Sequential analysis of supraventricular arrhythmias and its value in the differentiation of irregular rhythms.

Distinctive electrocardiographic patterns for atrial fibrillation, sinus rhythm, and atrial extrasystoles and sinus arrhythmia were found by analysing the sequential distribution of cycle lengths. Sequential analysis demonstrated similarities between those arrhythmias, accounting for confusion between them, but it could also be used to demonstrate important differences. Utilizing information from both the frequency distribution and the sequential distribution of cycle lengths has improved the accuracy of computer identification of 20-sec arrhythmia recordings from 58.4 to 70.5%, when all supraventricular arrhythmias recorded on acute medical admissions were considered. It is suggested that such information will improve arrhythmia identification based on P wave analysis. From this analysis a classification of irregular rhythms has been proposed. An irregular rhythm may or may not be totally irregular. If there is lack of sequential dependency an arrhythmia should be described as nonperiodic. If there are distinct cycle lengths which are most frequent, the rhythm may be described as modal and there may thus be bimodal or trimodal rhythms which are irregular. Sinus rhythm with atrial extrasystoles may show a combination of these features. This can be described as a bimodal nonperiodic rhythm. If there is neither sequential dependency nor distinct modality the rhythm may be described as an irregular nonperiodic rhythm, e.g. some examples of atrial fibrillation. Sinus arrhythmia is an irregular periodic rhythm.