What is Long QT Syndrome?

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  • Written By: wiseGEEK Writer
  • Edited By: Niki Foster
  • Last Modified Date: 13 January 2019
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Long QT syndrome is a disruption in the heart’s normal rhythms that can cause fainting during prolonged or strenuous activity, or during extreme excitation. In the worst-case scenarios, undiagnosed long QT can result in sudden arrhythmia death syndrome. Most people are used to occasionally reading about an otherwise healthy child who dies suddenly during an athletic event, without apparent cause. In these cases, the child has usually suffered from long QT, but has never shown symptoms that would suggest the condition in the past.

Family history of ventricular tachycardia, a series of irregular heart beats originating from the rhythm patterns of the left or right ventricle, is the best indication that a child may be vulnerable to long QT. During the T wave pattern of rhythm, a second and incorrect signal can be sent to the heart, causing the ventricles to beat in an irregular pattern, which can cause either collapse or heart attack.


In some cases, long QT is associated with other heart defects and can therefore be more easily diagnosed. Children with other heart defects are likely to be watched more closely for signs of arrhythmias than children who seem otherwise completely healthy. Often children with multiple defects undergo yearly testing and wear a holter monitor for 24 hours that can detect abnormal rhythms. They are also likely to have electrocardiograms (EKGs) and stress tests on a more regular basis. In most cases, such tests would not be considered for a healthy child.

If, however, there is family history of ventricular tachycardia or sudden arrhythmia death, this should be brought to the attention of the child’s pediatrician. Though long QT is quite rare, overlooking the possibility of its presence can lead to tragic consequences. A pediatric electrophysiologist, a cardiologist who specializes in abnormal heart rhythms, will probably evaluate a child with suspected long QT. Evaluating and diagnosing long QT has become much easier in the past few years due to understanding of genetic malformations that may cause the disorder. Mutations of Chromosomes 3, 7 and 11 can cause potassium and sodium ions to be out of balance, resulting in long QT.

Treatment generally involves giving beta-blockers, but frequent arrhythmias may require the placement of a defibrillator for greater control. When long QT has been undiagnosed, the best protection for children is to have trained professionals present who know how to use a portable defibrillator. Defibrillator training is no more difficult than typical CPR, and a coach or coaching assistant can easily acquire this training through the Red Cross or various other sources.

Parents who have lost children to long QT have become strong advocates for programs that would fund defibrillators and defibrillator training in all schools throughout the US. Some schools have been quick to respond to this need, while others are still quite behind in this area. The difference in survival of a long QT episode in which a defibrillator is employed is significant. Often, CPR is not enough to revive a child with long QT, and when emergency workers arrive, it is too late.

Given that we have the technology to quickly shock the heart back into normal sinus rhythm, and that portable defibrillators run under 1,000 US dollars (USD), acquiring them for schools and athletic teams should not be all that difficult. Parent advocates, however, have often met with resistance on the part of administrators, and must look outside the school for funding of equipment that can make the difference between life and death for a child suffering a long QT episode.



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