Long QT Syndrome :A syndrome that results in fast erratic heartbeats


Fast, erratic heartbeats may result from the cardiac signaling condition known as long QT syndrome (LQTS) (arrhythmias). Heart signal problems are sometimes referred to as cardiac conduction disorders.

Some individuals are born with long QT syndrome due to changed DNA (congenital long QT syndrome). As a result of various medical problems, specific medications, or mineral imbalances, long QT syndrome can also develop later in life (acquired long QT syndrome).

Sudden death is more likely in young persons with LQTS syndrome.

Lifestyle modifications and drugs to stop hazardous heartbeats are part of the treatment for long QT syndrome. The implantation of a device to regulate the heart's rhythm occasionally requires surgery.


A cardiac rhythm issue called long QT syndrome is brought on by modifications to the heart's electrical recharging mechanism. The physical makeup of the heart is unaffected.

Every time the heart beats, a normal heart pumps blood to the body. The heart's chambers constrict (contract) to pump blood and then relax. The cardiovascular system's electrical system is in charge of this synchronized activity. The heart's electrical signals, or impulses, go from the top to the bottom. They instruct the heart to beat and contract. The mechanism refuels after each heartbeat to get ready for the following one.

The heart's electrical system recharges between beats more slowly than usual in long QT syndrome. This delay is known as a prolonged QT interval.  An electrocardiogram could reveal it (ECG).

 Depending on the underlying reason, there are often two basic classifications for QT syndrome.

It is referred to as congenital long QT syndrome if you are born with the disorder. Certain types of long QT syndrome are brought on by changed DNA that is inherited from parents to children (inherited).

It is referred to as acquired long QT syndrome if an underlying medical condition or drug is the root cause. When the underlying cause is found and addressed, this kind of long QT syndrome is typically curable.

Long QT syndrome has so far been connected to more than a dozen genes. Many changes have been found in these genes, according to researchers.

Congenital long QT syndrome can have one of two forms:

  • a Romano-Ward condition (autosomal dominant form). This most prevalent kind affects people who only have one gene variation from a single parent.
  • Syndromes Jervell and Lange-Nielsen (autosomal recessive form). The more severe episodes of this unusual variant of LQTS typically start very early in life. Children with this condition inherit distorted gene variations from both parents. The infants are born deaf and with long QT syndrome.

More than 100 drugs, many of which are widely used, can lengthen QT intervals in otherwise healthy individuals.

Drug-induced long QT syndrome is the term used if a medicine results in acquired long QT syndrome (LQTS). The following medications can result in LQTS:

  • Azithromycin (Zithromax)
  • Erythromycin (Eryc, Erythrocin, and others), and other antibiotics
  • Specific antifungal medications for treating yeast infections
  • Those diuretics bring about an electrolyte imbalance (low potassium, most commonly)
  • Antiarrhythmic medications for the heart that prolong the QT interval
  • Many antipsychotic and antidepressant medicines
  • A number of nausea drugs

Always be honest with your doctor about all of the drugs you use, even those you get over the counter.

The following medical disorders can result in acquired long QT syndrome:

  • Hypothermia is defined as a body temperature below 37 degrees Celsius (95 degrees Fahrenheit).
  • Poor calcium (hypocalcemia)
  • Reduced magnesium (hypomagnesemia)
  • Reduced potassium (hypokalemia)
  • Adrenal gland tumour that is not malignant (pheochromocytoma)
  • Brain or stroke (intracranial) bleed
  • Thyroid dysfunction (hypothyroidism)

How to check if you have Long QT Syndrome?

If you have unexpected dizziness with physical exertion, emotional arousal, or after taking any new medicine, contact your healthcare professional right once. Tell your provider if you have a parent, sibling, or kid who has long QT syndrome. A family may carry the long QT syndrome.

Risk Factors

The following items may raise the likelihood of acquiring long QT syndrome:

  • A history of cardiac arrest
  • Having a parent, sibling or kid with long QT syndrome
  • Taking drugs known to produce extended QT intervals
  • Being feminine and on cardiac medication
  • Severe vomiting or diarrhoea, which causes electrolyte imbalances
  • Eating disorders that result in electrolyte imbalances, including anorexia nervosa

Inform your healthcare practitioner if you have long QT syndrome and are thinking about getting pregnant. Throughout your pregnancy, your doctor will want to closely watch you in order to assist you to avoid situations that can cause an LQTS episode.


Long QT syndrome (LQTS) might cause some persons to have no symptoms at all. When an electrocardiogram (ECG) or genetic testing is performed for another purpose, the problem may be found.

