Abstract:
The present invention relates to a stabilizer that immobilizes tissue at a surgical site wherein the device includes a stabilizer having a base portion with elongate extending members that surround the sides of an aperture area and an end portion which is removable from the base portion and which surrounds the remaining side of the aperture area and wherein the stabilizer is preferably used in combination with a pair of flexible connectors that are threaded through the tissue adjacent to the aperture area to draw the tissue into contact with the aperture area of stabilizer and into contact with a pair of tab members extending from the bottom surface of the stabilizer such that the flow of blood through a blood vessel is occluded by tab members when the flexible connectors are releasably attached to the stabilizer.

Description:
The present application is a continuation in part of U.S. Ser. No. 09/410,982 filed on Oct. 1, 1999 (pending). 
    
    
     BACKGROUND OF THE INVENTION 
     Numerous devices have been used to position tissue at a surgical site to aid in the performing of surgical procedures. Various retractors or similar devices, have been used for many years to hold an artery in position during operations adjacent to the heart to prevent movement of the artery. This serves to minimize the risk of injury to the artery and adjacent tissue and can facilitate the creation of the desired anastomosis. 
     A recently developed procedure, referred to as the minimally invasive direct coronary artery bypass procedure, has been used to graft onto a coronary artery without cardiopulmonary bypass. This procedure involves the grafting of the left internal mammary artery (LIMA) or saphenous vein onto the left anterior descending (LAD) or other coronary artery. As this procedure does not require the use of a heart lung machine to oxygenate and pump blood, the morbidity and mortality associated with this procedure is substantially lower than previous bypass techniques. A problem associated with the less invasive procedures, however, is that while the heart continues to pump during the procedure, the motion of the heart can interfere with the surgeon&#39;s task of attaching the LIMA or saphenous vein to the LAD. There is also a need to stop blood flow in the area of the graft to maintain a clear field of view and provide precise suture placement. 
     Two basic strategies have been employed to address the problem of operating on a moving site, one being the use of pharmacological agents to limit heart motion, and the other being mechanical, such as a two prong retractor that is pushed down against the heart on both sides of the artery, or alternatively, upward traction away from the moving heart by suction, traction tape or suture thread. Both of these options, however, have problems associated with them. Both options are susceptible to some movement of the vessel graft site. The use of pharmacological agents is undesirable and may impair circulatory function. Traction by compression of the heart requires an increased amount of downward force on the tissue of the heart along a relatively large surface area. Although this type of device does serve to immobilize the tissue at the surgical site, it may also compromise the ability of the heart to maintain circulation and result in hypotension. Upward traction through the use of suction requires that the entire surface of the device be in contact with the tissue of the heart along a relatively large surface area to maintain suction. As with the compression type of devices, the suction type of device may cause injury, stenosis or occlusion of the vessel when upward traction that is sufficient to immobilize the tissue along the surgical site is used. Additionally, because various surfaces of the heart need to be accessed, it is not always possible or convenient to apply compression or upward traction to each surface of the heart. 
     There is a continuing need for improvement in devices and methods for retaining tissue at surgical sites to further reduce the risks associated with surgical procedures where the devices and methods are inexpensive, versatile, safe and reliable. The increased use of the above-described mechanical devices have also illustrated the need for a device that provides the desired local stabilization while allowing the surgeon to quickly set up and remove the stabilizing device while also providing access to multiple locations and surfaces on the heart of the patient. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a cardiac stabilizer for immobilizing tissue at a surgical site and to a method of using the stabilizer during a surgical procedure. A preferred embodiment of the stabilizer includes a generally ovoid or elongate retaining element or platform having an aperture area that exposes the surgical site and a holder that is used to position tissue at the surgical site relative to the retaining element. A handle can be attached to or fabricated with the platform so that the user can manipulate the position of the stabilizer as needed. As used herein, the stabilizer generally refers to a device that is movable into a contacting relationship with the tissue of a patient to reduce the movement of the tissue at the desired surgical site. 
     The coronary arteries are typically about 1-2 mm in diameter, and the pumping heart can move these arteries over distances of several millimeters during each heartbeat. Because the movement of even 1 or 2 millimeters can result in a displacement of the grafting site that can substantially interfere with suturing an effective anastomosis, it is desirable to restrain movement of the artery at the surgical site in any direction to less than about 1 mm. The stabilizer and tapes of the present invention preferably restrain movement of the tissue relative to the stabilizer. 
