Keizo Yoshimura

Cardiac pacemaker regulated by respiratory rate and blood temperature.

A new method using respiratory rate and temperature as the guides for optimal pacing is proposed. A pacemaker was fabricated which senses these two parameters simultaneously. The pacemaker functions by calculating the cardiac rate, which would he derived from the respiratory rate and the blood temperature. The higher of the two rates is adopted as the cardiac pacing rate, i.e., at which stimuli will be delivered. The operation was tested in a mongrel dog with complete atrioventricular block. After the induction of anesthesia, a thermistor temperature probe was inserted into right atrium and a respiratory rate sensor was attached around the chest. After administration of a pyrogenic drug, both respiratory rate and blood temperature increased. The pacing rate was increased from 178 beats/minute(bpm) at 36.4°C. blood temperature, and 26.5 acts/minute(apm), respiratory rate, to 233 bpm at 40.1°C and 40.0 apm. Cardiac output was increased from 2.25 liters/minute(1/pm) at the beginning to 2.50 l/pm at maximum. The transition of the guide from respiratory rate to temperature was observed at about 38°C.

A heart-rate-responsive diaphragm pacemaker

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Telemetry system for heart-rate and blood temperature using a microcomputer

A radio-telemetry system using a microcomputer has been constructed to measure both the heart-rate (HR) and right atrial blood-temperature in dogs. The telemeter incorporates a thermistor temperature probe, which allows blood-temperature measurements in the range of 35 degrees-42 degrees C with an available resolution of +/- 0.02 degree C. The output of the receiver is connected to active filters, a frequency counter and an HR meter, and finally to a microcomputer, through an appropriate interface circuit, for data linearization and storage.

Microcomputer-based cardiac pacemaker-control system through blood temperature

A microcomputer-based temperature-sensitive cardiac pacemaker system and some preliminary experiments are described. The system consists of a microcomputer, a twin 5 in floppy disk unit, expansion and interface units, a visual display unit and a printer. It senses the blood temperature in the right atrium, determines the pacing rate and supplies the heart with stimulating pulses. System-heart interfacing is performed by the separate pacing and sensing units which communicate with the computer via a peripheral interface IC in an expansion unit. The pacing rate is determined by software, rather than a combination of hardware elements. The temperature response time of the system, from 25 degrees C to 40 degrees C is about 26 s, and this would seem to be satisfactory given that smaller and slower changes in blood temperature are normal.