Abstract:
A method of and a system for treatment of atrial tachyarrhythmias. The system includes a set of hemostats having elongated opposing jaws carrying mechanisms for applying ablation energy along the jaws. The jaws having straight and curved configurations selected to allow arrangement of the jaws of along opposite sides of walls of a patient&#39;s atrium. Treatment is accomplished by applying of ablation energy to the walls of a patient&#39;s artria to create lines of lesion corresponding generally to incisions employed in a Maze type procedure.

Description:
RELATED US APPLICATION DATA  
       [0001]    This application claims priority from U.S. Provisional Patent Application No. 60/286,953, filed Apr. 26, 2001, incorporated herein by reference in its entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to surgical tools and procedures generally and relates more particularly to the use of electrosurgical ablation to treat atrial fibrillation.  
           [0003]    In patients with chronic atrial fibrillation having tachycardia that resistant to medical treatment, the Maze III procedure has been employed. This procedure controls propagation of the depolarization wavefronts in the right and left atria by means of surgical incisions through the walls of the right and left atria. The incisions create blind or dead end conduction pathways, which prevent re-entrant atrial tachycardias from occurring. While the Maze procedure is successful in treating atrial fibrillation, the procedure is quite complex and is currently practiced by only a few very skilled cardiac surgeons in conjunction with other open-heart procedures. The procedure also is quite traumatic to the heart, as in essence the right and left atria are cut into pieces and sewed back together, to define lines of lesion across which the depolarization wavefronts will not propagate.  
           [0004]    It has been suggested that procedures similar to the Maze procedure could be instead performed by means of electrosurgical ablation, for example, by applying RF energy to internal or external surfaces of the atria to create lesions across which the depolarization wavefronts will not propagate. Such procedures are disclosed in U.S. Pat. No. 5,895,417, issued to Pomeranz, et al., U.S. Pat. No. 5,575,766, issued to Swartz, et al., U.S. Pat. No. 6,032,077, issued to Pomeranz, U.S. Pat. No. 6,142,944, issued to Swanson, et al. and U.S. Pat. No. 5,871,523, issued to Fleischman, et al, all incorporated herein by reference in their entireties. Hemostat type electrosurgical or cryo-ablation devices for use in performing such procedures are described in U.S. Pat. No. 5,733,280 issued to Avitall, U.S. Pat. No. 6,237,605 issued to Vaska, et al, U.S. Pat. No. 6,161,543, issued to Cox, et al., PCT published Application No. WO99/59486, by Wang and in pending U.S. patent application Ser. No. 09/747,609 filed Dec. 22, 2000 by Hooven, et al., all incorporated herein by reference in their entireties. In order for such procedures to be effective it is desirable that the electrosurgically created lesions are continuous along their length and extend completely through the tissue of the heart. These goals may be difficult to accomplish employing dry ablation electrodes or electrodes applied only to the interior or exterior surfaces of the heart tissue.  
         SUMMARY OF THE INVENTION  
         [0005]    According to the present invention, a maze type procedure may be performed using a set of bipolar electrosurgical hemostats, which apply ablation energy (e.g. RF energy) across the walls of the left and right atria by means of delivery means (e.g. electrodes) located on either side of the atrial walls. In a preferred embodiment of the invention, the hemostats are provided with elongated RF electrodes having various straight and curved configurations. In the particular embodiment of the invention described herein, a collection of straight and curved bipolar electrosurgical hemostats is provided in order to allow the physician to produce lines of lesion that approximate the incisions that would occur during the Maze III procedure as described in the book ‘ Cardiac Surgery Operative Technique ’ by Donald B. Doty, M. D. at pages 410-419, incorporated herein by reference in its entirety, and hereafter referred to as the “Doty reference”. Other specific sets of hemostats may correspondingly be provided according to the invention to allow approximation of lines of lesion of the incisions that would be provided by other forms of the Maze procedure.  
