31 research outputs found

    Biomechanics of transapical mitral valve implantation

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    2014 Summer.Includes bibliographical references.Heart disease is the number one killer in the United States. Within this sector, valve disease plays a very important role: Approximately 6% of the entire population has either prolapse or stenosis of the mitral valve and this percentage only increases when looking only at the elderly population. Transapical mitral valve implantation has promised to be a potential therapy for high-risk patients presenting with MR; however it is unclear what the best method of securing a valve within the mitral annulus may be to provide a safe and efficient valve replacement. The objective of this research is to study and understand the underlying biomechanics of fixation of transapical mitral valves within the native mitral annulus. Two different transapical mitral valve prosthesis designs were tested: One valve design has a portion of the leaflets atrialized such that it has a shorter stent height and the valve itself sits within the native annulus, the other design is not atrialized and protrudes further into the left ventricle. The valves were implanted in a left heart simulator to assess leaflet kinematics and hemodynamics using high speed imagery and particle image velocimetry techniques. An in vitro passive beating heart model was then used to assess the two different fixation methods (namely, anchored at the apex vs. anchored at the annulus) with respect to paravalvular regurgitation. Leaflet kinematics and hemodynamics revealed proper leaflet coaptation and acceptable pressure gradients and inflow fillings; however, both designs yielded elevated turbulence stresses within the ventricle. At 60 beats per minute, leaflet opening and closing times were both under 0.1 seconds, max Reynolds shear stresses were between 40 and 60 N/m2 and maximum velocities were approximately 1.4 m/s. Assessment of the different fixation methods during implantation revealed the superiority of the atrialized valve when anchored at the annulus (p<0.05), but showed no such comparison during tethered implantation. In addition to the results of statistical testing, observations show that the importance of the relationship between ventricular stent height and fixation method compared with native anatomy plays an important role in overall prosthesis function regardless of implantation method

    An innovative design of transcatheter implantable mitral valve prosthesis. Anatomy of the mitral valve in patients with functional mitral regurgitation and preliminary results of the implant in the animal model using quantitative 3D echocardiography and particle imaging velocimetry

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    Background: Transcatheter mitral valve replacement (TMVR) is a new therapeutic option for high surgical risk patients with mitral regurgitation (MR) and several prostheses are currently at different stages of development. Indeed, once prototypes of these prosthesis are designed, they need to undergo both bench testing and preclinical evaluation to test the performance and safety of the device and acquire useful information for guiding the secondary improvements. After this stage, if the prosthesis shows favourable results in terms of performance and safety, the manufacturer can apply for CE marking. In case of achievement of the CE mark, the clinical use can start in the European countries. The application of advanced echocardiography is useful not only in a preclinical experimental stage but results to be an irreplaceable tool in the proper selection of the treatment strategy with respect to the case-specific anatomic and functional mitral valve (MV) disease pattern and in the guidance of the correct bioprosthesis positioning and implantation during the procedure. Aims: To describe the feasibility and advantage of 3D and contrast echocardiography in a preclinical study and report the acute hemodynamic results after implantation of a novel transcatheter self- expandable D-shape mitral bioprosthesis characterized by asymmetric stent and advanced mono- leaflet structure. In addition, we aimed to assess the MV geometry in patients with functional MR (FMR) that would potentially benefit from TMVR, focusing on the comparison between mitral annulus (MA) geometry of patients with ischemic (IMR) and non-ischemic mitral regurgitation (nIMR). Methods: From May 2015 to August 2018, prosthesis prototypes were implanted under echocardiography guidance in 112 small-size healthy sheep using both trans-atrial (Ta) and trans- apical (TA) access. Multimodality imaging was used for animal selection and trans-pericardial echocardiography (TPE) was applied to obtain humanized image during intervention. Particle imaging velocimetry was used to assess intraventricular flow dynamics. We retrospectively selected 94 patients with severe FMR, both IMR and nIMR. 3D MA analysis was performed in early-diastole and mid-systoleby using a recent, commercially-available software package. Measure of interest were MA dimensions and geometry parameters, left atrial and left ventricular volumes. Results: 2D and 3D TPE was performed before and after implantation to measure MA dimensions (area: 6.4±0.8 cm2, perimeter: 9.4±0.8 cm) and assess prosthesis alignment and function. The vast majority of implantations showed none or just trivial intra- (n=104, 93%) and peri-prosthesis leak (n=86, 77%) with good valve function (mean gradient 4 ± 3 mmHg). At particle imaging velocimetry, left ventricular vortex properties did not change after implantation. In patients with severe FMR, 41 (43,6%) with IMR and 53 (56,4%) with nIMR, maximum MA 3D area (10.7±2.5 cm2 vs 11.6±2.7 cm2, p=0.124) and the best fit plane MA area (9.9±2.3 cm2 vs 10.7±2.5 cm2, p=0.135, respectively) were similar between IMR and nIMR. nIMR patients showed larger mid- systolic 3D area (9.8±2.3 cm2 vs 10.8±2.7 cm2, p=0.046) and perimeter (11.2±1.3 cm vs 11.8±1.5 cm, p=0.048), longer and larger leaflets, and wider aorto-mitral angle (135±10° vs 141±11°, p=0.011). Conversely, the area of MA at the best fit plane did not differ between IMR and nIMR patients (9±1.1 cm2 vs 9.9±1.5 cm2, p=0.063). Conclusions: In the healthy sheep model, initial preclinical experience with a novel mono-leaflet transcatheter self-expandable mitral prosthesis showed that the TA implantation of the valve was feasible, safe, and supported by good hemodynamic results. The application of advanced echocardiography on an animal model was feasible and helpful in guiding the continuous refinements needed to enhance the development of this new concept of bioprosthesis. Patients with ischemic and non-ischemic etiology of FMR have similar maximum dimension, yet systolic differences between the two groups should be considered to tailor prosthesis’s selection

