Performance hémodynamique de prothèses valvulaires aortiques percutanées et stratégies d'implantation lors de procédures « valve-in-valve » : études in vitro et in vivo

Authors: Zenses, Anne-Sophie
Advisor: Pibarot, Philippe; Rieu, Régis
Abstract: 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.
Document Type: Thèse de doctorat
Issue Date: 2018
Open Access Date: 25 January 2019
Grantor: Université Laval
Collection:Thèses et mémoires

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