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Myocardial revascularization with saphenous vein grafts has produced excellent results in alleviating the symptoms of angina pectoris.4,13 Except for a small number of patients with advanced left ventricular dysfunction, these results have been uniform for most patients who suffer from obstructive major coronary disease. Women constitute approximately 10% of patients who undergo surgery. In most instances, their coronary arteries bear obstructive lesions similar to those of men. The overall results of saphenous vein grafts in women have usually been reported in combination with men and have been considered equally satisfactory.4,5 Our experience indicated that the results of this operation in women were less satisfactory than in men. We had a larger number of graft closures, technically more difficult coronary arteries to work on, and the eventual results in terms of effects on angina pectoris seemed less satisfactory. For these reasons we made a survey of our results in females after myocardial revascularization.
From May 1969 to August 1973, twenty-six women were operated upon. They were among 246 patients who received myocardial revascularization. In this period, four other females were also seen who were suffering from acute cardiac ischemia or so called preinfarction angina, and they are not included in this study. All patients were suffering from severe coronary artery disease and angina pectoris which was not responsive to conventional medical management including long acting nitrates (isosorbide trinitrate) and beta blocking agents (propranolol).
All patients underwent cardiac catheterization studies and hemodynamic evaluation prior to direct myocardial revascularization. Cardiac catheterization studies were done using Judkin's technique of percutaneous femoral artery approach. The left ventricular angiograms were obtained in right anterior oblique and left anterior oblique views. Right and left coronary arteriograms were recorded on 35 mm films with at least two views of each vessel.
The cardiac output was calculated by the Fick principle by analyzing blood samples from the pulmonary artery and from the descending aorta for oxygen content, and by measuring oxygen consumption by direct spirometry. Ejection fraction and volumes were calculated from biplane left ventricular angiograms using methods of Dodge et al.7 and by assuming the left ventricle as a thin walled ellipsoid.
An index of myocardial contractility (Vmax) was calculated from the left ventricular pressure curves obtained by a transducer catheter prior to left ventricular angiography. Isometric pressure-velocity calculations were made at 4 msec intervals from the developed left ventricular pressure and its rate of rise (dp/dt).l4 By extrapolation from the descending limb of pressure-velocity curve to zero pressure, an index, Vmax, was obtained as previously described.3 The left ventricular diastolic stiffness (Δp/Δv) was calculated by the methods of Diamond and Forrester.6
The surgical procedure was carried out under cardio-pulmonary bypass with normothermia and hemodilution perfusion technique. The left ventricle was drained by a sump catheter inserted through the right superior pulmonary vein. Postoperatively, in all patients for three consecutive days 12 lead electrocardiograms and serum enzyme studies were done in order to detect development of postoperative myocardial infarction.2 Postop erative cardiac catheterization studies were done in 15 females using methods similar to those described for preoperative studies.
For the purposes of comparison the clinical course of 51 consecutive male patients who were operated upon during 1972 was also analyzed. The results from postoperative cardiac catheterization studies of 12 of these 51 male patients were compared with those obtained in the female group. The statistical analysis of data was done by using Student's t-test comparing the observed data for the period of sampling.
CLINICAL COURSE: Fifteen of the 26 female patients had multiple coronary artery disease. Three patients died in the immediate postoperative period or late postoperatively (22 months after surgery), an incidence of 11.5%. Seven patients (26%) developed infarction in the course of surgery or in the early postoperative period (Table 1).
The 26 women and 51 men under study had a comparable extent of coronary artery vessel involvement (Table 1). The operative and late mortality in men, however, was only 2% and perioperative infarction rate was 6%.
HEMODYNAMIC DATA: A summary of complete hemodynamic data in 13 of the 15 women undergoing postoperative cardiac catheterization studies are shown in Table 2 and are compared with those in twelve men. Comparison of preoperative values of cardiac index, left ventricular end-diastolic pressure, Δp/Δv and left ventricular end-diastolic volume in men and women showed a significant difference. As shown in Table 2 overall, women had a better cardiac function preoperatively than men. However, after aorto coronary bypass surgery in most women there was a depression in each parameter of cardiac function with a significant increase in left ventricular end-diastolic pressure from 8±1 (SE) to 14±1 mmHg. (Figure 1). Also, Δp/Δv and left ventricular end-diastolic volume were increased (p < 0.05). The changes in cardiac index and ejection fraction were not significant, Figures 2 and and3.3. Postoperatively, in men, there was a statistically significant decrease in left ventricular end-diastolic pressure, from 23±2 to 13±1 mm Hg (p < 0.05). There was also a slight improvement in the mean values of other hemodynamic data, although these changes were not statistically significant (Figures 1,,22,,33 and Table 2).
