Simulation of left ventricular outflow tract (LVOT) obstruction in transcatheter mitral valve-in-ring replacement

Abstract

Left ventricular outflow tract (LVOT) obstruction is a feared complication of transcatheter mitral valve replacement (TMVR). This procedure leads to an elongation of LVOT in the left ventricle (namely, the neoLVOT), ultimately portending hemodynamic impairment and death. This study sought to understand the biomechanical implications of LVOT obstruction in two patients who underwent TMVR as an "off-label" application of the Edwards SAPIEN 3 (S3) Ultra transcatheter heart valve (THV). A computational framework of TMVR was developed to assess the neoLVOT area and quantify the sub-aortic flow structure. We observed that the annuloplasty ring serves as the key anchor zone of S3 Ultra THV. A good agreement was found between the numerically-predicted and CT-imaging measurements of neoLVOT area, with differences less than 10% in both patients. The pressure drop across the neoLVOT did not determine hemodynamic impairment in both patients. Quantification of structural and hemodynamic variables by computational modeling may facilitate more accurate predictions of the LVOT obstruction in TMVR, particularly for patients which are considered to have a borderline risk of obstruction

Patient-specific fluid simulation of transcatheter mitral valve replacement in mitral annulus calcification

“…The principal aim of the current study is to evaluate whether computation fluid dynamics can provide patient specific physiological models of ViMAC and thereby predictions of anticipated left ventricular outflow tract gradients from preprocedural multiphase gated CT scans. The secondary aim was to explore whether blood flow biomarkers from the models could be used to evaluate prothrombotic conditions on the underside of bioprosthetic mitral valve leaflets ( 28 – 31 ).…”

A toolbox for generating scalable mitral valve morphometric models

“…While the first approach is time consuming, requiring extensive pre-processing to reconstruct the MV shape of a subject and define patient-specific modelling properties, the second approach is faster, arising as one step forward towards the clinical translation of MV models. Recent parameterization frameworks include the 2D mapping of leaflet surfaces from imaging modalities for a more intuitive detection of pathology during decision making (Lichtenberg et al, 2020), the creation of 3D MV shapes from specific measurements performed in imaging modalities and their use to study the effect of transcatheter MV replacement in left ventricular outflow tract haemodynamics (Pasta et al, 2020), and a heuristic generation of chordae tendineae and PM tips (Walczak et al, 2021). While these frameworks are able to quickly generate clinically relevant MV shapes, they can only be applied to individual cases.…”

“…Some parametric MV models lack the anatomical detail that is necessary to be of clinical value, including only a simplistic representation of the leaflets (Salgo et al, 2002, Shen et al, 2017, Domenichini and Pedrizzetti, 2015. Other studies have included more complete parametric geometries including chordae tendineae and PM tips (Choi et al, 2016, Alleau et al, 2019, while more advanced parameterization frameworks have been recently developed to generate patient-specific MV surface models from measurements obtained via medical imaging (Lichtenberg et al, 2020, Pasta et al, 2020. While these advanced frameworks can generate high quality MV models within a reasonable time frame, they can only be applied to each specific patient individually, not offering the flexibility required to allow for the evaluation of how specific dimensions of MV geometry affects its function, for example.…”

Numerical simulation of transcatheter mitral valve replacement: The dynamic implication of LVOT obstruction in the valve-in-ring case

“…In accordance with mitral annulus geometry of LHHM, the S3 Ultra with diameter of 23 mm was used in this study. Specifically, the S3 Ultra stent frame was modeled using micro-CT images and then meshed with nearly 60,000 structured hexahedral solid elements with reduced integration and hourglass control (Pasta et al, 2020a;Pasta et al, 2020b). To avoid mesh distortion and ensure solution convergence, the THV skirt was modeled after the crimping phase by closing the device frame cells at mid-thickness of the S3 frame geometry (Fig.…”