Microvascular and Cardiac Dysfunction in Paroxysmal Nocturnal Hemoglobinuria and Sickle Cell Disease

The purpose of this study is to examine how abnormal blood flow in the small vessels (microvessels) of the heart, muscle and kidney in paroxysmal nocturnal hemoglobinuria (PNH) or sickle cell disease leads to poor functioning of the heart and kidney. To test this question, the investigators will perform imaging tests (contrast ultrasound perfusion imaging) to look at the flow and function of these microvessels and compare this information to heart and kidney function. To further look at this question, patients who have PNH will be studied before and after starting a new drug (Soliris) that decreases damage to blood cells. In patients with sickle cell disease, patients will be studied at baseline (not during a pain crisis) and also during a pain crisis if one develops.