title: Real-time magnetic resonance imaging-guided transcatheter aortic valve replacement.
abstract: OBJECTIVE
  To demonstrate the feasibility of Real-time magnetic resonance imaging (rtMRI) guided transcatheter aortic valve replacement (TAVR) with an active guidewire and an MRI compatible valve delivery catheter system in a swine model.
  
  
  METHODS
  The CoreValve system was minimally modified to be MRI-compatible by replacing the stainless steel components with fluoroplastic resin and high-density polyethylene components. Eight swine weighing 60-90 kg underwent rtMRI-guided TAVR with an active guidewire through a left subclavian approach.
  
  
  RESULTS
  Two imaging planes (long-axis view and short-axis view) were used simultaneously for real-time imaging during implantation. Successful deployment was performed without rapid ventricular pacing or cardiopulmonary bypass. Postdeployment images were acquired to evaluate the final valve position in addition to valvular and cardiac function.
  
  
  CONCLUSIONS
  Our results show that the CoreValve can be easily and effectively deployed through a left subclavian approach using rtMRI guidance, a minimally modified valve delivery catheter system, and an active guidewire. This method allows superior visualization before deployment, thereby allowing placement of the valve with pinpoint accuracy. rtMRI has the added benefit of the ability to perform immediate postprocedural functional assessment, while eliminating the morbidity associated with radiation exposure, rapid ventricular pacing, contrast media renal toxicity, and a more invasive procedure. Use of a commercially available device brings this rtMRI-guided approach closer to clinical reality.
authors.affiliation: Cardiothoracic Surgery Research Program, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Md.
authors.forename: Justin G
authors.initials: JG
authors.lastname: Miller
authors.affiliation: Cardiothoracic Surgery Research Program, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Md.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.affiliation: Cardiothoracic Surgery Research Program, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Md.
authors.forename: Dumitru
authors.initials: D
authors.lastname: Mazilu
authors.affiliation: Cardiothoracic Surgery Research Program, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Md.
authors.forename: Tim
authors.initials: T
authors.lastname: Hunt
authors.affiliation: Cardiothoracic Surgery Research Program, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Md. Electronic address: horvathka@mail.nih.gov.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Horvath
mesh_terms: D000818:Animals; D001024:Aortic Valve Stenosis / Q000175:diagnosis* / Q000601:surgery*; D001705:Bioprosthesis; D004195:Disease Models, Animal; D005260:Female; D006350:Heart Valve Prosthesis; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects / Q000379:methods; D061646:Operative Time; D011183:Postoperative Complications / Q000453:epidemiology / Q000503:physiopathology; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011897:Random Allocation; D012680:Sensitivity and Specificity; D013552:Swine; D065467:Transcatheter Aortic Valve Replacement / Q000009:adverse effects / Q000379:methods*
keywords: Medtronic CoreValve; real-time magnetic resonance image; swine animal model; transcatheter aortic valve replacement