title: Real-time MR imaging-guided laser atrial septal puncture in swine.
abstract: OBJECTIVE
  The authors performed this study to report their initial preclinical experience with real-time magnetic resonance (MR) imaging-guided atrial septal puncture by using a MR imaging-conspicuous blunt laser catheter that perforates only when energized.
  
  
  METHODS
  The authors customized a 0.9-mm clinical excimer laser catheter with a receiver coil to impart MR imaging visibility at 1.5 T. Seven swine underwent laser transseptal puncture under real-time MR imaging. MR imaging signal-to-noise ratio profiles of the device were obtained in vitro. Tissue traversal force was tested with a calibrated meter. Position was corroborated with pressure measurements, oximetry, angiography, and necropsy. Intentional non-target perforation simulated serious complication.
  
  
  RESULTS
  Embedded MR imaging antennae accurately reflected the position of the laser catheter tip and profile in vitro and in vivo. Despite having an increased profile from the microcoil, the 0.9-mm laser catheter traversed in vitro targets with similar force (0.22 N +/- 0.03) compared with the unmodified laser. Laser puncture of the atrial septum was successful and accurate in all animals. The laser was activated an average of 3.8 seconds +/- 0.4 before traversal. There were no sequelae after 6 hours of observation. Necropsy revealed 0.9-mm holes in the fossa ovalis in all animals. Intentional perforation of the aorta and atrial free wall was evident immediately.
  
  
  CONCLUSIONS
  MR imaging-guided laser puncture of the interatrial septum is feasible in swine and offers controlled delivery of perforation energy by using an otherwise blunt catheter. Instantaneous soft tissue imaging provides immediate feedback on safety.
authors: Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1538, USA.
authors: Abdalla A
authors: AA
authors: Elagha
authors: Ozgur
authors: O
authors: Kocaturk
authors: Michael A
authors: MA
authors: Guttman
authors: Cengizhan
authors: C
authors: Ozturk
authors: Ann H
authors: AH
authors: Kim
authors: George W
authors: GW
authors: Burton
authors: June H
authors: JH
authors: Kim
authors: Venkatesh K
authors: VK
authors: Raman
authors: Amish N
authors: AN
authors: Raval
authors: Victor J
authors: VJ
authors: Wright
authors: William H
authors: WH
authors: Schenke
authors: Elliot R
authors: ER
authors: McVeigh
authors: Robert J
authors: RJ
authors: Lederman
mesh_terms: D000818:Animals; D054087:Atrial Septum / Q000601:surgery*; D053685:Laser Therapy / Q000379:methods*; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013552:Swine