Operative risk in coronary revascularization of patients with ventricular dysfunction

Operative Risk in Coronary Revascularization

of

Patients with Ventricular Dysfunction I. K. Crosby, MB, BS, FRCS,” Kansas City, Missouri Duncan A. Killen, MB, Kansas City, Missouri Ali N. Shaikh, MD, Kansas City, Missouri B. D. McAllister, MD, Kansas City, Missouri William A. Reed, MD, Kansas City, Missouri

Direct myocardial revascularization is a well established procedure in the management of some aspects of advanced coronary artery disease. As the technics of coronary artery bypass grafting have evolved, many centers have been able to achieve hospital mortality figures that are quite low [l-5]. It is well established that very little morbidity and mortality are associated with revascularization of the coronary arterial tree in patients with few preoperative risk factors and good ventricular function. Features such as associated valvular disease, ventricular aneurysm, congestive heart failure, and cerebrovascular occlusive disease are reported as added risk factors in coronary artery surgery [1,2,5,6]. Poor left ventricular contractility has been classified as a significant risk factor and the role of revascularization in the presence of poor left ventricular contractility has not been clearly defined in terms of morbidity, mortality, and five year survival [6-8). In this series, patients with occlusive coronary artery disease were treated by direct revascularization technics regardless of any evidence of ventricular dysfunction on left ventricular cineangiography or elevation of left ventricular end diastolic pressure. The indication for surgery was the presence of severe angina that did not respond to medical management or the presence of From the Departments of Cardiovascular Surgery and Cardiology, St. Luke’s Hospital. and the University of Missouri, Kansas City, Missouri. Presented at the Twentv-Sixth Annual Meetina of the Southwestern Surgical Congress, Monterey, California, April 29 t: May 2, 1974. ‘Present address and address for reprint requests: Division of Thoracic and Cardiovascular Surgery, University of Virginia Medical Center, Charlottesville, Virginia 22901.

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unstable or preinfarction angina. Patients with profound congestive cardiac failure were treated medically. The majority of patients were diagnosed as having multiple vessel disease and every attempt was made at total revascularization of the myocardium by multiple bypass grafts. Direct revascularization procedures were combined with valvular surgery or ventricular aneurysmectomy whenever indicated. Material and Methods

From January 1971 through March 1974, 1,000 patients underwent simple revascularization procedures. Excluded from this group were patients who had valvular surgery or ventricular aneurysmectomy combined with revascularization. Critical evaluation of the available data in the first 252 patients who were operated on between January 1971 and April 1972 was undertaken using the preoperative functional classification of the New York Heart Association as well as coronary arteriography, left ventricular cineangiography, and left heart catheterization. In an attempt to determine the significance of left ventricular dysfunction in patients undergoing revascularization, patients were classified as having either a normal or an abnormal left ventricular cineangiogram and those with abnormal ones were arbitrarily graded from Class I to Class IV, paralleling the increasing dysfunction seen on the cineangiogram, or were finally classified as having a ventricular aneurysm. This arbitrary classification is represented in Figures 1 to 4 which depict the left ventricular end systolic volume typifying each class. The left ventricular end diastolic pressure both before and after angiography was noted in relation to the left ventricular angidgram. The

The American Journal of Surgery

Coronary Revascularlzatlon

Flgure 1. The end aystoik wlume shows there Is anterolaterat dyu&/nesla wtth some dlmlnutkn In contractkn. F&ure 2. In thk group there Is a larger end sy8totk volume wtth evldence of mitd generalized hypocontractlllfy. Figure 3. A more generalized hypocontractllly wtth a larger end sysfolk volume, and often evidence of dyskketk ventrkular contract/on. Figure 4. In grade IV the ventrkutar damage Is most severe and this Iikstratkn demonstratkg antero/atdyskinesta, era1 an old Inferkr myocard/al kfarctkn, and apical diiatkn in the end systotk volume Is typkal of this group.

