A COMPARATIVE-STUDY OF ACTIVITY AND DUAL SENSOR - ACTIVITY AND MINUTEVENTILATION PACING RESPONSES TO ASCENDING AND DESCENDING STAIRS

Previous studies with activity-based rate adaptive pacemakers have sho wn a somewhat paradoxical response when comparing ascending stairs to descending stairs. The objective of this investigation was to measure dual-sensor rate response provided by activity and minute ventilation (MV) compared with activity alone, and with a control group, during as cending and descending stairs. For dual sensor mode, measured mean pea k pacing rate with 72 (92) steps per minute was 111 +/- 13 beats/min ( 124 +/- 14 beats/min) ascending stairs and 81 +/- 7 beats/min (97 +/- 13 beats/min) for descending. For activity mode alone, mean peak pacin g rate was 90 +/- 12 beats/min (108 +/- 19 beats/min) ascending stairs and 97 +/- 12 beats/min (123 +/- 17 beats/min) descending. The mean p eak control group heart rate ascending stairs for a step rate of 72 (9 2) steps/min were 116 +/- 11 beats/min (127 +/- 14 beats/min) ascendin g stairs and for descending 89 +/- 12 beats/min (95 +/- 11 beats/min). While for dual sensor controlled pacing there was a significant diffe rence for ascending and descending stairs at both step rates, there wa s no difference between going upstairs and downstairs for activity mod e alone. Rates with dual sensor did not significantly differ from resp ective rates of the control group. The mean correlation coefficient be tween MV and paced rate was 0.85. Pacing heart rates delivered by the dual sensor mode were appropriate for ascending and descending stairs. In contrast to activity mode alone, the peak heart rates for dual sen sor mode are higher during ascending than during descending stairs.