Abstract

BACKGROUND:

This experimental study was undertaken to determine whether using angiotensin-converting enzyme inhibitors during surgical revascularization of acutely ischemic myocardium would improve wall motion and limit infarct size.

METHODS:

Twenty pigs underwent 90 minutes of occlusion of the second and third diagonal arteries followed by 45 minutes of cardioplegic arrest and 180 minutes of reperfusion. In 10 animals, the angiotensin-converting enzyme inhibitor enalaprilat (0.05 mg/kg) was infused intravenously during coronary occlusion; 10 other animals received no angiotensin-converting enzyme inhibitors. Ischemic damage was assessed by the number of cardioversions required for ventricular tachycardia or fibrillation; wall motion scores using echocardiography (4=normal to -1=dyskinesia); and infarct size using histochemical staining. Epicardial coronary artery vasomotor function was assessed using standard organ chamber methodology.

RESULTS:

Enalaprilat-treated hearts had the least amount of ventricular irritability (0.84+/-0.24 versus 2.77+/-0.22 cardioversions; p < 0.01), the best recovery of wall motion score (3.20+/-0.15 versus 1.52+/-0.07; p < 0.0001), and the lowest infarct size (22.6%+/-1.4% versus 37.7%+/-3.0%; p < 0.001). Endothelium-independent relaxation was preserved in all hearts; however, endothelium-dependent relaxation was impaired in both groups.

CONCLUSIONS:

Angiotensin-converting enzyme inhibitors reduce myocardial damage during surgical revascularization of acutely ischemic myocardium.