What role does the AV node play when AFib occurs?

In atrial fibrillation (AFib), the atria experience chaotic electrical activity, which leads to rapid and irregular heartbeats. The AV node, or atrioventricular node, plays a crucial role as it acts as a gatekeeper between the atria and the ventricles. When the electrical signals from the atria are disorganized, the AV node helps control the number of impulses that reach the ventricles.

Though the SA node typically initiates the heartbeat, during AFib the atrial activity is so erratic that the AV node becomes necessary to maintain some level of coordination. The AV node acts as a secondary pacemaker by slowing down the conduction of these impulses, thereby preventing the ventricles from contracting too quickly and maintaining a more organized rhythm. This function is essential in preventing excessively rapid ventricular rates that can be hemodynamically unstable and lead to complications.

This role of the AV node highlights its importance in managing the effects of AFib, as it helps provide a semblance of order to the heart's contractions, even when the atrial rhythm is abnormal.