Acute and chronic effects of amiodarone on ventricular refractoriness, intraventricular conduction and ventricular tachycardia induction

In eight patients, the right ventricular effective refractory period, rate-dependent changes in intraventricular conduction (as reflected by QRS duration during ventricular paced cycle lengths of 600 to 250 ms) and results of programmed ventricular stimulation were determined in the control state, 5 minutes after the intravenous infusion of 10 mg/kg body weight of amiodarone and after 2 months of treatment with oral amiodarone. The right ventricular effective refractory period was 230 +/- 30 ms (mean +/- SD) in the control study, 248 +/- 27 ms after intravenous amiodarone (p less than 0.001) and 296 +/- 26 ms after oral amiodarone (p less than 0.001). In the control state, QRS duration was constant at all paced cycle lengths. Intravenous amiodarone resulted in a rate-dependent prolongation of QRS duration. This rate-dependent prolongation was markedly accentuated by oral amiodarone in six patients who had an elevated serum level of reverse triiodothyronine (T3) after 2 months of oral treatment, but it was not more pronounced than the effects of intravenous amiodarone in two patients with a normal reverse T3 serum level after oral therapy. Both intravenous and oral amiodarone either suppressed or modified the induction of ventricular tachycardia by programmed stimulation in some patients, but in a discordant fashion. The relative effects of intravenous and oral amiodarone on ventricular refractoriness and conduction and on ventricular tachycardia induction did not correlate with serum amiodarone levels. Chronic amiodarone therapy results in a marked prolongation in ventricular refractoriness compared with the relatively small but significant increase that occurs after intravenous amiodarone.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				S. Moro, M. Ferreiro, D. Celestino, E. Medei, M. V. Elizari, and S. Sicouri In Vitro Effects of Acute Amiodarone and Dronedarone on Epicardial, Endocardial, and M Cells of the Canine Ventricle Journal of Cardiovascular Pharmacology and Therapeutics, December 1, 2007; 12(4): 314 - 321. [Abstract] [PDF]

				P. Kulakowski, S. Karczmarewicz, G. Karpinski, M. Soszynska, and L. CeremuzYnski Effects of intravenous amiodarone on ventricular refractoriness, intraventricular conduction, and ventricular tachycardia induction Europace, January 1, 2000; 2(3): 207 - 215. [Abstract] [PDF]

				J. Merot, F. Charpentier, J.-M. Poirier, G. Coutris, and J. Weissenburger Effects of chronic treatment by amiodarone on transmural heterogeneity of canine ventricular repolarization in vivo: interactions with acute sotalol Cardiovasc Res, November 1, 1999; 44(2): 303 - 314. [Abstract] [Full Text] [PDF]

				Y. Kreiss, Y. Sidi, and H. Gur Efficacy and safety of intravenous amiodarone in recent-onset atrial fibrillation: experience in patients admitted to a general internal medicine department Postgrad. Med. J., May 1, 1999; 75(883): 278 - 281. [Abstract] [Full Text]

				C.-T. Tai, S.-A. Chen, A.-N. Feng, W.-C. Yu, Y.-J. Chen, and M.-S. Chang Electropharmacologic Effects of Class I and Class III Antiarrhythmia Drugs on Typical Atrial Flutter : Insights Into the Mechanism of Termination Circulation, May 19, 1998; 97(19): 1935 - 1945. [Abstract] [Full Text] [PDF]

				I. Kodama, K. Kamiya, and J. Toyama Cellular electropharmacology of amiodarone Cardiovasc Res, July 1, 1997; 35(1): 13 - 29. [Full Text] [PDF]

				J. N. Nanas and J. W. Mason Pharmacokinetics and Regional Electrophysiological Effects of Intracoronary Amiodarone Administration Circulation, January 15, 1995; 91(2): 451 - 461. [Abstract] [Full Text]

				X.-J. Du, M. D. Esler, and A. M. Dart Sympatholytic Action of Intravenous Amiodarone in the Rat Heart Circulation, January 15, 1995; 91(2): 462 - 470. [Abstract] [Full Text]