Clinical features and management of digitalis poisoning--rationale for immunotherapy

The intensity of gastrointestinal and visual symptoms together with hyperkalemia and the characteristic ECG features make diagnosis of acute digitalis intoxication relatively easy. Death results mainly from ventricular fibrillation or from ventricular asystole or pump failure. Mesenteric infarct may also occur in elderly patients. Previous assessment of outcome has shown that mortality increases in patients exhibiting five prognostic factors: 1) advanced age; 2) heart disease; 3) male sex; 4) high-degree atrioventricular block; 5) hyperkalemia. Conventional treatment includes gastric lavage, activated charcoal and supportive care. First-line antiarrhythmic therapy is usually atropine, because of bradycardia-induced arrhythmia. Ventricular pacing is a toxicodynamic treatment that may be helpful in both bradycardia-induced arrhythmia and high-degree atrioventricular block. Pacing is difficult to handle and can result in serious adverse effects. Immunotherapy has two advantages. First, a strong toxicodynamic effect due to quick reversal of digitalis-induced dysrhythmias, hyperkalemia, and myocardial depression, by reactivation of membrane ATPases. Second, a toxicokinetic effect due to accelerated renal excretion of Fab-digitalis complexes. Since this therapy is well tolerated and efficient, we recommend early administration of Fab fragments as soon as poor prognostic factors are identified.