[Motion of the interventricular septum in patients with right intraventricular electric stimulators....

An echo- and vectorcardiographic study had been performed in order to analyze the motion of the interventricular septum (IVS) in thirty-six patients with chronic pacing at the apex of the right ventricle. As this pattern has been reported as just like that of LBBB, five patients with LBBB have been studied as well, with transient pacing. As far as the first group, in 25 P. IVS moves, both during spontaneous activity and pacing, like in normal subjects; in 8 P. the records were questionable; in 3 P. IVS moves liek in LBBB. The group of 5 P. with LBBB shows paradoxical motion of IVS both before and during pacing. In vectorcardiograms, the initial ventricular vectors (from 0 to 30 msec) are upward, backward and rightward oriented, in 33 of the first group's 36 P. The second group of 5 LBBB failed to show a costant pattern. The possible electrophysiologic hypotheses, about genesis of these patterns, are discussed.