Surgical Principles in the Direct Reconstruction of Left Coronary Flow

Transcription

1 Surgical Principles in the Direct Reconstruction of Left Coronary Flow W. Dudley Johnson, M.D., Robert J. Flemma, M.D., Harold W. Harding, M.D., George N. Cooper, Jr., M.D., and Dcrwarcl Lcplcy, Jr., M.D. D irect coronary surgery in Milwaukee.began in October, Two segmental obstructions in the proximal right coronary artery were treated with the patch graft technique as described by Crafoord [ll and subsequently by Effler [Z]. In both instances, and in most cases since that time, nonobstructing atherosclerosis was found to extend well above and below the stenotic area. Rather than suturing into diseased artery, it seemed logical to expose a normal portion of the artery distally, make a simple arteriotomy, and suture a tapered vein graft to the side of the coronary artery in a manner similar to that used for a patch graft. The other end of the vein would be attached to the aorta. The concept of the end-to-side anastomosis to a normal segment of a distal coronary artery thus evolved. The use of vein graft interposition in proximal right coronary reconstruction was first reported at that time [3], lending further support to the use of veins as coronary substitutes. However, our concept of the end-to-side distal anastomosis differed considerably from the interposition procedure. The procedure now utilized has been the same, with only minor variation, since we originated our endeavors in direct coronary surgery. Venous-coronary anastomoses to small distal right coronary branches were so consistently successful that the methods were first applied to the left coronary system beginning in September, With the improved techniques, it has been possible to carry out one or more vein bypass grafts in 97% of patients undergoing myocardial revascularization. Many of the principles of this surgical technique, including the types of patients operated upon, have been presented elsewhere [4-61. It is the purpose of this report to present in detail the operative techniques that first made approach to the left coronary system practical. From the Department of Thoracic-Cardiovascular Surgery, Division of Surgery, Marquette School of Medicine, Milwaukee, Wis. Presentcd at thc Sixth Annual Meeting of The Society of Thoracic Surgeons, Atlanta, Ga., Jan , Address reprint requests to Dr. Johnson, 8700 West Wisconsin Ave., Milwaukee, Wis VOL.. 10, NO. 2, AIIGIJST,

2 JOHNSON ET AL. GENERAL SURGICAL PRINCIPLES A coronary incision has been developed and used for two and one-half years (Fig. 1). The sternum is split, but the linea alba is not disturbed. Instead, the incision extends to the left paramedian area, dividing the anterior rectu, sheath longitudinally for several inches. At the level of the xiplioid, the posterior left rectus sheath is cut transversely. These two incisions markedly relax the anterior left chest. As a Morse sternal spreader is inserted, the left chevt moves up and laterally, greatly facilitating exposure of the left ventricle and coronary system. Having the left chest so exposed and elevated facilitates dissection of the mammary artery. Rake-type retractors have not ken needed. An inverted T incision is made in the pericardium, leaving a cuff of pericardium 2 to 4 cm. wide attached to the diaphragm. The inferior flap of the pericardium is rolled downward and permanently sutured to the transverse rectus sheath. This maneuver pulls the inferior pericardium down and away from the heart and elevates the heart slightly, both of which facilitate exposure of the distal right coronary system. Epigastric and substernal hernias are avoided because the posterior rectus sheath is intact and the pericardium is firmly connected to the rectus sheath. All patients undergoing coronary operations are placed on full cardiopulmonary bypass. We prefer moderate hypothennia at 3OOC. Arterial return is made into the aortic arch through a 12-mm. woven graft sutured end to side to the aorta. Although slightly more time consuming, this technique avoids the hazards of perfusing through femoral or iliac arteries which are commonly diseased. A 3- to 4-mm. stump of graft is left after perfusion, and this is closed FIG. 1. Exposure of the left uentricle and the left coronary system is facilitated by relaxing the left anterior chest. The anterior rectus sheath is cut longitudinally and the posterior sheath transuersely at the xiphoid level. When a simple sternal spreader is inserted, the left chest moues much farther laterally and upward than with the standard sternal-linea alba incision. Rake-type retractors are not needed. 142 THE ANNALS OF THORACIC SURGERY

