Microelectrode Studies on Concealment of Multiple Premature Atrial Responses

Abstract

Experiments employing microelectrodes to record from single cells within the AV node and ventricular specialized conduction system during conduction of serially evoked premature atrial responses have demonstrated AV conduction delays and block within both the AV node and ventricular specialized conduction system. The rapid decrease in functional refractory period of fibers within the ventricular specialized conduction system, following a decrease in preceding cycle length, resulted in block within the AV node of most serially concealed premature atrial responses. A one-millisecond change in the time of excitation of a premature atrial response could determine whether block or conduction occurred in the AV node.