Rationale:

• Raising body temperature in hypothermic patients is essential to the success of antiarrhythmic agents.
• The drug of choice is amiodarone, which is effective in treating atrial fibrillation and ventricular arrhythmias, especially in patients with depressed left ventricular function.

Evidence:

• A randomized, controlled trial found that amiodarone was more effective than lidocaine in management of out-of-hospital cardiac arrests (171).
• Recommendations for advanced life support suggest the use of amiodarone after defibrillation, for hemodynamically stable ventricular tachycardia and wide-complex tachycardia, and as an adjunct to electrical cardioversion of refractory paroxysmal supraventricular tachycardias (106).
• Amiodarone is included in the 2000 advanced cardiovascular life-support guidelines as a possible agent for hemodynamically stable monomorphic VT, non-QT prolonged polymorphic VT, and VF/pulseless VT, and as the antiarrhythmic of choice for VF/pulseless VT. Amiodarone is classified as a IIb therapeutic intervention for all three arrhythmia categories, which makes it an acceptable, safe, and useful agent with fair to good evidence to support its use. In addition, amiodarone requires careful preparation and delivery to achieve safe and effective outcomes (106; 172). Amiodarone is safe in patients with structural heart disease and in patients with depressed left ventricle function.
• A study found that hypothermia induces a drop in serum potassium through redistribution. Aggressive replacement of potassium can result in hyperkalemia upon rewarming, resulting in potential cardiotoxicity (173).

Comments:

• Current American Heart Association recommendations do not address hypothermia-induced ventricular arrhythmias.
• There is considerable evidence to support the use of amiodarone for ventricular fibrillation or hemodynamically unstable ventricular tachycardia; however, its role in severely and moderately hypothermic patients remains undefined.
• Lidocaine is relatively contraindicated for management of ventricular tachycardia/fibrillation in hypothermic patients.
• Many of the causes of wide-complex tachycardia, ventricular tachycardia, and fibrillation should resolve by treatment of hypothermia and correction of any electrolyte and acid-base disturbances.