21 research outputs found
Performance hémodynamique de prothÚses valvulaires aortiques percutanées et stratégies d'implantation lors de procédures « valve-in-valve » : études in vitro et in vivo
"ThĂšse en cotutelle Doctorat en mĂ©decine expĂ©rimentale, UniversitĂ© Laval, QuĂ©bec, Canada, PhilosophiĂŠ doctor (Ph. D.), et Aix-Marseille UniversitĂ©, Marseille, France"Lâimplantation de prothĂšse valvulaire aortique percutanĂ©e (TAVI), a Ă©mergĂ© comme une alternative moins invasive que la chirurgie pour les patients avec stĂ©nose sĂ©vĂšre et haut risque chirurgical. Les rĂ©sultats prometteurs tant hĂ©modynamiques que cliniques du TAVI pourraient conduire Ă Ă©tendre ce traitement Ă une population de plus en plus large avec anatomie plus complexe ou risque chirurgical plus bas, ainsi quâaux patients avec bioprothĂšses chirurgicales (BPs) dĂ©gĂ©nĂ©rĂ©es. Cette derniĂšre application Ă©galement appelĂ©e « Valve-in-Valve » (ViV), consiste Ă implanter une prothĂšse percutanĂ©e dans une BP dĂ©faillante et permet dâĂ©viter la rĂ©intervention chirurgicale invasive associĂ©e Ă un risque de mortalitĂ© augmentĂ©. Cependant, deux complications hĂ©modynamiques majeures limitent la gĂ©nĂ©ralisation de ces techniques percutanĂ©es. Dans le contexte du TAVI « classique », il sâagit des fuites pĂ©rivalvulaires (PVL) dont la prĂ©sence est associĂ©e Ă une mortalitĂ© augmentĂ©e. Ces fuites pourraient ĂȘtre plus sĂ©vĂšres dans des anneaux non circulaires. Lâeffet du surdimensionnement de la prothĂšse percutanĂ©e, pour assurer son Ă©tanchĂ©itĂ©, sur lâhĂ©modynamie est mal connu et pourrait avoir un impact nĂ©gatif. De plus, les exigences en termes de performance hĂ©modynamique et de durabilitĂ© de la prothĂšse percutanĂ©e doivent ĂȘtre plus hautes chez une population Ă plus bas risque chirurgical. Il est donc important de dĂ©terminer la faisabilitĂ© du TAVI et de caractĂ©riser la performance hĂ©modynamique dans ces situations dâimplantation. Dans le contexte ViV, la prĂ©sence de hauts gradients (â„ 20 mmHg) post-procĂ©duraux est frĂ©quente et a Ă©tĂ© associĂ©e Ă une mortalitĂ© augmentĂ©e. Ces gradients Ă©levĂ©s, traduisent souvent une stĂ©nose rĂ©siduelle et sont particuliĂšrement frĂ©quents dans les BPs stĂ©nosĂ©es de taille nominale †21 mm. Les petites BPs et le mode de dĂ©gĂ©nĂ©rescence ont Ă©galement Ă©tĂ© associĂ©s Ă une mortalitĂ© augmentĂ©e. Ainsi, le ViV nâest pas indiquĂ© dans la plupart des petites BPs et par consĂ©quent, il nâexiste actuellement aucune recommandation pour leur traitement. Les facteurs que sont les petites BPs et le mode de dĂ©gĂ©nĂ©rescence actuellement mis en cause ne sont pas assez spĂ©cifiques et excluent trop de patients qui pourraient bĂ©nĂ©ficier du traitement. Par ailleurs, le bĂ©nĂ©fice hĂ©modynamique rĂ©el du ViV par rapport aux statuts avant ViV nâa pas Ă©tĂ© Ă©tudiĂ©. Il est donc nĂ©cessaire de prĂ©ciser les facteurs associĂ©s non seulement Ă la performance hĂ©modynamique post-ViV mais Ă©galement Ă lâutilitĂ© du traitement. iv Lâobjectif gĂ©nĂ©ral de ce travail doctoral est de comprendre les interactions entre la prothĂšse percutanĂ©e et lâanneau aortique ou la BP Ă traiter, impliquĂ©es dans la performance hĂ©modynamique, en particulier dans des conditions dâimplantation complexes, afin dâĂ©tendre les indications du TAVI. Dans le contexte ViV, le dĂ©fi est de prĂ©ciser les facteurs modifiables et non modifiables associĂ©s Ă la performance et Ă lâutilitĂ© hĂ©modynamiques du traitement, afin dâidentifier les patients susceptibles dâen bĂ©nĂ©ficier et de proposer des stratĂ©gies dâimplantation pour Ă©viter la stĂ©nose rĂ©siduelle.Transcatheter aortic valve implantation (TAVI) has emerged as a less invasive alternative to surgery for patients with severe aortic stenosis and high surgical risk. The promising hemodynamic and clinical outcomes after TAVI has led to extend indications to a larger population including patients with complex anatomy or lower