On the Modeling of Patient-Specific Transcatheter Aortic Valve Replacement: A Fluid–Structure Interaction Approach

Abstract

Purpose-Transcatheter aortic valve replacement (TAVR) is a minimally invasive treatment for high-risk patients with aortic diseases. Despite its increasing use, many influential factors are still to be understood and require continuous investigation. The best numerical approach capable of reproducing both the valves mechanics and the hemodynamics is the fluid-structure interaction (FSI) modeling. The aim of this work is the development of a patient-specific FSI methodology able to model the implantation phase as well as the valve working conditions during cardiac cycles. Methods-The patient-specific domain, which included the aortic root, native valve and calcifications, was reconstructed from CT images, while the CAD model of the device, metallic frame and pericardium, was drawn from literature data. Ventricular and aortic pressure waveforms, derived from the patient's data, were used as boundary conditions. The proposed method was applied to two real clinical cases, which presented different outcomes in terms of paravalvular leakage (PVL), the main complication after TAVR. Results-The results confirmed the clinical prognosis of mild and moderate PVL with coherent values of regurgitant volume and effective regurgitant orifice area. Moreover, the final release configuration of the device and the velocity field were compared with postoperative CT scans and Doppler traces showing a good qualitative and quantitative matching. Conclusion-In conclusion, the development of realistic and accurate FSI patient-specific models can be used as a support for clinical decisions before the implantation.

Pre-Operative Modeling of Transcatheter Mitral Valve Replacement in a Surgical Heart Valve Bioprosthesis

“…These assumptions can influence the resulting Von Mises stress distribution of the S3 device, although this study was mainly focused on the deformed shape of the deployed S3 THV rather than the resulting stress distribution. Although stress distributions at the mitral valve annulus were in agreement with those reported for the simulation of the transcatheter aortic valve implantation by our group [15] and those of other groups [20,25,[26][27][28][29], the heart and mitral valve annulus structure is complex and characterized by a heterogeneous, hyperplastic, and anisotropic material with limited knowledge of material descriptors and constitutive behavior. Figure 4A shows the deformed shape of TMVR as deployed on the bioprosthetic heart valve after numerical simulation.…”

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

“…In spite of such clinical studies, there is a very limited literature on the biomechanical implications of LVOT obstruction after TMVR. Most of computational studies on THV are related to transcatheter aortic valve implantation to determine the biomechanical interaction of the device with stenotic valve leaflets [23,24] as well as the assessment of the risk of paravalvular leakage [25,26]. In TMVR, Kohli and collaborators [27] performed a fluid-dynamic analysis where the prolonged THV was simulated by a rigid wall protrusion in the left ventricle and observed an increase in the flow velocity and pressure drop across the neoLVOT as here observed.…”

“…To our knowledge, this study is the first application of patient-specific model ing of TMVR to offer insights into the post-implantation hemodynamic and structural mechanics of left ventricle. The simulation of S3 Ultra deployment was based on finite-element analyses inspired by the mod eling of transcatheter aortic valve implantation and includes the presence of the expandable balloon and the fluid-cavity approach for a faithfully replicate of the clinical procedure [25,26]. The SPH method was successfully implemented to simulate the interaction between the blood flow and the S3 Ultra.…”

In-Silico Trials for Treatment of Acute Ischemic Stroke

“…By simulating the interaction between the stent-retrievers and the vessel wall, we will be able to assess the potential for tissue damage associated with the forces applied by the retriever during deployment and shear stress induced during the retrieving operation. These ISMs are be based on the established techniques of finite element modeling of stent-retrievers (37,38).…”