Which of the following is a known cause of ventricular fibrillation?

• A. Hypoglycemia
• B. Myocardial ischemia or infarction
• C. Hyperglycemia
• D. Hypertension

Answer: (B)

Ventricular fibrillation is driven by rapid, disorganized electrical activity in the ventricles due to acute electrical instability of the heart muscle. The most well-established trigger for this chaos is acute myocardial ischemia or infarction. When heart tissue becomes ischemic, its cells lose ATP, ion pumps fail, and potassium and calcium handling becomes deranged. This creates multiple ectopic electrical foci and promotes reentry circuits, so the ventricles fire in a chaotic, uncoordinated way rather than contracting effectively. The result is no meaningful cardiac output and sudden deterioration unless defibrillation rapidly restores organized rhythm.

Other conditions listed do not typically precipitate VF in the same direct, immediate way. Metabolic derangements like hypoglycemia or hyperglycemia affect overall physiology and can influence arrhythmia risk in certain contexts, but they are not classic, direct triggers of ventricular fibrillation. Hypertension over time can contribute to structural heart changes that raise arrhythmia risk, but it is not the immediate precipitant of VF as seen with acute ischemia or infarction.