3 Direct Reconstruction of Left Coronary Flow with a simple running suture. No instance of major complication has resulted from this method of arterial return. The left ventricle is vented through tlie apex or the left atrial appendage. Tlie latter is preferred if there are many collateral arteries over the apical surface. The heart is then electrically fibrillated. At 30 C. myocardial fasciculations are very fine in contrast to those at normothermia, allowing for more careful suturing of the coronary arteries. When the heart is first exposed, several observations should be made: size, contractility in all areas, extent of epicardial scar, amount of distal coronary filling, and extent of atherosclerosis. One or two traction sutures, reinforced with a Teflon felt pad, are placed in a bare area of the myocardium on tlie lateral or posterior surface of the ventricle. Traction on these sutures exposes the lateral and posterior heart without difficulty. A pad placed behind the heart for elevation also facilitates exposure of the anterior coronary system. ldentification of the coronary arteries and dissection and exposure of the vessels are then performed. One major and one minor anatomical clue have allowed us to expose tlie anterior descending artery without fail. The first, and most important, is that the anterior artery nearly always lies directly beneath the most prominent longitudinal furrow or groove in the epicardial fat. Even when tlie anterior heart is covered with 1 cm. or more of fat, a prominent and conspicuous groove or dimpling in this fat directly overlies the anterior descending artery (Fig. 2). Tlie second landmark is the vein draining the anterior surface of tlie ventricle, as this usually lies 3 to 4 mm. to the left of the anterior descending artery. When the artery cannot be identified, the dissection should be initiated to the right of this major vein. It is not unusual for the proximal anterior artery to be buried within the myocardium, making gross palpation or observation of the artery impossible on superficial examination. Even in this situation, the distal portions of the anterior artery emerge and course over the epicardial surface. The artery can be exposed distally and the dissection carried proximally. When the artery goes beneath the myocardium, the myocardium overlying the artery is simply cut and the fibers retract laterally, thus exposing the artery. On no occasion has the overlying muscle been more than 1 or 2 mm. thick. When it is necessary to expose a more proximal portion of the anterior artery from beneath tlie muscle, the myocardium is split directly beneath the major groove. The FIG. 2. Anterior descending coronary nrfrry exposed by dissecting into major groovr. Vessel is collapsed and white. VOL. 10, NO. P, AUGUST,

4 JOHNSON ET AL. midportion of the artery, below the diagonal branch, i5 tlic ;u ea iriost coinmoiily used for the anastomosis. This is the easiest area to expose. With the end-to-side technique, adequate flow is achieved in both directions (Fig. 3). The exposure of the circumflex artery is somewhat more difficult. It the block is at the origin of the circumflex artery and the distal portion is relatively normal, the artery can be exposed in the atrioventricular groove. The artery runs high in the groove, and a large coronary vein usually lies anterior and inferiorly to the circumflex artery. To expose this artery, the heart must be collapsed and then retracted to the right side with the aid of two large traction sutures placed in the myocardium (Fig. 4). The left atrial appendage is gently elevated and pulled superiorly. The dissection should proceed immediately adjacent to the left atrial appendage while reflecting the coronary vein downward. As the dissection proceeds along the surface of the atrial appendage, the circumflex artery will be exposed. More commonly, in our experience, a major obstruction extends out into the circumflex more distally and involves the origin of ;i large marginal branch. To expose the marginal artery, the heart is siniilarly retracted to the right side and the artery is dissected free in the upper third on the lateral surface. The major marginal branch of the circumflex artery is also frequently buried beneath the myocardium. A superficial vein is often visualized on the surface very close to the position of the marginal artery. At times the artery can be seen as a red streak just below a thin layer of muscle. Poorly filled or nonfilled arteries are often collapsed and small. Slight manipulation or dissection often produces severe coronary spasm. As soon as the arteries FZG. 3. Postoperative cineangiogram demonstratii7g bidirectional flow after endto-side anastomosis. Contrast medium flows back to main left coronary artery (LC) as well as distally (arrows). 144 THE ANNALS OF THOI<ACIC SURGERY

