Numerical modeling and analysis of cardiac stent using blood hammer principle

Abstract

BACKGROUND:

Atherosclerosis is a condition which disrupts blood flow due to plaque build-up inside the arteries. Under conditions where consecutive plaques are prevailing blood hammer principle is exhibited.

OBJECTIVE:

The pressure and shear stress produced at an infinitesimal area act as the governing equation for stent modeling. The leading order pressure lays the foundation for the design of cardiac stents with definite dimensions.

METHOD:

The designed stent was encapsulated inside a crimper validated through ANSYS-static and transient structural simulation to derive the total deformation, equivalent strain, and stress exerted on the stent. Five different biomaterials stainless steel 316, cobalt, chromium, platinum, and Poly lactic acid were selected for the material assessment.

RESULT:

Static and Transient structural analysis for a period of 1 and 10 secs was implemented for a stent with and without a crimper. The material performance in terms of total deformation, equivalent stress, and strain are analyzed.

CONCLUSION:

The paper envisions the dynamics of blood hammer in atherosclerosis that provides the changes in the pressure and clotting process. It shows the promising results of the stent behavior in varied forces which gives valuable insights for future improvement in stent design and material selection.

1. Introduction

Atherosclerosis is a chronic inflammatory disease in which there is a stockpile of plaques inside arteries. When the endothelium undergoes injury, it allows the collection of fat deposits that upon piling up form plaque which ultimately blocks the artery, and disrupts the blood flow thus leading to complications. When there is even a small deformation such as blockage of the vessels, or leakiness of the valves, it leads to various cardiovascular diseases such as hyperlipidemia, coronary artery disease, varicose veins, deep vein thrombosis, etc. The cohesion between all these diseases is the blockage of vessels that causes a lack of blood flow through the organ system which upon intensification increases the risk of myocardial infarction or heart attack. According to WHO report, as of 2019, there were an estimated 17.9 million deaths due to cardiovascular disease which represents about 32% of all global deaths. Among these 85% of deaths are mainly due to heart attacks and strokes. There is a decrease in cardiovascular mortality globally between 1990–2010. It could be observed that the absolute number of Atherosclerotic Cardiovascular Disease deaths is increasing due to the current unhealthy lifestyle.

The events of atherosclerosis occur inside the artery exactly in the sub-endothelial space. An elevated level of Low-Density Lipoprotein becomes the major risk factor for atherosclerosis genesis. LDL accumulates within the wall and gets modified into oxidized LDL. When the endothelial cells of the lumen encounter an injury, they start recruiting monocytes and also express the adhesion molecules Vascular Cell Adhesion Molecule (VCAM 1), which sticks the monocyte to the endothelium. Monocytes migrate to the sub-endothelial space between Intima and Media through diapedesis, where the monocytes get squeezed between the endothelium. The oxidized LDL enters the intima region where the monocytes get proliferated into macrophages, that engulf the LDL thus forming cholesterol-engorged foam cells. With time, foam cells undergo apoptosis thus leaving behind the cholesterol deposits and cell debris in the form of a necrotic core. Lesions of fat deposits pile up and form plaque which upon intensification ruptures the arterial wall. Figure 1 is the atherosclerosis progression in an artery with its consequences.

Figure 1.

Atherosclerosis progression.

1.1. Graphical abstract

Statins are utilized as a primary therapy that can reduce atherosclerosis and its consequences. Some other therapies include antiplatelet therapy and antihypertensive therapy. Other treatments for atherosclerosis are the use of blood thinners and allografting. However, the above-mentioned treatment methods and therapies do not address the entire atherosclerotic progression followed by a blood clot, as these therapies can provide short-term comfort. Hence this creates a need to fulfil the condition of the dual clot.

