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Direct Myocardial Revascularization
Symposium on Cardiac and Renal Surgery
Direct Myocardial Revascularization
Rene G. Favaloro, M.D.
Direct myocardial revascularization has been performed at the Cleveland Clinic since January 1962. Until April 1967 the pericardial patch-graft technique was applied. 4 Results of a study of 663 patients who underwent surgery reveal that (1) a significant number (40 per cent) of those patients who were operated on by this technique for direct repair of a dominant right coronary artery did not obtain the benefit expected; and (2) a discouragingly high operative mortality rate (65 per cent) was associated with the direct approach on the left coronary artery. This observation, plus the fact that in some instances the distal portion of the coronary circulation was visualized by collateral circulation when the proximal segment was totally occluded, led me to consider the possibility of utilizing the saphenous vein graft technique, predicated by the successful use of this approach for several years in peripheral vascular reconstruction and the experimental work done by M urray7.8 and by Sauvage and associates. 9 The first clinical application of the procedure was undertaken in May 1967, and from that time until March 1, 1971, 1756 patients have undergone surgery (Table 1).
Table 1.
Results of Saphenous Vein Graft Technique in 1756 Patients
SAPHENOUS VEIN GRAFT*
Right coronary artery Left coronary artery Multiple (double, triple, quadruple)
NO. OF
HOSPITAL
PATIENTS
DEATHS
(PER CENT)
665 590 501 1,756
26 15 23
(3.9) (2.5) (4.5)
"2371 grafts
From the Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation Surgical Clinics of North America- Vol. 51, No.5, October 1971
1035
1036
RENE
G.
FAVALORO
OPERA TIVE TECHNIQUE Since the original communications ,2, 3 several changes have been made in the procedure,5,6 and at present the procedure is well standardized with only minor variations. Saphenous vein graft interpositions are rarely performed, and when done, it is in an exceptional patient with a sharply localized obstruction in the mid portion of the right coronary artery. The saphenous vein bypass technique, as it is most commonly used, will be described in detail.
Preparation of the Vein If one bypass is indicated, one leg is prepared for surgery; if multiple bypasses are indicated, both legs are prepared to the ankle. The saphenous vein is dissected through an incision on the upper portion of the groin. If the saphenous vein is of a suitable size, we elongate the incision. If it is too large, another incision is made in the mid thigh. We do not hesitate to go below the knee or even to the ankle to obtain a vein of smaller diameter. A saphenous vein that is too large in diameter is not used in order to prevent turbulence and possible thrombosis of the graft. We prefer meticulous sharp dissection, making a long skin incision, to avoid finger dissection with concomitant vein damage. The extra time spent in this maneuver is always worthwhile. After the vein is removed, the proximal segment is clamped with a regular hemostat, and the vein is injected with a small amount of normal saline solution to prevent overdistention. Small side branches can be detected and closed with fine 5-0 or 6-0 silk sutures. Most of the adventitia is trimmed. When the patient is stable, it is advisable to perform the dissection and preparation of the vein with a separate table. After the vein is removed and the incision carefully closed to avoid hematoma, an operative field on the chest is prepared and a regular operating table is used.
Cardiopulmonary Bypass Except in a few patients with localized obstruction in the middle or beginning of the distal thirds of the right coronary artery, all the operations are performed under cardiopulmonary bypass. A routine midline trans-sternal thoracotomy is performed. When bypasses are planned for the circumflex coronary artery, the incision is elongated midway to the umbilicus to obtain enough separation of the sternal edges. At present the aorta is cannulated in every patient. For this purpose, a No. 24 or 26 aortic cannula':' is inserted in the uppermost portion of the ascending aorta close to the origin of the innominate artery, thus giving ample space on the anterolateral wall of the aorta, even if multiple grafts are indicated. Individual cannulations are performed for the vena cava. A vent is inserted in the left atrium through the right superior pulmonary vein when bypasses are performed to the right coronary artery or to the anterior descending coronary artery. For circumflex bypasses, "'United States Catheter and Instrument Corporation, Glens Falls, New York, 12801
DIRECT MYOCARDIAL REVASCULARIZATION
1037
the vent is placed at the apex of the left ventricle, knowing in advance that the heart must be fully elevated and distorted. Extracorporeal circulation is begun under normothermia with hemodilution technique. Induced fibrillation is performed routinely, and intermittent cross-clamping of the aorta for 15 to 20 minutes (enough time to perform a single anastomosis) is applied in the great majority of patients.
