Myocardial revascularization with combined aortic and mitral valve replacements

J

THoRAc CARDIOVASC SURG

90:272-277, 1985

Myocardial revascularization with combined aortic and mitral valve replacements Although the results of coronary artery bypass grafting plus single aortic or mitral valvereplacement have been documented, the risk of myocardial revascularization with combined aortic and mitral valve replacement is not well dermed. We present a series of 33 consecutive patients undergoing myocardial revascularization with combined aortic and mitral valve replacement during a period of almost seven years. There were 21 men and 12 women with a mean age of 67 years. All patients had congestive heart failure, and 21 (64%) had angina pectoris. Mean New York Heart Association functional classification was 3.4; eight patients (24%) had ejection fractions less than 0.40, and 13 patients (41 %) had cardiac indices less than 2.0 L/min/m 2• Ali operations were performed with hypothermic crystalloid potassium cardioplegia. The number of coronary arteries grafted varied from one to four (mean, 1.7 grafts per patient), Four patients died while in the hospital (12.1 %). There were no perioperative myocardial infarctionS. At a follow-up of 2 to 80 months (mean 40.7 months), death had occurred in eight (27.6%) of the 29 hospital survivors. Actuarial survival rate at 72 months was 60.7%. Although no preoperative factorS predicted late death, early deaths were related significantly to severe mitral regurgitation, low ejection fraction, high New York Heart Association classification and extensive coronary artery disease (p < 0.05). Myocardial revascularization with combined aortic and mitral valve replacement can be performed with an acceptable early mortality rate but with an appreciable late mortality rate.

Cary W. Akins, M.D., Mortimer J. Buckley, M.D., Willard M. Daggett, M.D., Alan D. Hilgenberg, M.D., and W. Gerald Austen, M.D., Boston, Mass.

h e prevalence of coronary artery occlusive disease in our society and the rapid growth of coronary artery bypass grafting to successfully treat ischemic heart disease have led to the combination of myocardial revascularization with numerous other cardiac surgical procedures. The risks of myocardial revascularization performed with isolated aortic or mitral valve replacement have been well documented, I-I I although the results of coronary artery bypass grafting with combined aortic and mitral valve replacement have been reported for only small numbers of patients.v" 12-24 We reviewed the records of 33 consecutive patients having coronary artery bypass grafting with combined aortic and mitral valve replacement in an attempt to From the Department of Surgery, Massachusetts General Hospital, Boston, Mass, Received for publication Oct. 15, 1984. Accepted for publication Nov. 15, 1984. Address for reprints: Cary W, Akins, M.D., Department of Surgery Massachusetts General Hospital, 32 Fruit St., Boston, Mass. 02114.

272

define some of the risks associated with this combination of operations. Patients and methods Between May, 1977, and March, 1984, 245 patients had combined aortic and mitral valve replacement at the Massachusetts General Hospital. Of the 245 patients, 33 patients also had myocardial revascularization. These 33 consecutive patients constitute the study group. Twenty-one men and 12 women composed the series. The clinical characteristics of these patients are summarized in Table I. Patients' ages ranged from 50 to 79 years with men having a mean age of 64.7 years and women 70.1 years. Fifteen (45%) of the patients were 70 years of age or older. All 33 patients had symptoms of congestive heart failure, and 21 (64%) had angina pectoris. Seven patients (21%) had a history of a prior myocardial infarction. Only one patient had a prior cardiac operation-a mitral commissurotomy. On preoperative electrocardiograms 16 (48%) of the patients had evidence of left ventricular hypertrophy, and 16 patients (48%) had conduction abnormalities.

Volume 90 Number 2

Revascularization plus valve replacement

August, 1985

Table I. Clinical patient characteristics (n = 33) No. of patients

%

21 12

64

Sex Male Female Age (mean = 66.7 yr) 50-59 60-69 70-79 Symptoms Congestive heart failure A ngina pectoris NYHA class (mean = 3.4)

II III IV Valvular Aortic Aortic Mitral Mitral

7

II 15

21 33 45

33 21

100

I

3 55 42

18 14 pathology stenosis regurgitation stenosis regurgitation

Table II. Preoperative catheterization findings (n = 32) No. of patienrs

36

25 14 19 21

64

76 42 58

273

LVEDP (mm Hg, mean

I~

= 16.3) 15

-S 12 13-20

8

21-30 31-40 Ejection fraction (mean = 0.51) 0.20-0.29 0.30-0.39 0.40-0.49 2"0.50 Cardiac index (L/min/m', mean 1.0-1.9 2.0-2.9 3.0-3.9

7 2

I 7 6 18

= 2.2)

13 15

4

47 25 22

6 3 22 19 56 41 47 12

t rgrnd: LVEDP. Len ventricular end-diastolic pressure.

