A new motion responsive pacemaker: first clinical experience with an acceleration sensor pacemaker.

A new accelerometer-based adaptive rate pacemaker (EXCEL VR) was evaluated to investigate its behavior at nominal settings during treadmill exercise testing and postural changes. Eight patients with sinus rhythm were selected to compare intrinsic heart rate to sensor mediated rate. Throughout exercise treadmill testing, changes in the sensor mediated rate closely paralleled actual physiological changes. The Pearson product moment correlation of pacing rate with sinus frequency, calculated for all patients, was r = 0.82 (P = 0.001). Change in the patient's physical position resulted in immediate change in sensor rate, which corresponded appropriately to the type of position change and activity level. Average (+/- SD) pacing rate was 62.4 +/- 2.7 beats/min supine; 67 +/- 3.8 beats/min sitting; 69.8 +/- 6.4 beats/min standing; 81.6 +/- 8.7 beats/min slow walking; and 96.8 +/- 1.3 beats/min fast walking. After 4 minutes of recovery, the average pacing rate dropped to 65 +/- 3 beats/min. The interaction between the accelerometer and the pulse generator at nominal settings was accurate and infrequently required the use of its many programming options. The accelerometer sensor and pulse generator algorithm in this device during postural change and exercise resulted in physiological-like changes in sensor mediated heart rate.