     A preferred embodiment of the invention comprises a retaining element or stabilizer that includes a removable end piece that is removable to form an aperture area that is open to permit removal of the stabilizer from around the grafted artery following the procedure. The end piece is used to contribute to the stability of the stabilizer during the procedure and then is readily removable to allow for the passage of the grafted vessel therethrough. The stabilizer can be beneficial in any procedure where it is desirable to stabilize tissue at a surgical site. For example, the stabilizer can also be used for grafting vessels onto the diagonal, right or other coronary arteries without altering the heart&#39;s pumping function or during surgery on various other organs or tissues. 
     In a preferred embodiment of the invention, a handle or articulating arm may be secured to the platform of the stabilizer and may be held in position by the user, attached to various locations on a retractor frame that is fixed around the operative site or simply clipped to a drape around the site. 
     In yet another preferred embodiment of the present invention, the stabilizer includes a generally ovoid or elongate shape wherein the lengthwise dimension of the stabilizer is greater than the width dimension. In this form of the invention, the connector for attachment to a handle or other member is located on the stabilizer generally along the an end portion of the stabilizer such that the application of force along the handle is applied over the blood vessel that is to be operated on and near the aperture area. 
     In a further preferred embodiment, the stabilizer has tape holder elements disposed in the longitudinal dimension and/or along the periphery of the stabilizer. Each holder element includes one or more slots that frictionally grip an end of a connector such as elastic tape or thread which extends through the tissue of the patient to connect the tissue to the stabilizer. The use of slots or grooves on the surface of the stabilizer allows the user to place the connectors such as elastic tape or thread around the outer surface of the stabilizer to position tissue at the surgical site within the stabilizer aperture and to minimize movement of the tissue relative to the stabilizer during the procedure. When these slots are used, the tapes are threaded through the tissue of the heart-wall of the patient and then aligned and drawn towards each other to be positioned in recessed areas along the periphery of the stabilizer. When the tapes are located in the recessed areas, the tapes are then drawn away from each other to be positioned in the desired retaining slots on the holding members. The surgeon can include additional tissue around the blood vessel as the tapes are tightened so that the blood vessel is compressed by the adjacent tissue rather than being directly constricted by the tapes. Additionally, the surgeon can position the tapes at a relatively wide angle of approach when the tapes are threaded around the outer surface of the stabilizer so that more tissue is positioned between the tapes and the blood vessel. The route used by the surgeon varies depending on the depth of the desired blood vessel and the surgeon&#39;s preferred approach to performing the anastomosis. The combination of the stabilizer and the tapes provides a system that does not require the significant compression or upward traction as required by the prior devices to obtain a suitable surgical site. 
     In a further preferred embodiment, the stabilizer may also include a plurality of tabs extending downwardly from the bottom surface of the stabilizer along the ends of the aperture area. The use of the tabs in combination with the tapes causes the tissue in the aperture area to be raised upwardly a small amount to expose the portion of the blood vessel that is to be the subject of the anastomosis. Additionally, the tabs preferably extend downwardly from the ends of the aperture area to create contact surfaces along the ends sides of desired surgical site to further restrict the flow of blood through the blood vessel during the procedure. 