           [0006]    The invention as disclosed herein is describing the context of an open chest surgery, with patient undergoing cardiopulmonary bypass. As described, the procedure does include a limited number of surgical incisions, in conjunction with the creation of various straight and curved lesions using the bipolar electrosurgical hemostat set of the present invention. However, the present invention is also believed applicable to closed chest procedures, in which the heart is observed thoracoscopically and access is provided by means of thoracoscopic surgical ports. It is believed that ultimately, the invention may also applicable to closed chest, beating heart surgery, dispensing with the necessity of cardiac bypass. 
       
    
    
     A BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1A illustrates a first embodiment of an electrosurgical hemostat according to the present invention having two elongated generally straight jaws.  
         [0008]    [0008]FIG. 1B illustrates an alternative configuration for the tips of the jaws of the hemostat illustrated in FIG. 1A.  
         [0009]    [0009]FIGS. 2A, 2B,  2 C and  2 D all illustrate cross section through alternative configurations for electrodes carried by the jaws of the hemostat illustrated in FIG. 1A.  
         [0010]    [0010]FIGS. 3A and 3B illustrate top and side views of a second electrosurgical hemostat according to the present invention.  
         [0011]    [0011]FIGS. 4A and 4B illustrate top and side views of a third electrosurgical hemostat according to the present invention.  
         [0012]    [0012]FIGS. 5A and 5B illustrate top and side views of a fourth electrosurgical hemostat according to the present invention.  
         [0013]    [0013]FIGS. 6A through 6M are a series of drawings illustrating schematically the surgical procedure performed using the electrosurgical hemostats of the present invention and illustrating schematically the various incisions and lesions produced according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    The invention as disclosed in the present application includes a set of four pre-configured straight and curved hemostats, particularly optimized for performing an electrosurgical procedure mimicking the incisions provided according to Maze III surgical procedure. The set of hemostats is described in more detail below.  
         [0015]    [0015]FIG. 1A illustrates a top plan view of the first of the four hemostats provided to the present invention. The hemostat may be approximately 31 centimeters in overall length as illustrated at B2, with draws of approximately 8 centimeters in length, as illustrated at A 1 .  
         [0016]    The hemostat includes two elongated handle members  12  and  14 , each provided with a finger loop at its proximal end. A conventional hemostat locking mechanism  14  is also provided. The handles of the hemostat may be fabricated of stainless steel or other readily resterilizable material. Alternatively, the handles  11  and  12  might be fabricated of a biocompatible plastic and/or the hemostat may be disposable.  
         [0017]    To the jaws  18  and  19  of the hemostat extend distally from the pivot or hinge  16 , and carry elongated electrosurgical electrodes  24  and  25 . When the jaws are parallel to one another, electrodes  25  and  25  are preferably spaced approximately 0 to 7 mm from one another, more preferably 1 to 5 mm from one another, to facilitate uniform contact allng opposite sides of a patient&#39;s atrial wall. In use, the atrial wall is compressed between electrodes  24  and  25 , and R-F energy is applied between the electrodes in order to create an elongated continuous lesion extending through the cardiac tissue. Using the hemostat of FIG. 1A, a linear lesion is produced.  
         [0018]    The electrodes  24  and  25  are preferably configured to allow fluid—assisted tissue ablation, of the type generally described in U.S. Pat. No. 6,096,037, U.S. Pat. No. Mulier, incorporated herein by reference in its entirety. To this end, each of the electrodes is provided with an electrical conductor,  20 ,  23  allowing delivery of R-F electrical energy to the electrodes  24  and  25 , respectively and with a fluid lumen  21 ,  22  allowing for delivery of saline solution or other conductive fluid to and along the length of electrodes  24  and  25 . Various alternative embodiments of the electrodes and jaws of the hemostat of FIG. 1A are illustrated in FIGS. 2A through 2D, discussed below.  
