Pitfalls in diagnosis of atypical atrioventricular nodal reentrant tachycardia by a conventional electrophysiological study.

BACKGROUND

During atypical atrioventricular nodal reentrant tachycardia (AVNRT), the earliest atrial activation site following retrograde slow pathway (SP) conduction is at the atrial exit of the left inferior extension (LIE) in the coronary sinus (CS) or the right inferior extension (RIE) on the tricuspid annulus (TA).

OBJECTIVE

The purpose of this study was to assess the validity of a conventional 2-catheter (His bundle and CS) mapping method for localizing the atrial ends of these extensions.

METHODS

We retrospectively evaluated the efficiency of electrode placement-based mapping of the LIE and RIE in atypical AVNRT using electroanatomic 3-dimensional (3D) mapping validation.

RESULTS

Among 19 atypical AVNRTs (15 fast/slow, 4 slow/slow) in 14 patients (9 female; age 59 ± 17 years), 8 AVNRTs had LIE involvement and 11 had RIE. The 8 LIE exits were inside the CS, and localization by 3D mapping and CS electrode catheter matched in all. RIE exits were on the posterior TA where electrode catheters are conventionally not placed, requiring 3D mapping for accurate localization. During retrograde RIE conduction, CS ostium activated earlier than His-bundle electrogram (HBE) in 7 RIEs, HBE was earlier in 1, and they were simultaneous in 3, resulting in the presence of RIE being missed in 4 of 11 AVNRTs (36%) using current diagnostic criteria. The CS ostium and His-bundle activation times were determined by their relative closeness to the RIE exit.

CONCLUSION

Conventionally placed electrode catheter mapping in atypical AVNRT was able to identify 100% of LIEs but only 64% of RIEs. It is critical to place a catheter on the TA.