Ventricular fibrillation is described as what type of arrhythmia?

Ventricular fibrillation is described as a type of arrhythmia where the heart muscles quiver ineffectively instead of contracting in an organized manner that allows for proper blood circulation. This chaotic electrical activity prevents the ventricles from filling and emptying effectively, leading to a cessation of effective blood flow to the body's organs. In this state, the heart cannot pump blood, which is critical for maintaining oxygen delivery, and if not corrected promptly, it can lead to cardiac arrest.

The other options do not accurately capture the nature of ventricular fibrillation. Infrequent heartbeats refer to bradycardia or other arrhythmias where the heart beats less than normal, while a racing heart rate refers to tachycardia, which is characterized by a heart rate over 100 beats per minute but does not specify the chaotic rhythm seen in fibrillation. Similarly, regular but weak heartbeats suggest a more controlled rhythm despite being weak, which contrasts sharply with the complete lack of organized electrical activity in ventricular fibrillation. Thus, the description of the heart quivering instead of pumping blood is the most accurate portrayal of this life-threatening arrhythmia.