1. Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD (C.G.B., J.M.K., T.R., D.K.Y., R.J.L.).
2. MedStar Washington Hospital Center, Washington, DC (T.R.).
3. Structural Heart and Valve Center, Emory University Hospital, Atlanta, GA (V.C.B., A.B.G.).