Occult right ventricular dysfunction and right ventricular-vascular uncoupling in left ventricular assist device recipients

Abstract

BackgroundCurrent assessments remain insensitive for detecting right heart failure post left ventricular assist device (LVAD). Sensitive pressure-volume loop assessments of right ventricle (RV) contractility may improve our appreciation of post-LVAD RV dysfunction. MethodsThirteen LVAD patients and 20 reference (non-LVAD) subjects underwent comparison of echocardiographic, right heart cath hemodynamic, and pressure-volume loop-derived assessments of RV contractility using end-systolic elastance (Ees), RV afterload by effective arterial elastance (Ea), and RV-pulmonary arterial (RV-PA) coupling (ratio of Ees/Ea). ResultsLVAD patients had lower RV Ees (0.20±0.08 vs. 0.30±0.15 mmHg/ml, p=0.01) and lower RV Ees/Ea (0.37±0.14 vs 1.20±0.54, p<0.001) versus reference subjects. Low RV Ees correlated with reduced RV septal strain, an indicator of septal contractility, in both the entire cohort (r=0.68, p=0.004) as well as the LVAD cohort itself (r=0.78, p=0.02). LVAD recipients with low RV Ees/Ea (below the median value) demonstrated more clinical heart failure (71% vs 17%, p=0.048), driven by an inability to augment RV Ees (0.22±0.11 vs 0.19±0.02 mmHg/ml, p=0.95) to accommodate higher RV Ea (0.82±0.38 vs 0.39±0.08 mmHg/ml, p=0.002). Pulmonary artery pulsatility index (PAPi) best identified low baseline RV Ees/Ea (≤0.35) in LVAD patients (AUC=0.80); during ramp study, change in PAPi also correlated with change in RV Ees/Ea (r=0.58, p=0.04). ConclusionsLVAD patients demonstrate occult intrinsic RV dysfunction. In the setting of excess RV afterload, LVAD patients lack the RV contractile reserve to maintain ventriculo-vascular coupling. Depression in RV contractility may be related to LVAD LV unloading which reduces septal contractility.