title: Acute amiodarone promotes drift and early termination of spiral wave re-entry.
abstract: Intravenous application of amiodarone is commonly used in the treatment of life-threatening arrhythmias, but the underlying mechanism is not fully understood. The purpose of the present study is to investigate the acute effects of amiodarone on spiral wave (SW) re-entry, the primary organization machinery of ventricular tachycardia/fibrillation (VT/VF), in comparison with lidocaine. A two-dimensional ventricular myocardial layer was obtained from 24 Langendorff-perfused rabbit hearts, and epicardial excitations were analyzed by high-resolution optical mapping. During basic stimulation, amiodarone (5 microM) caused prolongation of action potential duration (APD) by 5.6%-9.1%, whereas lidocaine (15 microM) caused APD shortening by 5.0%-6.4%. Amiodarone and lidocaine reduced conduction velocity similarly. Ventricular tachycardias induced by DC stimulation in the presence of amiodarone were of shorter duration (sustained-VTs >30 s/total VTs: 2/58, amiodarone vs 13/52, control), whereas those with lidocaine were of longer duration (22/73, lidocaine vs 14/58, control). Amiodarone caused prolongation of VT cycle length and destabilization of SW re-entry, which is characterized by marked prolongation of functional block lines, frequent wavefront-tail interactions near the rotation center, and considerable drift, leading to its early annihilation via collision with anatomical boundaries. Spiral wave re-entry in the presence of lidocaine was more stabilized than in control. In the anisotropic ventricular myocardium, amiodarone destabilizes SW re-entry facilitating its early termination. Lidocaine, in contrast, stabilizes SW re-entry resulting in its persistence.
authors.affiliation: Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Harumichi
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Haruo
authors.initials: H
authors.lastname: Honjo
authors.forename: Yuko S
authors.initials: YS
authors.lastname: Ishiguro
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Okuno
authors.forename: Masahide
authors.initials: M
authors.lastname: Harada
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takanari
authors.forename: Ichiro
authors.initials: I
authors.lastname: Sakuma
authors.forename: Kaichiro
authors.initials: K
authors.lastname: Kamiya
authors.forename: Itsuo
authors.initials: I
authors.lastname: Kodama
mesh_terms: D000200:Action Potentials; D000638:Amiodarone / Q000494:pharmacology*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D002304:Cardiac Pacing, Artificial; D004195:Disease Models, Animal; D022062:Electrophysiologic Techniques, Cardiac; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology; D006352:Heart Ventricles / Q000187:drug effects / Q000503:physiopathology; D007700:Kinetics; D008012:Lidocaine / Q000494:pharmacology*; D010477:Perfusion; D011817:Rabbits; D017180:Tachycardia, Ventricular / Q000188:drug therapy* / Q000503:physiopathology
chemical_list: D000889:Anti-Arrhythmia Agents; D008012:Lidocaine; D000638:Amiodarone