COMPARISON OF EXTERNALLY STRAPPED VERSUS IMPLANTED ACCELEROMETER-BASED OR VIBRATION-BASED RATE-ADAPTIVE PACEMAKERS DURING VARIOUS PHYSICAL ACTIVITIES

The ability of externally strapped accelerometer- (Excel [Cardiac Pace makers, Inc.]) and vibration-based (Activitrax [Medtronic, Inc.]) rate adaptive pacemakers to reproduce the rate response of the same implan ted devices with identical programming was evaluated in ten patients b y ambulatory Holt er monitoring. The resting and postexercise external pacemaker rates closely resembled those of the respective implanted d evices. During short bursts and more prolonged exercise, both types of strapped-on devices underestimated maximal implanted pacemaker rate r esponse by 4%-10% when programmed to nominal rate adaptive settings. S tudies evaluating chronotropic responses from either type of externall y strapped activity sensor appear valid, provided the modest attenuati on in maximal rate increase by this method is appreciated.