Aim: To perform a quantitative analysis of the effectiveness of three concepts of heart valve prosthesis support frames from the perspective of their safety under the most critical loads, conducted through numerical modeling.Materials and Methods. The study utilized three computer-generated concepts of stent-like support frames, created based on the analysis of similar balloon-expandable prostheses. The modeling was conducted using Abaqus/CAE software and included the analysis of two key loads characteristic for this element: compression and implantation phases. A linear description of cobalt-chromium was used as the material model. The feasibility of the concepts was quantitatively assessed using von Mises stress and its qualitative distribution on the surface of the models as stress contours.Results. The analysis revealed that two of the three proposed models experienced stresses exceeding the strength limit (933 MPa) – 999.6 and 954.0 MPa during the compression phase and reaching 1022.4 and 1044.7 MPa, respectively, during the implantation phase. Concept 3 had significantly lower stresses during loading; however, in the working state, the indicators approached the threshold, reaching 924.2 MPa.Conclusion. Numerical modeling identified the inefficacy of concepts 1 and 2 and directions for optimizing concept 3 – reducing amplitudes to form a “strength reserve” for stress. The analysis emphasized the importance of numerical modeling in the early assessment and optimization of medical devices.

The physical and mechanical characteristics of the component materials of bioprosthetic heart valves presented in clinical practice in Russia were obtained and generalized for subsequent adaptation of the properties for numerical modeling problems. It was shown that all materials studied have pronounced nonlinearity and can be represented only in the form of polynomial models. A comparison of the results of computer modeling based on the obtained material coefficients did not demonstrate any differences with the data of full-scale bench tests, which made it possible to verify the computer models.

Background. Using numerical modeling to study biomechanics of implantable devices for cardiovascular healthcare can help specialists understand underlying mechanisms of clinical complications caused by these devices.Aim: To describe the results of numerical modeling of aneurysm formation in vascular grafts based on the simulation of degradation of their mechanical properties.Material and Methods. The simulation was carried out using a three-dimensional computer model obtained by high-resolution computed tomography of the vascular graft “KemAngioProtez” (CJSC “NeoKor”, Russia). Using the 3D model obtained with a specialized script in the Abaqus/CAE environment (Dassault systems, USA), we have simulated the decrease in the elastic modulus (from 100 to 10%) with post-threshold stresses in the material and the accumulation of plastic strain.Results. Undergoing 150 loading cycles, the vascular wall in the model swelled up to 0.7 mm in the radial direction, and its mechanical properties degraded significantly (by 90% compared to baseline) due to prolonged pressure exposure. The value of maximum plastic deformation was 0.55%.Conclusion. Numerical modeling of graft mechanical properties degradation can assist in qualitative and quantitative assessment of the areas of aneurysm formation. The method makes it possible to visualize the swelling areas and can be used as a valuable tool to complement the existing approaches to studying vascular grafts, and biografts in particular.

Background. The average lifespan of a bioprosthetic heart valves (BHVs) is limited to 10–15 years due to structural valve degeneration (SVD). One of the causes of SVD is the infiltration of immune cells. Inflammation like this usually develops several years after valve replacement, the cause of it remains unknown. Presumably, the main stimulus of the immune response is an asymptomatic colonization by bacterial agents.Aim: To study bacterial invasion of BHVs explanted due to SVD, and to identify patterns in microorganism and cellular infiltrate localization.Material and Methods. 23 BHVs excised during replacement due to SVD were included in the study. The identification of bacteria in the samples was carried out by Gram staining and PCR analysis. Immunohistochemical staining with antibodies to markers CD45 (pan-leukocyte marker), CD68 (macrophage marker), CD3 (T-lymphocyte marker) and neutrophil elastase (ELA2) were used for phenotyping of immune cells. The composition of BHVs tissues was studied using Russell-Movat pentachrome staining.Results. All BHVs showed traditional signs of SVD (perforations and large calcifications at the base and dome of the leaflets, ruptures in the commissural zone), but had no signs of prosthetic valve endocarditis (no vegetation, blood culture and swab results were negative). Using the histological method, we detected bacterial cells in 19 of the 23 studied valves (82.6%), whereas PCR data indicated the presence of bacteria in 11 (47,8%) valves (Streptococcus ssp. and Staphylococcus ssp. without species identification). Moreover, we identified the co-localization of colonies of microorganisms and inflammatory infiltrates composed of macrophages (CD45+, CD68+) and neutrophils (CD45+, ELA2+).Conclusion. Bacteria commonly cause asymptomatic colonization of BHVs which is strongly associated with inflammatory cell infiltration.

