RT Journal Article SR Electronic T1 Improved detection of protruding apical thrombus with contrast echocardiography JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 1297 OP 1297 DO 10.1136/heart.89.11.1297 VO 89 IS 11 A1 P Rerkpattanapipat A1 C Brown A1 D W Kitzman YR 2003 UL http://heart.bmj.com/content/89/11/1297.abstract AB