- Email: [email protected]
Aortic valve replacement and aorta-coronary bypass surgery
Aortic valve replacement and aorta-coronary bypass surgery Results with perfusion of proximal and distal coronary arteries The results in 80 patients undergoing simultaneous aortic valve replacement and aorta-coronary saphenous vein bypass grafting were analyzed to assess the effect of operative technique. The over-all operative mortality rate of 6.3 percent (five of 80) did not differ significantly from our results with aortic valve replacement alone. All patients who had isolated aortic valve replacement were operated upon with moderate hypothermia. The combined operation was performed in two ways. Thirty-one patients had aortic valve replacement prior to bypass grafting with intermittent coronary ostial perfusion. There were two deaths (6.5 percent), and five myocardial infarctions (16.1 percent) were diagnosed by standard electrocardiographic and enzyme criteria. More recently, 49 patients have undergone bypass grafting prior to aortic valve replacement. The proximal ends of the grafts were either anastomosed high on the aortic root or else were individually cannulated to provide continuous distal perfusion during subsequent aortic valve replacement, with continuous coronary ostial perfusion. There were three operative deaths (6.1 percent) and one myocardial infarction (2.0 percent). The risk of combined aortic valve replacement and coronary bypass need be no greater than the risk of aortic valve replacement alone. Our experience suggests that myocardial perfusion distal to significant coronary artery stenoses reduces the risk of myocardial infarction in patients with coronary artery disease requiring aortic valve replacement.
Quentin Macmanus, M.D., Gary Grunkemeier, Ph.D., Louis Lambert, M.S., Charles Dietl, M.D., and Albert Starr, M.D., Portland, Ore.
Since the report of Flemma and associates' in 1971, several centers have described their experience with combined aortic valve replacement and aorta-coronary bypass surgery. 2-10 Operative mortality has varied from 4 to 15 percent, and postoperative myocardial infarction has occurred in 3 to 21 percent of patients. There is apparently little uniformity in the management of these patients. Debate has centered about the role of coronary arteriography in angina-free patients with aortic valve disease,": 11-13 the operative techniques best suited to ensure maximal myocardial protection,2-7 and the question of whether or not concomitant aorta-coronary bypass graft surgery influences the results of aortic valve replacernent.v !? In the hopes of moving toward some consensus on the proper approach to the treatment of these patients, From the Division of Cardiopulmonary Surgery, University of Oregon Health Sciences Center, Portland, Ore. 9720 I. Supported by U.S. Public Health Service Grant No. HL-16461. Received for publication Dec. 13, 1977.
we have examined our experience with concomitant aortic valve replacement and aorta-coronary bypass surgery.
Patients and methods From January, 1970, to January, 1977, 80 patients underwent isolated primary aortic valve replacement with concomitant aorta-coronary saphenous vein bypass grafting at S1. Vincent Hospital, Portland, Oregon. Clinical presentation varied from absence of symptoms in the presence of significant aortic valve gradients and coronary lesions (defined as greater than 50 percent stenosis) to Class IV* congestive heart failure with severe angina. Clinical and diagnostic data are listed in Table I. On the basis of clinical presentation, catheterization data, and operative findings, patients were categorized as having primarily aortic stenosis, aortic insufficiency, or mixed lesions. The nature of the lesion, as well as the etiology, can be found in Table II. The principal
Accepted for publication Jan. 13, 1978.
0022-5223/78/0675-0865$00.50/0 © 1978 The C. V. Mosby Co.
*New York Heart Association functional classification.
865
The Journal of Thoracic and Cardiovascular Surgery
866 Macmanus et al.
Table I. Clinical and diagnostic data No. of patients Male Female Age (yr.) Mean Range Severity of angina None Mild Moderate Severe Prior myocardial infarction N.Y.H.A. functional c1ass* Class I Class II Class III Class IV Catheterization datat Mean RAP (mm. Hg) RVP (mm. Hg) PAP (mm. Hg) Mean PAP (mm. Hg) LVP (mm. Hg) Aortic pressure (mm. Hg) Cardiac index (L./min./sq. M.) PVR (units) AS gradient (mm. Hg)
Table II. Nature and etiology of aortic valve lesions 80 61 19 63.1 44-81 12 14 36 18 10
23 (29)* 18 (22) 35 (44) 4 ( 5) 4.5 (50)t 37/6 (54) 35/14 (58) 22.1 (50) 183/18 (58) 137/66 (68) 2.8 (41) 2.0 69.6 (35)
Legend: N.Y.H.A., New York Heart Association. RAP, Right atrial pressure. RVP, Right ventricular pressure. PAP, Pulmonary arterial pressure. LVP, Left ventricular pressure. PVR, Pulmonary vascular resistance. AS, Aortic stenosis. 'Figures in parentheses indicate percentages. tFigures in parentheses indicate the number of values.
indication for aortic valve replacement can be found in Table III. A total of 120 aorta-coronary saphenous vein bypass grafts were placed at the time of aortic valve replacement. The distribution of vein grafts is listed in Table IV. Additionally, 20 patients underwent concomitant operations, the nature of which is listed in Table V.
