ABC Medical Center > Long QT syndrome

What is Long QT syndrome?

18:27 - 5 December , 2023


It is a cardiac pathology in which the heart beats rapidly and the rhythm is altered, which can cause sudden fainting or seizures and sudden death in young people.

Long QT syndrome, also known as heart conduction disorder, appears due to changes in the heart’s electrical system.

There are a series of conditions that can contribute to its appearance, such as:

  • Family members with this condition.
  • Electrolyte imbalances due to diarrhea and/or vomiting.
  • History of cardiac arrest.
  • Drugs that produce extended QT intervals.
  • Heart medications.
  • Medical conditions, such as low levels of calcium, magnesium, and potassium; stroke or bleeding in the brain, and hypothyroidism, among others.
  • Eating disorders that cause electrolyte imbalances.

People who suffer from long QT syndrome usually develop symptoms before turning 40. If the disorder is congenital, symptoms may arise during the first weeks or months of life.

Long QT syndrome is classified, depending on the cause, into:

  • Congenital long QT syndrome: changes in DNA transmitted from parents to children. There are two types:
    • Romano-Ward syndrome, common in people who inherit a single genetic variant from one parent.
    • Jervell and Lange-Nielsen syndrome, in which children receive altered genetic variants from both parents.
  • Acquired long QT syndrome: occurs as a result of a pre-existing disease or the intake of some medication.

Signs and symptoms Long QT syndrome

  • Daze.
  • Weakness.
  • Palpitations.
  • Blurred vision.
  • Fainting.
  • Seizures.

The greatest risk of long QT syndrome is ventricular fibrillation, as well as sudden death.

Diagnosis and treatment Long QT syndrome

Once the doctor analyzes your symptoms and clinical history, they will perform a physical examination and request a series of tests to rule out other conditions and make an accurate diagnosis, including:

  • Holter monitor.
  • Stress test.
  • Genetic testing.

Treatment consists of taking medications that help prevent irregular heartbeats and changes in lifestyle.

Implantation of a device to control heart rhythm may be required in more severe cases.

At the Cardiovascular Center, we offer you a wide range of prevention, diagnosis, timely treatment, and follow-up services to care for you through a comprehensive and multidisciplinary care model. Come to us, we want to hear your heart.


  • texasheart.com
  • nhlbi.nih.gov
  • revespcardiol.org
  • secardiologia.es
  • mayoclinic.org
  • medlineplus.gov
  • msdmanuals.com
  • medigraphic.org
  • Estévez RY, Domínguez SR, Padilla BTD, et al. Síndrome de QT largo en la embarazada con el uso de la oxitocina. CorSalud. 2021;13(2):195-199.
  • Fernández DD, Cruz BR, Cabrera PAJ, et al. Factores de riesgo asociados a síndrome QT largo en anestesia cardiovascular. Revista Cubana de Anestesiología y Reanimación. 2017;16(3):1-16.
  • Gallardo MY, Puga BMV, Román RPA, et al. Síndrome de QT largo y embarazo. Experiencia en Cuba. Rev Cubana Cardiol Cir Cardiovasc. 2018;24(2):.

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