New DEStiny Revealed

Patient presentation: A 28-year-old woman with a long-standing history of palpitations presented to the emergency department for syncope. Three years prior she had unsuccessful radio frequency (RF) ablation for Wolf-Parkinson-White syndrome complicated by complete heart block necessitating dual-chamber pacemaker implantation. Following pacemaker implantation, she had partial recovery of atrioventricular conduction. A treadmill stress electrocardiogram after pacemaker implant revealed sinus rhythm at baseline with pre-excitation in a pattern of a mid-septal accessory pathway (AP). Her rhythm during recovery after stress was from the sinus node at 114 bpm with a prolonged PR interval (Length) and a right bundle branch block morphology without pre-excitation. A repeat electrophysiology procedure shortly thereafter revealed ventricular pre-excitation at baseline with no inducible arrhythmias with aggressive pacing maneuvers and isoproterenol infusion. There was no change in the degree of pre-excitation despite decremental AV node conduction, and there was a preserved HV interval during incremental RA pacing and preserved ventricular pre-excitation during junctional rhythm. These observations suggested a fasiculo-ventricular accessory pathway (FVAP), but a standard atrio-ventricular AP that had been partially ablated during her previous procedure could not be excluded. The His-Purkinje conduction was abnormal with a prolonged HV interval, right bundle branch block, and left anterior fascicular block. The AP mapped to a relatively wide area of the upper-mid RA septum and ablation was unsuccessful, despite extensive RF delivery to the right atrium septum. At that time, it was felt that the AP was most likely a fasiculo-ventricular pathway and did not participate in tachycardia. Her pacemaker was reprogrammed to VDD with long AV delay to minimize pacing. For the next three years, she remained asymptomatic until her episode of syncope. Dr. Knight: A FVAP is a common cause of ventricular preexcitation and can be an incidental observation. It is a connection from the His-bundle region to the local ventricular myocardium below the AV node, but does not result in AV reentrant tachycardia. Although AV block can occur as a complication of ablation attempts in a patient with an FVAP, the marked conduction disease would not be expected in most patients with WPW.