<unk>  <unk>  is a condition in which repolarization of the heart after a heartbeat is affected. It results in an increased risk of an irregular heartbeat which can result in fainting, drowning, seizures, or sudden death. These episodes can be triggered by exercise or stress. Some rare forms of<unk>  are associated with other symptoms and signs including deafness and periods of muscle weakness.<unk>  may be present at birth or develop later in life. The inherited form may occur by itself or as part of larger genetic disorder. Onset later in life may result from certain medications, low blood potassium, low blood calcium, or heart failure. Medications that are implicated include certain antiarrhythmics, antibiotics, and antipsychotics.<unk>  can be diagnosed using an electrocardiogram (EKG) if a corrected<unk>  interval of greater than 480–500 milliseconds is found, but clinical findings, other EKG features, and genetic testing may confirm the diagnosis with shorter<unk>  intervals. Management may include avoiding strenuous exercise, getting sufficient potassium in the diet, the use of beta blockers, or an implantable cardiac defibrillator. For people with<unk>  who survive cardiac arrest and remain untreated, the risk of death within 15 years is greater than 50%. With proper treatment this decreases to less than 1% over 20 years.<unk>  is estimated to affect 1 in 7,000 people. Females are affected more often than males. Most people with the condition develop symptoms before they are 40 years old. It is a relatively common cause of sudden death along with Brugada syndrome and arrhythmogenic right ventricular dysplasia. In the United States it results in about 3,500 deaths a year. The condition was first clearly described in 1957.
Long QT syndrome
Brugada syndrome
Short QT syndrome
Arrhythmogenic cardiomyopathy
Catecholaminergic polymorphic ventricular tachycardia
Opitz G/BBB syndrome
Jervell and Lange-Nielsen syndrome
Familial atrial fibrillation