Arrhythmias before and after anatomic correction of transposition of the great arteries.

Cardiac rhythm has been evaluated using 24 hour ambulatory electrocardiographic (ECG) recordings in 92 survivors of anatomic correction of transposition of the great arteries. A low incidence of arrhythmias was found in preoperative recordings made in 41 patients. Thirty-four (83%) patients showed sinus rhythm exclusively; one (2.4%) patient had supraventricular premature beats and one (2.4%) paroxysmal atrial fibrillation. Six patients (14.6%) had ventricular arrhythmias, five (12.2%) with modified Lown grade 1 ventricular premature beats and one (2.4%) with a modified Lown grade 5 arrhythmia. The incidence of arrhythmias was unchanged after a first stage operation consisting of banding of the pulmonary artery with or without insertion of a systemic to pulmonary shunt. During a mean 3.1 year follow-up, there have been no cases of arrhythmic death or symptomatic arrhythmias requiring treatment. Postoperative recordings in 40 patients have shown a low incidence of important arrhythmias with 62% having recordings free from arrhythmias. There was an increase in the incidence of infrequent supraventricular premature beats from 4.9% preoperatively to 23% postoperatively (p less than 0.05), with no significant change in the incidence of ventricular arrhythmias. One patient has acquired complete heart block but all others had sinus rhythm postoperatively. Preoperative arrhythmias are uncommon in patients with transposition of the great arteries and are similar to those described in normal children. The incidence of important arrhythmias after anatomic correction is low during the medium-term period of follow-up. Further longitudinal studies will be required to determine whether this promising result is maintained.