Ventriculo-Arterial Coupling and Speed Modulations in Rotodynamic Blood Pumps

Clinical evidence indicates that myocardial recovery during left ventricular assist device (LVAD) therapy is influenced by mechanical unloading. Strategies restoring physiological ventriculo-arterial (VA) coupling may promote recovery. Therefore, this study investigated whether rotodynamic blood pumps (RBP) operated in modulated rotational speed can optimize ventriculo-pump-arterial (VpA) coupling and improve mechano-energetic performance. VpA coupling was assessed using a hybrid mock loop simulating a virtual 30-kg pediatric patient under moderate and end-stage heart failure (HF). Constant-speed operation, symmetric pulsatile profiles (sinusoidal and step), and an asymmetric step profile (30%/70% high/low speed duration) were tested at varying phase delays after systole onset. Key findings were validated in an isolated large-animal heart model, including analysis of VA/VpA coupling and cardiac efficiency. Constant speed LVAD support worsened VpA coupling (moderate HF: 1.50 to 1.79; end-stage HF: 4.19 to 7.67). In contrast, symmetric pulsatile profiles during copulsation improved coupling (moderate HF: sine/step 1.32/0.97; end-stage HF: sine/step 3.30/2.52) and arterial pressure pulsatility (moderate HF: sine/step +40%/+74%; end-stage HF: sine/step +132%/+225%) but caused significant diastolic backflow. The asymmetric step profile maintained improved matching (moderate/end-stage HF: 0.97/2.86) and arterial pulsatility (+58%/+174%) while reducing backflow. Isolated heart experiments confirmed improved coupling, arterial pulsatility and maximized cardiac efficiency at optimized phayse delays (70-90% delay). Cardiac cycle synchronized operation of RBPs in co-pulsation improves VpA coupling, cardiac efficiency and arterial pulsatility compared with constant-speed support. Tailoring pulsatile profiles to cardiac timing and residual function may enable more physiological support and promote recovery-oriented LVAD therapy.