On the Mechanics of Transcatheter Aortic Valve Replacement

Dasi, Lakshmi Prasad; Hatoum, Hoda; Kheradvar, Arash; Zareian, Ramin; Alavi, S. Hamed; Sun, Wei; Martin, Caitlin; Pham, Thuy M.; Wang, Qian; Midha, Prem A.; Raghav, Vrishank; Yoganathan, Ajit P.

doi:10.1007/s10439-016-1759-3

Cited by 74 publications

(69 citation statements)

References 150 publications

(232 reference statements)

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“…Furthermore, our pulse duplicator studies show comparable deleterious AGE-related effects on BHVs in flow simulation performance between our TAVR valve prototype and clinical-grade valves. As structural damage associated with leaflet crimping during TAVR valve preparation 75,76 and increasingly thinner leaflet material [76][77][78] are intrinsic characteristics to TAVR versus SAVR valves, it is important to understand the implications of AGE accumulation and microstructural modification on long-term bioprosthesis durability.…”

Section: Discussionmentioning

confidence: 99%

Glycation and Serum Albumin Infiltration Contribute to the Structural Degeneration of Bioprosthetic Heart Valves

Frasca

Xue

Kossar

et al. 2020

Preprint

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Background: Bioprosthetic heart valves (BHV) are widely used to treat heart valve disease but are fundamentally limited by structural valve degeneration (SVD). Non-calcific mechanisms of SVD entirely account for approximately 30% of SVD cases and contribute to calcific SVD but remain understudied. Glycation mechanisms have not been previously associated with SVD, despite being established as degenerative in collagenous native tissues. Objectives:To determine whether blood component infiltration-based glycation and concomitant human serum albumin (HSA) deposition contribute mechanistically to SVD.Methods: Immunohistochemistry (IHC) was used to identify advanced glycation end-products (AGEs) and serum albumin accumulation in 45 aortic valve BHV explanted due to SVD, glutaraldehyde-treated bovine pericardium (BP) incubated in vitro in glyoxal and HSA, and rat subcutaneous BP implants. Structural impacts of glycation-related mechanisms were evaluated by second harmonic generation (SHG) collagen imaging. Hydrodynamic effects of valve glycation and concomitant HSA exposure were studied with an ISO-5840-compliant pulse duplicator system using surgical grade BHV.Results: All 45 clinical explants and in vitro-incubated BP demonstrated accumulated AGE and HSA compared to un-implanted, un-exposed BHV. SHG revealed instigation of collagen malalignment similar to that in SVD explants by glycation and HSA infiltration. Rat subdermal explants also showed AGE and serum albumin accumulation. Pulse duplication demonstrated significantly reduced orifice area and increased pressure gradient and peak fluid velocity following glyoxal and HSA incubations. Conclusions:Glycation and concomitant HSA infiltration occur in clinical BHV and contribute to structural and functional degeneration of leaflet tissue, thus representing novel, interacting mechanisms of BHV SVD.

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Section: Discussionmentioning

confidence: 99%

Glycation and Serum Albumin Infiltration Contribute to the Structural Degeneration of Bioprosthetic Heart Valves

Frasca

Xue

Kossar

et al. 2020

Preprint

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“…Persistent complications that are associated with the tissue-based TAVR devices in the current cohort of high-risk surgical patients may impede the current expansion to lower-risk patients. 12 Large randomized studies are currently underway for low-risk surgical patients, with small studies showing TAVR and SAVR equivalence. However, long term effects concerning long term durability and potential complications specific to younger patients (i.e.…”

Section: Introductionmentioning

confidence: 99%

Novel Polymeric Valve for Transcatheter Aortic Valve Replacement Applications: In Vitro Hemodynamic Study

et al. 2018

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Transcatheter aortic valve replacement (TAVR) is a minimally-invasive approach for treating severe aortic stenosis. All clinically-used TAVR valves to date utilize chemically-fixed xenograft as the leaflet material. Inherent limitation of the tissue (e.g., calcific degeneration) motivates the search for alternative leaflet material. Here we introduce a novel polymeric TAVR valve that was designed to address the limitations of tissue-valves. In this study, we experimentally evaluated the hemodynamic performance of the valve and compared its performance to clinically-used valves: a gold standard surgical tissue valve, and a TAVR valve. Our comparative testing protocols included: (i) baseline hydrodynamics (ISO:5840-3), (ii) complementary patient-specific hydrodynamics in a dedicated system, and (iii) thrombogenicity. The patient-specific testing system facilitated comparing TAVR valves performance under more realistic conditions. Baseline hydrodynamics results at CO 4-7 L/min showed superior effective orifice area (EOA) for the polymer valve, most-notably as compared to the reference TAVR valve. Regurgitation fraction was higher in the polymeric valve, but within the ISO minimum requirements. Thrombogenicity trends followed the EOA results with the polymeric valve being the least thrombogenic, and clinical TAVR being the most. Hemodynamic-wise, the results strongly indicate that our polymeric TAVR valve can outperform tissue valves.

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“…Thrombosis is most likely to occur in low-flow or stasis regions with reduced shear stresses 2, 22, 31 . In healthy blood vessels, shear stress values range from 1.5 to 2Pa 13, 22, 32 .Usually shear stress varies with the local conditions and the flow rate.…”

Section: Discussionmentioning

confidence: 99%

“…Adverse effects such as elevated post-procedure pressure gradients, paravalvular leakage, coronary obstruction and recently sub-clinical leaflet thrombosis have been associated with TAVR 2–5 . Leaflet thrombosis in particular can be identified with Computed Tomography (CT) imaging 5, 6 .…”

Section: Introductionmentioning

confidence: 99%

Sinus Hemodynamics Variation with Tilted Transcatheter Aortic Valve Deployments

et al. 2018

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Leaflet thrombosis is a complication associated with transcatheter aortic valve (TAV) replacement (TAVR) correlated with sinus flow stasis. Sinus hemodynamics are important because they dictate shear stress and washout necessary to avoid stasis on TAV leaflets. Sinus flow is controlled by TAV axial deployment position but little is known regarding TAV axis misalignment effect. This study aims to elucidate TAV angular misalignment with respect to aortic root axis effect on sinus flow stasis potentially leading to leaflet thrombosis. Sinus hemodynamics were assessed in vitro using particle-image velocimetry in three different angular misalignments with respect to aorta axis: untilted, tilted away from the sinus and tilted towards sinus. A 26 mm Edwards SAPIEN3 was implanted in a 3D printed model of an anatomically realistic aortic root. TAV hemodynamics, sinus vortex tracking, leaflet shear stress probability density functions, and sinus blood time to washout were calculated. While pressure gradients differed insignificantly, blood velocity and vorticity decreased significantly in both tilted cases sinuses. Shear stress probability near the leaflet decreases with tilt indicating stasis. TAV tilted away from the sinus is the most unfavorable scenario with poor washout. TAV axial misalignment adds to factors list that could influence leaflet thrombosis risk through modifying sinus hemodynamics and washout.

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On the Mechanics of Transcatheter Aortic Valve Replacement

Cited by 74 publications

References 150 publications

Glycation and Serum Albumin Infiltration Contribute to the Structural Degeneration of Bioprosthetic Heart Valves

Glycation and Serum Albumin Infiltration Contribute to the Structural Degeneration of Bioprosthetic Heart Valves

Novel Polymeric Valve for Transcatheter Aortic Valve Replacement Applications: In Vitro Hemodynamic Study

Sinus Hemodynamics Variation with Tilted Transcatheter Aortic Valve Deployments

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