surgical risk, as well as patients with degenerated surgical bioprostheses (BPs). The latter application of TAVI referred to as Valve-in-Valve (ViV) consists in implanting a transcatheter prosthesis within a failing BP in order to avoid redo surgery which is associated with an increased risk of mortality. However, generalization of transcatheter procedures remains limited by 2 major concerns. Regarding "classical" TAVI, the incidence of perivalvular leaks has been associated with increased risk of mortality and may be worsened in non circular annuli. Oversizing, which is used to secure the device, might have a negative impact on the prosthesis hemodynamics but its real effect is unknown. Moreover, the treatment of a lower risk and younger population requires excellent hemodynamic performance and valve durability. It is thus necessary to determine the feasibility of TAVI and to assess the hemodynamic performance in those complex situations. Regarding ViV implantations, the Achille's heel has been residual stenosis. Indeed, elevated post-procedural gradients are common following ViV, especially in BPs with label size †21 mm, and have been associated with increased mortality. However, there is only few experience in small BPs which are currently excluded from ViV indications and for which there is no recommendation. The factors that have been identified are not specific enough and ViV might be beneficial to a large proportion of patients which are currently excluded from indications. Besides, the actual hemodynamic benefit associated with ViV has not been evaluated (vs. pre ViV status). It is thus necessary to determine precisely the factors associated with both post-ViV hemodynamic performance and which treatment utility. The general objective of this work is to understand the interactions between the transcatheter prosthesis and the aortic annulus or the BP to be treated, which impact the hemodynamic performance, especially in complex conditions of implantation, in order to extend the indications of TAVI. In the context of ViV, the objective is to specify the modifiable and non-modifiable factors associated with the hemodynamic performance and utility of the treatment. The final aim is to identify patients who will benefit from ViV and to provide strategies of implantation in order to avoid residual stenosis
Hemodynamic performance of transcatheter aortic valve prostheses and strategie of implantation for valve-in-valve procedures : in vitro and in vivo studies
Lâimplantation valvulaire aortique percutanĂ©e (TAVI) a Ă©mergĂ© comme une alternative Ă la chirurgie pour les patients avec stĂ©nose sĂ©vĂšre et haut risque chirurgical. Cette technique sâĂ©tend Ă une population plus large (e.g. anatomie plus complexe, risque chirurgical plus bas), ainsi qu'au traitement Valve-in-Valve (ViV) des bioprothĂšses (BPs) chirurgicales dĂ©faillantes. Cependant, deux complications majeures en limitent la gĂ©nĂ©ralisation. En TAVI « classique », la prĂ©sence de fuites pĂ©ripothĂ©tiques a Ă©tĂ© associĂ©e Ă une mortalitĂ© augmentĂ©e. Les effets du surdimensionnement de la prothĂšse percutanĂ©e pour assurer son Ă©tanchĂ©itĂ©, ou de la forme de lâanneau souvent non circulaire, sur la performance hĂ©modynamique, sont mal connus. En ViV, la prĂ©sence de hauts gradients est frĂ©quente et associĂ©e Ă une mortalitĂ© augmentĂ©e. Les BPs de taille nominale †21 mm et le mode de dĂ©gĂ©nĂ©rescence par stĂ©nose, facteurs mis en cause dans la stĂ©nose rĂ©siduelle et associĂ©s Ă une mortalitĂ© augmentĂ©e, ne sont pas assez spĂ©cifiques et il nâexiste actuellement aucune recommandation pour le traitement des petites BPs. Par ailleurs, le bĂ©nĂ©fice hĂ©modynamique rĂ©el du ViV par rapport aux statuts avant ViV nâa pas Ă©tĂ© Ă©tudiĂ©.Lâobjectif gĂ©nĂ©ral de ce travail doctoral est de comprendre les interactions entre la prothĂšse percutanĂ©e et lâanneau aortique ou la BP Ă traiter, impliquĂ©es