sex distribution was 6.6 males to each female and most patients fell between the ages of thirty-five and sixtyfive years with a range of twenty-nine to seventy-six years. (Figure 5.) Because many patients had had coronary arteriography and left heart catheterization at other hospitals, complete information was not available in all of the initial 252 patients at the time of this review. A group of 159 consecutive patients were analyzed on the basis of pre- and postoperative electrocardiograms, coronary arteriograms, left ventricular cineangiograms, and the New York Heart Association classification. The over-all number of patients in this study has now increased to 1,000. The frequency of preoperative ventricular dysfunction and the over-all morbidity and mortality are essentially unchanged from those of the initial sixteen month experience. We therefore believe that the incidence of myocardial infarction, arrhythmia, and other complications is representative of our over-all experience. The surgical technic, which has not varied in any way because of the presence of preoperative left ventricular dysfunction, included a median sternotomy incision and simultaneous harvesting of the saphenous vein, usually from the thigh. A right atria1 and inferior vena caval line was used in conjunction with perfusion of the ascending aorta and a left ventricular vent at the apex as standard cannulation procedure for extracorporeal circulation. All patients were cooled to 30°C while the distal coronary artery anastomoses were being performed using a single period of aortic cross-clamping for each anastomosis. The patient was rewarmed while the proximal aortic anastomosis was being performed. All anastomoses were made while the patient was on total cardiopulmonary bypass. (Table I.) Blood flow was measured in the grafts prior to closure with a Biotronex flowmeter. The peri-

Volume 129, December 1974

cardium was left open and the mediastinum was drained with two polyethylene catheters connected to underwater seal and suction. Serial electrocardiography and enzyme studies for myocardial ischemia were routinely performed on postoperative days 1, 3, and 5 and after any unusual episode of chest pain. Postoperatively sublingual Isordile was given every four hours routinely throughout the hospital stay and was discontinued prior to the patient’s discharge. Selected patients received anticoagulants postoperatively. Initially the saphenous vein was used for all bypasses; since February 1972, the left internal mammary artery dissected as a single vessel, not as a pedicle, has fre-

PATIENT AGE

I

(IN 171 PATIENTS)

60

50

MALE

FEMALE

20

30

40

50

60

70

80

AGE INYEARS

Figure 5. Most patients treated surgically were between thirty-five and sixty-five years of age.

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Crosby et al

TABLE

Coronary

I

Revasculariration

Graft

Number of Patients

Deaths*

56 102 89 5 252

0 4 0 0 4

Single Double Triple Quadruple Total *The

TABLE

over-all

hospital

Number

II

in 252 Patients

mortality

of Vessels

was 1.6 per cent.

Involved* Number of Patients

Vessels

47 65 47

Single Triple Not available Total

... 159

*All were over 70 per cent stenotic.

TABLE

Operative

III

Procedures* Number of Patients

Graft Single Double Triple Quadruple

34 70 52 3 159 (342 grafts)

Total *Average,

TABLE IV

Grafts

2.2 grafts

per person.

Revasculariration Surgery of Coronary Arteries: Duration of Extracorporeal Circulation Duration of Extracorporeal Circulation

Number of Patients

Range (min)

Mean (min)

55 107 87 5

29-71 37-151 53-168 96-141

47.3 84 107.2 120

Single Double Triple Quadruple

TABLE V

Operative

Artery

Total

Measured

Range (ml/min)

Mean (ml/min)

177

155

15-240

102

203

187

20-300

100

157

139

16-240

96

15

3

20-90

61

Right coronary Left anterior descending Circumflex Marginal 1 Diagonal j Left internal mammary

748

Measurement

of Graft Flow

quently been used to bypass lesions in the anterior descending coronary artery. Endarterectomy was generally avoided by placing the bypass distal to the occlusive process unless the posterior descending branch of the right coronary artery did not become patent until the middle third of its course on the diaphragmatic surface of the ventricle. In these cases, mechanical endarterectomy of the distal main right coronary artery and its bifurcation was performed and a vein graft inserted into the distal arteriotomy site. During the same period, 107 other patients underwent valvular surgery and their results in terms of postoperative morbidity were compared with those in patients with revascularization.

