. Author manuscript; available in PMC: 2015 Feb 1.
Published in final edited form as: J Am Soc Echocardiogr. 2013 Dec 4;27(2):192–199. doi: 10.1016/j.echo.2013.10.011
© 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.