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[Complete atrioventricular block and sudden death in isolated corrected transposition]
Insights
Corrected transposition of the great arteries (cTGA) carries a high risk of atrioventricular (AV) conduction disturbances. This case highlights sclero-atrophy of the AV bundle as a cause of complete AV block and ventricular arrhythmias in isolated cTGA.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
- Congenital Heart Disease
Background:
- Corrected transposition of the great arteries (cTGA) is a complex congenital heart defect.
- Patients with cTGA have an increased risk of atrioventricular (AV) conduction disturbances.
- The anatomical malposition of the specialized AV junction in cTGA may predispose to conduction abnormalities.
Observation:
- A 54-year-old female with a history of "idiopathic" complete AV block experienced sudden cardiac death.
- Autopsy revealed isolated cTGA without other cardiac anomalies.
- Electrocardiogram (ECG) showed ventricular fibrillation preceded by ventricular tachycardia.
Findings:
- Histological examination of the conduction system demonstrated an anteriorly positioned AV node.
- The bundle of His had a prolonged subendocardial course within the pulmonary outflow tract.
- The pathological basis for the complete AV block was identified as sclero-atrophy of the common AV bundle, similar to acquired AV block.
Implications:
- This case underscores the significant risk of conduction system disease in isolated cTGA.
- The findings suggest a potential link between AV block and the development of life-threatening ventricular arrhythmias in cTGA.
- Understanding these mechanisms is crucial for risk stratification and management of patients with cTGA.
Abstract:
The rate of av conduction disturbances in corrected transposition of the great arteries is high, possibly as consequence of mechanical injury by ventricular output along with the mis-positioned specialized av junction. A sudden death occurred in a 54 year old female affected by a chronic "idiopathic" complete av block, who showed at autopsy a heart with av and ventricular arterial discordance in the absence of other anomalies (isolated corrected transposition). The cardiac arrest had the ecg features of ventricular fibrillation, preceded by sustained ventricular tachycardia. Histologic study of the conduction system by serial sections confirmed the anterior position of the connected av node, with a long subendocardial course of the bundle in the pulmonary outflow tract. The histologic basis of the block consisted of sclero-atrophy of the common bundle, quite similar to the substrate of acquired av block in heart with normal connections. Possible etiologies, responsible of the relation between the av block and onset of ventricular arrhythmias, are discussed.