What is the role of prolonged QT interval in the pathogenesis of torsade de pointes?

Updated: Jan 31, 2017
  • Author: Jatin Dave, MD, MPH; Chief Editor: Mikhael F El-Chami, MD  more...
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Answer

Answer

The association between torsade and a prolonged QT interval has long been known, but the mechanisms involved at the cellular and ionic levels have been made clearer in approximately the last decade. The abnormality underlying both acquired and congenital long QT syndromes is in the ionic current flow during repolarization, which affects the QT interval.

A variety of changes in ionic current can result in the common effect of decreased repolarizing current, reflected in a long QT, and these changes can secondarily lead to subsequent depolarizing currents and sometimes action potentials, termed afterdepolarizations. This leads to a further delay in repolarization and causes early afterdepolarization (EAD), the triggering event for torsade.


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