Blood levels and electrophysiological effects of intravenous amiodarone in patients with junctional reciprocating tachycardia. Preliminary observations.

The time course and the mode of antiarrhythmic action of Amiodarone was studied after acute i.v. injection of the drug (5 mg/kg in 5 min) to four patients with junctional reciprocating tachycardia. Electrophysiological studies were performed before and 1 and 2 hours after Amiodarone injection. It was impossible or considerably more difficult to induce junctional reciprocating tachycardia after Amiodarone, and the drug's effect was detectable mainly on the AV node. Kinetic analysis of blood levels of Amiodarone during the electrophysiological study did not support a direct association between blood concentration and its effects.