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.
A Case of Slow-fast Atrioventricular Nodal Reentrant Tachycardia Needed to Distinguish from Junctional Tachycardia due to Conflicting Responses to Premature Atrial Contractions After Slow Pathway Ablation
