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

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Abstract
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 less than .001) and septal-lateral dimension by 8 +/- 5% (p less than .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 end-diastolic 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.