Alterations in left ventricular compliance due to changes in right ventricular volume, pressure and compliance.

Because of ventricular interdependence, part of the measured left ventricular diastolic pressure can be attributed to the right ventricle. Therefore, we examined the hypothesis that left ventricular diastolic properties are modified by alterations in right ventricular compliance and pressure even without a change in right ventricular volume. To examine this hypothesis, the hearts were removed from six dogs, the coronary arteries perfused with cool cardioplegic solution, and the hearts submerged in cool cardioplegic solution. Balloons were inserted into each ventricle. Left ventricular pressure-volume curves were recorded and approximated by an exponential equation. With no fluid in the right ventricular balloon (control), the exponential coefficient and constant were 0.038 (SD 0.004) ml-1 and 2.38(0.75) mm Hg respectively. With right ventricular pressure held constant at 20 mm Hg, the exponential coefficient and constant were 0.035(0.002) ml-1 and 3.71(1.64) mm Hg (p less than 0.05 v control constant), respectively. With a fixed right ventricular volume, the exponential coefficient and constant were significantly different (p less than 0.05 v control values) at 0.040(0.006) ml-1 and 2.81(0.96) mm Hg, respectively. After decreasing right ventricular free wall compliance by injecting glutaraldehyde into the right coronary artery, the exponential coefficient and constant were significantly different (p less than 0.01 v control values) at 0.058(0.010) ml-1 and 1.86(0.60) mm Hg, respectively. Thus, even with a constant right ventricular pressure or volume, a significant upward shift in the left ventricular pressure-volume relation occurred. Decreasing right ventricular free wall compliance further increased left ventricular pressure. The results of these studies indicate that the diastolic properties of the left ventricle can be modified by changes in right ventricular pressure and compliance even without a change right ventricular volume. Thus indices of left ventricular diastolic properties may be altered by changes in the characteristics of the right ventricle.