Research and development of an electrohydraulic totally implantable artificial heart system for practical use

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An electrohydraulic totally implantable artificial heart (EHTAH) system has been developed. The system comprises of diaphragm-type blood pumps, an electrohydraulic actuator consisting of a regenerative pump-brushless DC motor assembly, a transcutaneous energy transfer unit (TET, an optical tgelemetry unit, and an electronic unit consisting of internal battery and controller. The enery converter, reciprocating hydraulic oil to alternate blood pumps through flexible oil conduits, is to be placed in the abdominal region in clinical use for minimizing anatomic constraints. In the 5th iteration prototype, the maximum output was over 13 L/min, and the energy consumptiuon and energy efficiency were around 10 W and 14 % at 5L/min output, respectively. The pumping unit with an external controller has been implanted in 17 calves of as small as 54 kg, and the longest surviving animal, which lived for over 12 weeks, along with the other 2 over-6-weeks long-term survivors, demonstrated good general condition. During the experiment, the animal's circulation was stably maintained by the EHTAH with an adequate left-right output balance. Generation and dissipation of heat from the device was also acceptable. The device demonstrated good anatomic fit at autopsy without compromising the great vessels and adjacent tissues. Initial implantation of subtotal system including TET and elctronic units was further conducted with another calf weighing 72 kg, which survived for 3 days with a comploetely tether-free system. An implantable ventricular assist device (EHVAD) was also developed by utilizing the left blood ppump and actuator of the EHTAH,which were packaged in a metal casing) with a compliance chamer. In vitro testing demonstrated over 9 L/min of maximum output and over 13 % maximum efficiency. The initial animal testing lasted for 25 days until termination due to accident. Based on these favorable results, the EHTAH and EHVAD are being put into translational stage for practical use.