Confinement of premature impulses in functional compartments of regions of the A-V conducting system.

Abstract

The local refractory periods of the multiple branches of the distal A-V conducting system progressively increase from proximal to distal, reaching a maximum a few millimetres proximal to the termination of a given tract of conducting tissue in muscle, and progressively decreasing beyond the point of maximum duration. The multiple areas of maximum local refractory periods function collectively to provide a limiting segment, or gate, which determines the functional refractory period of preparations of large segments of A-V conducting tissue. Artificial or natural changes in the refractory period of a single tract of conducting tissue alter the functional properties of such preparations. Reversal of the changes in, or ablations of, the single abnormal tracts of tissue reverses the changes in functional refractory period of the entire preparation. These observations may relate to the way in which local cardiac disease may cause re-entrant arrhythmias.