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.