The aim of the study was to compare scenarios of numerical modeling of the operation of a heart valve bioprosthesis, identifying their advantages and limitations. Material and methods. Numerical modeling was conducted in the Abaqus/ CAE (Dassault Systèmes, France) engineering analysis environment, simulating two cycles of the valve apparatus’s operation. In total, three different computer models were studied, each providing different levels of detail and complexity of the “UniLine” bioprosthesis. Model No.1 was the most simplified and considered only the geometry of the flap; Model No. 2 incorporated elastic connectors with variable stiffness; Model No. 3 included a composite support frame. Qualitative validation of the modeling results was conducted by comparing with the bench tests data obtained on the hydrodynamic stand (ViVitro Labs, Canada) during tests of the corresponding clinical model of the “UniLine” bioprosthesis. Results. One of the setups, Model No. 2, displayed an artificial stress concentration according to Von Mises in the connector attachment area, reaching 2.695 MPa, which is close to the material’s strength limit. Other setups showed a more moderate stress distribution – up to 0.803 and 0.529 MPa. Moreover, it was demonstrated that only Model No. 2 and Model No. 3 reproduce the key effect of the bioprosthesis operation, the mobility of the commissural posts, ensuring a qualitative match with the work in bench conditions. Conclusions. A methodology is proposed that may be useful for conducting further in silico studies of heart valve bioprostheses. Boundary conditions, methods for linking prosthetic components, and opportunities for large-scale “exploratory” studies based on using simplified models are described. The study results confirm the necessity of including all prosthesis components in the numerical model for a more comprehensive and realistic representation of its biomechanics. Such detail contributes to a more accurate safety and effectiveness assessment of the device and can also serve as a foundation for its further optimization.

HighlightsMicro-computed tomography allows specialists to qualitatively and quantitatively assess the structure of calcified areas of explanted bioprosthetic heart valves.This method enables the evaluation of changes in the structure of the bioprosthesis that have occurred during its prolonged operation. Aim of the study. To evaluate the potential of high-resolution tomography for the study of mitral valve bioprostheses of different designs explanted due to dysfunction and various calcification patterns (microcalcification and macrocalcification).Methods. Single samples of the «UniLine» and «PeriCor» bioprostheses were the objects of study, they were explanted due to dysfunction developed after 76 and 87 months of operation in recipients. The peculiarities of calcification localization in the structure of bioprostheses were studied using high-resolution tomography followed by reconstruction of volumetric images and quantitative analysis of radiodense areas. Moreover, we used light microscopy with Alizarin Red S staining to detect calcifications.Results. The study results showed that the nature of the distribution and volume of calcinates significantly differ between the studied samples: for the «UniLine» bioprosthesis, the affected areas were located in the leaflet material and constituted 21.1% of the total biological tissue volume; for the «PeriCor» bioprosthesis, calcifications were diffusely distributed in small structural formations, accounting for a total of 5.1% of the biological material, primary localized on the «auxiliary» structures of the prosthesis – the covering made of porcine or calf xenopericardium. In addition, high-resolution tomography allowed us to determine the degree of deformation of the «UniLine» bioprosthesis frame, with the posts deviating inward by 1.1–1.4 mm.Conclusion. The possibility of using computed microtomography for qualitative and quantitative assessment of calcified xeno-pericardial and xeno-aortal bioprostheses has been demonstrated. However, this method is limited in its ability to detect macrocalcification within the leaflet thickness.