Operative technique Our operative technique for aortic valve replacement comprises high-flow cardiopulmonary bypass with moderate (30 0 to 32 0 C.) systemic hypothermia. A vent in the apex of the left ventricle is routinely employed. The aortic root is opened transversely, and the incision is extended toward the noncoronary cusp if necessary for additional exposure. The pericardial sac is irrigated briefly with 4 0 C. Ringer's lactate. The diseased valve is sharply excised and sutures are placed in the aortic annulus. The coronary arteries are cannulated and the 0 0 heart is perfused with blood at 30 to 32 C. After a few minutes, the heart is electrically defibrillated and main-
Nature
Etiology
Lesion
No.
Lesion
No.
Aortic stenosis Aortic insufficiency Mixed
44 20 16
Bicuspid Rheumatic Atherosclerotic
28 II 41
Table III. Principal indication for aortic valve replacement Indication
No.
Angina and congestive heart failure Angina Angina, syncope, and congestive heart failure Free of angina Asymptomatic Congestive heart failure Syncope and congestive heart failure
36 17 16 I1 4 5 2
Table IV. Distribution of vein grafts Coronary artery
Right Left anterior descending Diagonal Obtuse marginal Total Avg. per patient
I
No. of vein grafts
43 51 2 24 120 I.5
tained in a beating state while the prosthesis is being sewn into place. Following valve replacement, the heart is fibrillated, the aortotomy is closed and all air is evacuated. The heart is then defibrillated and the catheter is removed from the left ventricle. The safety and efficacy of this technique have been widely documented. 14 The management of the associated vein grafts has been in a gradual state of evolution. Early in our experience with the combined operation, vein grafts were performed following aortic valve replacement, the distal anastomoses being done in the fibrillating heart and the proximal anastomoses in the beating heart with the aid of a partially occluding aortic clamp. Grafts were performed in sequence to ensure that the periods of ischemic arrest were kept as short as possible. This technique of replacing the aortic valve prior to performing vein graft anastomoses was used in 31 patients in this series. Although our operative results with this technique were satisfactory, 7 our continued desire to minimize the hypoxic insult to the often hypertrophied left
Volume 75 Number 6 June. 1978
Aortic valve replacement and coronary bypass
Table V. Associated surgical procedures Procedure
Right coronary endarterectomy Septal myotomy Ascending aortoplasty Left coronary endarterectomy Permanent pacemaker Resection of ventricular aneurysm Mitral commissurotomy Resection ofaneurysm ofascending aorta
I
867
No.
II 2
2 1
.~
-:::
60
Operation N • AVR • CA8G 80 o AVR only 196
"'t
1
I 1 1
M/F Mean Age 61/19 63.1 61.0 138/58
Mean Follow- up 2.6 Yr. 2.8 Yr.
20 0'-'-_-'-_-JL-_---'---_-----l_ _...L..._---'-_---' op 3 4 6
ventricular myocardium in subjects with aortic valve disease led us to modify our technique. We currently prefer to perform the grafts to the obtuse marginal and anterior descending arteries first, placing the proximal anastomoses high on the aortic root. The distal right anastomosis is performed next, the proximal anastomosis being delayed to improve exposure during valve replacement and to avoid kinking of the graft. Aortic valve replacement is then undertaken with the aortic cross-clamp below the ostia of the left-sided vein grafts to provide continuous myocardial perfusion. A perfusion catheter is placed in the vein graft on the right side, and the coronary ostia are perfused continuously as well during valve replacement. Perfusion cannulas are connected by a Y-connector and initial flow rates of 250 c.c. per minute are utilized; flow to each coronary bed, therefore, is determined only by distal resistance. Flow is adjusted up to 400 c.c. per minute as dictated by the appearance of the electrocardiogram; inadequate flow is demonstrated promptly by slowing of the heart rate or broadening of the QRS complex. Occasionally, severe aortic insufficiency or a short aortic root precludes this sequence of events, in which case the grafts to the left anterior and obtuse marginal vessels can be individually perfused following distal anastomosis; the proximal anastomosis is delayed for aortic valve replacement. This technique of placing one or all vein grafts prior to aortic valve replacement was employed in 49 patients in this series. Results Operative mortality rate. Five of 80 patients (6.3 percent) died from events temporally or causally related to the operative procedure. Two of the deaths were definitely due to intraoperative myocardial infarction. In both cases, coronary bypass followed aortic valve replacement (0.05 > P < 0.10). Another patient died of an arrhythmia 12 hours postoperatively. Findings at autopsy were unremarkable. One patient with cystic medial necrosis underwent ascending aortic aneurys-
Years
Fig. 1. Survival curves for patients having isolated aortic valve replacement (AVR) and for those having aortic valve replacement and coronary artery bypass grafting (A VR + CABG). Also shown is the expected survival curve for an age-matched and sex-matched normal population. Table VI. Causes of late death in 75
survivors of operation Cause
Congestive heart failure Myocardial infarction Thrombotic stenosis of theprosthesis Sudden, cause unknown Mycotic aneurysm Bacterial endocarditis Unrelated to cardiac disease Total
No.
