What is heart block?

A heart block is a problem with your heart's electrical system. Normally, a small area of the heart (sinus node) creates the electrical signals that cause the heart to beat in a timed and regular way. A heart block occurs when the signal is blocked. This disrupts the heartbeat. A heart block does not mean that blood flow to the heart is blocked.

Heart block can be caused by many things that affect the electrical system of the heart. These things include the effects of aging, certain medicines, and certain health conditions.

There are three types of heart blocks. In a first-degree heart block, the signal is slower than normal. But the heart rate is normal, and the heart usually is not damaged.

In a second-degree heart block, some signals do not reach the lower chambers of the heart. This can cause the heart to skip a beat or have an abnormal rhythm.

In a third-degree heart block, the signal is completely blocked from reaching the lower chambers. This can cause the heart to slow down a lot or even stop beating. It is a very serious condition.

How heart block is treated can depend on the type and what is causing it. Treatment can also depend on your symptoms. If heart block doesn't cause symptoms, it may not be treated. Treatment may be a pacemaker. You and your doctor can decide what treatment is right for you.

Heart block of the atrioventricular (AV) node can be of several types, and a doctor generally can diagnose these by looking at the person's electrocardiogram (EKG, ECG).

First-degree AV block

In first-degree block, the electrical impulses take longer to travel between the upper chamber (atrium) and lower chamber (ventricle) of the heart. This type of heart rhythm may or may not be associated with a slow heart rate.

It does not usually require treatment. But this type of heart block may raise your risk of heart rhythm problems, such as atrial fibrillation.

Second-degree AV block

In second-degree heart block, some of the electrical impulses are blocked between the upper and lower chamber of the heart. These electrical impulses may or may not have a clear pattern. The blocking of the impulse can come and go, resulting in "dropped heartbeats."

Second-degree heart block can be categorized into two types:

• Mobitz type I block (also called Wenckebach) usually occurs in the AV node. It can happen in young, healthy people. It may also be caused by certain medicines or health conditions. It usually does not cause symptoms.
• Mobitz type II block usually occurs below the AV node in other conduction tissue. It can happen in people who have heart disease or have had a heart attack. It can also be caused by certain medicines or a heart procedure. It may cause lightheadedness or fainting (syncope). And it may progress to complete heart block.

How second-degree AV block is treated can depend on the type and what is causing it. Treatment can also depend on your symptoms. Treatment may be a pacemaker. If heart block doesn't cause symptoms, it may not be treated.

Complete or third-degree block

In third-degree heart block, all of the electrical impulses are completely blocked between the upper and lower chambers of the heart. When this occurs, the atria and ventricles beat at completely different rates.

Complete heart block can be caused by many things. These include scarring of the electrical system of the heart, certain heart diseases, and infections. It may also occur after a heart surgery or heart procedure. It can be present from birth (congenital).

Complete heart block can cause symptoms such as shortness of breath, lightheadedness, or fainting. Treatment is typically a pacemaker.

Bundle branch block

Bundle branch block can affect the heart's rhythm. The heart has structures, like wires, that are called bundle branches. They are part of the heart's electrical pathway. When a branch is diseased, it is called "blocked," because the electrical signals can't travel down the branch.

Some people with bundle branch block don't have any symptoms and don't need treatment. But when a block causes the heart to beat too slowly, it can cause symptoms such as tiredness and fainting. A pacemaker may be used to get the heartbeat back to normal.

• If you feel lightheaded, sit or lie down to avoid injury that might occur if you faint and fall.
• Have a heart-healthy lifestyle.
  • Eat a heart-healthy diet that includes vegetables, fruits, nuts, beans, lean meat, fish, and whole grains. Limit alcohol, sodium, and sugar.
  • Get regular exercise. Try for 30 minutes on most days of the week. If you do not have other heart problems, you likely do not have limits on the type or level of activity that you can do. You may want to walk, swim, bike, or do other activities. Ask your doctor what level of exercise is safe for you.
  • Stay at a weight that's healthy for you. Talk to your doctor if you need help losing weight.
  • Try to get 7 to 9 hours of sleep each night.
  • Try to quit or cut back on using tobacco and other nicotine products. This includes smoking and vaping. If you need help quitting, talk to your doctor about stop-smoking programs and medicines. These can increase your chances of quitting for good. Try to avoid secondhand smoke too.
  • Manage other health problems such as high blood pressure, high cholesterol, and diabetes. If you think you may have a problem with alcohol or drug use, talk to your doctor.
• If you received a pacemaker or an implantable cardioverter-defibrillator (ICD), you will get more information about it.
• Wear medical alert jewelry that describes your condition and says you have a pacemaker or ICD. You can buy this at most drugstores.

Heart block can be caused by many things that affect the electrical system of the heart. Examples include:

• Scarring (fibrosis) of the heart's electrical system, which may be related to aging. This is a common cause of heart block.
• Heart attacks.
• Infections.
• Myocarditis.
• Congenital heart disease.
• Use of certain medicines, such as beta-blockers, calcium channel blockers, and digoxin.
• Heart surgery or heart catheter procedures.

Heart block is more common in older people and may be the result of age and a combination of factors listed above.

Heart block refers to an abnormality in the way electricity passes through the normal electrical pathways of the heart. The abnormality "blocks" the electrical impulse from continuing through the normal pathways and usually results in a slower heart rate.

The electrical activity of the heart starts in the sinoatrial (SA) node in the upper chamber (atrium) and travels through the atrioventricular (AV) node to reach the lower chamber (ventricle). Heart block may occur at any point along this electrical pathway.