Long QT syndrome is an abnormality of the heart's electrical system. The problem is due to defects in the heart muscle cell structures, called ion channels, which control the flow of potassium and sodium in and out of the heart’s cells. These electrical defects predispose individuals to a very fast cardiac rhythm (tachyarrhythmia or tachycardia) called torsade de pointes which leads to syncope and may cause sudden cardiac death. Long QT syndrome may be acquired or inherited. The acquired form is more common and is usually caused by the administration of medications. Inherited long QT occurs in 1 in every 5,000-7,000 individuals.