[1] Univ Penn, Childrens Hosp Philadelphia, Cardiac Ctr, Sch Med, Philadelphia, PA 19104 USA
[2] Emory Univ, Sch Med, Childrens Healthcare Atlanta, Atlanta, GA 30322 USA
[3] Univ Cincinnati, Childrens Hosp Med Ctr, Coll Med, Heart Inst, Cincinnati, OH 45221 USA
[4] Texas Childrens Hosp, Baylor Coll Med, Lillie Frank Abercrombie Sect Cardiol, Houston, TX 77030 USA