What is the difference between RBBB and LBBB?

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The heart requires an electrical impulse to beat. This electrical current is generated in the sinoatrial (SA) node, which acts like an electric generator. The current travels through the bundle branches, similar to wires, to conduct the impulse throughout the heart. It first moves from the SA node to the atrioventricular (AV) node via the atrial bundles. From the AV node, the impulse is transmitted to a small bundle called the His bundle. It then travels to the right ventricle through the right bundle branch and to the left ventricle via the left bundle branch. The impulse further divides as it reaches the ventricles.

If there is an interruption in the right bundle branch, this is called a right bundle branch block (RBBB), and the same can occur for the left bundle branch, known as the left bundle branch block (LBBB). A right bundle branch block is often not as dangerous because the right ventricle is a low-pressure chamber, that pumps blood to the lungs, which also have low pressure. In contrast, the left ventricle pumps blood to the entire body and needs to generate more force.

When an LBBB occurs, the left ventricle is activated by the current coming from the right bundle branch, there is a slight delay—only milliseconds, but it is significant. This delay causes dysynchrony between the ventricles, which may result in ineffective output from the left ventricle. Since the vascular system is interconnected, the heart must work in a rhythmic, synchronized way for optimal function.

Furthermore, LBBB often occurs as a result of a heart attack. However, this process is much more complex than described here. It takes time to fully understand the heart’s intricate workings and connections. I hope this explanation gives you a basic understanding of LBBB and RBBB.

I hope this helps you.

Thank you.