Patent Abstract:
The present invention relates to a surgical retractor that immobilizes tissue at a surgical site. A preferred embodiment of the retractor is used during minimally invasive direct coronary bypass procedures to arrest movement of the grafting site while the heart continues pumping. Tape or thread can be used to connect the artery to the retractor with a holder.

Full Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of U.S. Ser. No. 09/410,982, filed Oct. 1, 1999 which is a continuation-in-part of U.S. Ser. No. 09/307,195 filed on May 7, 1999 which is a continuation application of International Application No. PCT/US98/08348, filed on Apr. 24, 1998 and designating the United States which is a continuation-in-part application of U.S. Ser. No. 08/845,333 filed on Apr. 25, 1997, the entire teachings of the above applications being incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Numerous devices have been used to position tissue at a surgical site to aid in the performing of surgical procedures. Retractors, for example, have been used 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 desired anastomosis.  
           [0003]    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) onto the left anterior descending (LAD) or other 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 minimally invasive procedure, 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 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.  
           [0004]    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 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 grafting site. The use of pharmacological agents is undesirable and impairs circulatory function. Traction by compression of the heart against the spine does serve to immobilize the site but can compromise the ability of the heart to maintain circulation and result in hypotension. Upward traction can involve circumferential compression of the artery to occlude the artery and prevent blood flow, however upward traction that is sufficient to immobilize the site can cause injury, stenosis or occlusion of the vessel.  
           [0005]    There is a continuing need however 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; safe and reliable.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention relates to a surgical retractor for immobilizing tissue at a surgical site and to a method of using the retractor during a surgical procedure. A preferred embodiment of the retractor includes a retaining element having an aperture 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 retaining element or platform so that the user can manipulate the position of the retractor as needed.  
           [0007]    In a preferred embodiment of the invention a connector such as elastic tape or thread is used to position tissue at the surgical site within the retractor aperture and to prevent movement of the tissue during the procedure. The connecting cord, thread or tape also aids in the compression of the artery in a grafting procedure to occlude flow on one or both sides of the surgical site. The cord is attached to the holder on the retaining element. A preferred embodiment of the holder can be a plurality of slits or openings positioned on both sides of the retractor that receive and frictionally secure the cord on both sides of the aperture. In another preferred embodiment a mechanical fastener is used to grip both sides of the cord. The fastener can be a spring mounted valve, for example, that allows the user to adjust the tension in the cord.  
           [0008]    A preferred embodiment of the invention comprises a retaining element or base having two sections that can be separated after the procedure is complete to permit removal of the retractor from under the grafted artery. Another preferred embodiment uses a side opening in the platform of the retractor that extends to the aperture so that the grafted artery slips through the side opening during removal. During minimally invasive direct coronary artery bypass operations, one or more surface sections of the retractor platform can be positioned against the inner surface or posterior aspect of one or both ribs adjacent to the surgical site. Thus, the size and geometry of the platform are selected to utilize the adjoining ribs where the upper surface of the platform frictionally engages the inner surface of one or more ribs to hold the retractor in a fixed position. The retractor can be beneficial in any procedure where it is necessary to stabilize a surgical site. For example, the retractor can also be used for grafting onto the diagonal, right or other coronary arteries without altering the heart&#39;s pumping function.  
           [0009]    The coronary arteries are about 1-2 mm in diameter, and the pumping heart can move these arteries over distances of several millimeters during each heartbeat. As the movement of even 1 or 2 millimeters can result in a displacement of the grafting site that can substantially interfere with effective anastomosis, it is desirable to restrain movement of the artery at the surgical site in any direction to less than 1 mm. The retractor of the present invention restrains movement in the plane of the base to less than 0.5 mm, and preferably less than 0.2 mm.  
           [0010]    In a preferred embodiment of the invention, the handle or articulating arm that is secured to the platform can be held in position by the user, attached to a frame that is fixed around the operative site or simply clipped to a drape around the site.  
