What is bundle of His in cardiology?
The bundle of His, also known as the atrioventricular bundle, is a specialized group of cardiac muscle fibers that play a crucial role in the electrical conduction system of the heart. It is located in the interatrial septum, the wall that separates the left and right atria, and serves as the main electrical pathway between the atria and the ventricles, the chambers responsible for pumping blood.
The bundle of His is composed of several parts:
1. Atrioventricular node (AV node): The AV node is the first part of the bundle of His and acts as a delay station for electrical impulses traveling from the atria to the ventricles. This delay is essential to allow the atria to finish filling with blood before the ventricles contract.
2. Bundle of His: After leaving the AV node, the electrical impulse enters the bundle of His, which is a short, thick fiber bundle that continues the electrical pathway towards the ventricles.
3. Left and right bundle branches: The bundle of His divides into two main branches, the left bundle branch (LBB) and the right bundle branch (RBB). These branches carry the electrical impulse to the left and right ventricles, respectively, causing their coordinated contraction.
4. Purkinje fibers: The final portion of the conduction system is the Purkinje fibers. These are specialized cardiac muscle fibers that conduct the electrical impulse from the bundle branches throughout the ventricles, ensuring a rapid and uniform depolarization of the ventricular muscle, which leads to their forceful contraction.
The bundle of His and its branches are crucial for the proper electrical conduction and coordinated contraction of the heart. When the heart's electrical system functions correctly, the atria and ventricles contract in a synchronized manner with each heartbeat. However, damage to the bundle of His, such as from certain heart diseases, can lead to conduction abnormalities, including heart block, which disrupt the normal electrical pathway and cause disruptions in the heart's rhythm and function.
To diagnose heart rhythm problems related to the bundle of His, electrocardiography (ECG) and electrophysiology studies are commonly used. These tests measure the electrical activity of the heart and can detect abnormalities in the conduction pathway. Treatment options for bundle of His-related heart conditions may include medications, pacemaker implantation, or surgical interventions to restore normal heart rhythm.