Abstract:
A ring-handled bypass clamp provide a spoon-shaped blade insertable through a temporary incision in the ascending aorta and a cooperating ring positionable on the exterior of the aorta opposite to the blade. An aortotomy is performed on the portion of the aorta wall inside the ring to provide an annular portion of the wall to which a graft is sutured.

Description:
BRIEF SUMMARY OF THE INVENTION 
     This invention relates generally to surgical instruments, and more particularly to a surgical clamp and a surgical procedure in which the clamp is used in carrying out an aortocoronary bypass. 
     Bypass operations provide an alternate conduit for blood to flow, around occluded segments of arteries or veins. The most common of these is a lateral anastomosis for the treatment of coronary artery diseases caused by atherosclerosis or narrowing of the small arteries between the aorta and the heart muscles. A section of saphenous vein, or a suitable substitute, is grafted, usually between the ascending aorta just above the heart and one or more of the coronary arteries beyond the points of blockage. As many as six grafts may be carried out in an individual patient depending on the circumstances. The operation is performed with the patient connected to a heart-lung machine and the heart stopped. A conventional side-biting aortic clamp pinches a folded side of the ascending aorta wall near the heart to form an occluded site for an aortotomy in order to prevent loss of blood. 
     The side-biting aortic clamp, however, has shortcomings. In some cases, for example, it adds further risks where atheromatous plaque has accumulated in a patient&#39;s ascending aorta. When the heart-lung machine and clamp are removed and natural circulation is restored, this plaque may dislodge and be carried through the carotid arteries to the brain, where it can cause serious cerebral damage. Furthermore, cutting only one folded section of the pinched wall and suturing a graft to it for a lateral anastomosis can be difficult and time consuming. This is due, in part, to the fact that the aorta is only about 25 mm in diameter, and the pinched wall section formed by the bite of the side-biting clamp is only a relatively small portion of the aorta. Still another problem with the conventional side-biting clamp is that, unless great care is taken in carrying out the aortotomy, there is a possibility of damaging other portions of the aorta wall. It is therefore apparent that there is a need for a surgical clamp which will reduce the risk of dislodging life-threatening atheromatous plaque, and provide a site readily accessible for aortotomy and suturing for a lateral anastomosis. 
     Accordingly, one object of this invention is to provide an improved bypass clamp suitable for use in grafting a lateral anastomosis to a blood vessel in a patient. 
     Another object is to provide a clamp which will hold an occluded portion of the ascending aorta wall in a readily accessible position for grafting a lateral anastomosis thereto in a coronary bypass operation. 
     Still another object is to provide a coronary bypass clamp which can be applied with reduced risk of dislodging life-threatening atheromatous plaque accumulated in the ascending aorta of a patient. 
     A further object is to provide a coronary bypass clamp which provides a site in the ascending aorta suitable for performing an aortotomy and for attaching a lateral anastomosis with a minimum loss of blood. 
     A still further object is to provide an improved method for performing a lateral anastomosis. 
     Briefly, these and other objects of the invention are achieved with a bypass clamp having a pair of handles pivoted together in the middle, each having a connected finger grip on one end and a ring and a bowl-shaped blade, respectively, on opposed distal ends for sealingly clamping opposite sides of the wall of a blood vessel. As applied in a lateral anastomosis of a blocked blood vessel, the blade is inserted through a temporary incision in the vessel and positioned, above a blockage, at a selected site for attaching a graft. The clamp is then closed, causing the ring to secure the wall of the vessel over the blade and form a continuous annular seal between the wall and the rim of the blade. A generally circular aortotomy is then made in the wall within the ring leaving a portion of the wall around the opening sufficient for suturing one end of a graft. The blade- wall seal prevents blood from escaping through the opening during this process. The distal ends of the clamp are then opened to draw the free end of the graft through the ring after which the blade can be withdrawn through the temporary incision. The anastomosis may now be completed by suturing the free end of the graft at a point communicating with the vessel beyond the blockage, and permanently closing the temporary incision. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, novel features and advantages of the invention will become more apparent from the following detailed description when considered in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an isometric view of one embodiment of a clamp constructed according to the invention suitable for use in coronary bypass surgery; 
     FIG. 2 is an elevational view of the clamp of FIG. 1; 
     FIG. 3 is an anterior view of an ascending aorta with a blade and ring at distal ends of the clamp of FIG. 1 positioned at a site selected for an aortotomy; 
     FIG. 4 is a fragmentary perspective view showing the blade and ring of FIG. 3 after being secured to the wall of the aorta around the aortotomy; 
     FIG. 5 is a cross-sectional view of the blade and ring taken on plane 5--5 of FIG. 4, with a graft end sutured to the aorta; 
     FIGS. 6a and 6b are fragmentary plan and cross-sectional views respectively of another blade and ring configuration for a clamp according to the invention; and 
     FIGS. 7a and 7b are fragmentary plan and cross-sectional views of still another configuration of a blade and ring according to the invention. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings wherein like characters designate like or corresponding parts throughout the several views, FIG. 1 shows a clamp suitable for use in coronary bypass surgery comprising a pair of elongate handles 12 and 14 of steel, such as Type 410X martinsitic stainless steel, pivotally connected on an axis intermediate opposite ends thereof by a substantially stress-free hinge integrally formed in a box lock-joint 16 such as disclosed in U.S. Pat. No. 3,952,749 to John Fridolph et al. Handles 12 and 14 are defined by substantially straight arms 12a and 14a, extending from joint 16 and terminating with ring-shaped finger grips 18 and 19 for opening and closing the instrument by a scissors-like manipulation; and by curved arms 12b and 14b, extending from joint 16 in the same plane of motion as arms 12a and 14a, and terminating with a blade 20 and ring 22, respectively. As more clearly shown in FIG. 2, arms 12b and 14b gradually diverge in the same direction from the respective longitudinal axes of arms 12a and 14a near lock-joint 16. 
