Risk factors of ventricular fibrillation during rapid amphotericin B infusion.

Amphotericin B causes reversible concentration-dependent loss of intracellular potassium in vitro and hyperkalemic ventricular arrhythmias in dogs. Hyperkalemic ventricular arrhythmias associated with amphotericin B infusion have not been well documented in humans. Ventricular fibrillation with progressive hyperkalemia (up to 8 to 8.4 meq/liter) occurred twice in an anuric patient during rapid infusion of high-dose amphotericin B (1.4 mg/kg over 45 min). The peak amphotericin B concentration in serum at the end of infusion was 6.7 micrograms/ml. Prolonged infusion (3 h) and concurrent hemodialysis each prevented the development of hyperkalemia and ventricular arrhythmia. In two anuric patients receiving 4-h infusions of amphotericin B during dialysis (0.7 and 1.0 mg/kg), peak amphotericin B concentrations in serum were lower, 1.6 +/- 0.1 and 2.7 +/- 0.7 micrograms/ml, respectively; serum potassium levels were maintained in the normal range; and venous access for outpatient therapy was convenient. Peak concentrations of amphotericin B in serum were also lower (1.7 +/- 0.7 micrograms/ml) in eight patients with normal renal function who received lower doses (0.7 +/- 0.2 mg/kg) over 45 min; there were only slight increases in the serum potassium level (from 3.9 +/- 0.9 to 4.4 +/- 0.6 meq/liter, P less than 0.05). We recommend that rapid infusion of amphotericin B not be used in patients with impaired potassium excretion unless accompanied by hemodialysis and careful potassium monitoring.