Heart block is a condition in which the electrical signals that control the heartbeat are delayed or completely blocked as they travel through the heart. This disruption occurs in the heart’s conduction system, primarily at the atrioventricular (AV) node or the bundle branches. Heart block is classified into three degrees: **first-degree**, where electrical impulses slow down but still reach the ventricles; **second-degree**, where some signals fail to reach the ventricles, causing irregular hea

• Sinoatrial Exit Block • Sino-atrial exit block is due to failed propagation of pacemaker impulses beyond the SA node. • The sino-atrial node continues to depolarise normally. • However, some of the sinus impulses are “blocked” before they can leave the SA node, leading to intermittent failure of atrial depolarisation (dropped P waves). | Manual of Medicine