1. Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine and Abboud Cardiovascular Research Center, University of Iowa, 100 Newton Road, 1191D ML, Iowa City, IA, USA
2. Division of Cardiology, Department of Medicine, UPMC Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, USA
3. Cardiology Section, Medical Service, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, William. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
4. Department of Radiology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
5. Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA