The prognostic significance of angina pectoris experienced during the first month following acute myocardial infarction

Pathomorphology of postinfarction myocardial ischemia during atherosclerotic obstruction of coronary arteries

Pathomorphological criteria of early postinfarction angina included segmentary atherosclerotic obstruction of the upper segments of the coronary artery supplying the infarction area, recurrent acute myocardial infarction, maximum decrease in vascularization of the left posterior ventricular wall; and individual changes in angioarchitectonics of the heart promoting hibernation of the myocardium. Pathognomonic morphological criteria of silent postinfarction myocardial ischemia included diffuse extensive atherosclerotic obstruction of lower segments in the coronary artery supplying the infarction area and total hypervascularization of the myocardium, first acute myocardial infarction of the left ventricular anterior wall, and maximum decrease in vascularization of the anterior and posterior wall in the left ventricle. These coronary-myocardial relationships contribute to stunning of the myocardium. Zones of hypokinesia and akinesia were revealed in the left ventricle, which reflects the phenomenon of resting myocardium associated with isolation of heart angioarchitectonics.

Coronary smooth muscle reactivity to muscarinic stimulation after ischemia-reperfusion in porcine myocardial infarction

This study tested whether ischemia-reperfusion alters coronary smooth muscle reactivity to vasoconstrictor stimuli such as those elicited by an adventitial stimulation with methacholine. In vitro studies were performed to assess the reactivity of endothelium-denuded infarct-related coronary arteries to methacholine (n = 18). In addition, the vasoconstrictor effects of adventitial application of methacholine to left anterior descending (LAD) coronary artery was assessed in vivo in pigs submitted to 2 h of LAD occlusion followed by reperfusion (n = 12), LAD deendothelization (n = 11), or a sham operation (n = 6). Endothelial-dependent vasodilator capacity of infarct-related LAD was assessed by intracoronary injection of bradykinin (n = 13). In vitro, smooth muscle reactivity to methacholine was unaffected by ischemia-reperfusion. In vivo, baseline methacholine administration induced a transient and reversible drop in coronary blood flow (9.6 +/- 4.6 to 1.9 +/- 2.6 ml/min, P < 0.01), accompanied by severe left ventricular dysfunction. After ischemia-reperfusion, methacholine induced a prolonged and severe coronary blood flow drop (9.7 +/- 7.0 to 3.4 +/- 3.9 ml/min), with a significant delay in recovery (P < 0.001). Endothelial denudation mimics in part the effects of methacholine after ischemia-reperfusion, and intracoronary bradykinin confirmed the existence of endothelial dysfunction. Infarct-related epicardial coronary artery shows a delayed recovery after vasoconstrictor stimuli, because of appropriate smooth muscle reactivity and impairment of endothelial-dependent vasodilator capacity.