Critical analysis of sensors for physiological responsive pacing.

Physiological responsive pacing includes the application of sensors to measure physiologic variables, which in turn are used to control pacemaker rate. Six such systems are evaluated based on a comparison of (1) speed of response, (2) sensor reliability, and (3) system specificity. Although there is not a clear-cut solution, and every system has some weaknesses, several sensors seem more feasible than others. Much research remains to be done, and the indications and patient benefits must be established.