1. Department of Cardiac Surgery Heart Center at Missouri Baptist Medical Center St. Louis Missouri USA
2. Department of Cardiac Surgery University Medical Center Ljubljana Slovenia
3. Department of Cardiac Surgery Istituto Clinico Sant'Ambrogio Milano Italy
4. Department of Cardiovascular and Thoracic Surgery West Virginia University Heart and Vascular Institute Morgantown West Virginia USA
5. Department of Cardiac Surgery Franciscan St. Francis Heart Center Indianapolis Indiana USA
6. Department of Cardiac Surgery Klinikum Nürnberg Cardiovascular Center, Paracelsus Medical University Nuremberg Germany