RT Journal Article SR Electronic T1 Non-invasive follow up of an atrial septal defect device occlusion JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 464 OP 464 DO 10.1136/hrt.2004.041665 VO 91 IS 4 A1 C Lilje A1 F Weiss A1 J Weil YR 2005 UL http://heart.bmj.com/content/91/4/464.abstract AB