TORSADE de POINTES, QT, AND ANTIPSYCHOTIC DRUGS

Walter V. Vieweg, M.D., Box 0710, Richmond, VA 23298

Certain drugs, including psychotropic drugs, may cause clinically significant electrocardiographic QT interval prolongation and lead to dizziness, palpitations, and syncope. Cardiac arrhythmias associated with QT interval prolongation include ventricular tachycardia of the torsade de pointes type and ventricular fibrillation. Recent withdrawal and reclassification of numerous non-psychotropic and psychotropic drugs has raised concern for the practicing psychiatrist about drug-induced cardiac arrhythmias and sudden death. The electrical circuits within the heart coordinate chamber contractions to optimize ejection of blood into the system and pulmonary circulations. The QT interval consists of both ventricular depolarization and repolarization with time to repolarize making up the major part of the QT interval. Many psychotropic drugs may disturb cardiac potassium ion channels during repolarization, lengthen the QT interval, provoke serious cardiac arrhythmias of the torsade de pointe type, and be associated with sudden cardiac death.