Highlights:Epoxy-treated xenopericardium modified with polyvinyl alcohol has increased resistance to calcification and proteolytic degradation in vitro.Cyclic loads negatively affect fatigue life of studied material, moreover, this process is accompanied by deterioration of its anti-calcium and anti-enzyme properties. Additional studies aimed at improving the wear resistance of the hydrogel in the biological material are required. Aim. To study the resistance of epoxy-treated bovine pericardium modified with polyvinyl alcohol to calcification and proteolytic degradation in collagenase after exposure to cyclic loading.Material and methods. The epoxy-treated patches made with xenopericardium were treated with polyvinyl alcohol according to the original method, after that they were subjected to cyclic loading (70 million cycles) using the HiCycle wear tester system. Visualization of the surface and internal structure of the biomaterial was performed by scanning electron microscopy. The resistance to calcification was assessed by incubating the samples in a solution saturated with calcium ions and phosphate ions for 3 and 6 weeks, followed by quantitative measurement of the calcium by spectrophotometry. The susceptibility of the samples to proteolytic degradation was determined by weight loss after incubation in a solution of clostridial collagenase for 24 hours. The control group consisted of patches of unmodified epoxy-treated bovine pericardium.Results. After cyclic loading, patches of xenopericardium modified with polyvinyl alcohol showed signs of fatigue (cracks on the surface and large cavities in the internal structure). Although cyclic loading significantly worsened the resistance of the modified tissue to calcification and proteolytic degradation (by 3 and 5 times, respectively, relative to the values obtained for patches stored under static conditions), patches from this group showed better results compared to unmodified patches. Thus, they contained 1.5 to 2 times less calcium after 3 and 6 weeks of incubation in a calcium-saturated solution. Mass loss after incubation in collagenase was 1.5 times lower for patches of modified biomaterial undergoing cyclic loading compared to unmodified patches.Conclusion. The proposed modification method of the epoxy-treated xenopericardium with polyvinyl alcohol increases the resistance of biological tissue to calcification and proteolytic degradation. Although cyclic loading negatively affects the protective properties of the polymer coating over time, this type of modification can potentially slow down the degeneration of biomaterial used in manufacturing of bioprosthetic heart valves.

According to various estimates, more than 9,000 artificial heart valve implants were performed in specialized medical centers in Russian Federation in 2020 19.1 % of these implants were based on animal tissues. Such devices have high biocompatibility, but after 10–15 years from one third to one half require reoperation due to the development of various dysfunctions. Despite the advantages of biological prosthetic heart valves and the prevalence of their use in the clinic, there is a need for their optimization and refinement to improve postoperative hemodynamics and increase life spin. In this work, we applied an improved method to create the geometry of a leaflets and its evaluation to the commercial prosthesis «UniLine» (Kemerovo, CJSC «NeoKor») 23 standard sizes. An approach is demonstrated that includes a screening study of a large number of geometries (N = 6766) and detailed modeling (N = 4) of selected designs as part of the final product, taking into account interaction with the composite frame. The results obtained demonstrate the ability of the proposed method to optimize existing commercial models of prosthetic heart valves. An expanded set of construction parameters allowed us to select a design with peak maximum principal stresses of 1.89 and 0.68 MPa, as well as providing an open area of 233.08 and 267.34 mm2 with a maximum possible 314 mm2 for detailed and screening studies, respectively. At the same time, the area of the lumen in the diastolic phase in the prosthesis does not exceed 0.4 mm2 for the models shown. The presented results show the possibility of the method to create and evaluate "optimal" designs of flap devices according to a number of critical metrics for ensuring better hemo- and biomechanics – stresses occurring during the cardiac cycle, the presence of a twisting effect in the diastolic phase, as well as the ability to ensure maximum orifice area and locking quality.

Objective: to conduct a pilot study of the effect of bioprosthetic heart valve leaflet calcification on biomechanics and to identify the «stress in the material – dysfunction» relationship. Materials and methods. The study’s focus was on two commercially available UniLine bioprosthetic mitral valves sized 26 and 30 (NeoCor, Russia). The samples were subjected to microcomputer tomographic scanning in order to reconstruct calcium volumes. The resulting 3D models were correlated with prostheses of corresponding sizes and projected to the volume of the locking element in the Abaqus/CAE engineering analysis software (Dassault Systemes, France).Results. According to numerical modeling, the maximum principal stresses increased significantly to 90.8 MPa in the samples, the opening decreased qualitatively, and impact on the prosthetic frame increased. Comparison of stress diagrams of numerical simulation with samples demonstrates the relationship between peak amplitude and rupture and thinning localizations in the flap apparatus.Conclusion. The work presented demonstrated the findings of a pilot study of the connection between biomechanics in a patient-specific calcified mitral prosthetic heart valve UniLine and macroscopic characterization of explanted samples. The comparative stage showed that stress values correlate with localization of leaflet dysfunction.

