1. Division of Cardiology, Duke University Medical Center, Durham, North Carolina
2. Duke Clinical Research Institute, Durham, North Carolina
3. Society of Thoracic Surgeons Research Center, Chicago, Illinois
4. Department of Cardiac Surgery, Medstar Heart and Vascular Institute, Georgetown University, Washington, District of Columbia
5. Division of Cardiothoracic Surgery, University of Pennsylvania, Philadelphia
6. Department of Cardiovascular and Thoracic Surgery, West Virginia University, Morgantown