1. From the Clinical Physiology (R.J., H.E., H.A., E.H., M.C.) and Cardiology (U.C., J.v.d.P., R.B.), Department of Clinical Sciences, Lund University, Lund University Hospital, Sweden; Department of Biomedical Engineering and Centre for Mathematical Sciences, Faculty of Engineering, Lund University, Sweden (E.H.); and Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD (K.C.W.).