Abstract
Introduction: The surface EKG of typical atrioventricular nodal
reentrant tachycardia (AVNRT) shows simultaneous ventricular-atrial (RP)
activation with pseudo R’ in V1 and typical heart rates ranging from
150-220/min. Slower rates are suspicious for junctional tachycardia
(JT). However, occasionally we encounter typical AVNRT with slow
ventricular rates. We describe a series of typical AVNRT cases with
heart rates under 110/min.
Methods: A total of 1972 patients with AVNRT who underwent slow
pathway ablation were analyzed. Typical AVNRT was diagnosed when; 1)
evidence of dual atrioventricular nodal conduction, 2) tachycardia
initiation by atrial drive train with A-H-A response, 3) septal
ventriculoatrial (VA) time < 70 ms, and 4)
ventricular-atrial-ventricular (V-A-V) response to ventricular overdrive
(VOD) pacing with post pacing interval-tachycardia cycle length
(PPI-TCL) > 115ms. JT was excluded by either termination or
advancement of tachycardia by atrial extrastimuli (AES) or atrial
overdrive (AOD) pacing.
Results: We found 11 patients (Age 20-78 years old, 6 female)
who met the above-mentioned criteria. The TCL ranged from 560ms to
782ms. Except for one patient showing tachycardia termination, all
patients demonstrated a V-A-V response and PPI-TCL over 115ms with VOD.
AES or AOD pacing successfully excluded JT by either advancing the
tachycardia in 10 patients or by tachycardia termination in one patient.
Slow pathway was successfully ablated, and tachycardia was not inducible
in all patients.
Conclusions: This case series describes patients with typical
AVNRT with slow ventricular rate (less than 110/min) who may mimic JT.
We emphasize the importance of using pacing maneuvers to exclude JT.
Keywords : Typical AVNRT, Junctional tachycardia, Slow
ventricular rate