VENTRICULAR PERFORMANCE Effects of right ventricular ischemia on left ventricular geometry and the end - diastolic pressure - volume relationship in the dog

We studied the effects of right ventricular ischemia on left ventricular three-dimensional geometry and the end-diastolic pressure-volume relationship in 16 open-chest dogs before and after pericardiectomy. Left ventricular volume was calculated from three internal dimensions measured with ultrasonic crystals. In one group of eight dogs, right coronary artery (RCA) occlusion for 2 min with the pericardium intact reduced aortic flow by 24 ± 9% (p < .001) and septal-lateral dimension by 8 ± 5% (p < .01), without changing anterior-posterior and apical-basal dimensions. However, parameters of left ventricular systolic function (aortic flow, left ventricular systolic pressure, peak dP/dt, and mean percent systolic shortening) were similar to those observed at a comparable level of left ventricular enddiastolic volume during inferior vena caval occlusion. In the other group of eight dogs, during RCA occlusion before pericardiectomy the left ventricular end-diastolic pressure-volume relationship determined during rapid blood transfusion shifted leftward and upward significantly from the preocclusion relationship. After pericardiectomy, RCA occlusion caused less significant changes in aortic flow and septal-lateral dimension as well as in the left ventricular end-diastolic pressure-volume relationship. We concluded that right ventricular ischemia causes a leftward shift of the interventricular septum in end-diastole and an alteration of the left ventricular end-diastolic pressure-volume relationship without changing left ventricular myocardial performance. These changes are enhanced by the intact pericardium. Circulation 72, No. 5, 1104-1114, 1985. AN INCREASE in right ventricular filling' and the presence of the pericardium2 have been shown to cause a leftward and upward shift of left ventricular diastolic pressure-volume curves.3 Also, there is experimental evidence that the interventricular septum shifts leftward in end-diastole and left ventricular geometry is distorted when right ventricular loading is induced by pulmonary artery constrictions,4 atrial septal defect,6 the Mueller maneuver7 or positive end-expiratory pressure ventilation.8 However, the effects of right ventricular infarction or ischemia on left ventricular diastolic properties have not yet been reported. Although Goldstein et al.9 showed that elevated intrapericardial pressure after right ventricular infarction could reduce left ventricular preload and cardiac output, they neither From the Departments of Cardiovascular Dynamics and Internal Medicine, National Cardiovascular Center, Osaka, Japan. Address for correspondence: Yoichi Goto, M.D., Department of Cardiovascular Dynamics, National Cardiovascular Center, 5-71, Fujishirodai, Suita. Osaka, 565, Japan. Received Dec. 31, 1984; revision accepted July 5, 1985. Presented in part at the 56th Scientific Sessions of The American Heart Association, Anaheim, CA, 1983. evaluated left ventricular geometry nor measured left ventricular volume. The goal of the present study was to elucidate the effects of right ventricular ischemia on left ventricular geometry and the end-diastolic pressure-volume relationship in dogs, and to consider the importance of the intact pericardium. To this end, we measured septallateral, anterior-posterior, and apical-basal dimensions of the left ventricle with three pairs of ultrasonic dimension gauges, during right coronary artery (RCA) occlusions with the pericardium intact and open.