Blood hammer is a condition that governs atherosclerosis. As the term blood hammer suggests, when a nail is being inserted by a hammer, the oscillatory motion of the hammer reduces the area of the surface which ultimately leads to an acute rise in pressure due to the sudden load of the hammer. Comparing this with the atherosclerotic condition of an artery, where the inner arterial wall is piled up by atherosclerotic plaques it reduces the area and suddenly increases the pressure inside the vessel, thus constricting the blood flow. This in turn activates platelets that recruit Prothrombin and the clotting factors convert Prothrombin to Thrombin thus leading to vasoconstriction. Thrombin converts Fibrinogen to Fibrin finally leading to blood clots. Atherosclerosis starts with fatty streaks formation and progresses with atheroma and atherosclerotic plaque formation. Hypercholesterolemia, LDL increase, HDL decrease, lipid oxidation, hypertension, malproduction and dysfunction of NO, and inflammation are the most facilitating factors for atherosclerosis. Time sequence functional stents were studied in detail. This review summarizes the evolution of vascular stents. The concept of ‘time sequence functional stent is explained in terms of its antiproliferative properties and support endothelialization and the non-release of toxic degradation products [1]. The FE method is a numerical technique used to obtain approximate solutions for systems of differential or integral equations applied over domains of complex shape. FE analysis has been done widely for this study. Computational numerical methods such as the FE method have emerged as essential and widely adopted tools for the assessment and optimization of biomedical devices such as coronary stents. The use of patient-derived arterial models in conjunction with constitutive material models, capable of capturing the non-linear, anisotropic behavior of diseased and non-diseased arterial tissue, has the potential to provide a scientific basis for the identification and optimization of suitable stent geometries and materials in the treatment of CAD on a patient-specific basis [2]. The article mainly covers the risk factors like cigarette smoking, hypertension, diabetes, serum cholesterol, etc that are associated with atherosclerosis. The new drug targets like the Endoglin receptor, Cholesteryl ester transfer protein inhibitors, Squalene synthase inhibitors, cytochrome P450, Omega-3 Fas, etc that are used in recent times are also studied widely. Nowadays many therapies like HMG CoA reductase inhibitors, are successfully implicated to treat altered lipid profiles associated with atherosclerosis. The review mainly gives the idea about the recent receptor and signaling pathways that take part in the starting stage of atherosclerosis formation [3]. This article discusses Atherosclerotic Plaque Formation Blood Coagulation and Fibrin Formation in Atherosclerosis. Fibrin is a major component of thrombi formed on the surface of atherosclerotic plaques. Fibrin accumulation because of local blood coagulation activation occurs inside atherosclerotic lesions and contributes to their growth. The pro-thrombotic fibrin clot phenotype has been reported to have a predictive value regarding myocardial infarction, ischemic stroke, and acute limb ischemia. Fibrin is a major component of thrombi formed on the surface of atherosclerotic plaques. Fibrin accumulation as a consequence of local blood coagulation activation occurs inside atherosclerotic lesions and contributes to their growth. The pro-thrombotic fibrin clot phenotype has been reported to have a predictive value regarding myocardial infarction, ischemic stroke, and acute limb ischemia [4]. In this paper, the Glass-fibre-filled PA66 gears with the different glass fiber content using the injection molding. The angle of the pressure drive-side was varied from 20^∘ to 35^∘ in steps of 5^∘. Under constant speed and unlubricated conditions, bending fatigue testing was conducted. There is a 23% increase in fatigue life when the pressure angle is increased in the fatigue life for PA66/40GF gears. The gear with a 20–35^∘ gear profile shows good performance in bending with stress levels ranging from 13.11 MPa to 32.76 MPa. This gear was unstable with the cross 10⁶ stress cycles at a torque of 2 Nm. The addition of glass fiber and increased driving-side pressure angle improved the fatigue performance of the polymer gears. An experimental investigation hasn’t been conducted to determine the impact of glass fiber content combined with different combinations of pressure angles [5]. Atherosclerosis starts with fatty streaks formation and progresses with atheroma and atherosclerotic plaque formation. Hypercholesterolemia, LDL increase, HDL decrease, lipid oxidation, hypertension, malproduction and dysfunction of NO, and inflammation are the most facilitating factors for atherosclerosis. Atherosclerosis starts with fatty streaks formation and progresses with atheroma and atherosclerotic plaque formation. Hypercholesterolemia, LDL increase, HDL decrease, lipid oxidation, hypertension, malproduction and dysfunction of NO, and inflammation are the most facilitating factors for atherosclerosis [6]. This paper is about developing a material that can be molded into edible straws as a replacement for plastic straws. 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The degradation study suggests that PLA could be a preferred material for replacing river sand [11]. This study has analyzed a single segment of stiffened coronary artery due to sudden blockage which is called a “Blood Hammer” and the relation between mechanical and rheological parameters in vascular occlusion. Also, this paper has analyzed various dimensions of vascular occlusion for different blood clots by studying the changes in oscillating pressure, velocity, wall shear stress, and skin friction coefficient [12]. The paper focuses on the aeroelastic impact validation of wing trailing edge morphing using bio-inspired structures. The analysis is conducted using ANSYS CFX to demonstrate the aerodynamic efficiency of the morphing concept compared to conventional wing-flap configurations. The maximum displacement at a 30-degree deflection is 47.45 mm, while the maximum stress is 21 MPa. 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The method presented in this paper can be used to predict stresses in the stent struts and the vessel wall, and thus evaluate whether a specific stent design is optimal for a specific patient [14]. One-year success after coronary stenting is limited mainly by restenosis and the requirement for repeat revascularization of the treated lesion. Clinical restenosis was defined using three different definitions: target lesion revascularization (TLR) beyond 30 days, target vessel revascularization (TVR) beyond 30 days, and target vessel failure (TVF), defined as TVR, any death, or myocardial infarction (MI) of the target vessel territory after hospital discharge. At one year after stenting, most clinical restenosis reflected TLR, which was predicted by the same variables previously associated with an increased risk of angiographic restenosis. 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2. Materials and methods

