In order to truly understand the concept of right bundle branch block, you will have to understand a few things about bundle branches. Our heart has an electrical pathway which is required to send electrical impulses to the heart’s ventricles. A component of this electrical pathway is the bundle branch. The branch actually divides into two namely the right bundle branch and the left bundle branch. The task of the bundles is to deliver the electrical impulses to the ventricles in order to contract them.

What Is Right Bundle Branch Block?

The condition which causes either a hindrance or a delay along the electrical pathway is named the bundle branch block. This condition eventually results in irregular heartbeats. With bundle branch block, the electrical impulses are delivered by the left and right bundle branches at the same time with the same speed. However, when a block develops in either one of them, the electrical impulses have to take a slightly different path and this affects their speed. As a result, one impulse reaches one ventricle early while the other impulse reaches the other ventricle fractionally later. This results in irregular beating of the heart.

Right bundle branch block, also known as RBBB, is the condition in which the conduction system of the heart doesn’t work properly. In RBBB, the right ventricle of the heart can’t get activated through impulses that travel from the right bundle branch. The left bundle branch delivers electrical impulses as required to activate the left ventricle. In order to activate the right ventricle in such a condition, the impulses travel from the left ventricle’s myocardium to the heart’s right ventricle. This is how right ventricle gets activated during RBBB.

What Causes Right Bundle Branch Block?

Bundle branch block of either kind whether it be the right bundle branch block or the left bundle branch block can prove dangerous. There can be a wide variety of causes behind RBBB. They include:

  • A congenital heart defect like the atrial septal defect (the name given to the hole in that wall which separates the heart’s upper chambers)

  • Minor or major heart attack

  • A heart muscle infection either viral or bacterial

  • Very high blood pressure

  • Blockage in an artery of the lung, medically called a pulmonary embolism

How to Diagnose Right Bundle Branch Block

The test that can diagnose an issue like bundle branch block is electrocardiogram. The electrocardiogram forms a record of your heart’s electrical impulses with the help of wires that are attached to your skin in and around the chest as well as other body parts during the testing. Any irregularity can point out the presence of not just bundle branch block but also whether it is right or left bundle branch block.

In order to categorize the bundle block on the electrocardiogram as RBBB, the test should show the following:

  • The rhythm of the heart must initiate at sinoatrial or atrioventricular node (on top of the ventricles) for the activation of the conduction system at the right time.

  • The duration or width of QRS (three graphical deflections on an electrocardiogram) must be over 100ms for an incomplete block and must be over 120 ms for a complete block.


A Q wave is the first downward deflection of the complex.

An R wave is the first upward deflection of the complex. A noticeable terminal R wave should be present in lead V1 (like qR, rSR, R, rsR)

S waves refer to any downward deflection after an R wave. A noticeable indistinct S wave should be present in lead V6 and in lead I.

The deflection of QRS complex should be opposite to that of the T wave. This discordance confirms bundle branch block. You can click HERE to get better understanding of diagnosing of RBBB with pictures.

A Word About Treating Right Bundle Branch Block

Majority of the people suffering from the condition have no symptoms and require no treatment. Treatment is only required in case the right or left branch block is being caused by an underlying heart disease. These treatments might include medicines to lower high blood pressure or a small surgery like coronary angioplasty that would open the artery that leads to your heart.


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