A case of preexcitation syndrome showing atypical atrioventricular nodal reentrant tachycardia and orthodromic atrioventricular reciprocating tachycardia with a bystander concealed nodoventricular/nodofascicular pathway

Unusual response to His‐synchronous ventricular stimulation during a supraventricular tachycardia: Atrial advancement with or without resetting?

“…Such a finding excludes both AT and pure AVNRT; on the other hand, this finding does not rule out an AVNRT with atypical AP and limits the differential diagnosis to orthodromic tachycardia (ORT) using a decremental atrioventricular AP (also called the permanent form of junctional reciprocating tachycardia), ORT using a nodofascicular/nodoventricular (NF/NV) pathway, and atypical AVNRT with a concealed, bystander NF/NV pathway 17 . When concealed NV/NF pathway connecting to slow pathway is present, 23 Hr‐VES for atypical AVNRT is associated with reset of the tachycardia with delay and/or termination of the tachycardia without atrial capture 24 . The reason is that even in the case of AV dissociation, which typically happens when a VES is not conducted back to the atria, AVNRT can still go on, as the reentrant circuit is defined in the AV node and His–Purkinje system is not a part of it.…”

“…17 When NV/NF pathway connecting to slow pathway is present, 23 Hr-VES for atypical AVNRT is associated with reset of the tachycardia with delay and/or termination of the tachycardia without atrial capture. 24 The reason is that even in the case of AV dissociation, which typically happens when a VES is not conducted back to the atria, AVNRT can still go on, as the reentrant circuit is defined in the AV node and His-Purkinje system is not a part of it. F I G U R E 1 A VES (A) preexciting the subsequent atrial deflection and (B) termination response when the His is refractory.…”