           [0011]    In a preferred embodiment of the invention, the surgical retractor can be optically transmissive or transparent to allow enhanced visibility of the underlying adjacent tissue at the desired surgical site. The aperture of the retractor in accordance with the present invention, varies in size and can range from 1-3 cm in length and 5-15 mm in width.  
           [0012]    In a preferred embodiment, the surgical retractor has raised holder elements disposed in the longitudinal dimension of the retractor, each holder element having a pair of slots that frictionally grip an end of a connector such as an elastic tape or thread which extends through the aperture to attach tissue to the retractor. The surgical retractor further has run off areas on the four corners of the retractor that have a downward slope. These run off areas allow for fluid drainage during the surgical procedure to assist in maintaining the surgical field adjacent to the aperture clear of blood during the anastomosis. The four corners of the base have a gradually thinner cross-section to provide the downward slope.  
           [0013]    In a preferred embodiment, the surgical retractor includes a two-component configuration to allow the retractor to be separated after the surgical procedure is completed to permit removal of the retractor from under the grafted artery. A pair of plastic tabs extend between the two components to securely retain the components together during the procedure and to allow the surgeon to release the components following the procedure by cutting the tabs with a knife.  
           [0014]    In another preferred embodiment, the surgical retractor has slots or grooves on the bottom surface of the retractor to allow the user to place the connector such as elastic tape or thread, either under or over the retractor to position tissue at the surgical site within the retractor aperture and to prevent movement of the tissue 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 to be positioned in the desired underlying slots. 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 constricted by the tapes. Additionally, the surgeon can position the tapes at a relatively sharp angle of approach. Alternately, a wider angle of approach may be used wherein the tapes are threaded around the outer surface of the retractor 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.  
           [0015]    In a preferred embodiment, portions of the bottom surface form a slightly curved surface which extends a slight distance downwardly parallel to the lengthwise dimension of the aperture which assists in retaining the retractor in the desired position on the heart wall of the patient as it continues beating. The bottom surface that surrounds the artery and is in contact with the pericardium can be roughened or abraded to frictionally engage the pericardium around the artery and thereby locally restrict heart motion around the surgical site. There are elevated regions or protrusions such as ridges or nubs, for example, disposed on the bottom surface of the retractor to frictionally engage the pericardium wall around the surgical site.  
           [0016]    When used in a minimally invasive coronary bypass procedure, the retractor is positioned to expose the left anterior descending (LAD) artery grafting site after incision, removal of the rib section and dissection of the left internal mammary artery (LIMA) from the chest wall. A pair of cords, for example, silastic tape (i.e. a silicon elastomer) or suture thread, are passed through the myocardium at two locations flanking the artery grafting site with blunt needles. The four ends of the two cords are connected to the platform holder with sufficient tension to occlude blood flow on both sides of the operative site. The tapes compress the artery against the bottom surface of the platform while they hold the artery grafting site in a fixed position relative to the aperture. The coronary artery is opened longitudinally and the end of the mammary artery is sewn to the graft opening with multiple fine sutures. The cords are released, blood flow is restored and the anastomosis is inspected for hemostatis and other defects and the wound is closed.  
           [0017]    The platform can include tabs or cord retainers that extend into the aperture to provide a surface against which the arteries can be compressed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a perspective view of a surgical retractor in accordance with a preferred embodiment of the invention.  
         [0019]    [0019]FIG. 2 is a perspective view of a surgical site illustrating a surgical procedure.  
         [0020]    [0020]FIG. 3 is a perspective view of a surgical retractor for a grafting procedure in accordance with the invention.  
         [0021]    [0021]FIG. 4 is a bottom perspective view of a surgical retractor in accordance with the invention.  
         [0022]    [0022]FIG. 5 is a cross-sectional view of a surgical retractor during a surgical procedure.  
         [0023]    [0023]FIGS. 6A and 6B are partial cross-sectional views of a holder in accordance with the invention.  
