[Is the concept of "jumping wave" still valid?].

Unlabelled: The concept of the "jumping wave" phenomenon, i.e. of the slow and difficult passage of activation fronts from one septal mass to the other through an "intraseptal barrier", is derived from experimental studies of the Mexican School of Electrovectorcardiography.

Objective: To confirm the existence of histologically bipartite interventricular septum and of the electric independence of both septal masses.

Methodology: We examined the histological characteristics of both septal masses in rat, canine, and human hearts. We also analyzed the morphological and chronological data of intracavitary records in the presence of different degree proximal blocks, comparing these findings with those obtained when peripheral blocks existed.

Results: We found a medial, longitudinal band between the two septal masses in animal as well as in human hearts. The analysis of intracavitary electric records confirmed a slow and difficult transmission of the activation fronts from one septal mass to the other, in the presence of proximal blocks and ventricular arrhythmias. Morphological and chronological changes of intraventricular complexes could not be explained if the septal activation process were of syncytial type.

Conclusions: Results of this study firmly support the validity of our approach to the septal activation process in the presence of ventricular conduction disorders and arrhythmias. This approach helps to detect the possible coexistence of dead septal tissue.