Bundle Branch Block

1 What is Bundle Branch Block?

A bundle branch block is defined as a condition in which there is complete or partial blockage along the pathway that transmits electrical impulses to the left or the right side of the bottom chambers of your heart (ventricles) to make your heart beat.

Bundle branch block makes it difficult for your heart to pump enough blood through your circulatory system.

An underlying health problem such as heart disease needs to be treated, as there is no specific treatment available for bundle branch block itself.

2 Symptoms

Bundle branch block occurs in most people without causing any signs or symptoms.

There will be no symptoms if there are no other problems in your heart.

Symptoms, when they do occur, include:

  • Fainting (syncope)
  • Feeling as though you are about to faint (presyncope)

When to see a doctor

If you have had fainting spells, consult your doctor to rule out any other serious, underlying causes.

If you have a heart problem or if you have been diagnosed with bundle branch block, ask your doctor about the frequency of your follow-up visits.

You may need to carry a medical alert card with you that identifies that you have bundle branch block, in case you are seen by a doctor who is unfamiliar with your medical history during an emergency.

3 Causes

The underlying cause for bundle branch blocks varies, and depends on the branch– the left or the right bundle branch– that is affected.

Sometimes, bundle branch block can occur without any known underlying cause.

Specific underlying causes may include:

Left bundle branch block

Right bundle branch block

  • Congenital heart disease — such as defects in the wall between the upper chambers or lower chambers of your heart (atrial septal defect and ventricular septal defect)
  • A heart attack (myocardial infarction)
  • Cardiomyopathy
  • A viral or bacterial infection of the heart muscle (myocarditis)
  • High blood pressure (hypertension)
  • Chronic lung disease
  • Blood clot in the lungs (pulmonary embolism)

An electrical impulse, which is produced within your heart's muscle signals the heart to contract or beat.

These impulses then travel across your heart along a pathway that includes the right and the left bundles of His.

If there is damage in one or both of these branch bundles because of a heart attack, then, it can result in blockage of the electrical impulses and make your heart to beat abnormally.

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