64

Legend: /VVHA. New York Heart Association.

Table

m. Prosthetic valves inserted Type

All patients had preoperative cardiac catheterization, the findings of which were available for 32 patients. Pertinent results from these catheterizations are listed in Table II. In 17 patients (52%) left ventricular enddiastolic pressure was 12 mm Hg or more with a mean left ventricular end-diastolic pressure of 16.3 mm Hg. The mean ejection fraction was 0.51; eight patients (24%) had ejection fractions less than 0.40. The mean cardiac index was 2.2; 13 patients (41%) had a cardiac index less than 2.0 L/min/m 2• All patients underwent operation with cardiopulmonary bypass utilizing a bubble oxygenator. Hypothermic crystalloid potassium cardioplegia was utilized as the method of myocardial preservation in all patients. Systemic hypothermia from 250 to 280 C was additionally utilized in 17 patients; in 16 patients the temperature was reduced to 20 0 to 220 C. All patients received hypothermic potassium cardioplegic solution either manually or mechanically injected directly into both coronary arteries until there was cessation of mechanical and electrical activity in the myocardium. The solution was then reinstilled at intervals of 20 to 30 minutes or more frequently if there was evidence of return of electromechanical activity. All patients underwent coronary artery bypass grafting with reversed saphenous veins, with an average of 1.7 grafts per patient. Seventeen patients had one coronary artery bypassed, 11 patients had two, four patients had three, and one patient had four. Proximal

Porcine Carpentier-Edwards Hancock Mechanical Bjork-Shiley Starr-Edwards Hall-Medtronic

Aortic

Mitral

14 13

14 II

2 2 2

4 2 2

Tricuspid

vein-to-aorta anastomoses were performed prior to the institution of cardiopulmonary bypass and usually prior to atrial cannulation. All patients had aortic and mitral valve replacement with either mechanical or porcine prostheses. The distribution of prosthetic valves utilized is listed in Table III. In addition, one patient had insertion of a tricuspid valve and closure of an atrial septal defect, and a second patient had a left ventricular myectomy for hypertrophic subaortic stenosis. The sequence in which the various portions of the operation were performed varied somewhat from surgeon to surgeon, but most patients had construction of their distal coronary anastomoses initially followed by replacement of their valves after the bypasses had been completed. In most instances the aorta was opened and the native coronary vessels directly cannulated for the infusion of cardioplegic solution. The aortic valve was excised and sized before the distal anastomoses were begun. As each distal anastomosis was completed, hypothermic potassium cardioplegic solution was

274

The Journal of Thoracic and Cardiovascular Surgery

Akins et al.

100,,----------------,

90

Table IV. Predictors of hospital death Factor

80

Severe mitral regurgitation Ejection fraction sO.35 NYHA Class IV· Triple-vessel coronary artery disease

70 60

p Value

0.003 0.02 0.03 0.04

Legend: NYHA, New York Heart Association.

50 40 30 20 10

o '----=------:'--=--:='-:----:::'-:=--c:'-=-----,-L:~'_:__='_"::----=_=__---' 8

16 24 32 40 48 56 64 72

POSTOPERATIVE INTERVAL (months) Fig. 1. Actuarial survival rate of patients having myocardial revascularization with combined aortic and mitral valve replacement.

injected into the individual saphenous grafts and the native coronary arteries through the open aortotomy at intervals of 20 to 30 minutes. Serial electrocardiograms and cardiac enzyme determinations were performed for all patients for 3 days postoperatively. A perioperative myocardial infarction was diagnosed if there were either new Q waves on the electrocardiogram or elevations of the myocardial fraction of creatine kinase above 40 IV. Late follow-up was conducted by a trained research nurse who contacted either the patient directly or the patient's physician if the patient had been seen within I month. Preoperative variables including gender, age, New York Heart Association (NYHA) functional classification, left ventricular end-diastolic pressure, ejection fraction, cardiac index, extent of coronary artery disease, and nature of the valvular lesions were assessed to look for predictors of early and late death. Chi square, Fisher, and Kruskal-Wallis tests were used where appropriate (all univariate forms of analysis). Actuarial survival for the entire series was computed by standard life-table analysis. Results For the 33 patients in the series, aortic cross-clamp times varied from 70 to 205 minutes with a mean aortic cross-clamp time of 97 minutes and a median crossclamp time of 92 minutes. Twenty-six of these patients (79%) received some

