Overview

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.

Symptoms

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.

Causes

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

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.

Complications

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.

April 10, 2015
References
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