Adenosine in the noninvasive diagnosis of dual AV nodal conduction: use asa follow-up parameter after slow pathway ablation in AVNRT

Objective - The aim of this study was to evaluate if administration of aden osine during sinus rhythm to patients with PSVT of unknown mechanism is cap able to detect dual AV nodal conduction and furthermore to evaluate this di agnostic parameter as a controlling test after slow pathway ablation in AVN RT. Methods and results - Before electrophysiological study 35 consecutive pati ents with PSVT were given adenosine during sinus rhythm. After radiofrequen cy ablation the adenosine test was repeated in a subset of 19 patients,The electrophysiological study revealed 19 patients (54%) with typical AVNRT (s tudy group), 10 (29%) with atrioventricular reentry tachycardia (AVRT), 4 ( 11%) with ectopic atrial tachycardia (EAT) and 2 patients (6%) with inducib le atrial flutter (AF) (control group). We observed a sudden increment of t he PQ interval of more than 50 msec between two consecutive beats in 15 of 19 patients (79%) in the study group (75 +/- 35 msec) and in 2 patients (I with EAT, AF) of the control group (19 +/- 12 msec) (p <0.001). After slow pathway radiofrequency ablation the sudden increment of PQ interval persist ed in 4 of 12 patients (33%) of the study group. Three of these 4 patients had a relapse of AVNRT during a follow-up of 3 months. Conclusion - The administration of adenosine during sinus rhythm is an exce llent noninvasive diagnostic test for identifying dual AV nodal conduction and additionally for verifying radiofrequency ablation results in patients with AVNRT.