dans la performance hĂ©modynamique, en particulier dans des conditions dâimplantation complexes, afin dâĂ©tendre les indications du TAVI. En ViV, le dĂ©fi est de prĂ©ciser les facteurs associĂ©s Ă sa performance et son utilitĂ© hĂ©modynamique et de proposer des stratĂ©gies dâimplantation afin dâoptimiser le succĂšs de la procĂ©dure.Transcatheter aortic valve implantation (TAVI) has emerged as an alternative to surgery for patients with severe aortic stenosis and high surgical risk. This technique is extending to a wider population (e.g. with more complex anatomy or lower surgical risk), as well as to patients with degenerated surgical bioprostheses (BPs). However, two major concerns remain limiting. Regarding âclassical TAVIâ, periprosthetic leaks have been associated with increased mortality. Oversizing is used to secure the device within the aortic annulus which is often non circular. The effects of oversizing and annulus shape on the hemodynamic performance are unknown. Regarding ViV implantations, elevated post-procedural gradients are common and have been associated with increased mortality. The principal factors associated with this residual stenosis as well as with increased risk of mortality, have been BPs label size †21 mm and mode of failure by stenosis. These factors are not specific enough and there is currently no recommendation for the treatment of small BPs. Besides, the actual hemodynamic benefit associated with ViV has not been evaluated (vs. pre ViV status).The general objective of this work is to understand the interactions between the transcatheter prosthesis and the aortic annulus or the BP to be treated, which impact the hemodynamic performance, especially in complex conditions of implantation, in order to extend the indications of TAVI. In the context of ViV, the objective is to specify the factors associated with the hemodynamic performance and utility of the treatment. The final aim is to provide strategies of implantation in order to optimize the success of the procedure
Elastin-like polymer coating on CoCr surfaces for cardiovascular applications
Cardiovascular diseases have emerged as a major concern since they are the first cause of
death in developed countries. The advent of percutaneous transluminal coronary angioplasty
consisted in an alternative to invasive surgery. Especially the introduction of cardiovascular
stents has significantly meliorated the potential of angioplasty, e.g. with the use of drug
eluting and bioadsorbable stents. Still, restenosis remains a major implant-related
complication and can imply re intervention. Therefore, research has focused on limiting and/r
avoided restenosis by investigating the field of surface treatments and drug delivery material.
The rapidly developing field of material technology and engineering has enable design of
molecular-specific surfaces for a new generation of vascular devices. This project has been
focused on how to promote endothelialization on a bare metal CoCr alloy stent still widely
used nowadays. The knowledge about biological response and interactions between extra
cellular matrix proteins and cellular agents has lead to explore the potential of genetically
engineered protein based polymers such as elastin-like polymers which mimic properties of
the human elastin.
This project has for general goal to promote endothelialization on CoCr-alloy by
functionalizing the surfaces with REDV elastin-like biopolymer which contains a specific
domain for endothelial cell adhesion. For that purpose different surface treatments have been
performed on CoCr in order to enhance the biopolymer adhesion. First surfaces have been
activated by means of O2 plasma, acid HNO3 and NaOH basic etching. Afterwards, a series
has been CPTES silanized previous to biopolymer adsorption. Finally, REDV elastin-like
biopolymer has been physically and/or chemically attached to the different treated surfaces.
