[1] Stanford Univ, Sch Med, Dept Pediat Cardiol, Palo Alto, CA 94304 USA
[2] Univ Alabama, Birmingham, AL USA
[3] Feinberg NW Sch Med, Chicago, IL USA
[4] Loma Linda Univ, Med Ctr, Loma Linda, CA 92350 USA
[5] Childrens Hosp Pittsburgh, Pittsburgh, PA 15213 USA