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Complications
By Mayo Clinic staffProlonged Q-T intervals may never cause any problems. However, physical or emotional stress may "trip up" a heart susceptible to prolonged Q-T intervals and cause the heart's rhythm to spin out of control, triggering life-threatening, irregular heart rhythms (arrhythmias) including:
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Torsades de pointes — 'twists of the points.' This arrhythmia is characterized by your heart's two lower chambers (ventricles) beating fast, making the waves on an ECG monitor look twisted. When this arrhythmia occurs, less blood is pumped out from your heart. Less blood then reaches your brain, causing you to faint suddenly and, often, without any warning.
If a torsades de pointes episode is short — lasting less than one minute — your heart can correct itself seconds later, and you regain consciousness on your own. However, if a torsades de pointes episode persists, it can lead to a life-threatening arrhythmia called ventricular fibrillation.
- Ventricular fibrillation. This condition causes the ventricles to beat so fast that your heart quivers and effectively ceases pumping blood. Unless your heart is shocked back into a normal rhythm by a device called a defibrillator, ventricular fibrillation can lead to brain damage and death. It's thought that long QT syndrome may explain some cases of sudden death in young people who otherwise appear healthy.
- Ackerman MJ, et al. Congenital long QT syndrome. In: Gussak I, et al. Electrical Diseases of the Heart; Genetics, Mechanisms, Treatment, Prevention. New York, N.Y.: Springer; 2008:462.
- Long QT syndrome. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/dci/Diseases/qt/qt_whatis.html. Accessed Feb. 10, 2012.
- Long QT syndrome. Heart Rhythm Society. http://www.hrsonline.org/PatientInfo/HeartRhythmDisorders/IDisorders/index.cfm. Accessed Feb. 10, 2012.
- Madias C, et al. Acquired long QT syndrome from stress cardiomyopathy is associated with ventricular arrhythmias and torsades de pointes. Heart Rhythm. 2011;8:555.
- Mauriello DA, et al. Holter monitoring in the evaluation of congenital long QT syndrome. Pacing & Clinical Electrophysiology. 2011;34:1100.
- Berul CI, et al. Acquired long QT syndrome. http://www.uptodate.com/index. Accessed March 9, 2012.
- Barsheshet A, et al. Genotype-specific QT correction for heart rate and the risk of life-threatening cardiac events in adolescents with congenital long-QT syndrome. Heart Rhythm. 2011;8:1207.
- Seslar SP, et al. Diagnosis of congenital long QT syndrome. http://www.uptodate.com/index. Accessed March 9, 2012.
- Anand RG, et al. The role of fish oil in arrhythmia prevention. Journal of Cardiopulmonary Rehabilitation and Prevention. 2008;28:92.
- Farnsworth MM, et al. When I go in to wake them ... I Wonder: Parental perceptions about congenital long QT syndrome. Journal of the American Academy of Nurse Practitioners. 2006;18:284.
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