Abstract
The presence of supernormal excitation was confirmed repeatedly in all 10 cases following cardiac surgery.
By the stimulation of minimum subthreshold impulses capable of originating ventricular responses, the supernormal excitation was limited only at the descending limb of T wave. The duration lasted only 0.02 sec at the minimum subthreshold stimuli.
But the higher subthreshold stimuli produced the longer duration of supernormal excitation phase. The duration of the excitation phase prolonged towards the following R wave, hardly extending towards the preceding R wave, with the increase of subthreshold stimuli.
