Lessons from comparative studies of atrial fibrillation in dog, man and horse

Abstract

Since its first description in 1903 by Hering, the irregularity of the heart beat has been the most striking characteristic of atrial fibrillation and has been subject of many studies. To quote Selzer, "Atrial fibrillation is the grandfather of cardiac arrhythmias." It is an arrhythmia that 1) often complicates rheumatic heart disease, 2) is a frequent complication of coronary heart disease and diabetes, and 3) may accompany hyperthyroidism. Moe has considerably contributed to our understanding of atrial fibrillation. He, like Burn, made it plausible that fibrillation arises because the electrical activity generated by the fibers excites one another. The multiple wavelet hypothesis still seems the best explanation for what we observe electrophysiologically during (atrial) fibrillation. Our own observationsis using signal analysis techniques in experimental ventricular fibrillation support the ideas formulated by Moe nearly 25 years earlier. Nevertheless, the true pathophysiologic mechanisms are basically unknown. Similarly the role of the AV node-His conduction system in atrial fibrillation is not fully understood. The purpose of this paper is to present observations obtained during comparative studies in dogs, humans, and horses with atrial fibrillation that may prove helpful in explaining the irregular pattern of the ventricular rhythm and may also contribute to a more rational therapy of atrial fibrillation.