2 1 I
2 I 1 2 10
morrhaphy and died on the fifth postoperative day from suture-line disruption. The fifth patient died 10 weeks after the operation from renal failure and sepsis that had resulted from gastric stress ulceration on the tenth postoperative day. Postoperative complications. Severe cardiac complications occurred in 16 patients (20.0 percent) and caused three of the deaths just described. Three patients had atrioventricular block necessitating a permanent pacemaker, three patients had ventricular fibrillation, and four patients had pulmonary edema. Myocardial infarction, defined as the appearance of new Q waves on the electrogram or persistent ST changes suggesting ischemia plus rises in LDH, SGOT, and CPK enzymes* above usual postoperative levels, occurred in six patients (7.5 percent), two of whom died. Five of the six myocardial infarctions occurred in patients who *LDH is lactic dehydrogenase; SGOT, serum glutamic oxaloacetic
transaminase; CPK, creatinine phosphokinase.
868
Macmanus et al.
had aortic valve replacement prior to vein bypass < 0.025). Late deaths. There were 10 late deaths (13.3 percent) among 75 operative survivors followed up a mean of 2.6 years. Causes of late death are listed in Table VI. A survival curve of operative survivors is shown in Fig. 1, along with the expected survival curve of an agematched and sex-matched normal population. Late functional results. All 65 long-term survivors were recently contacted by questionnaire and telephone regarding their current status. In case of ambiguity, the patient's private physician was contacted as well. Reliable information regarding angina was available in 63. Forty-one (65.1 percent) reported they never had angina, 13 (20.1 percent) had angina only with severe exertion, six others (9.5 percent) had angina with ordinary activity but felt less angina as a result of thier operation, and three patients (4.8 percent) were worse. Sixty-one patients returned sufficient information to categorize them according to the N. Y.H.A. classification for valvular disease. Thirty-eight (62.3 percent) were in Class I, 13 (21.3 percent) were in Class II, seven (11.5 percent) were in Class III, and three (4.9 percent) were in Class IV.
(p
Discussion Since 1969, when Bloodwell and associates" popularized valve replacement without coronary perfusion, numerous reports have appeared attesting to the superiority or the dangers of coronary perfusion. No consensus has yet been reached for routine aortic valve replacement. However, the issue becomes even more critical in those patients with coexisting coronary artery disease, in whom prior myocardial infarction and marginally perfused myocardium limit normal tolerance to short periods of ischemia. It is not surprising, therefore, that most authors report substantial increases in mortality rate for patients with coronary artery disease who undergo aortic valve replacement. Having used a technique of aortic valve replacement prior to coronary artery bypass, Merin and associates" reported an operative mortality rate of 10 percent. Berndt and colleagues" described a 14 percent operative mortality rate and an II percent incidence of myocardial infarction. The use of coronary perfusion is not mentioned in these reports. Rossiter's group" reported a 14 percent operative mortality rate and a 21 percent incidence of myocardial infarction in 44 patients; they had performed aortic valve replacement at normothermic temperatures prior to coronary artery bypass in 39 of the patients and had used coronary perfusion in only nine. Using a similar technique, without coronary perfusion, Loop and as-
The Journal of Thoracic and Cardiovascular Surgery
sociates, in the largest series to date, reported a nine percent operative mortality rate, three times their rate for aortic valve replacement in patients without coronary artery disease. There was a 10 percent incidence of intraoperative myocardial infarction resulting in two deaths in 80 patients. In contrast, in our series there have been no operative deaths from myocardial ischemia and one myocardial infarction in 49 patients who have had intraoperative perfusion of the distal coronary arteries. Our over-all operative mortality rate of 6 percent does not differ significantly from our operative mortality of II percent for aortic valve replacement alone for patients of the same age group operated upon in the same institution over the same period of time. We readily admit that electrocardiographic and standard enzyme analysis generally underestimate the true incidence of myocardial infarction. All of the other reports, however, used similar criteria. Inter-institutional comparisons such as these are always fraught with hazards owing to a host of factors, not the least of which are differing patient populations and the many differing techniques utilized in the total care of the patient. In addition, the operative mortality in these procedures has fortunately been low, and the small series reported to date make statistical comparisons difficult. These caveats apply as well to intrainstitutional studies in which the patients have not been randomized. The patients operated upon by our earlier technique differ in no significant way in terms of age, sex, the character of their lesions, or catheterization findings from the patients operated upon more recently by the newer technique. Although the incidence of myocardial infarction appears to be significantly lower in the latter group, the patients occupy differing time frames and, therefore, our results can only be regarded as suggestive. The existence of significant coronary artery disease in approximately 50 percent of adults with aortic valve disease has been widely documented. 16. 17 although other authors find a much lower incidence in anginafree patients.!': 13 The role of coronary arteriography in the management of angina-free patients with aortic valve disease is thus unsettled and probably will remain so until the indications for coronary bypass surgery in the asymptomatic patient with coronary artery disease become clear. Loop.i Lacey.P and their co-workers recommended routine coronary arteriography in the presence of aortic valve disease, whereas Bonchek and associates!' recommended it only for those patients with angina. In this series, II patients (14 percent) were found to have significant coronary artery disease without angina, a percentage nearly identical to the in-
Volume 75 Number 6 June. 1978
Aortic valve replacement and coronary bypass
cidence recently reported by Loop's group. 2 Although there is as yet no proof that coronary bypass reduced the long-term morbidity or mortality in these patients, our concern for adequate oxygenation of the hypertrophied myocardium in aortic valve disease now leads us to recommend routine coronary arteriography, with coronary bypass for significant lesions, even in patients without angina. At present, this position can be justified only if coronary bypass surgery does not appreciably increase the morbidity or mortality of aortic valve replacement alone. With our present operative techniques, there have been no deaths and no myocardial infarctions in II angina-free patients with significant coronary artery disease. In addition, we feel that coronary bypass in these patients, if done prior to aortic valve replacement, provides protection to myocardium that might otherwise be compromised during aortic valve replacement.
