CN117057182A - Aortic valve stent contact finite element simulation method based on numerical simulation - Google Patents

Abstract

The invention discloses an aortic valve stent contact finite element simulation method based on numerical simulation, which comprises the following steps: firstly, constructing an original three-dimensional model based on cardiovascular image data and cardiovascular radiography images, and constructing an original artificial aortic valve stent three-dimensional model; step two, importing the three-dimensional model into finite element simulation software, and respectively setting biomechanical parameters and corresponding analysis models; step three, setting boundary conditions of an analysis model, and carrying out grid division on the three-dimensional model to determine grid data; step four, finite element simulation calculation is carried out according to biomechanical parameters, boundary conditions, grid data and an analysis model; fifthly, determining a coronary obstruction risk index and a postoperative paravalvular air leakage risk index according to the simulation result. The invention not only improves the accuracy of operation risk assessment, but also provides reference data for the design of the artificial valve stent and an effective reference for further optimizing the design and development of the artificial valve.

Description

A finite element simulation method for aortic valve stent contact based on numerical simulation

Technical field

The invention belongs to the field of biomechanical simulation technology, and specifically relates to a finite element simulation method of aortic valve stent contact based on numerical simulation.

Background technique

The aorta is the main blood vessel in the systemic circulation. The aortic valve is located between the left ventricle and the aorta. It is a membrane that prevents the blood flow from the aorta from returning to the left ventricle, and is responsible for pressure and loss. The aortic valve is a membrane located between the left ventricle and the aorta that prevents blood flow from the aorta from flowing back into the left ventricle. Because of its central location, the aortic valve has a close relationship with the various heart chambers and valves. It goes through an opening and closing process with every cardiac cycle. Frequent pressure causes the aortic valve to become a disease-prone part of the human body. Aortic valve disease will seriously threaten human life safety. Severe aortic valve disease will cause the heart's front and rear load to increase, which will then develop into left heart failure and even lead to sudden death of the patient. The main disease types of the aortic valve are physical lesions such as calcification and deformation. Calcification hinders the full range of movement of the leaflets, resulting in obstruction of blood flow from the left ventricle to the aorta and ventricular dysfunction. Due to the lack of effective targeted therapeutic drugs, transcatheter aortic valve replacement (TAVR) has become the main method of treatment. Compared with traditional thoracotomy, an interventional method is used to implant a stent to replace the diseased valve. This operation involves the artificial valve passing through The aorta is transported to a position close to the left ventricle, and is released at the aortic valve. The artificial valve replaces the native valve to work, without the need for thoracotomy and minimal damage to the body.

The current main method of preoperative planning is to judge and evaluate the model selection and implantation position of the artificial valve through the measurement results of preoperative and intraoperative imaging. Collect CT images of the aortic root, complete the determination and measurement of the aortic annulus, measure the left ventricular outflow tract, aortic sinus, and sinotubular junction, and measure the ascending aorta inner diameter, circumference, and coronary artery opening distance from the annulus. height, atherosclerosis, calcification distribution, etc., through MDCT imaging, we can clearly understand the shape of the aortic valve leaflets, the shape and degree of calcification at the junction of the leaflets and annulus, and can be used as a supplement to ultrasound imaging. Through image acquisition, clinicians can complete surgical risk assessment through image data. This assessment method is highly dependent on the experience of clinicians, lacks numerical basis for quantitative judgment, and results in poor accuracy.

Contents of the invention

In order to solve the above problems existing in the prior art, the present invention provides a finite element simulation method of aortic valve stent contact based on numerical simulation. The technical problems to be solved by the present invention are achieved through the following technical solutions:

A finite element simulation method of aortic valve stent contact based on numerical simulation, including the following steps:

Step 1: Based on the cardiovascular imaging data and cardiovascular angiography images, the original three-dimensional model of the patient's heart is reconstructed through computer three-dimensional modeling, and the original three-dimensional model of the artificial aortic valve stent is constructed; wherein the original three-dimensional model includes: indicating the main Original cardiac 3D model and calcified plaque 3D model of the arterial root, aortic valve and left ventricular outflow tract;

Step 2: Import the original three-dimensional heart model, the three-dimensional model of the calcified plaque, and the original three-dimensional model of the artificial aortic valve stent into the finite element simulation software, and set the original three-dimensional model of the heart and the three-dimensional model of the calcified plaque respectively. The biomechanical parameters of the three-dimensional model and the three-dimensional model of the original artificial aortic valve stent and the corresponding analysis model;

