Left Bundle Branch Block: Understanding the Heart's Electrical Delay

Left bundle branch block (LBBB) is a type of heart rhythm disorder that affects the heart's electrical conduction system. In a normally functioning heart, the sinoatrial (SA) node serves as the primary pacemaker, initiating each heartbeat. Electrical signals from the SA node travel to the atrioventricular (AV) node, which is located between the atria and ventricles. From there, the signal splits into two pathways—the left and right bundle branches—both of which stimulate the heart's ventricles to contract in a synchronized manner.

How LBBB Affects Heart Function

When a person has left bundle branch block, the electrical signal cannot travel through the left bundle branch properly. As a result, the right ventricle receives the signal first and begins to contract before the left ventricle. This delay causes the two ventricles to beat out of sync, disrupting the heart's natural rhythm and efficiency.

Impact on Cardiac Performance

This lack of coordination between the ventricles can significantly reduce the heart's ability to pump blood effectively. Because the left ventricle—which is responsible for pumping oxygen-rich blood to the rest of the body—delays its contraction, the overall cardiac output decreases. Over time, this can lead to symptoms such as shortness of breath, fatigue, and in more severe cases, heart failure.

Understanding left bundle branch block is essential for diagnosing and managing heart-related conditions. While LBBB itself may not always require treatment, it often serves as an indicator of underlying heart disease that needs careful monitoring and care.