Traditional cardiac stents are being manufactured using stainless steel 316L, Cobalt, Chromium, platinum, poly lactic acid widely. Metal stents are most available in the markets comparing to other material stents as they have shown the best properties and long life. We have designed our stent for atherosclerotic conditions using the principle of blood hammer.

According to the principle of blood hammer provided by the literature Chiang C. Mei et al., where there is an acute rise in pressure, the equation of leading order pressure which is exerted on the artery is:

$P_0(x,t)={\displaystyle \frac{1}{2\pi i}}{\displaystyle \underset{C}{\int }}ds{\displaystyle \frac{e^{st}\sin hsx}{s\cos hs}}\overline{D_S}$ (1)

where $C$ is a straight contour to the right of the poles on the imaginary axis in the complex plane $s$ and,

$\overline{D_S}={\displaystyle \frac{1}{t_o^2}}{\displaystyle \frac{{(1-e^{-s{t}_o})}^2}{s^2}}$ (2)

is the Laplace transform of $D(t)$.

There are simple poles in the complex planes at $s=i\left(m+\frac{1}{2}\right)\pi$, $m=$ 0, 1, 2, etc.

From Cauchy’s theorem, the residues at $s=i{k}_m$ is,

${\displaystyle \frac{e^{i{k}_{m}t}\sin k_{m}x}{i{k}_m\sin k_m}}{D}_m$ (3)

Where

$D_m=-{\displaystyle \frac{1}{t_o^2{k}_m^2}}{(1-e^{-i{k}_m{t}_o})}^2$

The solution of the above equation is given by

$P_o(x,t)=-{\displaystyle \sum _{m=-\mathrm{\infty }}^{\mathrm{\infty }}}{P}_m(T){\displaystyle \frac{e^{i{k}_{m}t}\sin k_{m}x}{i{k}_m\sin k_m}}{\displaystyle \frac{{(1-e^{-i{k}_m{t}_o})}^2}{k_m^2{t}_o^2}}$ (4)

with the initial condition $P_m(1)=0$.

Here, $T=\epsilon$, such that

$\epsilon =\sqrt{{\displaystyle \frac{\vartheta L}{C_o}}}{\displaystyle \frac{1}{R_o}},$ (5)

where, $\vartheta$ is the viscous shear of blood approximately equal to 4*10 ^{- 2} cm²/s. $C_o$ is the wave speed in an artery equal to 2*10⁴ m/s. $R_o$ is the radius of the artery before plaque formation equal to 1.9 mm. $L$ is the length of the artery assumed to be 15.1 mm which is the length of the designed stent.

Substituting the above values in the equation of $\epsilon$, the value of $\epsilon =9.14\ast {10}^{-4}$.

Taking the following assumptions: $t=$ 0 s, $m=$ 0, $x=$ 1, $t_o=$ 1 s and substituting in the main solution equation of the leading order pressure,

$P_o(x,t)={\displaystyle \frac{{\left(1-e^{-i\frac{\pi }{2}}\right)}^2}{i\frac{{\pi }^3}{8}}}$ (6)

Solving this the leading order pressure is $P_o=$ 0.5160 Pa.

