The effect of amiodarone on the ventricular fibrillation threshold.
We evaluated the antifibrillatory effect of two different doses of amiodarone after cardiac arrest with a cardiopulmonary resuscitation (CPR) model in 19 pigs. Ventricular fibrillation was induced by pacing the right ventricle using a primary drive train at a cycle length of 270 msec for 8 beats. The minimum current strength necessary to induce sustained ventricular fibrillation was defined as the ventricular fibrillation threshold (VFT) measured in mA. Three VFT determinations were made at baseline, followed by 9 minutes of continuous CPR with two determinations of VFT, and three after stabilization. The pigs were placed into one of three groups: amiodarone 2 or 5 mg/kg, or placebo. The average poststabilization VFT in each group was compared with the average baseline VFT. Pigs receiving amiodarone 2 mg/kg had significantly higher VFT after stabilization than at baseline (22.88+/-12.76 to 27.10+/-10.18 mA, p=0.048), as did those receiving 5 mg/kg (17.03+/-7.01 to 28.08+/-11.58 mA, p=0.002). The deltaVFT was significantly greater with amiodarone 5 mg/kg than with vehicle (placebo), but not with 2 mg/kg. There were no changes in VFT in any group during CPR versus baseline. When active treatments were combined, the trend was toward better survival in the amiodarone groups (13/13) compared with the placebo group (4/6, p=0.076).
Chen
B P
BP
Drug Information Center, Hartford Hospital, Connecticut 06102-5037, USA.
White
C M
CM
Fan
C
C
Kluger
J
J
Chow
M S
MS
D000638:Amiodarone / Q000494:pharmacology*; D000818:Animals; D001775:Blood Circulation / Q000187:drug effects; D001784:Blood Gas Analysis; D016887:Cardiopulmonary Resuscitation; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D012016:Reference Values; D013552:Swine; D014665:Vasodilator Agents / Q000494:pharmacology*; D014693:Ventricular Fibrillation / Q000188:drug therapy / Q000503:physiopathology*; D016276:Ventricular Function / Q000187:drug effects
D014665:Vasodilator Agents; D000638:Amiodarone