Preparation of the Site for the Anastomosis The location of the distal anastomosis is carefully selected prior to the operation by reviewing the coronary cineangiograms. It is seldom that we must change our initial approach. On the left coronary artery (anterior descending branch, diagonal branches of the anterior descending coronary artery, lateral and diaphragmatic branches of the circumflex coronary artery), we do not dissect the artery from the surrounding tissue except in those rare cases when the artery is deep in the muscle. In contrast, anastomoses to the distal distribution of the right coronary artery and main circumflex coronary artery require some dissection because of the depth of the localization. Two 2-0 silk sutures are passed around the arteries and 6-0 silk sutures are placed at either side of the artery, taking only the epicardium and subepicardial fat. By delicate tension on these sutures, the artery is held immobile, and using a knife with a delicate No. 15 bistoury blade, a small longitudinal incision is made layer by layer from the outside. A right-angled scissors is utilized to enlarge the opening (Fig. 1).
Figure 1. Dissection of the coronary artery is avoided on the left coronary artery and its divisions, except when the anastomosis is performed on the main circumflex coronary artery. A No. 15 bistoury blade is utilized to open the artery layer by layer from outside.
1038
RENE
G.
FAVALORO
End-to-Side Anastomosis This type of anastomosis can be done with interrupted or running sutures. We prefer the interrupted sutures for small arteries. Running sutures are employed only when the lumen is large enough and they are safe to use. When interrupted sutures are used, all of them are passed through the site of the arteriotomy and held in place in the operative field by individual mosquito clamps. The vein which was reversed to avoid impaired blood flow from the valve is transected at a 45 degree angle, and the lumen is enlarged by a small longitudinal incision. We begin the anastomosis at the proximal end of the arteriotomy for bypasses to the right coronary artery, distal distribution of the circumflex coronary artery, and middle or distal thirds of the anterior descending coronary artery. Anastomoses to the proximal portion of the anterior descending coronary artery or main circumflex coronary artery should start in the middle of the medial side of the arteriotomy to avoid kinking of the graft. One by one the stitches are passed through the vein and tied. Doubleend 6-0 silk sutures are used (Fig. 2). If running sutures are to be employed, we prefer Ethiflex 6-0 sutures with a delicate needle. Two stitches with double-end needles are passed at the proximal and distal ends of the arteriotomy, through the vein, and are tied. At that point, both are running to the mid portion of the arteriotomy.
End-to-End Anastomosis The end-to-end anastomosis is seldom used, and only for reconstruction of totally occluded arteries; the anastomosis is done with interrupted 6-0 silk sutures in a racket fashion. All distal anastomoses are performed with the heart fibrillating and fully decompressed.
Figure 2. The anastomosis starts at the proximal end of the arteriotomy (left) except for the proximal segment of the anterior discending and circumflex coronary arteries. To avoid kinking of the graft, the anastomosis should start in the middle of the medial side of the arteriotomy (right).
DIRECT MYOCARDIAL REVASCULARIZATION
1039
Proximal Anastomosis After the distal anastomosis is performed, the heart is given a directcurrent countershock and is placed on partial bypass. The vent is slowed down. This maneuver allows us to select the proper length of the graft and the proper angulation. Grafts that are too long have a tendency to kink, and grafts that are too short will distort the distal anastomosis. We prefer to perform the proximal anastomosis on the medial side of the ascending aorta for bypasses to the left coronary artery and its divisions. Bypasses to the right coronary artery are connected in the middle of the lower portion of the ascending aorta. A partial aortic clamp is applied and a portion of the aortic wall is resected in a triangular shape. The base is toward the pulmonary artery for bypasses to the left coronary artery; for bypasses to the right coronary artery it is toward the root of the aorta. The proximal anastomosis is performed with running sutures (6-0 Ethiflex), always starting at the base of the triangular resection to avoid kinking. We prefer individual openings on the proximal anastomosis whenever possible; nevertheless, in triple or quadruple bypasses, the graft to the circumflex coronary artery is first connected to the aorta and the left bypasses are connected at different sites on the vein in a Y anastomosis. If the ascending aorta shows significant atheromatous changes with severe thickening of the wall, it is advisable to clamp the aorta close to the aortic cannulation and perform the anastomosis with the aorta totally clamped and fully decompressed (Fig. 3).
