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Arrhythmias and intracardiac conduction after the arterial switch operation
L A Rhodes1, G Wernovsky, J F Keane
1Department of Cardiology, Children's Hospital, Boston, Mass.
Insights
The arterial switch operation for transposition of the great arteries preserves sinus node function and results in fewer rhythm disturbances compared to older baffle procedures. This anatomic correction offers a significant advantage for long-term cardiac health.
Area of Science:
- Cardiology
- Pediatric Cardiac Surgery
- Electrophysiology
Background:
- Intraatrial baffling procedures (Mustard, Senning) for transposition of the great arteries (TGA) are linked to high rates of cardiac arrhythmias.
- Atrial manipulation in these older TGA repairs can cause sinus node and atrial muscle trauma, leading to rhythm abnormalities.
- The arterial switch operation (ASO) involves minimal intraatrial manipulation, theoretically reducing arrhythmia incidence.
Purpose of the Study:
- To evaluate the incidence of cardiac arrhythmias after the arterial switch operation for TGA.
- To compare the electrophysiologic outcomes of ASO with historical data from intraatrial baffling procedures.
- To assess sinus node function and the prevalence of tachyarrhythmias post-ASO.
Main Methods:
- Retrospective review of 390 patients undergoing ASO between 1983 and 1990.
- Electrocardiograms and 24-hour Holter monitoring in 364 survivors at discharge and follow-up.
- Intracardiac electrophysiologic studies in 158 patients 6-12 months post-operation.
Main Results:
- Most patients maintained normal atrioventricular node function; 2% had first-degree, 0.7% second-degree, and 1.7% complete atrioventricular block (all with VSD).
- Sinus rhythm was present in 96% on ECG and 99% on Holter monitoring long-term.
- While atrial and ventricular ectopy were common, clinically significant tachyarrhythmias like supraventricular tachycardia (5% at follow-up) and atrial fibrillation were infrequent.
Conclusions:
- The arterial switch operation demonstrates significant advantages over atrial level correction for TGA regarding sinus node function preservation.
- ASO is associated with a low incidence of clinically significant tachyarrhythmias, supporting its role as the preferred surgical approach.
- Long-term electrophysiologic follow-up confirms the safety and efficacy of ASO in managing TGA.
Unlabelled:
Intraatrial baffling procedures such as the Mustard or Senning repair of transposition of the great arteries have been associated with a high incidence of cardiac arrhythmias. These abnormalities are thought to arise from trauma to the sinus node and atrial muscle during the procedure. In the arterial switch operation, there is little intraatrial manipulation other than the repair of the atrial septal defect. In theory, rhythm disturbances after the arterial switch operation should be less prevalent. From January 1, 1983, to December 31, 1990, 390 patients (230 with intact ventricular septum and 160 with a coexisting ventricular septal defect) underwent an arterial switch operation. Electrocardiograms and 24-hour Holter monitor studies were obtained in the 364 survivors at hospital discharge and during follow-up. Limited intracardiac electrophysiologic studies were performed 6 to 12 months after the operation.
Results:
Atrioventricular node function was preserved in most patients; seven patients (2%) had first-degree, two (0.7%) second-degree, and five (1.7%) had complete atrioventricular block (all with coexisting ventricular septal defect). All five patients with complete heart block received a permanent pacemaker. In those patients not having a permanent pacemaker, sinus rhythm was present in 96% on the surface electrocardiogram and 99% during 24-hour Holter monitor studies (1 month to 8.5 years, mean 2.1 years after the operation). Intracardiac electrophysiologic studies (n = 158) demonstrated normal corrected sinus node recovery times and AH intervals in 97% of patients. Atrial ectopy was present in 152 of 172 (81%) patients, with the majority (64%) of patients having only occasional premature beats without repetitive forms. Ventricular ectopy was a frequent finding during 24-hour monitoring. At hospital discharge 70% had ventricular ectopy; these values fell to 57% (in patients with intact ventricular septum) and 30% (in patients with a coexisting ventricular septal defect) at follow-up. In the early postoperative period, there were 25 episodes of supraventricular tachycardia (14 of which required therapy), 6 episodes of junctional ectopic tachycardia, and 9 episodes of ventricular tachycardia. The incidence of supraventricular tachycardia had fallen to 5% at follow-up, with no atrial flutter or fibrillation noted. Three patients had ventricular tachycardia on follow-up Holter studies. In summary, our results confirm the theoretical advantages of anatomic correction over atrial level correction of transposition of the great arteries with respect to preservation of sinus node function and low incidence of clinically significant tachyarrhythmias.