1. Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA.
2. Division of Cardiology, Department of Medicine, University of Missouri, Kansas City, MO.
3. Saint Luke's Mid-America Heart Institute, Kansas City, MO.
4. Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA.
5. Division of Cardiovascular Medicine, University of Texas Southwestern Medical Center, Dallas, TX.