INDICATIONS As a general rule, direct myocardial revascularization by the saphenous vein graft technique is indicated in severe subtotal occlusions, 70 per cent or more, or totally occluded arteries with good distal runoff
Figure 3. Proximal anastomoses are performed with running sutures. The opening is made in the middle of the lower portion of the ascending aorta for grafting to the right coronary artery (left) and on the medial side of the ascending aorta for grafting to the left coronary artery (right).
1040
RENE
G.
FAVALORO
(narrowing less than 50 per cent). Our present operative technique allows us to perform bypasses anywhere in the coronary circulation (right coronary artery, posterior descending and atrioventricular branches of the right coronary artery, anterior descending coronary artery, diagonal branches of the anterior descending coronary artery, main circumflex coronary artery, lateral and diaphragmatic branches of the ci~cumflex coronary artery). The ideal patient will show good contraction of the left ventricle on a routine left cineventriculogram with normal end-diastolic pressure, and cardiac output within normal limits. Nevertheless, a significant number of patients are being evaluated after several myocardial infarctions and will show, in addition to the widespread disease in the coronary circulation, impaired contraction of the left ventricle with elevation of the end diastolic pressure and diminished cardiac output. If careful evaluation of the coronary cineangiograms reveals the feasi-
Table 2.
Mortality Among 115 Saphenous Vein Graft Procedures NO. OF
HOSPITAL
PATIENTS
DEATHS
Saphenous vein graft to: RCA* RCA and LIM implant RCA and LAD RCA and LAD and LIM implant RCA and LAD and Circ RCA and LAD and Circ and ventricular aneurysmectomy RCA and LAD and Circ and Diag RCA and Circ RCA and Circ and LIM implant RCA and ventricular aneurysmectomy RCA and Vent scar LAD LAD and LIM implant LAD and double internal mammary artery implant LAD and Circ LAD and Circ and LIM implant LAD and ventricular aneurysmectomy LAD and Diag LAD and Diag and LIM implant Circ Circ and ventricular aneurysmectomy Circ and aortic valve replacement Diag and LIM implant and ventricular aneurysmectomy Lat Circ and A-V Br Circ and ventricular aneurysmectomy Ventricular aneurysmectomy ':'Abbreviations: A-V Br Circ, atrioventricular branch of circumflex coronary artery Circ, circumflex coronary artery Diag, diagonal branch of anterior descending coronary artery LAD, left anterior descending coronary artery Lat Circ, lateral branch of circumflex coronary artery LIM, left internal mammary artery RCA, right coronary artery Vent scar ventricular scar
9 6 13 6 12
4 2 2 2 12 8 14 2 3 3 4 1
5
DIRECT MYOCARDIAL REVASCULARIZATION
1041
bility of multiple bypasses, the operation should be performed as the only chance for recuperation. Another indication for the saphenous vein graft technique is the acute phase of coronary insufficiency. This can be divided as follows: (1) pending myocardial infarction, (2) acute myocardial infarction without cardiogenic shock, and (3) acute myocardial infarction with cardiogenic shock. In the first category, there is no doubt that admission to the coronary care unit is not enough. Emergency coronary cineangiography should be performed, and the bypass operation can prevent myocardial injury. Following this policy, 19 such patients were operated upon at the Cleveland Clinic Hospital, with 2 hospital deaths. The other 17 patients had uneventful postoperative courses and are free of angina. That coronary cineangiography can be performed during an episode of acute myocardial infarction has been demonstrated by Begg1 and confirmed by our colleagues in the Cardiac Laboratory of the Cleveland Clinic. Valuable information can be obtained. If the patient is in cardiogenic shock, partial cardiopulmonary bypass can be instituted and the studies can be performed while the failing heart is supported. Ten patients underwent myocardial revascularization while they were suffering acute myocardial infarctions, with one hospital death. The postoperative coronary Cineangiographic studies have shown that if the operation is performed within 3 to 4 hours, the vast majority of the heart muscle can be saved. This is a new field, clinical experience is extremely limited, and only further application of the technique will determine the exact role of saphenous vein graft bypasses in patients with acute myocardial infarction. There is no doubt that in some instances it can be life-saving for the patient, as was demonstrated in 3 patients in our series.