5 FIG. 4. Exposure of the circumflex artesy is made by collapsing the heart arid retracting it to the right side. Two OY three traction sutures, reinforced with Teflon felt, facilitate exposure of the circumpex branches. CVG = circumflex vein graft; PA = pulmonary artery; LA = left atrial appendage. have been dissected free and exposed, a dilute papaverine solution is sprayed onto the artery. Within minutes, the arteries often dilate considerably and the true arterial size can be more easily determined. In all instances only the upper surface of the artery is exposed. The intima of coronary arteries is soft, often thick, and is easily damaged. Tapes, clamps, and traction sutures are never placed about a recipient artery. Saphenous veins are used for the vein bypass procedure. The vein is reversed in its direction and no attempt is made to remove the valves. For the coronary cnd, the vein is cut obliquely and the tip is carefully rounded. All side branches of the vein are suture-ligated flush with the vein. The vein-to-coronary artery anastomosis is performed first. After the area for the anastomosis has been selected on the coronary artery, this artery is opened. In general, the vein is inserted beyond the last area of atherosclerosis, even if this means using the distal third of the anterior descending artery. More than 90% of the arteries have an internal diameter under 3 mm. It is very hazardous to open this type of artery with ;I knife blade. A 6-0 suture is passed through the anterior surface of the artery and uently pulled upward. Using fine scissors, a tiny ellipse is removed from the anteror wall of the artery, thus exposing the arterial lumen. Once opened, the arteriotomy is extended in both directions. Probe patency of the recipient artery is tested using dilators from 1.5 to 3 mm. Forceful stretching of the artery must be avoided, as the coronary intima splits easily. Some back-bleeding from the open coronary artery invariably occurs. To achieve a dry field, the aorta is crossclamped. Finger compression of the aorta below the clamp expresses the residual blood through the coronaries and creates a completely dry field. The vein is VOL. 10, NO. 2, AUGUST,

6 JOHNSON ET AL. tapered to a length appropriate for the arteriotomy. Simple 6-0 sutures arc placed through each end of the vein grakt and of the arteriotomy. Once the two end sutures are in position, a running suture proceeding from each end and meeting in the middle on both sides i, placed. Patency of both ends of the anastomosis is tested with the probes (Fig. 5). Anoxic arrest is maintained for 15-minute periods with 5 minutes of coronary perfusion between periods of anoxia. The maximum time for which these ischemic hearts will tolerate total anoxia is not known, but 15 minutes has been endured consistently without difficulty. Distal perfusion has not been utilized while the anastomosis is being made. After the vein-coronary artery anastomosis is complete, arterialized blood in a syringe is pumped by hand into the vein graft. Any anastomotic leaks are sutured while the heart is still quiet. In addition, distal coronary perfusion is achieved. A small vascular clainp is then placed in the midportion of the vein to prevent back-bleeding while the vein is sutured to the aorta. All left-sided vein grafts are arched superiorly over the pulmonary artery and back down to the ascending aorta. They are attached into the anterior surface of the ascending aorta several centimeters above tlie aortic annulus. This large inverted U has several advantages. The most prominent area on tlie heart is the infundibulum and proximal pulmonary artery. This area is usually considerably anterior to the aorta. Veins passing directly from tlie anterior descending artery to the aorta angle acutely downward, and anastomosis into the aorta is difficult. When the veins curve superiorly around the pulmonary artery, they lie flat on the aorta and an end-to-side anastomosis is relatively easy. This high location removes tlie vein from the most prominent area and, theoretically at least, reduces the chances of its being compressed between the heart and the anterior chest wall. Should the patient need a subsequent operation, it also reduces the possibility of damaging the vein while opening the chest. In the collapsed heart, the distance from the coronary artery to the aorta is often very difficult to estimate. When the veins are made generously long, the additional length simply forms a larger arch which lies 1 or 2 in. out over the pulmonary artery. T~US it is almost impossible to make a vein too long for an anterior or circumflex graft. Double vein bypass graf t, to the anterior descending and circumflex arteries are frequently required. The second vein is attached to the side of the first vein. This requires much less vein than is needed with a double aortic origin. A single FIG. 5. Prior to conzplelioia of continzio2is-sut211-e anastotiiosis, a probe is passed distaliy and proximally to demonstrate pntency of end-to-side anastomosis. 146 THE ANNALS OF THORACIC SUKGEKY

