DEVELOPMENT OF THE DIRECT ELECTROMAGNETIC VENTRICULAR ASSIST DEVICE

Abstract

The main purpose of the study is to develop a new implantable direct electromagnetic ventricular assist device (DEM-VAD) that uses a linear oscillatory actuator (LOA) without any movement converter. The first model (DEM-VAD1) was developed in 2002, of which an in vitro test demonstrated 6 L/min output and 15 % maximum efficiency at 130 bpm. However, the experiment proved that the heat generated by the actuator was still too high. To overcome this problem, the second model (DEM-VAD2) was newly designed. The pump unit consisted of two pump housings, a pusher-plate, a diaphragm and the LOA. Pump housings and the pusher-plate of DEM-VAD1 were made of a high polymeric material, which was inadequate in terms of thermal conductivity and heat radiation. In the DEM-VAD2, we used aluminum alloy for the bottom housing and the pusher-plate material. However, if the diaphragm is to be glued to the pusher-plate, there was a possible danger of separation of the parts. The design of the model was altered to overcome this problem, placing the diaphragm between the pusher-plate and the metal ring as in a D-H junction. The completed DEM-VAD2 was 101 mm in diameter, 47 mm in length, 300 ml in volume and 770 g in weight. The maximum pump output was 9 L/min. The maximum pump efficiency was about 17%. The temperature was measured after 1 h of pump operation (10/100 mmHg, 120 bpm, 10 W). The temperature of the stator-core of the LOA rose by 4 °C at room temperature. The results showed that the improvement of the heat generated by the actuator was effective in the second model.