CONCLUSION The saphenous vein graft has opened a new era in myocardial revascularization. For the first time we are allowed to increase myocardial perfusion immediately. At present, the operation can be performed with a low operative mortality as exemplified by 115 operations performed in February 1971 (Table 2). The reasons for the low operative risk can be summarized as follows: (1) high-quality coronary cineangiograms which provide a precise evaluation and selection of the best operation for each patient; (2) excellent anesthesia with the utilization of methoxyflurane; (3) cardiopulmonary bypass performed at normothermia with hemodilution technique; (4) standardization of the operative technique, which allows the operating team to perform the operation in the simplest manner and in minimal time; (5) careful evaluation of the blood volume by left atrial pressure measurement at the end of the operation or in the immediate postoperative period; (6) liberal use of coronary vasodilators, during and after operation (isosorbide dinitrate and nitroglycerin); (7) prevention or correction of hypokalemia which is the most common cause of ventricular arrhythmia; (8) rapid intravenous digitalization when signs of cardiac failure are manifested.
1042
RENE
G.
FAVALORO
The long follow-up studies which will be discussed in the next article have been most gratifying. The majority of patients are fully recovered, enjoy a normal life, and work full time. As yet, no aneurysmal dilatation of the grafts has been noted (the longest repeat coronary cineangiographic study is 39 months postoperatively), and the rate of late thrombosis is minimal. Early technical problems have been corrected, and I firmly believe that there will be further improvement in the percentage of good results.
REFERENCES 1. Begg, F. R., Kooros, M. A., Magovern, G. J., Kent, E. M., Brent, L. B., and Cushing, w. B.: The hemodynamics and coronary arteriography patterns during acute myocardial infarction. J. Thorac. Cardiovasc. Surg., 58: 178, 1969. 2. Favaloro, R. G.: Saphenous vein autograft replacement of severe segmental coronary artery occlusion-operative technique. Ann. Thorac. Surg., 5:334, 1968. 3. Favaloro, R. G.: Saphenous vein graft in the surgical treatment of coronary artery disease. J. Thorac. Cardiovasc. Surg., 58:178, 1969. 4. Favaloro, R. G.: Surgical Treatment of Coronary Arteriosclerosis. Baltimore, Williams and Wilkins, 1970. 5. Favaloro, R. G., Effler, D. B., Groves, L. K., Sheldon, W. C .. Shirey, E. K., and Sones, F. M., Jr.: Severe segmented obstruction of the left main coronary artery and its divisionsSurgical treatment by the saphenous vein graft technique. J. Thorac. Cardiovas. Surg., 60:469, 1970. 6. Favaloro, R. G., Effler, D. B., Groves, L. K., Sheldon, W. C., and Sones, F. M., Jr.: Direct myocardial revascularization by saphenous vein graft-present operative technique and indications. Ann. Thorac. Surg., 10:97,1970. 7. Murray, G.: Surgery of coronary heart disease. Angiology, 4:526, 1953. 8. Murray, G.: The surgical treatment of coronary thrombosis. Canad. Med. Assoc. J., 67: 100,1952. 9. Sauvage, L. R., Wood, S. J., Eyer, K. M., and Bill, A. H., Jr.: Experimental coronary artery surgery: Preliminary observations of bypass venous grafts, longitudinal arteriotomies, and end-to-end anastomoses. J. Thorac. Cardiovasc. Surg., 46:826, 1963.