         [0024]    [0024]FIG. 7 is a top view of a two piece retainer in accordance with the invention.,  
         [0025]    [0025]FIG. 8 is a top perspective view of another preferred embodiment of a surgical retractor in accordance with the invention.  
         [0026]    [0026]FIG. 9 is a top perspective view of another preferred embodiment of a surgical retractor in accordance with the invention.  
         [0027]    [0027]FIG. 10 is a schematic diagram illustrating a surgical procedure in accordance with the invention.  
         [0028]    [0028]FIG. 11 is a perspective view of a frame supporting a retractor in accordance with the invention.  
         [0029]    [0029]FIGS. 12A and 12B are enlarged detailed views of a surgical retractor in accordance with the invention.  
         [0030]    [0030]FIG. 13 is an enlarged detailed top view of the preferred embodiment of a surgical retractor illustrating a separated two-section configuration of the retractor.  
         [0031]    [0031]FIG. 14 is an enlarged detailed top view of the preferred embodiment of the surgical retractor shown in FIG. 13.  
         [0032]    [0032]FIG. 15 is an enlarged detailed bottom view of the preferred embodiment of the surgical retractor shown in FIG. 13.  
         [0033]    [0033]FIG. 16 is a perspective view of a preferred embodiment of a surgical retractor in a surgical site illustrating a surgical procedure in accordance with the present invention. 
     
    
       [0034]    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  
       [0035]    A preferred embodiment of the invention is illustrated in connection with FIG. 1. A retractor  10  includes a retaining element or base  12  having an aperture  16  that is positioned to expose tissue at a surgical site. The base  12  can be made with a metal or a molded plastic material. The retractor  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 the base  12 , or as described below in connection with other preferred embodiments, can be detachable.  
         [0036]    A suction tube  32  can be attached to the handle  30  or integrated therein and is used to remove material such as blood from the operative site. In this particular embodiment the tube  32  is connected at one end to a tube  34  from a suction pump and connected at a second end to a port  36  in fluid communication with a channel within tube  28  that extends around the periphery of base  12 . The peripheral tube can have small openings  38  positioned on the sides or top thereof through which fluid such as blood or other debris can be suctioned from the surgical site to maintain a clear field.  
         [0037]    A preferred embodiment of the invention can be used at a surgical site  50  such as the example illustrated in FIG. 2. In this particular procedure for a coronary graft without cardiopulmonary bypass, a section of the 4th costal cartilage or rib  56  is removed to expose a section of the LAD artery  61 .  
         [0038]    A proximal portion of the LIMA  62  is dissected from the chest wall to expose an end  65  to be grafted onto a grafting site  66  on artery  61 . Blood flow in vessel  62  can be occluded with a clamp  64 .  
         [0039]    In this example, a connector such as a pair of cords or silastic tapes  70 ,  72  are threaded through myocardium surface  78  under the artery  61  at two locations  74 ,  76  on opposite sides of the grafting site  60 . Note that the exposed surface  78  of heart  52  is undergoing substantial movement during the procedure.  
         [0040]    As seen in the reverse perspective view of FIG. 3 in which the retractor  10  has been inserted and positioned during the procedure, the retractor  10  serves to immobilize the grafting site  60  using connecting tapes  70 ,  72  which are stretched and attached to a holder mechanism including slots  20   a - 20   d  in the peripheral edge of base  12 . As described in greater detail below, the slots  20 A- 20   d  can be manually opened or closed using actuators  22   a - 22   d , respectively, to allow the user to adjust the tension in the tapes or threads.  
         [0041]    The aperture  16  extends longitudinally along the axis of artery  61 . The site  60  is preferably located in the plane of the upper surface of base  12 . The tapes  70 ,  72  exert a compressive force on the artery  61  which is pressed against a bottom surface  40  as seen in FIG. 4. More particularly, the tapes  70 ,  72  extend in a direction that is substantially perpendicular to the artery  61  axis exposed in the aperture  16 . The aperture can have a first pair of lateral sections  18   a  and  18   b  which are aligned to accommodate the positioning of tape  70  and the aperture can also have a second pair of lateral sections  18   c  and  18   d  to accommodate the positioning of tape  72 . Alternatively, holes extending through the base  12  that are separated from the aperture can be used. The holes are large enough to provide easy feed through and can be angled towards the bottom center to provide compression of the artery at lower tension of the cord.  
