Patient education: Long QT syndrome (The Basics)

What is long QT syndrome? — Long QT syndrome is a condition that affects the heart's electrical system. It sometimes leads to serious heart rhythm problems that can be life-threatening.

There are 2 main types of long QT syndrome:

●A type that people are born with – This is caused by a specific change in a gene.

●A type that happens later in life – People are not born with this type. Certain medicines can cause long QT syndrome. Mineral imbalances in the body, such as having too little potassium or magnesium, can also cause long QT syndrome.

What are the symptoms of long QT syndrome? — Many people with long QT syndrome have no symptoms. They find out they have it after they have a test called an electrocardiogram (also called an "ECG") done for another reason. An ECG measures the electrical activity in the heart (figure 1).

When long QT syndrome causes symptoms, they can include:

●Heartbeat changes called "palpitations" – These can feel like your heart is beating hard or fast, or skipping beats.

●Fainting, or feeling like you are going to faint

●Seizures – Seizures are waves of abnormal electrical activity in the brain that can make people pass out or move or behave strangely.

●Sudden cardiac arrest – This is when the heart suddenly stops beating. It is a medical emergency that needs to be treated right away.

Is there a test for long QT syndrome? — Yes. An ECG usually shows whether someone has long QT syndrome. But some people will have other tests, too. These can include:

●Longer-term heart monitoring – There are several devices that can be used for this. A "Holter" monitor (figure 2) is a small, portable machine you wear that records all your heart's electrical activity over 1 or 2 days. There are also newer types of monitors called "patch" monitors. These go directly on the skin, without wires, and can be worn for up to 14 days. You wear these monitors all the time while you do your usual activities.

●A stress test – During this test, a doctor, nurse, or physician assistant records your ECG while you exercise on a treadmill or bike, or while you get medicine to make your heart pump faster (figure 3).

●Tests to see how your heartbeat changes when you get certain medicines

●Blood tests – These include tests to check mineral levels and to look for specific changes in the gene that causes long QT syndrome.

How is long QT syndrome treated? — Treatment depends mostly on whether you were born with long QT syndrome or developed it later in life.

For people who were born with long QT syndrome, the main treatment includes medicines called beta blockers. These medicines help keep the heart from beating too fast. Some people need other treatments, too. These can include:

●Other types of heart medicines

●A pacemaker – This is a device that goes under the skin near a person's heart (figure 4). It sends electrical signals to the heart to control the heartbeat.

●An implantable cardioverter-defibrillator (called an "ICD") – This is a device that goes under a person's skin near their heart (figure 5). It can sense abnormal heartbeats and then treat them with an electrical shock.

For people who develop long QT syndrome later in life, treatment can include:

●Stopping any medicine that could be causing the long QT syndrome

●Fixing the mineral imbalance that is causing the long QT syndrome

●A pacemaker (figure 4)

●Medicines that control the speed or rhythm of the heartbeat

All people with long QT syndrome who have a sudden cardiac arrest should be treated with defibrillation. This involves using a device to send an electrical shock to the heart. It sometimes works to get a normal heart rhythm started again.

What else should I do? — If you have long QT syndrome, you should:

●Follow all of your doctor's instructions about follow-up tests, so they can monitor your condition

●Avoid taking medicines that are likely to cause long QT syndrome. Your doctor can give you a list of these medicines or refer you to a website that has updated lists of medicines.

●Let your family members know. Because long QT syndrome can run in families, they might need to be tested for the condition, too.

●Ask your doctor or nurse whether you need to make any lifestyle changes. With some types of long QT syndrome that people are born with, abnormal heart rhythms are triggered by certain things. These might include intense exercise, loud or sudden noises, or diving into cold water. If you have this type of long QT syndrome, you will need to avoid these triggers as much as possible.

More on this topic

Patient education: Syncope (fainting) (The Basics)
Patient education: Sudden cardiac arrest (The Basics)
Patient education: ECG and stress test (The Basics)
Patient education: Pacemakers (The Basics)
Patient education: Implantable cardioverter-defibrillators (The Basics)
Patient education: Ventricular tachycardia (The Basics)
Patient education: CPR for adults (The Basics)
Patient education: CPR for children (The Basics)

Patient education: Syncope (fainting) (Beyond the Basics)
Patient education: Pacemakers (Beyond the Basics)
Patient education: Implantable cardioverter-defibrillators (Beyond the Basics)
Patient education: Cardioversion (Beyond the Basics)