1. Department of Surgery, University of Alabama at Birmingham, Alabama, USA
2. Kirklin Institute for Research in Surgical Outcomes and Division of Cardiothoracic Surgery, University of Alabama at Birmingham, Alabama, USA
3. Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, USA
4. Department of Surgery, School of Medicine and Public Health, University of Wisconsin at Madison, Madison, Wisconsin, USA
5. Dallas Veterans Affairs Hospital, University of Texas Southwestern, Dallas, Texas, USA