The History of Atrial Fibrillation: The Last 100 Years

Eric N. Prystowsky, M.D.

Disclosures

J Cardiovasc Electrophysiol. 2008;19(6):575-582. 

In This Article

Reentry Versus Automaticity

The earlier studies of Sir Thomas Lewis suggested reentry as the likely mechanism of atrial fibrillation. However, Scherf[12] performed a series of experiments that suggested the mechanism of atrial fibrillation was due to an ectopic focus. In one such study he injected aconitine in canine atria, and this led to rapid excitation with the appearance of atrial fibrillation. When he produced local cooling of the area the arrhythmia stopped and restarted after discontinuation of the cooling. From these types of studies he concluded that atrial fibrillation was caused by a rapid stimulus rather than reentry. He made an important observation regarding the subsequent conduction of the rapidly firing focus that he considered "fibrillatory conduction." He stated that "as the impulses… move into the larger mass of auricular muscle, islands of refractory tissue appear which cause a weaving and interweaving of the contraction process that is characteristic of fibrillation." Thus, the subsequent possible reentry waves of excitation are not the cause of the arrhythmia but were a concomitant feature of atrial fibrillation. This ectopic focus theory appears quite plausible now, especially with our modern understanding of atrial fibrillation, but it was markedly overshadowed by the observations of Moe et al.[13,14]

In a canine atrial preparation, rapid atrial pacing as well as a background of vagal stimulation were used to induce persistent atrial fibrillation.[13] During atrial fibrillation, the appendage was excluded with a clamp; when the atrial pacing was discontinued, the atrial fibrillation was no longer apparent in the appendage but the rest of the atria continued to fibrillate. From these experiments, Moe concluded that reentry was the most likely mechanism for atrial fibrillation. He stated that "the grossly irregular wave front becomes fractionated as it divides about islets or strands of refractory tissues, and each of the daughter wavelets may now be considered as independent offspring… Fully developed fibrillation would then be a state in which many such randomly wandering wavelets coexist." This became the multiple wavelet hypothesis for atrial fibrillation and carried not only the day but the subsequent decades until the observations of Haissaguerre et al.,[15] as described later. While supporting reentry as the major mechanism of atrial fibrillation, Moe et al.[13] also concluded that the irregular activation of the atria could be produced by several factors including a single rapidly discharging ectopic focus, multiple rapidly discharging foci, or rapidly circulating circus movement.

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