Effect of the normal pericardium on the left ventricular diastolic pressure-volume relationship

Closed chest placement of tantalum screws in the endocardium was performed an biplane cineradiography of these markers was used to measure LV dimensions while changing total blood volume. Measurements were then repeated following thoracotomy, pericardiotomy and reclosure of the thorax. The LV pressure-volume curves obtained after pericardiotomy always were shifted down and to the right from curves obtained before thoractomy and pericardiotomy. The divergence between the curves increased as LV volume increased, the curves being identical at small LV volumes and at low diastolic pressures. In each experiment the curves diverged before LV diastolic pressure exceeded 10 mm Hg, however.