         [0019]    In use in a preferred embodiment of the invention, one jaw of the hemostat of FIG. 1A is inserted into the interior right or left atrium through an incision provided in the wall of the left or right atrium, while the other jaw remains outside of that chamber. The jaws are pressed together, somewhat compressing the atrial wall between the jaws, to provide for continuous contact along the length of the jaws on both sides of the atrial wall. RF energy is delivered between the electrodes. Control of delivery of energy or power to assure a complete lesion may be accomplished by measurement of impedance between the electrodes, as in U.S. Pat. No. 6,133,592, issued to Taylor, U.S. Pat. No. 5,718,701, issued to Shai, et al or U.S. Pat. No. 5,357,956, issued to Nardella, or allowed Pending U.S. application Ser. No. 09/347,635, filed Jul. 6, 1999 by Hoey et al, all incorporated herein by reference in their entireties. Alternatively, thermocouples or other temperature sensors may be added to the jaws of the hemostat and delivery of energy or power controlled as in U.S. Pat. No. 5, 685,878, issued to Falwell, et al., U.S. Pat. No. 6,045,550, issued to Simpson, et al.,U.S. Pat. No. 5,688,267, issued to Panescu, et al or U.S. Pat. No. 5,596,995, issued to Sherman, et al., all also incorporated herein by reference in their entireties. As an additional alternative, delivery of energy or power may be time terminated, based upon empirically determined times found to lesions extending completely through the atrial walls at the power or energy levels chosen, or regulation of ablation energy by means of any of the references cited above may be employed if appropriate.  
         [0020]    It is anticipated that in some versions of the present invention which employ a more limited access approach to the heart, the distal tips of hemostat jaws themselves may be sharpened and used to pierce the atrial wall, eliminating the necessity of a separate incision. FIG. 1B illustrates such an alternative hemostat jaw construction, wherein hemostat jaws  18 A and  19 A correspond generally to jaws  18  and  19  in FIG. 1A, and carry electrodes  24 A and  25 A which also correspond to electrodes  24  and  25  in FIG. 1A. However, the distal tips  15  and  17  of the jaws are sharpened to a point or an edge so that either may be used to directly penetrate the atrial wall, eliminating the necessity of a separate incision.  
         [0021]    [0021]FIGS. 2A through 2D are cross sectional views through the jaws of a hemostats as in FIG. 1A, illustrating possible alternative constructions. In FIG. 2A, the jaws  18  and  19  are made of a metallic core  26 ,  28 , covered by an insulative coating or paint,  27 ,  29 . Electrodes  24  and  25  take the form of elongated conductive coils,  30 A,  33 A, carrying tubes  31 A,  32 A, of expanded PTFE, through which a conducted fluid such as saline solution may be delivered along the length of the electrode coils  30 A,  33 A. The lumens of the EPTFE tubes  31 A,  32 A may be sealed at their distal extremities.  
         [0022]    [0022]FIG. 2B illustrates a first alternative embodiment, corresponding generally to that illustrated in FIG. 2A, with elements corresponding to those identically numbered in in FIG. 2A. In this embodiment, the configuration of the conductive coil,  31 B,  32 B and the expanded PTFE tubes,  32 B,  33 B is reversed, so that the coils are located within the EPTFE tubes. As in the embodiment illustrated in Figure A, saline or other conductive fluid is delivered through the inner lumen of EPTFE tubes  32 B,  33 B.  
         [0023]    [0023]FIG. 2C illustrates a third embodiment according to the present invention. In this case, elements also correspond to identically numbered elements in FIG. 2A. However, in the embodiment of FIG. 2C, elongated guides or flanges  35  are added in order to enhance longitudinal alignment of the jaws  18  and  19 , along their length. When heart wall tissue is compressed between jaws  18  and  19 , flanges  35  tend to retain jaws  18  and  19  and correspondingly electrode coils  30 A and  33 A in alignment with one another, through the intermediary of the atrial wall tissue.  