Direct Myocardial Revascularization
Rene G. Favaloro, M.D.
Direct myocardial revascularization has been performed at the Cleveland Clinic since January 1962. Until April 1967 the pericardial patch-graft technique was applied. 4 Results of a study of 663 patients who underwent surgery reveal that (1) a significant number (40 per cent) of those patients who were operated on by this technique for direct repair of a dominant right coronary artery did not obtain the benefit expected; and (2) a discouragingly high operative mortality rate (65 per cent) was associated with the direct approach on the left coronary artery. This observation, plus the fact that in some instances the distal portion of the coronary circulation was visualized by collateral circulation when the proximal segment was totally occluded, led me to consider the possibility of utilizing the saphenous vein graft technique, predicated by the successful use of this approach for several years in peripheral vascular reconstruction and the experimental work done by M urray7.8 and by Sauvage and associates. 9 The first clinical application of the procedure was undertaken in May 1967, and from that time until March 1, 1971, 1756 patients have undergone surgery (Table 1).
Table 1.
Results of Saphenous Vein Graft Technique in 1756 Patients
SAPHENOUS VEIN GRAFT*
Right coronary artery Left coronary artery Multiple (double, triple, quadruple)
NO. OF
HOSPITAL
PATIENTS
DEATHS
(PER CENT)
665 590 501 1,756
26 15 23
(3.9) (2.5) (4.5)
"2371 grafts
From the Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation Surgical Clinics of North America- Vol. 51, No.5, October 1971
1035
1036
RENE
G.
FAVALORO
OPERA TIVE TECHNIQUE Since the original communications ,2, 3 several changes have been made in the procedure,5,6 and at present the procedure is well standardized with only minor variations. Saphenous vein graft interpositions are rarely performed, and when done, it is in an exceptional patient with a sharply localized obstruction in the mid portion of the right coronary artery. The saphenous vein bypass technique, as it is most commonly used, will be described in detail.
Preparation of the Vein If one bypass is indicated, one leg is prepared for surgery; if multiple bypasses are indicated, both legs are prepared to the ankle. The saphenous vein is dissected through an incision on the upper portion of the groin. If the saphenous vein is of a suitable size, we elongate the incision. If it is too large, another incision is made in the mid thigh. We do not hesitate to go below the knee or even to the ankle to obtain a vein of smaller diameter. A saphenous vein that is too large in diameter is not used in order to prevent turbulence and possible thrombosis of the graft. We prefer meticulous sharp dissection, making a long skin incision, to avoid finger dissection with concomitant vein damage. The extra time spent in this maneuver is always worthwhile. After the vein is removed, the proximal segment is clamped with a regular hemostat, and the vein is injected with a small amount of normal saline solution to prevent overdistention. Small side branches can be detected and closed with fine 5-0 or 6-0 silk sutures. Most of the adventitia is trimmed. When the patient is stable, it is advisable to perform the dissection and preparation of the vein with a separate table. After the vein is removed and the incision carefully closed to avoid hematoma, an operative field on the chest is prepared and a regular operating table is used.
Cardiopulmonary Bypass Except in a few patients with localized obstruction in the middle or beginning of the distal thirds of the right coronary artery, all the operations are performed under cardiopulmonary bypass. A routine midline trans-sternal thoracotomy is performed. When bypasses are planned for the circumflex coronary artery, the incision is elongated midway to the umbilicus to obtain enough separation of the sternal edges. At present the aorta is cannulated in every patient. For this purpose, a No. 24 or 26 aortic cannula':' is inserted in the uppermost portion of the ascending aorta close to the origin of the innominate artery, thus giving ample space on the anterolateral wall of the aorta, even if multiple grafts are indicated. Individual cannulations are performed for the vena cava. A vent is inserted in the left atrium through the right superior pulmonary vein when bypasses are performed to the right coronary artery or to the anterior descending coronary artery. For circumflex bypasses, "'United States Catheter and Instrument Corporation, Glens Falls, New York, 12801
DIRECT MYOCARDIAL REVASCULARIZATION
1037
the vent is placed at the apex of the left ventricle, knowing in advance that the heart must be fully elevated and distorted. Extracorporeal circulation is begun under normothermia with hemodilution technique. Induced fibrillation is performed routinely, and intermittent cross-clamping of the aorta for 15 to 20 minutes (enough time to perform a single anastomosis) is applied in the great majority of patients.
