What type of electrical activity is associated with Idioventricular Rhythms?

The correct choice refers to the activity arising from the Purkinje fibers firing. Idioventricular rhythms, characterized by a rate usually between 20 and 40 beats per minute, occur when the normal pacemaker (the sinoatrial node) fails or is blocked, and the ventricles take over the pacing due to inherent automaticity of the Purkinje fibers.

This rhythm can manifest during situations such as severe bradycardia or after the loss of atrioventricular conduction. The action is typically due to the ventricles initiating depolarization, which results in a wide QRS complex on an ECG. The firing from the Purkinje fibers is essential in sustaining this rhythm when higher centers are not functioning appropriately.

In contrast, other choices pertain to different cardiac activities. Atrial activity alone, devoid of ventricular influence, would not account for the idioventricular rhythm. Ventricular tachycardia is a more rapid ventricular rhythm and presents distinctly from the slower idioventricular rhythm. Lastly, a sinus rhythm is regulated by the sinus node, indicating normal atrial activity, which is an entirely different mechanism from what is observed in idioventricular rhythms.