Long QT Syndrome

Posted by e-Medical PPT Wednesday, September 8, 2010
The long QT syndrome (LQTS) is a rare inborn heart condition in which delayed repolarization of the heart following a heartbeat increases the risk of episodes of torsade de pointes.This may lead to palpitations, fainting and sudden death due to ventricular fibrillation.LQTS can arise from mutation of one of several genes.These mutations tend to prolong the duration of the ventricular action potential (APD), thus lengthening the QT interval. LQTS can be inherited in an autosomal dominant or an autosomal recessive fashion.
All forms of the long QT syndrome involve an abnormal repolarization of the heart. The abnormal repolarization causes differences in the refractory period of the myocytes.After-depolarizations can be propagated to neighboring cells due to the differences in the refractory periods, leading to re-entrant ventricular arrhythmias.
Those diagnosed with long QT syndrome are usually advised to avoid drugs that would prolong the QT interval further.Administration of beta receptor blocking agents which decreases the risk of stress induced arrhythmias. Beta blockers are the first choice in treating Long QT syndrome.The effective form of arrhythmia termination in individuals with LQTS is placement of an implantable cardioverter-defibrillator (ICD). Alternatively, external defibrillation can be used to restore sinus rhythm.ICDs are commonly used in patients with syncopes despite beta blocker therapy, and in patients who have experienced a cardiac arrest.

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1 Response to Long QT Syndrome

  1. blogger 123 Says:
  2. I have prolonged QT which was found on ECG.

    This is due to a clinical pathway of Von Willebrands Type II B and also prolonged QT. The issue came to light with drugs namely Citalopram, Amitriptyline, Quinoric (new brand of Plaquenil. I am not allowed to take any drug which interfere with the QT interval.

    At the same time, I also had sinus tachycardia on echocardiogram.

    I have also 22q11.2 deletion syndrome/VCFS/DiGeorge syndrome and as part of that deletion, I have hypoparathyroidism/hypocalcaemia. Hypocalcaemia is also known to prolong the QT interval.

    Fiona

     

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