1. Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
2. Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
3. Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
4. Department of Cardiothoracic Surgery, Cairo University, Cairo, Egypt
5. Department of Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
6. Division of Cardiology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.