A Two-Stage Ventricular Assist Device for Pediatric Patients

Implantable ventricular assist devices to support pediatric patients with left ventricular failure remain an unmet medical need. The aim of this work was to assess the feasibility of a miniaturized two-stage pump concept as a left ventricular assist device (LVAD) intended for small pediatric patients.

The pump leverages a two-stage design with a back-to-back impeller configuration. Computational fluid dynamics (CFD) alongside finite element method (FEM) analysis were utilized to design the pump and its actuation. The magnetic and hydrodynamic properties of the axial and radial bearing were designed and analyzed considering the motor characteristics. The hydraulic performance was validated in a flow loop, and hemocompatibility parameters were numerically assessed and compared to the HeartMate 3.

At design condition of 1.5 L/min and 6400 rpm, the Two-Stage Pump builds up a pressure of 58 mmHg. The dynamic analysis of the radial hydrodynamic journal bearing demonstrated that an impeller equilibrium position can be achieved by introducing an additional radial load to balance the forces. The axial reluctance force of the motor is shown to be sufficient to balance the axial forces. The motor losses of 0.18 W result in a local temperature increase of 0.4 K. Compared to the HeartMate 3, the Two-Stage Pump demonstrates similar or even superior hemocompatibility results for pediatric use at a reduced circumferential velocity of 3.7 m/s.

The concept of the Two-Stage Pump demonstrates feasibility and presents compelling results to address the medical challenge of an implantable LVAD for pediatric patients.