Effect of oversizing and elliptical shape of aortic annulus on transcatheter valve hemodynamics: An in vitro study

Salaün, Erwan; Zenses, Anne‐Sophie; Evin, Morgane; Collart, Frédéric; Habib, Gilbert; Pîbarot, Philippe; Rieu, Régis

doi:10.1016/j.ijcard.2016.01.048

Cited by 21 publications

(17 citation statements)

References 29 publications

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“…We observed that the aspect ratio of the annulus lumen increases during diastolic phases and decreases during the systolic phases (10% to 30%). The largest difference was between 10% and 70%, which confirms previous findings [ 24 , 34 ] that the annulus remains elliptical during the whole cardiac cycle.…”

Section: Discussionsupporting

confidence: 91%

Dynamics of the aortic annulus in 4D CT angiography for transcatheter aortic valve implantation patients

et al. 2017

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BackgroundTranscatheter aortic valve implantation (TAVI) is a well-established treatment for patients with severe aortic valve stenosis. This procedure requires pre-operative planning by assessment of aortic dimensions on CT Angiography (CTA). It is well-known that the aortic root dimensions vary over the heart cycle. However, sizing is commonly performed at either mid-systole or end-diastole only, which has resulted in an inadequate understanding of its full dynamic behavior.Study goalWe studied the variation in annulus measurements during the cardiac cycle and determined if this variation is dependent on the amount of calcification at the annulus.MethodsWe measured and compared aortic root annular dimensions and calcium volume in CTA acquisitions at 10 cardiac cycle phases in 51 aortic stenosis patients. Sub-group analysis was performed based on the volume of calcium by splitting the population into mildly and severely calcified valves subgroups.ResultsFor most annulus measurements, the largest differences were found between 10% and 70 to 80% cardiac cycle phases. Mean difference (±standard deviation) in annular minimum diameter, maximum diameter, area, and aspect ratio between mid-systole and end-diastole phases were 1.0 ± 0.29 mm (p = 0.065), 0.30 ± 0.24 mm (p = 0.7), 24.1 ± 7.6 mm2 (p < 0.001), and 0.041 ± 0.012 (p = 0.039) respectively. Calcium volume measurements varied strongly during the cardiac cycle. The dynamic annulus area was behaving differently between mildly and severely calcified subgroups (p = 0.02). Furthermore, patients with severe aortic calcification were associated with larger annulus diameters.ConclusionThere is a significant variation of annulus area and calcium volume measurement during the cardiac cycle. In our measurements, only the dynamic variation of the annulus area is dependent on the severity of the aortic calcification. For TAVI candidates, the annulus area is significantly larger in mid-systole compared to end-diastole.

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Section: Discussionsupporting

confidence: 91%

Dynamics of the aortic annulus in 4D CT angiography for transcatheter aortic valve implantation patients

et al. 2017

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“…To our best knowledge, this study is the first to systematically analyze the impact of abnormal TAV deployment on the valve hemodynamics using an integrated computational and experimental approach. Although the effect of ellipticity and under‐expanded deployment of TAVs on valvular hemodynamics has been studied previously by in vitro experiments , some of these studies have shown contradictory results due to the lack of parametric control. A study found that the circular valve had a lower mean TPG compared with the elliptical valve for the test condition of 5 L/min CO (6.9 vs. 8.0 mm Hg).…”

Section: Discussionmentioning

confidence: 99%

“…Again, our results agree with the experimental observations. Salaun et al investigated the effect of oversizing and elliptical shape on Edwards SAPIEN valves. They found that for a given aortic annulus area, mean TPGs were generally lower with elliptical annuli compared to circular annuli.…”

Section: Discussionmentioning

confidence: 99%

Simulated Transcatheter Aortic Valve Flow: Implications of Elliptical Deployment and Under‐Expansion at the Aortic Annulus

