Ventricular function at rest, during leg raising and physical exercise before and after aortocoronary bypass surgery

Abstract

In nine patients with coronary heart disease contractility indexes during isovolumic contraction and during the ejection phase were measured simultaneously, using an angiographic catheter-tip manometer. Regional wall motion at rest, after leg raising and during physical exercise (bicycle ergometer) was analyzed using the hemiaxis method. Five weeks after aortocoronary bypass surgery these examinations were repeated. Preoperatively left ventricular end-diastolic pressure increased from 21 to 37 mm Hg after leg raising. The velocity of mean circumferential fiber shortening (VCF) and of regional shortening in the anterior wall decreased significantly. All patients discontinued physical exercise due to angina pectoris. Left ventricular end-diastolic pressure increased from 21 to 39 mm Hg during exercise. Large hypokinetic and akinetic areas developed, especially in the anterior wall. Velocity of fiber shortening of the anterior wall decreased from 1.43 to 0.76/sec. End-diastolic volume remained unchanged, but end-systolic volume increased significantly. In six patients with patent grafts surgery had a beneficial effect. Angiograms at rest revealed no significant postoperative changes; however, after leg raising and physical exercise, ventricular function was greatly improved over the preoperative performance. Velocity of fiber shortening in the anterior wall increased significantly from 0.76 to 2.56/sec, mean VCF from 1.11 to 2.12 circumferences/sec, maximal rate of rise of left ventricular pressure from 2,302 to 4,280 mm Hg/sec and peak velocity of contractile elements (Vpm) from 27.8 to 55.7/sec. The mean functional improvement in individual wall segments was 500 percent. Ejection fraction increased from 54 percent to 76 percent. End-diastolic volume remained unchanged while end-systolic volume decreased from 67 to 33 ml/1.73 m 2 ( P < 0.002). In three patients occlusion of the bypass graft or myocardial infarction occurred intraoperatively. Their postoperative findings at rest and during exercise were unchanged from the preoperative values. After successful bypass surgery ventricular function at rest did not change, but during exercise, a marked improvement in overall and in regional ventricular function was found.