Abstract
To better understand the clinical implication of left ventricular assist system (LVAS) on right ventricular (RV) function, RV pressure-cross sectional area data were obtained in five patients undergoing Novacor LVAS implantation. RV pressure was acquired simultaneously with digitized RV cross sectional area obtained through transesophageal echocardiograms. While altering loading conditions, maximum area elastance (aEmax), end diastolic pressure-area relation (EDPAR) and stroke work-end diastolic area relation (PRaSW) were assessed before and one hour after LVAS implantation. Three patients (Group A) required minimal inotropic support for the RV, while two patients (Group B) required temporary mechanical support for RV failure. The slope of PRaSW in group A increased from 10.7mmHg (mean) to 18.8 but, in Group B, the slope decreased from 11.5 to 3.8. The intensity of the curvature indicative in EDPAR decreased in both groups (Group A; K1: from 0.17 to 0.09, Group B; from 0.03 to 0.01, where K1 is a parameter described in EDP=e (K1*EDA+K2)). In all patients, peak RV pressure (afterload) decreased dramatically (Group a; from 38.4mmHg to 27.9, group B; from 42.3 to 29.3) contributing to an increase in RV stroke work. In Group A, aEmax increased from 2.53mmHg/cm2 to 3.70, however in Group B, there was no change. These results suggest that the improvement of RV performance was achieved by 1) increasing diastolic function (EDPAR) 2) increasing mechanical efficiency by abrupt afterload reduction and 3) improving contractility (aEmax). Deterioration of performance is related to a decrease in systolic function.
