Development of linear motor driven pulsatile ventricular assist device

心脏移植是治疗严重心力衰竭的可靠方法。可获得的供体心脏数量有限，因此需要为这些患者建立替代治疗方法。左心室辅助装置（VAD）已用于此类患者，并已显示出可靠的结果，作为心脏移植的桥梁。机电和电液机构已被报道为脉动式VADs的驱动机构。这需要一个运动转换器，如滚柱螺杆。这导致的问题是，使用运动转换器会阻止VAD变得更小，并降低VAD的可靠性。本研究开发了一种新型的可植入式直接电磁VAD (linear -VAD)，该VAD采用线性振荡致动器（LOA），不使用任何运动转换器。磁场分析应用于检查提案结构和设计LOA。LOA的三种结构方案如下：(1)内定子/外动器的新结构。(2)具有非对称推力特征的新构造。(3)提高起动推力的结构。LOA原型直径为60 mm，厚度为24 mm，质量为465 g，体积为68 mL，并开发了使用LOA的Linear-VAD原型。第一台样机Linear-VAD的直径为96毫米，厚度为50毫米，质量为0.62千克，体积为280毫升。体外测试表明，最大输出超过10升/分钟，最大效率为18%。在慢性动物实验中，对线性vad的泵性能和长期耐久性进行了评估。植入Linear-VAD的山羊存活42天。线性vad没有与电子控制单元或电子驱动线有关的问题。实验证实了Linear-VAD的耐用性为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.