[Mexiletine in the treatment of ventricular arrhythmias (author's transl)].

The indication and efficacy of mexiletine is described in five patients. In four children the first signs of arrhythmias were seen a short time after viral infection. Two girls had numerous ventricular extrasystoles, which showed very promptly a positive reaction to mexiletine. Two patients had ventricular tachycardias beside ventricular premature beats. Because of signs of cardial insufficiency a 13 year old boy was defibrillated before his cardiac rhythm could be established with mexiletine. Because of ventricular tachycardias the second patient was treated with a combination of mexiletine and propranolol. Seven years after corrective operation of tetralogy of Fallot a nine year old boy showed ventricular extrasystoles. Because of a very low plasma concentration of mexiletine the therapy was without any effect. In all children, a long term ECG over 24 hours was deduced. To control the efficacy of mexiletine in all patients the plasma-concentration was determined. The therapeutic effective plasma concentration of mexiletine lays between 0.5 and 2,5 mcg/ml. This level can be reached by a daily dose of 12.5--16.2 mg/kg body weight.