(E-184) LVAD Speed Optimization for Right Heart Failure Prevention

Left Ventricular Assist Device (LVAD) therapy for end-stage heart failure patients presents challenges to optimize device-patient hemodynamic interaction. Up to 44% of LVAD patients later develop right heart failure (RHF) in part due to the LVAD causing more strain on the right side circulation. With the lack of information about how the right side is affected by LVAD operation, hemodynamic optimization of LVAD therapy is a current clinical challenge. Learning more about how the right side of the heart operates and is affected by changes to the LVAD would allow for better optimization and potentially reduce LVAD-induced RHF. This study uses patient data from a clinical setting in conjunction with virtual patient hemodynamic models of the cardiovascular system to explore how the right side of the heart is affected by changes in LVAD operation. 

25 patients implanted with a Heartmate III LVAD at the University of Florida and who underwent right heart catheterization were reviewed in this retrospective study. A virtual patient hemodynamic model designed to mimic the cardiovascular system using a lumped parameter approach was developed. The model incorporated over 50 physiological parameters and the LVAD pump pressure-flow relationships to allow customization for each patient. The main parameters used to optimize LVAD performance were mean arterial pressure (MAP) target, LVAD speed, patient vascular resistance, ventricular contractility and compliance. 

Data from 25 patients implanted with LVADs obtained pre implantation, post implantation, and after speed optimization were used in this retrospective study. Utilizing patient parameters obtained in the clinic, virtual patient models were customized for each patient. Following this, optimization using the cardiovascular model was compared to optimization in the clinical setting. Two trials were conducted, one using the clinically optimized MAP as the target and the second using idealized MAP values (70, 80, and 90 mmHg) as the MAP target. From these tests, a median baseline of 5100 RPM was determined. The virtual patient model recommended a median speed increase for all patients of 300 RPM. The clinical and model optimizations had a median difference of around 60 RPM.  A combination of higher LVAD speed and lower MAP could potentially lead to right-sided pressure-volume overload and potentially precipitate right heart dysfunction. Using different idealized MAP targets enables comparing the virtual patient model optimization and the clinical procedure towards guiding customized therapy. 

1Holly Grant, 2Lauren Meece, 2Mustafa Ahmed and 1Venkat Keshav Chivukula