A remote monitoring system for patients with implantable ventricular assist devices with a personal handy phone system

The usefulness of a remote monitoring system that uses a personal handy pho ne for artificial heart implanted patients was investigated. The type of ha ndy phone used in this study was a personal handy phone system (PHS), which is a system developed in Japan that uses the NTT (Nippon Telephone and Tel egraph, Inc) telephone network service. The PHS has several advantages: hig h-speed data transmission, low power output, little electromagnetic interfe rence with medical devices, and easy locating of patients. In our system, p atients have a mobile computer (Toshiba, Libretto 50, Kawasaki, Japan) for data transmission control between an implanted controller and a host comput er (NEC, PC-9821V16) in the hospital. Information on the motor rotational a ngle (8 bits) and motor current (8 bits) of the implanted motor driven hear t is fed into the mobile computer from the implanted controller (Hitachi, H 8/532, Yokohama, Japan) according to 32-bit command codes from the host com puter. Motor current and motor rotational angle data from inside the body a re framed together by a control code (frame number and parity) for data err or checking and correcting at the receiving site, and the data are sent thr ough the PHS connection to the mobile computer. The host computer calculate s pump outflow and arterial pressure from the motor rotational angle and mo tor current values and displays the data in real-time waveforms. The result s of this study showed that accurate data on motor rotational angle and cur rent could be transmitted from the subjects while they were walking or driv ing a car to the host computer at a data transmission rate of 9600 bps. Thi s system is useful for remote monitoring of patients with an implanted arti ficial heart.