Preparation of the Site for the Anastomosis The location of the distal anastomosis is carefully selected prior to the operation by reviewing the coronary cineangiograms. It is seldom that we must change our initial approach. On the left coronary artery (anterior descending branch, diagonal branches of the anterior descending coronary artery, lateral and diaphragmatic branches of the circumflex coronary artery), we do not dissect the artery from the surrounding tissue except in those rare cases when the artery is deep in the muscle. In contrast, anastomoses to the distal distribution of the right coronary artery and main circumflex coronary artery require some dissection because of the depth of the localization. Two 2-0 silk sutures are passed around the arteries and 6-0 silk sutures are placed at either side of the artery, taking only the epicardium and subepicardial fat. By delicate tension on these sutures, the artery is held immobile, and using a knife with a delicate No. 15 bistoury blade, a small longitudinal incision is made layer by layer from the outside. A right-angled scissors is utilized to enlarge the opening (Fig. 1).
Figure 1. Dissection of the coronary artery is avoided on the left coronary artery and its divisions, except when the anastomosis is performed on the main circumflex coronary artery. A No. 15 bistoury blade is utilized to open the artery layer by layer from outside.
1038
RENE
G.
FAVALORO
End-to-Side Anastomosis This type of anastomosis can be done with interrupted or running sutures. We prefer the interrupted sutures for small arteries. Running sutures are employed only when the lumen is large enough and they are safe to use. When interrupted sutures are used, all of them are passed through the site of the arteriotomy and held in place in the operative field by individual mosquito clamps. The vein which was reversed to avoid impaired blood flow from the valve is transected at a 45 degree angle, and the lumen is enlarged by a small longitudinal incision. We begin the anastomosis at the proximal end of the arteriotomy for bypasses to the right coronary artery, distal distribution of the circumflex coronary artery, and middle or distal thirds of the anterior descending coronary artery. Anastomoses to the proximal portion of the anterior descending coronary artery or main circumflex coronary artery should start in the middle of the medial side of the arteriotomy to avoid kinking of the graft. One by one the stitches are passed through the vein and tied. Doubleend 6-0 silk sutures are used (Fig. 2). If running sutures are to be employed, we prefer Ethiflex 6-0 sutures with a delicate needle. Two stitches with double-end needles are passed at the proximal and distal ends of the arteriotomy, through the vein, and are tied. At that point, both are running to the mid portion of the arteriotomy.
End-to-End Anastomosis The end-to-end anastomosis is seldom used, and only for reconstruction of totally occluded arteries; the anastomosis is done with interrupted 6-0 silk sutures in a racket fashion. All distal anastomoses are performed with the heart fibrillating and fully decompressed.
Figure 2. The anastomosis starts at the proximal end of the arteriotomy (left) except for the proximal segment of the anterior discending and circumflex coronary arteries. To avoid kinking of the graft, the anastomosis should start in the middle of the medial side of the arteriotomy (right).
DIRECT MYOCARDIAL REVASCULARIZATION
1039
Proximal Anastomosis After the distal anastomosis is performed, the heart is given a directcurrent countershock and is placed on partial bypass. The vent is slowed down. This maneuver allows us to select the proper length of the graft and the proper angulation. Grafts that are too long have a tendency to kink, and grafts that are too short will distort the distal anastomosis. We prefer to perform the proximal anastomosis on the medial side of the ascending aorta for bypasses to the left coronary artery and its divisions. Bypasses to the right coronary artery are connected in the middle of the lower portion of the ascending aorta. A partial aortic clamp is applied and a portion of the aortic wall is resected in a triangular shape. The base is toward the pulmonary artery for bypasses to the left coronary artery; for bypasses to the right coronary artery it is toward the root of the aorta. The proximal anastomosis is performed with running sutures (6-0 Ethiflex), always starting at the base of the triangular resection to avoid kinking. We prefer individual openings on the proximal anastomosis whenever possible; nevertheless, in triple or quadruple bypasses, the graft to the circumflex coronary artery is first connected to the aorta and the left bypasses are connected at different sites on the vein in a Y anastomosis. If the ascending aorta shows significant atheromatous changes with severe thickening of the wall, it is advisable to clamp the aorta close to the aortic cannulation and perform the anastomosis with the aorta totally clamped and fully decompressed (Fig. 3).