7 Dii rrt Rpconsti urtion of Lpft Coi onary Flow aortic origin with the Y configuration tor right and left vein grafts is used only if the aorta is thin and friab!e or the ascending aorta is too short (cf. Fig. 7). Angiograms performed up to a year postoperatively have shown the Y anastomosis to be very satisfactory. On four occasions one side branch has occluded, but in no instance has the thrombus progressed and occluded both branches. When left-sided veins are attached to the aorta, thc tip 01 the vein angles inleriorly toward the aortic annulus. A partial occluding clamp is placed on the aorta and a simple slit is made. No portion of the aortic wall should be removed. The vein is prepared differently for the aortic anastomosis than it is for the coronary anastomosis (Fig. 6). For the aortic end, the vein is cut straight transversely. A single slit is made longitudinally on the back wall of the vein, forming a V. A single suture is placed at the tip of the V on the back wall of the vein (Fig. 6, A) and is attached to one end of the aortic incision. No attempt is made to taper or trim away the two flaps of vein formed when the vertical cut was made down the back wall. The midpoint on the end of the vein (Fig. 6, B) is sutured to the other end of the aortotomy. After these two sutures are tied, the anastomosis is completed by running a continuous suture beginning at the top of the V incision in the vein. A small needle is inserted into the vein just proximal to the occluding vascular clamp to release any air in the proximal graft. The clamp is then released, allowing flow to proceed into the coronary artery. When prepared and sutured in this manner, the vein forms a smooth cylinder as it arises from the aorta. When two veins are to be inserted, the first is inserted into the artery most in need of a new blood supply. This allows for immediate improvement in flow to that portion of the coronary system. The second graft is then attached to the other coronary artery or to the aorta (Fig. 7). The site selected for the vein-coronary anastomosis is highly variable. In general, we prefer to bypass all atherosclerotic segments and insert the vein into a normal portion of the distal artery. On occasion, diffuse atherosclerosis involves the entire length of the anterior descending artery, and diseased artery must be used. Most operative failures have occurred with this type of artery. Rarely is an endarterectomy performed. FIG. 6. Vein graft ready for aortic insertion. Simple sutures at A and B are connected to the ends of a straight incision in the aorta. No aortic tissue is removed. The two sutures are tied in place, and a continuous suture, beginning at point A and running to point R, completes the anabtomosis.

8 JOHNSON ET AI,. FIG. 7. Angiogram of double graft to anterior descending (AD) and right coronary arteries at one-year follozu-up. W e prefer to insert both veins separately into the aorta as in this case. If the aorta is thin or atherosclerotic, the anterior groft is attached to the side of the right vein gl-aft (VG). A second area of atherosclerosis distal to the primary obstruction is very commonly observed, especially in the anterior descending artery. The arteriotomy should be made across this secondary lesion to normal artery above and below the plaque. The vein is tapered across the full length of the arteriotomy and acts as a large patch <graft to eliminate any effect this secondary lesion may have on coronary flow. Bidirectional flow is preserved, which would not be so if the vein were placed just above or below the secondary lesion. Main left coronary artery disease is handled by creation of aortic vein-coronary artery bypass to the anterior descending coronary artery with the end-to-side anastomosis, allowing bidirectional flow back up to the main left block and into the circumflex distribution (Fig. 8). If there is severe obstruction extending from the main left coronary artery into both the anterior descending and the circumflex artery, they both should have vein bypass grafts to relieve obstruction. Thus the entire left coronary system may be perfused by a single bypass graft into the anterior descencling artery, or two bypasses may be required. Patients with main left coronary artery disease are treated as semiemergency cases and are operated upon within a few days after angiography. In patients with previous infarcts and poor function of the anterior wall, moderate to extensive scar tissue is often seen at operation. It is frequently difficult to determine by external examination if functioning muscle is present. When there is doubt, the area in question is probed with a needle. Dense fibrosis or scar tissue can easily be distinguished from soft muscle. When fibrotic tissue is extensive, a small ventriculotomy incision is made. The badly scarred area is then resected or plicated. Blind plication of scarred myocardium is not done, as mural thrombus is often present. One or more vein bypass *grafts are then inserted into the appropriate arteries. 148 TIIE ANNA1.S OF TIIORACIC SIJRGERY

