Electrophysiologic consequences of the arterial switch repair of d-transposition of the great arteries.

Electrophysiologic studies were performed at 12.7 +/- 4 months postoperatively in 20 patients who had the arterial switch repair at 1 to 120 days (mean 13 +/- 26 [SD]) for d-transposition of the great arteries. Preoperative electrocardiograms (ECGs) at rest revealed an ectopic atrial rhythm in one patient. Postoperative rest ECGs revealed transient postoperative ectopic atrial or junctional rhythms in two patients, intermittent ectopic atrial rhythms in two and right bundle branch block in nine with a normal QRS axis. In addition, ambulatory monitor recordings revealed infrequent premature ventricular complexes in five patients. Catheter endocardial mapping revealed sinus rhythm in 18 patients and ectopic atrial rhythm in 1 patient. Atrial activation after the switch repair was comparable with normal atrial activation. Activation of all low atrial sites was significantly earlier after the switch repair than after the Mustard repair. Mild abnormalities of sinus node function were present and consisted of slight prolongation of corrected sinus node recovery time in six patients and slightly increased sinoatrial conduction time in four. The ratio of sinus node recovery time to sinus cycle length was normal in all 20 patients. Atrial effective and functional refractory periods were normal in all patients and no atrial arrhythmias could be induced by programmed stimulation. Atrioventricular (AV) node conduction was excellent with normal AV node effective and functional refractory periods. The only electrophysiologic abnormality of His-Purkinje function was distal right bundle branch block in nine patients. Programmed stimulation of the ventricle produced repetitive ventricular responses in four patients: bundle branch reentry in three and intraventricular reentry in one.(ABSTRACT TRUNCATED AT 250 WORDS)