Step 3: Set the boundary conditions of the analysis model, mesh the original heart three-dimensional model, the calcified plaque three-dimensional model and the original artificial aortic valve stent three-dimensional model, and determine the mesh data;

Step 4: Perform finite element simulation calculations based on the biomechanical parameters, the boundary conditions, the grid data and the analysis model to obtain a three-dimensional stress cloud diagram of the heart and a three-dimensional stress cloud diagram of the scaffold;

Step 5: Determine the coronary artery obstruction risk index and postoperative paravalvular leakage risk index based on the three-dimensional stress cloud map of the heart and the three-dimensional stress cloud map of the stent and corresponding data.

In one embodiment of the invention, the method further includes:

The cardiovascular imaging data of the patient before surgery are obtained through computed tomography, and the cardiovascular imaging data after the contrast agent is injected into the patient are obtained through a contrast imaging system and an electrocardiogram gating system.

In one embodiment of the invention, the biomechanical parameter includes one or more of Young's modulus, Poisson's ratio and density.

In one embodiment of the present invention, the analytical model of the original three-dimensional heart model is a hyperelastic model; the analytical model of the three-dimensional calcified plaque model is a linear elastic model;

The expression of the hyperelastic model is:

In one embodiment of the present invention, the three-dimensional model of calcified plaque is a linear elastic model.

In one embodiment of the present invention, the boundary conditions include a fixed constraint on the segmentation position of the aortic root of the original three-dimensional heart model and a designation of the z direction and radial outward direction of the original three-dimensional artificial aortic valve stent model. Displacement.

In one embodiment of the present invention, the specified displacement in the z direction is 0;

The specified displacement along the radial direction is:

Among them, a represents the expansion distance of the original artificial aortic valve stent three-dimensional model, X represents the specified displacement added to the x direction, and Y represents the specified displacement added to the y direction.

Beneficial effects of the present invention:

The present invention simulates the pressure distribution of the aorta during the operation through finite element simulation, so as to effectively and accurately obtain patient-specific physiological state simulation information, thereby determining possible problems caused by the implantation of the physical model of each artificial valve stent. The postoperative risk index not only improves the accuracy of surgical risk assessment, but also provides reference data for the design of artificial valve stents, and provides an effective reference for further optimizing the design and development of artificial valves.

The present invention will be further described in detail below with reference to the accompanying drawings and examples.

Description of the drawings

Figure 1 is a schematic flow chart of a finite element simulation method of aortic valve stent contact based on numerical simulation provided by an embodiment of the present invention;

Figure 2 is a schematic diagram of the meshing of the original three-dimensional heart model, the three-dimensional model of calcified plaque and the three-dimensional model of the original artificial aortic valve stent provided by the embodiment of the present invention;

Figure 3 is a three-dimensional stress cloud diagram of the heart and a three-dimensional stress cloud diagram of the stent provided by the embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to specific examples, but the implementation of the present invention is not limited thereto.

Embodiment 1

As shown in Figure 1, a finite element simulation method of aortic valve stent contact based on numerical simulation includes the following steps:

Step 1: Based on the cardiovascular imaging data and cardiovascular angiography images, the original three-dimensional model of the patient's heart is reconstructed through computer three-dimensional modeling, and the original three-dimensional model of the artificial aortic valve stent is constructed.

Among them, the original three-dimensional model includes: the original three-dimensional heart model indicating the aortic root, aortic valve and left ventricular outflow tract and the three-dimensional model of calcified plaque.

Before step one, obtain the cardiovascular image data of the patient before TAVR through computed tomography, and extract and segment the image data of the aortic root, aortic valve, left ventricular outflow tract, and calcified plaque parts. The cardiovascular imaging data are cardiovascular images without contrast agent injection. After the patient is injected with contrast agent, he or she is scanned by the contrast equipment, and ECG gating can be used to assist in scanning to obtain cardiovascular contrast images.

Here, the three-dimensional model of the original prosthetic aortic valve stent can be constructed based on the relevant data of the model of the stent to be used.

Step 2: Import the original 3D heart model, the calcified plaque 3D model and the original artificial aortic valve stent 3D model into the finite element simulation software, and set the original heart 3D model, the calcified plaque 3D model and the original artificial aortic valve stent 3D model respectively. Biomechanical parameters of the model and corresponding analytical models. The biomechanical parameters include one or more of Young's modulus, Poisson's ratio, and density.

