A client with congestive heart failure complains of feeling fatigued and weak after mild physical activity, such as getting dressed or walking short distances. The nurse should identify this symptom as:

A) This choice is incorrect because hypokalemia (low potassium levels) is more commonly associated with loop diuretics rather than beta-blockers.

B) This choice is incorrect because while hypotension (low blood pressure) can be a potential adverse effect of beta-blockers, it is not the primary adverse effect to be monitored for.

C) This choice is correct. Bradycardia (slow heart rate) is a common adverse effect of beta-blockers, which work by slowing the heart rate and reducing the force of the heart's contractions. The nurse should monitor the client's heart rate and report any significant changes or symptoms of bradycardia to the healthcare provider.

D) This choice is incorrect because hyperglycemia (high blood glucose levels) is not a common adverse effect of beta-blockers. In fact, beta-blockers can sometimes cause transient hypoglycemia.

A) This choice is incorrect because a narrowed mediastinum is not a characteristic finding in congestive heart failure. The mediastinum is the central region of the chest, and its width is not specifically related to CHF.

B) This choice is incorrect because hyperinflated lungs are a characteristic finding in chronic obstructive pulmonary disease (COPD), not congestive heart failure.

C) This choice is correct. Cardiomegaly, an enlarged heart, is a common finding in congestive heart failure. The heart may appear enlarged on a chest X-ray due to fluid accumulation and strain on the heart muscle.

D) This choice is incorrect because a normal cardiac silhouette on a chest X-ray would not be indicative of congestive heart failure. The presence of cardiomegaly is more suggestive of heart failure.