May 1, 1985

An "account" of digitalis and atrial fibrillation

Journal of the American College of Cardiology
F L Meijler

Abstract

This review deals with the mechanisms by which digitalis exerts its "opium-like" action on the ventricular rate in patients with atrial fibrillation. To understand the effect of digitalis on ventricular rate and rhythm, it is essential to learn more about the basic electrophysiologic principles responsible for: atrial fibrillation as such, and the scaling function of the atrioventricular (AV) node-His system. It may be assumed that during atrial fibrillation, the atrial excitatory process results in randomly spaced impulses that reach the AV junction from random directions with random strength. The refractory period of and concealed conduction in the AV node enable the AV conduction system to scale down the shower of atrial impulses to a random ventricular response with a considerably lower rate. Digitalis decreases the ventricular rate through two synergistic pharmacologic actions: digitalis increases the refractory period of the AV node, and digitalis decreases the refractory period of the atrial myocardium through a direct and indirect effect (vagotonic and vagomimetic). A decrease in the refractory period of the atrial myocardium results in more atrial impulses reaching the AV junction in a given unit of time. More atrial i...Continue Reading

  • References47
  • Citations26

Mentioned in this Paper

Sinoatrial Node
Exertion
Left Ventricular Structure
Left Bundle Branch of His
Myocardial Stunning
Digitalis preparation
Feedback - System Communication
Right Atrial Structure
Papapver somniferum, opium, dried latex of poppy
Atrial Fibrillation

About this Paper

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