Long QT Syndrome - At a Glance


Description

What is Long QT Syndrome?
Long QT syndrome (LQTS) is a disorder of the heart's electrical activity that may cause dangerous heart rhythms in response to exercise or stress.
Learn more.

Causes and Risk Factors

What are the causes and risk factors of Long QT Syndrome?
LQTS is a rare condition that is usually inherited, but may also be acquired by certain medicines and conditions. Learn more.

Symptoms

What are the symptoms of Long QT Syndrome?
The signs and symptoms of LQTS-related arrhythmias include unexplained fainting or seizures, drowning or near drowning (due to fainting while swimming), sudden cardiac arrest and sudden death. Learn more.

Diagnosis

How is Long QT Syndrome diagnosed?
To diagnose LQTS, your doctor will consider your electrocardiogram (ECG or EKG) results, your personal and family medical histories, and genetic test results. Learn more.

Treatment

How is Long QT Syndrome treated?
Treatments for LQTS include lifestyle changes, medicines, implanted medical devices, and surgery to regulate your heartbeat. Learn more.

Success Stories

What is it like to have Long QT Syndrome?
Patients and families with Long QT Syndrome share their treatment stories. Learn more.


 

Description

What is Long QT Syndrome?
Long QT syndrome (LQTS) is a disorder of the heart's electrical activity. It may cause you to develop a sudden, uncontrollable, and dangerous heart rhythm in response to exercise or stress.

Arrhythmias also can develop for no known reason in people who have LQTS. Not everyone who has LQTS develops dangerous heart rhythms. However, if one does occur, it may be fatal.

The term "long QT" refers to an abnormal pattern seen on an electrocardiogram (ECG or EKG). An ECG is a test that detects and records the heart's electrical activity. The QT interval, recorded on the ECG, corresponds to the time during which the ventricles lower chambers of your heart) are triggered to contract and then build the potential to contract again. 

Illustration of Long QT Syndrome

With each beat, the heart contracts and relaxes. If the heart takes longer than usual to contract and relax, there is a wider space between the Q and T. This could mean that the person has long QT syndrome.

The timing of the heartbeat's electrical activity is complex, and the body carefully controls it. Normally the QT interval of the heartbeat lasts about a third of each heartbeat cycle on the ECG.

However, in people who have LQTS, the QT interval usually lasts longer than normal. This can upset the careful timing of the heartbeat and trigger a dangerous, abnormal rhythm.

If you have inherited LQTS, you received the faulty gene(s) from one or both of your parents. Inherited LQTS is a lifelong condition.

Other names for Long QT Syndrome include the following:

  • Romano-Ward syndrome, affecting 1 in 5,000 people worldwide
  • Jervell and Lange-Nielsen syndrome affecting 1 in 6 million people worldwide, associated with deafness


NOTE: Jervell and Lange-Nielsen syndrome (J-LN) is the most severe variant of LQTS, with a very early onset and major QTc prolongation (the QT interval length corrected for changes in heart rate), and in which beta-blockers (drugs) have limited efficacy. Subgroups at a relatively lower risk for sudden cardiac arrest (CA/SD) are identifiable and include females, patients with a QTc  550 ms, those without events in the first year of life, and those with mutations on KCNE1. Early therapy with implanted cardioverter/ defibrillators must be considered.

 

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Causes and Risk Factors

What are the causes and risk factors of Long QT Syndrome?
LQTS is a rare condition that is usually inherited. It is often first detected in children and young adults. LQTS also may be acquired, rather than inherited, and caused by certain medicines and conditions.

  • About 1 in 5000-7,000 people has LQTS. But no one knows for sure because LQTS often goes undiagnosed.2
  • LQTS causes about 3,000 to 4,000 sudden deaths in children and young adults each year in the United States. Unexplained sudden death in children is rare. But when it does occur, LQTS often is the cause.2

Inherited LQTS and the Ion Channel
Inherited LQTS usually is first detected during childhood or young adulthood. Half of all people who have LQTS have their first abnormal heartbeat by the time they are 12 years old, and 90 percent by the time they are 40 years old. The condition rarely is diagnosed in someone after age 40.2

The heart relies on the ion channels to create the electrical activity in the heart muscle that makes the heart beat.

