Health Encyclopedia

Heart Block

Electrical signals control the beating of your heart. They tell your heart muscle when to contract, a process known as conduction. When you have heart block, there is interference with the electrical signals that usually move from the top chambers of your heart (the atria) to the bottom chambers of your heart (the ventricles), telling it when to beat. This is known as a conduction disorder. If the electrical signals can’t move from the atria to the ventricles, they can’t tell the ventricles to contract and pump blood correctly.

In most cases of heart block, the signals slow down, but do not completely stop. Heart block is categorized as first-, second-, or third-degree:

  • First-degree heart block is the least severe. The electrical signals slow down as they move from your atria to your ventricles. First-degree heart block might not require treatment of any kind. However, you may be at higher risk of developing another type of irregular heartbeat, or arrhythmia, called atrial fibrillation.

  • Second-degree heart block means that the electrical signals between your atria and ventricles are even slower than in first-degree heart block. There are two types of second-degree heart block:

    • Mobitz type I: The electrical signals get slower and slower between beats. Eventually your heart skips a beat. You may feel dizzy.

    • Mobitz type II: The electrical signals sometimes get to the ventricles, and sometimes they do not. You may require a pacemaker, a small machine that provides regular electrical pulses to manage your heart’s rhythm.

    • Third-degree heart block is the most severe. Electrical signals do not go from your atria to your ventricles at all with this type. Third-degree heart block prevents your heart from pumping blood through your body, and this can cause cardiac arrest and death. You may need emergency treatment to save your life. Third-degree heart block usually requires lifelong treatment with an implanted pacemaker.

If you are born with heart block, you have congenital heart block. Either a condition your mother had during her pregnancy, or heart problems you were born with, cause this condition.

Many instances of heart block occur because of some other condition or event. A heart attack, which damages your heart muscle, is the most common cause. Surgery, medications, and diseases such as rheumatic fever or sarcoidosis are also possible causes.

Symptoms

Symptoms depend on the type of heart block you have:

  • First-degree heart block may have no bothersome symptoms.

  • Second-degree heart block might cause:

    • Dizziness

    • Fainting

    • The feeling that your heart skips beats

    • Chest pain

    • Difficulty breathing or shortness of breath

    • Nausea

    • Fatigue

Third-degree heart block, which can be fatal, might cause 

  • Intense tiredness

  • Irregular heartbeats

  • Dizziness

  • Fainting

  • Cardiac arrest

 Who’s at risk

Your chances of developing heart block are greater if you: 

  • Were born with heart defects

  • Were born to a mother with an autoimmune disease

  • Have recently had heart attacks or heart surgery

  • Have coronary artery disease

  • Have rheumatic fever

  • Have heart muscle diseases or inflammation

  • Have sarcoidosis, degenerative muscle disorders, Lev’s disease, or Lenegre’s disease

  • Are taking certain medications, including digitalis, beta blockers, and calcium channel blockers

  • Have an overactive vagus nerve

Diagnosis

To diagnose your condition, your physician will consider:

  • Your overall health and medical history

  • Any family history of heart block or heart disease

  • Medications you are taking

  • Lifestyle choices, such as use of cigarettes or illegal drugs

  • Your description of symptoms

  • A physical exam

  • An electrocardiogram (ECG) that records your heart’s electrical impulses

  • Testing with a Holter or event monitor to track your heart’s rhythm for a period of time. You might wear a Holter monitor for 24 or 48 hours, or an event monitor for a month or more. These help capture changes in your heart’s rhythm, even if they do not occur often or predictably.

  • An electrophysiology study, which is an outpatient procedure in which a thin, flexible wire is threaded from your groin or arm to your heart to track changes in rhythm

Treatment

You treatment depends on the type of heart block you have:

  • With first-degree heart block, you might not need treatment.

  • With second-degree heart block, you may need a pacemaker.

  • With third-degree heart block, you will need a pacemaker for the rest of your life.

In addition, your medical team may make changes in any prescription medications you're taking.

Complications

Complications are problems your condition causes. With heart block, these could include the development of other types of arrhythmias, such as atrial fibrillation, or cardiac arrest. Some cases of heart block also can be fatal. 

Prevention

You may sometimes prevent heart block — in your baby, for example. If you are a woman with an autoimmune disease and give birth, your baby has an increased risk of developing heart block. Tests during your pregnancy, however, can tell your doctor whether your baby needs medication to reduce the chances of severe heart block.

It's also important to follow your doctor’s orders exactly when you take medications that increase your risk for heart block, or when you’re recovering from a heart attack or heart disease. A healthy lifestyle contributes to overall good health — including heart health. Exercise, eat a well-balanced diet, and don’t smoke.

When to call the doctor

Seek immediate medical attention for these symptoms:

  • Extreme tiredness

  • Dizziness

  • Fainting or loss of consciousness

  • Shortness of breath

  • Chest pain

If you experience sudden cardiac arrest, you will obviously not be able to seek care for yourself. It is critically important to make sure the people you see on a regular basis know what to do in an emergency. Calling 911 is the most important first step.

How to manage or live with the condition

Follow your doctor’s recommendations for taking medication and using a pacemaker, if that applies to you. Also, always keep follow-up appointments to make sure your treatment is on track.

To improve your quality of life with a pacemaker, you may need to:

  • Avoid situations in which your pacemaker may be disrupted, such as being near an electrical device or devices with magnetic fields.

  • Carry a card that lets people know what kind of pacemaker you have.

  • Tell all of your health care providers that you have a pacemaker.

  • Get pacemaker tune-ups to make sure your device is working well

  • Stay active, but avoid contact sports.

  • Wear a medical alert bracelet or necklace.



Medical Reviewers:

  • Fraser, Marianne, MSN, RN
  • Sohrabi, Farrokh, MD