Third Degree Atrioventricular Block

Third Degree Atrioventricular Block (complete block) is a condition that causes the signals that travel from the heart’s upper chambers (atria) to its lower chambers (ventricles) to be completely blocked. It is the most serious type of heart block. As a result, certain cells in the heart cause the ventricles to contract and pump blood (escape beats). These cells act as a sort of “backup system.” However, this backup system works at a much slower rate than normal, and it is not enough to keep your heart working well.

What are the causes?

This condition may be caused by:

• Any condition that damages the electrical pathway that controls the heart’s rate and rhythm, such as a heart attack.
• Some medicines that slow down the heart rate, such as beta blockers or calcium channel blockers.
• Surgery that damages the heart.
• Overstimulation of the nerve that slows down heart rate (vagus nerve). This cause is common among well-conditioned athletes.

Some people are born with this condition (congenital heart block), but most people develop it over time.

What increases the risk?

The risk for this condition increases with age. You are also more likely to develop this condition if you have:

• A history of heart attack.
• Heart failure.
• Coronary heart disease.
• Inflammation of heart muscle (myocarditis).
• Disease of heart muscle (cardiomyopathy).
• Infection of the heart valves (endocarditis).
• Infections or diseases that affect the heart. These include:
  • Lyme disease.
  • Sarcoidosis.
  • Hemochromatosis.
  • Rheumatic fever.
  • Certain muscle disorders.

Babies are more likely to be born with heart block if:

• The child’s mother has an autoimmune disease, such as lupus.
• The baby is born with a heart defect that affects the heart’s structure.
• A parent was born with a heart defect.

What are the signs or symptoms?

Symptoms of this condition include:

• Tiredness.
• Shortness of breath.
• Dizziness.
• Light-headedness.
• Fainting.
• Chest pain.

How is this diagnosed?

This condition may be diagnosed based on:

• A physical exam.
• Your medical history.
• A measurement of your pulse or heartbeat.
• Tests, which may include:
  • An electrocardiogram (ECG). This checks for problems with electrical activity in your heart.
  • Ambulatory cardiac monitoring. This is a portable ECG that you wear. It checks your heart’s rhythm.
  • An electrophysiology (EP) study. Long, thin tubes (catheters) are placed in your heart. The catheters give information about your heart’s electrical signals.

How is this treated?

This condition must be treated right away at a hospital. Treatment may involve:

• Treating an underlying condition, such as heart disease.
• Changing or stopping any heart medicines that may have caused heart block.
• Having a permanent pacemaker placed in your chest. A pacemaker uses electrical pulses to help the heart beat normally. It is usually placed under the skin on your chest or abdomen.

Follow these instructions at home:

Alcohol use

• Do not drink alcohol if:
  • Your health care provider tells you not to drink.
  • You are pregnant, may be pregnant, or are planning to become pregnant.
• If you drink alcohol, limit how much you have:
  • 0–1 drink a day for women.
  • 0–2 drinks a day for men.
    • Be aware of how much alcohol is in your drink. In the U.S., one drink equals one typical bottle of beer (12 oz), one-half glass of wine (5 oz), or one shot of hard liquor (1½ oz).

General instructions

• Take over-the-counter and prescription medicines only as told by your health care provider.
• Follow your health care provider’s recommendations to help reduce your risk for heart disease. This may include:
  • Exercising at least 30 minutes on 5 or more days each week (150 minutes). Ask your health care provider what type of exercise is safe for you.
  • Eating a heart-healthy diet with fruits and vegetables, whole grains, low-fat dairy products, and lean proteins like poultry and eggs. Your health care provider or dietitian can help you make healthy choices.
  • Maintaining a healthy weight.
• Do not use any products that contain nicotine or tobacco, such as cigarettes and e-cigarettes. If you need help quitting, ask your health care provider.
• Keep all follow-up visits as told by your health care provider. This is important.

Contact a health care provider if you:

• Feel like your heart is skipping beats.
• Feel more tired than normal.
• Have swelling in your lower legs or your feet.

Get help right away if you:

• Have symptoms that change or get worse.
• Develop new symptoms.
• Have chest pain, especially if the pain:
  • Feels like crushing or pressure.
  • Spreads to your arms, back, neck, or jaw.
• Feel short of breath.
• Feel light-headed or weak.
• Faint.

These symptoms may represent a serious problem that is an emergency. Do not wait to see if the symptoms will go away. Get medical help right away. Call your local emergency services (911 in the U.S.). Do not drive yourself to the hospital.

Summary

• Third-degree AV block, also called complete block, is the most serious type of heart block. In this condition, the signals that control heart rate are completely blocked.
• Third-degree heart block is a medical emergency that should be treated right away at a hospital.
• Treatment may include the placement of a temporary or permanent pacemaker, which uses electrical pulses to help the heart beat normally. It is usually placed under the skin on your chest or abdomen.