IMD Deformation Simulation Using Segmented Mechanical Equilibrium
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Solution Overview
Problem
Current methods for simulating the final position and deformation of implantable medical devices (IMDs) in natural cavities are limited in precision, particularly for non-tubular shapes like braided cages, and are computationally intensive, making them unsuitable for clinical practice, especially in emergency situations.
Innovation Solution
A method involving the determination of an intermediate deformation state of the IMD, followed by calculation of a mechanical equilibrium state, which simplifies the simulation by using a three-dimensional wall model and accounting for mechanical behaviors of both the IMD and the cavity wall, allowing for rapid and robust prediction of the IMD's final position and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical modelling of segments is adopted to predict the final length of IMD, then the prediction precision for flow diverter type implants is improved, but the method is not suitable for implants of general non-cylindrical shape and cannot calculate a field of deformations
Solution Approach 1:
The IMD is discretized into a set of longitudinal three-dimensional segments, where each segment can be independently modeled and analyzed. This segmentation allows the method to handle various implant shapes by applying appropriate mechanical models to each segment, thus resolving the contradiction between prediction precision for specific shapes and adaptability to different shapes.
Solution Approach 2:
The method changes the mechanical parameters and modeling approach based on the implant type. For flow diverter implants, a cylindrical segment model is used, while for other shapes, the mechanical behavior parameters are adjusted to reflect the specific geometry and material properties, enabling versatile application across different implant types.
2Productivity
If a simulation method based on cylindrical shape assumption is used, then the calculation speed is improved, but the precision for non-cylindrical implants like intrasaccular cages is reduced
Solution Approach 1:
The method introduces a dynamic mechanical equilibrium calculation that iteratively adjusts the deformation state of each segment based on mechanical stresses and strains. This dynamic approach allows the simulation to adapt to non-cylindrical shapes while maintaining reasonable calculation speed, resolving the contradiction between calculation efficiency and precision for complex geometries.
Solution Approach 2:
The method performs a preliminary geometric stress calculation based on the cylindrical assumption to obtain an initial deformation state, then refines this solution through mechanical equilibrium iteration. This two-stage approach maintains calculation speed by using the simplified model first, then improves precision through the refined mechanical model for non-cylindrical shapes.
3Ease of operation
If planar local measurements are used for IMD selection, then the ease of operation is improved, but the reliability of prediction of final position and shape is reduced
Solution Approach 1:
The method creates a three-dimensional numerical copy or model of the patient's artery based on medical imaging data. This 3D model allows for accurate simulation of IMD deployment and prediction of final position and shape, replacing the unreliable planar measurements while maintaining ease of operation through automated computer-assisted analysis.
Solution Approach 2:
The method replaces the manual planar measurement system with an automated computer-based mechanical simulation system. The simulation calculates mechanical stresses, strains, and deformations to predict the final IMD configuration, providing reliable predictions while keeping the user interface simple and easy to operate.
4Measurement precision
If a complete mechanical equilibrium calculation is performed for IMD deformation, then the precision of deformation field calculation is improved, but the calculation time increases making it unsuitable for clinical practice
Solution Approach 1:
The complete mechanical equilibrium calculation is divided into separate segment-level calculations. Each of the discretized longitudinal segments is analyzed independently for mechanical equilibrium, which reduces the overall computational complexity and time while maintaining precision in the deformation field calculation through the cumulative effect of all segments.
Solution Approach 2:
The method performs mechanical equilibrium calculation for each segment rather than attempting to model the entire implant as a single unit. This partial action approach provides sufficient precision for clinical decision-making without the excessive computational burden of a complete global equilibrium calculation, achieving the right balance between precision and speed.
Data Source
AI summary
The invention relates to a method for simulating the deformation of an IMD after implantation in a natural cavity, from a three-dimensional model of a wall of the cavity, comprising the steps of:determination of an intermediate deformation state of a numerical IMD, deformed as a function of a shape of the wall model while remaining included in said shape,calculation of a mechanical equilibrium state of the numerical IMD from the intermediate deformation state, comprising the calculation of mechanical stresses undergone by the numerical IMD in the intermediate deformation state which are a function of the mechanical behaviours of the numerical IMD and the wall model, and relaxation of said stresses,the behaviour of the wall model being taken as non-deformable rigid during the calculation of the mechanical equilibrium state,the mechanical behaviour of the numerical IMD, and/or the rest state of the numerical IMD, being different between the determination of the intermediate deformation state and the calculation of the mechanical equilibrium.