Long Q-T syndrome is a disorder of the heart’s electrical system. It is often inherited and present from birth. It can also be caused by certain medications.

What is Long Q-T syndrome?

Long Q-T syndrome (LQTS) is a disorder of the heart’s electrical system. It is often inherited and present from birth. It can also be caused by certain medications.

What are the symptoms of Long Q-T syndrome?

Some people with LQTS often have no symptoms. If there are symptoms, they may include:

  • Fainting
  • Dizziness
  • Seizures
  • Abnormal rate and rhythm of the heartbeat (arrhythmia)

If not detected and treated, LQTS can lead to sudden death.

Learn more about the symptoms of LQTS.

What are the causes of Long Q-T syndrome?

LQTS is often inherited. This means you get LQTS from your parents and grandparents because you share their genes.

Certain medications may also cause LQTS, such as antihistamines and decongestants, diuretics (pills that remove excess water from your body), antibiotics, antiarrhythmic medicines, antidepressant and antipsychotic medicines, cholesterol-lowering medicines and some diabetes medicines.

Learn more about the causes of Long Q-T syndrome.

How is Long Q-T syndrome diagnosed?

Your doctor will review your medical history and order an electrocardiogram (ECG) or transesophageal echocardiogram (TEE). LQTS can be hard to diagnose because some patients do not have a visibly prolonged QT interval on an electrocardiogram test.

Speak to your family doctor about seeing a cardiologist who specializes in cardiac rhythm disorders for further testing. Additional tests may include stress test (exercise tolerance test or ETT) and genetic testing.

What treatment is available for Long Q-T syndrome?

Your doctor may treat your condition with a combination of medication and lifestyle changes.

Beta-blockers are the most commonly prescribed medication to slow your heart rate by reducing the effect of adrenaline on your heart.

Surgery options for LQTS include left cardiac sympathetic denervation surgery and implantable cardioverter-defibrillator (ICD).

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