First steps toward a pacing algorithm for vasovagal syncope.

Vasovagal syncope is commonly associated with an intermediate fall in heart rate. Consequently, it seemed possible that a pacemaker algorithm designed to detect intermediate heart rate falls might prove useful as a diagnostic tool to initiate pacing therapy. Subsequent experience suggests that with such an approach it is still difficult to avoid "false-positive" detection of physiologic heart rate slowing (e.g., sleep). On the other hand, findings from several reports suggest that high rate pacing using this algorithm has proved clinically effective.