1. Division of Cardiology, University of Maryland Medical Center, Baltimore, MD USA
2. Thoracic and Cardiovascular Surgery, the Cleveland Clinic, Cleveland, OH USA
3. Cardiac Surgery, Swedish Heart & Vascular Institute, Seattle, WA USA
4. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, MD USA
5. Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.