Long QT syndrome 


Long QT syndrome (LQTS) affects the bottom chambers of the heart, causing a rapid heart rate and abnormal rhythm

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About Long QT syndrome

Long QT syndrome is usually inherited but it can be caused by certain medications. It affects the bottom pumping chambers of the heart (ventricles), and can cause a fast and dangerous heart rhythm that can lead to fainting or even cardiac arrest.

Need to know 

Some people with LQTS have no symptoms and the condition is only detected on a heart monitor or during an electrocardiogram (ECG) carried out for other reasons. Some symptoms include:

These symptoms can be triggered by strenuous exercise, stress, a sudden noise or a slow heart rate while sleeping.

An electrocardiogram (ECG) is the main way to detect long QT syndrome. If you have this condition, it shows up on an ECG as a lengthened QT interval, which is part of the heartbeat cycle.

  • Sometimes other tests are needed such as an exercise ECG, which is an ECG carried out during physical exertion. Alternatively, you may be given a Holter monitor, which is a portable ECG recording device to wear for up to a few days to get more readings. Genetic testing can also be carried out and may help determine your type of LQTS.
Treatment can help prevent the symptoms of LQTS and minimise the risk of fainting or cardiac arrest. Inherited LQTS is usually treated with medicines. Depending on your symptoms, you may also need to have an implantable cardioverter defribillator device fitted. This is implanted under the skin on your chest and wires connect it to your heart. It monitors your heart rhythm and can give a brief electrical shock to reset the rhythm. People with non-inherited LQTS are usually treated by changing the medicines that caused the problem.

Our locations

The Harley Street Clinic

The Harley Street Clinic

35 Weymouth Street W1G 8BJ London
The Lister Hospital

The Lister Hospital

Chelsea Bridge Road, SW1W 8RH London
The Cardiac Clinic

The Cardiac Clinic

London Bridge Hospital SE1 2PR London

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This content is intended for general information only and does not replace the need for personal advice from a qualified health professional.