His bundle recordings using epicardial pacing wires: a new technique

His bundle electrograms were recorded from the epicardial surface of the heart of nine dogs using temporary pacing electrodes. Simultaneous His bundle activity was recorded by the standard endocardial catheter technique. There was a close correlation between the AH times (r = 0.93) and HV times (r = 0.96) using both techniques. This new technique for studying His bundle activity is simple, requires no additional dissection during the performance of open heart surgery, and should be of value in diagnosing conduction system disturbances occurring in the perioperative period.