Regional electrical activation and mechanical function in the partially ischemic left ventricle of dogs

The American Journal of Physiology
T DelhaasR S Reneman

Abstract

During normoxia, asynchronous electrical activation of the left ventricle significantly affects regional mechanical performance. Regional fiber strain and external work during the ejection phase are found to be lower in early-activated than in late-activated regions. Because electrical activation is known to be delayed during ischemia, the present study was designed to investigate the influence of this electrical asynchrony on regional fiber strain, if any, during moderate and severe myocardial ischemia. Regional electrical activation time (t(ea)) and fiber strain during the ejection phase (ef,e) were measured in the epicardial layers of the left ventricular anterior wall during normoxia and after 15 min of total occlusion (n = 5) or 30, 60, 120, and 180 min of partial occlusion of the left anterior interventricular coronary artery (LAICA; n = 11). Myocardial blood flow (MBF) was assessed with radioactive microspheres. Blood gases, pH, and lactate and Pi contents were determined in arterial, local venous, and coronary sinus blood. During normoxia, t(ea) and ef,e were similar in various epicardial regions of the left ventricular anterior wall. During total LAICA occlusion, in the ischemic area, subepicardial MBF decreased from 0...Continue Reading

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