The Fluid Mechanics of Transcatheter Heart Valve Leaflet Thrombosis in the Neosinus

Midha, Prem A.; Raghav, Vrishank; Sharma, Rahul; Condado, José F.; Okafor, Ikechukwu; Rami, Tanya; Kumar, Gautam; Thourani, Vinod H.; Jilaihawi, Hasan; Babaliaros, Vasilis; Makkar, Raj; Yoganathan, Ajit P.

doi:10.1161/circulationaha.117.029479

Cited by 177 publications

(147 citation statements)

References 33 publications

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“…1a), not allowing the formation of strong enough recirculation zone in the sinuses to assist a faster closing of the leaflets. 23 This design feature will be addressed accordingly in the next design iteration.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

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

et al. 2018

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“…For the pre‐TAVR measurements, the aortic annulus was defined as the virtual plane connecting the basal insertion points of the three aortic valve leaflets . Since the leaflets are not visible on post‐TAVR data, the annular plane was defined by the plane that intersects the bottom of all three aortic sinuses . In both the pre‐TAVR and post‐TAVR measurements, the following planes were defined perpendicular to the centerline: the LVOT plane was defined 4 mm below the annulus; the sinus plane was defined at the largest dimension of the sinus of Valsalva (SOV), the STJ was defined as the plane connecting the points at which the SOV transitions to the ascending aorta; and the ascending aorta plane was defined at 10 mm above the STJ.…”

Section: Methodsmentioning

confidence: 99%

“…7 Though some studies have shown higher longterm survival rates in patients with increased surgical risk who undergo TAVR versus surgery, 4 complications including subclinical thrombus formation, paravalvular leakage, prosthesis migration/embolization, stroke, permanent pacemaker, and coronary occlusion have motivated numerous in vitro and in silico studies to provide greater understanding and improve clinical practice. [8][9][10][11][12][13][14][15][16] To facilitate further research and investigation into the hemodynamic profiles of the post-TAVR aortic root, a greater understanding of how aortic root geometry changes after TAVR is imperative. Current research utilizes a heterogeneous mix of aortic root geometries of healthy patients, untreated AS patients and patients that have been indicated for TAVR.…”

Section: Introductionmentioning

confidence: 99%

Characterization of aortic root geometry in transcatheter aortic valve replacement patients

Madukauwa-David

Midha

Sharma³

et al. 2018

Cathet Cardio Intervent

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Purpose The study aimed to characterize the geometry of the aortic root pre‐ and post‐transcatheter aortic valve replacement (TAVR) and investigate differences in pre‐ and post‐TAVR anatomy. Background A greater understanding of how aortic root geometry changes after TAVR is needed to facilitate further investigation into the hemodynamic profiles of the post‐TAVR aortic root. Methods Anatomical measurements were conducted on de‐identified, retrospective post‐TAVR 4DCT scans of 109 patients with aortic stenosis obtained from the RESOLVE study. The diameter of the aortic root was measured at the level of the annulus, left ventricular outflow tract (LVOT), sinus of Valsalva, sinotubular junction (STJ) and ascending aorta. The heights of the STJ and coronary arteries were also measured. Results All aortic root dimensions were normally distributed across the cohort and changed significantly between pre‐ and post‐TAVR conditions (P < 0.01). Post‐TAVR dimensions changed significantly from peak systole to end diastole (P < 0.01). Regression models were obtained for all aortic root dimensions in terms of annulus diameter with excellent coefficient of determination (R2 > 0.95, P < 0.001). Conclusions There are significant differences between pre‐ and post‐TAVR as well as peak systolic and end diastolic aortic root anatomy. Appropriate anatomical dimensions should be selected for benchtop testing as the geometry varies greatly throughout the cardiac cycle.

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“…As a result, in vitro experimental testing such as the one presented in this study can be used to validate and verify the computational simulations (46)(47)(48)(49). The geometric confinement of TAVs disturbs the natural flow field between the leaflets and aortic sinuses, increases the blood residence time (stasis) on the leaflets, and consequently increases the likelihood of thrombogenesis on the TAV leaflets (58)(59)(60)(61)(62). For instance, regions of blood stagnation provide an opportunity for platelets and blood proteins to accumulate to critical concentrations leading to thrombosis (50)(51)(52)(53)(54)(55)(56)(57).…”

Section: Discussionmentioning

confidence: 91%

Fluid Dynamic Characterization of Transcatheter Aortic Valves Using Particle Image Velocimetry

2018

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Transcatheter aortic valves provide superior systolic hemodynamic performance in terms of valvular pressure gradient and effective orifice area compared with equivalent size surgical bioprostheses. However, in depth investigation of the flow field structures is of interest to examine the flow field characteristics and provide experimental evidence necessary for validation of computational models. The goal of this study was to compare flow field characteristics of the three most commonly used transcatheter and surgical valves using phase-locked particle image velocimetry (PIV). 26-mm Edwards SAPIEN 3, 26-mm Medtronic CoreValve, and 25-mm Carpentier-Edwards PERIMOUNT Magna were examined in a pulse duplicator with input parameters matching ISO-5840, that is, heart rate of 70 beats/min, cardiac output of 5 L/min, and mean aortic pressure of 100 mm Hg. A 2D PIV system was used to obtain flow velocity and viscous shear stress fields during the entire cardiac cycle. In vitro testing showed that the mean transvalvular pressure gradient was lowest for SAPIEN 3, followed by CoreValve, and PERIMOUNT Magna surgical bioprosthesis. In addition, the viscous shear stress magnitude within the jet boundary layer was higher in PERIMOUNT Magna than CoreValve and SAPIEN 3 at the peak of the flow. However, the measured shear stress values were below the known threshold for platelet activation and red blood damage. Therefore, shear-induced platelet activation is unlikely to take place during systole in the three bioprosthetic heart valves. The PIV measurements can be used for verification and validation of computational simulations.

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The Fluid Mechanics of Transcatheter Heart Valve Leaflet Thrombosis in the Neosinus

Cited by 177 publications

References 33 publications

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

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

Characterization of aortic root geometry in transcatheter aortic valve replacement patients

Fluid Dynamic Characterization of Transcatheter Aortic Valves Using Particle Image Velocimetry

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