         [0042]    The size of the aperture can be in the range of 1-3 cm in length and 5-15 mm in width. The aperture can be narrower in the center and wider at the opposite ends to accommodate the openings or sections  18   a - 18   d.    
         [0043]    Between each pair of sections  18   a - 18   b  and  18   c - 18   d , a sidewall section of the aperture, namely tabs  24 ,  26  extend on opposite ends of aperture  16 . The tapes  70 ,  72  compress respective portions of artery  61  on opposite sides of site  60  against tabs  26 ,  24 . As seen in FIG. 4, those portions  42 ,  44  of the bottom surface  40  are in contact with artery  61  and compress it. The bottom surface that surrounds the artery and is in contact with the heart wall can be roughened or abraded to frictionally engage the heart wall around the artery and thereby locally restrict heart motion around the surgical site.  
         [0044]    In a preferred embodiment of the invention opposite ends  82  and  84  can be positioned under adjacent ribs  54  and  58 , respectively. This eliminates any substantial movement of the base  12  while the heart is pumping so that anastomosis  80  of the end  65  onto site  60  can be quickly completed. The opposite ends  82 ,  84  can be slightly raised relative to the plane of the remainder of the base  12  to provide a concave structure to enhance the frictional engagement of sections  82 ,  84  to ribs  54 ,  58 , respectively. The platform has a substantially rectangular shape with each side having a length in the range between 3.5 cm and 6 cm. Thus the surface area of the platform is between 12 cm 2  and 25 cm 2 , preferably between 14 cm 2  and 20 cm 2 . This size fits readily in the incision between the ribs and can be positioned with both ends extending under the 3rd and 5th ribs. This structure exerts little downward force on the heart or upward force on the artery while immobilizing the artery at the surgical site. Also the anterior-posterior compression of the artery avoids trauma to the artery due to circumferential compression. By engaging the ribs, the retractor is self retaining providing for easier use and manipulation.  
         [0045]    As seen in FIG. 5, the tape  76  under the bottom surface  94  of the tab  24  lifts the artery  60  to form an occlusion  86 . This view also shows the optional channel  92  extending around the periphery of base  12  that is used to irrigate or suction around the site.  
         [0046]    The fastening mechanism is illustrated in the partial cross-sectional views of FIGS. 6A and 6B. The closed position  110  is illustrated in FIG. 6A where spring  112  has expanded to move slot  116  in element  115  out of alignment with slot  114  in the outer tube. The cord  72  is displaced and frictionally grasped by the sliding movement of element  115 . The user can manually displace  118  to align slot  114  with slot  116  while compressing spring  112 . In the “open” position  120 , the cord  72  can be easily removed or pulled through to increase tension.  
         [0047]    After the procedure is complete the retractor  10  needs to be removed from the site. In the embodiment of FIG. 1, the base  12  can be formed with two sections or plates  14   a ,  14   b . As seen in FIG. 7, these components can be separated at joint  25  to allow removal of the retractor  10 . The two halves  14   a ,  14   b  can be connected with a frictional tube section  96 .  
         [0048]    In the preferred embodiment illustrated in FIG. 8, the retractor  100  can have a plurality of handle attachment sites  102 ,  104 ,  106 ,  108  so that the user can attach the handle  105  at any site to provide the most convenient access to the aperture and facilitate immobilization of other arteries. The handle can alternatively be positioned between the two cords at an orthogonal angle relative to the aperture axis and extending above the top surface of the base.  
         [0049]    In another preferred embodiment of the invention illustrated in the perspective view of FIG. 9, a retractor  140  has a handle  142 , slots  144  located in the plane of the aperture  160  to secure the cords, end sections  162 ,  164  that engage the ribs  54 ,  58 , tabs  148 ,  150  for compression of both sides of the artery at the site  60  and a side opening  146  so that the retractor can be removed.  
