Comparative effects of ischemia and hypoxemia on left ventricular systolic and diastolic function in humans

Abstract

Background. During the initial phase of an ischemic insult, left ventricular (LV) performance depends on the complex interaction between oxygen deprivation, vascular turgor, and accumulation of metabolites. In experimental preparations, low-flow ischemia decreases systolic shortening and increases diastolic LV distensibility, whereas pacing-induced ischemia or hypoxic perfusion produces smaller decreases in systolic shortening but decreases LV diastolic distensibility. The purpose of this study was to investigate the different effects of low-flow ischemia, pacing-induced ischemia, and hypoxemic perfusion on LV performance in humans. Methods and Results. In 20 patients with a significant stenosis in the left anterior descending coronary artery, micromanometer-tip LV pressure recordings (n=20), LV angiography (n=18), and coronary sinus blood sampling (n=11) were obtained at rest and during the following conditions: pacing-induced ischemia (PI) (n=11), low-flow ischemia of balloon coronary occlusion (CO) (n=20), and hypoxemia induced by balloon coronary occlusion with hypoxemic perfusion distal to the occlusion (CO+P) (n=11). LV stroke work index fell from 75±17 g · m at rest to 43±14 g · m at the end of CO (n=18; P