7 November 2010

Romano-Ward Syndrome (LQT1 to LQT6)

Romano-Ward Syndrome Features:
  • Major variant of long QT syndrome (abnormality on ECG - see opposite).
  • Can lead to ventricular tachyarrhythmias.
  • May lead to seizures, fainting, or sudden cardiac death.
Romano-Ward Syndrome Genetics:
  • Inherited in an autosomal dominant pattern.
  • Most common form of inherited long QT syndrome.
  • Estimated to affect ~ 1 in 5,000 people, though may be more common than this because of non-symptomatic patients.
  • 6 main forms noted (LQT1, LQT2, LQT3, LQT4, LQT5, LQT6).
  • Associated with mutations in the ANK2, KCNE1, KCNE2, KCNH2, KCNQ1, and SCN5A genes.
  • The proteins made by these genes lead to the proper formation of channels that transport positively-charged ions, such as potassium & sodium, in and out of cells.
  • The ANK2 gene product has a function to ensure that proteins, particularly ion channels, are inserted into the cell membrane properly & appropriately.
Romano-Ward Syndrome Treatment:
  • There is evidence that an imbalance between the right and left sides of the sympathetic nervous system may have a function in producing this symptomatic syndrome.
  • A left stellate ganglion block, which shorten the QT interval, may redress this balance.
  • In patients who respond to the stellate ganglion block may obtain lasting improvement with a surgical ganglionectomy.
  • Drugs which prolong the QT interval should be avoided.
  • Drugs which reduce serum potassium or magnesium should be avoided.
  • Placement of an implantable cardioverter-defibrillator (ICD) is another treatment option in high risk patients.
  • Competitive sport participation should be avoided for patients with the diagnosis established by means of genetic testing only.
  • Beta-blocker therapy - ie propranolol or nadolol, reduce the risk or lethality of cardiac events.

Image: from Genotype and Severity of Long QT Syndrome. Jeffrey A. Towbin, Zhiqing Wang & Hua Li. © Drug Metabolism and Disposition (April 2001)
Tags: ANK2 - Beta-blocker - Ganglionectomy - ICD - KCNE1 - KCNE2 - KCNH2 - KCNQ1 - Long QT Syndrome - QT Interval - Romano-Ward Syndrome - SCN5A - Stellate Ganglion - Sympathetic Nervous System - Ventricular Tachyarrhythmias
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