A 41-year-old male schoolteacher, a nonsmoker, presents with lightheadedness and increased shoness of breath with "lack of stamina" and chest pain. On physical examination, vital signs are normal. The patient is overweight with a BMI of 33. CVS exam reveals a left parasternal heave with a harsh grade 3/6 systolic flow murmur and a loud P2 sound. Chest radiographs are shown below.What is the most likely diagnosis?

The PA view shows bilateral hilar fullness with well-defined soft tissue opacities. These opacities taper caudally. The aoa is normal, there is no paratracheal lymphadenopathy, and the concavity of the aoopulmonary window is maintained. The symptoms described in this patient and the characteristic CXR are consistent with pulmonary hypeension. This could be fuher worked up and confirmed by an echocardiogram to estimate PA pressures. Chronic bronchitis is unlikely in this nonsmoker, and deconditioning would not give the physical signs observed. There is no clinical or radiographic evidence of mitral stenosis. PFT and exercise test would be abnormal but nonspecific, and aggressive exercise programs would be contraindicated.