Specifically, the original three-dimensional heart model and the three-dimensional model of the calcified plaque were imported into the finite element simulation software, and the biomechanical parameters of the original three-dimensional heart model and the calcified plaque and other related parameters were set, and the initial position was set. Then import the original artificial aortic valve stent 3D model into the finite element simulation software, set the position of the original artificial aortic valve stent 3D model to the initial implantation position on the original heart 3D model, and set the original artificial aortic valve stent Biomechanical parameters and other relevant parameters of the three-dimensional model. At the same time, the analysis model of the original three-dimensional heart model is set as a hyperelastic model, the analysis model of the three-dimensional calcified plaque model is a linear elastic model, and the original three-dimensional artificial aortic valve stent model is a mathematical model describing a regular shape (such as a circular tube shape) .

Considering that the mechanical properties of cardiac tissue are much more complex than classical mechanics. Hooke's law, which is usually used to describe the mechanical behavior of stretching, shearing, and torsion, is no longer sufficient to satisfy the mechanical behavior of cardiac tissue. Mechanical properties of cardiac tissue: viscoelasticity, superelasticity, anisotropy, nonlinearity, and incompressibility. Therefore, the physical model of the aorta needs to be described by a hyperelastic model. The two-parameter Mooney-Rivlin constitutive model is used to describe the physical properties of the aortic root, aortic valve, and left ventricular outflow tract:

After expanding the above formula, we get:

Among them, W represents elastic strain energy, C ₁₀ , C ₀₁ , and d represent parameters. Parameters C ₁₀ =0.83778, C ₀₁ =-0.42406, I ₁ and I ₂ represent the first invariant and the second invariant of the strain tensor respectively. , J represents volume deformation.

In a feasible implementation method, the original three-dimensional model of the artificial aortic valve stent can be pre-constructed in step one, or can be constructed in the finite element simulation software when performing step two. After each model is imported into the finite element software, each model can be simplified by setting relevant parameters.

Step three: Set the boundary conditions of the analysis model, mesh the original three-dimensional model and the original three-dimensional model of the artificial aortic valve stent, and determine the mesh data.

In this step, boundary conditions include contact pairs, fixed constraints, source boundaries (outer surface of the stent), target boundaries (inner wall of the aortic valve), etc.

Setting boundary conditions also includes: setting the aortic root, aortic valve, and calcified plaque to form a union, adding fixed constraints to the segmentation position of the aortic root, and setting the specified displacement in the z direction to 0. Add a displacement condition perpendicular to the tangential surface on the inside:

Among them, a represents the expansion distance of the original artificial aortic valve stent three-dimensional model, X is the specified displacement added to the x direction, and Y is the specified displacement added to the y direction.

When dividing the mesh for each part, triangular mesh, sweep, free tetrahedral mesh, etc. are used to divide the mesh based on the specific geometric conditions of the model, as shown in Figure 2.

Step 4: Perform finite element simulation calculations based on biomechanical parameters, boundary conditions, grid data and analysis models to obtain a three-dimensional stress cloud map of the heart and a three-dimensional stress cloud map of the scaffold. In this step, finite element simulation is used to simulate the release process of the artificial aortic valve stent during the operation and the pressure distribution during the contact process with the aortic valve. The finite element simulation calculation is completed and the simulation results (original artificial aortic valve stent) are obtained. The three-dimensional stress cloud diagram of the heart corresponding to the three-dimensional heart model after the three-dimensional model of the arterial valve stent is released and expanded, and the three-dimensional model of the calcified plaque, as well as the three-dimensional stress cloud diagram of the stent after the three-dimensional model of the original artificial aortic valve stent is released and expanded, as shown in Figure 3).

Step 5: Determine the coronary artery obstruction risk index and postoperative paravalvular leakage risk index based on the three-dimensional stress cloud map of the heart and the three-dimensional stress cloud map of the stent and the corresponding data.

In this step, measurements are made on the three-dimensional stress cloud map of the heart and the three-dimensional stress cloud map of the stent to obtain relevant data. For example, the distance from the coronary artery opening to the artificial valve is measured, and the occurrence of coronary artery obstruction is evaluated based on the distance from the coronary artery opening to the artificial valve. The risk index, such as the distance from the coronary artery opening to the artificial valve, is compared with the distance threshold, and the comparison result corresponds to the risk index for coronary artery obstruction. Based on the measured expansion data of the three-dimensional model of the original prosthetic aortic valve stent, the risk index of postoperative paravalvular leakage was evaluated.

The aortic valve stent contact finite element simulation method based on numerical simulation provided by the present invention obtains the real patient's aortic root cardiovascular imaging data based on computed tomography in advance, and on this basis, reconstructs the patient through computer three-dimensional modeling. The three-dimensional model of the aortic root, aortic valve and other parts, using finite element simulation, can simulate the introduction and release process of different original artificial aortic valve stent 3D models, and can obtain the 3D corresponding to various original artificial aortic valve stents. The simulation results of the model can be used to determine the postoperative risk information that may be caused by the implantation of each original three-dimensional artificial aortic valve stent model, and provide data for clinical artificial valve design and clinical transcatheter aortic valve replacement surgery based on the finite element simulation. refer to.

In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more than two, unless otherwise explicitly and specifically limited.

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "an example," "specific examples," or "some examples" or the like means that specific features are described in connection with the embodiment or example. , structures, materials or features are included in at least one embodiment or example of the invention. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may join and combine the different embodiments or examples described in this specification.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be concluded that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of them should be regarded as belonging to the protection scope of the present invention.

Claims (7)

1. A finite element simulation method of aortic valve stent contact based on numerical simulation, which is characterized by including the following steps: Step 1: Based on the cardiovascular imaging data and cardiovascular angiography images, the original three-dimensional model of the patient's heart is reconstructed through computer three-dimensional modeling, and the original three-dimensional model of the artificial aortic valve stent is constructed; wherein the original three-dimensional model includes: indicating the main Original cardiac 3D model and calcified plaque 3D model of the arterial root, aortic valve and left ventricular outflow tract; Step 2: Import the original three-dimensional heart model, the three-dimensional model of the calcified plaque, and the original three-dimensional model of the artificial aortic valve stent into the finite element simulation software, and set the original three-dimensional model of the heart and the three-dimensional model of the calcified plaque respectively. The biomechanical parameters of the three-dimensional model and the three-dimensional model of the original artificial aortic valve stent and the corresponding analysis model; Step 3: Set the boundary conditions of the analysis model, mesh the original heart three-dimensional model, the calcified plaque three-dimensional model and the original artificial aortic valve stent three-dimensional model, and determine the mesh data; Step 4: Perform finite element simulation calculations based on the biomechanical parameters, the boundary conditions, the grid data and the analysis model to obtain a three-dimensional stress cloud diagram of the heart and a three-dimensional stress cloud diagram of the scaffold; Step 5: Determine the coronary artery obstruction risk index and postoperative paravalvular leakage risk index based on the three-dimensional stress cloud map of the heart and the three-dimensional stress cloud map of the stent and corresponding data. 2. A finite element simulation method of aortic valve stent contact based on numerical simulation according to claim 1, characterized in that the method further includes: The cardiovascular imaging data of the patient before surgery are obtained through computed tomography, and the cardiovascular imaging data after the contrast agent is injected into the patient are obtained through a contrast imaging system and an electrocardiogram gating system. 3. A finite element simulation method of aortic valve stent contact based on numerical simulation according to claim 1, characterized in that the biomechanical parameters include one or more of Young's modulus, Poisson's ratio and density. . 4. A finite element simulation method of aortic valve stent contact based on numerical simulation according to claim 3, characterized in that the analysis model of the original three-dimensional heart model is a hyperelastic model; the three-dimensional calcified plaque model The analytical model is a linear elastic model; The expression of the hyperelastic model is: 5. A finite element simulation method of aortic valve stent contact based on numerical simulation according to claim 4, characterized in that the three-dimensional model of calcified plaque is a linear elastic model. 6. A finite element simulation method of aortic valve stent contact based on numerical simulation according to claim 5, characterized in that the boundary conditions include fixed constraints of the segmentation position of the aortic root of the original three-dimensional heart model and the Describe the specified displacement in the z direction and radially outward of the three-dimensional model of the original prosthetic aortic valve stent. 7. A finite element simulation method of aortic valve stent contact based on numerical simulation according to claim 6, characterized in that the designated displacement in the z direction is 0; The specified displacement along the radial direction is: Among them, a represents the expansion distance of the original artificial aortic valve stent three-dimensional model, X represents the specified displacement added to the x direction, and Y represents the specified displacement added to the y direction.