 Subjects who are scheduled to have planned apheresis treatment for severe hypercholesterolemia will be recruited into the study. They will undergo a screening evaluation, including a medical history, physical examination, ECG, and limited echocardiogram to evaluate for exclusion criteria. Before the apheresis procedure, blood samples will be obtained for plasma markers of inflammation, erythrocyte deformability, and plasma viscosity. Contrast enhanced ultrasound perfusion imaging will be performed to evaluate blood flow in the myocardium at rest, as well as in the forearm skeletal muscle before and after mild isometric exercise 50 maximal grip, 0.2 Hz. Flow mediated vasodilation will be performed. The subjects will then undergo their planned apheresis procedure. Within 2 hours of completion of apheresis, blood collection and CEU will be repeated. Plasma lipids will be available as part of the standard apharesis protocol. 