HighlightsThe incorporation of multi-walled carbon nanotubes into the structure of the poly(styrene-block-isobutylene-block-styrene) polymer matrix leads to an increase in the tensile strength and Young's modulus of the nanocomposites. The resulting nanocomposites retain high biocompatibility and can be used as elements of implanted cardiovascular products. AbstractAim. To synthesize and modify poly(styrene-block-isobutylene-block-styrene) (SIBS) with two types of multi-walled carbon nanotubes (MWCNTs) in different concentrations to improve its mechanical properties.Methods. SIBS was synthesized by controlled cationic polymerization. Polymer nanocomposites were prepared using ultrasonic dispersion followed by casting films from a polymer solution. The resulting nanocomposite films were subjected to mechanical tests under uniaxial tensile conditions. Tensile strength, elastic-strain properties, and plastic deformation under cyclic loading were assessed. The structure of the nanocomposites was analyzed by scanning electron microscopy. The hydrophilicity of the surface of the materials was studied by measuring the contact angle with water. The cytotoxicity of the resulting polymer films was assessed by the viability and metabolic activity of endothelial cells cultured on the surface of the nanocomposites.Results. Polymer nanocomposites with a uniform distribution of MWCNTs in the polymer matrix were obtained. SIBS films modified with 1% MWCNTs with a diameter of 50–90 nm showed an increase in tensile strength by 16.4% compared to SIBS polymer. Increasing the concentration of MWCNTs to 8% led to a decrease in the strength of polymer materials by 19,6%. The inclusion of nanoparticles into the polymer matrix significantly increased the Young's modulus of the studied polymers with a MWCNT content above 4%. With an increase in the content of MWCNTs in the nanocomposites, an increase in hydrophilicity was also observed, while the cytotoxicity of the samples towards endothelial cells was not noted.Conclusion. Nanocomposites based on SIBS and MWCNTs, due to their high strength and biocompatibility, can become a promising material for the development of various medical products, in particular prosthetic heart valves.

HighlightsThe presented numerical model of the bioprosthesis support frame for sutureless fixation needs to be optimized to reduce the amplitude of the von Mises stresses.The presented setup of numerical modeling has been validated using the study of commercial analogs. AbstractAim. To assess the stress-strain state of three computer models of TAVI prosthesis support frames during crimping and shaping to the delivery configuration.Methods. The study included three models of stent-like support frames for balloon-expandable devices, which are intended to serve as a foundation for the subsequent development of a domestic aortic valve prosthesis: two models of commercial bioprostheses and one experimental. The objects were evaluated numerically under the conditions of stress-strain state that arises in the stent support frames, simulating two loads: crimping and shaping to the delivery configuration. The study was conducted using the numerical modeling complex Abaqus/CAE (“Dassault Systemes”, France). The key indicators for evaluation were the von Mises stress, as a strength criterion, and its distribution over the frame; the presence and proportion of elastic recoil.Results. It was shown that all samples are capable of reaching the required diameter without excessive material. A quantitative investigation of the Von Mises stress showed that commercial models display amplitudes below the material`s strength limit (892.4 and 916.8 MPa), whereas the proprietary model exceeds this limit, reaching 991.4 MPa, requiring geometry optimization. Shaping to the delivery configuration indicates that all models provide safe expansion up to 26 mm, with a Von Mises stress level in the range of 882.4–914.1 MPa, which is below the strength limit of the cobalt-chrome alloy. Moreover, we have noted heterogeneous stress distribution, with concentration in the lamella junction areas.Conclusion. Thus, it has been demonstrated that numerical modeling and the finite element method can be effectively applied to assess the stress-strain state of sutureless prostheses. Geometry optimization and further development of this project – the development of a Russian minimally invasive aortic valve prosthetic system, may contribute towards increasing the accessibility of this treatment method.

Highlights. Using ECHO and MSCT data, a numerical assessment of hemodynamic effects of paraprosthetic regurgitation following transcatheter aortic valve replacement was performed. A significant increase in the fluid flow, wall and viscous shear stresses in the area of regurgitation is shown. The modeling technique described in the paper can be used prospectively in assessing the optimal treatment modality in terms of predicting the quantitative characteristics of the flow, associated with the risks of destruction of red blood cells and thrombosisAim. To make a numerical assessment of hemodynamic effects of paraprosthetic regurgitation following transcatheter aortic valve replacement based on retrospective clinical data.Methods. The study included echocardiography and multi-slice computed tomography data as input data for modeling one pulsation of a fluid similar in properties to blood. Reconstruction of the paraprosthetic fistula and the ascending aorta was performed in the Mimics medium (Materialise, Belgium). The obtained 3D models were processed in the Salome software (OPEN CASCADE SAS, France), after which they were exported to HELYX-OS (ENGYS, Great Britain) to build a finite element mesh. The flows were modeled using the OpenFOAM software package version 6 (The OpenFOAM Foundation Ltd, UK).Results. The simulation result, expressed quantitatively and qualitatively in the form of diagrams of the measured parameters – fluid flow velocities, wall and viscous shear stresses, shows a significant increase in indicators in the area of paraprosthetic regurgitation. Thus, the velocity in the affected area was 1.9–4.2 m/s, which is 3.8 higher than the average value in the entire computational area. The wall shear stress value was up to 61 Pa in the critical area, which may indicate an increased risk of thrombus formation due to the initiation of the clotting cascade through the von Willebrand factor. The value of viscous shear stress, the main component of the destruction of red blood cells in laminar flow, amounted to 20–26 Pa, which, in general, is not enough for mechanical hemolysis.Conclusion. The modeling technique described in the paper can be used prospectively in assessing the optimal treatment modality in terms of predicting the quantitative characteristics of the flow, associated with the risks of destruction of red blood cells and thrombosis.

