At the Atrioventricular Crossroads: Dual Pathway Electrophysiology in the Atrioventricular Node and its underlying Heterogeneities

Abstract

The atrioventricular node (AVN) is a complex structure that performs a variety of functions in the heart. The AVN is primarily an electrical gatekeeper between the atria and ventricles and introduces a delay between atrial and ventricular excitation, allowing for efficient ventricular filling. The AVN is composed of several compartments that safely transmit electrical excitation from the atria to the ventricles via the fast or slow pathways. There are many electrophysiological differences between these pathways, including conduction time and electrical refractoriness, that increase the predisposition of the atrioventricular junction to arrhythmias such as atrioventricular nodal re-entrant tachycardia. These varied electrophysiological characteristics of the fast and slow pathways stem from their unique structural and molecular composition (tissue and cellular geometry, ion channels and gap junctions). This review summarises the structural and molecular heterogeneities of the human AVN and how they result in electrophysiological variations and arrhythmias.

An integrated overview of AV node physiology

“…This does not mean that compact node conducts rapidly. As supported with dye mapping data, the FP may conduct more slowly than SP but would involve a shorter path …”

“…This preparation can be maintained in a stable functional state over time and minimizes “noise,” that is, variability as compared to in‐vivo conditions. More recently, the preparation has been used for immunohistochemical and mapping studies that have delineated the role of substructures in AV nodal activation . The preparation is usually electrically driven from a bipolar electrode positioned near the sinus node so that resulting atrial activation is analogous to that arising from a sinus impulse.…”

“…Ko et al confirmed that the PNE, lower nodal bundle, and His bundle form a continuum. George et al mapping data indicate that the slow‐fast reentrant circuit (main circuit used in AVNRT) likely involves transitional tissues, PNE, lower nodal bundle, and compact node.…”

“…Our goal is to present current knowledge on AV nodal function into a common simplified integrated model. Further information upon AV nodal function and its modulations by autonomic tone, drugs, and pathological processes can be found in several reviews and book …”

A Rare Evidence of a Dual Atrioventricular Nodal Physiology in a Patient with Narrow Complex Tachycardia

“…Various electrophysiological findings and maneuvers can prove the AVNRT to be a mechanism of tachycar dia during electrophysiology study (EPS). 1,2 The most commonly used definition of a dual AV nodal physio logy is the jump and echo phenomenon noted during an EPS. Jump is defined as an increase in the A-H interval of more than 50 ms, with a 10 ms decrement in an extrastimuli or a 10 ms decrement in an atrial drive train.…”