1. Hannover Medical School; Hannover Germany
2. National Research Cardiac Surgery Center; Astana Kazakhstan
3. University of Vienna; Vienna Austria
4. German Heart Center; Berlin Germany
5. Heart Center Leipzig; Leipzig Germany
6. Peter Munk Cardiac Centre; Toronto General Hospital; Toronto Canada
7. Thoracic and Cardiovascular Surgery Clinic; Bad Oeynhausen Germany
8. University Heart Center Freiburg-Bad Krozingen, Medical Faculty; Albert Ludwigs-University; Freiburg Germany
9. The Alfred Hospital; Melbourne Australia
10. Abbott; Burlington MA USA
11. Institute for Clinical and Experimental Medicine; Prague Czech Republic