4 Assad-Morell JL, Connolly DC, Brandenburg RO, Giuliani ER, Schattenberg RO, Pluth JR, Bamhorst DA, Wallace RB, Danielson GK: Aorta-coronary artery saphenous vein bypass grafts. Isolated and combined with other procedures. J THoRAc CARDIOVASC SURG 69:841850, 1975 5 Rossiter SJ, Hultgren HN, Kosek JC, Wuerftein RD, Angell WW: Myocardial damage in combined valvular and coronary bypass surgery. Circulation 52:Suppl 1:119-125, 1975 6 Berndt TB, Hancock EW, Shumway NE, Harrison DC: Aortic valve replacement with and without coronary artery bypass surgery. Circulation 50:967-971, 1974 7 Anderson RP, Bonchek LI, Wood JA, Chapman RP, Starr A: The safety of combined aortic valve replacement and coronary bypass grafting. Ann Thorac Surg 15:249255, 1973 8 Cooley DA, Dawson JT, Hallman GL, Sandiford FM, Wukasch DC, Garcia E, Hall RJ: Aortocoronary Saphenous Vein Bypass. Results in 1,492 patients with particular reference to patients with complicating features. Ann Thorac Surg 16:380-390, 1973 9 Merin G, Danielson GK, Wallace RB, Rutherford BD, Pluth JR: Combined one-stage coronary artery and valvular surgery. A clinical evaluation. Circulation 478:Suppl 3:173-176, 1973 IO Loop FD, Favaloro RG, Shirey EK, Groves LK, Effler DB: Surgery for combined valvular and coronary heart disease. JAMA 220:372-376, 1972 II Bonchek LI, Anderson RP, Rosch J: Should coronary arteriography be performed routinely before valve replacement? Am J Cardiol 31: 462-466, 1973 12 Lacey JP, Goodin RR, McMartin D, Masden R, Flowers N: Coronary atherosclerosis in valvular heart disease. Ann Thorac Surg 23:429-435, 1977 13 Paquay PA, Anderson G, Viefenthal H, Nordstrom L, Richman HG, Gobel FL: Chest pain as a predictor of coronary artery disease in patients with obstructive valve disease. Am J Cardiol 38:863-869, 1976 14 Starr A, Bonchek LI, Anderson RP, Wood JA, Chapman RD: Late complications of aortic valve replacement with cloth-covered, composite-seat prostheses. Ann Thorac Surg 19:289-300, 1975 15 Bloodwell RD, Kidd VN, Hallman GL, Burdette WJ, McMurtey MJ, Cooley DA: Cardiac valve replacement with coronary perfusion: clinical and laboratory observation, Prosthetic Heart Valves, LA Brewer, ed., Springfield, III, 1969, Charles C Thomas, Publisher 16 Linhart JW, de la Torre A, Ramsey HW, Wheat MW: The significance of coronary artery disease in aortic valve replacement. J THORAC CARDIOVASC SURG 55:811-814, 1968 17 Vieweg WJR, Tretheway DG, Alpert JS, Hagan AD: Distribution of coronary artery in patients with isolated aortic valve disease. Cardiovasc Surg 17:9-12, 1976
Summary In the absence of a randomized study, our experience and an examination of the reported experience of others leads us to recommend that all patients older than 40 years of age who have significant aortic valve disease, with or without angina, undergo routine coronary arteriography to delineate the extent and distribution of concomitant coronary artery disease. Significant coronary artery obstructions, even in angina-free patients, should be bypassed in such a manner that the distal coronary artery can be adequately perfused during aortic valve replacement. Coronary ostial perfusion in subjects with distal coronary artery obstruction has no proved advantages, but it is theoretically useful as an adjunct in perfusing proximal coronary branches. If all available resources are marshalled to provide maximum protection to the myocardium, the risk of aortic valve replacement in patients with coronary artery disease need be no greater than the risk of aortic valve replacement alone. REFERENCES Flemma RJ, Johnson WD, Lepley D, Auer JE, Tector AJ, Blitz J: Simultaneous valve replacement and aorta-tocoronary saphenous vein bypass. Ann Thorac Surg 12: 163-173, 1971 2 Loop FD, Phillips DF, Roy M, Taylor PC, Groves LK, Effler DB: Aortic valve replacement combined with myocardial revascularization. Circulation 55: 169-173, 1977 3 Rossiter SJ, Hultgren HN, Kosek JC, Wuerftein RD, Angel WW: Ischemic myocardial injury with aortic valve replacement and coronary bypass. Arch Surg 109:652658, 1974
869
Quentin Macmanus, M.D., Gary Grunkemeier, Ph.D., Louis Lambert, M.S., Charles Dietl, M.D., and Albert Starr, M.D., Portland, Ore.
