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Characterization of Turbulent Flow Behind a Transcatheter Aortic Valve in Different Implantation Positions.

ABSTRACT: The development of turbulence after transcatheter aortic valve (TAV) implantation may have detrimental effects on the long-term performance and durability of the valves. The characterization of turbulent flow generated after TAV implantation can provide fundamental insights to enhance implantation techniques. A self-expandable TAV was tested in a pulse replicator and the three-dimensional flow field was extracted by means of tomographic particle image velocimetry. The valve was fixed inside a silicone phantom mimicking the aortic root and the flow field was studied for two different supra-annular axial positions at peak systole. Fluctuating velocities and turbulent kinetic energy were compared between the two implantations. Velocity spectra were derived at different spatial positions in the turbulent wakes to characterize the turbulent flow. The valve presented similar overall flow topology but approximately 8% higher turbulent intensity in the lower implantation. In this configuration, axial views of the valve revealed smaller opening area and more corrugated leaflets during systole, as well as more accentuated pinwheeling during diastole. The difference arose from a lower degree of expansion of the TAV's stent inside the aortic lumen. These results suggest that the degree of expansion of the TAV in-situ is related to the onset of turbulence and that a smaller and less regular opening area might introduce flow instabilities that could be detrimental for the long-term performance of the valve. The present study highlights how implantation mismatches may affect the structure and intensity of the turbulent flow in the aortic root.

SUBMITTER: Pietrasanta L

PROVIDER: S-EPMC8794584 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Aortic sinus flow stasis likely in valve-in-valve transcatheter aortic valve implantation.

Project description:OBJECTIVE:Valve-in-valve procedures using transcatheter aortic valves are increasingly performed to treat degenerated bioprosthetic surgical aortic valves because they are less invasive than redo aortic valve replacement. The objective of this study is to quantify the changes in aortic sinus blood flow dynamics before and after a valve-in-valve procedure to gain insight into mechanisms for clinical and subclinical thrombosis of leaflets. METHODS:A detailed description of the sinus hemodynamics for valve-in-valve implantation was performed in vitro. A Medtronic Hancock II (Medtronic Inc, Minneapolis, Minn) porcine bioprosthesis was modeled as a surgical aortic valve, and Medtronic CoreValve and Edwards Sapien (Edwards Lifesciences, Irvine, Calif) valves were used as the transcatheter aortic valves. High-resolution particle image velocimetry was used to compare the flow patterns from these 2 valves within both the left coronary and noncoronary sinuses in vitro. RESULTS:Velocity and vorticity within the surgical valve sinuses reached peak values of 0.7 m/s and 1000 s-1, with a 70% decrease in peak fluid shear stress near the aortic side of the leaflet in the noncoronary sinus. With the introduction of transcatheter aortic valves, peak velocity and vorticity were reduced to approximately 0.4 m/s and 550 s-1 and 0.58 m/s and 653 s-1 without coronary flow and 0.60 m/s and 631 s-1 and 0.81 m/s and 669 s-1 with coronary flow for the CoreValve and Sapien valve-in-valve implantations, respectively. Peak shear stress was approximately 38% higher along the aortic side of the coronary versus noncoronary transcatheter aortic valve leaflet. CONCLUSIONS:Decreased flow and shear stress in valve-in-valve procedures indicate a higher risk of leaflet thrombosis secondary to flow stasis, perhaps more so in the noncoronary sinus.

| S-EPMC5479725 | biostudies-literature

Cerebral Blood Flow in Patients with Severe Aortic Valve Stenosis Undergoing Transcatheter Aortic Valve Implantation.

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| S-EPMC7894507 | biostudies-literature

Outcomes of Redo Transcatheter Aortic Valve Implantation for Structural Valve Degeneration of Transcatheter Aortic Valve.

