Abstract: An improved bio-medical telemetry apparatus for programming an implanted medical device includes a large substantially planar and concentrically wound first telemetry coil. The coil is disposed inside a thin flexible housing including layers of insulative materials to prevent electrical contact between loops of the first telemetry coil and to hold the first telemetry coil formed shape in place. The apparatus further includes a communication lead coupled to the first telemetry coil for communicating with a medical device programmer. During a telemetry session the first telemetry coil including the flexible housing is disposed at a posterior location of the torso and an implanted medical device disposed subcutaneously on an anterior location of the torso. During programming the first telemetry coil is inductively coupled to the implanted medical device for wireless data communication with the implanted medical device.

Abstract: An electronic switching circuit for use in a demand-type cardiac pacer for (1) allowing the amplitude of the stimulating pulses to be selected, (2) ensuring a high input impedance for the heartbeat sensing amplifier, and (3) ensuring a low recovery time following the generation of a pacer pulse. Disposed between the heart contacting electrodes and the sensing amplifier is an electronic switch which is closed during a predetermined period (the sensing interval), but which is opened when the pulse generator is producing a pacer pulse. Thus, the sensing amplifier is shielded from receiving the high voltage surge occasioned by the application of a pacer pulse to the heart. Similarly, an electronic switching device is interposed between the pulse generator and the heart contacting electrodes, which device is closed during a pacing interval, but open during the aforesaid sensing interval, thus isolating the sensing amplifier from the pacer circuitry.