1. Department of Thoracic and Cardiovascular Surgery, West-German Heart and Vascular Center Essen, University Hospital Essen, Essen, Germany;
2. Chair of Mechanics and Robotics, University Duisburg-Essen, Duisburg, Germany;
3. Institute for Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany