Variants of accessory pathways

Abstract

Variant accessory pathways include atriofascicular, nodofascicular, nodoventricular, atrio-Hisian, and fasciculoventricular pathways. Atriofascicular pathways are the most common with others occurring rarely. The anatomical descriptions, electrocardiographic findings, electrophysiologic findings, and clincial manifestations are discussed. K E Y W O R D Saccessory pathways, atriofascicular, atrio-Hisian, Brechenmacher, catheter ablation, fasciculoventricular, Mahaim, nodofascicular, nodoventricular

Fasciculoventricular bypass tracts: Electrocardiographic and electrophysiologic features

“…FV APs are extremely rare preexcitation variants which have distinctive ECG and electrophysiological features. These fibers take off from the His bundle and the fascicles to the right ventricle 1,2 . They have only antegrade and nondecremental conducting properties 1,2 .…”

“…These fibers take off from the His bundle and the fascicles to the right ventricle 1,2 . They have only antegrade and nondecremental conducting properties 1,2 . The ECG is characterized by normal frontal plane axis, similar to an anteroseptal APs, a subtle preexcitation, and a normal PR interval.…”

“…Regarding the electrophysiologic features of FV APs, the HV interval (H‐delta) is always short (10‐35 ms) 1,2 . During incremental atrial pacing, the progressive increase of AH interval along with a fixed HV interval and the same degree of preexcitation are suggestive of FVP 1,2 . On the contrary, a NF or NV is not totally an infranodal structure, as it bypasses only a part of the AV node which displays decremental conduction properties.…”

“…Block at the FV AP during incremental atrial pacing results in normal HV interval, and produces a narrow QRS complex without preexcitation. The presence of FV APs is further suggested when the administration of adenosine prolongs the PR interval or the AH interval without changing the degree of preexcitation 1,2 . The presence of preexcited junctional beats favors the diagnosis of FV APs 1,2 .…”

“…Fasciculoventricular (FV) accessory pathways (AP) are uncommon preexcitation variants 1,2 . The differential diagnosis of FV APs from anteroseptal atrioventricular APs and nodoventricular (NV)/nodofascilular (NF) APs can be challenging 1,2 . Based on two cases, we discuss the specific electrocardiographic and electrophysiologic features of FV bypass tracts.…”