Does increased work of the right ventricle diminish left ventricular function?

T he anatomic contiguity of the right and left ventricles suggests that alterations in the mechanical properties, configuration, or contractile performance of one chamber might influence the function of the other. By virtue of the anatomic arrangements of muscular fibers, right ventricular ejection is dependent on both longitudinal and cir-cumferential shortening of its free wall against a convex interventricular septum, whereas left ventric-ular ejection relies on a fairly uniform contraction of all portions of the cylinder (Fig 1A) .. The structural relationship between these chambers is such that marked changes in the size of the left ventricle will not ordinarily result in any fundamental changes in the bellows mechanism of right ventric-ular ejection. In contrast, the potential influence of increases in either right ventricular volume or in pressure-work on left ventricular systolic pump function, as well as diastolic compliance, is more apparent (Fig lB)-These anatomic considerations have led to experimental and clinical studies of left ventricular performance in the presence of an increased tension of the right ventricular wall. Overfilling of the normal right ventricle in isolated cardiac preparations results in a greater elevation of left ventricular end-diastolic pressure for a given level of left ventricular filling.2-3 Kelly et a!4 described similar changes in the diastolic pressure-volume curve of the left ventricle in dogs with chronic right ventricular pressure and volume overload ; however, this abnormal left ventricular compliance was normalized when the hypertrophied right ventricle was filled only to a normal end-diastolic pressure, thus demonstrating that the changes in left ventricular compliance were not secondary to any intrinsic alterations in ventricular distensibility. Kelly et al4 also demonstrated a modest decrease in both peak velocity of the contractile elements and peak change in pressure over time (dP/ dt) of the left ventricle in these animals with chronic right ventricular failure. Whether this systolic impairment was related to altered geometry or to biochemical changes, such as marked biventricular depletion of levels of catecholamines, was not resolved. That short-term changes in configuration have little effect on left ventricular function is supported by a study in dogs in which the main pulmonary artery was partially obstructed with a balloon. The ensuing right ventricular dilation caused a decrease in the septal-lateral wall diameter of the left ventricle, yet the left ventricular ejection fraction (LVEF) remained normal.5 Further studies would be required to resolve these apparent differences regard-1. Contraction patterns of the right and left …