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Learning About Long QT Syndrome (LQTS)

Cross section of the heart, showing the electrical system

What is long QT syndrome (LQTS)?

Long QT syndrome (LQTS) is a rare problem that affects the heart's electrical system. It may cause the heart to beat in a fast and abnormal way. This can cause fainting, seizures, or abnormal heartbeats that can become life-threatening. If the heart stops pumping blood, sudden death can happen.

What causes it?

A person can be born with LQTS. The gene for it can be passed down in families. So if one family member has it, other members of the family are more likely to have it too.

Or something else can cause it. It could be a reaction to a medicine. It may be caused by a condition that causes vomiting or diarrhea. A severe lack of nutrition also can cause it. These problems can cause a mineral imbalance in the blood that can affect how the heart works.

What are the symptoms?

Some people don't have symptoms. But in those who do, symptoms include fainting, seizures, and feeling dizzy or light-headed. Heart palpitations also can occur. LQTS can also cause sudden cardiac arrest. This means that the heart suddenly stops beating. In some people, symptoms may be triggered by exercise, stress, or being startled.

How is it diagnosed?

Your doctor will do a physical exam and ask questions about your symptoms. The doctor will also ask about your past health and your family history.

Most people are diagnosed using an electrocardiogram (ECG or EKG). It shows your heart's electrical activity as line tracings on paper. People with the syndrome have a certain pattern to their heartbeat. Your doctor can see the pattern on the tracing. Some people are brought to the hospital for a special ECG done during a medication infusion.

Your doctor may want to do other tests too. You might get a test to measure your heartbeat during exercise. Or the doctor may ask you to wear a small device at home. It measures your heartbeat during regular activity outside of the doctor's office.

A test may also be done to see if you carry the changed gene that causes LQTS. Your close relatives may also get tests. Not everyone who has the gene will have symptoms.

How is it treated?

The goals of treatment are to prevent life-threatening heart rhythms and to control symptoms. Treatment depends on your symptoms and on what type of LQTS you have.

For instance, if you got LQTS later in life, treatments include stopping any medicines that can cause the problem and fixing any mineral imbalances you have. If that doesn't work, or if you were born with LQTS, you may have other treatments. They include:

  • Medicines to control your heartbeat. These are called beta-blockers.
  • A device called a pacemaker. It's implanted under the skin of your chest. It helps control your heartbeat.
  • A device called an implantable cardioverter-defibrillator. It's implanted in your chest. It uses a shock to stop a dangerous heart rhythm.
  • Surgery to remove nerves that make abnormal heartbeats more likely.

How can you care for yourself?

There are things you can do to help prevent a dangerous heart rhythm from LQTS.

  • Tell all of your doctors and your pharmacist about your condition.

    They can help you avoid medicines that can start a fast or abnormal heartbeat.

  • Ask your doctor for a list of over-the-counter medicines that you shouldn't take.

    These include some common medicines, such as certain antacids and antihistamines. They can trigger abnormal heartbeats in people with LQTS.

  • Talk to your doctor about whether lifestyle changes are a good idea for you.

    Some people with LQTS may need to avoid loud noises, such as alarm clocks and loud ringtones.

  • Ask your doctor about safe levels of activity.

    Most people with LQTS should avoid intense physical activity. Talk to your doctor about what type of activity and exercise is safe for you.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Where can you learn more?

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