Atrial capture detection with endocardial electrodes.

A new method of evoked response detection, previously demonstrated in the ventricle, has been studied in the atrium at the time of routine pacemaker implant in 16 patients. The atrial evoked response was readily detectable in all patients due to excellent recovery from poststimulus polarization. In six patients, as experimental threshold-tracking pacemaker was used to automatically verify atrial capture and to generate strength-duration curves. It is concluded that this pacing technique is both simple and reliable, and that automatic atrial threshold tracking is feasible.