         [0024]    [0024]FIG. 2D illustrates a fourth embodiment, corresponding generally to that illustrated in FIG. 2B, discussed above. Elements correspond to identically numbered elements in FIG. 2B. In addition, jaws  18  and  19  are each provided with elongated magnetic elements  37 , arranged to assist in pulling jaws  18  and  19  toward one another when the jaws are closed around atrial wall tissue. Elements  37  may be formed of rare earth magnets, so that their mutual attraction provides additional compressive force along the length of jaws  18  and  19 , enhancing contact with atrial wall tissue. In the case of embodiments in which the cross sectional size of jaws  18  and  19  is reduced in order to facilitate insertion into tight spaces, inclusion of magnets  37  is believed particularly valuable. The inclusion of magnets  37  is also believed particularly valuable in embodiments in which jaws  18  and  19  are fabricated of a less rigid material, for example a somewhat flexible plastic as opposed to a rigid metal such as stainless steel.  
         [0025]    It should be understood that the above-described cross sectional illustrations of the configurations of the jaws of the hemostat of FIG. 1A also apply to the construction of the jaws of the other three hemostats discussed below in conjunction with the present invention. The spacing between the electrodes on the jaws of these hemostats should also be understood to correspond to that of the hemostat of FIG. 1A. As such, electrode configurations for the hemostats of FIGS.  3 A- 5 B are not discussed separately herein. Similarly, while conductors and fluid lumens are not illustrated in FIGS.  3 A- 5 B, they should be understood to be present and correspond to those as illustrated in FIG. 1A. In addition, sharpened jaw tips as illustrated in FIG. 1B may also be employed.  
         [0026]    [0026]FIGS. 3A and 3B illustrate top and side views, respectively, of a second hemostat according to the present invention. In this case, the hemostat is provided with first and second handle portions  111  and  112 , which correspond to handles  11  and  12  of the hemostat illustrated in FIG. 1A, and is also likewise provided with a locking mechanism  114 . The jaws  118  and  119  correspond generally in structure to the jaws  18  and  19  of the hemostat of FIG. 1 , however, in this case, the jaws  118  and  119  are bent to describe a generally straight distal portion extending over a length E2, which may be, for example, 5½ centimeters. The jaws are bent at C2 around a radius of approximately 0.5 centimeters and describe an angle D2 of approximately 60 degrees, as illustrated. The overall length of the hemostat B2 may be, for example, 23 centimeters, with the overall length of the jaws as illustrated at A2 being, for example, about 6½ centimeters from pivot  116  to the distal ends of the hemostat jaws, as measured in the plane defined by the handle members  111  and  112 .  
         [0027]    [0027]FIGS. 4A and 4B similarly illustrate top and side views of a third hemostat according to the present invention. Like the previous hemostats, this hemostat is provided with handled portions  211  and  212  and a conventional locking mechanism  214 . Like the hemostat illustrated in FIGS. 3A and 3B, jaws  219  and  219  of this hemostat are similarly bent out of the plane defined by the two handled portions  211  and  212 . In this case, the jaws  218  and  219  are bent to define a distal, generally straight portion E3 extending for approximately 2 centimeters, and are bent around a radius C3 of approximately 3 centimeters, to define an angle D3 of approximately 65 degrees. The overall length of the hemostat as measured in the plane defined by the handles  211  and  212  is approximately 26 centimeters, and the length of A3 of the jaws, as measured along the plane defined by the handles  211  and  212  is approximately 6 centimeters.  
         [0028]    [0028]FIGS. 5A and 5B illustrate a fourth hemostat according to the present invention. Like the other hemostats, it is provided with handled portions  311  and  312  and a locking mechanism  314 . This hemostat also displays a curved configuration, with jaws  318  and  319  bent upward out of plane defined by the handled portions  311  and  312 , to define a generally straight distal portion extending over a length E4 of approximately 3 centimeters, and around a radius C4 of approximately 5 centimeters to define an angle D5 of approximately 60 degrees. As measured along the plane defined by handle  311  and  312 , the overall length B4 of the hemostat is approximately 29 centimeters and the length A4 of the jaws extending from hinge  316  to the distal tips of jaws is approximately 9 centimeters.  
         [0029]    FIGS.  6 A- 6 M are schematic drawings which illustrate a procedure performed using the bipolar electrosurgical hemostats described above to obtain a result analogous to the Maze III procedure as described in the Doty reference cited above. The lines of lesion produced using the hemostats correspond to incisions as described in this reference, and the correspondence of the lesions to the incisions is described below.  