INDICATIONS As a general rule, direct myocardial revascularization by the saphenous vein graft technique is indicated in severe subtotal occlusions, 70 per cent or more, or totally occluded arteries with good distal runoff
Figure 3. Proximal anastomoses are performed with running sutures. The opening is made in the middle of the lower portion of the ascending aorta for grafting to the right coronary artery (left) and on the medial side of the ascending aorta for grafting to the left coronary artery (right).
1040
RENE
G.
FAVALORO
(narrowing less than 50 per cent). Our present operative technique allows us to perform bypasses anywhere in the coronary circulation (right coronary artery, posterior descending and atrioventricular branches of the right coronary artery, anterior descending coronary artery, diagonal branches of the anterior descending coronary artery, main circumflex coronary artery, lateral and diaphragmatic branches of the ci~cumflex coronary artery). The ideal patient will show good contraction of the left ventricle on a routine left cineventriculogram with normal end-diastolic pressure, and cardiac output within normal limits. Nevertheless, a significant number of patients are being evaluated after several myocardial infarctions and will show, in addition to the widespread disease in the coronary circulation, impaired contraction of the left ventricle with elevation of the end diastolic pressure and diminished cardiac output. If careful evaluation of the coronary cineangiograms reveals the feasi-
Table 2.
Mortality Among 115 Saphenous Vein Graft Procedures NO. OF
HOSPITAL
PATIENTS
DEATHS
Saphenous vein graft to: RCA* RCA and LIM implant RCA and LAD RCA and LAD and LIM implant RCA and LAD and Circ RCA and LAD and Circ and ventricular aneurysmectomy RCA and LAD and Circ and Diag RCA and Circ RCA and Circ and LIM implant RCA and ventricular aneurysmectomy RCA and Vent scar LAD LAD and LIM implant LAD and double internal mammary artery implant LAD and Circ LAD and Circ and LIM implant LAD and ventricular aneurysmectomy LAD and Diag LAD and Diag and LIM implant Circ Circ and ventricular aneurysmectomy Circ and aortic valve replacement Diag and LIM implant and ventricular aneurysmectomy Lat Circ and A-V Br Circ and ventricular aneurysmectomy Ventricular aneurysmectomy ':'Abbreviations: A-V Br Circ, atrioventricular branch of circumflex coronary artery Circ, circumflex coronary artery Diag, diagonal branch of anterior descending coronary artery LAD, left anterior descending coronary artery Lat Circ, lateral branch of circumflex coronary artery LIM, left internal mammary artery RCA, right coronary artery Vent scar ventricular scar
9 6 13 6 12
4 2 2 2 12 8 14 2 3 3 4 1
5
DIRECT MYOCARDIAL REVASCULARIZATION
1041
bility of multiple bypasses, the operation should be performed as the only chance for recuperation. Another indication for the saphenous vein graft technique is the acute phase of coronary insufficiency. This can be divided as follows: (1) pending myocardial infarction, (2) acute myocardial infarction without cardiogenic shock, and (3) acute myocardial infarction with cardiogenic shock. In the first category, there is no doubt that admission to the coronary care unit is not enough. Emergency coronary cineangiography should be performed, and the bypass operation can prevent myocardial injury. Following this policy, 19 such patients were operated upon at the Cleveland Clinic Hospital, with 2 hospital deaths. The other 17 patients had uneventful postoperative courses and are free of angina. That coronary cineangiography can be performed during an episode of acute myocardial infarction has been demonstrated by Begg1 and confirmed by our colleagues in the Cardiac Laboratory of the Cleveland Clinic. Valuable information can be obtained. If the patient is in cardiogenic shock, partial cardiopulmonary bypass can be instituted and the studies can be performed while the failing heart is supported. Ten patients underwent myocardial revascularization while they were suffering acute myocardial infarctions, with one hospital death. The postoperative coronary Cineangiographic studies have shown that if the operation is performed within 3 to 4 hours, the vast majority of the heart muscle can be saved. This is a new field, clinical experience is extremely limited, and only further application of the technique will determine the exact role of saphenous vein graft bypasses in patients with acute myocardial infarction. There is no doubt that in some instances it can be life-saving for the patient, as was demonstrated in 3 patients in our series.
