Effect of regional ischemia on the left ventricular end-systolic pressure-volume relationship of isolated canine hearts
Sunagawa, K.; Maughan, W.L.; Sagawa, K.
Circulation Research 52(2): 170-178
1983
ISSN/ISBN: 0009-7330 PMID: 6825214 Document Number: 205358
The effects of regional ischemia on the left ventricular isovolumic end-systolic pressure-volume relationship (ESPVR) were studied in 6 excised, blood-perfused canine ventricles. Different extents of regional ischemia were created by ligating various branches of the coronary arteries while keeping the coronary arterial pressure constant (80 mm Hg). The extent of regional ischemia (Rm) relative to the total mass of the left ventricular myocardium was determined by regional myocardial blood flow measured by the radioactive microsphere technique. With regional ischemia, the ESPVR shifted rightward without significant change in slope in the physiologic end-systolic pressure range. In the subphysiological end-sysolic pressure range, however, its slope became lower than control. To quantify the degree of the rightward shift, the extrapolated volume axis intercept (Vo) was measured by fitting a stright line to the ESPVR in the physiological range under control and ischemic conditions. The shift in Vo (.DELTA.Vo) associated with ischemia was linearly correlated with Rm (.DELTA.Vo = 50.7Rm - 0.6, n = 28, r = 0.944, P < 0.001). Apparently, the major effect of acute regional ischemia on the ESPVR in the physiological pressure range is a parallel rightward shift. This forms a striking contrast to the effect of global ischemia (under which only the slope is affected without a substantial change in Vo).