     When the present invention is used in a coronary artery bypass procedure, the stabilizer is positioned in a desired position along the myocardial surface of the patient. One or more tapes, for example, silastic tape (i.e. a silicon elastomer) or suture thread, are passed through the myocardium at a location adjacent to the artery grafting site with a blunt needle. The stabilizer is then loosely positioned in the desired relative position along the myocardium of the patient. Both ends of each tape are connected to the stabilizer platform with sufficient tension to draw the tissue into contact with the bottom surface of the platform and to occlude blood flow on the upstream side of the operative site. The stabilizer is then securely positioned in the desired relative position along the myocardium of the patient. The tape compresses the artery against the bottom surface of the platform and preferably against the tabs while the artery graft site is held in a fixed position relative to the aperture area. The coronary artery is opened longitudinally and the end of the mammary artery or other blood vessel is sewn to the graft opening with multiple fine sutures. Once the graft is completed, the end portion of the stabilizer may be removed to open the aperture area. The tape may then be released to restore blood flow to the blood vessel and the anastomosis is then inspected for hemostasis and other defects. The anastomosis is then readily removable from the end of the stabilizer through the open end of the aperture area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top perspective view of a stabilizer in accordance with the preferred embodiment of the invention; 
     FIG. 2 is a bottom perspective view of the stabilizer in accordance with the preferred embodiment of the invention; 
     FIG. 3 is a top perspective view of the stabilizer in accordance with the preferred embodiment of the invention having the end portion removed; 
     FIG. 4 is a bottom perspective view of the stabilizer in accordance with the preferred embodiment of the invention having the end portion removed; 
     FIG. 5 is a top perspective view of the end portion of the stabilizer in accordance with the preferred embodiment of the invention; 
     FIG. 6 is an enlarged top view of the end portion of the stabilizer in accordance with the preferred embodiment of the invention; 
     FIG. 7 is an end perspective view of the stabilizer in accordance with the preferred embodiment of the invention showing the tab members in the aperture area and schematically illustrating the compression of a blood vessel; 
     FIG. 8 is a perspective view of a chest retractor and handle supporting a stabilizer in accordance with the invention; and 
     FIG. 9 is a schematic diagram illustrating a surgical procedure in accordance with the preferred form of the present invention. 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A preferred embodiment of the invention is illustrated in connection with FIG. 1. A stabilizer  10  includes a platform or base  12  having an aperture area  16  that is closed by a removable end portion  32 . The aperture area  16  is positioned in use to expose tissue at a surgical site. The stabilizer  10  can be made with nearly any material, including a metal or a molded plastic material. The stabilizer  10  can be sterilized after each use, or alternatively, can be disposable after one procedure. A handle  30  or articulating arm can be permanently attached to a connector  24  on the base  12  of the stabilizer  10 , or as described below in connection with other preferred embodiments, can be detachable. 
     In a preferred embodiment of the invention, the platform has a substantially ovoid or elongate shape with each side having a width in the range between about 0.75 cm. and 2 cm. and a length in the range of about 3.0 cm and 6 cm. Thus the surface area of the platform is between about 2.25 cm 2  and 12 cm 2 , preferably between about 5 cm 2  and 10 cm 2 . This size fits readily in the incision in the chest of the patient either during typical open chest surgery or less or minimally invasive surgery and can be positioned along nearly any surface of the heart. The upper surface of the base  12  of the stabilizer  10  preferably includes a raised lip area  18  substantially surrounding the sides of the stabilizer  10  and a plurality of spaced apart and raised upstanding holder members  20  having slots  22  associated therewith. As shown, a plurality of drainage areas  19  may be located along the lengthwise dimension of the base to allow fluids to drain from the base  12  during the procedure. A connector  24 , such as a ball member, is positioned along the proximal side of the base  12  of the stabilizer  10  and is spaced apart from the aperture area  16 . In the preferred form of this invention, the connector  24  is positioned adjacent to the lip area  18  and is releasably attachable to a handle member  30 . The remaining distal side of the stabilizer  10  includes a releasable end portion  32  to enclose the aperture area  16 . 
     Additionally, the base  12  preferably includes a plurality of pairs of spaced apart recessed areas  38  and  40  on the sides thereof. The pairs of recessed areas  38  and  40  preferably extend inwardly from the periphery of the base  12  and are aligned generally with the tab members  34  and  36  the ends of the aperture area  16 . As shown, the pairs of the recessed areas  38  and  40  preferably decrease in width and curve a small amount inwardly from the periphery of the stabilizer to allow the tapes  70  to be threaded therein. The tapes  70  may be made of nearly any material such as suture, thread or SILASTIC, stretchable material. The recessed areas  38  and  40  assist in retaining the tapes in the desired position prior to threading the tapes into the holding mechanisms  20 . In this embodiment, the user may pull the tapes toward the respective ends of the stabilizer to diagonally thread the tapes into the recessed areas  38  and  40 . The width of the pairs of recessed areas  38  and  40  are sized to removably and readily receive the connecting tapes  70  therein. The inner surface of the recessed areas are also preferably aligned with the holder members  20  and slots  22  located along the exterior surface of the stabilizer  10  and the distal and proximal ends of the aperture area  16 . 
     The size of the aperture area  16  can be in the range of about 0.1 and 2 cm. in width and about 0.5 and 5 mm in length. The aperture area  16  can be of various configurations including, wider in the center and narrower at the ends adjacent to the connector  24  and the end portion  32  as shown in the preferred form of the present invention. In the preferred form of the present invention, the sides of the aperture area  16  are slightly curved to provide a wider area at the center of the aperture area than at the ends of the aperture area to assist in framing the surgical site for the surgeon as the tissue is exposed. As shown, the aperture area  16  of the stabilizer is formed to include a proximal side and lateral sides that are formed as part of the base  12  and the distal side that is formed by the removable end portion  32 . As referenced above, the combined use of the tapes  70  and the tab members  34  and  36  cause the tissue to extend upwardly a small amount into the aperture area. 
