1. Division of Cardiovascular Medicine and the Vanderbilt Pulmonary Circulation Center, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee;
2. Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina;
3. Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland; and
4. Institute for Health Computing, University of Maryland, Bethesda, Maryland