Ventriculatrial Block During Atrioventricular Nodal Reentrant Tachycardia Suggesting Existence of an Upper Common Pathway

Abstract

SUMMARYStudies on the mechanisms of atrioventricular nodal reentrant tachycardia (AVNRT) have yet to clarify whether the slow and fast pathways connect directly with the atria or via an upper common pathway. Although a "final common pathway" connecting the slow and fast pathways to the proximal His bundle was thought to be part of the reentrant circuit, debate on the presence of an upper common pathway continues. We report a case of AVNRT continuing despite the occurrence of ventriculoatrial block, thus supporting the existence of an upper common pathway. (Int Heart J 2005; 46: 333-338)

Characteristics of Slow Pathway Conduction After Successful AVNRT Ablation

“…It may be eliminated, revealing the presence of another SP incapable of participating in tachycardia. The SP may remain unchanged, but interaction with the FP may be disrupted in a manner that prevents further tachycardia 20–23 . Lastly, the anatomic circuit may be unchanged but initiating beats reduced or their access to the reentrant circuit impaired, decreasing the likelihood of spontaneously occurring tachycardia.…”

Broad complex tachycardia in a patient with a pacemaker: What is the mechanism?

“…The differential diagnoses in this circumstance include the following: 2 VT, with: Ventriculoatrial (VA) block 1:1 VA conduction and true or functional atrial undersensing Rarer possibilities, such as atrial (or upper common pathway) block in association with: AV nodal reentrant tachycardia Junctional tachycardia Intra-hisian reentrant tachycardia 3 , 4 Reentrant tachycardia utilizing a concealed nodoventricular or nodofascicular pathway Atrial tachycardia or flutter with atrial undersensing. …”