Bundle branch block is a condition in which there's a delay or obstruction along the pathway that electrical impulses travel to make your heart beat. The delay or blockage may occur on the pathway that sends electrical impulses to the left or the right side of the bottom chambers (ventricles) of your heart.

Bundle branch block sometimes makes it harder for your heart to pump blood efficiently through your circulatory system.

There's no specific treatment for bundle branch block itself. However, any underlying health condition that caused bundle branch block, such as heart disease, will need to be treated.

In most people, bundle branch block doesn't cause any symptoms. Sometimes, people with the condition don't even know they have a bundle branch block.

For those people who do have signs and symptoms, they may include:

  • Fainting (syncope)
  • Feeling as if you're going to faint (presyncope)

When to see a doctor

If you've fainted, see your doctor to rule out any serious, underlying causes.

If you have heart disease, or if your doctor has already diagnosed you as having bundle branch block, ask your doctor how often you should have follow-up visits. You might want to carry a medical alert card that identifies you as having bundle branch block in case you're seen in an emergency by a doctor who isn't familiar with your medical history.

Normally, electrical impulses within your heart's muscle signal it to beat (contract). These impulses travel along a pathway, including the right and the left bundles. If one or both of these branch bundles become damaged — due to a heart attack, for example — this change can block the electrical impulses and cause your heart to beat abnormally.

The underlying cause for bundle branch blocks may differ depending on whether the left or right bundle branch is affected. It's also possible that this condition can occur without any known underlying cause. Specific causes may include:

Left bundle branch block

  • Heart disease
  • Thickened, stiffened or weakened heart muscle (cardiomyopathy)
  • A viral or bacterial infection of the heart muscle (myocarditis)
  • High blood pressure (hypertension)

Right bundle branch block

  • A heart abnormality that's present at birth (congenital) — such as atrial septal defect, a hole in the wall separating the upper chambers of the heart
  • A heart attack (myocardial infarction)
  • A viral or bacterial infection of the heart muscle (myocarditis)
  • High blood pressure (hypertension)
  • A blood clot in the lungs (pulmonary embolism)

Risk factors for bundle branch block include:

  • Increasing age. Bundle branch block is more common in older adults than in people who are middle-aged.
  • Underlying health problems. People who have high blood pressure or heart disease are more likely to have bundle branch block than people without those conditions.

The main complication of bundle branch block is a slow heart rate, which can sometimes cause fainting.

People who have a heart attack and develop a bundle branch block have a higher chance of complications, including sudden cardiac death, than do people who have heart attacks and don't develop a bundle branch block.

Because bundle branch block affects the electrical activity of your heart, it can sometimes complicate the accurate diagnosis of other heart conditions, especially heart attacks, and lead to delays in proper management of those problems.

You're likely to start by first seeing your primary care doctor. However, you may then be referred to a doctor who specializes in heart disorders (cardiologist).

Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

  • Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your caffeine intake before having heart function tests.
  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Write down key personal information, including any major stresses or recent life changes.
  • Make a list of all medications, vitamins and supplements that you're taking. Also, write down the dose that you're taking.
  • Ask a family member or friend to come with you, if possible. Sometimes it can be difficult to remember all of the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
  • Write down questions to ask your doctor.

Preparing a list of questions can help you make the most of your time with your doctor. For bundle branch block, some basic questions to ask your doctor include:

  • What are the most likely causes of my symptoms?
  • What kinds of tests do I need? Do these tests require any special preparation?
  • What treatments are available, and which do you recommend?
  • Will the bundle branch block return after treatment?
  • What types of side effects can I expect from treatment?
  • I have other health conditions. How can I best manage these conditions together?
  • Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

  • When did you first begin experiencing symptoms?
  • Does anything seem to improve your symptoms?
  • What, if anything, appears to worsen your symptoms?
  • Has a doctor ever told you that you have a bundle branch block?

Tests that may be used to diagnose a bundle branch block or the underlying problem causing it include:

  • Electrocardiogram. An electrocardiogram records the electrical impulses in your heart through wires attached to the skin on your chest and other locations on your body. Abnormalities may indicate the presence of bundle branch block, as well as which side is being affected.
  • Echocardiogram. An echocardiogram can be used to pinpoint an underlying condition that caused the bundle branch block. This test uses sound waves to produce images of the heart, allowing your doctor to see your heart in motion.

    An echocardiogram provides detailed images of the heart's structure and shows the thickness of your heart muscle and whether your heart valves are moving normally.

Most people with bundle branch block are symptom-free and don't need treatment.

However, if you have an underlying heart condition causing bundle branch block, treatment of the underlying condition is recommended. Treatment of underlying conditions may involve using medications to reduce high blood pressure or lessen the effects of heart failure, or the use of a coronary angioplasty to open up the artery leading to your heart.

Additionally, depending on your symptoms and whether you have other heart problems, your doctor might also recommend:

  • A pacemaker. For some people with bundle branch block and a history of fainting, doctors may recommend implanting a pacemaker. A pacemaker is a compact device implanted under the skin of your upper chest (internal pacemaker) with two wires that connect to the right side of your heart. The pacemaker provides electrical impulses when needed to keep your heart beating regularly.
  • Cardiac resynchronization. Also known as biventricular pacing, this procedure is similar to having a pacemaker implanted. However, in cardiac resynchronization, there's a third wire that's connected to the left side of the heart so the device can keep both sides in proper rhythm.
April 10, 2015