What is the primary mechanism behind cardioversion for atrial fibrillation?

Cardioversion, especially in the context of atrial fibrillation, involves delivering a synchronized electrical shock to the heart to restore a normal rhythm. The primary mechanism is related specifically to timing: the shock must be delivered at the right moment during the cardiac cycle, particularly during the R wave of the QRS complex, to avoid causing further complications, such as ventricular fibrillation. This precise timing ensures that the shock can effectively disrupt the chaotic electrical activity of the atria and allow the sinus node to regain control over the heart's rhythm.

In contrast, increasing heart rate is not the goal of cardioversion, nor is it used to diagnose the type of atrial fibrillation. While cardioversion can convert atrial fibrillation into a normal rhythm, its purpose is not to provide a permanent correction for the arrhythmia. In fact, many patients may experience recurrences of atrial fibrillation even after successful cardioversion, necessitating additional treatments. Thus, the correct focus of cardioversion hinges on the delivery of the shock at the appropriate time to effectively restore normal atrial activity.