NONINVASIVE DIAGNOSIS OF DUAL AV NODE PHYSIOLOGY IN PATIENTS WITH AV NODAL REENTRANT TACHYCARDIA BY ADMINISTRATION OF ADENOSINE-5'-TRIPHOSPHATE DURING SINUS RHYTHM

Background-Atrioventricular nodal reentry tachycardia (AVNRT) represen ts the most commonly encountered type of regular paroxysmal supraventr icular tachycardia. This study determined whether administration of ad enosine-5'-triphosphate (ATP) during sinus rhythm may be useful in the noninvasive diagnosis of dual AV nodal pathways. Methods and Results- During electrophysiological study, we intravenously administered incre mental doses of ATP (from 10 to 50 mg) during sinus rhythm to patients with spontaneous and inducible sustained AVNRT (study group, n=42) an d to patients with no evidence of dual AV nodal physiology or inducibl e AVNRT (control group, n=21). Signs suggestive of dual AV node physio logy after ATP administration during sinus rhythm (''jump'' of AH grea ter than or equal to 50 ms between 2 consecutive beats, greater than o r equal to 1 AV nodal echo beat, or initiation of AVNRT) were observed in 32 (76%) of 42 study patients but in only 1 (5%) of the 21 control patients (P<0.001), Similar results were observed when only surface l ead recordings (without intracardiac recordings) were evaluated. Signs suggestive of dual AV node physiology by the ATP test were observed i n 29 (80.5%) of 36 patients who had electrophysiological demonstration of dual AV node physiology and in 3 (50%) of 6 patients without AV no dal duality (P=NS). Signs suggestive of dual physiology according to t he ATP test disappeared in 11 (92%) of the 12 patients who underwent s uccessful slow AV nodal ablation but persisted in 8 (62%) of 13 patien ts who underwent AV nodal modification. Conclusions-Administration of ATP during sinus rhythm may be a useful bedside test for identifying p atients with dual AV nodal pathways who are prone to AVNRT. This simpl e test should be considered as a screening test for patients with symp toms suggestive of paroxysmal supraventricular tachycardia but no docu mented arrhythmias or for patients with documented narrow complex tach ycardia of unclear mechanism.