What frequency of firing do multiple automaticity foci display in ventricular fibrillation?

What frequency of firing do multiple automaticity foci display in ventricular fibrillation?

• A. 200-250 bpm
• B. 250-350 bpm
• C. 350-450 bpm
• D. 450-600 bpm

Answer: (B)

In ventricular fibrillation, multiple automaticity foci are firing at a high frequency due to chaotic electrical activity in the ventricles. This disorganized electrical activity leads to ineffective contractions and a lack of coordinated heartbeat. The typical frequency of firing for multiple automaticity foci in this condition is characterized by rates between 250 to 350 beats per minute. This high frequency indicates a rapid and chaotic rhythm that prevents the heart from effectively pumping blood.

Understanding the ranges provided helps clarify why this frequency is crucial in diagnosing and managing ventricular fibrillation. Frequencies below 250 bpm would indicate a less chaotic rhythm, while rates above 350 bpm, such as those in the ranges of 350-450 bpm or even 450-600 bpm, would imply an extremely rapid and unstable electrical activity that is less typical for ventricular fibrillation. The correct range effectively captures the expected behavior of automaticity foci during this arrhythmia, reinforcing the need for immediate medical intervention in such situations.