         [0050]    In this embodiment, the LIMA slides out through opening  146  during removal of the retractor after completion of the procedure. This unitary retractor structure  140  can also include various features described previously in connection with the embodiment of FIG. 1 including the attached or integrated suction tube, the detachable handle, the irrigation or suction channel with ports or the mechanically actuated fasteners.  
         [0051]    A preferred method of stabilizing tissue during a coronary bypass procedure  200  is illustrated in the process flow sequence of FIG. 10. A 5-8 cm sized incision is made over the 4th rib and a section of the 4th costal cartilage is removed  202 . The LIMA is dissected from the chest wall  204  and divided distally. After blood flow assessment the LIMA can be temporarily closed with a spring loaded clip.  
         [0052]    A self-retaining wound retractor is used to distract the edges of the incision and a “trap door” incision is made in the pericardium and the cut edge sewn to the skin to pull the pericardial sack and heart anteriorly. The LAD is exposed and a site suitable for anastomosis is selected for grafting  206 . Tapes are inserted in the myocardium with blunt needles approximately 1-2 cm apart  208  and the retractor is inserted  210  with the tapes being pulled through the aperture and positioned in the lateral sections thereof. The tapes are connected to the holder  212  to compress the artery  214  and occlude blood flow on both sides of the grafting site. The tension in the tapes can optionally be adjusted during the procedure to minimize blood loss at the site.  
         [0053]    The retractor is secured  216  at the site by positioning one or both ends under adjoining ribs, or alternatively, attaching the handle or arm to the wound retractor or other implement. The grafting site undergoes less than 0.1 mm of movement in any direction during this example procedure.  
         [0054]    The site is suctioned or irrigated  218  during anastomosis, the grafting site is inspected, the tapes are released from the holders, and the retractor is removed either by sliding the LIMA through a side opening in the retractor or detaching a section of the retractor to accommodate removal of the LIMA from the aperture. After blood flow is restored, the site is inspected and closed  220 .  
         [0055]    Although the use of the retractor 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 where movement at the site can interfere with the procedure.  
         [0056]    Alternative embodiments involve opening of the chest and positioning the retractor at any exposed site on the heart wall or surrounding areas to immobilize the operative site. The retractor serves to isolate the site and limits or stops motion at the site due to respiratory movement of the lungs or the pumping motion of the heart.  
         [0057]    In another preferred embodiment, a stabilizer system or frame  240  manufactured by Genzyme Surgical Products is illustrated in FIG. 11 to support a surgical retractor  260  in accordance with the invention.  
         [0058]    The frame  240  used with the invention includes a bar  242  having an arm  244  extending orthogonally from a first end and attached to a second arm  246  with a thumb screw at a second end. Each arm  244 ,  246  has a pair of mounting elements  252 ,  255  on which a pivot rod  256  can be mounted. This rod  256  can be rotated 360 degrees to any desired position such that mounting arm  245  can oriented relative to the surgical site as needed to position the retractor  260 . Each arm  244 ,  246  has a pair of grippers  248 ,  250  that engage anatomical features such as neighboring ribs at the site to stabilize the frame  240 .  
         [0059]    The mounting arm  245  supports the handle or support arm  262  with a friction fitting  258  which the user tightens with knob  268  to grip arm  262  at region  266 . The support arm  262  has a knob  264  at one end that can be turned by the user to engage a post  276  shown in FIG. 12A. A ball on the post  276  can be slipped through an opening  265  in the second end of arm  262  and locked into position using knob  264 .  
         [0060]    The post  276  can be pivoted relative to arm  262  by loosening the knob  264 , thus allowing the user to orient the retractor  260  at the site for fine positioning. The post  276  is mounted on a plastic retaining element  270  in this embodiment. The element  270  can be a transparent or opaque molded device that can be separated into two components  272 ,  274  as described previously. The two components can be attached by friction fit rods  294  that are inserted into holes in element  272 . Element  270  can be made with a transparent material to enhance visibility at the site.  