Since the report of Flemma and associates' in 1971, several centers have described their experience with combined aortic valve replacement and aorta-coronary bypass surgery. 2-10 Operative mortality has varied from 4 to 15 percent, and postoperative myocardial infarction has occurred in 3 to 21 percent of patients. There is apparently little uniformity in the management of these patients. Debate has centered about the role of coronary arteriography in angina-free patients with aortic valve disease,": 11-13 the operative techniques best suited to ensure maximal myocardial protection,2-7 and the question of whether or not concomitant aorta-coronary bypass graft surgery influences the results of aortic valve replacernent.v !? In the hopes of moving toward some consensus on the proper approach to the treatment of these patients, From the Division of Cardiopulmonary Surgery, University of Oregon Health Sciences Center, Portland, Ore. 9720 I. Supported by U.S. Public Health Service Grant No. HL-16461. Received for publication Dec. 13, 1977.
we have examined our experience with concomitant aortic valve replacement and aorta-coronary bypass surgery.
Patients and methods From January, 1970, to January, 1977, 80 patients underwent isolated primary aortic valve replacement with concomitant aorta-coronary saphenous vein bypass grafting at S1. Vincent Hospital, Portland, Oregon. Clinical presentation varied from absence of symptoms in the presence of significant aortic valve gradients and coronary lesions (defined as greater than 50 percent stenosis) to Class IV* congestive heart failure with severe angina. Clinical and diagnostic data are listed in Table I. On the basis of clinical presentation, catheterization data, and operative findings, patients were categorized as having primarily aortic stenosis, aortic insufficiency, or mixed lesions. The nature of the lesion, as well as the etiology, can be found in Table II. The principal
Accepted for publication Jan. 13, 1978.
0022-5223/78/0675-0865$00.50/0 © 1978 The C. V. Mosby Co.
*New York Heart Association functional classification.
865
The Journal of Thoracic and Cardiovascular Surgery
866 Macmanus et al.
Table I. Clinical and diagnostic data No. of patients Male Female Age (yr.) Mean Range Severity of angina None Mild Moderate Severe Prior myocardial infarction N.Y.H.A. functional c1ass* Class I Class II Class III Class IV Catheterization datat Mean RAP (mm. Hg) RVP (mm. Hg) PAP (mm. Hg) Mean PAP (mm. Hg) LVP (mm. Hg) Aortic pressure (mm. Hg) Cardiac index (L./min./sq. M.) PVR (units) AS gradient (mm. Hg)
Table II. Nature and etiology of aortic valve lesions 80 61 19 63.1 44-81 12 14 36 18 10
23 (29)* 18 (22) 35 (44) 4 ( 5) 4.5 (50)t 37/6 (54) 35/14 (58) 22.1 (50) 183/18 (58) 137/66 (68) 2.8 (41) 2.0 69.6 (35)
Legend: N.Y.H.A., New York Heart Association. RAP, Right atrial pressure. RVP, Right ventricular pressure. PAP, Pulmonary arterial pressure. LVP, Left ventricular pressure. PVR, Pulmonary vascular resistance. AS, Aortic stenosis. 'Figures in parentheses indicate percentages. tFigures in parentheses indicate the number of values.
indication for aortic valve replacement can be found in Table III. A total of 120 aorta-coronary saphenous vein bypass grafts were placed at the time of aortic valve replacement. The distribution of vein grafts is listed in Table IV. Additionally, 20 patients underwent concomitant operations, the nature of which is listed in Table V.
Operative technique Our operative technique for aortic valve replacement comprises high-flow cardiopulmonary bypass with moderate (30 0 to 32 0 C.) systemic hypothermia. A vent in the apex of the left ventricle is routinely employed. The aortic root is opened transversely, and the incision is extended toward the noncoronary cusp if necessary for additional exposure. The pericardial sac is irrigated briefly with 4 0 C. Ringer's lactate. The diseased valve is sharply excised and sutures are placed in the aortic annulus. The coronary arteries are cannulated and the 0 0 heart is perfused with blood at 30 to 32 C. After a few minutes, the heart is electrically defibrillated and main-
Nature
Etiology
Lesion
No.