Project description:Background: The outcome of redo transcatheter aortic valve (TAV) implantation (TAVI) is unknown for TAV structural valve degeneration (SVD). This paper reports the initial results of redo TAVI for TAV-SVD in Japanese patients. Methods?and?Results: Of 630 consecutive patients, 6 (1.0%) underwent redo TAVI for TAV-SVD (689-1,932 days after the first TAVI). The first TAV were 23-mm balloon-expandable valves (BEV, n=5) and a 26-mm self-expandable valve (SEV, n=1). All patients underwent multidetector computed tomography (MDCT) before redo TAVI, which showed first-TAV under-expansion (range, 19.1-21.0 mm) compared with the label size. Two BEV and 4 SEV were successfully implanted as second TAV, without moderate/severe regurgitation or 30-day mortality. One of 2 patients with a BEV-inside-BEV implantation had a high transvalvular mean pressure gradient post-procedurally (34 mmHg) and required surgical valve replacement 248 days after the redo TAVI. This, however, was unnoted in patients with SEV implantation during redo TAVI. Planned coronary artery bypass grafting was concomitantly performed in 1 patient with a small sino-tubular junction and SEV-inside-SEV implantation because of the risk of coronary malperfusion caused by the first TAV leaflets. Five of the 6 patients survived during the follow-up period (range, 285-1,503 days). Conclusions: Redo TAVI for TAV-SVD appears safe and feasible, while specific strategies based on MDCT and device selection seem important for better outcomes.

| S-EPMC7890286 | biostudies-literature

Transcatheter aortic valve implantation in Asia.

Project description:The use of transcatheter aortic valve implantation (TAVI) to treat severe symptomatic aortic valve stenosis has increased exponentially in the last decade. This rapid expansion was seen predominantly in Western developed nations and has been fuelled by favorable results reported from a plethora of well-publicized randomized controlled trials, large retrospective series and national registries. Now, TAVI has become the standard of care for inoperable patients and an alternative to open surgery in patients who are at intermediate to high risk for open surgery. Notwithstanding these positive results, Asia has been relatively slow to adopt this technology despite a potentially large patient pool. Unique features of Asian medical environments and differences in Asian anatomy affecting TAVI uptake in Asia will be discussed. This article serves to outline the various challenging aspects of disseminating TAVI in Asian countries.

| S-EPMC5639230 | biostudies-literature

Transcatheter aortic valve implantation: status update.

Project description:Transcatheter aortic valve implantation (TAVI) has emerged as the gold standard technique for all patients with symptomatic severe aortic stenosis at elevated surgical risk. Much progress has been made to reduce procedural complications and improve patient outcomes. The impressive results of contemporary TAVI can be attributed to a variety of factors, including improving operator experience, pre-operative patient screening, and developments in transcatheter heart valve and delivery system technology. Despite these advances, serious procedural complications continue to occur and there remain some anatomical subsets and patient groups to whom TAVI technology has not been expanded. Herein we discuss these unmet needs in TAVI.

| S-EPMC6242924 | biostudies-literature

Repeated transcatheter aortic valve implantation for the treatment of a degenerated transcatheter aortic valve implantation valve (valve-in-valve technique): a case report.

Project description:BackgroundValve-in-valve transcatheter aortic valve implantation (TAVI) has emerged as a competent alternative for the treatment of degenerated bioprosthetic valves after surgical aortic valve replacement, or during TAVI procedure as a bailout option. Herein, we report a rare case of a self-expandable Medtronic Evolut R valve into a failing Medtronic CoreValve, with the use of modern pre-TAVI imaging screening, suggesting the proper procedural design steps for so complicated implantations.Case summaryA frail 78-year-old woman with a degenerated Medtronic Core Valve 26 mm bioprosthesis, implanted in 2011 due to severe aortic stenosis, was referred to our hospital due to worsening dyspnoea New York Heart Association III. The screening echocardiography documented severe aortic stenosis, while the classical risk scores were in favour of repeated TAVI (EuroSCORE II 5.67%). Computed tomography measurements and three-dimensional (3D) printing model were of great help for the proper valve selection (Medtronic Evolut R 26 mm), while the use of cerebral protection device (Claret Sentinel) was considered as a necessary part of the procedure. The simultaneous use of fluoroscopy and transoesophageal echocardiogram led to optimal haemodynamic result, confirmed by the discharge echocardiogram, with a significant clinical improvement during the first month follow-up.DiscussionThe main periprocedural concerns remain valve malpositioning, coronary artery obstruction, and high remaining transvalvular gradients. The multimodality pre-TAVI imaging screening may be helpful for precise procedural design. Despite the limited use of 3D models, it is necessary to adopt such tissue-mimicking phantoms to increase the possibility of optimal procedural result.

