. Author manuscript; available in PMC: 2014 Oct 24.
Published in final edited form as: J Am Soc Echocardiogr. 2013 Mar 26;26(5):521–529. doi: 10.1016/j.echo.2013.02.012
© 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.