[1] Mayo Clin, Pediat & Congenital Echocardiog, Rochester, MN 55905 USA
[2] Mayo Clin, Coll Med, Dept Pediat, Rochester, MN 55905 USA
[3] Mayo Clin, Coll Med, Dept Cardiol, Rochester, MN 55905 USA
[4] Univ Washington, Med & Bioeth & Humanities, Seattle, WA USA