Heart Block

What is heart block?

Heart block is a problem with the heartbeat. It happens when electrical impulses have trouble passing from the atria (upper chambers of the heart) to the ventricles (the heart's lower chambers).

Every normal heartbeat starts in a group of cells in the right atrium called the sinus node. These "pacemaker" cells send a regular electrical impulse to start the contraction of the heart in the atria. Normally the impulse then travels to the ventricles and they contract. Heart block may keep the contractions of the atria from coordinating with the contractions of the ventricles. It can cause a very slow heart rate.

There are various degrees of heart block:

• In first-degree heart block, the passage of impulses is delayed, but the delay does not cause symptoms. First-degree heart block is fairly common. Even teenagers, young adults and well-trained athletes may have it.
• In second-degree heart block, some of the atrial impulses fail to reach the ventricles. The pulse becomes slow or irregular.
• In third-degree block (complete heart block), no atrial impulses reach the ventricles, and the ventricles beat very slowly. The heart may not be able to pump enough oxygenated blood to the brain and the rest of the body. This can cause a number of symptoms.

How does it occur?

The most common cause of heart block is aging of the heart. It may also be a congenital problem (birth defect).

Heart block can be a symptom of heart disease. Heart blocks may be caused by:

• heart attacks
• coronary artery disease
• rheumatic fever
• overdose of some heart drugs
• infectious diseases of the heart, such as endocarditis.

A block that has existed for a long time may not mean that there is a problem. A block that appears suddenly may be a sign of a new heart problem or worsening of an existing one. Sometimes heart block can come and go.

What are the symptoms?

First-degree heart block does not cause any symptoms.

Second-degree heart block may not cause symptoms. Second-degree block can sometimes worsen to third degree.

Third-degree heart block is a serious condition that usually affects the heart's ability to pump blood effectively. Symptoms include:

• fainting
• dizziness
• tiredness
• low blood pressure when you stand up
• shortness of breath.

Third-degree heart block can cause sudden heart failure. Symptoms of heart failure are severe trouble breathing, a suddenly irregular or very fast heartbeat with lightheadedness or nausea, and foamy, pink mucus coughed up. It is a very serious problem that requires emergency medical care.

How is it diagnosed?

Heart blocks can be diagnosed with an electrocardiogram (ECG). Heart blocks have a certain pattern of electrical activity, which the ECG records. In some cases, an electrophysiologic study (EPS) may be done. This test uses probes placed in the heart to measure the flow and direction of electricity. A Holter monitor can also be used to diagnose the problem. The Holter monitor is a portable ECG that you can carry with you for 1 to 3 days to record your heart's electrical activity over time.

How is it treated?

Treatment depends on the degree of heart block you have. Many times heart block is not treated at all. If the block becomes severe, usually you will need an artificial pacemaker implanted in your chest. A pacemaker is an electronic device placed under the skin on the chest. It helps the heart maintain a regular beat.

How long will the effects last?

Depending on the cause, heart block can come and go, or you may have it once and then never again. For many people, especially those who have second or third-degree heart blocks, the block is continuous and does not change without treatment.

How can I take care of myself?

There is no specific way to prevent heart block, but having a healthy lifestyle can help prevent heart disease.

• Eat healthy food that is low in fat and sodium.
• Lose weight if you need to and maintain the lower weight.
• Exercise regularly, according to your provider's instructions.
• If you smoke, quit.
• Keep your cholesterol at a normal level.
• Keep your blood pressure under control.

Call your healthcare provider if:

• You are having symptoms such as lightheadedness, fainting, and shortness of breath.