Intraoperative complications in patients receiving amiodarone: characteristics and risk factors

This article reviews amiodarone's adverse cardiovascular properties, concentrating on those in surgical patients, and evaluates several potential risk factors. Amiodarone has negative inotropic and chronotropic properties as well as peripheral vasodilating properties that may manifest as bradycardia, reduced cardiac output, and hypotension. These reactions are clinically important during surgery, because of resistance to pharmacologic resuscitation and an increased mortality rate. Potential risk factors include ventricular dysfunction, rapid infusion rate, hypocalcemia, cardiopulmonary bypass, general anesthesia, concurrent negative inotropic or chronotropic drugs, and an elevated serum amiodarone or desethylamiodarone concentration. The following measures may decrease the risk of intraoperative adverse reactions in amiodarone-treated patients. The serum calcium concentration should be at the physiologic level and the serum amiodarone and digoxin concentrations should be in the therapeutic range. Negative inotropic and chronotropic agents should be discontinued when possible. A temporary cardiac pacemaker may prevent intraoperative hypotension due to bradycardia. Amiodarone may be discontinued before surgery to minimize the risk of intraoperative complications, but this decision should balance the potential for amiodarone-associated intraoperative complications against the risk of arrhythmia recurrence and the delay of surgery.