Five commercial patches and one unchanged native bovine xenopericardium are studied on a test setup to supplement the existing data on the physical and mechanical properties of commercial patches used for reconstructive interventions on the heart and blood vessels and to adapt the corresponding models for applications in computer simulation environment. The models are verified under conditions for numerical simulation of the uniaxial tension experiment using the finite element method. The full-scale study of physical and mechanical properties shows that all materials exhibit developed nonlinearity, which is manifested as an initial low-slope fragment of stress with a subsequent increase in rigidity. The results of numerical verification of the coefficients for models of hyperelastic materials show high convergence with the results of field tests. The results of evaluation of the physical and mechanical properties of patches for reconstructive surgery of the heart and blood vessels used in the Russian Federation are presented. The resulting coefficients of the models for these materials can be used in the environment of engineering analysis for the problems of numerical simulation using the finite element method.

HighlightsAdhesion formation is a classic complication of any surgical intervention, which reduces the quality of life of patients and carries the risk of fatal complications during repeated surgery. Moreover, there is an issue of postoperative wound infection. Currently, there are no effective anti-adhesive agents with antibacterial activity in the arsenal of surgeons. Aim. To justify and develop biodegradable anti-adhesive membranes with antibacterial activity.Methods. The membranes were made by electrospinning using a composition of biodegradable polymers: polylactide-co-glycolide copolymer (50:50) Mm 20–30 KDa and ε-caprolactonone. The antibiotic Tigacil was added to the polymer solution to impart antibacterial properties to the membrane. The surface structure of the membranes was evaluated using a scanning electron microscope. Physical, mechanical and hemocompatibility properties were studied. The antibacterial activity of the membranes was evaluated after manufacturing, sterilization and storage for 24 months.Results. The inclusion of Tigacil in the membrane composition contributed to a decrease in fiber thickness by almost 4 times, while the packing of fibers became denser, which affected the increase in the strength of the modified membranes. Samples of membranes before and after the inclusion of Tigacil have no negative effect on erythrocytes The obtained results confirm the antibacterial activity of membranes against Staphylococcus aureus and Klebsiella pneumoniae, as well as the preservation of these properties after sterilization and during 2 years of storage.Conclusion. The inclusion of Tigacil in the polymer composition makes it possible to create biodegradable anti-adhesive membranes with antibacterial activity, which is maintained for two years after the manufacture. The inclusion of Tigacil in the polymer fiber composition does not adversely affect the initial properties of the membrane.

The physical-mechanical characteristics of materials-components of bioprostheses of heart valves presented in clinical practice in Russia, with subsequent adaptation of properties for numerical modeling tasks, have been obtained and generalized. It is shown that all the studied materials have a pronounced nonlinearity and can be represented only in the form of polynomial models. Comparison of the results of computer modeling based on the obtained coefficients of materials showed no differences with the data of full-scale bench tests, which made possible to verify computer models.

