Bundle Branch Block

A bundle branch block (BBB) is a blockage or disruption of the electrical signal that makes your heart beat. This block leads to an abnormal heart rhythm. Bundle branch blocks are common, especially in people with heart failure.

After your heart’s tissue sends electrical impulses through the top two chambers of your heart (atria), the impulses travel through pathways called bundle branches. These impulses normally move through the bottom two chambers of your heart (ventricles). The ventricles usually beat (contract) at the same time.

But a bundle branch block delays the electrical signal to one of the ventricles, making it contract later than the other. When you have a bundle branch block, the signals first travel to the healthy ventricle and then activate the other ventricle through heart muscle tissue, which takes longer.

You may faint or feel short of breath with this condition. Medicine or a pacemaker can help with these symptoms. Healthcare providers don’t always treat bundle branch blocks and may simply monitor them over time. But they may treat the underlying health problems that cause the block.

Types of this condition

There are two types of bundle branch blocks:

• Right bundle branch block (RBBB): RBBB occurs when there’s a disruption along the pathway that sends electrical signals to your right ventricle.
• Left bundle branch block (LBBB): LBBB occurs when there’s a disruption along the pathway that sends electrical signals to your left ventricle. Having this condition often means that you have an underlying heart problem.

You can have a disruption in one or both bundle branches at the same time.

Symptoms of bundle branch block

A bundle branch block often doesn’t cause any symptoms. You’re more likely to feel symptoms if you have an underlying heart condition, a severe case or a block on both sides. Bundle branch block symptoms may include:

• Dizziness
• Fainting
• Fatigue
• Feeling like you’ll faint (presyncope)
• Heart palpitations

Bundle branch blockages on both sides may cause symptoms that include:

• Abnormal heartbeat (arrhythmia)
• Shortness of breath
• Slow heart rate (bradycardia)

Bundle branch block causes

Conditions that can cause a bundle branch block include:

• Congenital heart disease
• Heart attack
• Heart disease (coronary artery disease)
• Heart failure
• Heart infection (myocarditis)
• Heart valve disease
• High blood pressure
• Scarring (fibrosis) from aging or disease
• Weakened or stiffened heart muscle (cardiomyopathy)

Right bundle branch block may also result from lung diseases, including:

• Chronic obstructive pulmonary disease (COPD)
• Pulmonary embolism
• Pulmonary hypertension (PH)

Sometimes, a bundle branch block has no known cause. It can happen in people whose hearts otherwise function normally and who have no underlying conditions.

Risk factors

Anyone can have a bundle branch block. But you’re more likely to have it if you:

• Are over 70
• Are white
• Are male
• Have other health conditions, like heart disease

Complications of this condition

When your ventricles contract at different times, it’s harder for your heart to pump blood efficiently. Bundle branch block complications (usually from the left type) may include:

• Abnormal heart rhythms that are too fast
• Problems with your ventricle’s function
• Worse heart failure
• Complete heart block

How doctors diagnose this condition

Healthcare providers diagnose bundle branch block with two main tests:

• Electrocardiogram (EKG): During an EKG, a computer records a tracing of electrical impulses that travel through your heart. An EKG can also show which side of your heart has the bundle branch block.
• Echocardiogram: During this test, sound waves create pictures of your heart’s chambers and valves. Your provider can see the motion and rhythm of your heart as it beats. They can also check for heart disease and other underlying conditions.

If your provider diagnoses you with BBB, they may (on rare occasion) want to do an electrophysiology study. This can tell them if your case is likely to get worse. They’ll also check you for related health conditions. They may recommend these tests:

• Blood pressure reading to look for high blood pressure (hypertension) or low blood pressure (hypotension)
• Blood test to check cholesterol levels
• Cardiac catheterization to look at the blood vessels in your heart
• Nuclear cardiac stress test to look for coronary artery (heart) disease
• Pulmonary function testing to see how well your lungs are working

How is it treated?

If you don’t have symptoms or underlying conditions, you may not need treatment for bundle branch block. But if you do, treatments may include:

• Medication: This manages issues like high blood pressure or heart failure symptoms.
• Pacemaker: This helps with symptoms like fainting.
• Biventricular pacemaker: This helps both of your ventricles contract at the same time and improves symptoms like shortness of breath.
• Implantable cardioverter defibrillator (ICD): This benefits people at high risk of cardiac arrest.

If you get a pacemaker or an ICD, you’ll likely stay overnight in the hospital. You can return to your routine within a few days. Complete recovery takes several weeks.

When should I see my healthcare provider?

See your provider if you have any new symptoms or your symptoms get worse. Chest pain along with a new left bundle branch block may be a sign of a serious underlying health condition, like a heart attack.

Seek medical treatment right away if you have:

• Chest pain, discomfort or tightness in your chest
• Extreme fatigue
• The feeling that you’re going to pass out
• Loss of consciousness
• Shortness of breath or difficulty breathing

If you see a new healthcare provider, always tell them that you have a bundle branch block. This information will help them better monitor your heart health and overall wellness.

Make sure your provider knows about your BBB diagnosis anytime you have:

• An exercise stress test, as an LBBB can make diagnosis of certain conditions more difficult
• A medical emergency, like a heart attack
• Surgery for another heart condition

What can I expect if I have this condition?

You’ll have a bundle branch block for the rest of your life. The block may either stay the same or worsen over time.

Having a bundle branch block usually won’t affect your work. But that can change if you have severe symptoms.

If you have no underlying conditions, bundle branch block may not affect your overall health or lifespan. If you have other heart conditions, BBB can worsen your symptoms.

Most people with a bundle branch block can lead full lives, though their risk of death may increase if they have other heart problems. You’re at a higher risk of death if you have a bundle branch block along with a heart attack or heart failure.