What is the definition of Long QT Syndrome?

Long QT syndrome is a disorder of the heart’s electrical activity that can cause sudden, uncontrollable, and irregular heartbeats (arrhythmia), which may lead to sudden death. Long QT syndrome can be detected by electrocardiogram (EKG). It can be caused by a variety of different gene mutations (changes). It can also be acquired (noninherited) and may be brought on by certain medicines and other medical conditions.

What are the causes for Long QT Syndrome?

Acquired long QT syndrome can be caused by certain medicines and medical conditions. Some medications that cause long QT syndrome include antihistamines and decongestants, antibiotics, antidepressants, and cholesterol-lowering medicines. Examples of medical conditions that can cause long QT syndrome include excessive diarrhea or vomiting and certain thyroid disorders.Inherited forms of long QT syndrome are caused by changes in genes that control the heart muscle’s electrical activity. Inherited long QT syndrome may be isolated (occur alone without other associated symptoms) or be due to a genetic syndrome, such as Romano-Ward syndrome, Jervell Lang-Nielsen syndrome, Anderson-Tawil syndrome, and Timothy syndrome.

What are the symptoms for Long QT Syndrome?

Signs and symptoms of the arrhythmias experienced by people with long QT syndrome includes unexplained fainting, seizures, drowning or near drowning, and sudden cardiac arrest or death. You can read more about these and other symptoms of long QT syndrome on the National Heart Lung and Blood Institute's Web site by clicking here.