The nurse is caring for a client who has been taking milrinone for 3 months. Which clinical finding indicates the client is experiencing an adverse effect of the drug?

A. Hyperkalemia: Milrinone primarily affects cardiac contractility and vascular tone and does not typically cause hyperkalemia. Elevated potassium levels would more likely be related to other medications, renal dysfunction, or underlying conditions rather than milrinone therapy. B. Hypertension: Milrinone is a phosphodiesterase-3 inhibitor that causes vasodilation, which generally lowers blood pressure rather than increases it. Hypertension is not a common adverse effect of long-term milrinone use. C. Calf pain: Calf pain could indicate deep vein thrombosis or musculoskeletal issues, but it is not a recognized adverse effect of milrinone. While it should be assessed, it is unlikely related to the drug. D. Heart palpitations: Milrinone can cause arrhythmias, including palpitations, ventricular tachycardia, or atrial fibrillation, especially with long-term use. The presence of palpitations is a significant adverse effect and warrants immediate assessment and possible adjustment of therapy.