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 19 W. 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 the 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 4.4-7.0 L/min (50-110 bpm). For continuous operation at 70 bpm, the DC-to-DC energy transmission efficiency was 81% or more, the pump output flow was 6.2 L/min, and the temperature in the part of implantation was lower than 41°C, a temperature that can hardly affect a living body