About your heart

Bundle branch block

A bundle branch block is either a complete or a partial interruption of the electrical pathways inside the wall of the heart between the two lower chambers (ventricles).

The pacemaker of the heart is the sino-atrial node, a small mass of muscle cells at the top of the right chamber (atrium) of the heart. It creates an electrical signal that travels through the heart muscle and causes the atria to contract and pump blood into the lower chambers. Shortly after the sino-atrial node releases its signal, it is received by the atrio-ventricular node, which in turn sends a signal to the ventricles causing them to contract and pump blood out of the heart. The muscle fibres that carry the signal from the atrio-ventricular node go into the wall that divides the ventricles and then splits into two branches, the bundle branches.

Symptoms of bundle branch block

Bundle branch blocks usually do not cause symptoms. They are not considered to be irregular heartbeats or arrhythmias.

Right bundle branch block occurs in normal, healthy individuals. If it happens with a heart attack, it may be a sign of serious heart muscle damage.

A block of the right bundle branch may cause an electrocardiogram to be distorted. The distortion usually is not enough to make diagnosing a heart attack difficult. It may be a sign of worsening heart conditions. It can also appear after an embolism in the lung (pulmonary embolus).

A block in the left bundle branch can sometimes be benign and not cause problems. However, it always interferes with using an electrocardiogram to diagnose heart disease.

Causes of bundle branch block

Bundle branch block is a common disorder. It occurs in many medical conditions.

A right bundle branch block only occurs in medical conditions that affect the right side of the heart or lungs.

A left bundle branch block usually is a sign of an underlying heart disease, including dilated cardiomyopathy, hypertrophic cardiomyopathy, high blood pressure, aortic valve disease, coronary artery disease and other heart conditions. 

Diagnosing bundle branch block

A bundle branch block is usually diagnosed with an electrocardiogram.

Treating bundle branch block

Usually no treatment is needed for bundle branch block.

Get in touch

Dr. Richard Levy MD FACC FESC FRCP

0161 883 0366