1. From the Department of Medicine, Division of Cardiology (A.R., M.M.Z., G.R.M., T.M.D., A.L., R.D.B., H.C.), and Departments of Pathology (E.R.R.), Radiology (D.A.B., H.R.H.), and Biomedical Engineering (H.R.H.), Johns Hopkins Medical Institutions, Baltimore, Md.