What is a bundle branch composed of?

Bundle branches are composed of specialized cardiac muscle cells known as Purkinje fibers. These fibers are larger in diameter and have fewer myofibrils than the regular myocardial cells of the heart. Purkinje fibers are responsible for the rapid conduction of electrical impulses from the atrioventricular node to the ventricles, ensuring the coordinated contraction of the heart chambers during each heartbeat.