Left ventricular diastolic chamber stiffness and intramyocardial coronary capacitance in isolated dog hearts

Abstract

Background. Because the myocardium is perfused primarily during diastole, changes in diastolic properties of the left ventricle (LV) should influence the intramyocardial circulation. Methods and Results. We examined the influence of LV diastolic properties on the magnitude and localization of intramyocardial coronary capacitance by analyzing the coronary pressure-venous flow relation in isolated, isovolumic dog heart preparations. After sudden occlusion of the left coronary artery during a long diastole, we measured precapacitance and postcapacitance resistances (RPRE and RPOST) and calculated intramyocardial coronary capacitance (CIM) from RPOST and the time constant of the coronary venous flow decay. Using this method, we characterized the effects of coronary vasodilation, LV diastolic volume, and LV diastolic chamber stiffness on the coronary circulation. The magnitude of CIM increased from 0.09±0.01 to 0.24±0.20 mL · mm Hg-1 · 100 g-1 (P