What causes ventricular fibrillation?

What causes ventricular fibrillation?

• A. Single automaticity focus in the ventricles
• B. Multiple irritable automaticity foci in the ventricles
• C. High serum potassium levels
• D. Coronary artery disease

Answer: (B)

Ventricular fibrillation occurs due to the presence of multiple irritable automaticity foci in the ventricles. This condition leads to erratic electrical activity as several areas within the ventricle become hyperexcitable and start firing spontaneously. The disorganized electrical impulses prevent the heart from effectively contracting and pumping blood, resulting in a life-threatening situation where effective circulation ceases.

When there are multiple foci firing at different rates, the normal coordinated contraction of the heart is disrupted, leading to a chaotic quivering of the ventricles instead of a proper heartbeat. This mechanism explains why the presence of multiple irritable foci is a significant risk factor for the onset of ventricular fibrillation.

Other conditions, such as high serum potassium levels and coronary artery disease, can contribute to the risk of developing ventricular fibrillation but do not directly lead to it through the same mechanism of multiple firing foci. Understanding this relationship is crucial for recognizing how ventricular fibrillation can arise in various clinical settings.