Lesion
No.
Aortic stenosis Aortic insufficiency Mixed
44 20 16
Bicuspid Rheumatic Atherosclerotic
28 II 41
Table III. Principal indication for aortic valve replacement Indication
No.
Angina and congestive heart failure Angina Angina, syncope, and congestive heart failure Free of angina Asymptomatic Congestive heart failure Syncope and congestive heart failure
36 17 16 I1 4 5 2
Table IV. Distribution of vein grafts Coronary artery
Right Left anterior descending Diagonal Obtuse marginal Total Avg. per patient
I
No. of vein grafts
43 51 2 24 120 I.5
tained in a beating state while the prosthesis is being sewn into place. Following valve replacement, the heart is fibrillated, the aortotomy is closed and all air is evacuated. The heart is then defibrillated and the catheter is removed from the left ventricle. The safety and efficacy of this technique have been widely documented. 14 The management of the associated vein grafts has been in a gradual state of evolution. Early in our experience with the combined operation, vein grafts were performed following aortic valve replacement, the distal anastomoses being done in the fibrillating heart and the proximal anastomoses in the beating heart with the aid of a partially occluding aortic clamp. Grafts were performed in sequence to ensure that the periods of ischemic arrest were kept as short as possible. This technique of replacing the aortic valve prior to performing vein graft anastomoses was used in 31 patients in this series. Although our operative results with this technique were satisfactory, 7 our continued desire to minimize the hypoxic insult to the often hypertrophied left
Volume 75 Number 6 June. 1978
Aortic valve replacement and coronary bypass
Table V. Associated surgical procedures Procedure
Right coronary endarterectomy Septal myotomy Ascending aortoplasty Left coronary endarterectomy Permanent pacemaker Resection of ventricular aneurysm Mitral commissurotomy Resection ofaneurysm ofascending aorta
I
867
No.
II 2
2 1
.~
-:::
60
Operation N • AVR • CA8G 80 o AVR only 196
"'t
1
I 1 1
M/F Mean Age 61/19 63.1 61.0 138/58
Mean Follow- up 2.6 Yr. 2.8 Yr.
20 0'-'-_-'-_-JL-_---'---_-----l_ _...L..._---'-_---' op 3 4 6
ventricular myocardium in subjects with aortic valve disease led us to modify our technique. We currently prefer to perform the grafts to the obtuse marginal and anterior descending arteries first, placing the proximal anastomoses high on the aortic root. The distal right anastomosis is performed next, the proximal anastomosis being delayed to improve exposure during valve replacement and to avoid kinking of the graft. Aortic valve replacement is then undertaken with the aortic cross-clamp below the ostia of the left-sided vein grafts to provide continuous myocardial perfusion. A perfusion catheter is placed in the vein graft on the right side, and the coronary ostia are perfused continuously as well during valve replacement. Perfusion cannulas are connected by a Y-connector and initial flow rates of 250 c.c. per minute are utilized; flow to each coronary bed, therefore, is determined only by distal resistance. Flow is adjusted up to 400 c.c. per minute as dictated by the appearance of the electrocardiogram; inadequate flow is demonstrated promptly by slowing of the heart rate or broadening of the QRS complex. Occasionally, severe aortic insufficiency or a short aortic root precludes this sequence of events, in which case the grafts to the left anterior and obtuse marginal vessels can be individually perfused following distal anastomosis; the proximal anastomosis is delayed for aortic valve replacement. This technique of placing one or all vein grafts prior to aortic valve replacement was employed in 49 patients in this series. Results Operative mortality rate. Five of 80 patients (6.3 percent) died from events temporally or causally related to the operative procedure. Two of the deaths were definitely due to intraoperative myocardial infarction. In both cases, coronary bypass followed aortic valve replacement (0.05 > P < 0.10). Another patient died of an arrhythmia 12 hours postoperatively. Findings at autopsy were unremarkable. One patient with cystic medial necrosis underwent ascending aortic aneurys-
Years
Fig. 1. Survival curves for patients having isolated aortic valve replacement (AVR) and for those having aortic valve replacement and coronary artery bypass grafting (A VR + CABG). Also shown is the expected survival curve for an age-matched and sex-matched normal population. Table VI. Causes of late death in 75
survivors of operation Cause
Congestive heart failure Myocardial infarction Thrombotic stenosis of theprosthesis Sudden, cause unknown Mycotic aneurysm Bacterial endocarditis Unrelated to cardiac disease Total
No.
2 1 I
2 I 1 2 10
morrhaphy and died on the fifth postoperative day from suture-line disruption. The fifth patient died 10 weeks after the operation from renal failure and sepsis that had resulted from gastric stress ulceration on the tenth postoperative day. Postoperative complications. Severe cardiac complications occurred in 16 patients (20.0 percent) and caused three of the deaths just described. Three patients had atrioventricular block necessitating a permanent pacemaker, three patients had ventricular fibrillation, and four patients had pulmonary edema. Myocardial infarction, defined as the appearance of new Q waves on the electrogram or persistent ST changes suggesting ischemia plus rises in LDH, SGOT, and CPK enzymes* above usual postoperative levels, occurred in six patients (7.5 percent), two of whom died. Five of the six myocardial infarctions occurred in patients who *LDH is lactic dehydrogenase; SGOT, serum glutamic oxaloacetic
transaminase; CPK, creatinine phosphokinase.
