Segmental atrial fibrillation resulting in chronic atrial dissociation. A case report

Atrial arrhythmias are diagnosed on the basis of the analysis of P wave morphology, timing and rate, the surface electrocardiogram, and intracardiac recordings. Recent intracardiac studies have demonstrated dissimilar atrial rhythms with direct intra-atrial recordings, the former otherwise not evident on the surface ECG (Zipes et al. 1972, Wu et al. 1975, Friedman et al. 1974, Gomes et al. 1981). This paper reports the electrocardiographic diagnosis of atrial dissociation made on the surface electrocardiogram. The findings suggest the following: (1) That sinus rhythm exists, with the dominant sinus rhythm depolarizing the major portion of the right as well as the left atrium; (2) Atrial fibrillation localized specifically to lead III, and at times to leads III and AVL, on the surface electrocardiogram; and (3) Intraesophageal recordings and echocardiography revealed an area of the posterior right and left atria that had wall motion abnormalities and electrical activity compatible with those of atrial fibrillation.