Conference Agenda

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Session Overview
Session
S5: MS06 - 2: Cardiovascular Fluid-Structure Interaction: Advances, Challenges, and Clinical Impact
Time:
Wednesday, 10/Sept/2025:
9:00am - 10:20am

Session Chair: Francesco Viola
Location: Room CB26A


External Resource: https://iccb2025.org/programme/mini-symposia
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Presentations
9:00am - 9:20am

Fluid-Structure Interaction modeling of ascending aortic aneurysms with patient-specific material properties

S. Nocerino1, C. Catalano2, S. Zambon1, K. Calò1, S. Pasta2, U. Morbiducci1, D. Gallo1

1Politecnico di Torino, Italy; 2Università degli Studi di Palermo, Italy

Introduction

Biomechanical stimuli are crucial in the progression of ascending thoracic aortic aneurysm (ataa) [1,2,3]. Currently, biomechanical stimuli are typically obtained in silico through computational models. However, debate remains regarding computational fluid dynamics (cfd) and computational solid mechanics (csm) simulations due to (i) modeling assumptions and incomplete/uncertain input data derived from clinical sources and (ii) the complex interplay between hemodynamic and structural stresses, which is often overlooked. This study introduces a semi-automatic fluid-structure interaction (fsi) framework that integrates the identification of patient-specific aortic wall material properties, aiming at minimizing a primary source of uncertainty while enabling a comprehensive assessment of aortic biomechanics.

Methods

Aortic geometries, including the valve orifice plane, aortic root, and supra-aortic vessels, are reconstructed at peak systole and at end-diastole from retrospectively-gated computed tomography angiography (cta) [2]. Patient-specific transaortic jet velocity measured by Doppler echocardiography and pressure data obtained through brachial cuff measurements are used as input data. The vessel wall is modeled as a nonlinear isotropic hyperelastic Neo-Hookean solid with uniform thickness. To find patient-specific material properties, a simple iterative approach is adopted, using the ascending aorta (aao) measured systolic volume as target value for the calibration. After obtaining the diastolic tensional state through prestress simulations [4], the patient-specific systolic blood pressure is applied to the aortic wall in csm simulations. Young’s modulus is varied iteratively bisecting the initial interval 0.8-8.0 MPa [3] until the simulated aao systolic volume matches the measured target value within a 1% error. Following a prestress simulation using the previously estimated Young’s modulus, fsi simulations are conducted with a two-way arbitrary Lagrangian-Eulerian (ale) formulation. Homogeneous Dirichlet conditions are applied at the ring-shaped solid domain boundary sections in terms of null displacement. Doppler-derived flow rates are imposed in terms of flat velocity profile at the fluid inflow section. Zero-dimensional (0d) models are coupled to the 3d fluid domain outflow sections. The 0d parameters are tuned to match patient-specific cuff pressures in coupled 0d and one-dimensional (1d) simulations. All simulations are performed using the finite element-based solver SimVascular.

Results and discussion

For a representative patient, the aao peak systolic volume measured from cta was 107.60 cm³, leading to an estimated Young’s modulus of 2.15 MPa. The fsi simulation was able to capture the flow impingement region located in the anteromedial area of the bulge, where the highest values of time-averaged wall shear stress (tawss) were recorded, along with the greatest variation in wss contraction and expansion action on the luminal surface along the cardiac cycle.

By reconstructing the valve orifice, the fsi framework allows to simulate both tricuspid and bicuspid valve morphologies. This framework enables the exploration of the synergistic action of hemodynamic and structural stress, potentially revealing distinct or combined effects of these biomechanical stimuli on ataa progression.

References

  1. De Nisco et al., Med Eng Phys, 2020.

  2. Pasta et al., Ann Thorac Surg, 2020.

  3. Trabelsi et al., Ann Biomed Eng, 2016.

  4. Bäumler et al., Biomech Model Mechanobiol, 2020.



9:20am - 9:40am

Fluid–structure–electrophysiology interaction in the left heart: exploring turbulent flow dynamics for data-driven applications

F. Guglietta1,2, M. A. Scarpolini3,2, F. Viola3, L. Biferale1,2

1Tor Vergata University of Rome, Rome, Italy; 2INFN Tor Vergata, Rome, Italy; 3Gran Sasso Science Institute (GSSI), L'Aquila, Italy

Accurately capturing the dynamics of blood flow, pressure distribution, and structural deformation within the human heart is essential for advancing our understanding of cardiovascular physiology and for improving the diagnosis and monitoring of heart disease. However, direct in-vivo measurements remain challenging: they are often invasive, limited in spatial and temporal resolution, and constrained by technical and ethical considerations. In this context, patient-specific digital twins (i.e., computational models that can reproduce individual cardiovascular anatomy and function) have emerged as a powerful tool for simulating the cardiac cycle with high fidelity.

In this work, we employ our in-house, multi-GPU simulation framework [1], designed to capture the full complexity of cardiac mechanics through a tightly integrated Fluid–Structure–Electrophysiology Interaction (FSEI) formulation. This framework incorporates a biophysically detailed electrophysiology model to simulate myocardial activation via a physiologically-informed conduction system. It also features anatomically realistic mitral and aortic valves, enabling accurate simulation of valve dynamics throughout the cardiac cycle.