         [0030]    [0030]FIG. 6A is a schematic drawing illustrating the structure of the right and left atria,  500 ,  502 , respectively, as viewed from a lower aspect, including tricuspid valve  16  and mitral valve  14  and as viewed from a more superior aspect, including the bases of the pulmonary veins  512 and the bases of the superior vena cava and inferior vena cava, 508  and  510  respectively, which enter the right atrium  500 . The right and left atrial appendages are also illustrated schematically at  504  and  506 , respectively. The structures as illustrated in FIG. 6A are correspondingly numbered in FIGS. 6B through 6M below.  
         [0031]    For purposes of understanding the basic method of the present invention as illustrated, it should be assumed that the operation is undertaken as an open chest operation, with the heart stopped and the patient on full bypass. Modifications to the procedure, in case of a limited access, stopped heart procedure and/or a limited access, beating heart procedure, are also generally described. FIG. 6B illustrates the first step of the procedure, comprising removal of the right atrial appendage  504 . Right atrial appendage  504  is removed by means of an incision  507 , which may be made by means of a scalpel or scissors. In a context of a closed chest procedure on either a beating or a stopped heart, a thoracoscopic tool may be substituted, preferably one capable of simultaneously cutting and stapling the remnant of the right atrial appendage.  
         [0032]    [0032]FIG. 6C illustrates the second step of the procedure, as performed using an open chest approach. During the second step, the electrosurgical hemostat of FIG. 1A is employed, with one jaw ( 19 ) of the hemostat inserted into the right atrium through the opening left by removal of the right atrial appendage and the other jaw arranged along the exterior surface of the heart. Jaws  18  and  19  are inserted until they extend to a point  520  located approximately at the mid point of the right atrium, approximately 5 centimeters from the opening  505  left by removal of the right atrial appendage. The jaws  18  and  19  are compressed and RF energy is applied between the electrodes located in jaws  18  and  19  to create an elongated lesion, extending through the tissue of the right atrial wall, to provide a block against passage of depolarization waves. For purposes of the following drawings, the placement of various hemostats will be described, but not specifically illustrated. Instead, the lesions to be produced by the hemostats will be illustrated by means of beaded lines, so that their interconnection and their relationship to the structures of the left and right atria  502 ,  500 , may be understood. It should be understood that the hemostats are to be placed with their jaws extending along the lines of lesion as illustrated, unless otherwise specified.  
         [0033]    In closed chest, limited access procedures, it is anticipated that the lesion produced may be made by inserting the jaw of an electrosurgical hemostat as illustrated in conjunction FIG. 1A, but having a sharpened tip as illustrated in FIG. 1B, directly through the heart wall at point  520 , and the jaws advanced to the sealed remnant of the removal of the right atrial appendage to define a corresponding lesion.  
         [0034]    [0034]FIG. 6D illustrates the next step in the procedure and also illustrates lesion  522  produced by the application of the electrosurgical hemostat as illustrated in FIG. 6C. Lesion  522  corresponds generally to the incision illustrated at step A 1  as described in the Doty reference. At  524 , a local access incision is cut, at a point approximately midway between the inferior vena cava and superior vena cava ( 510 ,  508 ). Lesions  526  and  528 , extending from access incision  524  to the superior and inferior vena cava, respectively, are produced by inserting one jaw of a hemostat as illustrated in FIG. 1A through the access incision  524  and arranging the jaws of the hemostat to extend on either side of atrial tissue from the incision  524  to the superior vena cava and inferior vena cava, respectively. Alternatively, a hemostat as illustrated in FIGS. 3A and 3B might be employed, with atrial tissue compressed between the straight, distal portions of the jaws. The lesions  528  and  526  so produced correspond to the incisions illustrated at step B as described in the Doty reference. In more limited access surgeries, hemostats having sharpened jaws as illustrated in FIG. 1B might be employed, with the sharpened tip of a jaw employed to create the access incision  524 .  