We know that $\text{𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒}=\frac{\text{𝐹𝑜𝑟𝑐𝑒}}{\text{𝐴𝑟𝑒𝑎}}$ and here Area is the reduced area of artery in the presence of atherosclerotic plaque.

Assuming that 75% of the area is covered by plaque, the remaining area through which blood can flow would be

$\text{𝐴𝑟𝑒𝑎}=0.25(\pi R_o^2)=2.833\ast {10}^{-6}{\text{m}}^2.$ (7)

Hence the force that is exerted on an atherosclerotic artery is 1.46*10 ^{- 6} N.

After deriving the force value as 1.46*10 ^{- 6} N, the cardiac stent design was created with the dimensions of length as 15.1 mm, diameter as 3.8 mm, and thickness as 0.14 mm using SOLIDWORKS^® 2020 in Windows core i3. The procedure for designing the stent is as follows In Solidworks, Part design was chosen as the first step. Next, as the cross-sectional diameter of an artery usually ranges from 1 to 10 mm, fixing 3.8 mm as diameter, a circle was outlined. Then, to generate a tubular helical spiral, a circle was sketched on the reference plane for a diameter of 0.14 mm which marks the thickness of the stent. Through the use of features, the circle and the helix axis are selected and a sweep tool is used that sweeps the circle thus giving the required tubular structure. The above steps are again followed thus creating another helical spiral in the counterclockwise direction. The created spirals must be looped to create a pattern to get the stent. To proceed with further analysis, the stent was encapsulated in a crimper. Using the Features tool, circles are extruded, which creates the cylindrical structure of crimper around the stent. Figure 2 shows the designed cardiac stent with and without a crimper using Solidworks. After designing the cardiac stent, the static structural and transient structural analysis was done using ANSYS inc, an engineering simulation software. The procedure for ANSYS is as follows: Fig. 3 explains the procedure of static structural analysis. The same was done for transient structural analysis with 10S as the period limit. The research focuses on ductile materials and has the constraint or limitation of not focussing on the brittle material which can done in future works.

Figure 2.

Designed cardiac stent with and without crimper.

Figure 3.

Schema of workflow.

3. Results and discussion

The data provided presents a comprehensive comparison of various materials, including Stainless Steel, Cobalt, Chromium, Platinum, and PLA, based on a range of critical properties. These properties encompass density, stiffness (Young’s Modulus), resistance to compression (Bulk Modulus), shear strength, lateral deformation characteristics (Poisson’s Ratio), tensile strength (both yield and ultimate), elastic modulus, thermal expansion behavior, and compressive yield strength. This information is vital for material selection in engineering and manufacturing, as it allows us to make informed choices based on specific needs. For instance, Cobalt and Chromium exhibit high stiffness and strength, making them suitable for applications requiring robust materials, while Platinum and PLA are more flexible but also less dense. The data empowers engineers and designers to select materials tailored to their research requirements, ensuring optimal performance and durability in various scenarios.

Table 1.

Properties of different materials

Properties	Stainless steel	Cobalt	Chromium	Platinum	PLA
Density (Kg/m3)	8090	8900	7140	21450	1240
Young’s modulus (Pa)	193*109	199*109	140*109	154*109	1.28*109
Bulk modulus (Pa)	163*109	174*109	160*109	222*109	4.8*109
Shear stress (Pa)	62*109	74*109	115*109	62*109	1.287*109
Poisson’s ratio	0.3	0.32	0.21	0.39	0.36
Tensile yield strength (Pa)	205*106	225*106	370*106	120*106	70*106
Tensile ultimate strength (Pa)	515*106	800*106	550*106	150*106	59*106
Elastic modulus (Pa)	200*109	211*109	270*109	171*109	3500*109
Coefficient of thermal expansion	16.6*10 - 6	12*10 - 6	3.3*10 - 6	9*10 - 6	41*10 - 6
Compressive yield strength (Pa)	170*106	295*106	1275.53*106	96.52*106	65*106

