Bundle branch block: Symptoms and causes

Bundle branch block is where a blockage or delay is present along the pathway that electrical impulses travel to produce a heartbeat. Blood is therefore likely to be less efficient in circulating.

The delay or blockage can occur on the pathway that sends electrical impulses either to the left or the right side of the bottom chambers (ventricles) of the heart.

Many patients don’t require any treatment at all for bundle branch block. However, it may point to other conditions such as heart disease or circulatory issues that will require management.


Bundle branch block doesn’t generally show symptoms so most people don’t know they’ve got it. However, fainting (syncope) or feeling faint (presyncope) could be a sign.


Electrical impulses within the heart muscle are responsible for causing it to beat (contract). These impulses travel along either the right or the left bundles. If one or both branch bundles become damaged, for example due to heart attack, the electrical pulses will be blocked off. This in turn will cause can abnormal heartbeat.

The cause behind bundle branch blocks largely depends on whether the right or left bundle branch is affected. However, there may well be no obvious cause.

Causes can include:

  • Heart attack (myocardial infarction)
  • Left bundle branch block
  • Right bundle branch block
  • Heart attack (myocardial infarction)
  • High blood pressure (hypertension)
  • High blood pressure in the pulmonary arteries (pulmonary hypertension)
  • Blood clot in the lungs (pulmonary embolism)
  • Inflammation of the heart muscle (myocarditis)
  • Thickened, weakened or stiffened heart muscle (cardiomyopathy)
  • Heart defects that are present at birth (congenital) eg. a hole in the wall separating the upper chambers of the heart (atrial septal defect)

Risk factors

There are a couple of key risk factors for bundle branch block. They include:

  • Underlying health problems such as high blood pressure
  • Older age. Bundle branch block is not so common in younger people – it’s more common in those over 50

Could you confidently spot a potential case of bundle branch block?

It’s not always easy, but where symptoms are affecting a patient’s health and quality of life it’s essential to diagnose and treat bundle branch block effectively.

At PDUK we look at this in a couple of our courses.

The first is The ABC of ECGs. Aims specifically at nurses of every discipline, the course is held online making it ideal for learning flexibly. As it’s remote, you can easily fit it around work shifts and family life.

Worth 8 hours of CPD held over one day, community-based practitioners especially will benefit from a practical step-by-step review of ECG interpretation. The emphasis is on understanding the basis of ECG interpretation, clinical pearls and potentially life-threatening problems.

Then you’ve got our The patient, the clinician, the ECG course. Again, held online and offering a great opportunity to network, this training course is designed for practitioners and doctors looking for a more comprehensive ECG skills and arrhythmia recognition course. Also held over two days and worth 16 valuable hours of CPD to help you support your patients in the best way possible.

All course materials are included but spaces fill up fast on both courses so make sure you sign up today!