title: Magnetic resonance image-guided transcatheter closure of atrial septal defects.
abstract: BACKGROUND
  Recent developments in cardiac MRI have extended the potential spectrum of diagnostic and interventional applications. The purpose of this study was to test the ability of MRI to perform transcatheter closures of secundum type atrial septal defects (ASD) and to assess ASD size and changes in right cardiac chamber volumes in the same investigation.
  
  
  RESULTS
  In 7 domestic swine (body weight, 38+/-13 kg), an ASD (Q(p):Q(s)=1.7+/-0.2) was created percutaneously by balloon dilation of the fossa ovalis. The ASD was imaged and sized by both conventional radiography and MRI. High-resolution MRI of the ASD diameters correlated well with postmortem examination (r=0.97). Under real-time MR fluoroscopy, the introducer sheath was tracked toward the left atrium with the use of novel miniature MR guide wires. The defect was then closed with an Amplatzer Septal Occluder. In all animals, it was possible to track and interactively control the position of the guide wire within the vessels and the heart, including the successful deployment of the Amplatzer Septal Occluder. Right atrial and ventricular volumes were calculated before and after the intervention by using cine-MRI. Both volumes were found to be significantly reduced after ASD closure (P<0.005).
  
  
  CONCLUSIONS
  These in vivo studies demonstrate that catheter tracking and ASD device closure can be performed under real-time MRI guidance with the use of intravascular antenna guide wires. High-resolution imaging allows accurate determination of ASD size before the intervention, and immediate treatment effects such as changes in right cardiac volumes can also be measured.
authors.affiliation: University of Minnesota, Department of Radiology, Minneapolis, Minn, USA.
authors.forename: Carsten
authors.initials: C
authors.lastname: Rickers
authors.forename: Michael
authors.initials: M
authors.lastname: Jerosch-Herold
authors.forename: Xudong
authors.initials: X
authors.lastname: Hu
authors.forename: Naveen
authors.initials: N
authors.lastname: Murthy
authors.forename: Xiaoen
authors.initials: X
authors.lastname: Wang
authors.forename: Huafu
authors.initials: H
authors.lastname: Kong
authors.forename: Ravi Teja
authors.initials: RT
authors.lastname: Seethamraju
authors.forename: Jochen
authors.initials: J
authors.lastname: Weil
authors.forename: Norbert M
authors.initials: NM
authors.lastname: Wilke
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization / Q000295:instrumentation*; D002306:Cardiac Volume; D005471:Fluoroscopy; D006321:Heart / Q000503:physiopathology; D006344:Heart Septal Defects, Atrial / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D006439:Hemodynamics; D008279:Magnetic Resonance Imaging; D012680:Sensitivity and Specificity; D013552:Swine