1 Division of Cardiovascular Surgery, Department of Surgery, University of Pennsylvania, Philadelphia, Pa.
2 Division of Thoracic Surgery, The Johns Hopkins Medical Institutions, Baltimore, Md.
3 Division of Cardiac Surgery, Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Ill.
4 Division of Cardiothoracic Surgery, University of Cincinnati Medical Center, Cincinnati, Ohio.
5 Division of Cardiac Surgery, Department of Surgery, Yale University School of Medicine, New Haven, Conn.
6 Division of Cardiac Surgery, Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pa.
7 Division of Cardiothoracic Surgery, Department of Cardiothoracic Surgery, University of Texas Health Science Center at San Antonio, San Antonio, Tex.
8 Division of Cardiothoracic Surgery, Department of Surgery, The Brigham and Women's Hospital, Boston, Mass.
9 Division of Cardiothoracic Surgery, Department of Surgery, Indiana University, Boston, Mass.
10 Division of Cardiothoracic Surgery, Department of Surgery, University of Rochester, Rochester, NY.