Key result
Electrophysiology studies and ablation in 8 patients demonstrated that manifest nodoventricular fibers can cause wide-complex tachycardia, with successful ablation initially targeting the slow pathway.
Why the study?
Manifest nodofascicular and nodoventricular pathways are rare, and this report aimed to highlight their electrophysiological properties and ablation sites.
What are the electrophysiological properties and optimal ablation sites for manifest nodoventricular/nodofascicular fibers?
Case Report (n=8)
What are the electrophysiological properties and optimal ablation sites for manifest nodoventricular/nodofascicular fibers?
Manifest nodoventricular/nodofascicular fibers have variable presentations, and ablation should initially target the slow pathway region, with mapping of the right ventricle insertion site if unsuccessful.
BACKGROUND: Nodofascicular and nodoventricular (NFV) accessory pathways connect the atrioventricular node and the Purkinje system or ventricular myocardium, respectively. Concealed NFV pathways participate as the retrograde limb of supraventricular tachycardia (SVT). Manifest NFV pathways can comprise the anterograde limb of wide-complex SVT but are quite rare. The purpose of this report is to highlight the electrophysiological properties and sites of ablation for manifest NFV pathways. METHODS: Eight patients underwent electrophysiology studies for wide-complex tachycardia (3), for narrow-complex tachycardia (1), and preexcitation (4). RESULTS: NFV was an integral part of the SVT circuit in 3 patients. Cases 1 to 2 were wide-complex tachycardia because of manifest NFV SVT. Case 3 was a bidirectional NFV that conducted retrograde during concealed NFV SVT and anterograde causing preexcitation during atrial pacing. NFV was a bystander during atrioventricular node re-entrant tachycardia, atrial fibrillation, atrial flutter, and orthodromic atrioventricular re-entrant tachycardia in 4 cases and caused only preexcitation in 1. Successful NFV ablation was achieved empirically in the slow pathway region in 1 case. In 5 cases, the ventricular insertion was mapped to the slow pathway region (2 cases) or septal right ventricle (3 cases). The NFV was not mapped in cases 5 and 7 because of its bystander role. QRS morphology of preexcitation predicted the right ventricle insertion sites in 4 of the 5 cases in which it was mapped. During follow-up, 1 patient noted recurrent palpitations but no documented SVT. CONCLUSIONS: Manifest NFV may be critical for wide-complex tachycardia/manifest NFV SVT, act as the retrograde limb for narrow-complex tachycardia/concealed NFV SVT, or cause bystander preexcitation. Ablation should initially target the slow pathway region, with mapping of the right ventricle insertion site if slow pathway ablation is not successful. The QRS morphology of maximal preexcitation may be helpful in predicting successful right ventricle ablation site.
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Nazer et al. (2019) conducted a case report in Manifest nodoventricular/nodofascicular fibers with tachycardia or preexcitation (n=8). Electrophysiology study and ablation was evaluated on Electrophysiological properties and sites of ablation. Electrophysiology studies and ablation in 8 patients demonstrated that manifest nodoventricular fibers can cause wide-complex tachycardia, with successful ablation initially targeting the slow pathway.
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