868
Macmanus et al.
had aortic valve replacement prior to vein bypass < 0.025). Late deaths. There were 10 late deaths (13.3 percent) among 75 operative survivors followed up a mean of 2.6 years. Causes of late death are listed in Table VI. A survival curve of operative survivors is shown in Fig. 1, along with the expected survival curve of an agematched and sex-matched normal population. Late functional results. All 65 long-term survivors were recently contacted by questionnaire and telephone regarding their current status. In case of ambiguity, the patient's private physician was contacted as well. Reliable information regarding angina was available in 63. Forty-one (65.1 percent) reported they never had angina, 13 (20.1 percent) had angina only with severe exertion, six others (9.5 percent) had angina with ordinary activity but felt less angina as a result of thier operation, and three patients (4.8 percent) were worse. Sixty-one patients returned sufficient information to categorize them according to the N. Y.H.A. classification for valvular disease. Thirty-eight (62.3 percent) were in Class I, 13 (21.3 percent) were in Class II, seven (11.5 percent) were in Class III, and three (4.9 percent) were in Class IV.
(p
Discussion Since 1969, when Bloodwell and associates" popularized valve replacement without coronary perfusion, numerous reports have appeared attesting to the superiority or the dangers of coronary perfusion. No consensus has yet been reached for routine aortic valve replacement. However, the issue becomes even more critical in those patients with coexisting coronary artery disease, in whom prior myocardial infarction and marginally perfused myocardium limit normal tolerance to short periods of ischemia. It is not surprising, therefore, that most authors report substantial increases in mortality rate for patients with coronary artery disease who undergo aortic valve replacement. Having used a technique of aortic valve replacement prior to coronary artery bypass, Merin and associates" reported an operative mortality rate of 10 percent. Berndt and colleagues" described a 14 percent operative mortality rate and an II percent incidence of myocardial infarction. The use of coronary perfusion is not mentioned in these reports. Rossiter's group" reported a 14 percent operative mortality rate and a 21 percent incidence of myocardial infarction in 44 patients; they had performed aortic valve replacement at normothermic temperatures prior to coronary artery bypass in 39 of the patients and had used coronary perfusion in only nine. Using a similar technique, without coronary perfusion, Loop and as-
The Journal of Thoracic and Cardiovascular Surgery
sociates, in the largest series to date, reported a nine percent operative mortality rate, three times their rate for aortic valve replacement in patients without coronary artery disease. There was a 10 percent incidence of intraoperative myocardial infarction resulting in two deaths in 80 patients. In contrast, in our series there have been no operative deaths from myocardial ischemia and one myocardial infarction in 49 patients who have had intraoperative perfusion of the distal coronary arteries. Our over-all operative mortality rate of 6 percent does not differ significantly from our operative mortality of II percent for aortic valve replacement alone for patients of the same age group operated upon in the same institution over the same period of time. We readily admit that electrocardiographic and standard enzyme analysis generally underestimate the true incidence of myocardial infarction. All of the other reports, however, used similar criteria. Inter-institutional comparisons such as these are always fraught with hazards owing to a host of factors, not the least of which are differing patient populations and the many differing techniques utilized in the total care of the patient. In addition, the operative mortality in these procedures has fortunately been low, and the small series reported to date make statistical comparisons difficult. These caveats apply as well to intrainstitutional studies in which the patients have not been randomized. The patients operated upon by our earlier technique differ in no significant way in terms of age, sex, the character of their lesions, or catheterization findings from the patients operated upon more recently by the newer technique. Although the incidence of myocardial infarction appears to be significantly lower in the latter group, the patients occupy differing time frames and, therefore, our results can only be regarded as suggestive. The existence of significant coronary artery disease in approximately 50 percent of adults with aortic valve disease has been widely documented. 16. 17 although other authors find a much lower incidence in anginafree patients.!': 13 The role of coronary arteriography in the management of angina-free patients with aortic valve disease is thus unsettled and probably will remain so until the indications for coronary bypass surgery in the asymptomatic patient with coronary artery disease become clear. Loop.i Lacey.P and their co-workers recommended routine coronary arteriography in the presence of aortic valve disease, whereas Bonchek and associates!' recommended it only for those patients with angina. In this series, II patients (14 percent) were found to have significant coronary artery disease without angina, a percentage nearly identical to the in-
Volume 75 Number 6 June. 1978
Aortic valve replacement and coronary bypass
cidence recently reported by Loop's group. 2 Although there is as yet no proof that coronary bypass reduced the long-term morbidity or mortality in these patients, our concern for adequate oxygenation of the hypertrophied myocardium in aortic valve disease now leads us to recommend routine coronary arteriography, with coronary bypass for significant lesions, even in patients without angina. At present, this position can be justified only if coronary bypass surgery does not appreciably increase the morbidity or mortality of aortic valve replacement alone. With our present operative techniques, there have been no deaths and no myocardial infarctions in II angina-free patients with significant coronary artery disease. In addition, we feel that coronary bypass in these patients, if done prior to aortic valve replacement, provides protection to myocardium that might otherwise be compromised during aortic valve replacement.