9 Diwrt Rrcon\lritt tion of Left Coronary Flow FIG. 8. Angiogram performed 15 months postoperatively showing vein graft filling the entire left coronary artery system via a vein bypass to the anterior descending artery. The midportion of the anterior descending artery is most commonly the site of anterior descending artery disease also. No aneurysm or stenosis is seen at 15 monthy. C = circiimpm artery; AD = proximal antmior rl r \ cr ndi n g art e ry. COMMENT With the techniques described here, direct reconstruction of coronary flow to one or more arteries has been achieved in more than 97% of patients undergoing myocardial revascularization in A total of 207 left coronary vein grafts have been placed in 181 patients (Table). These patients are selected only in that they have had clinical coronary disease and angiographic confirmation of significant coronary atherosclerosis. Moderate to severe left ventricular malfunction (cardiac index below 2.4, end-diastolic pressure 12-53, abnormal ventriculogram in one or more areas), present in over 50% of these patients, has not contraindicated operation. Mortality has correlated more closely with ventricular function than with the type of operative procedure performed. In 36% of these patients, multiple arterial implants have been performed simultaneously using the technique of multiple implantation previously described [5]. The implants are now done only in patients with areas of demand not relieved with the vein bypass grafts. If, for example, in a patient with triple artery disease only one vein graft could be inserted, arterial implants into the other areas would be made. Patients rarely have single artery disease. Double and triple VOL. 10, NO. 2, AlJC.IlST,

10 JOHNSON ET AL. RESULTS OF SINGLE, DOUBLE, AND TRIPLE SAPHENOUS 1 EIN BYPASS GRAFTS IN 181 PATIENTS ( ) Procedure No. of Patients Hospital Deaths Single LAD 59 5 ( 8%) Circumflex 7 1(14%) Double LAD + right LAD + circumflex Circumflex + right Triple LAD + circumflex + right (15%) 2 (15%) 2 (40%) 14 G (40%) Total (15%) A total of 207 grafts were inserted. LAD = left anterior descending coronary artery; circumflex = circumflex artery; right = right coronary artery. vein grafts are now performed in more than 60% of patients [4]. Reconstruction of flow to the left coronary system alone is not adequate if there is extensive right coronary disease. Angiographic studies have been made from 2 weeks to 14 months in more than 75% of the patients. With nearly 300 veins visualized angiographically, the patency rate continues to exceed 90% and is highest for anterior descending artery grafts (95%). Using the methods of suturing described, there has been a low rate of stenosis at the anastomotic site (one case only) as seen angiographically. There have been two known late vein closures in the entire series. The clinical and physiological improvement in these patients has been discussed elsewhere [4-61. There have been three late deaths, all from noncardiac causes, in this series, and only one late infarct. We have had no experience with the internal mammary artery, coronary graft, or vein interposition operations. SUMMARY A technically satisfactory method has been developed for direct reconstruction of flow to all major branches of the left coronary system, often in combination with right coronary reconstruction. In 1969, 97% of patients undergoing myocardial revascularization had direct reconstruction of flow to one or more areas. No patients have been refused operation because of the extent of their coronary disease nor because of their degree of ventricular failure. The total mortality has been 15%, with a much lower rate for those with good ventricular function (7%). The late results continue to show satisfactory vein graft function and 150 THE ANNALS OF THORACIC SURGERY

