1. Friedrich-Ebert Hospital, Neumünster, Germany.
2. Ospedale Loreto Mare, Naples, Italy.
3. Onassis Cardiac Center, Athens, Greece.
4. Hôpital Pitié-Salpêtrière, Paris, France.
5. St. Jude Medical, Zaventem, Belgium.
6. St. Jude Medical, Eschborn, Germany.
7. Dept. of Heart and Vessels, University of Florence, Cliniche Gavazzeni, Bergamo, Italy.