Long QT syndrome can cause fainting spells to happen suddenly or with little to no notice. Some people have the following initial fainting warning signs:

  • Distorted vision
  • Lightheadedness
  • Rapid heartbeats (palpitations)
  • Weakness

When the heart briefly beats erratically, it causes fainting. When you are nervous, furious, afraid, or exercising, you might pass out. You could pass out if something catches you off guard, such as an alarm clock or a phone.

Some persons who have long QT syndrome may also experience seizures. This can occasionally happen while you sleep.

Most LQTS sufferers experience their first episode around the age of 40. Congenital long QT syndrome is a disorder in which symptoms can appear as early as the first few weeks to months of life or even later in childhood.

After a protracted QT episode, the heart usually settles back into its regular beat. Sudden death will occur if the heart does not correct its own rhythm or if an external defibrillator is not utilized in time to do so.


Health issues that might cause some kinds of acquired long QT syndrome may be avoided with routine checkups and open contact with your doctor. Avoiding drugs that might alter heart rhythm and lengthen the QT interval is especially crucial.

Congenital long QT syndrome is not yet treatable. Families with an inherited form of the disorder may want to pursue genetic testing. You can control and stop the risky heartbeats that might cause consequences from long QT syndrome with the right medical care.


Long QT syndrome (LQTS) can be treated with medication, lifestyle modifications, surgery, or other treatments.

Treatment for LQTS aims to stop irregular heartbeats and abrupt death. Based on your symptoms and the type of long QT syndrome, your doctor will talk with you about the best course of action. Even if you do not have symptoms very often, you can still require therapy.

If you have drug-induced long QT syndrome, treating the problem may only require quitting the offending medication. You can learn how to do this securely from your healthcare practitioner.

Treating the underlying illness is required for treating other varieties of acquired long QT syndrome. Treatment options vary but may involve intravenous magnesium or other fluids to balance out electrolyte problems.


Long QT syndrome cannot be cured by medication, but it can help prevent potentially fatal cardiac rhythm alterations.

The following medicines may be used to treat long QT syndrome:

Beta-blockers. Most patients with long QT syndrome receive this type of cardiac medication as routine care. They reduce the likelihood of long QT events and slow down the heart rate. Beta-blockers such as nadolol (Corgard) and propranolol are used to treat long QT syndrome (Inderal LA, InnoPran XL).

Mexiletine. Using this beta blocker with this cardiac rhythm medication may help decrease the QT interval and lower the risk of fainting, seizures, or sudden death. Use prescription drugs just as prescribed.

Treatments such as surgery

For certain sufferers of long QT syndrome, heartbeat control surgery is required. treatments such as surgery used to treat LQTS may include:

Surgery for left cardiac sympathetic denervation (LCSD). Only those with long QT syndrome and ongoing cardiac rhythm issues who cannot take or tolerate beta blockers are often advised to undergo LCSD surgery. Although it does not treat long QT syndrome, it does assist in lowering the danger of unexpected death. Certain nerves along the left side of the chest's spine are removed by doctors during this treatment. The sympathetic nervous system of the body, which aids in regulating heart rhythm, is made up of these nerves.

Cardioverter-defibrillator implant (ICD). Similar to a pacemaker, an ICD is a battery-operated device that is implanted under the skin close to the collarbone. The ICD continually monitors the cardiac rhythm. The gadget emits shocks if it detects an irregular heartbeat. 

ICDs are not often required in long QT syndrome patients. To enable a comeback to competitive sports, an ICD may be advised for some athletes. It is important to think carefully before implanting an ICD, especially in youngsters. ICD implantation is a significant surgery that might lead to improper shocks and other consequences.

Complications of Long QT Syndrome

Lifestyle modifications and appropriate medical care can help reduce long QT syndrome-related problems.

The following are potential long QT syndrome side effects:

Pointed torsions ("twisting of the points"). There is a potentially fatal irregular heartbeat here (arrhythmia). The waves on an ECG monitor seem twisted because of the rapid and erratic beating of the two lower chambers of the heart (ventricles). Less blood is pumped out by the heart. Sudden fainting, frequently without notice, is brought on by a shortage of blood to the brain.

A full-body seizure may come after fainting if the incident lasts a long period. Ventricular fibrillation, a life-threatening arrhythmia, develops if the risky rhythm does not correct itself.

Fibrillation in the ventricles. Due to this ailment, the lower heart chambers pulse so quickly that the heart stops beating. Ventricular fibrillation can result in brain damage and rapid death if a defibrillator is not used to restore the heart's rhythm.

Unexpected death. The unexpected death of young persons who otherwise look healthy has been related to long QT syndrome. Certain inexplicable incidents in children and young people, such as unexplained fainting, drownings, or seizures, might be caused by the syndrome.


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Page last reviewed: Mar 17, 2023

Next review due: Mar 17, 2025

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