Heart Block

Heart block is a problem with your heartbeat signal moving from the upper to lower part of your heart. The signal can only get through sometimes, or not at all. This makes your heart beat slowly or skip beats. People with second-degree or third-degree heart block may experience fainting, tiredness and shortness of breath.


With heart block, heartbeat signals meant for your ventricles may be slow, unreliable or fully blocked.
Heart block keeps heartbeat signals from reaching your heart’s lower chambers on time, every time or at all.

What is heart block?

Heart block is an issue with a heartbeat signal traveling from the top chambers of your heart to the bottom chambers of your heart. Normally, electrical signals (impulses) travel from your heart’s upper chambers (atria) to your lower chambers (ventricles). The signal moves through your AV node, a cluster of cells that link the electrical activity from your top to bottom chambers. If you have heart block, the signal only makes it to your ventricles some of the time, if at all.

The result is a heart that may not work well. Your heart may beat slowly or skip beats. In severe cases, heart block can affect your heart’s ability to pump blood, causing low blood flow to your entire body.

People are more likely to acquire heart block later in life than to have it at birth.

Other names for heart block are atrioventricular (AV) block or a conduction disorder.

Types of heart block

Heart blocks can range from mild to severe, depending on whether the electrical signal can get through, and how often. Heart block types are:

First-degree heart block: The electrical impulse still reaches your ventricles, but moves more slowly than normal through the AV node. This is the most mild type of heart block.

Second-degree (incomplete) heart block: With this type, your heart’s impulses only get to the lower chambers some of the time. The types of second-degree heart block are:

  • Type I, also called Mobitz Type I or Wenckebach’s AV block: This is a less serious form of second-degree heart block. The electrical signal gets slower and slower until your heart actually skips a beat.
  • Type II, also called Mobitz Type II: While most of the electrical signals reach your ventricles, every so often, some don’t. Your heartbeat becomes irregular and slower than normal. This form of second-degree heart block is more serious and may warrant a pacemaker.

Third-degree heart block: This is a complete blockage of the electrical signal from your atria to your ventricles. Third-degree block negatively affects your heart’s ability to pump blood out to your body. This form of heart block is serious and usually requires a pacemaker for treatment.


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Symptoms and Causes

What are the symptoms?

Symptoms of heart block vary depending on the severity of the block and how it affects the heart pump.

Heart block symptoms may include:

People with first-degree heart block may not have any symptoms. A provider may find first-degree heart block during a routine electrocardiogram (EKG).

Symptoms of third-degree heart block are more intense due to the slow heart rate. If you have severe symptoms, get medical attention right away.

What causes heart block?

Causes of heart block include:

What are the risk factors for heart block?

You may be at an increased risk of a heart block if:

  • You have other heart conditions like coronary artery disease or heart valve disease.
  • You’ve had abnormalities in your heart since birth.
  • You have a disease (like rheumatic heart disease or sarcoidosis) that affects your heart.
  • You have an overactive vagus nerve that causes your heart to slow down.
  • You take medications that make your heart’s electrical impulses move more slowly. These drugs may include heart and blood pressure medications (beta-blockers, diuretics, calcium channel blockers, digoxin), antiarrhythmics, muscle relaxants, sedatives, antidepressants and antipsychotics.


What are the complications of heart block?

The complications can be life-threatening and include:

Diagnosis and Tests

How is heart block diagnosed?

To diagnose heart block, your healthcare provider will:

  • Review your medical history.
  • Review your biological family’s health history.
  • Ask questions about your overall health, eating habits, physical activity level and symptoms.
  • Ask you about any medications you’re taking (prescription or over the counter).
  • Ask you if you smoke or use recreational drugs.
  • Listen to your heart and check your heart rate.
  • Check for signs of heart failure, like fluid buildup in your feet, ankles and legs.

Your cardiologist may refer you to an electrophysiologist, an expert in the electrical activity of your heart.

What tests will be done to diagnose heart block?

Tests you might have include:


Management and Treatment

How is heart block treated?

Heart block treatment varies from person to person. A provider may admit you to the hospital to monitor your heart. To manage your condition, your cardiologist will consider:

  • Which type of heart block you have.
  • The severity of your heart block.
  • How it affects your heart’s ability to function.
  • The symptoms you’re having.

