Development of linear motor driven pulsatile ventricular assist device

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Heart transplantation is a reliable way to treat patients with severe cardiac failure. The limited number of donor hearts available requires the establishment of alternative treatments for these patients. A left ventricular assist device(VAD) has been used for such patients and has shown reliable results as a bridge to heart transplantation. Electromechanical and electrohydraulic mechanisms have been reported as the driving mechanisms for pulsatile VADs. These require a movement converter, such as a roller screw. This causes problems in that the use of the movement converter prevents the VAD from becoming smaller and reduces the reliability of the VAD.In this study, a new implantable direct electromagnetic VAD (Linear-VAD) was developed, that uses a linear oscillatory actuator(LOA) without any movement converter. A magnetic field analysis was applied to examine proposal structures and to design LOA. The three proposal structures of LOA are as follows :(1)New structure of the Inner-Stator/Outer-Mover.(2)New structure which has the non-symmetrical thrust characteristics.(3)The structure to improve the starting thrust.The dimensions of prototype LOA are 60 mm in diameter, 24 mm in thickness, with a mass of 465 g and a volume of 68 mL, Moreover, the prototype Linear-VAD was developed that uses the LOA. The dimensions of the first prototype Linear-VAD are 96 mm in diameter, 50 mm in thickness, with a mass of 0.62 kg and a volume of 280 mL. An in vitro test demonstrated over 10 L/min maximum output and 18 % maximum efficiency. The Linear-VAD was evaluated for pump performance, long-term durability in a chronic animal experiment. The goat implanted with the Linear-VAD survived for 42 days. The Linear-VAD had no troubles relating to the electronic control unit or the electronic drive line. The experiment confirmed the durability of the Linear-VAD for 42 days.