[Clinico-pharmacological case (2). Bradycardia and ventricular tachycardia of the torsades de pointes type as a side effect of vasopressin: 3 case reports].

: We present three patients with ornipressin-induced bradycardia, one of which developed also ventricular tachycardia of the torsade de pointes type. All three patients were treated with this vasopressin derivative because of bleeding esophageal varices due to portal hypertension in liver cirrhosis. Bradycardia ceased after discontinuing ornipressin therapy. One patient was treated successfully with atropine, one with isoprenalin and magnesium (he had to be defibrillated); the third patient recovered after cessation of ornipressin administration. Bradycardia is a known but rarely reported side effect of vasopressin and its derivatives. Animal studies suggest that this effect is due to its cardiodepressive action and also to a vagus-mediated reflex following vasopressin-induced increase in blood pressure. When injected directly into the ventricles of the brain, vesopressin leads to a decrease of the heart rate without affecting blood pressure; however, it remains unclear whether this mechanism is responsible for bradycardia after intravenous administration. Careful monitoring is essential during the treatment with vasopressin and its derivatives.