11 Direct Reconstruction of Left Coronary Flow continued clinical improvenient. Whereas distinct improvement of the failing ventricle is commonly seen, the mortality in this group is higher. Continuing studies will be needed to determine the final role of vein bypass grafts for the coronary patient. K EFER EN C ES 1. Crnfoord, C. Some aspects 01 surgery for coronary disease. Slijgc')y 49:215, Effler, D. B., Sones, F. M., Jr., Favaloro, R. G., and Groves, L. K. Coronary endarterotomy with patch-graft reconstruction: Clinical experience with 31 cases. Ann. Szirg. 162:590, Favaloro, K. G. Saphenous vein autograft replacement of severe segment,tl coronary artery occlusion: Operative techniques. A?zn. Tholac. szii g. 5: 334, Johnson, W. D., Flemma, R. J., and Lepley, D., Jr. Direct coronary surgery utilizing multiple-vein bypass grafts. Ann. Tho? ac. Surg. 9:436, Johnson, W. D., Flemma, R. J., Lepley, D., and Ellison, E. Extended treatment of severe coronary artery disease: A total surgical approach. Ann. Stilg. 170:460, Johnson, W. D., and Lepley, D. An aggressive surgical approach to coronary disease. J. Thoiac. Cal-tlzova.x. Szirg. 59: 128, DISCUSSION DR. BEN MITCHEL (Dallas, Tex.): One year ago at the Society meeting in San Diego, Dr. Johnson was kind enough to discuss with us his experience with and techniques of vein bypass grafts to the left coronary artery. Prior to that time we had performed a few bypass grafts to the proximal right coronary artery, but Dr. Johnson convinced us that it is technically possible to implant a bypass graft to the left side, as well as to the distal right. To date, we have performed saphenous vein bypass grafts in 96 patients. Of 42 patients wlio have had single bypass grafts, in 13 the graft was taken to the right coronary artery, in 28 to the anterior descending artery, and in 1 patient to the circumflex artery. Thirty-nine patients have had double bypass grafts. The anterior descending and circumflex arteries were bypassed in 11 patients, the right coronary and anterior descending arteries in 27, and the right coronary and circumflex arteries in 1 patient. In 15 patients all three vessels were bypassed. Our surgical approach with these patients has been almost exactly like that outlined by Dr. Johnson today. There is one area of difference, however. Of the first 21 patients, roughly one-third received a posterior myocardial implant. In the subsequent 75 patients, no implants have been done, but roughly one-third, or 27 patients, have had a jump into the circumflex distribution. Personally, I now wonder whether implants are indicated in such cases. The mortality rate has been 11%. This rate has slowly risen as we accept for operation patients with increasingly poor ventricular function. Just as patients with Class IV mitral valve disease carry a high operative risk, so will patients in a similar class of coronary artery disease. DR. JOHNSON: Thirty-six percent of our patients wlio have undergone vein graft operations have also had arterial implants. We now even have several angiograms on patients with double grafts in two arteries in whom the implants a year later filled a tliird artery. I think a single graft to an anterior descending coronary artery in a patient with diffuse circumflex coronary artery disease is inadequate. In this situation simultaneous implants are performed with the anterior graft. VOL. 10, NO. 2, AUGUST,

12 JOHNSON ET AL. Our patency rate has run consistently high. If we have one or two good vein grafts satisfying the area of the ischemia, we do not do implants at the present time, whereas initially we did perform implants on most of these patients. We have had no experience with internal mammary artery and coronary artery hookup. The highest flow through an internal mammary artery that I have seen reported was 80 ml. per minute. When the whole anterior descending artery is filled distal to a proximal block, the flow through a vein graft is 100 to 180 ml. per minute. We do not think that the mammary artery can provide this kind of flow. Double or triple left-sided grafts are commonly used. The mammary artery is much less versatile when multiple areas need reconstruction of flow. We have seen many anterior and right coronary arteries which were not visualized by left or right angiograms and which were completely collapsed at operation. Yet in the arteries satisfactory veins were inserted with good distal runoff. Angiograms are completely essential in planning the operation, but the absence of distal filling and distal runoff does not rule out the possibility of finding a good artery at operation. 152 THE ANNALS OF THORACIC SURGERY