Arrhythmias after the Mustard operation for transposition of the great arteries: a long-term study.

This study presents follow-up data on 95 patients with transposition of the great arteries who underwent a Mustard intraatrial baffle operation. The patients were followed up serially by means of scalar electrocardiograms and 24 hour Holter monitoring studies. The latter study was effective in documenting abnormal rhythm patterns when the standard electrocardiogram was within normal limits. Twenty percent of the patients had atrial arrhythmias at the time of hospital discharge. new rhythm disturbances were recognized during each year of follow-up; 75% of the patients had atrial rhythm disorders by the sixth year. Slow junctional rhythm was the most common rhythm disturbance found. Complete heart block did not occur. Supraventricular tachycardia occurred within the context of the tachycardia/bradycardia syndrome in 8 of 10 patients, and in all it was documented after hospital discharge. The incidence of sudden death in this series was 3%. Six of the patients have had pacemaker insertions and there have been no deaths among these individuals. It was observed that the slow atrial or junctional rhythms that appeared after intraatrial correction of transposition of the great arteries rarely progressed to life-threatening rhythm disorders in childhood or adolescence, but the prognosis in adult life remains unknown. The three deaths in the series occurred in patients with a history of supraventricular tachyarrhythmias. Elimination of arrhythmias caused by extensive intraatrial surgery is one of the potential advantages of the arterial switch operation for correction of transposition of the great arteries.