Review Question - QID 100738

The patient likely suffers from Jervell and Lange-Nielson syndrome, an autosomal recessive, congenital long-QT syndrome accompanied by neurosensory deafness. Patients with QT-interval prolongation are at risk for syncopal episodes and sudden cardiac arrest from torsades de pointes.

Torsades de pointes (torsades) is the most prominent arrhythmia associated with long QT syndromes. Torsades is characterized by a rapid, polymorphic ventricular tachycardia with changes in cycle length, axis, and morphology that appear to twist in patterns around a central axis on ECG. Torsades may degenerate into ventricular fibrillation.

Meyer et al. review the relationship between long QT syndrome and sudden cardiac deaths. Most cardiac events in these individuals are precipitated by emotional stress or vigorous exercise. Patients with recurrent syncope during exertion or family histories of sudden death should be evaluated for long QT syndrome. The mainstays of treatment have been beta blockers, potassium supplements, and implantable defibrillators.

Crotti et al. review congenital long QT syndrome. Genetic causes of long QT syndrome have been identified in individuals with a familial history of sudden cardiac death. Mutations in genes that encode the cardiac ion channel subunits prolong cardiac action potential durations leading to symptomatic long QT syndrome. The prognosis of the disease is generally good in patients who have been diagnosed and receive treatment. Jervell and Lange-Nielsen syndrome is an exception to this as patients become symptomatic at a much younger age, often requiring implantable defibrillators before they reach their teens.

Figure A depicts the characteristic ECG pattern seen with torsades.

Incorrect Answers:
Answers 1, 2, 3, and 5 are not associated with QT-interval prolongation.