Effects of amiodarone in a swine model of nortryptiline toxicity

Abstract

Antiarrhythmics can have devastating effects in cardiotoxic poisonings. Amiodarone is recommended for treatment of wide complex tachycardia, but its hemodynamic effects in wide complex tachycardia induced by tricyclic antidepressant poisoning are unknown. The objective of this study was to compare the effects of sodium bicarbonate, amiodarone, and normal saline in treating wide complex tachycardia secondary to nortriptyline poisoning. This unblended randomized controlled animal study involved 18 anesthetized, intubated pigs with arterial and venous lines. Nortriptyline (2 mg/mL) was infused at 20 mg/min until the onset of toxicity, defined as a systolic blood pressure < or =50 mmHg or QRS > or =120 ms. At that point, the pigs were randomized into three groups of six. Group I received 0.9% normal saline, 10 ml/kg. Group II received hypertonic sodium bicarbonate, 1 mEq/kg. Group III received amiodarone, 15 mg/kg. The pigs were observed until death or survival at 60 minutes. After treatment, the changes in QRS were as follows: Group I, -2.0 ms; Group II, -33.0 ms; Group III, -21.7 ms. ANOVA demonstrated no significant difference between the groups (p = 0.28). Mean arterial pressures 10 minutes after treatment were as follows: Group I, 19.4 mmHg; Group II, 23.7 mmHg; Group III, 12.5 mmHg. Based on ANOVA, there was no significant difference between any of the groups (p = 0.50). In this model of nortriptyline poisoning, the administration of amiodarone to correct wide complex tachycardia did not have a harmful effect.