[Torsade de Pointes with T wave alternans in a patient receiving moderate dose of chlorpromazine: report of a case].

A case is presented of Torsade de Pointes (TDP) with T wave alternans in a 31-year-old female receiving a moderate dose of chlorpromazine. She was treated in an another hospital for schizophrenia with chlorpromazine (100 mg daily) for several years and admitted to Fujisawa city hospital for numerous episodes of syncope. The electrocardiogram immediately after admission revealed a marked QTc prolongation to 0.81 seconds, T wave alternation without any obvious change in morphology of the QRS complex, and recurrent ventricular tachycardia called TDP. The T wave alternans and TDP were easily abolished by intravenous administration of a bolus of 50 mg lidocaine infusion. The QT interval however, remained prolonged. Physical examination, including cardiac examination, was normal. Serum potassium was 3.6/mEq. Chlorpromazine was discontinued immediately after admission and no further episodes of TDP were seen after the first day. After the QT interval returned to almost normal, chlorpromazine (50 mg daily) was re-administered. Two days after the re-administration, the electrocardiogram revealed marked QT interval prolongation with prominent T waves. Psychotropic drugs, such as chlorpromazine, prolong the QT interval and cause TDP. Chlorpromazine appears to have been responsible for TDP and the T wave alternans in this case. TDP caused by a moderate dose of chlorpromazine has not been previously reported. Lone T wave alternans unaccompanied by changes in the QRS complex is a rare phenomenon and the mechanism underlying T wave alternans remains unknown.