Dysrhythmias following the Mustard and Senning operation for transposition of the great arteries

The prevalence and nature of late dysrhythmias following operative repair of transposition of the great arteries were evaluated in 32 children using pre- and postoperative standard electrocardiograms and postoperative Holter monitoring. The Mustard procedure was performed in 17 patients, the Senning procedure in 15 patients. The mean age at operation was 40 +/- 35 months in the Mustard and 9 +/- 6 months in the Senning group. The mean interval between operation and Holter monitoring 7 +/- 2 years in the Mustard and 1.6 +/- 1 years in the Senning group. All patients had sinus rhythm preoperatively. Following operation, the incidence of sinus rhythm increased from 59% in the Mustard and 87% in the Senning group in the first postoperative week to 76% in the Mustard and 100% in the Senning group at the end of follow-up (mean 4.6 +/- 3.5 years). Holter monitoring revealed dysrhythmias or conduction abnormalities in 12 patients (9 Mustard, 3 Senning). A permanent pacemaker had to be inserted in 2 Mustard patients because of complete atrioventricular block and sinus bradycardia with sinus arrest, respectively. Results indicate a prevalence of late postoperative dysrhythmias of 20% in the Senning and of 59% in the Mustard group (p less than 0.05). However, the significantly longer mean follow-up period of the Mustard group precludes a direct comparison between the 2 types of repair.