     Blade 20 defines a generally circular bowl 20a with a rim 20b situated in a plane parallel to the facing side of ring 22 when clamp 10 is closed in a normal clamping position. The circumference of rim 20b and ring 22 are congruent, thus assuring a relatively uniform clamping pressure to opposed sides of the aortic wall. Various other configurations of the distal end of the clamp 10 are contemplated depending on circumstances such as the location and size of the blood vessel, nature of the anastomosis, and surgeons&#39; preferences. Two other examples are illustrated in the drawings. FIGS. 6a and 6b show a spoon-shaped blade 60 with a generally circular bowl 60a and a raised rim 60b. The perimeter of a rim 60b around the bowl is congruent with an annular groove 62a in the facing side of a ring 60. FIGS. 7a and 7b show another spoon-shaped blade 70 with an oval-shaped, generally elliptical, bowl 70a and a raised rim 70b around the recess which is congruent with a continuous groove 72a around the facing side of a ring 72. 
     As shown in FIG. 1, lugs 24 and 26, adjacent to grips 18 and 20, project laterally toward each other from arms 12a and 14a to form a ratchet for locking clamp 10 in the closed position when blade 20 and ring 22 are manually squeezed together. The stiffness of the handles and the locking position of lugs 24 and 26 determine the clamping force. 
     By way of illustration but not of limitation, a typical clamp as described above, suitable for aortocoronary bypass surgery is constructed with an overall length of 16 cm, including blade 20 and ring 22 which are each 15 mm long. The blade width and depth are 8 or 11 mm and 6 mm, respectively. Curved arms 12b and 14b each have a radius of curvature of 2.0 cm and cord length of 1.9 cm. The dimensions, of course, are approximate and will vary according to requirements and personal preferences of the surgeon. 
     The manner in which clamp 10 is utilized in a aortocoronary bypass surgical procedure is illustrated in FIGS. 3-5. Referring first to FIG. 3, the ascending aorta A is totally occluded proximal to the innominate artery B by jaws 30 of a cross-clamp to prevent backflow of blood from a heart-lung machine (not shown) which is connected beyond the cross-clamp. A temporary incision M is made in the ascending aorta A, at a location near the heart H, for insertion of blade 20 of clamp 10 so that it can be moved toward the site selected for an aortotomy. Patches P of saphenous vein or suitable substitute may be sutured on either side of the incision as reinforcement of the aorta to prevent tearing or abrasion by clamp 10. 
     As shown in FIGS. 4 and 5, when the blade is brought to the site selected for the aortotomy, clamp 10 is closed and locked by lugs 24 and 26. This causes ring 22 to form a continuous seal of the aorta wall to rim 21 of blade 20. Being totally isolated from the interior of the aorta by the plate-wall seal, a circular aortotomy N, less than the diameter of ring 22, is made with little or no loss of blood in the exposed wall within ring 22. The annular portion of the wall around the opening and within the ring is left for suturing one end of a graft G thereto. 
     The anastomosis is completed by opening clamp 10 and pulling the free end of graft G through ring 22 so that blade 20 can be withdrawn through incision M. The free end of graft G is then attached to the coronary artery beyond the blockage, the temporary incision closed, and the heart-lung machine disconnected upon restoration of heart function. 
     Some of the many advantages and novel features of the invention should now be readily apparent. For example, a bypass clamp is provided which is particularly suitable for grafting a lateral anastomosis to a blood vessel in a patient. It provides a readily accessible area around an opening in a blood vessel for suturing the graft. In a coronary bypass procedure, it reduces the risk of dislodging life-threatening atheromatous plaque accumulated in the ascending aorta of a patient, and it offers a significantly improved method for performing bypass surgery with minimal loss of blood. 
     It will be understood, of course, that various changes in the details, steps and arrangement of parts can be made. For example, while the preferred embodiments specifically disclosed are in the form of ring-handled instruments having a pivot joint, it is possible to realize many of the advantages of the invention in a version in which the ring and blade are interconnected by another form of linkage, for example a linkage utilizing a screw to effect movement of the blade and ring toward and away from each other. Still other modifications may be made by those skilled in the art within the principal and scope of the invention as expressed in the appended claims.