[1] Kaiser Permanente Med Ctr, Dept Pediat, Los Angeles, CA 90027 USA
[2] Childrens Hosp Los Angeles, Div Pediat Cardiol, Los Angeles, CA 90027 USA
[3] Childrens Hosp Los Angeles, Div Cardiothorac Surg, Los Angeles, CA 90027 USA
[4] Univ Calif Los Angeles, Harbor Med Ctr, Torrance, CA 90509 USA
[5] Univ Verona, Div Cardiac Surg, I-37100 Verona, Italy