1. From the Department of Cardiology, University Medical Center Utrecht (G.E.L., M.J.C., P.A.D.), Utrecht, the Netherlands; Departments of Physiology and Biomedical Engineering, Cardiovascular Research Institute Maastricht (J.L., T.D., F.W.P.), Maastricht, the Netherlands; Kantonsspital Luzern (B.W.L.D.B.), Luzern, Switzerland.