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Rhythm and conduction disturbances in isolated, congenitally corrected transposition of the great arteries
Insights
Patients with congenitally corrected transposition of the great arteries often develop conduction disturbances, including atrioventricular block and ventricular arrhythmias, necessitating careful cardiac monitoring.
Area of Science:
- Cardiology
- Electrophysiology
- Congenital Heart Disease
Background:
- Congenitally corrected transposition of the great arteries (ccTGA) is a complex congenital heart defect.
- Rhythm and conduction disturbances are known complications, but their incidence and specific types require further elucidation.
Purpose of the Study:
- To investigate the incidence and characteristics of cardiac rhythm and conduction abnormalities in patients with ccTGA.
- To correlate clinical presentation, electrophysiologic findings, and histological data in this patient cohort.
Main Methods:
- Study included 17 patients (11 male, 6 female) with ccTGA, aged 5-54 years.
- Methods included surface electrocardiography, 24-hour Holter monitoring, and electrophysiologic studies.
- Histologic examination of the conduction system was performed in one patient with sudden death and complete atrioventricular block.
Main Results:
- Five patients (29%) developed complete atrioventricular (AV) block, often preceded by first- or second-degree AV block.
- Electrophysiologic studies identified AV block at supra-Hisian or proximal His bundle levels; histology revealed His bundle disruption in one case.
- Ventricular arrhythmias were common on Holter monitoring; supraventricular tachycardia was observed in two patients, linked to accessory pathways or dual AV nodal pathways.
Conclusions:
- Patients with ccTGA have a high incidence of significant conduction system disease, including progressive AV block and ventricular arrhythmias.
- Electrophysiologic assessment and histological examination are crucial for understanding the mechanisms of these disturbances.
- Long-term cardiac monitoring is essential for managing patients with ccTGA due to the risk of arrhythmias and sudden death.
Abstract:
The incidence and types of rhythm and conduction disturbances in 11 male and 6 female patients with congenitally corrected transposition of the great arteries and no other intrinsic complicating anomalies were studied. Patient age ranged from 5 to 54 years; follow-up ranged from 5 to 37 years. Surface electrocardiograms were recorded in each patient; 15 also underwent 24-hour Holter monitoring and 10 underwent electrophysiologic study. The conduction system of a 54-year-old woman who died suddenly, with complete atrioventricular (AV) block since age 30 years, was studied by serial histologic sections. Fifteen patients were asymptomatic and 2 reported repeated episodes of palpitation since childhood. Ten patients presented with a normal PR interval and 2 with first-degree AV block (12%). Five patients had complete AV block (29%), but none had had it at birth; first- and second-degree AV block preceded complete AV block in 2 patients. The morphologic pattern and duration of QRS suggested a junctional rhythm in 4 patients and an idioventricular pacemaker in 1 patient. Electrophysiologic studies confirmed that the complete AV block site was supra-Hisian in 2 patients and proximal to the His bundle bifurcation in 1 patient. However, histologic investigation disclosed fibrosis and disruption of the proximal nonbifurcating His bundle in the patient who died suddenly. In 2 patients with recurrent supraventricular tachycardia, electrophysiologic studies suggested reentry through James fibers (or dual AV nodal pathway) in 1 and the presence of a left lateral accessory AV pathway in the other. Holter monitoring showed a high incidence of ventricular arrhythmias.