Which electrolyte disturbance is most commonly associated with dangerous ventricular arrhythmias and should be corrected promptly?

• A. Hyperkalemia
• B. Hypokalemia
• C. Hypomagnesemia
• D. Hypermagnesemia

Answer: (A)

Potassium balance directly controls how excitable and conductive the heart is. When potassium is elevated outside cells, the resting membrane potential becomes less negative, which slows myocardial repolarization and conduction. The result is a progression from characteristic ECG changes to widening QRS complexes and eventually dangerous ventricular rhythms such as ventricular tachycardia or fibrillation, potentially leading to cardiac arrest if not corrected promptly. That immediacy makes hyperkalemia the electrolyte disturbance most commonly associated with dangerous ventricular arrhythmias and requires rapid treatment to stabilize the myocardium, shift potassium back into cells, and remove excess potassium from the body. While hypokalemia and hypomagnesemia can predispose to arrhythmias in other contexts, the situation described emphasizes the urgent risk from hyperkalemia.