Physiopathological and diagnostic hypotheses in peripheral block

Delays and conduction blocks may occur in Purkinje fibers, junctions and muscular cells. Since such blocks may take place everywhere in the ventricles and not only in the free walls, we prefer to use the term peripheral instead of parietal block. The electrophysiologic problems connected with such blocks are discussed. The localization of the ventricle affected by the block is usually simple using VCG recording and is based on the orientation of terminal vectors. It is more difficult to recognize the ventricular walls affected by the block, the intraparietal localization and the source of the block: Purkinje fibers, junctions or muscular fibers. We maintain the concept that peripheral blocks alter not only the terminal phases of ventricular depolarization, but sometimes also the initial ones, in that the Purkinje-junction-muscular fibers system can be damaged in the septum with the major conduction pathways remaining intact. Several discrepancies found between the prescence of electric patterns of septal necrosis and autopsy data may be explained by peripheral blocks localized in the left septum.