Heart Block

Causes of heart block

Heart block can develop due to:

• Medications, such as the blood pressure drugs known as beta-blockers and calcium channel blockers
• Heart diseases, such as cardiomyopathy and heart valve disease
• A heart attack that damages the heart's electrical system
• Heart surgery
• Certain infections, such as Lyme disease

People can be born with heart block, but it's rare. When present at birth, it may be associated with a heart defect or with their parent having an autoimmune condition, such as lupus, during pregnancy.

Types of heart block

There are three types of heart block, which range from mild to severe.

• First-degree heart block. This is the least severe form. The electrical signal travels from the atria to the ventricles, but it is slower than normal.
• Second-degree heart block. The electrical signal may not reach the ventricles, resulting in slow or skipped heartbeats.
• Third-degree heart block. The electrical signal doesn't reach the heart's lower chambers. As a result, the ventricles beat much more slowly than normal, the upper and lower chambers don't beat one after the other as they're supposed to, and the heart can't pump enough blood to the rest of the body. Also called complete heart block, this is the most severe type and can be life-threatening.

Symptoms of heart block

People with first-degree heart block may have no symptoms. In fact, some patients only learn they have it when they undergo a heart test called an electrocardiogram, or ECG, and it's discovered by chance.

Those with second- or third-degree heart block may notice any of the following signs:

• Dizziness
• Fainting or feeling faint
• Tiredness
• Chest pain
• Shortness of breath
• Heart palpitations (a sense that the heart is beating abnormally hard, fast or irregularly)

Diagnosis of heart block

In addition to asking questions about your health history and performing a physical exam, your doctor may order one or more of the following tests:

• Electrocardiogram (ECG or EKG). By recording the heart's electrical activity, the ECG helps doctors diagnose arrhythmias (problems with heart rhythm) and heart damage.
• Holter monitor. A Holter monitor is a small, portable device that continuously records your heart rhythms as you go about your daily activities. You'll need to wear it for one to two days. A Holter monitor can detect heart rhythm problems that aren't caught by a short ECG test.
• Event monitor. This small device may be worn for several weeks. You activate it to record your heart rate and rhythm whenever you feel symptoms. Event recorders are good for patients who don't experience symptoms frequently.
• Electrophysiology (EP) study. This minimally invasive procedure allows doctors to assess your heart's electrical system and activity.

Treatment of heart block

If you have first-degree heart block, you probably won’t need treatment. You should have regular checkups, though.

If you have second- or third-degree heart block, you may need a small implantable device called a pacemaker. Pacemakers mimic the body's electrical system by sending out painless electrical pulses that stimulate the heart to contract. This helps keep the heart beating at a normal rhythm and rate.

Heart block that developed due to a heart attack or heart surgery may go away as you recover. If medications are causing your heart block, consult your doctor about whether it's an option to stop or switch your medications.