what is a bundle block of the heart
Bundle branch block A bundle branch block is a defect of the bundle branches or fascicles in the electrical conduction system of the heart.
Cardiac pacemaker If the SA node does not function properly and is unable to control the heart rate, a group of cells further down the heart will become the ectopic pacemaker of the heart. These cells form the atrioventricular node (or AV node), which is an area between the left atrium and the right ventricle within the atrial septum, will take over the pacemaker responsibility.