Fasciculoventricular Pathway Mimicking Wolff-Parkinson-White Syndrome: A Delta Wave That Should Not Be Ablated

Fasciculoventricular pathways (FVPs) are rare and benign variants of ventricular preexcitation that may closely mimic septal atrioventricular accessory pathways on surface electrocardiography.

A woman in her 40s was referred for suspected Wolff-Parkinson-White syndrome with palpitations. The electrocardiogram demonstrated a short PR interval with subtle preexcitation. Electrophysiological study revealed a fixed His-ventricular interval of 28 milliseconds across sinus rhythm, atrial incremental, and extrastimulus pacing and junctional rhythm. Atrial extrastimulus pacing resulted in disappearance of preexcitation with transition to complete right bundle branch block morphology, reflecting functional right bundle branch refractoriness. These findings were diagnostic of an FVP.

A fixed His-ventricular interval across multiple pacing maneuvers represents the key electrophysiological feature distinguishing FVPs from true septal accessory pathways.

Accurate recognition of FVPs is essential to avoid misdiagnosis and unnecessary ablation near the His-Purkinje system.