Simulation and Imaging for Mitral Regurgitation – SIMR

An innovative experimental tool for measuring chordae tension has been developed, along with new imaging strategies for measuring cardiac hemodynamics and estimating myocardial contractility in a clinical study. Advanced numerical tools were developed to simulate the mechanical interaction between blood, heart valves and myocardium.

Around fifteen research papers have been published in international journals, with different results on heart valve simulation, medical device development and estimation of cardiac contractibility from imaging data.

The results obtained offer promising perspectives, including the development of integrated in vitro and in silico approaches for heart valve hemodynamics, with the purpose of assessing new medical devices.

1. G. K. Rumindo, J. Ohayon, P. Croisille, and P. Clarysse, «In vivo
estimation of normal left ventricular stiffness and contractility
based on routine cine MR acquisition,« Medical Engineering &
Physics, vol. 85, pp. 16-26, 2020.
hal.archives-ouvertes.fr/hal-03093687
2. Daniel Grinberg, Rémi Buzzi, Matteo Pozzi, Rémi Schweizer,
Jean-Fabien Capsal, Bergamotte Thinot, Minh Quyen Le, Jean-
Francois Obadia, Pierre-Jean Cottinet, “Eco-audit of conventional
heart surgery procedures”, European Journal of Cardio-Thoracic
Surgery, 2021;, ezab320,
doi.org/10.1093/ejcts/ezab320

With 600 surgical operations per year, mitral insufficiency is the second cause of valvular surgery in France. Repair is preferred to replacement when it is possible. Cardiac ultrasound allows the quality of correction to be routinely assessed, but it does not measure the biomechanical impact of interventions on the mitral apparatus. A better understanding of this impact, based on objective physical quantities, would enable the optimization of the repair techniques.

The SIMR project aims at facing this major public health problem, with the following two objectives:

(1) Evaluate the physical consequences of mitral repair with new tools used in a clinical study involving 15 patients. Tissue remodeling and ventricular flow will be measured using advanced magnetic resonance imaging techniques, and chordae tension will be measured using an innovative device.

(2) Design numerical tools for the simulation of cardiac hemodynamics, blood/valve interaction and myocardial biomechanics, to provide the in silico counterpart of the in vivo measurements. In particular, a new fluid-structure coupling algorithm will be developed to allow a complete numerical simulation of the mitral apparatus, and inverse problem techniques applied to a finite element model will be used to estimate cardiac contractility.

The SIMR consortium gathers four complementary components: modeling and simulation (REO, M3DISIM, TIMC), clinical research (HCL), engineering (LGEF) and medical imaging (CREATIS). Active collaborations already exist between certain groups. The project will provide a unique opportunity to build new bridges between imaging, modeling, simulation and clinical research.

Several results with high scientific impact are expected. The device for measuring tensions in neo-cordages is a world first. At the end of the project, the impact of these tensions on the results of the repair and ventricular remodeling will be much better understood. The combination of magnetic resonance imaging velocimetry and numerical simulation is likely to be of great interest as intracavitary flows are currently a very active research field within in the imaging and simulation communities. Finally, a complete fluid-structure simulation of the mitral apparatus on a beating heart would be a major breakthrough in the field of cardiovascular simulation.