A 35-year-old female complains of slowly progressive dyspnea. Her history is otherwise unremarkable, and there is no cough, sputum production, pleuritic chest pain, or thrombophlebitis. She has taken appetite suppressants at different times. On physical exam, there is jugular venous distention, a palpable right ventricular lift, and a loud P2 hea sound. Chest x-ray shows clear lung fields. ECG shows right axis detion. A perfusion lung scan is normal with no segmental deficits. The most likely diagnosis in this patient is

(Braunwald, 15/e, pp 1506-1508.) Although a difficult diagnosis to make, primary pulmonary hypeension is the most likely diagnosis in this young woman who has used appetite suppressants. There has been a recent increase in primary pulmonary hypeension in the individuals consuming fenfluramines, an appetite suppressant. The predominant symptom is dyspnea, which is usually not apparent in the previously healthy young woman until the disease has advanced. When signs of pulmonary hypeension are apparent from physical findings, chest x-ray, or echocardiography, the diagnosis of recurrent pulmonary embolus must be ruled out. In this case, a normal perfusion lung scan makes pulmonary angiography unnecessary. Restrictive lung disease should be ruled out with pulmonary function testing. An echocardiogram will show right ventricular enlargement and a reduction in the left ventricle size consistent with right ventricular pressure overload.