    Transcatheter Therapies for the Treatment of Valvular and Paravalvular Regurgitation in Acquired and Congenital Valvular Heart Disease

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    AbstractTranscatheter therapies in structural heart disease have evolved tremendously over the past 15 years. Since the introduction of the first balloon-expandable valves for stenotic lesions with implantation in the pulmonic position in 2000, treatment for valvular heart disease in the outflow position has become more refined, with newer-generation devices, alternative techniques, and novel access approaches. Recent efforts into the inflow position and regurgitant lesions, with transcatheter repair and replacement technologies, have expanded our potential to treat a broader, more heterogeneous patient population. The evolution of multimodality imaging has paralleled these developments. Three- and 4-dimensional visualization and concomitant use of novel technologies, such as fusion imaging, have supported technical growth, from pre-procedural planning and intraprocedural guidance, to assessment of acute results and follow-up. A multimodality approach has allowed operators to overcome many limitations of each modality and facilitated integration of a multidisciplinary team for treatment of this complex patient population

    Transcatheter Mitral Valve Replacement: Structural and Hemodynamic Analysis

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    Transcatheter mitral valve replacement (TMVR) is being developed to become a substitute therapy for surgery in prohibitive or high surgical risk patients to treat severe mitral regurgitation. A limited number of TMVR systems are under clinical evaluation. However, transcatheter mitral valve (TMV) long-term durability and hemodynamic performance is not known. TMV durability and hemodynamics must match with that of surgical bioprostheses for potential commercialization of TMVR. Experimental and computational approaches were used to find the leaflets’ three-dimensional anisotropic mechanical properties in a transcatheter Edwards SAPIEN 3 valve and a surgical Carpentier-Edwards PERIMOUNT Magna mitral valve and finite element (FE) simulations were conducted to obtain the stress distribution on both valves. Moreover, to visualize the flow field within the left heart, steady-state computational fluid dynamics (CFD) simulations were run. The FE simulations demonstrated that in a cardiac cycle, at peak systole, the highest stress value in the two bioprostheses was 4.75 and 16 MPa for the surgical and transcatheter heart valve, respectively. After studying the leaflet stress distributions and flow field, long-term durability may potentially be different between the two models. The results of CFD simulations could potentially show that TMVs with supra-annular positioning have a higher risk of leaflet thrombosis as opposed to the intra-annular position

    Transcatheter Mitral Valve Replacement: Evolution and Future Development

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    We will review transcatheter mitral valve replacement (TMVR) and discuss this evolving cutting edge procedure in terms of types (valve in valve, valve in ring and valve in mitral annular calcification MAC), clinical indications, pre-procedural planning and value of pre-procedural imaging including computed tomography role, technical challenges encountered in these procedures, potential complications for each type of TMVR, and potential strategies to mitigate and avoid such complications, We will review the currently available devices dedicated for mitral valve replacement, with a summary of their preliminary data and early outcome results. We will also discuss knowledge gaps and ideas for future research

    Design, Analysis and Testing of a Novel Mitral Valve for Transcatheter Implantation

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    Mitral regurgitation is a common mitral valve dysfunction which may lead to heart failure. Because of the rapid aging of the population, conventional surgical repair and replacement of the pathological valve are often unsuitable for about half of symptomatic patients, who are judged high-risk. Transcatheter valve implantation could represent an effective solution. However, currently available aortic valve devices are inapt for the mitral position. This paper presents the design, development and hydrodynamic assessment of a novel bi-leaflet mitral valve suitable for transcatheter implantation. The device consists of two leaflets and a sealing component made from bovine pericardium, supported by a self-expanding wireframe made from superelastic NiTi alloy. A parametric design procedure based on numerical simulations was implemented to identify design parameters providing acceptable stress levels and maximum coaptation area for the leaflets. The wireframe was designed to host the leaflets and was optimised numerically to minimise the stresses for crimping in an 8 mm sheath for percutaneous delivery. Prototypes were built and their hydrodynamic performances were tested on a cardiac pulse duplicator, in compliance with the ISO5840-3:2013 standard. The numerical results and hydrodynamic tests show the feasibility of the device to be adopted as a transcatheter valve implant for treating mitral regurgitation