Left ventricular cineangiograms indicated some degree of impaired left ventricular function in 57 ‘per cent (90) of the 159 consecutive patients as follows: Class I dysfunction, seventeen patients; Class II, thirty-six; Class III, fourteen; Class IV, seventeen; aneurysm, six. From a review of the left ventricular end diastolic pressures at rest, eighty patients or 50.3 per cent had elevated levels which ranged from 3 to 12 mm Hg and averaged 5.6 mm Hg. After angiography ninety-one or 57.3 per cent had elevation of the left ventricular end diastolic pressure which ranged from 13 to 39 mm Hg with an average of 9.3 mm Hg. The cineangiograms of the left ventricle were reviewed in the cardiology department at a separate time and without the knowledge of the elevated end diastolic pressure. The correlation between these two parameters in the assessment of left ventricular dysfunction is interesting. From the New York Heart Association classification 81 per cent of the 159 patients were either Class III (105 patients) or Class IV (36 patients) clinically. Of the remaining patients, 1 was Class I and 17 were Class 11. Tables II and III show that multiple bypass grafts were used whenever possible with an average of 2.2 grafts per patient. The duration of extracorporeal circulation in the first 252 consecutive cases was found to average forty-seven minutes for single grafts, eighty-four minutes for double grafts, 107 minutes for triple grafts, and 120 minutes for quadruple grafts. (Table IV.) Flow was measured in 484 of 549 consecutive bypass grafts [9]. Table V shows the range of graft flow found in bypass reconstruction to all three major coronary arteries and the mean flow achieved in each vessel. If the graft flows were ever less than 60 ml/min, 15 mg of papaverine was injected using a 25 gauge needle placed directly into the vein graft and the flow after this procedure gave an indication of the adequacy of the

The American Journal of Surgery

Coronary Revascularization

runoff and of both anastomoses. Table VI demonskates the results after papaverine injection. Myocardial Infarction. The strictest, most accurate criterion of perioperative myocardial infarction is the presence of a new or altered Q wave on the electrocardiogram. Enzyme elevations, the clinical occurrence of chest pain, and a decrease in cardiac output can support this diagnosis. However, when more than one recent myocardial infarction has occurred preoperatively, critical scrutiny of serial electrocardiograms can be diagnostically indefinite. Accordingly, patients in this series were grouped as having an absolutely incontrovertible myocardial infarction, a possible myocardial infarction, or no evidence of myocardial infarction. Thus, the criteria for the diagnosis of infarction in this series included the presence of new Q waves, concomitant ST segment shift and T wave inversion, enzyme elevation, and chest pain. Vectorcardiographic criteria were not used. Two per cent of the patients in this series (three patients) had a definite myocardial infarction and an additional 6 per cent (eleven patients) had a possible infarction. During the same sixteen month period, 107 patients who underwent valvular surgery had the same postoperative assessment and 2 per cent of these (two patients) had a definite infarction whereas 4 per cent (four patients) had a possible infarction. Pericarditis. Every patient who undergoes coronary revascularization has some degree of pericarditis in the postoperative period. The clinical diagnosis of pericarditis was made using the following criteria: pericardial rub, chest pain, and elevated ST segment on the electrocardiogram. Thirtythree per cent of the patients who had revascularization had pericarditis according to these criteria. The majority required no treatment at all. In a comparable group who had valvular surgery, 13 per cent had pericarditis. Although these criteria were selected arbitrarily and all cardiographic tracings were carefully scrutinized in the cardiology department, it is sometimes difficult to differentiate pericarditis from a possible myocardial infarction in a patient with a preoperative scar of the anterior and inferior wall in the presence of a deeper Q wave in leads III and AVF. Arrhythmia. Whether it is related to the routine use of aortic cross-clamping for the distal anastomoses, the routine use of moderate hypothermia, or the persistence of preoperative ventricular irritability, many patients exhibited cardiac irritability in the early postoperative phase. Intravenous infusion of Xylocaine@, 1 to 3 mg per minute,

