1. From the Department of Medicine, Division of Cardiology (R.H.H., M.B., S.K.D., R.T., H.R.H., R.D.B., D.A.K., A.C.L.), Department of Biomedical Engineering (P.A.H., H.R.H., R.D.B., D.A.K., A.C.L.), Department of Surgery (A.C.L.), and Department of Radiology (N.O., H.R.H., A.C.L.), Johns Hopkins University, Baltimore, Md.