CARD19: Hemodynamic Capabilities of biventricular HM3 Support

Background: Severe biventricular failure may necessitate the use of biventricular support using two HeartMate 3 (HM3) devices, with the right sided device in an off-label setting. Quantitative analysis of the hemodynamic capabilities has not yet been published. The aim of this study was to extensively investigate the balance between left and right flow, atrial pressures and septal positioning with and without pump speed changes during biventricular HM3 support. Methods: A mock circulation loop was configured to simulate a dual HM3 supported biventricular heart failure condition with left ventricular and right atrial inflows for the left and right pump respectively. Speed adjustments were made to balance systemic and pulmonary flow rates, atrial pressures (left atrial pressure (LAP) 10-15 mmHg, right atrial pressure (RAP) 7-12 mmHg), and septal position (ventricular end diastolic volume (VEDV) difference < 50 mL) to achieve a baseline condition. Systemic hypotension ((SHpo) mean arterial pressure (MAP) < 65 mmHg by decreasing SVR from 1000 to 600 dynes s/cm5), systemic hypertension ((SH) MAP > 106 mmHg by increasing from SVR 1000 to 2000 dynes s/cm5) and pulmonary hypertension ((PH) mean pulmonary arterial pressure (MPAP) > 20 mmHg by increasing PVR from 80 to 300 dynes s/cm5) were independently simulated and results recorded. Left and right pump speed manipulations were completed for each condition in an attempt to restore the flows, atrial pressures and septal position. Results: The largest change in pump speed (LVAD: 6000 to 8200 rpm, RVAD: 2950 to 4900 rpm), was required to restore the simulated condition of SHpo. PH had the biggest impact on the atrial pressures, with LAP down to 4.11 mmHg and RAP up to 13.29 mmHg compared to 10.88 mmHg and 11.11 mmHg at the restored baseline condition respectively. Through HM3 speed manipulation, the LAP was restored to 7.08 mmHg and the RAP to 12 mmHg. PH had the most significant impact on the left and right VEDV difference, with an increase from 28 mL at the restored baseline condition to 228 mL during PH. This imbalance was reduced to 133 mL by adjusting both pump speeds, but could not be restored to the target of 50 mL. Conclusion: Systemic and pulmonary flow and atrial pressures can be restored through pump speed manipulation with biventricular HM3 support during simulations of severe SH. Restoring flows, atrial pressures and septal position was not possible in all conditions when relying solely on pump speed changes.Figure 1. Atrial pressures at different conditions, HF – heart failure; SH – systemic hypertension; SHpo – systemic hypotension; PH – pulmonary hypertension; LAP, RAP – left and right atrial pressures.Figure 2. Ventricular end diastolic volume difference at different conditions, HF – heart failure; SH – systemic hypertension; SHpo – systemic hypotension; PH – pulmonary hypertension; LVEDV, RVEDV – left and right end diastolic volume.