Chaotic atrial rhythm

Thirty-one cases of what is believed to be an autonomous arrhythmia, called chaotic atrial rhythm, have been reviewed and analyzed. The main diagnostic criteria of this arrhythmia are: a) the presence of clearly distinguishable P waves, b) presence of an isoelectric baseline between the P waves, c) constantly changing configuration of the P waves, and d) a constantly changing P-P interval. The incidence of chaotic atrial rhythm was 0.4% of 8000 patients who had electrocardiograms taken in the Maimonides Medical Center during the year 1969. It occurs predominantly in old people. The most frequently observed associated factors were arteriosclerotic heart disease and bronchopulmonary disease (chronic and acute), but multiple other factors can be involved. Digitalis toxicity seems infrequent. The transition of chaotic atrial rhythm to atrial fibrillation, often reported in the past, appears to be rare. The prognosis of this arrhythmia per se seems to be relatively benign in most of the cases. The treatment has not yet been codified and appears to be unnecessary in most cases. The mechanism of chaotic atrial rhythm is obscure, but evidence is presented to suggest that it might be an accelerated and extreme form of a wandering pacemaker associated with atrial premature contractions.