         [0035]    [0035]FIG. 6E illustrates the next step in the procedure. In this step, one jaw of a hemostat as illustrated in FIG. 1A or as illustrated in FIGS. 3A and 3B is inserted through access incision  524 , and the jaws are arranged along either side of the atrial wall to create lesion  530 , extending to the annulus of tricuspid valve  516 , terminating at a point  534  approximately at the center of the posterior leaflet  532 . This lesion should extend as close as possible to the tricuspid annulus. This lesion corresponds generally to the incision illustrated at steps D and E as described in the Doty reference. Optionally, cryo-ablation may be performed to complete the lesion at the tricuspid annulus at the terminus of lesion  530 , by means of a cryo-probe inserted through the opening  505  in the remnant of the right atrial appendage. Cryo-ablation corresponds generally to that illustrated at step F as described in the Doty reference. In more limited access surgeries, the cryo-probe might be inserted through access lesion  524  or might be inserted transvenously.  
         [0036]    [0036]FIG. 6F illustrates the next step of the procedure. In FIG. 6F, lesion  536  is created using the distal portion of the jaws of a hemostat as in FIG. 1A. One jaw of the hemostat is inserted through the opening  505  in the remnant of the right atrial appendage, and the jaws are arranged to extend along either the right atrial wall to the annulus of the tricuspid valve  516  at the midpoint of the anterior leaflet  538 . This lesion corresponds generally to the incision illustrated at steps H and I as described in the Doty reference. Care must be taken during this step to avoid the right coronary artery. Optionally, cryo-ablation may be applied at the tricuspid annulus at point  540 , at the termination of lesion  536 . Again, cryo-ablation may be provided by means of a cryo-probe inserted via the opening  505  in the remnant of the right atrial appendage, through access lesion  524 , or, alternatively be means of a cryo-probe inserted transvenously. Cryo-ablation corresponds generally to that illustrated at step J as described in the Doty reference.  
         [0037]    [0037]FIG. 6G illustrates the next step of the procedure which is the creation of an incision  542  extending through the left atrial wall, posterior to the inter atrial groove, near the orifices of the right pulmonary veins. In an open chest procedure, incision  542  may be made conventionally by means of scissors or a scalpel. Incision  542  corresponds to the incision illustrated at step K as described in the Doty reference. In more limited access surgeries, incision  542  might be replaced by a simple access incision made by means of the sharpened tip of one of the jaws of the hemostats used to create the lesions surrounding the orifices of the pulmonary veins, as discussed below.  
         [0038]    [0038]FIG. 6H illustrates the next step of the procedure, which is the creation of lesions  543  and  546 . Lesions  543  and  546  may be accomplished by insertion of a hemostat having curved jaws as illustrated in FIGS. 5A and 5B, reversing the orientation of the hemostat between lesions, to create lesions extending around the base of the pulmonary veins  512  and meeting at a point  544 , to complete the line of lesion. Incision  542  completes the line of lesion encircling the bases of the pulmonary veins. Lesions  543  and  546  correspond generally to the incisions illustrated at steps L and N as described in the Doty reference. In an alternative procedure, Lesions approximating the incisions illustrated at steps L and N may be produced by compressing the atrial wall tissue adjacent the bases of the left pulmonary veins between jaws of the hemostat illustrated in FIG. 4A or  5 A applied epicardially to produce a lesion encircling the bases of the left pulmonary veins and repeating the procedure to correspondingly produce a lesion encircling the bases of the right pulmonary veins.  
         [0039]    [0039]FIG. 6I illustrates the next step of the procedure, in which a hemostat having more sharply curved jaws, as illustrated in FIGS. 4A and 4B is employed to create lesion  548 . Lesion  548  is created by inserting the jaws of the hemostat illustrated in FIGS. 4A and 4B, one into incision  542 , the other into access incision  524 , and compressing the atrial septum therebetween. The jaws are arranged so that they define a curved lesion extending along the atrial septum, extending to a point above the fossa ovalis, near but not into the tendon of Todaro. As the atrial septum is not visible in FIG. 6J, lesion  544  should be understood to correspond to the incision illustrated at step M as described in the Doty reference.  
