RWTH Aachen, Germany
Dep. of Cardiothoracic Surgery, Hadassah University, Jerusalem, Israel (1998-1999)
Dep. of Cardiothoracic Surgery, University of Cologne, Germany (1999-2001)
Dep. of Cardiovascular & Thoracic Surgery, Herzzentrum NRW Bad Oeynhausen, Germany (2001- )