type of inotropic support in the postoperative period. In the majority of patients this was low-dose dopamine infusion of less than 3.0 ~g/kg/min. In seven patients (21 %) an intra-aortic balloon pump was utilized for a period varying from 1 to 5 days (mean 2.9 days). In no patient was a perioperative myocardial infarction diagnosed. Important postoperative complications occurred in eight patients: two underwent reexploration to control bleeding, two had wound infections, and one each had a cerebrovascular accident, a ventricular fibrillation arrest, a pulmonary embolus, and requirement for insertion of a permanent pacemaker. For the entire group of 33 patients, four deaths occurred in the hospital (12.1%). One patient died on the first postoperative day of an uncontrolled coagulopathy, a second patient died on the twenty-first postoperative day of progressive renal failure, a third death occurred as a result of sepsis on the twenty-seventh postoperative day, and the fourth patient died on the fifty-third postoperative day of progressive respiratory failure. Long-term follow-up was achieved in all patients at an interval of 2 to 80 months with a mean follow-up of 40.7 months. There were eight deaths during this interval in the 29 hospital survivors, which resulted in a late mortality rate of 27.6%. Causes of late deaths that occurred between 2 and 74 months postoperatively (mean 21.9 months) were arrhythmias in three, infection or sepsis in three, cerebrovascular accident in one, and peripheral emboli in one. Significant late complications occurred in seven patients, three of whom required therapy for recurrent congestive heart failure. Two patients have undergone successful repeat cardiac operation, repair of a degenerating mitral porcine prosthesis in one patient, and repair of an aortic paravalvular leak plus additional coronary artery bypass grafting in a second patient. One patient had a pulmonary embolus, and another required a below-the-knee amputation because of progressive ischemia secondary to diabetes mellitus. The remaining 14 patients remain active and symptomatically markedly improved.

Volume 90 Number 2 August, 1985

While no preoperative factors significantly predicted late death, deaths occurring in the hospital were significantly related to severe mitral regurgitation, ejection fraction of 0.35 or less, NYHA Class IV, and triplevessel coronary artery disease (Table IV). Actuarial survival for the entire patient population is depicted in Fig. 1. At 72 months, actuarial survival rate was 60.7% ± 9.5%.

Discussion Various large series in the literature have documented the operative risk of myocardial revascularization when combined with isolated aortic valve replacement 1-8, II to range from 1.9% to 8.9% (mean 6.0% for series cited) and when combined with isolated mitral valve replacement6,8-IO to range from 3.0% to 14.8% (mean 9.5% for series cited). In contrast, review of the literature has uncovered only small series-" 12-24 that have reported the combination of myocardial revascularization and combined aortic and mitral valve replacement (Table V). The largest group comes from a report by Stephenson and associates, 12 which included 146 patients who underwent combined aortic and mitral valve replacement, 19 of whom had associated coronary artery bypass grafting. Additional information provided by Stephenson indicated that two (10.5%) of the 19 patients died while in the hospital. In a complete follow-up of their 17 hospital survivors at a mean follow-up period of 36.8 months there were six additional deaths resulting in a late mortality rate of 35.3%. The hospital mortality rate of 12.1% reported in our series compares with that of Stephenson and colleagues" whereas the long-term mortality rate at a longer follow-up interval of 40.7 months is somewhat less at 27.6%. Actuarial survival for our group of patients was 60.7% at 72 months. Thus, although the operative mortality rate for this rather extensive combined operation is acceptable, the longterm mortality rate is appreciable. The usefulness of hypothermic potassium cardioplegia has been well documented for many types of cardiovascular procedures, particularly for operations during which prolonged aortic occlusion times are necessary. We have previously reported the use of hypothermic potassium cardioplegia for the somewhat longer aortic occlusion times that are required during the operations for ascending aortic aneurysms." Other authors have reported similar results with other combined cardiovascular procedures that require extended periods of aortic occlusion. 16, 26 The use of this technique of myocardial preservation obviously allows one to

Revascularization plus valve replacement

275

Table V. Series containing patients undergoing myocardial revascularization with combined aortic and mitral valve replacement Series

No. of patients

Early death

Stephenson" (1984) Okies 13 (1974) Hatcher!' (1983) Assad-Morell" (1975) Catinella" (1982) Jolly" (1981) Lundell" (1978) Pluth!9 (1975) Heck" (1979) Fjeld2! (1977) Wisor!" (1980) Reed' (1983) Callard" (1976) Flemma" (1971) Gallo" (1981)

