1. From the Centers for Cardiovascular Bioinformatics & Modeling (P.A.H., R.L.W.) and Imaging Science (L.Y., M.I.M.) and Division of Cardiology (C.L., D.K.), Johns Hopkins University, Baltimore, Md; Engineering Science (M.F.B.), Simon Fraser University, Burnaby, British Columbia, Canada; and Laboratory of Cardiac Energetics (D.B.E., O.P.F., E.M.), National Heart Lung Blood Institute, National Institutes of Health, Bethesda, Md.