Induction of atrioventricular nodal reentrant tachycardia after atropine. Report of five cases.

After intravenous administration of 0.5 mg of atropine sustained atrioventricular (A-V) nodal reentrant tachycardia could be produced in five patients who had no prior historical or electrocardiographic evidence of supraventricular tachycardia. During the control period single atrial echo beats could be demonstrated in four of the five patients, but no instance of sustained tachycardia occurred. Atropine, known to enhance A-V nodal conduction, allowed achievement of longer A-H intervals (Case 1) and provided the necessary balance of conduction and refractoriness within the A-V nodal reentrant pathways (Cases 1 to 5) to sustain A-V nodal reentry in these patients.