Alteration of ventricular function during coronary artery surgery.

Abstract

The alteration in left and right ventricular (LV, RV) function during and immediately following coronary artery bypass surgery has been investigated in four studies, which are summarized here. In a total of 88 patients, anesthetized with morphine in oxygen (O2), basic hemodynamic monitoring and first pass radionuclide angiography were used to document changes in LV and RV function, LV compliance, and the effects of preload augmentation and afterload reduction on LV function. Two groups of patients with different physiologic responses were identified: those with preoperative ejection fractions (EF) greater than 0.50 and no dyssynergy (group I) and those with EF less than 0.50 or with dyssynergy (group II). In group I (n = 14), LV compliance was preserved following bypass (improved in four patients, no change in the remaining 10); normalized LV and RV stroke work were minimally depressed (70% of control); ejection fraction were minimally decreased (5%); and recovery of function occurred within 4 hours following bypass. In group II (n = 8), LV compliance decreased in all patients; RV and LV systolic function was moderately to severely depressed (40% of control); and recovery did not occur within 24 hours after bypass. In both groups, afterload reduction improved cardiac index, stroke volume index, and LV stroke work index after bypass, but the effects were more pronounced in group II patients. Preload augmentation with 1,500 ml of volume was not effective in either group when wedge pressure exceeded the normal ranges. Thus, significant ventricular dysfunction (RV and LV; systolic and diastolic) occurs during the immediate and prolonged post-bypass periods and can be predicted from the preoperative ejection fraction and degree of dyssynergy.