Which option best identifies the electrolyte most commonly linked to dangerous cardiac arrhythmias?

• A. Hypercalcemia
• B. Hyperkalemia
• C. Hypophosphatemia
• D. Hypernatremia

Answer: (B)

Potassium balance has the strongest influence on how the heart conducts electricity. Among electrolyte disturbances, too much potassium directly poses the greatest danger for dangerous arrhythmias. When serum potassium rises, the extracellular gradient across cardiac cell membranes is reduced, making the resting membrane potential less negative. This initially alters excitability and, as levels climb, slows conduction and widens the QRS, paving the way for life‑threatening rhythms. Classic ECG changes include peaked T waves early, progressing to QRS widening and, at very high levels, a sine-wave pattern that can degenerate into ventricular fibrillation or asystole if not treated promptly. While other electrolyte abnormalities can affect rhythm, hyperkalemia is most consistently linked to dangerous arrhythmias because of its direct and profound effect on cardiac electrical activity.