Sildenafil to Improve Exercise Capacity in People With Thalassemia and Pulmonary Hypertension

Thalassemia is an inherited blood disorder that can result in mild to severe anemia. Many people with thalassemia also have pulmonary hypertension, which is high blood pressure in the arteries in the lungs. This study will evaluate the safety and effectiveness of the medication sildenafil at reducing blood pressure in the lungs of people with thalassemia and pulmonary hypertension.