2.3K views · 36 reactions | • 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 | Facebook