A 62-year-old man presents to the office for assessment of symptoms of shortness of breath. The symptoms are worse with exertion and he notes difficulty lying down. He reports no chest pain or palpitations but his feet are swollen. His past medical history includes hypertension and type 2 diabetes, for which he is taking ramipril, amlodipine, and metformin.On physical examination, the blood pressure is 125/84 mm Hg, heart rate is 100/min. The jugular venous pressure is 8 cm above the sternal angle, with a third heart sound, pedal edema, and bibasilar crackles on auscultation of the lungs. Which one of the following may be implicated in fluid retention for this condition?