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Long QT syndrome (LQTS) is a rare inherited or acquired heart condition in which delayed repolarization of the heart following a heartbeat increases the risk of episodes of ''torsades de pointes'' (TdP, a form of irregular heartbeat that originates from the ventricles). These episodes may lead to palpitations, fainting, and sudden death due to ventricular fibrillation. Episodes may be provoked by various stimuli, depending on the subtype of the condition. The condition is named for the appearance of the electrocardiogram (ECG/EKG) on which a prolongation of the QT interval occurs. Normally, the QT interval duration is between 350 and 440 milliseconds.〔 In some individuals, the QT prolongation occurs after the administration of certain medications, which may be dangerous.〔 In addition to medications, long QT syndrome can be acquired from malnutrition leading to low blood potassium or low blood magnesium, as in anorexia nervosa. == Signs and symptoms == Many people with long QT syndrome have no signs or symptoms. Some people may experience the following symptoms: *Fainting (or syncope). This may occur when the patient is emotional or physically stressed. It is unusual in QT syndrome to have any signs before the person actually faints. *Seizures *Sudden death. If there is sudden death, and doctors suspect long QT syndrome as the cause, they may recommend that the family members of the deceased get tested for the disease. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Long QT syndrome」の詳細全文を読む スポンサード リンク
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