Magnetic-Field Immunity Examination and Evaluation of Transcutaneous Energy-Transmission System for a Totally Implantable Artificial Heart

Transcutaneous energy transmission (TET) is the most promising noninvasive method for supplying driving energy to a totally implantable artificial heart. Induction-heating (IH) cookers generate a magnetic flux, and if a cooker is operated near a transcutaneous transformer, the magnetic flux generated will link with its external and internal coils. This will affect the performance of the TET and the artificial heart system. In this paper, we present the design and development of a coil to be used for a magnetic immunity test, and we detail the investigation of the magnetic immunity of a transcutaneous transformer. The experimental coil, with five turns like a solenoid, was able to generate a uniform magnetic field in the necessary bandwidth. A magnetic-field immunity examination of the TET system was performed using this coil, and the system was confirmed to have sufficient immunity to the magnetic field generated as a result of the conventional operation of induction-heating cooker. 1. Introduction Immediate energy transmission using a cable is an easy method for supplying driving energy to a totally implantable artificial heart [1–5]. However, this method increases the risk of infectious disease and decreases the patient’s quality of life (QOL). Transcutaneous energy transmission (TET) is the most promising non-invasive method of energy transfer [3–5]. If an artificial heart stops because of malfunctioning of the TET system, the consequences are fatal. Therefore, according to the Pharmaceutical Affairs Act in Japan, an evaluation of electromagnetic compatibility (EMC) is indispensable [5]. The EMC requirements for an artificial heart system state that it is necessary to reduce the electromagnetic interference (EMI) and electromagnetic susceptibility (EMS) while maintaining performance. However, even if the examination satisfies the Pharmaceutical Affairs Act, the safety of the system is not necessarily guaranteed from the viewpoint of EMC. Recently, there have been some reports on the malfunctioning of medical devices such as pacemakers that was caused by magnetic-field leakage from induction-heating (IH) cookers [6]. However, EMS evaluation that assumes such an event is not currently obligatory for medical equipment. A transcutaneous transformer transmits driving energy to an artificial heart implanted inside the body by using electromagnetic induction between two coils inside and outside the body. IH cookers generate a magnetic flux, and if a cooker is operated near a transcutaneous transformer, the magnetic flux generated will link with the