Congenital long QT syndrome.

Long QT syndrome (LQTS) can be asymptomatic-identifiable as an incidental finding on electrocardiogram-or it can present with palpitation, syncope, seizures, or sudden cardiac death. LQTS is characterized by a prolonged QT interval, which can be associated with a specific form of polymorphic ventricular tachycardia known as torsade de pointes. Other electrocardiogram changes in LQTS include T-wave abnormalities, particularly bifid T waves, U waves, and T-wave alternans. The precipitating factors of LQTS include electrolyte abnormalities, bradyarrhythmias, medications (such as antiarrhythmic drugs, antibiotics, antipsychotics, and antihistamines), and myocardial ischemia. The authors report a case of LQTS in a 47-year-old woman with no other significant cardiac history.