Numerical Evaluation of a Novel Two-Stage Ventricular Assist Device for Pediatric Patients

Abstract

Objectives: Currently, no intracorporeal left ventricular assist device (LVAD) is commercially available for small pediatric patients. The requirements of small size and excellent hemocompatibility at low-flow conditions pose a distinct challenge for the development of a pediatric LVAD. This study aimed to assess the feasibility of a novel, miniaturized two-stage pump to meet these specific requirements.

Methods: The design of the novel pediatric LVAD features two pump stages with a back-to-back impeller as a single rotating part. The impeller is hydrodynamically suspended in the radial direction and axially centered through reluctance forces. This enables miniaturization together with a reduction in circumferential velocity while achieving the required pressure head. Computational fluid dynamics was used to evaluate the pump performance. Washout of the priming volume was assessed through a passive scalar transport and pump-induced blood trauma through a power law model for the normalized index of hemolysis (NIH). Results were compared to the performance of the state-of-the-art LVAD HeartMate3 under the same pediatric operating conditions.

Results: The two-stage pump shows a pressure head of 55mmHg at a flow rate of 1.5L/min with a circumferential velocity of 3.7m/s at a hydraulic efficiency of 33%. With a total priming volume of 3.7mL a washout of 95% is obtained in 0.17s, and the predicted NIH is 4.0mg/100L. In comparison, the HeartMate3 reaches a 95% washout of its 14.5mL priming volume after 0.86s with an NIH of 6.7mg/100L at a circumferential velocity of 4.1m/s.

Conclusions: The proposed two-stage pump builds up the required pressure head at a smaller size and reduced circumferential velocity, resulting in improved numerical hemocompatibility metrics compared to the HeartMate3 at pediatric operating conditions. Further in vitro experiments will be performed to validate the numerical results. Overall, the two-stage pump may successfully tackle the low-flow challenges for pediatric LVADs.