Interventricular Interactions and Right Ventricular Function in LVAD Recipients: Insights from Pressure Volume Analyses

Abstract

<h3>Purpose</h3> Data supporting the hypothesis that interventricular interaction contribute to right ventricular (RV) failure after left ventricular assist device (LVAD) implantation are lacking. <h3>Methods</h3> Patients underwent a protocolized hemodynamic ramp test where RV pressure-volume (PV) loops were recorded with a conductance catheter. The end-systolic PV relationship was characterized by the ratio of end-systolic pressure and volume (R_es). The end-diastolic PV relationship (EDPVR) was characterized by the V₁₀ index (i.e., the volume at which the EDPVR reaches a pressure of 10 mmHg). ΔR_es and ΔV₁₀ (i.e., the maximal change across the range of tested LVAD speeds) were used to compare systolic and diastolic function between patients. <h3>Results</h3> Six adult males with HeartMate3 LVADs completed the study protocol (Fig. 1). ΔR_es and ΔV₁₀ both exhibited minimal changes in 3 subjects (mean ΔR_es=7.24%, mean ΔV₁₀=8.14 mL), suggesting neither RV systolic nor diastolic function was impacted by LV unloading. In contrast, 2 subjects showed predominantly diastolic responses to changing LVAD speed (mean ΔV₁₀=17.4), but no significant systolic response (mean ΔR_es=5.47%). The final subject's ramp study was stopped prematurely because of suction events: ΔR_es and ΔV₁₀ were 23.2% and 1.4 mL, respectively, indicating a significant decrement in systolic function with greater LVAD speed. The mean PA systolic pressures were significantly greater in the 3 participants without systolic or diastolic changes relative to their counterparts (42.3 vs. 25.3 mmHg, p=0.038). <h3>Conclusion</h3> Interventricular interaction exerts a heterogenous influence on RV performance: Systolic interactions diminish RV contractile function, while diastolic interactions improve RV compliance. Further work is required to establish whether interventricular interaction is, indeed, a rare cause of post-LVAD RV dysfunction, and if chronic exposure to afterload blunts the RV's sensitivity to interventricular interaction.