         [0061]    Both components have raised holder elements  284 ,  286 . Element  284  has a pair of slots  288 ,  289  that each frictionally grip an end of a cord which extends through the aperture  278  to attach tissue to the retractor. The second end of each cord is gripped by corresponding slots  290 ,  292  in element  286 .  
         [0062]    Tabs or cord retainers  280 ,  282  are integrally formed with component  274  and function as described previously. In the detailed partial view of FIG. 12B, the front inclined surface can be formed at a shallower angle such that the top ridge  279  is narrower. This embodiment of cord retainer  281  affords easier insertion of cords into the aperture.  
         [0063]    This embodiment can also be formed with integral suction channels or openings in the top surface of the element  270 . A suction tube can be attached through or with the arm  262  or attached to a suction port on element  270 .  
         [0064]    [0064]FIG. 13 illustrates an enlarged detailed top view of a preferred embodiment of the surgical retractor. A retractor  300  includes a retaining element or base  312  having an aperture  316  that is positioned to expose tissue at a surgical site. The base  312  can be made with metal or a molded plastic material. The retractor can be used on multiple vessels for the same patient, can be sterilized and reused on additional patients as desired, or can be disposed of after each use.  
         [0065]    The size of the aperture  316  can be in the range of 1-3 cm in length and 5-15 mm in width. The aperture  316  can be narrower in the center and wider at the opposite ends to accommodate the opening required for the surgical site. The aperture  316  can have a first pair of lateral sections  320   a  and  320   b  which are aligned to accommodate the positioning of a first connector such as tape or thread and the aperture can also have a second pair of lateral sections  320   c  and  320   d  to accommodate the positioning of a second connector such as tape or thread. A connector such as a pair of cords or silastic tapes are threaded through myocardium surface under an artery at two locations on opposite sides of the grafting site.  
         [0066]    Between each pair of sections  320   a -  320   b  and  320   c  and  320   d , a sidewall section of the aperture, namely tabs  322 ,  324  extend on opposite ends of aperture  316 . The aperture can also have longitudinally extending angled sidewalls  325   a ,  325   b , that descend at an oblique angle into the aperture. The angled sidewalls  325   a ,  325   b , as well as the angled upper surfaces of tabs  322 ,  324  aid in providing better access to the surgical site. The oblique angle extends from the plane of the upper surface containing surface regions  327   a ,  327   b  to the surfaces of sidewalls  325   a ,  325   b . The tapes extend through the heart tissue adjacent to the artery and compress respective portions of an artery on opposite sides of site  60  against tabs  322 ,  324  as the tapes are tightened by the surgeon.  
         [0067]    The surgical retractor has raised holder or sidewall elements  326 ,  328 . Element  326  has a pair of slots  330 ,  332  that each frictionally grip an end of a cord which extends through the aperture  316  to attach tissue to the retractor. The second end of each cord is gripped by corresponding slots  334 ,  336  in element  328 .  
         [0068]    There are run off areas  338   a -  338   d  on the corners of the retractor that have a downward slope. These run off areas allow for fluid drainage during the surgical procedure to assist in maintaining the surgical field adjacent to the aperture  316  clear of blood during the anastomosis. The four corners of the base  312  have a gradually thinner cross-section to provide the downward slope. The top surface of the base  312  can have two substantially planar areas  327   a ,  327   b  which extend between the angled sidewalls  325   a ,  325   b  and the corresponding holder elements  326 ,  328  which extend in a direction orthogonal to the plane of the upper surface of base  312 . Additionally the upper surface of base  312  has endwalls  329   a ,  329   b ,  329   c ,  329   d  at both ends of the aperture. The endwalls  329   a - d  combined with raised sidewall elements  326 ,  328  define the openings  338   a - d.    
