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