All treatments have been thoroughly physic-chemically characterized before and after all
treatments steps. Finally special attention has been paid to the study of biopolymer coating
stability after some thermal and/or mechanical treatments in order to determine the best
surface treatment conditions of adhesion and the efficiency of previous surface treatments.
REDV elastin-like biopolymer was successfully adsorbed on CoCr ASTM F-90 alloy surfaces.
It was biofunctionalized CoCr ASTM F-90 alloy surfaces through CPTES silane. Silanization
increased biopolymer adsorption but the efficiency was low. NaOH activated samples
presented a higher CPTES silane attachment and biopolymer adhesion as observed by an
increase of adhered HUVEC cells compared to other treatments.
REDV elastin-like biopolymer is more sensitive to mechanical and thermal treatments
probably due to a detachment and/or denaturation of the biomolecule. The increase of
silanization efficiency on treated CoCr surfaces could enhance biopolymer stability as
observed for NaOH treated surfaces.Incomin
Elastin-like polymer coating on CoCr surfaces for cardiovascular applications
Cardiovascular diseases have emerged as a major concern since they are the first cause of
death in developed countries. The advent of percutaneous transluminal coronary angioplasty
consisted in an alternative to invasive surgery. Especially the introduction of cardiovascular
stents has significantly meliorated the potential of angioplasty, e.g. with the use of drug
eluting and bioadsorbable stents. Still, restenosis remains a major implant-related
complication and can imply re intervention. Therefore, research has focused on limiting and/r
avoided restenosis by investigating the field of surface treatments and drug delivery material.
The rapidly developing field of material technology and engineering has enable design of
molecular-specific surfaces for a new generation of vascular devices. This project has been
focused on how to promote endothelialization on a bare metal CoCr alloy stent still widely
used nowadays. The knowledge about biological response and interactions between extra
cellular matrix proteins and cellular agents has lead to explore the potential of genetically
engineered protein based polymers such as elastin-like polymers which mimic properties of
the human elastin.
This project has for general goal to promote endothelialization on CoCr-alloy by
functionalizing the surfaces with REDV elastin-like biopolymer which contains a specific
domain for endothelial cell adhesion. For that purpose different surface treatments have been
performed on CoCr in order to enhance the biopolymer adhesion. First surfaces have been
activated by means of O2 plasma, acid HNO3 and NaOH basic etching. Afterwards, a series
has been CPTES silanized previous to biopolymer adsorption. Finally, REDV elastin-like
biopolymer has been physically and/or chemically attached to the different treated surfaces.
All treatments have been thoroughly physic-chemically characterized before and after all
treatments steps. Finally special attention has been paid to the study of biopolymer coating
stability after some thermal and/or mechanical treatments in order to determine the best
surface treatment conditions of adhesion and the efficiency of previous surface treatments.
REDV elastin-like biopolymer was successfully adsorbed on CoCr ASTM F-90 alloy surfaces.
It was biofunctionalized CoCr ASTM F-90 alloy surfaces through CPTES silane. Silanization
increased biopolymer adsorption but the efficiency was low. NaOH activated samples
presented a higher CPTES silane attachment and biopolymer adhesion as observed by an
increase of adhered HUVEC cells compared to other treatments.
