Malignant familial long QT syndrome.
We report a family with congenital long QT syndrome, an inherited disorder of myocardial repolarization in which affected individuals have prolongation of corrected QT interval on the electrocardiogram and a tendency to develop ventricular arrhythmia, leading to syncope, convulsion or sudden death. Our family is characterized by several affected members (11/16), early onset of symptoms, malignant course prior to diagnosis and good response to beta-blocker therapy. The genetic basis of long QT syndrome has been traced to defective proteins encoding cardiac ion channels. Diagnosis is based on an unexplained prolongation of QT interval >0.45 second in the presence of suggestive symptoms or evidence, or both of a familial pattern. Beta-adrenergic blocker therapy gives symptomatic relief in 80%-85% of patients. Precipitating factors like vigorous exercise especially swimming and exposure to significant emotional or auditory stimuli should be avoided. Occasional patients require in addition, a demand cardiac pacemaker, left cardiac sympathectomy or an implantable cardioverter-defibrillator, or both. Regular follow up is mandatory even after subsidence of symptoms.
Subramanyan
Raghavan
R
Department of Pediatric Cardiology, Royal Hospital, Muscat, Sulanate of Oman. ragusha@omantel.net.om
Venugopalan
Poothirikovil
P
D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003241:Consanguinity; D006801:Humans; D007223:Infant; D008133:Long QT Syndrome / Q000151:congenital* / Q000188:drug therapy / Q000235:genetics; D008297:Male; D011433:Propranolol / Q000627:therapeutic use
D000319:Adrenergic beta-Antagonists; D011433:Propranolol