    Advances in transcatheter mitral and tricuspid therapies

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    BACKGROUND: While rheumatic mitral stenosis has been effectively treated percutaneously for more than 20 years, mitral and tricuspid regurgitation treatment appear as a contemporary unmet need. The advent of transcatheter therapies offer new treatment options to often elderly and frail patients at high risk for open surgery. We aimed at providing an updated review of fast-growing domain of transcatheter mitral and tricuspid technology. MAIN BODY: We reviewed the existing literature on mitral and tricuspid transcatheter therapies. Mitraclip is becoming an established therapy for secondary mitral regurgitation in selected patients with disproportionately severe regurgitation associated with moderate left ventricle dysfunction. Evidence is less convincing for primary mitral regurgitation. Transcatheter mitral valve replacement is a promising emerging alternative to transcatheter repair, for secondary as well as primary mitral regurgitation. But further development is needed to improve delivery. Transcatheter tricuspid intervention arrives late after similar technologies have been developed for aortic and mitral valves and is currently at its infancy. This is likely due in part to previously under-recognized impact of tricuspid regurgitation on patient outcomes. Edge-to-edge repair is the most advanced transcatheter solution in development. Data on tricuspid annuloplasty and replacement is limited, and more research is warranted. CONCLUSION: The future appears bright for transcatheter mitral therapies, albeit their place in clinical practice is yet to be clearly defined. Tricuspid transcatheter therapies might address the unmet need of tricuspid regurgitation treatment

    Current Devices and Complications Related to Transcatheter Mitral Valve Replacement: The Bumpy Road to the Top

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    Mitral regurgitation is the most common valvular lesion in the developed world, with increasing prevalence, morbidity, and mortality. The experience with surgical mitral valve repair or replacement is very well-validated. However, more than 45% of these patients get denied surgery due to an elevated risk profile and advanced disease of the left ventricle at the time of presentation, promoting the need for less invasive transcatheter options such as transcatheter repair and transcatheter mitral valve replacement (TMVR). Early available TMVR studies have shown promising results, and several dedicated devices are under clinical evaluation. However, TMVR is still in the early developmental stages and is associated with a non-negligible risk of periprocedural and post-procedural complications. In this review, we discuss the current challenges facing TMVR and the potential TMVR-related complications, offering an overview on the measures implemented to mitigate these complications, and future implications

    Design, Analysis and Testing of a Novel Mitral Valve for Transcatheter Implantation

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    Mitral regurgitation is a common mitral valve dysfunction which may lead to heart failure. Because of the rapid aging of the population, conventional surgical repair and replacement of the pathological valve are often unsuitable for about half of symptomatic patients, who are judged high-risk. Transcatheter valve implantation could represent an effective solution. However, currently available aortic valve devices are inapt for the mitral position. This paper presents the design, development and hydrodynamic assessment of a novel bi-leaflet mitral valve suitable for transcatheter implantation. The device consists of two leaflets and a sealing component made from bovine pericardium, supported by a self-expanding wireframe made from superelastic NiTi alloy. A parametric design procedure based on numerical simulations was implemented to identify design parameters providing acceptable stress levels and maximum coaptation area for the leaflets. The wireframe was designed to host the leaflets and was optimised numerically to minimise the stresses for crimping in an 8&nbsp;mm sheath for percutaneous delivery. Prototypes were built and their hydrodynamic performances were tested on a cardiac pulse duplicator, in compliance with the ISO5840-3:2013 standard. The numerical results and hydrodynamic tests show the feasibility of the device to be adopted as a transcatheter valve implant for treating mitral regurgitation

    Transcatheter Mitral Valve Replacement: Current Evidence and Concepts

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    Over the past decade, several transcatheter devices have been developed to address the treatment of severe mitral regurgitation (MR) in patients at high surgical risk, mainly aimed at repairing the native mitral valve (MV). MV repair devices have recently been shown to have high efficacy and safety. However, to replicate promising trial results, specific anatomical and pathophysiological criteria have to be met and operators need a high level of experience. As yet, the longer-term durability of transcatheter MV repair remains unknown. Transcatheter MV replacement (TMVR) might be a treatment option able to target various anatomies, reliably abolish MR, and foster ease of use with a standardised implantation protocol. This review presents upcoming TMVR devices and available data and discusses how TMVR might further advance the field of transcatheter treatment of MR
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