3.1. Static structural analysis

3.1.1. Cardiac stent without crimper

The static structural analysis is important for understanding how the stent behaves under various conditions and loads. The parameters measured include Total Deformation, Equivalent Strain, and Equivalent Stress for five different materials: Stainless Steel, Cobalt, Chromium, Platinum, and PLA tabulated in Table 5 and Fig. 4. In terms of Total Deformation, it is evident that all materials display less deformation. The maximum deformation observed in these stents ranges from 1.7844e-5 mm to 4.4901e-5 mm. This minimal deformation is good, these stents can maintain their structural integrity and original shape when subjected to external forces. Such stability is of utmost importance in a cardiac stent, as it must maintain its shape to effectively support a patient’s blood vessel. Equivalent Strain, a measure of the material’s deformation, shows that the strains across the different materials remain relatively low, with the maximum values ranging from 1.6671e-6 mm to 3.7206e-6 mm. This suggests that the materials used in these stents have good elasticity, meaning they can deform slightly under stress and then return to their original shape. In the context of cardiac stents, this elasticity is beneficial as it allows the stent to adapt to the shape of the blood vessel, providing necessary support while minimizing damage to the vessel walls. Equivalent Stress, which reflects the stress distribution in the stent, indicates that the materials exhibit varying levels of stress. The maximum stress levels range from 0.31515 MPa to 0.70394 MPa. Lower stress levels are generally desirable in medical devices like cardiac stents to avoid overstressing the surrounding tissue, which could lead to complications. Stainless Steel and Cobalt exhibit relatively high stress, while Platinum and PLA show lower stress values. The choice of material may depend on the specific requirements of the stent, such as its location in the cardiovascular system and the patient’s individual needs. These materials exhibit minimal deformation, low strain, and varying levels of stress, making them suitable for different cardiac stent applications. The choice of material should be carefully considered, factors like patient-specific needs, the stent’s location, and the desired level of structural integrity and elasticity. The cardiac stent designed without crimper is shown in the Fig. 4.

Figure 4.

Static structural of stainless steel, cobalt, chromium, platinum & PLA stent without crimper.

3.1.2. Cardiac stent with crimper

The analysis is essential for assessing how these stents perform under various conditions and loads, and the data includes parameters such as Total Deformation, Equivalent Strain, and Equivalent Stress for five different materials: Stainless Steel, Cobalt, Chromium, Platinum, and PLA shown in Table 5 and Fig. 5. Total Deformation is a key parameter in understanding how much these stents deform under different stresses. In this case, all the materials exhibit minimal deformation, with maximum values ranging from 9.8752e-5 mm to 0.0058041 mm. This suggests that these stents can maintain their structural integrity and original shape even when subjected to external forces. Maintaining their shape is crucial for cardiac stents as it ensures they effectively support the patient’s blood vessels without causing excessive distortion. Equivalent Strain, which measures the material’s deformation, indicates that the strains in these materials are relatively low. The maximum values of Equivalent Strain range from 4.2621e-6 mm to 0.00028926 mm. This low level of strain suggests that the materials used in these stents possess good elasticity. They can deform slightly under stress and then return to their original shape. This characteristic is highly desirable for cardiac stents as it enables them to adapt to the shape of the blood vessel, providing support while minimizing damage to the vessel walls. Equivalent Stress reflects the distribution of stress within the stent. The maximum stress levels range from 0.19333 MPa to 0.78953 MPa.

Figure 5.

Static structural of stainless steel, cobalt, chromium, platinum & PLA stent with crimper.

Lower stress levels are generally desirable in medical devices like cardiac stents to avoid overstressing the surrounding tissue, which could lead to complications. Stainless Steel exhibits the lowest stress, followed by Chromium, Platinum, and Cobalt, while PLA shows the highest stress levels. The choice of material should be carefully considered based on factors such as the stent’s intended location in the cardiovascular system and the patient’s individual needs. Static structural analysis of cardiac stents designed with a crimper indicates that these materials experience minimal deformation, low strain, and varying stress levels. These characteristics make them suitable for different cardiac stent applications. However, the choice of material remains a critical decision, depending on the specific requirements of the stent, including its location within the cardiovascular system, the patient’s unique needs, and the desired level of structural integrity and elasticity. These findings contribute to ongoing improvements in cardiac stent design, ensuring the safety and efficacy of these life-saving medical devices.

Table 2.

