DESING AND DEVELOPMENT OF A COMPACT PULSATILE ELECTRIC-LVAD USING CAD/CAM AND CFD TECHNOLOGY

Abstract

In this study, we have developed a new miniature motor-driven pulsatile LVAD in order to implant into average Japanese using CAD/CAM technology. The LVAD actuator consists of a blushless d.c. motor and a ball-screw. The ball-screw converts motor's rotational motion into rectilinear motion to drive a blood pump. A miniature ball-screw (volume of 6.1 ml) was developed to minimize the LVAD actuator. Small Nd-Fe magnets were fixed on a pusher-plate, and an iron plate was adhered on a diaphragm. Optimum magnetic attractive force between Nd-Fe magnets and the iron-plate fill the pump with blood actively during filling phase. The blood pump (stroke volume 55 ml) was designed by CAD software. Geometry of the blood pump was evaluated by means of value of IPG = (mean Reynolds shear stress) × (Occupied Volume) and flow velocity distribution with track of blood flow using CFD software. Calculated value of IPG was varied form 20.6 Nm to 47.1 Nm depending on small difference in pump geometry. Mainframe of the pump actuator was made of duralumin, a casing of the actuator and the blood pump was made from epoxy resin. While the volume and weight of the new LVAD became 287 ml and 378 g, further miniaturization of it will be available by improvement of geometry of both the blood pump and a back casing. We are also developing a high-performance control system for the new LVAD and are going to evaluate pump performance in vitro and in vivo test.