Comparison of the progression of disease within the grafted and non-grafted native coronary vessels using methods described by Griffith10 showed that in the women only 2 of 15 vessels had developed proximal obstruction of the grafted artery with a patent graft. Three other women showed progression of coronary artery disease within other, non-grafted vessels. Thus, most major coronary vessels in these patients remained intact regardless of patency of the coronary bypass graft.
FOLLOW-UP: In the course of follow-up for 6 months to 3½ years, five of these 26 female patients (19%) have remained symptomatic with angina pectoris. All these patients are receiving the same or a larger amount of coronary vasodilator agents than preoperatively. Fifteen patients agreed to postoperative cardiac catheterization studies. Of the 27 coronary bypass grafts studied, only 14 were patent (50%) and the remaining could not be visualized at cardiac catheterization (Table 3).
The procedure of aorto-coronary bypass grafting can be done with low intra-operative morbidity and mortality.8,11 While the effects of this operation on diminishing angina pectoris have been excellent, its effects on improving cardiac function have been variable.3 In a recent report we objectively evaluated the effects of this operation on cardiac function. In a group of 21 patients including three females, there was an improvement in cardiac function in approximately 50% of all the patients studied. The results from the present studies indicate that less than 30% of women show an improvement in cardiac function after this procedure. Although in one-half the females studied postoperatively at least one of the vein grafts was closed, as shown in Figures 1, 2, and 3, the effects on hemodynamic parameters in patients with patent vein grafts were similar.
It was our impression that our female patients were not profiting from this operation to an extent comparable to the male population. This notion, added to the reports by various investigators indicating development of symptoms of coronary ischemia and myocardial infarction in females without disease of major coronary vessels, encouraged us to look more objectively at the results obtained in this group of patients.1,9,12 Our results indicate that overall, the effects of myocardial revascularization in female patients with chronic angina pectoris undergoing elective surgery with aorto-coronary bypass are inferior to the results in men. These findings included a slightly increased operative mortality and a two-fold increase in the incidence of perioperative myocardial infarction. Also, the number of women patients who had patent bypass grafts was small compared to men, and a large number of female patients remained symtomatic postoperatively regardless of the patency of coronary bypass grafts. These results indicate the possible role of other physiological factors producing angina pectoris in this group of patients. Previous studies have indicated factors such as disease within smaller coronary arteries or an increase in left ventricular diastolic volume, hence left ventricular wall tension, as playing a role in angina in females.9,2 In the present study, the preoperative left ventricular end-diastolic volume in women was significantly less than that of men and in contrast to males, most females showed an increase in this parameter after aorto-coronary bypass graft. It, therefore, could have played a role in persistence of symptoms of angina pectoris in these patients.
A number of previous reports dealing with patients suffering from clinical symptoms of ischemic heart disease without angiographic evidence of major coronary vessel involvement have hypothesized possible involvement of smaller coronary arteries in these patients.9,12 Disease within the smaller coronary vessels could have played a role in one of our patients who, despite a patent graft, died of acute myocardial infarction 22 months after coronary bypass surgery. This patient had a congenital aneurysm of the left anterior descending coronary artery which was not resected at the time of surgery. However, she had a cardiac arrest due to left ventricular dysrhythmia and myocardial infarction. A patent graft was visualized one month previously.
With these findings, we have concluded that in the female population, the indications for coronary artery surgery should include a thorough investigation of all factors which can produce angina pectoris.12 Mental disorders, patients' daily household activity and behavior, and adequacy of preoperative medical therapy should be evaluated along with the anatomy of the coronary arteries. While aorto-coronary bypass grafting in females is done for indications similar to those of men, its effects on angina pectoris or on the improvement of cardiac function are not similar. For these reasons, myocardial revascularization for women should be offered with a guarded outlook in terms of early and long-term results.
In the past four years, among 246 patients receiving coronary bypass grafts for stable coronary artery disease, there were 26 women (10%). Operative mortality was 7% (2/26), and one late death due to myocardial infarction occurred despite a patent coronary bypass graft. Intraoperative infarction rate was 26% (6% in men). Although preoperative cardiac pump and muscle function parameters in women (as compared with 52 men) were better (p < 0.10), postoperatively only 30% of them showed improvement in function as compared with 50% of men. At 6-46 month follow-ups, 81% of women were angina free in contrast to 94% of men. Early (four-month) graft patency rate was 50% as opposed to 80% in men. These results indicate that coronary artery disease in the female population shows an anatomic similarity to men; however, the results of surgical intervention with coronary revascularization are inferior to those in the male population.
This article has been reprinted from Cardiovascular Diseases: Bulletin of the Texas Heart Institute 1974;1:215–22.