Efficiency improvement and in vivo estimation of externally-coupled transcutaneous energy transmission system for a totally implantable artificial heart

In order to enhance the implantability of the externally-coupled transcutaneous energy transmission system (ECTETS), efficiencies in various parts of the circuit system were improved to reduce heat dissipation. As a result. a DC-to-DC energy transmission efficiency of 85% or more was obtained in an in vitro experiment conducted at a power output of 19W. In the in vivo measurement of this improved ECTETS with the internal coil and the rectifier circuit implanted under the skin of a living goad, a DC-to-DC energy transmission efficiency of 82% or more was obtained. Fluctuation of efficiency due to movement of the body was found to be less than 0.5%. when this improved ECTETS is used with die totally implantable electrohydraulic artificial heart with an overflow mock circulatory system connected as a load. the pump output flow at a changing heart rate was found to be 4.4-7.0L/min (50-110bpm). For continuous operation at 70bpm, the DC-to-DC energy transmission efficiency was 81% or more, the pump output flow was 6.2L/min, and the temperature in the part of implantation was lower than 41 degrees C, a temperature that can hardly affect a living body.