title: Longitudinal analysis of the depressive effects of intravenous amiodarone on depolarization and repolarization: a case report.
abstract: Intravenous amiodarone (AMD) induces multiple antiarrhythmic effects via blocking of Na(+), Ca(2+), and IKr channels, and beta receptors. A patient on chronic dialysis was administered AMD for nonsustained ventricular tachycardia after successful cardiopulmonary resuscitation. QT prolongation occurred 5 h after AMD administration. AMD was withdrawn at 24 h because of prolonged QTc interval (716 ms), which persisted for a further 48 h (661 ms). Ventricular premature contraction (VPC) was significantly decreased at 7h; however, VPC increased again after discontinuing AMD. Depolarization changes induced by the Na(+)-channel blocking action of AMD were analyzed. There was increasing filtered QRS-duration and duration of low-amplitude signals at voltage <40 µV, and decreasing root-mean-square voltage of signals in the last 40 ms of ventricular late potentials (LPs) within 7 h. However after stopping AMD, LPs were reversed. The blood concentration of AMD reached the effective level within 10 min but decreased immediately to an ineffective level. Onset and disappearance of the VPC-inhibiting effect corresponded to the depressive effect on depolarization but not with the increase in the prolonged repolarization effect and blood concentration. Even if the QT interval is sufficiently prolonged, the Na(+)-channel blocking action is required for AMD to induce the antiarrhythmic effect.
authors: Department of Cardiology, Tokai University School of Medicine, 143 Shimokasuya, Isehara 259-1193, Kanagawa, Japan. ko1@is.icc.u-tokai.ac.jp
authors: Koichiro
authors: K
authors: Yoshioka
authors: Mari
authors: M
authors: Amino
authors: Atsushi
authors: A
authors: Matsuzaki
authors: Makiyoshi
authors: M
authors: Shima
authors: Toshiharu
authors: T
authors: Fujii
authors: Shigetaka
authors: S
authors: Kanda
authors: Yoshiaki
authors: Y
authors: Deguchi
authors: Itsuo
authors: I
authors: Kodama
authors: Teruhisa
authors: T
authors: Tanabe
mesh_terms: D000638:Amiodarone / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology; D016887:Cardiopulmonary Resuscitation; D003864:Depression, Chemical; D015716:Electrocardiography, Ambulatory; D006801:Humans; D007262:Infusions, Intravenous; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D026941:Sodium Channel Blockers; D017180:Tachycardia, Ventricular / Q000503:physiopathology* / Q000628:therapy*; D013997:Time Factors; D016276:Ventricular Function / Q000187:drug effects
chemical_list: D000889:Anti-Arrhythmia Agents; D026941:Sodium Channel Blockers; D000638:Amiodarone