ABSTRACT
Torsade de pointes is a polymorphic ventricular tachycardia, associated with prolonged QT interval and characterized by twisting of the mean electrical axis of the QRS complexes around an isoelectric line. The long QT syndrome can be divided into two categories, congenital and acquired. The congenital long QT syndrome may be caused by some gene mutation, whereas the acquired form is usually associated with drugs and electrolyte imbalance. It usually remains asymptomatic or causes presyncope, although it may degenerate into ventricular fibrillation and may cause sudden death. The different presentation depends on the polymorphism that characterizes genotypic and phenotypic expression of proteic channel subunits, and on drug toxicity that provoke subunit dysfunction. The case report presented here is an example of prolonged QT interval syndrome in a patient with cocaine abuse and electrolyte disturbances.
