Longitudinal dissociation of atrioventricular accessory pathways

Abstract

Unusual properties of atrioventricular (AV) accessory pathways were found during electrophysiologic investigations in four patients (three men and one woman). Anterograde longitudinal dissociation of the accessory pathway was observed in two patients and retrograde longitudinal dissociation in two others. Two patients had an accessory pathway with a slow conduction time, one in anterograde direction and one in retrograde direction. These observations further expand our knowledge of the spectrum of electrophysiologic properties of accessory AV pathways.

Duality of Conduction in an Atriofascicular Pathway During Antidromic Tachycardia

“…Cycle‐length‐alternans in antidromic tachycardia through an atriofascicular pathway because of changes in AV interval without a significant change in QRS complexes and VA interval has rarely been reported 1,2 . Functional duality of conduction over this pathway due to the longitudinal dissociation into two with different conduction velocities and refractoriness could explain this rare phenomenon 1–5 . However, a single Mahaim fiber distally diverging anatomically into two with different electrophysiologic properties cannot be excluded based only on these observations.…”

Narrow QRS complex tachycardia: What is the mechanism?

“…Therefore, the changes in cycle length could not be explained by “Wenkebach-type” behavior. It is possible that a damaged slow pathway with longitudinal dissociation 3 or two anatomically close slow pathways could explain the oscillation. During ventricular overdrive pacing, figure 2A, tachycardia continued with the same atrial activation despite full ventricular capture and then terminates without advancing the atrium.…”

Wide Complex Tachycardia with RR and QRS Alternans: What Is the Mechanism?

“…However, the induction of the tachycardia by atrial ectopics strongly supports SVT with aberration or preexcited tachycardia. The cycle length alternans during the tachycardia can occur in ventricular tachycardia or supraventricular tachycardia 1–3 . During the cycle length variation, changes in ventricular to ventricular interval (VV) determined changes in atrial to atrial interval (AA) and not vice versa.…”