Sirois

Mao

et al. 2018

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Clinical use of transcatheter aortic valves (TAVs) has been associated with abnormal deployment, including oval deployment and under-expansion when placed into calcified aortic annuli. In this study, we performed an integrated computational and experimental investigation to quantify the impact of abnormal deployment at the aortic annulus on TAV hemodynamics. A size 23 mm generic TAV computational model, developed and published previously, was subjected to elliptical deployment at the annulus with eccentricity levels up to 0.68 and to under-expansion of the TAV at the annulus by up to 25%. The hemodynamic performance was quantified for each TAV deployment configuration. TAV opening geometries were fabricated using stereolithography and then subjected to steady forward flow testing in accordance with ISO-5840. Centerline pressure profiles were compared to validate the computational model. Our findings show that slight ellipticity of the TAV may not lead to degeneration of hydrodynamic performance. However, under large ellipticity, increases in transvalvular pressure gradients were observed. Under-expanded deployment has a much greater negative effect on the TAV hemodynamics compared with elliptical deployment. The maximum turbulent viscous shear stress (TVSS) values were found to be significantly larger in under-expanded TAVs. Although the maximum value of TVSS was not large enough to cause hemolysis in all cases, it may cause platelets activation, especially for under-expanded deployments.

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“…The annuli tested in this study had "ideal circular contours". In vivo, bicuspid valve phenotype and presence of calcification nodules at the level of aortic annulus often yields to non-circular [29] and irregular annulus cross-sectional shape, which may be associated with increased leaflet mechanical stress, and therefore reduced long-term durability of the TAV. In addition, the CoreValve was tested only in the supra-annular position as recommended clinically, and not in intra-annular or high supra-annular position, which could also have an effect on the valve deployment and the leaflet bending stress.…”

Section: Study Limitationsmentioning

confidence: 99%

Effects of hemodynamic conditions and valve sizing on leaflet bending stress in self‐expanding transcatheter aortic valve: An in vitro study

et al. 2020

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Objectives:Transcatheter aortic valve (TAV) replacement has become a viable alternative to surgery for high and intermediate risk patients with severe aortic stenosis. This technology may extend to the younger and lower risk patients. In this population, long-term durability of the TAV is key. Increased leaflet mechanical stress is one of the main determinants of valve structural deterioration. This in vitro study aims at evaluating, leaflet bending stress (LBS) in the selfexpanding TAV for different valve sizes, stroke volumes (SV) and degrees of valve oversizing (OS). Methods:Three different sizes (23, 26, 29 mm) of CoreValve (CV) were tested on a pulse duplicator in annulus size ranging from 17 to 26 mm. Leaflet bending stress and bending of the leaflet coaptation line in diastole (pin-wheeling index) were measured using high-speed camera imaging (1000 images/sec). Results:For each given CV and annulus size, geometric orifice area increased significantly with OS (p<0.001) and SV (p=0.001). LBS decreased with increasing prosthesis size and aortic annulus (AA) size while increasing with SV(p<0.03). The largest value of peak LBS (3.79 MPa) was obtained with the CV 23 mm in AA of 17 mm (%OS=35%), SV 90 ml and the smallest value (0.99 MPa) for the CV 29 mm in AA of 26 mm (%OS=12%), SV 30 ml. On multivariable analysis, LBS increased independently with larger OS, smaller AA size and higher SV. The pinwheeling index increased with decreasing AA size and increasing OS. Conclusions:Moderate valve OS, such as generally used for transcatheter aortic valve implantation, is associated with increased LBS during valve opening and closing, especially in small annuli. Hence, TAV OS may negatively impact long-term valve durability.

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Effect of oversizing and elliptical shape of aortic annulus on transcatheter valve hemodynamics: An in vitro study

Cited by 21 publications

References 29 publications

Dynamics of the aortic annulus in 4D CT angiography for transcatheter aortic valve implantation patients

Dynamics of the aortic annulus in 4D CT angiography for transcatheter aortic valve implantation patients

Simulated Transcatheter Aortic Valve Flow: Implications of Elliptical Deployment and Under‐Expansion at the Aortic Annulus

Effects of hemodynamic conditions and valve sizing on leaflet bending stress in self‐expanding transcatheter aortic valve: An in vitro study

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