     The distal end portion of the base includes a contact area  42  extending along each side of the aperture area  16 . The contact area  42  includes a pair of generally flat, inwardly extending surfaces thereon for the frictional receipt of the end portion  32  thereon. Additionally, a suture hole  44  is located along one side of the contact area to receive a suture  48  that is threaded through a similar suture hole  46  located on the end portion  32 . The suture holes  44  and  46  allow the end portion  32  to be fixedly attached to the base  12  via a suture  48  that is threaded through the suture holes  44  and  46 . The use of the suture  48  and suture holes reduce the likelihood that the end portion  32  may become disengaged from the base prematurely during the surgical procedure. Once the anastomosis is completed, the surgeon may cut the suture  48  using a blade or other instrument. 
     The end portion  32  of the stabilizer  10  is sized to be frictionally received on the distal end of the base  12  and to close the distal end of the aperture area  16 . The end portion  32  forms the distal end of the aperture area  16  and includes a top raised lip area  50  along the outer periphery thereof that fits adjacent to the raised lip area  18  of the base  12  and the pair of recessed areas  40 . The suture hole  46  and a cutting slot  52  are positioned on the top surface of the end portion  32 . The cutting slot  52  is located between the suture hole  44  and suture hole  46  to provide the surgeon with an elongate recess to cut the suture  48  in. The sides of the end portion  32  also include upper and lower extensions,  54  and  56  that are sized and positioned to frictionally receive the contact area  42  from the base  12  therein so that the end portion is frictionally retained on the base even after the suture  48  is cut by the surgeon. Although the end portion is preferably frictionally retained on the base  12 , it is anticipated that various other mechanisms may be used, such as clips, adhesives or other temporary retaining members. As shown, the upper extensions  54  from the end portion  32  preferably extend inwardly from the raised lip area  50  while the lower extensions  56  extend inwardly and function to guide and retain the contact areas  42  of the base  12  in the desired position. The end portion  32  may also preferably includes a radio-opaque marker  58  thereon or may include radio-opaque materials therein to enable the surgeon to located the end portion  32  of the stabilizer in the event that the end portion is accidentally separated from the base  12  during the procedure. 
     The bottom surface  14  of the stabilizer  10  includes a pair of tab members  34  and  36  extending downwardly therefrom. The tab members  34  and  36  are preferably shaped as elongate tapered members that taper downwardly and extend from the bottom surface  14  of the stabilizer  10  along the proximal and distal ends of the aperture area  16 . The tab members  34  and  36  are also preferably longer than they are wide and are aligned generally perpendicular to the lengthwise dimension of the aperture area  16  and the intended alignment of the blood vessel. In use, tab member  34  is positioned to reduce blood flow from the blood vessel into the surgical site formed by the aperture area  16 . The tab member  36  is positioned on the bottom surface of the end portion  32  and is oriented to be positioned downstream of the surgical site formed by the aperture area  16  to prevent the back flow of blood from the blood vessel. In the preferred form of the present invention, the tab member  36  is formed to extend at least partially from the bottom surface of the end portion  32 . A plurality of spaced apart gripping surfaces  60  are also located on the bottom surface  14  of the base to assist in maintaining contact between the tissue of the patient and the stabilizer  10 . 
     Alternately, the bottom surface  14  of the base  12  that is in contact with the myocardium may be roughened or abraded to frictionally engage the heart wall around the artery and thereby locally restrict heart motion around the surgical site. 
     In the preferred embodiment of the present invention, the stabilizer  10  can have a connector  24 , such as a ball member from a ball and socket connection, or a similar handle attachment mechanism so that the user can attach a handle  30  to the stabilizer  10  to provide convenient access to the aperture area  16  and facilitate immobilization of the tissue surrounding the artery. The connector  24  can be located along the proximal end portion of the base and is positioned between or adjacent to the tapes relative to the aperture area and also preferably extends above the top surface of the stabilizer  10 . This structure exerts little downward force or upward force on the heart on the artery while immobilizing the tissue at the surgical site. Also the anterior-posterior compression of the artery avoids trauma to the artery due to circumferential compression. As shown, the tapes  70  under the bottom surface of the tabs  32  and  36  lifts the artery to form an occlusion by compressing the artery between the tissue captured by the tape and the bottom surface of the stabilizer  10 . 
