A patient with sustained ventricular tachycardia: identification of a responder to amiodarone using signal-averaged electrocardiogram.
A 75-year-old man suffered sustained ventricular tachycardia with syncopal attack. Ventricular tachycardias appeared repeatedly, and an electrical defibrillator was used after an anti-arrhythmic drug, such as lidocaine or mexiletine, proved ineffective. The tachycardias had multiple origins, and the signal-averaged electrocardiogram (SAECG) showed ventricular late potential before the administration of amiodarone. After administration, the filtered QRS and duration of the late potential increased, but the recurrence of tachycardias was suppressed. The reason for this is thought to be that amiodarone blocked the sodium channel and delayed conduction, consequently blocking reentry, because amiodaron has antiarrhymic properties with a prolongation of refractoriness and minimal effect on conduction velocity in ventricular myocardium, and inhibits sympathetic activity, and blocks L-type calcium channel besides the depression of the fast sodium channel. In this case, SAECG predicted to some degree whether or not this patient's ventricular tachycardia would respond to amiodarone.
Department of Digestive and Cardiovascular Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.
Ayaka
A
Kobayashi
Masahiro
M
Nomura
Yuko
Y
Sawa
Takashi
T
Kawaguchi
Kunihiko
K
Koshiba
Koji
K
Yamaguchi
Tomohito
T
Kawano
Tetsuzo
T
Wakatsuki
Tomotsugu
T
Tabata
Akiyoshi
A
Nisikado
Susumu
S
Ito
Yutaka
Y
Nakaya
D000368:Aged; D000638:Amiodarone / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D004562:Electrocardiography / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D012815:Signal Processing, Computer-Assisted; D017180:Tachycardia, Ventricular / Q000188:drug therapy* / Q000503:physiopathology
D000889:Anti-Arrhythmia Agents; D000638:Amiodarone