         [0069]    A post  340  is used with the frame  240  shown in FIG. 11 to allow the user to orient the retractor  300  at the site for fine positioning. The post  340  is mounted on the plastic retaining element  342  in this embodiment. Element  342  can be made with a transparent material to enhance visibility of the underlying adjacent tissue at the desired surgical site or can be an opaque molded device. The element  342  can be separated into two components  344 ,  346 . The two components  344 ,  346  can be attached by fit rods  348 , or similar retaining mechanisms, that are inserted into holes in element  346 . In a preferred embodiment of this invention, a pair of plastic tabs  347  or bridge-type members extend between the two components,  344  and  346 . The plastic tabs  347  can be welded or snapped into place to securely retain the components together during the procedure and to allow the surgeon to release the components following the procedure by cutting the tabs  347  with a knife.  
         [0070]    [0070]FIG. 14 illustrates an enlarged detailed top view of the surgical retractor  300  showing the combined two-component  344 ,  346  configuration. The two-component  344 ,  346  configuration of the preferred embodiment of the surgical retractor allows the retractor to be separated after the surgical procedure is completed to permit removal of the retractor  300  from under the grafted artery.  
         [0071]    [0071]FIG. 15 illustrates an enlarged detailed view of the bottom surface  360  of the preferred embodiment of the surgical retractor  300 . The portions  362 ,  364  of the bottom surface  360  are in contact with an artery and form a slightly curved surface which extends a slight distance downwardly parallel to the lengthwise dimension of the aperture  316 . The addition of the curved bottom surface  360  in combination with the elevated regions  366 , described below, further assist in retaining the retractor in the desired position on the heart wall of the patient as it continues beating. The bottom surface  360  that surrounds the artery and is in contact with the pericardium can be roughened or abraded to frictionally engage the pericardium around the artery and thereby locally restrict heart motion around the surgical site. There are elevated regions  366  or protrusions such as ridges or nubs for example, disposed on the bottom surface  360  of the retractor to frictionally engage the pericardium.  
         [0072]    A preferred embodiment may have slots or grooves  368   a -  368   d  as shown in FIG. 15 on the bottom surface  360  of the retractor to allow the user to place the tapes either under or over the retractor for subsequent securement. When these slots are used, the tapes are threaded through the tissue of the heart wall of the patient and then aligned to be positioned in the desired underlying slots. The tapes are then grasped and lifted around the outer surface of the holder elements  326  and  328  and then positioned in the desired slots  330 ,  332 ,  334 ,  336 . This feature allows the surgeon to 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 constricted by the tapes. Additionally, this feature allows the surgeon to position the tapes at a relatively sharp angle of approach. The tapes are then threaded through the aperture and into the desired slots. Alternately, a wider angle of approach may be used wherein the tapes are threaded around the outer surface of the retractor so that more tissue may be positioned between the tapes and the blood vessel. The route used by the surgeon will vary depending on the depth of the desired blood vessel and the surgeon&#39;s preferred approach to performing the anastomosis.  
         [0073]    [0073]FIG. 16 illustrates a transparent surgical retractor positioned in the surgical site  380 . The retractor  300  has been inserted and positioned during a procedure for a coronary graft without a cardiopulmonary bypass, a section of the 4 th  costal cartilage or rib  382  is removed to expose a section of the LAD artery  384 . The retractor  300  serves to immobilize the grafting site  386  and is preferably used in combination with the connecting tapes  388 ,  390  which are stretched and attached to a holder mechanism including slots  330 ,  332 ,  334 ,  336  in the peripheral edge of base  312 .  
         [0074]    The aperture  316  extends longitudinally along the axis of the artery  384 . The site  380  is preferably located in the plane of the upper surface of base  312 . The tapes  388 ,  390  exert a compressive force on the artery  384  which is pressed against the bottom surface  360  as seen in FIG. 15. More particularly, the tapes  388 ,  390  extend in a direction that is substantially perpendicular to the artery  384  exposed in the aperture  316 .  
         [0075]    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 defined by the appended claims.

Technology Classification (CPC): 0