Longitudinal dissociation in the His bundle. Bundle branch block due to asynchronous conduction within the His bundle in man.

This report presents electrophysiological data in 27 patients (out of a series of 110) which suggest longitudinal disso- ciation in the His Bundle (BH).Twenty-five patients showed left bun- dle branch block (LBBB) which was rate related in three and two had isolated left axis deviation (LAD) with narrow QRS complexes.BH recordings were performed via the right heart, and in each patient the same electrode catheter was used for stimulation of the BH at different sites.The H-V time was prolonged (range 50-70 msec, mean 59) in all 22 patients with constant LBBB, in one of the three of the rate related LBBB, and in one of the two with isolated LAD; and remained unchanged throughout.In all 25 patients with LBBB prox- imal BH stimulation exhibited QRST complexes identical to those ON THE BASIS of their extensive histological studies, James and Sherf have recently reported that the longitudinal separation of Purkinje strands by collagen along with specialized nature of intercellular junctions within each strand form an anatomic basis for longitudinal separation of conduction within the normal His bundle.'These investiga- tors have proposed the concept of "sinoventricular conduc- tion" which implies that the individual components of the