[Electrophysiologic effects of orally administered amiodarone]

The authors made an invasive electrophysiological examination of the heart before and after administration of amiodarone by the oral route in 18 patients (15 men and 3 women). Amiodarone was administered in maintenance doses of 200 or 400 mg/day for 3 to 13 months (mean 4.7 months). Comparison of values revealed a significant protraction of R-R, P-Q and QRS intervals on the surface ECG. A-H and H-V intervals on the electrogram of the bundle of His as well as effective refractory periods of the ventricular myocardium were significantly protracted. During high-frequency stimulation of the atria the frequency at which an a-v block grade II type I develops declined. No significant changes developed in Q-Tc intervals on the surface ECG, the PA-A on the electrogram of the bundle of His and in the corrected recovery period of the s-a node.