DEVELOPMENT OF A NEW MYOSTIMULATOR - FIRST EXPERIENCE WITH THE MID DISTANCE IMPLANT RF-TELEMETRY

Background: Wireless data transfer from an implant, e.g. cardio- or myostimulators to an external programming device, is common and valuable to adjust stimulation parameters with a device distance of some centimeters. Thus the initiator of the communication is always the external device. Objectives: In order to overcome this short distance limitation and design a myostimulator with the ability of implant-initialized communication, a RF based telemetry module was utilized. A communication line was to develop and test in vivo. Materials and Methods: The myostimulator consists of the standard components of two microcontrollers and a RF telemetry module (433 MHz band). One controller is responsible for myostimulation tasks, the other for measurements and communication tasks. Microcontroller driven external transceiver was controlled via PC. In vivo examinations were carried out in n=4 African Boor goats by implanting the device subcutaneously. Results: The communication protocol was programmed to be packet orientated and failure recognizing. Failed packages could be requested again. Both devices, the external and the implanted one, were able to transmit a device calling sequence thus initializing communication. Both devices listen periodically to the calling sequence. In vivo transmission distance was between 3 and 5 meters. Gross data transfer rate was between 6000 and 8000 bits per second. Conclusions: By means of the implant-initialized, mid distance telemetry, important subject relevant information could be collected and transmitted by the implant. An external, wearable receiver like a PDA could inform subject and bridge data between the implant and others like the consulting physician and a medical center.