[1] Harvard Univ, Dept Cardiol, Sch Med, Childrens Hosp, Boston, MA 02115 USA
[2] Emory Univ, Dept Med, Atlanta, GA 30322 USA
[3] USN, Ctr Med, Dept Pediat, San Diego, CA USA
[4] Med Univ S Carolina, Dept Biostat Bioinformat & Epidemiol, Charleston, SC USA
[5] Med Univ S Carolina, Dept Pediat, Div Cardiol, Charleston, SC USA
[6] Med Univ S Carolina, Dept Surg, Div Cardiotherapy Surg, Charleston, SC USA