Effect of Left Ventricular Volume on Right Ventricular End-Systolic Pressure-Volume Relation Resetting of Regional Preload

Effect of left ventricular (LV) volume on right ventricular (RV) end-systolic pressure-volume relation (ESPVR) was investigated, and the mechanism was examined from a standpoint of the alteration of RV free wall mean fiber length. Twelve cross-circulated isovolumically contracting canine hearts in which both ventricular volumes were controlled independently were used, and RV-ESPVR was determined at three different LV volume levels. At small (10.2±0.6 ml), middle (IS J±1.0 ml), and large (20.5±1.4 ml) LV volume, the slope of the RV-ESPVR was 2.63±0.13, 2.74±0.13, and 2.89±0.12 mm Hg/ml, respectively, and each value was significantly different from the others (/><0.01). The volume intercept (Vo) of the relation (RV-V0) was significantly decreased with the increment of LV volume (RV-V0 in small, middle, and large LV volume; 3.92±0.68, 3.39±0.67, and 2.87±0.71 ml, respectively; p<0.01). In nine hearts, RV free wall lengths in latitudinal and meridional direction were measured at three LV volume levels when RV volume was held constant (16.1 ±1.1 ml). RV latitudinal end-diastolic length was signifi-cantly augmented with increasing LV volume (latitudinal length in small, middle, and large LV volume; 9.68±0.55, 9.81±0.56, and 9.92±0.55 mm, respectively). RV meridional end-diastolic length also increased significantly with increasing LV volume. We concluded that RV-ESPV