| S-EPMC8183662 | biostudies-literature

Antithrombotic Therapy After Transcatheter Aortic Valve Implantation.

Project description:The development of transcatheter aortic valve implantation has represented one of the greatest advances in the cardiology field in recent years and has changed clinical practice for patients with aortic stenosis. Despite the continuous improvement in operators' experience and techniques, and the development of new generation devices, thromboembolic and bleeding complications after transcatheter aortic valve implantation remain frequent, and are a major concern due to their negative impact on prognosis in this vulnerable population. In addition, the optimal antithrombotic regimen in this scenario is not known, and current recommendations are mostly empirical and not evidence based. The present review aims to provide an overview of the current status of knowledge, including relevant on-going randomised trials, on antithrombotic treatment strategies after transcatheter aortic valve implantation.

| S-EPMC7066806 | biostudies-literature

"Cusp-overlap" technique simplifies the implantation of Chinese domestic transcatheter valve in transcatheter aortic valve implantation.

Project description: Not available

| S-EPMC8078441 | biostudies-literature

Transcatheter aortic valve implantation economics: a grisly reality.

Project description:Transcatheter aortic valve implantation (TAVI), an established treatment for inoperable and high-risk operable symptomatic patients with severe aortic stenosis with growing numbers of procedures and expanding indications, is an expensive therapy. Cost-effectiveness analyses rely on the value of the incremental cost-effectiveness ratio (ICER), which is the difference in cost between two possible interventions, divided by the difference in their effect. Several analyses have demonstrated that TAVI is cost-effective with an acceptable ICER for the inoperable patient alone and only via the iliofemoral route, while TAVI is more costly and is either less or equally effective as surgery in high-risk operable patients. When use of TAVI is extended to include a larger number of patients suitable for surgery, the overall results become less favorable. Acceptable ICERs should practically equate to the value of the gross domestic product (GDP) per capita in each country; however, the cost of the TAVI kit alone already exceeds the GDP per capita of all moderate- and low-income countries. An overview of the current cost-efficacy issues of TAVI is presented and this grisly reality is discussed, which may hopefully be improved in the future.

| S-EPMC5639228 | biostudies-other

Does transcatheter aortic valve implantation mean the end of surgical aortic valve replacement?

Project description:Although the results of the early TAVI experience are promising, longer-term follow-up is necessary before the procedure can be extended to lowerrisk patients. Many issues are not yet resolved, including the long-term effects of paravalvular leaks (which occur in most TAVI patients), the true stroke rate in TAVI patients (which is probably in the range of 5% to 6%), and the need for permanent pacemaker implantation (which ranges from 5% to 40% in TAVI patients, depending upon the device used). As the procedure is extended into the lower-risk population, these issues will assume greater import than they have in the population currently in treatment—very elderly, high-risk patients with limited life expectancy. As in the coronary-revascularization paradigm of percutaneous coronary intervention versus coronary artery bypass grafting, there will be increasing adoption of the transcatheter approach. Just as the rumors of the demise of surgical bypass were premature, conventional AVR will continue to be the predominant technique for the treatment of aortic stenosis during at least the next decade. Although the percentage of patients treated by a transcatheter approach will continue to increase, regulatory and reimbursement factors are likely to be the primary determinants of the rate of adoption.

| S-EPMC3014148 | biostudies-other

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