Abstract 2171: The Rechargeable ICD: A new Application for a Well-Known Technology: Results of a Long-term Animal Study.
Current ICD-systems use a non rechargeable dry battery as energy source. Thus, the life span of these systems is limited by the capacity of their battery. Therefore, this project deals with the development of a device (rechargeable ICD - rICD) being recharged transcutaneously by a magnetic field.
Method: A prototype of this rICD consisting of an 4th generation ICD housing containing a lithium polymer rechargeable battery, a charging coil for receiving the transmitted energy, integrated circuits for charging controls and a new telemetry system. These devices were tested in a long-term animal study in 10 Merino sheep (age 2±0.5 years, weight 54±9 kg) over a period of 1 year. By means of the telemetry system, the rICD was controlled. State of charge, LiIon voltage, charging current and temperature of LiIon battery, electronics and rICD housing were monitored continuously. Under general anaesthesia (ITN), the prototypes were implanted on the lateral neck of the sheep. The implantation of the devices, positions of charging coils and telemetry antennas as well as the implantation depths were documented by means of x-ray. All animals underwent monthly follow-ups with full charge-discharge cycles. At last, the animals were euthanatized and the ICD pockets were excised and analyzed microscopically.
Results: Implantations were successful in all animals. Mean implantation depth was 2.2±0.6 cm. Monthly follow-up measurements showed that neither the tissue exposed to the electromagnetic field nor the device itself nor the LiIon battery presented with significant heating. Mean charging current was 34±11 mA. Thus, efficient charging of the LiIon battery was possible. One animal presented with a pocket infection. Other tissue alterations of the ICD-pockets have not been observed.
Conclusion: The transcutaneous wireless energy transfer for rechargeable ICDs has been shown to be reliable, stable and effective in a long-term animal study.