Long Qt Syndrome

What is the long Q-T syndrome (LQTS)?

Long Q-T syndrome is an infrequent, hereditary disorder of the heart\'s electrical rhythm that can occur in otherwise-healthy people. It usually affects children or young adults.



When the heart contracts, it emits an electrical signal. This signal can be recorded on an electrocardiogram (ECG or EKG) and produces a characteristic waveform. The different parts of this waveform are designated by letters -- P, Q, R, S and T. The Q-T interval represents the time for electrical activation and inactivation of the ventricles, the heart\'s lower chambers. A doctor can measure the time it takes for the Q-T interval to occur (in fractions of a second), and can tell if it occurs in a normal amount of time. If it takes longer than normal, it\'s called a prolonged Q-T interval.



What are the symptoms of LQTS?



In the long Q-T syndrome, the above-described Q-T interval is prolonged. People with this syndrome are susceptible to an abnormally rapid heart rhythm (arrhythmia) called \"Torsade des pointes.\" When this occurs, the heart muscle can\'t contract effectively, and the normal volume of blood is reduced to the body and -- most important -- to the brain. If the brain is starved of oxygen, the person faints within seconds.



If the heart can\'t regain its normal rhythm, it may go into spasms that lead to a deadly arrhythmia called ventricular fibrillation. Without immediate emergency treatment, death follows within minutes.



People with this syndrome may show prolongation of the Q-T interval during physical exercise, intense emotion (such as fright, anger or pain), or by a startling noise.



In one type of inherited long Q-T syndrome, the person is also deaf. Studies of otherwise-healthy people with LQTS indicate that they had at least one episode of blacking out (fainting) by the age of 10. The majority also had a family member(s) with a long Q-T...