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What Are the Signs and Symptoms of Heart Block?

Signs and symptoms depend on the type of heart block you have. First-degree heart block may not cause any symptoms.

Signs and symptoms of second- and third-degree heart block include:

  • Fainting
  • Dizziness or light-headedness
  • Fatigue (tiredness)
  • Shortness of breath
  • Chest pain

These symptoms may suggest other health problems as well. If these symptoms are new or severe, call 9–1–1 or have someone drive you to the hospital emergency room. If you have milder symptoms, talk with your doctor right away to find out whether you need prompt treatment.

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Heart Block Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Heart Block, visit

Know the Facts and Act Fast!

Collage image of new heart attack materials

When a heart attack happens, any delays in treatment can be deadly. 

Knowing the warning symptoms of a heart attack and how to take action can save your life or someone else’s.

The NHLBI has created a new series of informative, easy-to-read heart attack materials to help the public better understand the facts about heart attacks and how to act fast to save a life.

Click the links to download or order the NHLBI's new heart attack materials:

“Don’t Take a Chance With a Heart Attack: Know the Facts and Act Fast” (also available in Spanish)

“Heart Attack: Know the Symptoms. Take Action.”

“Learn What a Heart Attack Feels Like—It Could Save Your Life”

July 09, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.