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Bradycardia Causes and Symptoms

Bradycardia (Slow Heart Rate)

The causes of a slow heart rate may include underactive thyroid (hypothyroidism), an electrolyte imbalance, or medicines you may be taking for certain conditions. The treatment for Bradycardia depends on what is causing it, and your doctor will evaluate your current health status and medical history to determine the correct course of treatment.


Common bradycardia causes include:

  • A hereditary heart defect
  • Certain illnesses or heart medications
  • The natural aging process
  • Scar tissue from a heart attack
  • Sick sinus syndrome (eg, sinus bradycardia or sinus node dysfunction)
  • The heart's natural pacemaker is not functioning correctly
  • Heart block
  • The electrical impulse that travels from the upper to the lower chamber of the heart is irregular or blocked

Bradycardia Symptoms

When your heart beats too slowly, it is not supplying the body with sufficient oxygen. Your doctor will assess and diagnosis your heart condition, but slow heart rate symptoms may include:

  • Dizziness and fainting
  • Chronic lack of energy
  • Shortness of breath
  • Fainting

Risk Factors

Your risk of developing an abnormally slow heartbeat (bradycardia) is greater if you:

  • Have certain types of heart disease
  • Are taking certain medicines
  • Are age 65 or older
  • Have recently had heart surgery

Learn more about bradycardia diagnosis and treatment.

Information on this site should not be used as a substitute for talking with your doctor. Always talk with your doctor about diagnosis and treatment information.