A 27-year-old woman is admitted with cough, shoness of breath, and palpitations. She has been relatively well for most of her life, but her mother gives a history that the patient had recurrent "pneumonia" as a child. The patient denies any sputum production. On examination, she appears anxious. Her neck veins are distended and she has a widened split second hea sound with little respiratory variation. A systolic ejection murmur in the pulmonic area is noted. Lung exam reveals bilateral crackles; mild ascites and pedal edema are also noted. EKG shows right axis detion. CXR is shown in.. The next diagnostic step is

The cardiac silhouette is normal in size, but the pulmonary vasculature is prominent and the AP window is full. The interlobar branches appear large. There is pulmonary plethora with increased vasculature, especially in the right lower zone and the left upper zone, with increase in size of the aerial shadows suggesting increased pulmonary blood flow The clinical syndrome described best fits the diagnosis of atrial septal defect with secondary pulmonary hypeension. The chest radiograph is consistent with pulmonary hypeension. Other options are inappropriate. The next diagnostic step would be to do an echocardiogram.