Which of the following indicates a complete failure of the SA and AV nodes?

A complete failure of the SA (sinoatrial) and AV (atrioventricular) nodes leads to an idioventricular rhythm. This rhythm originates from the ventricles when the heart's normal pacemaking functions are disrupted, resulting in no impulses being generated by the SA and AV nodes. In such cases, the ventricles take over as the primary pacemaker at a much slower rate, typically between 20-40 beats per minute.

This situation is characterized by wide QRS complexes and a lack of P waves, indicating that the heart is no longer being controlled by the typical conduction system. The idioventricular rhythm serves as a vital safety mechanism, allowing the heart to pump blood even in the absence of higher control from the atria or nodes. Understanding this mechanism is crucial in recognizing critical cardiac situations and implementing appropriate interventions.