Adenosine-induced complete heart block: not so transient.

Adenosine is a purine nucleoside widely used to terminate supraventricular tachycardias, and as a diagnostic adjunct in narrow complex regular tachycardia of uncertain origin. Atrioventricular blockade and bradyarrhythmias following administration are common but generally short-lived. We report a case of prolonged complete heart block requiring intubation and temporary pacing, following adenosine administration in atrial flutter treated with combination metoprolol and diltiazem.