What Is Heart Block?

Medically Reviewed by James Beckerman, MD, FACC on February 04, 2021

Your heart isn’t plugged into an outlet. And you don’t use a switch to turn it on. But just like a lamp, your heart runs on an electrical system.

Every time your heart beats, an electrical signal travels from the upper to the lower chambers. Along the way, the signal tells your heart to contract and pump blood.

When that signal is slowed down or kept from sending its message, it causes a condition called heart block. This affects the rate and rhythm of your heart, or the number of times it beats and the pattern of those beats.


Some people are born with heart block. In others, it develops later in life.

If you’re born with it, it’s called congenital heart block. Causes include:

  • An autoimmune disease. Diseases, such as lupus, can be passed by your mother in certain proteins through the umbilical cord.
  • A birth defect. Your heart may not have developed correctly in the womb. Doctors often don’t know what causes these birth defects.

If you have heart block that you weren’t born with, doctors call it “acquired” heart block. It’s the most common type. Causes include:

If medicine is the cause, a dosage change or prescription switch could correct the problem. Some of the other medical issues may correct themselves.

Degrees of Heart Block

Doctors group heart block into categories based on how severe it is.

First degree. This is the mildest form of heart block. The heart’s electrical signal is slowed but still gets where it’s going. You may not notice or need treatment.

Second degree. Some of the signals don’t get to the right places. This may mean your heart beats more slowly or drops beats. It can be asymptomatic or symptomatic.

Third degree (also called complete). No electrical messages get through. The rate and rhythm of your heartbeat is very slow or it may even stop entirely. This type of heart block can be fatal.


Your symptoms depend on the type of heart block you have. If you have first degree, you may not have any at all.

Second-degree symptoms may include:

Third-degree heart block needs immediate medical attention. Call 911 for any:

Who’s At Risk?

Heart block can happen to anyone. It’s more common in older people because it’s often a result of other heart issues. Those with heart block also may have:


Your doctor will take these factors into account:

  • Current health
  • Any medications you are taking
  • Family history of heart issues
  • Health history
  • Tobacco, drug, and alcohol use
  • Symptoms

After a physical exam, your doctor will use an EKG, or electrocardiogram, to check your heart’s electrical activity. They may also ask you to wear a monitor, called a Holter, for anywhere from a day to a month to track the rhythm of your heart.


For second- and third-degree heart block, you may get a small device called a pacemaker in your chest. This is considered “minor” surgery and you’ll be sedated for it. Like a backup electrical system, it reminds the heart to beat at a normal rate if it slows or stops.

Life After Heart Block

Just like your heart, your pacemaker needs to be treated right to work well. There are some things you can do to get the most out of it:

  • Know what kind of pacemaker you have.
  • Let all your health care providers know about your pacemaker.
  • Wear a medical bracelet or necklace, to inform others of your pacemaker in an emergency.
  • Stay away from electrical devices with strong magnetic fields.
  • It’s fine to be active once you have your doctor’s OK, but skip contact sports like football or ice hockey.
  • Get your pacemaker checked regularly to make sure it’s working well.

Show Sources


National Heart, Lung, and Blood Institute: “Heart Block.”

Johns Hopkins Medicine: “What Is Heart Block?”

Mayo Clinic: “Bradycardia.”

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