19 9 7 5 5 4 4 4 3 3 2 2 1 1 1

2 (10.5%) 4 (44.4%) 0

NA

Total'

48

9 (18.8%)

NA NA

1(25.0%)

NA 1 (25.0%)

NA 0

NA NA 0 1 (100%)

Legend: NA. Not available. 'Totals only for series reporting early mortality.

perform the combined bypass grafting and valve replacement in a quiet, unobstructed field on a flaccid heart with the expectation that ventricular function will not be unduly compromised. Although the hospital mortality rate of this group of patients is fairly low, there was a relatively high incidence of utilization of pressor agents (admittedly in most cases, low-dose dopamine) and also of intra-aortic balloon pumping. All of the patients who required intra-aortic balloon pumping had aortic cross-clamp times considerably in excess of the mean cross-clamp time for the group as a whole. In addition, all but one patient had cardiac indices below the mean for the group. Also, of those who required intra-aortic balloon pumping, the average number of bypass grafts per patient was 2.3, whereas for the patients who did not require intra-aortic balloon pumping, the average number of grafts per patient was 1.5. Thus, although none of the patients had evidence of a perioperative myocardial infarction, our technique of myocardial preservation is certainly not perfect. Two of the four patients who died in the hospital did have intra-aortic balloon pumping during the early part of their postoperative course, and of the eight patients dying later, only two had required intra-aortic balloon pumping at the time of operation. We continue to advocate the early application of intra-aortic balloon pumping for patients who demonstrate significant ventricular dysfunction following large

2 7 6 Akins et aJ.

combined cardiac procedures, even in the absence of acute ischemia. In an attempt to define the subgroups of patients who constitute the higher risk categories for this combined procedure, our univariate analyses have defined four statistically significant predictors that are associated with a higher incidence of hospital mortality. They include severe mitral regurgitation, diminished ejection fraction, high NYHA classification, and extensive coronary artery disease. Poor ventricular function in association with mitral regurgitation has been identified as a strong predictor of poor survival for isolated mitral valve replacement. 27 In addition, for patients having mitral valve replacement and myocardial revascularization, the highest operative risk is associated with mitral regurgitation secondary to ischemic heart disease when compared with either mitral stenosis or mitral regurgitation of rheumatic origin." Of the valvular lesions, then, mitral regurgitation, particularly when it is a sequel of coronary artery disease, is as accurate a predictor of early death in this combined valvular and myocardial revascularization procedure as it is for isolated mitral valve replacement combined with coronary artery grafting. We gratefully acknowledge the assistance of John B. Newell, B.A., Director, Cardiac Computer Center, Massachusetts General Hospital, for his assistance in the statistical assessment of the data in this report, Diane Carroll, R.N., B.S., for her assistance in data accumulation, and Rosemary Noren for her assistance in the preparation of this manuscript.

REFERENCES

2

3

4

5

Craver JM, Jones EL, Hatcher CR: Concomitant aortic valve replacement and myocardial revascularization. Ann Surg 185:713-716, 1977 Loop FD, Phillips DF, Roy M, Taylor PC, Groves LK, Effler DB: Aortic valve replacement combined with myocardial revascularization. Late clinical results and survival of surgically-treated aortic valve patients with and without coronary artery disease. Circulation 55: 169-173, 1977 Macmanus Q, Grunkemeier G, Lambert L, Dietl C, Starr A: Aortic valve replacement and aorta-coronary bypass surgery. Results with perfusion of proximal and distal coronary arteries. J THORAC CARDIOVASC SURG 75:865869, 1978 Miller DC, Stinson EB, Oyer PE, Rossiter SJ, Reitz BA, Shumway NE: Surgical implications and results of combined aortic valve replacement and myocardial revascularization. Am J Cardiol 43:494-501, 1979 Richardson JW, Kouchoukos NT, Wright JO, Karp RB: Combined aortic valve replacement and myocardial revas-

