Analysis of the re-entrant beat in response to the ventricular extrastimulation. Using 10 polar electrode catheter.

The study of re-entry phenomenon during the right ventricular extrastimulus method was performed on 22 patients using 10 polar electrode catheter. Two to 4 spikes from the specialized conduction system were recorded in response to the premature extrastimulation (S2). By using this catheter, the catheter position was defined more clearly than the other reports. From the patterns and sequence of spikes in response to S2, the routes of impulse propagation were studied. In 17 cases whose patterns of spikes were different from those of antegrade conduction, the impulse from S2 seemed to be retrogradely conducted via the left bundle branch (LBB) to the branching portion and thereafter conducted bidirectionally both to His bundle (HB) and the right bundle branch (RBB) (HPS re-entry). In 6 cases whose patterns of spikes were similar to those of antegrade conduction, the impulse from S2 was retrogradely conducted via RBB to HB and turned in some portion above HB and antegradely traveled to the ventricle. In one case who was diagnosed as concealed WPW syndrome, the pattern of spikes showed 2 types of re-entry as described above. The mechanism of the ventricular re-entry was able to be classified into 2 types from the patterns and sequence of spikes in response to S2.