Which cardiac medication requires monitoring of serum potassium levels due to the risk of hyperkalemia?

A. Lisinopril: Lisinopril is an ACE inhibitor that reduces aldosterone secretion, leading to potassium retention. Clients taking this medication are at risk for hyperkalemia, so serum potassium levels must be closely monitored. B. Amlodipine: Amlodipine is a calcium channel blocker used for hypertension and angina. It primarily affects vascular smooth muscle and does not significantly influence potassium balance, so routine potassium monitoring is not required. C. Furosemide: Furosemide is a loop diuretic that increases urinary potassium excretion, which can cause hypokalemia. Monitoring potassium is important, but the risk here is deficiency rather than hyperkalemia. D. Digoxin: Digoxin does not directly alter potassium levels but its effects are influenced by potassium balance. Hypokalemia increases the risk of digoxin toxicity, making potassium monitoring important but not due to risk of hyperkalemia.