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Activity‐Responsive Pacing Produces Long‐Term Heart Rate Variability
Author(s) -
RAJ SATISH R.,
ROACH DANIEL E.,
KOSHMAN MARYLOU,
SHELDON ROBERT S.
Publication year - 2004
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.2004.03342.x
Subject(s) - heart rate variability , medicine , cardiology , heart rate , term (time) , ambulatory , cardiac pacing , poincaré plot , rr interval , physics , blood pressure , quantum mechanics
Long‐term heart rate variability (HRV) measures, including the standard deviation of means of successive 5‐minute epochs of R‐R interval intervals (SDANN) and the power law slope (β), are important prognostic measures, yet their physiologic basis is unknown. We tested the hypothesis that long‐term HRV arises from physical activity in a randomized cross‐over study in patients with rate‐responsive pacemakers. Methods and Results: Ten patients with complete heart block and dual‐chamber pacemakers underwent 24‐hour periods of ambulatory ECG in each of three pacing modes: atrially tracked, fixed‐rate, and rate‐responsive pacing. SDANN, ultralow frequency (ULF; frequencies <0.0033 Hz), and β slope were calculated; and high‐frequency power and root mean square of consecutive normal R‐R intervals (rMSSD) were calculated as measures of short‐term HRV, which have autonomic origins. Long‐term HRV measures were similar with atrially tracked and rate‐responsive pacing and were much greater than in fixed‐rate pacing (SDANN P = 0.0001; ULF P = 0.0001; β slope P = 0.0002). Short‐term HRV measures were similarly low in fixed‐rate and rate‐responsive pacing (P = NS) and were significantly lower than with atrially tracked pacing (P = 0.0034). Conclusion: Rate‐responsive pacing reproduces long‐term, but not short‐term, measures of HRV, suggesting that they may be markers of heart rate responses to patient activity. (J Cardiovasc Electrophysiol, Vol. 15, pp. 179‐183, February 2004)