An experimental contribution to the concept of "jumping wave" phenomenon in the interventricular septum.
OBJECTIVE
The purpose of this study was to evaluate the existence of a histologically bipartite interventricular septum and the electrical independence of both septal masses, as well as to understand the changes of septal activation fronts in the presence of bundle branch blocks.


METHODS
We examined the histological characteristics of both septal masses in 12 canine hearts. Furthermore, in another 11 anesthetized dog hearts, we analyzed morphological and chronological data of intraseptal records with normal activation and in the presence of proximal blocks.


RESULTS
A histological discontinuity between the two septal masses in canine hearts seems to exist. Analysis of intraseptal and intracavitary electrical records confirmed slow transmission of the activation fronts from one septal mass to the other when proximal blocks were present. Morphological and chronological changes of the intracavitary complexes agree with the "jumping wave" phenomenon theory.


CONCLUSIONS
These results support the validity of this approach to the activation of both septal masses and explain the chronological and morphological changes of the intracavitary records in the presence of ventricular blocks. In addition, this approach is a useful tool to detect the possible coexistence of dead septal tissue.
Medrano
Gustavo A
GA
Instituto Nacional de Cardiologia Ignacio Chávez INCICH, Juan Badiano No. 1, Col. Sección XVI, Tlalpan, 14080 México, D.F.
de Micheli
Alfredo
A
Aranda
Alberto
A
Iturralde
Pedro
P
Chávez Domínguez
Rafael
R
D000818:Animals; D004285:Dogs; D004594:Electrophysiology; D006346:Heart Septum / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans