title: Transapical sutureless aortic valve implantation under magnetic resonance imaging guidance: Acute and short-term results.
abstract: OBJECTIVE
  Despite the increasing success and applicability of transcatheter aortic valve replacement, 2 critical issues remain: the durability of the valves, and the ideal imaging to aid implantation. This study was designed to investigate the transapical implantation of a device of known durability using real-time magnetic resonance imaging (MRI) guidance.
  
  
  METHODS
  A sutureless aortic valve was used that employs a self-expanding nitinol stent and is amenable to transapical delivery. MRI (1.5-T) was used to identify the anatomic landmarks in 60-kg Yucatan swine. Prostheses were loaded into an MRI-compatible delivery device with an active guidewire to enhance visualization. A series of acute feasibility experiments were conducted (n = 10). Additional animals (n = 6) were allowed to survive and had follow-up MRI scans and echocardiography at 90 days postoperatively. Postmortem gross examination was performed.
  
  
  RESULTS
  The valve was MRI compatible and created no significant MRI artifacts. The 3 commissural struts were visible on short-axis view; therefore, coronary ostia obstruction was easily avoided. The average implantation time was 65 seconds. Final results demonstrated stability of the implants with preservation of myocardial perfusion and function over 90 days: the ejection fraction was 48% ± 15%; the peak gradient was 17.3 ± 11.3 mm Hg; the mean gradient was 9.8 ± 7.2 mm Hg. Mild aortic regurgitation was seen in 4 cases, trace in 1 case, and a severe central jet in 1 case. Prosthesis positioning was evaluated during gross examination.
  
  
  CONCLUSIONS
  We demonstrated that a sutureless aortic valve can be safely and expeditiously implanted through a transapical approach under real-time MRI guidance. Postimplantation results showed a well-functioning prosthesis, with minimal regurgitation, and stability over time.
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
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: Junfeng
authors.initials: J
authors.lastname: Cai
authors.affiliation: Cardiothoracic Surgery Research Program, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Kindzelski
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
mesh_terms: D059925:Anatomic Landmarks; D000818:Animals; D001021:Aortic Valve / Q000503:physiopathology / Q000601:surgery*; D001022:Aortic Valve Insufficiency / Q000209:etiology / Q000503:physiopathology; D016477:Artifacts; D003326:Coronary Circulation; D005240:Feasibility Studies; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D023421:Models, Animal; D061646:Operative Time; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D013318:Stroke Volume; D034421:Sus scrofa; D013997:Time Factors