Volme

128, December

1974

TABLE VI

Flow after lntraoperative Injection of Papaverine ~_. Mean Average Flow

Number

Before Papaverine

After Papaverine

Right coronary Left anterior

19

42

117

descending Circumflex Left internal

29 28

45 48

110

1

20

38

Artery

mammary

106

and intramuscular infusion of PronestyF, 560 mg every four hours, were used frequently during the postoperative period. Eighty-five per cent of patients had a normal sinus rhythm before surgery which was maintained throughout the hospital stay; 9 per cent of patients with normal sinus rhythm preoperatively had atria1 fibrillation in the early postoperative phase and had reconversion to normal sinus rhythm prior to discharge. Only one patient in this group required cardioversion. One per cent of patients with normal sinus rhythm had atria1 fibrillation postoperatively throughout their hospital stay. Two per cent of patients had atria1 fibrillation before surgery, cardioversion during surgery, but a return to atria1 fibrillation prior to discharge. Three per cent of patients had normal sinus rhythm preoperatively and in the early postoperative phase exhibited either ventricular fibrillation or ventricular tachycardia. All had reconversion to normal sinus rhythm. Mortality. Table VIII summarizes the ten deaths in the one thousand patients who had undergone revascularization. Comments

We believe the indication for coronary artery revascularization is still predominantly intractable chest pain; the presence of pain associated with arrhythmias and occlusive coronary artery disease, concomitant valvular disease, or subtotal occlusion of the left main coronary artery may influence the decision for earlier surgical management. The concept of total revascularization for all major obstructive lesions seems to have been important in achieving the low morbidity and mortality encountered in this present group of patients. The increase in the duration of extracorporeal circulation necessary to achieve this total revascularization has had little effect, if any, on hospital stay. From this review it seems that ventricular function has very little effect on operative mortality. The inci-

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Crosby et al

TABLE VII

Average SOOT Values Postoperatively

Myocardial infarction (vein grafts) Myocardial infarction (valves, etc) Possible myocardial infarction (vein grafts) Possible myocardial infarction (valves, etc) Pericarditis (vein grafts) Pericarditis (valves, etc)

Day 1

Day 3

Day 5

345 973

145 446

97 302

683

151

89

291 123 180

195 74 110

72 56 58

dence of myocardial infarction and pericarditis did not seem to be related to the degree of ventricular dysfunction. The routine measurement of graft flow at surgery has been helpful in assessing the adequacy of distal vessel runoff and of the anastomoses of each graft. The use of papaverine together with graft flow measurements has been helpful in eliminating the preventable technical causes of early graft occlusion. The routine elevation of enzyme levels after extracorporeal circulation is inconstant in magnitude and confusing when relating a single enzyme

TABLE VIII

Patient 1

2

Cause of Death in Ten Patients

Risk Factors 73 yr old, previous pneumonectomy Bronchial asthma

3

Six previous myocardial farctions and double Vineberg procedure

4

Severe congestive preoperatively Good risk patient

5

6

750

in-

failure

73 yr old, obese, diabetic; critical triple vessel disease

7 8

level to an individual patient. Table VII shows that, at best, there may be a trend that is characteristic of each clinical condition: patients with a definite myocardial infarction had very high enzyme levels which did not return to normal by the fifth postoperative day; patients with possible myocardial infarction had similarly high early levels but these seemed to return almost to normal by the fifth day; patients with pericarditis had elevated but not excessive levels which returned entirely to normal by the fifth day. At best, a single high serum glutamic oxalacetic transaminase or lactic dehydrogenase level postoperatively suggests myocardial &hernia. Ventricular dysfunction as evidenced by elevated left ventricular end diastolic pressure and left ventricular cineangiograms in itself is not a contraindication to revascularization of the coronary arterial tree. This series seems to show that despite this ventricular dysfunction, a remarkably low hospital mortality and morbidity can be achieved by total surgical revascularization. Postoperative re-study of the coronary circulation was not carried out routinely in the early postoperative

Good risk patient

Left Ventricular Cineangiogram

Operation

Cause of Death

Grade 1

Single graft

Grade 2

Single graft

Grade 3

Double graft

Grade 4

Double graft

Died in operating room, low cardiac output’ pulmonary hypertension Postoperative bleeding and asthma with pulmonary insufficiency, congestive failure; died 3 wk postoperatively Severed right mammary implant with sternal saw, acute myocardial infarction; had immediate double graft but died in operating room Died 6 days postoperatively of low cardiac out-