Highlights Stabilization of bovine pericardial tissue by ethylene glycol diglycidyl ether does not remove the N-glycolylneuraminic acid contained in its structure, which is one of the most immunoreactive glycan xenoantigens; N-glycolylneuraminic acid can potentially cause early immune rejection of epoxy-treated bioprosthetic heart valves. Aim. To assess the presence of N-glycolylneuraminic acid (Neu5Gc) in an intact bovine pericardial tissue stabilized by ethylene glycol diglycidyl ether and in the leaflets of epoxy-treated bioprosthetic heart valves (BHV) explanted due to dysfunction. Methods . By means of immunochemistry (using anti-Neu5Gc antibodies), we studied the fragments of 5 samples of intact epoxy-treated bovine pericardium commonly used in cardiac surgery. Similarly, we examined the fragments of the leaflets of 8 epoxy-treated BHVs that lasted for different time periods (1 day to 68 months) and excised during reoperation. The native bovine pericardium and the leaflets of 3 human aortic valves (AV) removed during reoperation in patients with aortic stenosis were used as positive and negative controls, respectively. Results. Positive reaction for Neu5Gc was observed in intact epoxy-treated xenopericardium and BHVs excised 1, 2, 20 and 42 days after implantation. The tissue of BHV that had lasted 30 months was characterized by the faint presence of Neu5Gc. In the leaflets of AV and in BHVs, explanted after 34, 63 and 68 months, Neu5Gc was not detected. Conclusion. Stabilization of xenobiomaterial with ethylene glycol diglycidyl ether does not remove the Neu5Gc. This saccharide remains in the biological tissue of epoxy-treated BHV for about 2.5 years after implantation.

A full-scale study of the physical and mechanical properties of a number of samples of commercial biomaterials-patches was carried out. It is shown that all materials have a pronounced non-linearity of behavior, manifested in the presence of an initial gentle stress section with a subsequent increase in stiffness, however, there are quantitative differences in the length of these sections and, accordingly, in the final characteristics: tensile strength, elongation at break, elasticity. The results of numerical verification of the obtained coefficients of hyperelastic materials models showed high convergence with the results of field tests. Keywords: numerical modeling, physical and mechanical tests, hyperelastic material model, polynomial approximation.. Keywords: numerical simulation, physical and mechanical testing, hyperelastic material model, polynomial approximation.

Highlights. Non-invasive method for the assessment of the mobility and deformation of the wire element of the bioprosthesis in the cardiac cycle based on the developed mathematical algorithm is presented. Numerical analysis of the behavior of the wire element of the “TiAra” bioprosthesis is shown for the first time. The developed method can be used for other medical devices as well.Aim. To develop a method for non-invasive assessment of the mobility and deformation of the wire element of the aortic heart valve bioprosthesis in the cardiac cycle based on mathematical processing of visual medical data.Methods. Multidetector computed tomography data of patient P. (male, 66 years old), who received the “TiAra” aortic bioprosthesis (NeoCor CJSC, Kemerovo), were used for the study. Using the built-in tools in the Mimics Medical Image Processing Software (Materialize, Belgium), based on the radio density, 5 stages of movement of the wire element of the bioprosthesis were reconstructed in the form of 3D-models. The differences between the models, characterizing deformation in the cardiac cycle, were quantitatively assessed using a proprietary Matlab algorithm (The MathWorks, USA), calculating the distance between similar points. Moreover, obtained data on displacements was used in the numerical study of the stress-strain state of a 3D-model of the wire element by the finite element method in the Abaqus/CAE software (Dassault Systèmes SE, France).Results. The proposed method for assessing the mobility of the wire element made it possible to quantitatively evaluate the biomechanics of the “TiAra” stentless bioprosthesis based on multidetector computed tomography, a non-invasive clinical tool. The movements that the bioprosthesis undergoes during the cardiac cycle (the maximum value is 2.04 mm in the radial direction) are comparable to the movement of the aortic root of a healthy patient. The results of the numerical modeling of the stress state of the wire element did not indicate high amplitudes (peak value – 564 MPa) that would be capable of causing critical damage to the wire. It allows us to confirm the clinical safety of the bioprosthesis in real conditions like asymmetric and uneven loads. Moreover, deformations observed in the bioprosthesis are similar in the amplitude to the displacements of the aortic root described in the literature, which highlights the main feature of the bioprosthesis – ensuring the physiological biomechanics throughout the cardiac cycle.Conclusion. The presented method of qualitative computer assessment of the movement of the wire element of heart valve prosthesis using the “TiAra” bioprosthesis as an example demonstrates its validity as a tool for studying prosthesis functioning.

A full-scale study of the physical and mechanical properties of a number of samples of commercial biomaterials-flaps was carried out. It is shown that all materials have a pronounced non-linearity of behavior, manifested in the presence of an initial gentle stress section with a subsequent increase in stiffness, however, there are quantitative differences in the length of these sections and, accordingly, in the final characteristics: tensile strength, elongation at break, elasticity. The results of numerical verification of the obtained coefficients of hyperelastic materials models showed high convergence with the results of field tests. Keywords: numerical modeling, physical and mechanical tests, hyperelastic material model, polynomial approximation.