1. Department of Vascular Surgery and Ludwig Boltzmann Institute of Cardiosurgical Research, University of Vienna School of Medicine, Vienna, Austria
2. Department of Cardiothoracic Surgery and Ludwig Boltzmann Institute of Cardiosurgical Research, University of Vienna School of Medicine, Vienna, Austria
3. Institute of Mathematics, Technical University, Graz, Graz, Austria
4. Institute of Medical Informatics, Statistics and Documentation, University of Graz, Graz, Austria