A key component of our approach is the integration of patient-specific anatomical data, typically acquired at discrete time points during the cardiac cycle. These data are assimilated into the simulation to personalize the digital twin, ensuring that it reflects the subject’s unique geometry and boundary conditions. To validate this approach and evaluate its sensitivity to physiological variability, we use the full FSEI model as a reference, allowing us to assess both the realism and robustness of the personalized simulations.

To probe the complexity of intraventricular flow, we carry out a detailed Lagrangian analysis based on passive tracer dynamics. By computing statistical quantities such as structure functions, flatness, and temporal correlation functions, we characterize the multiscale features of turbulence within the left heart.
Our results show that both ventricle and aorta are marked by strong intermittency and long-lasting flow structures. We further explore how these flow characteristics are influenced by physiological parameters, including heart rate and aortic valve stiffness. Specifically, we find that a lower heart rate enhances flow intermittency by allowing coherent structures to develop and persist, while increased valve stiffness amplifies extreme fluctuations.

Overall, this study demonstrates the effectiveness of Lagrangian diagnostics in capturing the spatial and temporal complexity of cardiac flows. Our findings contribute to a deeper understanding of cardiovascular hemodynamics and highlight the potential of combining high-performance computing with clinical data to develop predictive, patient-specific digital twins of the heart.

This research was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme Smart-TURB (Grant Agreement No. 882340), and by the project MUR-FARE R2045J8XAW.

[1] Viola et al., Scientific Reports, 13(1) (2023).



9:40am - 10:00am

G-effect on the performance of lymphatic valve to prevent reflux

A. Bou Orm, B. Kaoui

université de Technologie de Compiègne, France

We examine how gravity affects bicuspid valves designed to prevent backflow in lymphatic vessels—an area with limited research. The study focuses on environments with varying gravitational conditions, such as microgravity during space missions and parabolic flights, or hypergravity during fighter flights. Computer simulations were conducted while varying both gravity intensity and valve length to verify valve performance. Results show that valve effectiveness is influenced by both gravity and valve length, with longer valves performing better—though this is moderated by gravitational force. These findings offer valuable insights into valve efficiency in biofluid pumping under non-standard Earth gravity conditions.



10:00am - 10:20am

Hemodynamic effects of intra- and supra- deployment locations for a bio-prostetic aortic valve

M. A. Scarpolini1, G. Vagnoli1, F. Guglietta2, R. Verzicco2,1, F. Viola1

1Gran Sasso Science Institute (GSSI), Italy; 2Tor Vergata University of Rome, Rome, Italy

Aortic valve replacement is a surgical procedure to treat aortic valve diseases, such as stenosis and regurgitation. Bio-prosthetic valves, usually made from bovine or porcine pericardial tissue, mimic the natural flow dynamics of the native aortic valve and reduce the need for long-term anticoagulant therapy. However, the positioning of the stented frame relative to the native aortic annulus plays a critical role in determining the resulting blood flow patterns [1]. Specifically, the supra-annular configuration, characterized by positioning the valve ring superior to the native annulus while extending leaflets into the Valsalva sinuses, seeks to attenuate flow obstruction by circumventing interference with the native annulus. Conversely, the intra-annular approach, which closely mimics the physiological arrangement of the aortic valve, necessitates implantation of a smaller prosthesis with a corresponding reduction in valve effective orifice area, thereby potentially reducing hemodynamic performance [2]. This work focuses on the influence of deployment locations of bio-prosthetic aortic valves by examining blood flow characteristics in both intra-annular and supra-annular configurations. The problem is investigated numerically by solving fluid-structure interaction, incorporating the interplay between blood flow and the flexible valve leaflets within a realistic anatomy of the left heart. We select a small-sized heart, reproducing the scenario where patients with small aortic diameters suggest the surgeon to evaluate alternative surgical strategies. In addition, we consider a bioprosthetic valve model that resembles the LivaNova Crown PRT, specifically chosen because, unlike most prosthetic valves, it can be implanted in both configurations. This unique feature allows us to perform a controlled, high-fidelity numerical comparison within the same virtual patient, ensuring identical anatomical and functional conditions and isolating the effects of deployment strategy. The dynamic and transitional nature of hemodynamics is captured through direct solution of the incompressible Navier-Stokes equations using a staggered finite differences approach. Immersed boundary techniques are employed to address the large valve deformations. Structural mechanics is based on the Fedosov interaction potential method to model the behaviors of biological tissues [3-4]. The numerical model is used to compare hemolysis, wall shear stress, transvalvular pressure drop, and valve orifice area across the two prothesic deployment configurations.
This project has received funding from the European Research Council (ERC) under the European Union’s Horizon Europe research and innovation program (Grant No. 101039657, CARDIOTRIALS to F.V.). This work has received partial funding from the project MUR-FARE R2045J8XAW CUPE83C22005500001 (P.I. Luca Biferale).
[1] Vahidkhah & Azadani, Journal of biomechanics 58, 114-122 (2017).
[2] Kim et al., Interactive cardiovascular and thoracic surgery 28(1), 58-64 (2019).
[3] Viola et al., Scientific reports 13(1), 8230 (2023).
[4] Viola et al., Physical Review Fluids 8(10), 100502 (2023).



 
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