[1] Harbor UCLA Med Ctr, Dept Emergency Med, Torrance, CA 90502 USA
[2] Los Angeles Biomed Res Inst, Torrance, CA USA
[3] Univ Calif Davis, Med Ctr, Dept Pediat, Div Cardiol, Sacramento, CA 95817 USA
[4] Univ N Carolina, Dept Emergency Med, WakeMed Raleigh Campus, Raleigh, NC USA
[5] Duke Univ, Dept Pediat, Div Cardiol, Durham, NC 27706 USA