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• Back to Diseases and Conditions
• Arrhythmias
• Atrial Fibrillation
• Bradycardia or Low Heart Rate
• Brugada Syndrome
• Long QT Syndrome
  • Signs and Symptoms
  • Risk Factors
  • Causes
  • Diagnosis
  • Treatments
  • Physicians and Services
• Palpitations
• Sudden Death or Cardiac Arrest
• Syncope or Fainting
• Tachycardia or Fast Heart Rate
• Wolff-Parkinson-White Syndrome

Causes

Genetic Abnormality

In most cases, a genetic abnormality is to blame for long QT syndrome. Faulty genes that control the production of certain types of ion channels in your heart cells cause the condition. Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of all living cells.

At least 12 Genes Are Associated with Long QT Syndrome

At least 12 genes have been identified so far that are associated with long QT syndrome. These genes may cause the body to produce too few ion channels or ion channels that don't work as they should, or both. There are seven known types of inherited LQTS (types 1 though 7). Some LQTS types result from faulty potassium ion channels, while others are due to faulty sodium channels.

Medications

At least 50 medications are known to cause LQTS. Among them are:

• Antihistamines
  
• Decongestants
  
• Diuretics
  
• Antibiotics
  
• Antidepressants
  
• Cholesterol drugs
  
• Some diabetes medications