Adenosine in treating cardiac arrhythmias.

1. Adenosine is an endogenous nucleoside which causes a brief blockade of the AV nodal conduction pathway following intravenous administration. 2. Such a brief AV block can be used therapeutically for reliable termination of AV nodal re-entry tachycardia and WPW re-entry tachycardia. It can also be used for demasking atrial activity in rapid suspected supraventricular tachycardia with a broad QRS complex or a Delta wave, not present during sinus rhythm with normal AV node conduction, indicating the presence of a hidden WPW syndrome. 3. Side effects after adenosine application are frequent, but very transient rarely serious (1-3% of cases, e.g. status asthmaticus, ventricular fibrillation) and therefore require a certain degree of experience with this drug on the part of the treating physician.