Static structural analysis of stent without crimper

Parameters	Stainless steel		Cobalt		Chromium		Platinum		PLA
	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum
Total deformation (m)	0	4.4901*10 - 8	0	1.7844*10 - 8	0	1.8704*10 - 8	0	1.1944*10 - 8	0	2.333*10 - 8
Equivalent strain (m)	2.256*10 - 15	3.7206*10 - 9	1.406*10 - 14	1.6671*10 - 9	3.2578*10 - 13	1.9449*10 - 9	5.23*10 - 15	2.4082*10 - 9	3.698*10 - 14	2.6831*10 - 9
Equivalent stress (Pa)	0.11857	703940	2.484	315150	30.779	358990	0.89704	412050	7.3974	417740

Table 3.

Static structural analysis of stent with crimper

Parameters	Stainless steel		Cobalt		Chromium		Platinum		PLA
	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum
Total deformation (m)	0	1.1987*10 - 9	0	9.8752*10 - 8	0	5.7348*10 - 8	0	4.5886*10 - 8	0	5.8041*10 - 6
Equivalent strain (m)	3.374*10 - 17	1.075*10 - 9	3.055*10 - 14	4.2621*10 - 9	2.642*10 - 14	2.7365*10 - 9	2.642*10 - 14	2.4384*10 - 9	2.642*10 - 14	2.8926*10 - 7
Equivalent stress (Pa)	0.0065067	193330	0.46229	789530	2.8002	377940	2.8002	369850	2.8002	369230

Table 4.

Transient structural analysis of stent without crimper

Parameters	Stainless steel		Cobalt		Chromium		Platinum		PLA
	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum
Total deformation (m)	0	3.2009*10 - 6	0	1.793*10 - 8	0	2.6004*10 - 8	0	1.7419*10 - 8	0	2.1041*10 - 6
Equivalent strain (m)	4.865*10 - 16	2.9666*10 - 7	1.335*10 - 18	1.9978*10 - 9	6.461*10 - 19	2.7241*10 - 9	5.747*10 - 18	2.0776*10 - 9	4.936*10 - 16	2.5627*10 - 7
Equivalent stress (MPa)	0.00051697	370550	0.00025892	364790	7.8726*10 - 5	358470	0.00079086	297510	0.00055666	304940

Table 5.

Transient structural analysis of stent with crimper

Parameters	Stainless steel		Cobalt		Chromium		Platinum		PLA
	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum	Minimum	Maximum
Total deformation (m)	0	1.1826*10 - 9	0	1.1642*10 - 9	0	1.7199*10 - 8	0	4.5124*10 - 8	0	4.3568*10 - 6
Equivalent strain (m)	2.445*10 - 20	1.0728*10 - 9	2.728*10 - 17	9.891*10 - 10	0	3.0653*10 - 9	0	2.5035*10 - 9	0	1.8298*10 - 7
Equivalent stress (Pa)	1.5683*10 - 6	193460	0.0035697	0.18459	0	251350	0	383200	0	618280

3.2. Transient structural analysis

3.2.1. Cardiac stent without crimper

The analysis aims to understand how these stents respond to dynamic loads over time. The parameters examined include Total Deformation, Equivalent Strain, and Equivalent Stress for five different materials: Stainless Steel, Cobalt, Chromium, Platinum, and PLA tabulated in the Table 5 and Fig. 6. Total Deformation is a critical parameter to assess how much these stents deform under dynamic loads. The maximum deformation values range from 1.793e-5 mm to 0.0032009 mm. These results suggest that under transient loading conditions, these stents exhibit a significantly higher degree of deformation compared to the static analysis. This behavior may be due to the stent being exposed to varying forces and movements within the cardiovascular system over time. It’s crucial to evaluate the implications of such deformation on the stent’s performance and its effect on the surrounding tissue. Equivalent Strain, which measures the material’s deformation, demonstrates that the materials in these stents undergo relatively low strain. The maximum values of Equivalent Strain range from 1.9978e-6 mm to 0.00029666 mm. These strains indicate that the materials used in these stents retain their elasticity, with slight deformations under dynamic loads. This elasticity is crucial for cardiac stents as it allows them to accommodate variations in the blood vessel’s shape during the cardiac cycle. Equivalent Stress reflects the distribution of stress within the stent. The maximum stress levels range from 0.29751 MPa to 0.37055 MPa. Lower stress levels are generally preferred in medical devices like cardiac stents to minimize the risk of damaging surrounding tissue. The materials respond differently to transient loading, with Cobalt and Stainless Steel showing higher stress levels, while Platinum and Chromium exhibit lower stresses. PLA, however, shows slightly higher stress levels, which may raise concerns regarding its suitability for dynamic applications. The transient structural analysis of cardiac stents designed without a crimper reveals that these materials experience increased deformation and varying stress levels under dynamic loads. The choice of material remains a critical decision, and factors such as the stent’s intended location in the cardiovascular system, the patient’s unique needs, and the desired level of structural integrity and elasticity must be considered. These findings provide valuable insights into how these stents perform under real-world conditions and contribute to the ongoing improvement of cardiac stent design, ensuring their safety and efficacy in dynamic cardiovascular environments. Further analysis and testing may be necessary to determine the long-term behavior and performance of these stents in vivo.