         [0040]    [0040]FIG. 6J illustrates the next step in the procedure, comprising the removal of left atrial appendage  506  by means of an incision  550 . In open chest procedures, this incision might be made by means of a scissors or scalpel. In more limited access surgeries, this incision might be made by means of a thoracoscopically introduced, preferably one capable of simultaneously cutting and stapling the remnant of the right atrial appendage.  
         [0041]    [0041]FIG. 6K illustrates the next step of the procedure, comprising the creation of lesion  552 . Lesion  552  may be created using the curved hemostat illustrated at FIGS. 5A and  5 B to create a curved lesion departing from lesion  546  and extending to the opening  550  in the right atrial appendage. As with lesions  543  and  546 , the lesion may be produced by inserting one jaw of the hemostat through the incision  542 , and compressing the left atrial wall between the jaws of the hemostat. Lesion  552  might also be performed prior to removal of the left atrial appendage, in conjunction with creation of lesions  543  and  546 . In some embodiments of the invention, lesion  542  might be replaced by a simple incision extending from the opening  550  of the remnant of the left atrial appendage, and then later repaired by sutures.  
         [0042]    [0042]FIG. 6L illustrates the next step of the procedure, comprising the creation of lesion  558 . Lesion  558  is created using the curved hemostat of FIGS. 5A and 5B, one jaw being inserted through incision  542  and compressing the left atrial wall between the jaws of the hemostat to create a lesion extending from lesion  543  to the mid point  560  of the annulus of the posterior mitral valve. Lesion  558  corresponds to the incision illustrated at step S as described in the Doty reference. Care must be exercised during this incision to prevent damage to the circumflex artery and the coronary sinus. Optionally cryo-ablation may be provided at the mid-point  560  of the posterior mitral valve annulus, by means of a cyro-probe introduced through the opening  550  through the remnant of a left atrial appendage, or through incision  542 . In more limited access surgeries, cryo ablation may be provided by means of transvenous cyro-ablation catheter. Cryo-ablation corresponds generally to that illustrated at step J as described in the Doty reference.  
         [0043]    [0043]FIG. 6M illustrates the final steps of the procedure, comprising closing of the openings  505  and  550  into the remnants of the right and left atrial appendages, respectively, by means of sutures  554  and  556 . As noted above, in the event that thoracoscopic surgical implements are employed, these openings may have previously been closed in conjunction with their creation, by means of staples, or otherwise, by means of thoracoscopic surgical tools. In addition, incision  542  is shown as closed by means of sutures  560  as discussed above, in some embodiments, incision  542  may have been replaced by simple puncture incision, which might be closed by means of staple, sutures, or otherwise, applied thoracoscopically. Access in incision  524  is similarly closed at this time.  
         [0044]    The hemostats as illustrated in FIGS. 1A through 5B, discussed above, have the general configuration of conventional hemostats, as would be employed in the context of an open chest procedure. In the event that the procedure is adapted to a thoracoscopic procedure, similarly configured hemostat jaws may be employed on thoracoscopically introduced instruments to create the various lesion patterns. It is also envisioned that some modifications to the specific configurations of the disclosed hemostats may be desirable in conjunction with adapting the hemostats to thoracoscopic use or, in conjunction with adapting the hemostat set to other versions of the Maze or Maze type procedures. Such modifications are believed to be within the scope of the invention.  
         [0045]    While all of the hemostats disclosed in the present application are preferably provided with R-F electrodes to create elongated lesions, it is believed the invention may also usefully be practiced in conjunction with hemostats employing microwave, heat, cyroablation, laser or other ablative techniques to create the various lesions provided by the method. Further, while the hemostats disclosed in the present application are provided with a single elongated electrode extending along each jaw, embodiments in which multiple electrodes arrayed along each jaw are employed are also believed useful in practicing the invention in some cases.  
         [0046]    Therefore, the above disclosure should be considered as exemplary, rather than limiting, with regard to the following claims.