Sometimes, making changes to medicines or treatment for heart disease stops heart block. Other people may need a temporary or permanent pacemaker that sends electrical pulses to their hearts.

  • First-degree block: You probably won’t need treatment.
  • Second-degree block: You may not need treatment if you have Type 1. If you have symptoms, you may need a temporary or permanent pacemaker to keep your heart beating like it should.
  • Third-degree block: People with this type almost always need a pacemaker.

If you need a pacemaker, your provider will talk to you about the details, the type that’s best for you, and what to expect before, during and after you get your pacemaker.

Complications/side effects of the treatment

If you receive a temporary or permanent pacemaker, you may have side effects like:

  • Issues with the device’s programming.
  • Device malfunctions.
  • Infection.
  • Blood clots.
  • Injury to your heart.

How long does it take to recover from this treatment?

After receiving a pacemaker, you may need to stay overnight in the hospital. You should be able to get back to your regular activities a few days to weeks after surgery. Ask your provider for specific restrictions after the procedure.


Can heart block be prevented?

You may be able to prevent some causes of heart block, like heart disease.

Steps you can take to keep your heart and body as healthy as possible include:

  • Lead a heart-healthy lifestyle. This includes eating heart-healthy foods, getting regular physical activity, getting enough sleep each night, reducing stress, limiting alcohol and avoiding smoking and recreational drugs.
  • Talk with your provider about medications and other supplements you take. They can review what you’re taking to find out if any of them change the normal levels of certain substances in your body. (Potassium, calcium and magnesium play a role with your heart’s electrical system.) Your provider can change your medication to a different drug class if needed.

Outlook / Prognosis

What can I expect if I have heart block?

If you have first-degree heart block, ask your cardiologist or electrophysiologist what — if any — changes you need to make to your lifestyle or medications. This type of heart block doesn’t usually get in the way of your normal activities.

In general, a pacemaker won’t seriously restrict your ability to take part in sports and leisure activities. It’s important to follow your provider’s instructions for pacemaker monitoring so they can ensure your device is working correctly.

How long heart block lasts

The cause of your heart block determines how long it lasts. If you replace a medication that causes heart block, that can resolve the issue. But heart block from another cause will likely be a lifelong condition.

Outlook for heart block

Heart blocks can be serious. Without treatment, severe heart block can cause sudden cardiac arrest. But most commonly, untreated heart block can cause lightheadedness or fainting spells.

With treatment, your outlook depends on your age and what other conditions you have.

Living With

How do I take care of myself?

If you have a pacemaker:

  • Avoid close contact with magnetic devices and any device that sends out an electrical field. This includes staying at least 6 inches from cell phones. For example, don’t keep your cell phone in your shirt pocket.
  • When going through security screening stations (like airports and courthouses), tell the screeners that you have a pacemaker and should avoid the handheld wands. Always carry a card that states the type of pacemaker you have.
  • Tell all your healthcare providers and your dentist that you have a pacemaker. Some medical procedures, like magnetic resonance imaging (MRI), can interfere with pacemakers. A provider may need to reprogram your pacemaker after certain kinds of surgery.

When should I see my healthcare provider?

If you have a pacemaker, your cardiologist will want to check it periodically to make sure that it continues to work well. They can monitor you remotely, but you’ll need annual in-person appointments when your provider evaluates and adjusts your pacemaker.

Call your healthcare provider if you experience:

  • Dizziness or fainting.
  • Chest pain.
  • Racing heartbeat or skipped heartbeat.
  • Weakness.
  • Shortness of breath.
  • Swollen feet, ankles or legs.

When should I go to the ER?

You need immediate medical care if you have a heart attack or cardiac arrest. Let your family and co-workers know about your risk of these (and the symptoms) so they can call 911 or your local emergency number.

What questions should I ask my doctor?

Questions to ask your healthcare provider may include:

  • What type of heart block do I have?
  • Do I need treatment?
  • Which kind of treatment is best for me?
  • If my child has heart block from birth, will my future children have it at birth, too?

A note from Cleveland Clinic

It can be unnerving to have chest pain or have trouble catching your breath. But getting a heart block diagnosis can explain why you’re experiencing those symptoms. The good news is that people who need treatment can have success with medicines or pacemakers that keep their hearts in a normal rhythm. Be sure to ask your provider about anything that isn’t clear when discussing your treatment plan.

Medically Reviewed

Last reviewed on 04/14/2024.

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