REDV elastin-like biopolymer is more sensitive to mechanical and thermal treatments
probably due to a detachment and/or denaturation of the biomolecule. The increase of
silanization efficiency on treated CoCr surfaces could enhance biopolymer stability as
observed for NaOH treated surfaces.Incomin
Hemodynamic performance of transcatheter aortic valve prostheses and strategie of implantation for valve-in-valve procedures : in vitro and in vivo studies
Lâimplantation valvulaire aortique percutanĂ©e (TAVI) a Ă©mergĂ© comme une alternative Ă la chirurgie pour les patients avec stĂ©nose sĂ©vĂšre et haut risque chirurgical. Cette technique sâĂ©tend Ă une population plus large (e.g. anatomie plus complexe, risque chirurgical plus bas), ainsi qu'au traitement Valve-in-Valve (ViV) des bioprothĂšses (BPs) chirurgicales dĂ©faillantes. Cependant, deux complications majeures en limitent la gĂ©nĂ©ralisation. En TAVI « classique », la prĂ©sence de fuites pĂ©ripothĂ©tiques a Ă©tĂ© associĂ©e Ă une mortalitĂ© augmentĂ©e. Les effets du surdimensionnement de la prothĂšse percutanĂ©e pour assurer son Ă©tanchĂ©itĂ©, ou de la forme de lâanneau souvent non circulaire, sur la performance hĂ©modynamique, sont mal connus. En ViV, la prĂ©sence de hauts gradients est frĂ©quente et associĂ©e Ă une mortalitĂ© augmentĂ©e. Les BPs de taille nominale †21 mm et le mode de dĂ©gĂ©nĂ©rescence par stĂ©nose, facteurs mis en cause dans la stĂ©nose rĂ©siduelle et associĂ©s Ă une mortalitĂ© augmentĂ©e, ne sont pas assez spĂ©cifiques et il nâexiste actuellement aucune recommandation pour le traitement des petites BPs. Par ailleurs, le bĂ©nĂ©fice hĂ©modynamique rĂ©el du ViV par rapport aux statuts avant ViV nâa pas Ă©tĂ© Ă©tudiĂ©.Lâobjectif gĂ©nĂ©ral de ce travail doctoral est de comprendre les interactions entre la prothĂšse percutanĂ©e et lâanneau aortique ou la BP Ă traiter, impliquĂ©es dans la performance hĂ©modynamique, en particulier dans des conditions dâimplantation complexes, afin dâĂ©tendre les indications du TAVI. En ViV, le dĂ©fi est de prĂ©ciser les facteurs associĂ©s Ă sa performance et son utilitĂ© hĂ©modynamique et de proposer des stratĂ©gies dâimplantation afin dâoptimiser le succĂšs de la procĂ©dure.Transcatheter aortic valve implantation (TAVI) has emerged as an alternative to surgery for patients with severe aortic stenosis and high surgical risk. This technique is extending to a wider population (e.g. with more complex anatomy or lower surgical risk), as well as to patients with degenerated surgical bioprostheses (BPs). However, two major concerns remain limiting. Regarding âclassical TAVIâ, periprosthetic leaks have been associated with increased mortality. Oversizing is used to secure the device within the aortic annulus which is often non circular. The effects of oversizing and annulus shape on the hemodynamic performance are unknown. Regarding ViV implantations, elevated post-procedural gradients are common and have been associated with increased mortality. The principal factors associated with this residual stenosis as well as with increased risk of mortality, have been BPs label size †21 mm and mode of failure by stenosis. These factors are not specific enough and there is currently no recommendation for the treatment of small BPs. Besides, the actual hemodynamic benefit associated with ViV has not been evaluated (vs. pre ViV status).The general objective of this work is to understand the interactions between the transcatheter prosthesis and the aortic annulus or the BP to be treated, which impact the hemodynamic performance, especially in complex conditions of implantation, in order to extend the indications of TAVI. In the context of ViV, the objective is to specify the factors associated with the hemodynamic performance and utility of the treatment. The final aim is to provide strategies of implantation in order to optimize the success of the procedure
Mitral bileaflet mechanical heart valves dysfunction and patient/prosthesis mismatch: in vitro investigation of differential diagnosis
International audienc
Effects of Hemodynamic Conditions and Valve Sizing on Leaflet Bending Stress in SelfâExpanding Transcatheter Aortic Valve: An Inâvitro Study
International audienc
EFFECT OF VALVE OVERSIZING ON LEAFLET BENDING STRESS IN THE COREVALVE: AN IN VITRO STUDY
66th Annual Scientific Session and Expo of the American-College-of-Cardiology (ACC), Washington, DC, MAR 17-19, 2017International audienceno abstrac
Impact of vascular hemodynamics on aortic stenosis evaluation : new insights into the pathophysiology of normal flow - small aortic valve area - low gradient pattern
Background:
About 50% of normalâflow/lowâgradient patients (ie, low mean gradient [MG] or peak aortic jet velocity and small aortic valve area) have severe aortic valve calcification as measured by computed tomography. However, they are considered to have moderate aortic stenosis (AS) in current American College of Cardiology/American Heart Association guidelines. The objective was thus to evaluate the effect of hypertension and reduced arterial compliance (rAC) on MG and Vpeak measurements.
