Abstract: Aim To assess the value of the administration of adenosine-5'-triphosphate (A TP) during sinus rhythm for noninvasive diagnosis of AV node dual pathways(AVNDP) and aboli tion or modification of the slow pathway (SP) after radiof requency (RFCA) in patient s with inducible sustained AVNRT.Methods Incremental doses of ATP were int ravenously administ rated during sinus rhy thm to patients with spontaneous or inducible sustained AVN RT (study group, n=45) and to patients with no evidence of AVNDP or inducible AVNRT (control group, n= 37) until ECG sig ns of AVNDP (50 ms increase or decrease in P-R interval in two consecutive beats, or occurrence of AVNRT) or second-degree AV block were observed.Results Four patients (two in study patient s and two in co nt rol patients) could not complete the t rial and were excluded from analysis. AVNDP was observed by ATP in 36(84%) study patients, whereas it was diagnosed by electrophy siology criteria in 38(88%) patients.AVNDP was observed only in 1(3%) control patient.AVNDP by ATP test was disappeared in 18(90%) of 20 patients who underwent SP abolition and in 3 (38%) of 8 patients who underwent SP modification.Conclusion ATP test during sinus rhythm enables noninvasive diagnosis of AVNDP in a high percentage of patients with inducible AVN RT and reliably confirms the Results of RFCA of the SP.

Key words: adenosinet riphosphate, tachycardia, atrioventricular nodal dual pathway, elect rophgsiology