1 Department of Pediatrics, Section of Pediatric Cardiology, University of Arkansas for Medical Sciences, 1 Children's Way, Slot 512-3, Little Rock, AR 72202-3591. Electronic address: ehbolin@uams.edu.
2 Department of Epidemiology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
3 Department of Pediatrics, Section of Pediatric Cardiology, Stanford University School of Medicine, Palo Alto, California.