Feasibility of a remote monitoring system for patients with an implantable left ventricular assist device using Personal Handy-Phone System telecommunication technology

Abstract

We have been developing a remote monitoring system for patients with implanted artificial hearts. The remote monitoring system consists of two digital data links: an electromagnetic transcutaneous digital-data transmission (TDT) system between an artificial heart controller inside the body and a mobile computer outside the body, and a public high-speed data transmission service using PHS (Personal Handy-Phone System) between the mobile computer and a host computer in a hospital. The TDT system mainly consists of an ASK (Amplitude Shift Keying) circuit with carrier electromagnetic wave frequencies of 4MHz and 10 MHz and corresponding demodulation circuit, thin loop coil antennas for transmission and receiving, and a one-chip microcomputer for the alarm system for indicating misalignment of antennas outside the transmittable range to ensure error-free data transmission. In our remote monitoring system, motor current and motor rotational angle data from the implanted controller are framed together by a control code for data error checking and correcting at the receiving site, and the data are sent through the PHS connected to the mobile computer. GPS (Global Positioning System) positioning data are also sent to the host computer with control codes. The host computer calculates pump outflow and arterial pressure and displays the data in real-time waveforms. The host computer also displays the patient's position on the map and the condition of the batteries. The results of this study showed that the driving condition of the artificial heart and the subject's position could be remotely monitored on the host computer. It could be concluded that this monitoring system is useful for remote monitoring of patients with an implanted artificial heart.