Grade 2

Double graft

Grade 2

Double graft

Grade 1

Double graft

Grade 1

Double graft

9

Grade 2

10

Grade 2

Left internal mammary artery and saphenous vein graft Left internal mammary artery and saphenous vein graft

put Sudden massive hemorrhage 4 hr after surgery, partial dehiscence of an aortic anastomosis, which was easily repaired; died of cerebral damage 4 days postoperatively Massive myocardial infarction, died 24 hr postoperatively Massive myocardial infarction 18 hr postoperatively; died Postoperative bleeding, probable inadequate replacement and hypotension -+ arrhythmia and death; autopsy showed no site ot bleeding Died 4 hr postoperatively; both grafts occluded Myocardial infarction and refractory arrhythmias, died 3 days postoperatively

The American Journal of Surgery

Coronary Revascularization

phase. Rather, elective re-study twelve months after revascularization is being undertaken. If the patient presents with recurrence of symptoms or a possible or definite myocardial infarction before this time has elapsed, he is re-studied at that time. Data concerning improvement in ventricular contractility, incidence of postrevascularization myocardial infarction and graft patency, and postoperative improvement in functional status are thus unavailable at this time. Summary

The initial sixteen month experience in patients undergoing simple revascularization of coronary arteries shows that 81 per cent of these patients were either Class III or Class IV on the basis of the New York Heart Association scale preoperatively; 57 per cent had some degree of ventricular dysfunction on left ventricular cineangiography, 50 per cent had elevated left ventricular graft dysfunction at rest, and 57 per cent had elevation post angiography. The hospital mortality was 1.6 per cent in the first 252 patients, and 2 per cent of the patients had a definite perioperative myocardial infarction and a further 6 per cent had a possible myocardial infarction. The total number of patients operated on between January 1971 and March 1974 now exceeds 1,000 with a total over-all hospital mortality of ten patients or 1 per cent. We believe that mortality and morbidity are essentially unchanged and that the flow study instances of myocardial infarction, pericarditis, and arrhyth-

Vohm. 129, December 1974

mia are representative of our over-all experience. Whenever significant valvular disease or ventricular aneurysm is associated with occlusive coronary artery disease, we believe that revascularization is necessary to achieve lower mortality and that ventricular dysfunction per se in patients undergoing revascularization is only a relative contraindication to revascularization. References 1. Barboriak JJ, Rimm A, Tristani, FE, Walker JR, Lepley, D Jr: Risk factors in patients undergoing aot-to-coronary bypass surgery. J Thorac Cardiovasc Surg. 64: 92, 1972. 2. Wilson HE, Dalton ML, Kiphart RJ, Allison WM: Increased safety of aorto-coronary artery bypass surgery with induced ventricular fibrillation to avotd anoxia. J Thorac Cardiovasc Surg 64: 193, 1972. 3. Johnson WD, Hoffman JF Jr, Flemma RJ, Tector AJ: Secondary surgical procedure for myocardtl revascularization. J Thorac Cardiovasc Surg 64: 523, 1972. 4. Edwards WA, Blakeley WR. Lewis CE: Technique of coronary bypass with autogenous arteries. J Thorac Cardiovasc Surg 65: 272, 1972. 5. Groves LK. Loop FD, Silver GM: Endarterectomy and a sup plement to coronary artery-saphenous vein bypass surgery. J Thorac Cardbvasc Surg 64: 514. 1972. 6. Urschel HC Jr, Maruf A, Razzuk MD, Wood RE, Paulson, DL: Distal CO* coronary artery endarterectomy and proximal vein bypass graft. Ann Thorac Surg 14: 10, 1972. 7. Adam M, Mitchel BF, Lambert CJ, Geisler GF: Long-term results with aorta to coronary artery bypass vein grafts. Ann Thorac Surg 14: 1, 1972. 6. Hammond GL, Poirier RA: Early and late results of direct coronary reconstructive surgery for angina. J Thorac Cardiovast Surg 65: 128, 1972. 9. Biir N, Kroncke GM, Dacumos GC Jr, Rowe GG, Young WP, Chopra PS, Foltz JD, Kahn DR: Vein graft flow and reactive hyperemia in the human heart. J Thorac Cardiovasc Surg 64: 856, 1972.

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