Activity controlled cardiac pacemakers during stairwalking: a comparison of accelerometer with vibration guided devices and with sinus rate.

Activity controlled pacemakers are the most widely used rate adaptive systems. We studied second-generation activity controlled systems (accelerometer) in 21 patients with such an accelerometer controlled system implanted during walking level and stairs. We compared them to the rate of vibration controlled, first-generation activity pacemakers and to the sinus rate of a healthy control group. A metronome directed the speed during walking and climbing stairs at 92, 108, and 120 steps/min. At 92 steps/min, the new accelerometer controlled systems showed a significant (P < or = 0.001) pacing rate increase from 107 +/- 8 beats/min during walking level to 124 +/- 8 beats/min during climbing stairs, and a significant decrease to 105 +/- 12 beats/min during walking downstairs. In contrast, first-generation activity controlled pacemakers showed a less physiological rate behavior with higher pacing rate (113 +/- 7 beats/min) walking downstairs than walking upstairs (97 +/- 9). For everyday activities at normal walking speed, accelerometer controlled pacemakers show a more physiological rate behavior than first-generation pacemakers, but they lose this physiological response with faster walking.