Figure 6.

Transient structural of stainless steel, cobalt, chromium, platinum & PLA stent without crimper.

Figure 7.

Transient structural of stainless steel, cobalt, chromium, platinum & PLA stent with crimper.

Analysis is essential for assessing how these stents perform under dynamic loads over time, and it includes parameters such as Total Deformation, Equivalent Strain, and Equivalent Stress for five different materials: Stainless Steel, Cobalt, Chromium, Platinum, and PLA tabulated in Table 5 and Fig. 6. Total Deformation is a crucial parameter for understanding how much these stents deform under dynamic loads. The maximum deformation values range from 1.1642e-6 mm to 0.0043568 mm. These results indicate that the stents, even when designed with a crimper, exhibit relatively low deformation under transient loading conditions. This stability is an important characteristic, as it ensures that the stent can maintain its structural integrity and provide consistent support to the patient’s blood vessel, even when subjected to variations in forces and movements. Equivalent Strain, which measures the material’s deformation, demonstrates that the materials in these stents undergo relatively low strain, with maximum values ranging from 9.8912e-7 mm to 0.00018298 mm. These low strain values indicate that the materials possess good elasticity, allowing them to adapt to variations in the blood vessel’s shape during the cardiac cycle. This elasticity is crucial for cardiac stents, as it enables them to provide the necessary support without causing significant deformation or stress on the surrounding tissue. Equivalent Stress reflects the distribution of stress within the stent. The maximum stress levels range from 0.18459 MPa to 0.61828 MPa. These stress levels are generally desirable in medical devices like cardiac stents, as they minimize the risk of damaging the surrounding tissue. Stainless Steel, Cobalt, and Chromium exhibit lower stress levels, while Platinum and PLA show slightly higher stresses. These variations may influence the choice of material, depending on the specific needs of the stent and its intended location within the cardiovascular system. In summary, the transient structural analysis of cardiac stents designed with a crimper reveals that these materials exhibit low deformation, low strain, and varying stress levels under dynamic loads. The choice of material remains a critical decision, and factors such as the stent’s intended location in the cardiovascular system, the patient’s unique needs, and the desired level of structural integrity and elasticity must be considered. These findings provide valuable insights into how these stents perform under real-world, dynamic cardiovascular conditions, ensuring their safety and efficacy in providing support to patients. Further analysis and testing may be necessary to determine the long-term behavior and performance of these stents in actual clinical settings.

4. Conclusion

Global statistics on cardiovascular diseases show that there is a need for innovative solutions to compensate for the widespread. Approximately 17.9 million people are lost per year due to cardiovascular diseases and coronary artery disease ranks as the third cause of mortality so effective interventions are crucial. This research focuses on the design of cardiac stents specifically tailored for atherosclerotic conditions which addresses the critical aspect of cardiovascular care. Its emphasis is on ductile materials for stent construction and has the constraint that the research needs to focus on brittle materials in the future. Through the rigorous analysis and the comparison of the properties of material stainless steel is identified as the optimal choice and also recommended by the clinicians as the easy placement and the biocompatible works efficiently. Integrating theoretical insights, engineering design principles, and clinical feed it offers valuable contributions to healthcare. In future the continued research and collaboration will be essential in stent design and improve patient outcomes in the fight against cardiovascular diseases.

Data availability statement

The author declares that there is no usage of the dataset for this research and hence there is no dataset repository available for this paper.

Ethical statement

None.

Conflict of interest

The authors declare that there are no conflicts of interest regarding the publication of this paper. The authors have no financial or personal relationships that could influence the research outcomes or the interpretation of the data presented in this manuscript.