The Journal of Thoracic and Cardiovascular Surgery

cularization. Results on 220 patients. Circulation 59:7581, 1979 6 Wisoff BG, Fogel R, Weisz D, Garvey J, Hamby R: Combined valve and coronary artery surgery. Ann Thorac Surg 29:440-443, 1980 7 Nunley DL, Grunkemeier GL, Starr A: Aortic valve replacement with coronary bypass grafting. J THORAC CARDIOVASC SURG 85:705-711,1983 8 Reed GE, Sanondos GM, Pooley RW, Moggio RA, McClung JA, Praeger PI: Results of combined valvular and myocardial revascularization operations. J THORAC CARDIOVASC SURG 85:422-426, 1983 9 Kay JH, Mendez M, Zubiate P, Yokoyama T, Vanstrom N, Gharavi M: Long-term results of operations for mitral insufficiency secondary to coronary artery disease. Cardiovase Clin 12:75-80, 1981 10 DiSesa VJ, Cohn LH, Collin JJ, Koster JK, vanDevanter S: Determinants of operative survival following combined mitral valve replacement and coronary revascularization. Ann Thorac Surg 34:482-489, 1982 II Kouchoukos NT, Lell WA, Rogers WJ: Combined aortic valve replacement and myocardial revascularization. Ann Surg 197:721-727, 1983 12 Stephenson LW, Edie RN, Harken AH, Edmunds LH: Combined aortic and mitral valve replacement. Changes in practice and prognosis. Circulation 69:640-644, 1984 13 Okies JE, Phillips SJ, Chaitman BR, Starr A: Technical consideration in multiple valve and coronary artery surgery. J THORAC CARDIOVASC SURG 67:762-769, 1974 14 Hatcher CR, Craver JM, Jones EL, Bone DK, Guyton RA: The porcine prosthesis. Am Surg 49:6-10, 1983 15 Assad-Morell JL, Connolly DC, Brandenburg RO, Giuliani ER, Schattenberg TT, Pluth JR, Barnhorst DA, Wallace RB, Danielson GK: Aorta--eoronary artery saphenous vein bypass grafts. Isolated and combined with other procedures. J THoRAc CARDIOVASC SURG 69:841850, 1975 16 Catinella FP, Cunningham IN, Adams PX, Snively SL, Gross RI, Spencer FC: Myocardial protection with cold potassium cardioplegia during prolonged aortic crossclamping. Ann Thorac Surg 33:228-233, 1982 17 Jolly WW, Isch JH, Shumacker HB: Cardiac surgery in the elderly. Cardiovasc Clin 12: 195-210, 1981 18 Lundell DC, Laks H, Geha AS, Khachane VB, Hammond GL: The importance of myocardial protection in combined aortic valve replacement and myocardial revascularization. Ann Thorac Surg 28:501-508, 1978 19 Pluth JR, Broadbent JC, Barnhorst DA, Danielson GK: Aortic and mitral valve replacement with cloth-covered Braunwald-Cutter prosthesis. Ann Thorac Surg 20:239248, 1975 20 Heck HA, Wright CB, Doty DB, Rossi NP, Ehrenhaft JL: Combined multiple valve procedures. A 5-year experience with 125 patients. Ann Thorac Surg 27:320-327, 1979 21 Fjeld NB, Semb G, Sivertssen E, Skatun J: Aorto-

Volume 90 Number 2 August, 1985

coronary vein bypass and valvular surgery. Scand J Thorac Cardiovasc Surg 11:211-215, 1977 22 Callard GM, F1ege JB, Todd JC: Combined valvular and coronary artery surgery. Ann Thorac Surg 22:338-342, 1976 23 F1emma RJ, Johnson WD, Lepley D, Auer JE, Tector AJ, Blitz J: Simultaneous valve replacement and aorta to coronary saphenous vein bypass. Ann Thorac Surg 12:163-170, 1971 24 Gallo n, Ruiz B, Carrion MF, Gutierrez JA, Vega JL, Duran CMG: Heart valve replacement with the Hancock bioprosthesis. A 6-year review. Ann Thorac Surg 31:444449, 1981

Revascularization plus valve replacement 2 7 7

25 Akins CW, Buckley MJ, Austen WG, Daggett WM, Levine FH: Myocardial protection with hypothermia and potassium cardioplegia during operation for ascending aortic aneurysms. J THORAC CARDIOVASC SURG 79:700704, 1980 26 Weisel RD, Hoy FBY, Baird RJ, Burns RJ, Mickle DAG, Ivanov J, Madonik MM, McLaughlin PR: Improved myocardial protection during a prolonged cross-clamp period. Ann Thorac Surg 36:664-674, 1983 27 Radford MJ, Johnson RA, Buckley MJ, Daggett WM, Leinbach RC, Gold HK: Survival following mitral valve replacement for mitral regurgitation due to coronary artery disease. Circulation 60:Suppl 1:39-47, 1979