The various manifestations of concealed nodofascicular/nodoventricular bypass tracts

Background: The various arrhythmic manifestations of concealed nodofascicular (NF)/nodoventricular (NV) bypass tracts (BPTs) are poorly understood.

Objective: The purpose of the study was to define diagnostic criteria for supraventricular tachycardias (SVTs) associated with concealed nodal pathways (NPs).

Methods: We reviewed 11 patients with concealed NPs who underwent electrophysiology study and ablation for symptomatic SVT.

Results: Of 11 patients 7 (64% women; mean age 54 ± 16 years), NF/NV BPTs were active bystanders during atrioventricular nodal reentrant tachycardia (atypical [n = 4]; typical [n =2]) or participants during orthodromic NF/NV reentrant tachycardia (n = 5). The majority (10 of 11 [91%]) had nodal origin in the slow pathway (SP) and 7 of 11 (64%) presented as long RP SVT. Ablation of the SP targeting the right (n = 10) or left (n = 1) inferior extension eliminated concealed NP-associated SVTs in all patients.

Conclusion: Concealed NF/NV BPTs are active bystanders equally as common as participants during SVT. They typically insert into the SP and often present as long RP SVT. SP ablation eliminates concealed NF/NV BPT-associated SVTs regardless of the mechanism.