In a client with a history of heart failure, taking which medication requires additional monitoring for potassium levels?

The choice of ACE inhibitors as the medication requiring additional monitoring for potassium levels in a client with a history of heart failure is based on how these medications affect electrolyte balance in the body. ACE inhibitors work by inhibiting the angiotensin-converting enzyme, which leads to a decrease in the production of angiotensin II, a hormone that narrows blood vessels and increases blood pressure. This action not only lowers blood pressure and helps with heart failure management but can also affect kidney function.

One significant effect of ACE inhibitors is their potential to cause hyperkalemia, which is an elevated level of potassium in the blood. This occurs because ACE inhibitors can impair aldosterone production, a hormone responsible for promoting the excretion of potassium in the urine. When aldosterone levels are reduced, the body retains more potassium, necessitating careful monitoring of serum potassium levels to prevent complications associated with hyperkalemia, such as cardiac arrhythmias.

For the other medications listed, while monitoring might be necessary for other reasons, they do not typically have the same significant effect on potassium levels in heart failure patients as ACE inhibitors. For example, beta blockers are mainly concerned with heart rate and contractility, while calcium channel blockers primarily affect vascular smooth muscle and can have other side effects.