What is Long Q-T Syndrome?

Long Q-T syndrome is a rare disorder of the heart's electrical system that can happen in otherwise healthy people. Its name comes from the way the hearts electrical activity is recorded during an electrocardiogram (ECG or EKG). The electrical activity that is recorded produces a characteristic pattern and the different parts of the pattern are labeled with the letters P, Q, R, S and T. The space between the Q and the T (the Q-T interval) represents the time it takes for the electrical signal to pass through the lower chambers of the heart (the ventricles). If it takes longer than normal, it is diagnosed as a prolonged Q-T interval.

People with Long Q-T syndrome do not necessarily have a prolonged Q-T interval all of the time. It is possible for patients to have an ECG with a normal Q-T interval. People with this syndrome may show prolongation of the Q-T interval during physical exercise, while experiencing intense emotion or when startled. In one type of inherited long Q-T syndrome, the person is also deaf.

Long Q-T syndrome is often inherited and is usually present from birth (congenital). It can also be caused by certain medications, or it can result from a stroke or some other neurological disorder.

Symptoms
Some people with long Q-T syndrome often have no symptoms. If there are symptoms, they may include fainting and abnormal rate and/or rhythm of the heart beat (arrhythmia). If not detected and treated, a small minority of arrhythmias may be fatal.

Studies of otherwise healthy people with long Q-T syndrome show that many have had at least one episode of fainting by the age of 10. The majority also have a family member(s) with a similar disorder. Advise your doctor if anyone in your family has had repeated episodes of fainting or if there is a history of sudden death.

Diagnosis
Long Q-T syndrome is diagnosed by an electrocardiogram (ECG or EKG), is a printed record of your heart's electrical activity that provides information about its rhythm, chambers, heart damage and other abnormalities.

Treatment
Your doctor may prescribe medication or surgery, as well as recommending lifestyle changes.

Medication
Beta blockers reduce how much oxygen your heart needs by slowing your heart rate or lowering your blood pressure.

Surgery
If Long Q-T Syndrome causes uncontrolled ventricular fibrillation, an implantable cardioverter defibrillator (ICD) may be required.

Lifestyle
You can lower your risk of heart disease by knowing and controlling your blood pressure, diabetes and blood cholesterol. It is also important to lead a healthy lifestyle by being smoke-free and physically active, eating a healthy diet that is lower in fat, especially saturated and trans fat, achieving and maintaining a healthy weight, limiting alcohol use and reducing your stress.

Last reviewed April 2007.