Abstract
Background
Twin atrio ventricular (AV) nodal tachycardia is a rare mechanism of supra ventricular arrhythmia, only seen in some specific congenital heart defects (CHD). It consists of a reentrant circuit between two distinct AV nodes (anterior and inferior). Since both nodes have antegrade and retrograde conduction, there is usually two QRS morphologies in sinus rhythm.
Case summary
This case is about an atypical twin AV nodal tachycardia in a 15 years-old patient with congenitally corrected transposition of the great arteries (cc-TGA) and previous history of a ventricular septal defect (VSD) repair. The surgical closure was probably responsible of a poor antegrade conduction over the inferior AV node, that was responsible for a unique QRS morphology. He finally received a catheter ablation of the inferior AV node. He remained asymptomatic without anti-arrhythmic drugs at 8-months post-ablation.
Discussion
Twin atrioventricular nodal re-entrant tachycardia is a rare phenomenon. The presentation and electrophysiological study can be both atypical due to previous surgical repair. Operator should be aware of specific CHD where twin atrioventricular nodal re-entrant tachycardias are expected.
Surgical Repair of Ventricular Septal Defect Associated with Congenitally Corrected Transposition of the Great Arteries.
