1. From the Centre for Advanced Visualisation and Interaction (T.S.S.) and the Department of Computer Science (J.M.), University of Aarhus, Aarhus, Denmark; Departments of Cardiology (G.F.G., L.S.) and Radiology (S.M., A.S.), Tübingen University Hospital, Tübingen, Germany; and Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark (O.K.H.).