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      Transcatheter Pulmonary Valve Replacement by Hybrid Approach Using a Novel Polymeric Prosthetic Heart Valve: Proof of Concept in Sheep

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          Abstract

          Background

          Since 2000, transcatheter pulmonary valve replacement has steadily advanced. However, the available prosthetic valves are restricted to bioprosthesis which have defects like poor durability. Polymeric heart valve is thought as a promising alternative to bioprosthesis. In this study, we introduced a novel polymeric transcatheter pulmonary valve and evaluated its feasibility and safety in sheep by a hybrid approach.

          Methods

          We designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflets were made of 0.1-mm expanded polytetrafluoroethylene (ePTFE) coated with phosphorylcholine. We chose glutaraldehyde-treated bovine pericardium valves as control. Pulmonary valve stents were implanted in situ by a hybrid transapical approach in 10 healthy sheep (8 for polymeric valve and 2 for bovine pericardium valve), weighing an average of 22.5±2.0 kg. Angiography and cardiac catheter examination were performed after implantation to assess immediate valvular functionality. After 4-week follow-up, angiography, echocardiography, computed tomography, and cardiac catheter examination were used to assess early valvular function. One randomly selected sheep with polymeric valve was euthanized and the explanted valved stent was analyzed macroscopically and microscopically.

          Findings

          Implantation was successful in 9 sheep. Angiography at implantation showed all 9 prosthetic valves demonstrated orthotopic position and normal functionality. All 9 sheep survived at 4-week follow-up. Four-week follow-up revealed no evidence of valve stent dislocation or deformation and normal valvular and cardiac functionality. The cardiac catheter examination showed the peak-peak transvalvular pressure gradient of the polymeric valves was 11.9±5.0 mmHg, while that of two bovine pericardium valves were 11 and 17 mmHg. Gross morphology demonstrated good opening and closure characteristics. No thrombus or calcification was seen macroscopically.

          Conclusions

          This design of the novel ePTFE transcatheter pulmonary valve is safe and effective to deploy in sheep by hybrid approach, and the early valvular functionality is good.

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          Most cited references23

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          Percutaneous pulmonary valve implantation: impact of evolving technology and learning curve on clinical outcome.

          Percutaneous pulmonary valve implantation was introduced in the year 2000 as a nonsurgical treatment for patients with right ventricular outflow tract dysfunction. Between September 2000 and February 2007, 155 patients with stenosis and/or regurgitation underwent percutaneous pulmonary valve implantation. This led to significant reduction in right ventricular systolic pressure (from 63+/-18 to 45+/-13 mm Hg, P 25 mm Hg (log-rank test P=0.01) were associated with a higher risk of reoperations. Percutaneous pulmonary valve implantation resulted in the ability to avoid surgical right ventricular outflow tract revision in the majority of cases. This procedure might reduce the number of operations needed over the total lifetime of patients with right ventricle-to-pulmonary artery conduits.
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            Polymeric heart valves: new materials, emerging hopes.

            Heart valve (HV) replacements are among the most widely used cardiovascular devices and are in rising demand. Currently, clinically available devices are restricted to slightly modified mechanical and bioprosthetic valves. Polymeric HVs could represent an attractive alternative to the existing prostheses, merging the superior durability of mechanical valves and the enhanced haemodynamic function of bioprosthetic valves. After early unsatisfactory clinical results, polymeric HVs did not reach commercialization, mainly owing to their limited durability. Recent advances in polymers, nanomaterials and surface modification techniques together with the emergence of novel biomaterials have resulted in improved biocompatibility and biostability. Advances in HV design and fabrication methods could also lead to polymeric HVs that are suitable for long-lasting implantation. Considering all these progresses, it is likely that the new generation of polymeric HVs will find successful long-term clinical applications in future.
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              Crimping may affect the durability of transcatheter valves: an experimental analysis.

              Transcatheter aortic valve implantation has gained widespread acceptance to treat elderly high-risk patients with aortic stenosis. We used a subcutaneous rat model to evaluate whether crimping may affect valve long-term durability. Standard Sapien transcatheter valves (Edwards Lifesciences, Irvine, CA) were crimped for different durations (1 hour, 1 day, 1 month) and uncrimped, and leaflet pieces as well as control tissue (Perimount Magna, Edwards) were then implanted subcutaneously in 15 male weanling Sprague-Dawley rats for 12 weeks. Grade of calcification was measured by freeze-dried mass and van Kossa staining. Histologic and electron microscopic examination were performed to investigate potential leaflet-fragmentation caused by crimping. There were no differences in calcification among the groups. The calcium carbonate concentrations in all samples ranged from 0.1 to 100 mg/g dry weight. Leaflet morphology, however, differed from no fragmentation (control group) to highly fragmented tissue (1-month crimped). These differences reached statistical significance between crimped and non-crimped leaflets (p<0.003). Transcatheter valve crimping does not necessarily affect leaflet calcification. However, the structural changes of the leaflets that were caused by crimping may have clinical significance. Duration of crimping should be as short as possible, and very tight crimping to small diameters should be avoided. Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
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                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS One
                PLoS ONE
                plos
                plosone
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                1932-6203
                2014
                13 June 2014
                : 9
                : 6
                : e100065
                Affiliations
                [1 ]Department of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University, Shanghai, China
                [2 ]Centre of Cardiovascular Surgery, Guangzhou General Hospital of Guangzhou Military Region, Guangzhou, China
                [3 ]Department of Cardiology, Changhai Hospital, Second Military Medical University, Shanghai, China
                Sapienza University of Rome, Italy
                Author notes

                Competing Interests: The authors have declared that no competing interests exist.

                Conceived and designed the experiments: LH ZX. Performed the experiments: BZ XC TX ZZ XL LH. Analyzed the data: BZ XC. Contributed reagents/materials/analysis tools: ZX. Wrote the paper: BZ XC.

                Article
                PONE-D-14-03243
                10.1371/journal.pone.0100065
                4057289
                24926892
                7f46cb1c-0959-4024-a6f3-517499a92deb
                Copyright @ 2014

                This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

                History
                : 23 January 2014
                : 21 May 2014
                Page count
                Pages: 9
                Funding
                The authors have no support or funding to report.
                Categories
                Research Article
                Biology and Life Sciences
                Biotechnology
                Biomaterials
                Medicine and Health Sciences
                Cardiology
                Cardiovascular Diseases
                Valvular Diseases
                Interventional Cardiology
                Surgical and Invasive Medical Procedures
                Cardiothoracic Surgery

                Uncategorized
                Uncategorized

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