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Long QT Syndrome

Long QT Syndrome: Symptoms, Cause and Risk Factors, Diagnosis, Treatment | National Heart Centre Singapore

Long QT Syndrome - What it is

​Long QT syndrome (LQTS) is a rare congenital and inherited or acquired heart condition in which electrical abnormality of the heart increases the risk of episodes of torsades de pointes (TdP, a form of irregular heartbeat that originates from the ventricles). These episodes may lead to fainting and sudden death due to ventricular fibrillation. Episodes may be provoked by various stimuli, depending on the subtype of the condition.

How did the condition get its name?

The QT interval on an ECG indicates the time the heart takes to recharge before beginning its next contraction. In LQTS, the QT interval is prolonged as the electrical system controlling the heart’s rhythms takes longer to recharge. The delay may result in dangerous heart rhythms.

What happens during an attack?

Victims develop sudden, uncontrollable and chaotic heart rhythms during a triggered situation.  It is a known cause of collapse and sudden death in young athletes running marathons. If not corrected within a couple of minutes, these erratic heart rhythms can cause death.

Long QT Syndrome - Symptoms

As LQTS has no signs or symptoms, many people are unaware they have it. See a doctor if:
  • A parent, sibling or child has been diagnosed with LQTS. The condition may be inherited.
  • You suddenly faint during physical exertion or when you experience intense emotions.
  • You have seizures. A continually erratic heartbeat deprives the brain of oxygen – this condition is what causes seizures.

Long QT Syndrome - How to prevent?

​Any causative drugs should be avoided.

Long QT Syndrome - Causes and Risk Factors

​LQTS is usually inherited and can affect young victims. Patients can be born with a genetic mutation which puts them at a higher risk of developing long QT syndrome. Certain types of medical conditions and medications might also cause long QT syndrome.

Long QT Syndrome - Diagnosis

Diagnosis typically starts with a physical examination by a doctor, assessing your medical history and conducting routine tests. Other tests recommended may include:

Long QT Syndrome - Treatments

Studies have shown that if left untreated, more than 50 per cent of people with inherited Long QT Syndrome (LQTS) die within 10 years.

To manage LQTS, patients are advised to avoid competitive sports. Treatment includes the following:

Medication: Drugs like beta-blockers slow the heart rate by blunting the heart’s reaction to adrenaline in times of stress, fear or exertion, making dangerous rhythms in a patient with LQTS less likely.

Medical procedures: The only way to prevent deaths in LQTS patients is to get an automated implantable cardioverter defibrillator implanted in their bodies.

The device is implanted under the skin of the patient’s chest, where it continuously monitors his heartbeat. It will deliver electrical shocks to restore a normal heart rhythm when necessary. However, this does not cure or correct the underlying cause of the condition.

Long QT Syndrome - Preparing for surgery

Long QT Syndrome - Post-surgery care

Long QT Syndrome - Other Information

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