaneously, further stressing cable  816  to maintain a preset configuration desired by the surgeon, e.g. to lock articulating arm  804  in place. Once locked into this locked-stressed configuration, the surgeon is permitted to perform other procedures without having to manually apply pressure on the heart via the heart stabilizer instrument. 
     Another preferred embodiment of the heart manipulator  900  in accordance with the subject disclosure is shown in FIG.  70 . The heart manipulator includes a manipulator portion  902 , an articulating arm  904  and a mounting assembly  906 . The structure and operation of mounting assembly  906  and articulating arm  904  are substantially the same as the heart stabilizer  800  discussed above. 
     The manipulator portion  902  includes a frame  908  supporting mesh  910  and is preferably provided with a curved section adjacent a distal end thereof to assist in manipulation of the heart. 
     FIGS. 71A and 71B illustrate a rib elevator  980  which can be mounted to the aforedescribed bases to enable the patient&#39;s rib to be lifted. Rib elevator  980  includes a set of tabs  982  which engage inner lip  732  for attachment to the base. Reinforcement ribs  984   a,    984   b  formed on the rear surface  981 , increase the rigidity of rib elevator  980  and also provide a gripping surface fur the user to flex the rib elevator  980  to facilitate attachment and removal from the base. Teeth  986  function in the same manner as the teeth  728  of base  702 , i.e. for mounting one or more of retractor assemblies  704 ,  706 ,  708 . As can be appreciated, when rib elevator  980  is mounted to base  702 , the mounted retractor assembly will be angled towards the rib so that a retraction force will be applied to the rib partially in an upward direction. This is advantageous, for example, for access and severing of the IMA. The rib elevator  980  can subsequently be removed and a retractor assembly mounted directly to the base  702  in the manner described above. 
     FIGS. 71 and 72 illustrate two preferred kit configurations in accordance with the subject disclosure. Kit  950  (FIG. 71) is formed to accommodate a basic blade retractor assembly  704 , a blade retractor assembly with suction irrigation  706 , a blade retractor assembly with light  708 , a base  702 , a retraction knob  738 , a heart stabilizer instrument  800  and/or a heart manipulator  900  therein. Cavities  952 ,  954 ,  956 ,  958  and  960  are formed in cover  962  to accommodate these elements. Cover  962  may be fixed to bottom  964  by adhesive, ultrasonic welding, heating, etc. 
     Kit  970  is substantially similar to kit  950  except that the heart stabilizer instrument  800  and the heart manipulator  900  are excluded. Cover  972  includes cavities  952 ,  958  and  960  to accommodate retractors  704 ,  706 ,  708 , base  702  and retraction knob  738 . Cover  972  and bottom  974  may be joined in the same manner as disclosed for kit  950  above. 
     Rib elevator  980  can optionally be included in the kits. 
     It will be understood that various modifications may be made to the embodiments shown herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.