  • On the surface of each muscle cell in the heart are tiny pores called ion channels.
  • Ion channels open and close to let electrically charged sodium, calcium, and potassium atoms (ions) flow into and out of the cell.
  • The action of the ion channels generates the electrical activity used to make the heart beat.

Normally, the electrical activity of the heart spreads from one heart cell to the next in an orderly and coordinated way, like dominoes. In people who have LQTS, the ion channels may not work properly, or there may be too few of them. In this situation, the heart may suddenly develop a fast and abnormal heart rhythm that can be life threatening.

Many cases of LQTS are inherited, which means you're born with the condition and have it your whole life. There are seven known types of inherited LQTS. The most common ones are called LQTS 1, LQTS 2, and LQTS 3. Women who have LQTS are more likely to faint or die suddenly from the condition during menstruation and shortly after giving birth.2 In boys who have LQTS, the QT interval (on the ECG) often returns toward normal after puberty.2

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Risk Factors
Emotional stress or exercise (especially swimming) that makes the heart beat fast tends to trigger abnormal heart rhythms if you have LQTS 1. In LQTS 2, abnormal rhythms may be triggered by surprise or other extreme emotions. In LQTS 3, a slow heart rate during sleep may trigger an abnormal heart rhythm.

Major Risk Factors
You are at risk for having LQTS if:

  • Anyone in your family has ever had it. Unexplained fainting or seizures, drowning or near drowning, or unexplained sudden death are all possible signs of LQTS.
  • If you take medicines that make the QT interval longer. Your doctor can tell you whether prescription or over-the-counter medicines you take might do this.
  • if you have excessive vomiting or diarrhea or other conditions that cause low blood levels of potassium or sodium. These conditions include the eating disorders anorexia nervosa and bulimia and certain thyroid disorders.

Certain medicines or other medical conditions can cause acquired, or non-inherited, LQTS. Some of the commonly used medicines that may cause LQTS include:

  • Antihistamines and decongestants
  • Diuretics (pills that remove excess water from your body)
  • Antibiotics
  • Antidepressants
  • Cholesterol-lowering medicines and some diabetes medicines


The risk of developing an abnormal heartbeat that leads to fainting or sudden cardiac arrest may lessen with age, but the risk never disappears.

 

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Symptoms

What are the symptoms of Long QT Syndrome?
The signs and symptoms of LQTS-related arrhythmias include unexplained fainting or seizures after emotional stress or exercise (especially swimming),3 sudden cardiac arrest and sudden death. Signs and symptoms of LQTS-related arrhythmias often first appear during childhood.


Major Signs and Symptoms

  • Unexplained fainting. This happens because your heart isn't pumping enough blood to your brain. Fainting may occur when you're under physical or emotional stress. Some people will have fluttering feelings in their chests before they faint.
  • Unexplained seizures. Those around you may mistake your fainting from LQTS as a seizure due to epilepsy. In children, fainting may be seen as a hysterical reaction to a stressful situation.
  • Unexplained drowning or near drowning. This may be due to fainting while swimming.3
  • Unexplained sudden cardiac arrest (SCA) or death. This means that your heart suddenly stops beating for no obvious reason. People who have SCA will die within minutes unless they receive treatment. Most people who have SCA die. In about 1 out of 10 patients, SCA or sudden death is the first sign of LQTS.2

Often, people who have LQTS 3 will develop an abnormal heartbeat during sleep. This may cause them to have noisy gasping while sleeping.

 


 

Image of Patient Michael Garcia

“One morning I just woke up for school, hit my alarm clock to turn it off and suddenly felt dizzy. I tried to walk over the bed but I just blacked out.” - Michael Garcia, 14, Long QT Syndrome. Type 2. Florida



Long QT Syndrome without Symptoms
People who have LQTS may not have any signs or symptoms (silent LQTS). Doctors often advise family members of people who have the condition to be tested for it, even if they have no symptoms.


