. Author manuscript; available in PMC: 2014 Mar 1.
Published in final edited form as: J Am Soc Echocardiogr. 2013 Jan 11;26(3):290–296. doi: 10.1016/j.echo.2012.12.008
© 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.