Bundle branches

Bundle branches are an essential part of the heart's electrical conduction system, which is responsible for coordinating the heartbeat. The bundle branches are pathways that transmit electrical impulses from the atrioventricular node (AV node) to the ventricles of the heart, ensuring that the heart beats in a synchronized manner.

Anatomy and Function

The bundle branches are divided into two main pathways:

• The right bundle branch
• The left bundle branch

Right Bundle Branch

The right bundle branch travels down the right side of the interventricular septum and transmits electrical impulses to the right ventricle. It ensures that the right ventricle contracts at the appropriate time during the cardiac cycle.

Left Bundle Branch

The left bundle branch splits into two further pathways known as the left anterior fascicle and the left posterior fascicle. These pathways transmit electrical impulses to the left ventricle, ensuring its timely contraction. The left bundle branch is responsible for the majority of the electrical conduction to the left ventricle.

Clinical Significance

Abnormalities in the bundle branches can lead to various cardiac arrhythmias and conduction disorders. Some of the common conditions include:

• Right bundle branch block (RBBB)
• Left bundle branch block (LBBB)

Right Bundle Branch Block (RBBB)

RBBB occurs when there is a delay or blockage in the right bundle branch, causing the right ventricle to contract later than the left ventricle. This can be detected on an electrocardiogram (ECG) by specific changes in the QRS complex.

Left Bundle Branch Block (LBBB)

LBBB occurs when there is a delay or blockage in the left bundle branch, causing the left ventricle to contract later than the right ventricle. This condition can also be identified on an ECG by characteristic changes in the QRS complex.

Diagnosis

The diagnosis of bundle branch blocks is primarily made using an electrocardiogram (ECG). The ECG will show specific patterns that indicate whether the right or left bundle branch is affected.

Treatment

Treatment for bundle branch blocks depends on the underlying cause and the presence of symptoms. In some cases, no treatment is necessary. However, if the bundle branch block is associated with other heart conditions or symptoms, treatment may include:

• Pacemaker implantation
• Medications to manage underlying heart disease

See Also

• Heart conduction system
• Atrioventricular node
• Purkinje fibers
• Electrocardiogram