Presence and significance of the left atrionodal connection during atrioventricular nodal reentrant tachycardia

It has been suggested that the anatomic substrates of dual atrioventricular nodal pathways are likely to be the atrionodal connections. During atriove ntricular nodal reentrant tachycardia (AVNRT) or ventricular pacing (VP), a n earliest retrograde atrial activation in the coronary sinus (CS) distal t o the ostium (CS breakthrough) would suggest the presence of an exit from a left atrionodal connection. The aim of the study was to evaluate the incid ence of such an atrial retrograde activation in the CS during AVNRT and VP. The retrograde atrial activation was recorded during typical AVNRT (38 pat ients, 27 women, mean age 44 +/- 18 years) by a multipolar catheter in the CS, a decapolar catheter in the His bundle position, and a deflectable quad ripolar catheter along the tricuspid annulus anterior to the CS ostium. In 31 patients the retrograde atrial activation was recorded also during VP at a similar cycle length. A CS breakthrough was found in 18 patients during AVNRT (47%) and in 13 patients during VP (42%). Presence or absence of CS b reakthrough was concordant between AVNRT and VP in 90% of the patients. A C S breakthrough, suggesting a left-sided atrionodal connection, is frequentl y recorded both during AVNRT and VP. In patients with a CS breakthrough pat tern, the absence of correlation between the His bundle to the earliest CS retrograde atrial electrogram interval and AVNRT cycle length, or any other atrial activation times recorded in the posterior and anterior region of t he Koch's triangle, would suggest that the left-sided atrionodal connection is a bystander during typical AVNRT. (C) 1999 by Excerpta Medica, Inc.