Long QT syndrome (patient information)
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Long QT syndrome |
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Long QT syndrome On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief:; Charmaine Patel, M.D. [2]
Overview
Long QT syndrome is a condition resulting in an abnormality in the way electrical impulses are conducted within the heart. It can cause sudden cardiac arrhythmias in response to several stimuli, including exercise, stress, pharmacological interventions, heart disease, and neurological disorders. Arrhythmias are abnormalities in the rhythm of the heartbeat. These arrhythmia's can be dangerous and fatal, but not everyone with long QT syndrome will have arrhythmias.
What are the symptoms of Long QT syndrome?
- Seizures - if the heart continues to beat abnormally, the brain can become deprived of oxygen, which can then cause seizures.
- Fainting - fainting or syncope is the most common symptom in persons with long QT syndrome. The fainting can occur spontaneously without warning, or in response to certain stressors such as emotional stress, exercise, excitement or loud noises. Often when people are about to faint, they may experience lightheadedness, heart palpitations, blurred vision or weakness.
- Sudden death - in some circumstances a fatal arrhytmia that is not quickly intervened on, may cause sudden death.
What causes Long QT syndrome?
Long QT syndrome is caused by a problem with the electrical activity in the heart. After it beats, the heart has to recharge in preparation for the next beat which will pump blood to the body. In long QT syndrome, the heart takes longer than normal to recharge.
Who is at highest risk?
- Persons with a history of repeated fainting, accidents, seizures or a history of cardiac arrest.
- Family members of persons with repeated fainting, accidents, seizures or a history of cardiac arrest.
- Persons who are on certain medications that are known to cause a prolonged QT interval on electrocardiogram.
- Persons who are first degree relatives of people with know long QT syndrome.
- Persons who suffer from anorexia nervosa, or who have low levels of magnesium, calcium or potassium in their blood.
Diagnosis
There are certain tests that will help in the diagnosis of long QT syndrome.
- An electrocardiogram will measure the electrical activity of the heart, which your doctor will be able to read and interpret. You may need to have this test done while exercising or running on a treadmill.
- Ambulatory EKG monitoring is used to monitor your heart for abnormal rhythms during a 24 hour period. The monitor will record the electrical activity of your heart.
- Event EKG monitoring is similar to an ambulatory EKG, but you may need to wear the EKG recorder for days to weeks.
When to seek urgent medical care?
See your doctor if you experience fainting, shortness of breath, palpitations, seizures or any of the other symptoms of long QT syndrome. Also seek medical care if you have an illness which can cause low levels of potassium in the blood, such as illnesses which cause vomiting and diarrhea.
Treatment options
Lifestyle changes and medications can be used to help treat long QT syndrome. These are:
- Avoiding high intensity physical activity or stress.
- Including more potassium in the diet, with the help of a doctors supervision.
- Certain heart medications, such as beta blockers will prevent people from going into sudden cardiac arrest.
- Certain medical devices, such as an implantable cardiac difibrillator or a pacemaker can help to regulate the rhythm of the heart.
Where to find medical care for Long QT syndrome?
Directions to Hospitals Treating Condition
Prevention
Certain medications should be avoided if you have long QT syndrome, so that you do not worsen your condition. These medications include certain appetite suppressants, decongestants, and antibiotics such as erythromycin. Illicit drugs such as cocaine and amphetamines can be even more dangerous in persons with long QT syndrome. For a full list of drugs to avoid in long QT syndrome, click here.
You should also seek medical care if you have an illness that could cause low levels of potassium in your blood, such as illnesses causing vomiting and diarrhea. Certain medications such as diuretics can also lower the levels of potassium in your blood, and need to be avoided.
What to expect (Outlook/Prognosis)?
People who are treated with lifestyle modifications and medications live longer than those who are not. For people who are not treated, half of them, mostly those with the inherited form of long QT syndrome, will die within 10 years.
Possible complications
Long QT syndrome can result in fatal heart arrhythmias and death.