• Keith A Horvath, Dumitru Mazilu, Junfeng Cai, Bogdan Kindzelski, and Ming Li.
• Cardiothoracic Surgery Research Program, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md. Electronic address: horvathka@mail.nih.gov.
• J. Thorac. Cardiovasc. Surg. 2015 Apr 1; 149 (4): 1067-72.

ObjectivesDespite 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.MethodsA 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.ResultsThe 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.ConclusionsWe 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.Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

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