Medical and genetic tests may reveal whether they have LQTS and what type of the condition they have.

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Diagnosis

How is Long QT Syndrome diagnosed?
Cardiologists are doctors who specialize in the diagnosis and treatment of heart diseases, including long QT syndrome (LQTS). They will use an ECG and review your medical history. A genetic test may be recommended if LQTS is suspected in your family.

  • An ECG is a simple test that detects and records the heart's electrical activity. This test may reveal a long QT interval and other signs that make it more likely that you have LQTS. Often, doctors first discover a long QT interval when an ECG is done for another suspected heart problem.
  • Medical history and physical exam will tell your doctor about any symptoms of an abnormal heartbeat, including unexplained fainting, a fluttering in your chest, or loud gasping during sleep.
  • Genetic blood tests can detect some forms of inherited LQTS. If your doctor suspects that you have LQTS, he or she may recommend genetic testing. Genetic blood tests usually are suggested for family members of people who have LQTS as well. However, genetic tests can't detect about one-third of LQTS cases. So, even if you have LQTS, the tests may not show it.

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Treatment

How is Long QT Syndrome treated?
The goal of treating long QT syndrome (LQTS) is to prevent life-threatening, abnormal heartbeats and fainting spells. Treatment isn't a cure for this condition and may not restore a normal QT interval on an ECG. But treatment does greatly improve survival.

People at higher risk are those who have fainted or who have developed dangerous heart rhythms from their LQTS in the past.

Common treatment options for people with LQTS include the following:

  • Make lifestyle changes that reduce the risk of fainting or SCA. These may include avoiding competitive sports and strenuous exercise, such as swimming, which can cause abnormal heartbeats.
  • Avoid medicines that may trigger symptoms. This may include some medicines used to treat allergies, infections, high blood pressure, high blood cholesterol, and depression. The type of LQTS you have will determine which medicines you take to avoid abnormal heart rhythms. For example, doctors usually only will prescribe sodium channel blocker medicines for people who have LQTS 3.
  • Take medicines, such as beta-blockers, which reduce the risk of symptoms by slowing your heart rate.

If your doctor thinks you are at higher risk for LQTS complications, he or she may suggest a variety of treatments, including medicines and lifestyle changes. Other treatments include:




Image of Patient Lizzie Garcia

The morning of Halloween 2007, I woke up to go put on my costume to get ready for school and I got really dizzy and I blacked out. But before I even came back, my ICD had gone off. It saved me." Lizzie Garcia

 


 

If you have questions about symptoms and suspect long QT syndrome, consult a healthcare provider.

 

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Success Stories

Image of Patient's Lizzie and Michael Garcia

What is it like to have Long QT Syndrome?
Long QT syndrome (LQTS) usually runs in families, like the Garcia’s.

"The morning of Halloween 2007, I woke up to go put on my costume to get ready for school and I got really dizzy and I blacked out. But before I even came back, my ICD had gone off. It saved me." Lizzie Garcia, ICD at age 16. Long QT syndrome, Type 2, Florida. Hear their story >>


Learn More

Cardiac Arrhythmia Research and Education (CARE) Foundation
Sudden Arrhythmia Death Syndrome (SADS)
FAMILION® Genetic Tests

Next:Sudden Cardiac Arrest >>

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Note: Individual symptoms, situations, and circumstances may vary. Please consult your physician or qualified healthcare provider regarding your condition and appropriate medical treatment. The information provided is not intended to be used for medical diagnosis or treatment, or as a substitute for professional medical advice.

1. AHA. Jervell and Lange-Nielsen Syndrome. Circulation. 2006;113:783-790.
2. National Heart Lung and Blood Institute. http://www.nhlbi.nih.gov/health/dci/Diseases/qt/qt_all.html Accessed 110109.
3. Ackerman MJ, et al. Swimming, a gene-specific arrhythmogenic trigger for inherited long QT syndrome. Mayo Clin Proc. Nov 1999;74(11):1088-1094.


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