[1] Fetal Diagnost Ctr Pasadena, Pasadena, CA 91105 USA
[2] GE Med Syst Kretz Ultrasound, Zipf, Austria
[3] Univ So Calif, Keck Sch Med, Childrens Hosp Los Angeles, Dept Pediat,Div Pediat Cardiol, Los Angeles, CA USA
[4] Ctr Fetal Med & Womens Ultrasound, Los Angeles, CA USA