Development of linear motor driven pulsatile ventricular assist device

心脏移植是治疗严重心力衰竭患者的可靠方法。可用的捐赠者心脏数量有限，需要为这些患者建立替代治疗方法。左心室辅助装置(VAD)已被用于此类患者，并已显示出可靠的结果，作为心脏移植的桥梁。据报道，驱动脉冲式VAD的机构有机电机构和电液机构。这些需要运动转换器，如滚柱螺杆。在本研究中，开发了一种新型植入式直接电磁VAD(Line-VAD)，它使用了一个线性振荡驱动器(LOA)而不需要任何运动转换器。磁场分析被应用于检查提议的结构和设计LOA。提出了三种LOA结构：(1)内/外动子结构。(2)具有非对称推力特性的新结构。(3)改进启动推力的结构。LOA原型尺寸为直径60 mm，厚度24 mm，质量465g，体积68mL。第一台样机的直径为96 mm，厚度为50 mm，质量为0.62公斤，体积为280毫升。体外试验最大产量超过10 L/分钟，最大效率18%。在一项慢性动物实验中，对Line-VAD的泵性能和长期耐用性进行了评估。植入Line-VAD的山羊存活42天。Line-VAD没有与电子控制单元或电子传动线有关的故障。实验证实了线性VAD的耐久性为42天。

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.