Methods and Results:
Dopplerâechocardiography was performed in 4 sheep with experimentally induced severe and critical AS at: (1) normal aortic pressure, (2) during hypertension, and (3) with rAC. Hypertension and rAC induced a substantial decrease in MG/Vpeak compared with normal stage (both Pâ€0.03) despite a stable transvalvular flow (P>0.16). Hypertension and rAC resulted in a greater reduction of MG in critical (â42%) compared with severe (â35%) AS (PË0.0001). Comprehensive Dopplerâechocardiography and computed tomography were performed in 220 AS patients (mean age: 69±13 years; MG 29±18 mm Hg) with normal flow. The population was divided in 3 groups according to the presence of hypertension and rAC. The slope of the linear association between MG/Vpeak and aortic valve calcification divided by the crossâsectional area of the aortic annulus was significantly reduced in patients with hypertension and/or rAC compared with normotensive/normal AC patients (P<0.01). Accordingly, patients with normalâflow/lowâgradient and severe aortic valve calcification density were more frequent in hypertension and rAC groups compared with the normotensive/normalâAC group (16% and 12% compared with 2%; P=0.03).
Conclusions:
Hypertension and rAC are associated with a substantial reduction in MG/Vpeak for similar aortic valve calcification (ie, similar AS anatomic severity), which may lead to underestimation of AS hemodynamic severit
Effect of oversizing and elliptical shape of aortic annulus on transcatheter valve hemodynamics: An in vitro study
International audienceBackground: Transcatheter aortic valve implantation (TAVI) is often performed in patients with non-circular aortic annulus and in oversizing (OS) conditions. The impact of elliptical annulus shape and the consequences of oversizing/underdeployment on the hemodynamic performance are still debated. Objective: This in-vitro study aims to assess and compare the valve hemodynamic performances of the Edwards SAPIEN transcatheter heart valve (THV) in the different current conditions of use: important oversizing in small circular annuli and in elliptical annuli, moderate oversizing in circular and in elliptical annuli of various degrees of eccentricity. Methods: A pulsed cardiovascular simulator was used. Edwards SAPIEN 23 and 26 (mm) were implanted in different circular and elliptical annuli of various sizes and eccentricity. Transvalvular mean pressure gradients (TPGm), effective orifice area (EOA) after implantation of Edwards SAPIEN THV were measured by Dopplere-chocardiography and the performance index (PI - 100 x EOA / Annulus Area) was calculated. Para and transvalvular regurgitation was assessed by color-Doppler and leakage volume was quantified by flowmeter measurement. Results: For a given aortic annulus area, EOAs after implantation of Edwards SAPIEN THV were generally larger and TPGms lower with elliptical annuli compared to circular annuli. The PI was higher (p = 0.047) for elliptical (48 +/- 3%) than for circular annuli (43 +/- 5%). Paravalvular regurgitation occurred only in the case of the SAPIEN 26 implanted in the elliptical annulus with highest eccentricity. Conclusion: The results of this in-vitro study suggest that the EOAs of Edwards SAPIEN are better in elliptical than in circular annuli. No transvalvular regurgitation occurred and only one paravalvular regurgitation was observed after implantation of SAPIEN 26 in the highly eccentric annulus. (C) 2016 Elsevier Ireland Ltd. All rights reserved