Sequence of retrograde atrial activation in patients with dual atrioventricular nodal pathways.

Abstract

SUMMARY To characterize the sequence of retrograde atrial activation in the presence of dual atrioventricular (AV) nodal pathways, we analyzed electrophysiologic data from seven patients in whom discontinuous AV nodal and ventriculoatrial conduction curves could be induced with programmed electrical stimulation. In all patients, electrograms of the high right atrium (HRA), lateral right atrium (LRA), low septal right atrium (SRA) and proximal coronary sinus (PCS) near the coronary sinus ostium were simultaneously recorded at a paper speed of 150-250 mm/sec. During programmed ventricular extrastimulation and incremental ventricular pacing, ventriculoatrial conduction via the fast AV nodal pathway resulted in SRA activation before PCS, HRA and LRA activation. However, the sequence of retrograde atrial activation abruptly changed with a shift from retrograde fast to retrograde slow AV nodal pathway conduction. Characteristically, during ventriculoatrial conduction via the slow AV nodal pathway, activation of the PCS preceded SRA activation by 5-20 msec and was accompanied by an alteration of the temporal relationship between HRA and LRA activation in all patients. These observations suggest that anatomically, the proximal common AV nodal pathway is a broad area that permits the slow AV nodal pathway to have a retrograde exit located posteriorly, inferiorly and to the left of that of the fast AV nodal pathway, and that the retrograde atrial activation sequence recorded during tachyarrhythmias should be determined with caution while attempting to differentiate retrograde normal AV pathway from retrograde anomalous bypass tract conduction.IN DIFFERENTIATING retrograde conduction via the normal atrioventricular (AV) pathway from an anomalous bypass tract, one must evaluate ventriculoatrial conduction properties during an electrophysiologic study.'-" Ventriculoatrial conduction over the normal AV pathway is characterized by the earliest activation of the low septal right atrium (SRA) recorded in the His bundle electrographic lead and progressive prolongation of ventriculoatrial conduction time with increasing prematurity of ventricular extrastimulation. In contrast, ventriculoatrial conduction over an anomalous bypass tract has the earliest atrial activation at the site of its atrial insertion, and, characteristically, there is a lack of refractory-dependent ventriculoatrial conduction delay despite progressively premature ventricular extrastimulation.1 3 Dual AV nodal pathways are generally believed to be intranodal structures.4"8 Both fast and slow AV nodal pathways possess AV nodal properties with refractory-dependent conduction delay in both antegrade and retrograde directions.6-8 However, studies on the sequence of retrograde atrial activation have been limited to the fast AV nodal pathway.9' 10 In the present study, we characterize and compare retrograde atrial activation sequences that result from ventriculoatrial conduction via the fast and the slow AV nodal pathways. Materials and MethodsElectrophysiologic evid...

Demonstration of the Exact Anatomic Tachycardia Circuit in the Fast-Slow Form of Atrioventricular Nodal Reentrant Tachycardia

“…In addition, it has been shown that the destruction of the inferior extensions of the AV node underlies successful slow pathway ablation. 26 The findings of the present report, as well as previously reported results, 21,22 are consistent with the anatomic findings of Inoue et al 25 In the present study, it was also shown that the exit site of the slow pathway was separated by the intervening atrial tissue from the entrance of the fast pathway during tachycardia. These findings suggest the presence of a discrete anatomic structure for the slow pathway, as suggested by Inoue et al 25 Recently, heterogeneity of the fast and slow pathway conduction patterns in the FS-AVNRT was reported.…”

Patient with Atrioventricular Node Reentrant Tachycardia with Eccentric Retrograde Left-sided Activation. Treatment with Radiofrequency Catheter Ablation.

“…[1][2][3] The earliest retrograde atrial activation usually is recorded at the coronary sinus ostium because the slow pathway is located near the coronary sinus. 4) Compared with this type of retrograde atrial activation, the eccentric retrograde atrial activation suggested the presence of an accessory pathway. 12,13) However, it has been reported that multiple AV nodal pathways exist in some patients, and that some of them are located in the deeper layers of the atrial septum, and are connected to perinodal atrial tissues.…”

“…3) Because the slow pathway is located near the coronary sinus, 4) the earliest retrograde atrial activation in the atypical type of AVNRT is usually recorded at the coronary sinus ostium. 4) It has recently been reported that multiple AV nodal pathways exist in patients with the atypical type of AVNRT, and that some of the pathways are located in the deeper layers connected to perinodal atrial tissues. [5][6][7] Hwang, et al have reported that AVNRT with left-sided activation, which may occur with such a connection, is relatively rare.…”

Atrioventricular Nodal Re-Entrant Tachycardia with Two Functionally Discrete Fast Pathways

“…These phenomena do not support the possibility that a single atrioventricular nodal re-entrant circuit has two atrial exit sites (anterior and posterior exits). 12 Accordingly, we could hypothesize that the fast pathway through which the extra-stimuli penetrated is not associated with the essential re-entrant circuit; in other words, that it is involved with a bystander pathway, and another fast pathway may be operative as the retrograde limb of the essential re-entry circuit. As shown in Fig.…”