[Analysis of the electrophysiological effects of amiodarone using simultaneous recordings of monophasic and bundle-of-his action potentials].

The effects of amiodarone given by rapid intravenous injection at a dosage of 10 mg/kg have been studied in the dog. The peak activity is found between the fifth and the tenth minute. The rate of discharge of the sinus is lowered by 36%. At the atrial level, the duration of the monophasic action potential (MAP) is increased by 9% and its dv/dt is lowered slightly, the total refractory period is increased by 22%, the effective refractory period is increased by 27%, the functional refractory period is increased by 19%, the ratio of the length of the effective period/duration of the MAP becomes slightly greater than unity, conduction facilitation disappears, and the period of slow conduction increases. In the A/V node the AH interval increases by 44% under normal rhythm, while atrial stimulation at 200/min. results in conversion to total AV block in more than half of the cases. The potential of the bundle of His and the HV interval are not altered. At ventricular level the duration of the monophasic action potential increases by 25%, its dv/dt decreases slightly, the total refractory period is increased by 8%, and the effective refractory period is increased by 14%.