Purpose: To review the status of artificial sensors in cardiac pacemakers and the rationale for developing pacing systems that use multiple sensors.
Data Sources: Journal articles published between 1982 and 1993 indexed in MEDLINE using the keywords pacemakers, sensors, and rate-adaptive, as well as abstracts and articles in the authors' personal files.
Study Selection: Articles describing clinical experience with or clinical evaluation of cardiac pacing systems using multiple artificial sensors.
Data Synthesis: Artificial sensors were created to adjust pacing rate reliably in response to changes in levels of physical exertion for patients with sinoatrial disease in whom exercise heart rate response is inadequate (for example, chronotropic incompetence in sinoatrial disease). To achieve this, various artificial sensors were developed and many reports confirm improved exertional tolerance. More recently, sensors have assumed a greater role in cardiac pacemakers. For example, sensors are used to permit automatic adjustment of certain programmable pacemaker settings, such as the atrioventricular interval. In the future, they may also be used to maximize pacemaker longevity by automatically optimizing energy output (voltage, pulse width). No single sensor is ideal for all potential applications, and investigators have advocated using two or more sensors. Several pacemakers that use multiple sensors with different but complementary operating characteristics are already commercially available outside the United States. Although preliminary findings are encouraging, additional clinical experience with these pacemakers is needed to determine their ultimate role in clinical practice.
Conclusion: Simultaneous use of multiple complementary artificial sensors may permit development of cardiac pacemakers that operate more physiologically yet require less specialized medical follow-up.