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Wide QRS-complex tachycardia with variable VA-conduction: what is the mechanism?
Hildegard Tanner1, Takao Sakata, Etienne Delacrétaz
1Swiss Cardiovascular Center Bern, University Hospital, CH-3010 Bern, Switzerland.
This study details a case of recurrent wide-QRS-complex tachycardia in a patient with corrected tetralogy of Fallot, identifying atrioventricular node re-entrant tachycardia as the cause. Radiofrequency ablation successfully treated the condition, highlighting variable VA conduction in such cases.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Case Reports
Background:
- Tetralogy of Fallot (TOF) repair can predispose patients to cardiac arrhythmias.
- Recurrent wide-QRS-complex tachycardia presents a diagnostic challenge, especially in post-surgical congenital heart disease patients.
Observation:
- A 16-year-old female with surgically corrected TOF experienced recurrent wide-QRS-complex tachycardia.
- Tachycardia was inducible and terminable solely by ventricular pacing, with identical QRS morphology during sinus rhythm and tachycardia.
- Variable ventriculoatrial (VA) conduction was noted, initially suggesting a bundle branch re-entrant mechanism.
Findings:
- Detailed electrophysiological mapping revealed cranial to caudal His bundle depolarization.
- This pattern led to the diagnosis of atrioventricular node re-entrant tachycardia (AVNRT).
- Radiofrequency catheter ablation targeting the slow AV nodal pathway effectively abolished the tachycardia.
Implications:
- This case demonstrates that variable VA conduction can occur in AVNRT.
- It suggests that atrial tissue may not always be essential for the re-entrant circuit in AVNRT.
- Accurate diagnosis and targeted ablation are crucial for managing complex tachycardias in TOF patients.
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