Case Studies on the Effect of Exercise and Hot Water Submersion on Intracardiac Temperature and the Performance of a Pacemaker Which Varies Pacing Rate Based on Temperature

Abstract

The effectiveness of using blood temperature change as an indicator to automatically vary heart rate physiologically was evaluated in 3 patients implanted with Model Sensor Kelvin 500 (Cook Pacemaker Corporation, Leechburg, PA, USA) pacemakers. Each patient performed two block-randomized treadmill exercise tests: one while programmed for temperature-based, rate-modulated pacing and the other while programmed without rate modulation. In 1 pacemaker patient and 4 volunteers, heart rates were recorded during exposure to a hot water bath.
Blood temperature measured at 10sec intervals and pacing rate measured at 1min intervals were telemetered to a diagnostic programmer and data collector for storage and transfer to a computer. Observation comments and EGG-derived heart rates were manually recorded.
The temperature-based pacemaker was shown to respond promptly not only to physical exertion but also to emotionally caused stress and submersion in a hot bath. These events cause increased heart rate in the normal heart. Using a suitable algorithm to process the measurement of blood temperature, it was possible to produce appropriate pacing rates in paced patients.