CONCLUSION The saphenous vein graft has opened a new era in myocardial revascularization. For the first time we are allowed to increase myocardial perfusion immediately. At present, the operation can be performed with a low operative mortality as exemplified by 115 operations performed in February 1971 (Table 2). The reasons for the low operative risk can be summarized as follows: (1) high-quality coronary cineangiograms which provide a precise evaluation and selection of the best operation for each patient; (2) excellent anesthesia with the utilization of methoxyflurane; (3) cardiopulmonary bypass performed at normothermia with hemodilution technique; (4) standardization of the operative technique, which allows the operating team to perform the operation in the simplest manner and in minimal time; (5) careful evaluation of the blood volume by left atrial pressure measurement at the end of the operation or in the immediate postoperative period; (6) liberal use of coronary vasodilators, during and after operation (isosorbide dinitrate and nitroglycerin); (7) prevention or correction of hypokalemia which is the most common cause of ventricular arrhythmia; (8) rapid intravenous digitalization when signs of cardiac failure are manifested.
1042
RENE
G.
FAVALORO
The long follow-up studies which will be discussed in the next article have been most gratifying. The majority of patients are fully recovered, enjoy a normal life, and work full time. As yet, no aneurysmal dilatation of the grafts has been noted (the longest repeat coronary cineangiographic study is 39 months postoperatively), and the rate of late thrombosis is minimal. Early technical problems have been corrected, and I firmly believe that there will be further improvement in the percentage of good results.
REFERENCES 1. Begg, F. R., Kooros, M. A., Magovern, G. J., Kent, E. M., Brent, L. B., and Cushing, w. B.: The hemodynamics and coronary arteriography patterns during acute myocardial infarction. J. Thorac. Cardiovasc. Surg., 58: 178, 1969. 2. Favaloro, R. G.: Saphenous vein autograft replacement of severe segmental coronary artery occlusion-operative technique. Ann. Thorac. Surg., 5:334, 1968. 3. Favaloro, R. G.: Saphenous vein graft in the surgical treatment of coronary artery disease. J. Thorac. Cardiovasc. Surg., 58:178, 1969. 4. Favaloro, R. G.: Surgical Treatment of Coronary Arteriosclerosis. Baltimore, Williams and Wilkins, 1970. 5. Favaloro, R. G., Effler, D. B., Groves, L. K., Sheldon, W. C .. Shirey, E. K., and Sones, F. M., Jr.: Severe segmented obstruction of the left main coronary artery and its divisionsSurgical treatment by the saphenous vein graft technique. J. Thorac. Cardiovas. Surg., 60:469, 1970. 6. Favaloro, R. G., Effler, D. B., Groves, L. K., Sheldon, W. C., and Sones, F. M., Jr.: Direct myocardial revascularization by saphenous vein graft-present operative technique and indications. Ann. Thorac. Surg., 10:97,1970. 7. Murray, G.: Surgery of coronary heart disease. Angiology, 4:526, 1953. 8. Murray, G.: The surgical treatment of coronary thrombosis. Canad. Med. Assoc. J., 67: 100,1952. 9. Sauvage, L. R., Wood, S. J., Eyer, K. M., and Bill, A. H., Jr.: Experimental coronary artery surgery: Preliminary observations of bypass venous grafts, longitudinal arteriotomies, and end-to-end anastomoses. J. Thorac. Cardiovasc. Surg., 46:826, 1963.