4 Assad-Morell JL, Connolly DC, Brandenburg RO, Giuliani ER, Schattenberg RO, Pluth JR, Bamhorst DA, Wallace RB, Danielson GK: Aorta-coronary artery saphenous vein bypass grafts. Isolated and combined with other procedures. J THoRAc CARDIOVASC SURG 69:841850, 1975 5 Rossiter SJ, Hultgren HN, Kosek JC, Wuerftein RD, Angell WW: Myocardial damage in combined valvular and coronary bypass surgery. Circulation 52:Suppl 1:119-125, 1975 6 Berndt TB, Hancock EW, Shumway NE, Harrison DC: Aortic valve replacement with and without coronary artery bypass surgery. Circulation 50:967-971, 1974 7 Anderson RP, Bonchek LI, Wood JA, Chapman RP, Starr A: The safety of combined aortic valve replacement and coronary bypass grafting. Ann Thorac Surg 15:249255, 1973 8 Cooley DA, Dawson JT, Hallman GL, Sandiford FM, Wukasch DC, Garcia E, Hall RJ: Aortocoronary Saphenous Vein Bypass. Results in 1,492 patients with particular reference to patients with complicating features. Ann Thorac Surg 16:380-390, 1973 9 Merin G, Danielson GK, Wallace RB, Rutherford BD, Pluth JR: Combined one-stage coronary artery and valvular surgery. A clinical evaluation. Circulation 478:Suppl 3:173-176, 1973 IO Loop FD, Favaloro RG, Shirey EK, Groves LK, Effler DB: Surgery for combined valvular and coronary heart disease. JAMA 220:372-376, 1972 II Bonchek LI, Anderson RP, Rosch J: Should coronary arteriography be performed routinely before valve replacement? Am J Cardiol 31: 462-466, 1973 12 Lacey JP, Goodin RR, McMartin D, Masden R, Flowers N: Coronary atherosclerosis in valvular heart disease. Ann Thorac Surg 23:429-435, 1977 13 Paquay PA, Anderson G, Viefenthal H, Nordstrom L, Richman HG, Gobel FL: Chest pain as a predictor of coronary artery disease in patients with obstructive valve disease. Am J Cardiol 38:863-869, 1976 14 Starr A, Bonchek LI, Anderson RP, Wood JA, Chapman RD: Late complications of aortic valve replacement with cloth-covered, composite-seat prostheses. Ann Thorac Surg 19:289-300, 1975 15 Bloodwell RD, Kidd VN, Hallman GL, Burdette WJ, McMurtey MJ, Cooley DA: Cardiac valve replacement with coronary perfusion: clinical and laboratory observation, Prosthetic Heart Valves, LA Brewer, ed., Springfield, III, 1969, Charles C Thomas, Publisher 16 Linhart JW, de la Torre A, Ramsey HW, Wheat MW: The significance of coronary artery disease in aortic valve replacement. J THORAC CARDIOVASC SURG 55:811-814, 1968 17 Vieweg WJR, Tretheway DG, Alpert JS, Hagan AD: Distribution of coronary artery in patients with isolated aortic valve disease. Cardiovasc Surg 17:9-12, 1976
Summary In the absence of a randomized study, our experience and an examination of the reported experience of others leads us to recommend that all patients older than 40 years of age who have significant aortic valve disease, with or without angina, undergo routine coronary arteriography to delineate the extent and distribution of concomitant coronary artery disease. Significant coronary artery obstructions, even in angina-free patients, should be bypassed in such a manner that the distal coronary artery can be adequately perfused during aortic valve replacement. Coronary ostial perfusion in subjects with distal coronary artery obstruction has no proved advantages, but it is theoretically useful as an adjunct in perfusing proximal coronary branches. If all available resources are marshalled to provide maximum protection to the myocardium, the risk of aortic valve replacement in patients with coronary artery disease need be no greater than the risk of aortic valve replacement alone. REFERENCES Flemma RJ, Johnson WD, Lepley D, Auer JE, Tector AJ, Blitz J: Simultaneous valve replacement and aorta-tocoronary saphenous vein bypass. Ann Thorac Surg 12: 163-173, 1971 2 Loop FD, Phillips DF, Roy M, Taylor PC, Groves LK, Effler DB: Aortic valve replacement combined with myocardial revascularization. Circulation 55: 169-173, 1977 3 Rossiter SJ, Hultgren HN, Kosek JC, Wuerftein RD, Angel WW: Ischemic myocardial injury with aortic valve replacement and coronary bypass. Arch Surg 109:652658, 1974
869