I44: Atrioventricular and left bundle-branch block

Atrioventricular and left bundle-branch block refers to types of heart block, where there is a delay or a block in the electrical signals that control the rhythm of the heart. The atrioventricular (AV) block is categorized into three types. In the first type, there is a minor slowdown in the signal transmission from the upper to the lower chambers of the heart. In the second type, not all signals reach the lower chambers. In the third and most severe type, the signals don’t pass through at all. On the other hand, left bundle-branch block means that the electrical impulses are slowed or blocked when they move through the left branch of the bundle of His, a pathway that carries these signals. Both conditions interrupt the steady, regular rhythm of the heart, potentially causing symptoms such as fatigue, lightheadedness, shortness of breath, and chest pain. These blocks are most commonly due to damage from heart disease, high blood pressure, or heart attack.