. Author manuscript; available in PMC: 2012 Jul 1.
Published in final edited form as: J Am Soc Echocardiogr. 2011 Apr 20;24(7):808–814. doi: 10.1016/j.echo.2011.03.003
© 2011 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.