     A preferred embodiment of the invention can be used at a surgical site to perform an anastomosis during a bypass procedure. In this particular procedure for a coronary graft without cardiopulmonary bypass, a proximal portion of the LIMA is dissected from the chest wall to expose an end to be grafted onto a grafting site on the coronary artery. Alternately, the saphenous vein may be harvested from a leg of the patient for use as the bypass conduit. The exposed surface of heart is undergoing substantial three-dimensional movement during the procedure as the heart is allowed to continue beating in the usual manner. Blood flow in the vessel can be occluded with a clamp. In this example, a connector such as a suture, thread, cord or silastic tape  70  is threaded through myocardium surface under the coronary artery on opposite sides of the desired grafting site. The stabilizer  10  preferably serves to immobilize the grafting site using the platform portion of the stabilizer and the connecting tape  70  which is stretched and attached to a holder member  20  including one or more slots  22  in the peripheral edge of base  12 . As described in greater detail below, the ends of the tapes  70  can be manually positioned in the slots  22  to allow the user to adjust the tension in the tapes or threads. The stabilizer  10  is also preferably secured at the site by attaching the stabilizer to the handle  30  or arm and to a chest retractor or other implement. Therefore, the grafting site preferably undergoes a minimal amount of movement relative to the stabilizer in any direction during the surgical procedure. 
     In the preferred procedure as diagrammatically illustrated in FIG. 9, the tapes  70  are inserted in the myocardium with a blunt needle approximately 1-2 cm apart. The tapes are inserted into the myocardium beneath the desired coronary artery a sufficient distance to include a portion of the tissue adjacent to the artery so that the artery is not excessively constricted during the following procedure. The stabilizer  10  is initially positioned loosely adjacent to the desired surgical site. Once the tapes  70  are pulled through the tissue, the tapes are threaded into the respective recessed areas  38  and  40  on the exterior of the stabilizer  10 . The stabilizer is then moved into the desired position and the tapes  70  are tensioned through the recessed areas  38  and  40  to draw tissue against the tab members  34  and  36  up into the aperture area  16 . The tensioned tapes are then connected to the slots  22  of the on the holding members  20  of the stabilizer  10  to compress the artery and occlude blood flow distally or upstream of the grafting site and proximally or down stream of the grafting site. The stabilizer  10  is then locked into the desired positioned adjacent to the desired surgical site to assist in the retention of the desired tissue in the aperture area  16  by locking the stabilizer  10  relative to the handle  30  and relative to the chest retractor. The tension in the tapes can be adjusted during the procedure to minimize blood loss at the site and to temporarily verify the flow of blood through the grafted blood vessel. 
     After the procedure is complete, the stabilizer  10  may be easily removed from the surgical site. In the preferred embodiment, the suture  48  may be cut and the end portion  32  may be removed from the base  12 . The tapes  70  may then be released from the slots  22 . Once the end portion  32  is removed and the tapes are released, the base  12  includes an open ended aperture area  16  to enable the completed anastomosis to be removed therefrom. This is accomplished by releasing the stabilizer from the locked position relative to the handle  30  and/or the chest retractor and moving the base  12  of the stabilizer relative to the anastomosis. Thereafter, the stabilizer may be reused on another location of the heart by the surgeon. The stabilizer  10  may be reused on the same patient by retying a portion of suture through the suture holes  44  and  46 . The stabilizer  10  may then be moved to the next desired location on the heart of the patient and the steps set forth above may be repeated. 
     Although the use of the stabilizer has been described in connection with a particular bypass procedure, it can also be used in other procedures such as bypass operations involving the diagonal, right or other coronary artery or in surgery for other organs or tissues where movement at the site can interfere with the procedure. 
     Alternative embodiments involve opening of the chest and positioning the stabilizer at any exposed site on the heart wall or surrounding areas to immobilize the operative site. The stabilizer serves to isolate the site and limits motion at the surgical site due to respiratory movement of the lungs or the pumping motion of the heart. 
     In the preferred embodiment, a retractor system or frame manufactured by Genzyme Surgical Products is illustrated in FIG. 8 to support a stabilizer in accordance with the invention. 
     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.