Insights into motion-based rate-responsive pacemaker algorithms and filters

Investigation of commercial pacemakers for comparing rate-response algorithms is complicated by device-specific, rate-response features. The present study examined common motion-based, rate-responsive pacing algorithms and filters using instrumentation which allowed direct comparison of these system components. Sixteen normal subjects performed exercise and daily living/artifact protocols. Signals from an accelerometer mounted inside a strapped-on pacemaker case and ECG were recorded. Heart rate was compared to accelerometer indicated rate for each algorithm (threshold crossing and integration), threshold (5-200 mg), and filter (1-4 and 15 Hz band-pass). Although, overall, the preferred algorithm rind filter depended upon the type of activity, for a threshold crossing algorithm, the 1-4 Hz filter gave better performance