Third-degree heart block may be caused by:

• Damage to the heart from surgery

• Damage to the heart muscle from a heart attack

• Other types of heart disease that result in heart muscle damage

• Heart valve disease

• Other diseases, including rheumatic fever and sarcoidosis

• Some medicines

• Older age

In addition, some babies are born with heart block. Heart block may also run in families.

Symptoms of third-degree heart block may include:

• Lightheadedness, faintness, or dizziness

• Feeling tired

• Shortness of breath

Third-degree heart block is a serious condition that needs to be treated right away. Treatments for third-degree heart block include:

• Taking medicines to increase the heart rate for the short-term (acutely)

• Stopping medicines, if they are causing the heart block

• Getting a pacemaker

Third-degree heart block may cause a sudden loss of consciousness. It also may cause the heart to suddenly stop beating (sudden cardiac arrest).

Call your healthcare provider right away if you have any of these:

• Unusual tiredness

• Shortness of breath

• Chest pain

• Weakness, dizziness, or fainting

• Unusual drowsiness or confusion

• Pain that gets worse

• Symptoms that don’t get better with treatment, or symptoms that get worse

• New symptoms