Abstract
INTRODUCTION: Progressive developments in mechanical circulatory support devices have seen the increasing use of devices which directly augment pulmonary blood flow, including the deployment of durable pumps in the biventricular configuration (BiVAD). This paradigm introduces complex haemodynamic interactions which have not been fully characterized, compared to LVAD alone. We sought to investigate the effect of BiVAD support on central hemodynamics with particular regard to assessing pulmonary flow and vascular properties. METHODS: This retrospective cohort study included LVAD and BiVAD patients who had right heart catheterization (RHC) performed within 6 months prior to MCS implantation and thereafter. Traditional RHC parameters, native LV and RV stroke volume (SV), and measures of pulmonary vascular function, including pulmonary arterial compliance (PAC) and elastance (E(PA)), were compared between BiVAD and LVAD patients. RESULTS: A total of 62 patients, 13 (21%) BiVAD and 49 (79%) LVAD patients, were studied. At follow-up, despite similar baseline values, the BiVAD vs LVAD cohort had significantly higher pulmonary artery pressures (mmHg): sPAP (37 ± 14 vs 28 ± 11, p = 0.02) and dPAP (22 ± 8 vs 12 ± 6, p < 0.001). A reduction in PVR following BiVAD insertion was observed but remained significantly greater in BiVAD vs LVAD patients (2.1 ± 1.1 vs 1.6 ± 0.6 Wood Units, p = 0.02). Pulmonary arterial compliance (PAC), calculated using "total" stroke volume (SV) comprising the pulsatile and continuous flow components of the BiVAD configuration) was higher in BiVAD vs LVAD patients. However, using the native right ventricular SV, PAC was lower in the BiVAD cohort and remained unchanged compared to baseline. Simulation modeling demonstrated BiVAD support modestly increases pulmonary artery pressure and reduces right heart output, which was observed in our study. CONCLUSION: The presence of combined pulsatile and continuous flow in BiVAD patients significantly influences the hemodynamic profile compared to LVAD patients, particularly in regard to pulmonary pressures. Our study highlights the potential challenges in applying conventional pulmonary vascular hemodynamic indices in patients with continuous flow components.