Stent Design Research Articles

Biodegradable Multi-layered Silk Fibroin-PCL Stent for the Management of Cervical Atresia: In Vitro Cytocompatibility and Extracellular Matrix Remodeling In Vivo.

Cervical atresia is a rare congenital Müllerian duct anomaly that manifests as the absence or deformed nonfunctional presence of the cervix. Herein, a multi-layered biodegradable stent is fabricated using a homogeneous blend of silk fibroin with polycaprolactone using hexafluoroisopropanol as a common solution. Briefly, a concentric cylinder of 3D honeycomb layer is sandwiched within electrospun sheets for fixing at the cervico-uterine junction to pave the way of cervical reconstruction. An average length of 40 mm with 3 mm diameter is fabricated for the hybrid stent design. SEM evidences an evenly distributed pore architecture of the electrospun layer, and mechanical characterization of stent reveals a tensile strength of 1.7 ± 0.2 MPa, with a Young's modulus of 5.9 ± 0.1 MPa. Physico-chemical characterization confirms the presence of silk fibroin and poly caprolactone within the engineered stent. Following 14 days of pepsin enzymatic degradation, 18% degradation and a contact angle measurement of 97° are observed. In vitro cytocompatibility studies are performed using site-specific primary human cervical squamous, columnar epithelial cells, and human endometrial stromal cells. The study demonstrates non-cytotoxic cells' viability (no significant toxicity), improved cell anchoring, adherence among the stent layers, and proliferation in the 3D microenvironment. Furthermore, in vivo subcutaneous studies in the rodent model indicate that the implanted stent undergoes constructive remodeling, neo-tissue creation, neo-vasculature formation, and re-epithelialization while maintaining patency for 2 months.

Design of innovative self-expandable femoral stents using inverse homogenization topology optimization

In this study, we propose a novel computational framework for designing innovative self-expandable femoral stents. First, a two-dimensional stent unit cell is designed by inverse homogenization topology optimization. In particular, the unit cell is optimized in terms of contact area with the target of matching prescribed mechanical properties. The topology optimization is enriched by an anisotropic mesh adaptation strategy, enabling a time- and cost-effective procedure that promotes original layouts. Successively, the optimized stent unit cell is periodically repeated on a hollow cylindrical surface to construct the corresponding three-dimensional device. Finally, structural mechanics and computational fluid dynamics simulations are carried out to verify the performance of the newly-designed stent. The proposed workflow is being tested through the design of five proof-of-concept stents. These devices are compared through specific performance evaluations, which include the assessments of the minimum requirement for usability, namely the ability to be crimped into a catheter, and the quantification of the radial force, the foreshortening, the structural integrity and the induced blood flow disturbances.

Clinical Efficacy and Safety of a Novel Stent for Fistula Management Following Sleeve Gastrectomy

Background and AimsManagement of fistulas after bariatric surgery has shifted from a surgical to a primarily endoscopic approach. We aimed to determine the efficacy of a novel stent for the closure of fistulas and stent-related adverse events in patients with fistulas after sleeve gastrectomy (SG). MethodsFifteen patients who developed fistulas following SG between July 2016 and December 2020 and managed at a tertiary care hospital by a primarily endoscopic approach were retrospectively evaluated. The technical and clinical success of a novel stent for the exclusion and definitive closure of fistulas and the need for endoscopic and surgical reinterventions and adverse events were analyzed. ResultsFifteen patients with median age of 47 (20-61) years, 11 (73%) females, were included. Fistulas were located at the cardia in 12 (80%) patients, with a median diameter of 4 (2-15) mm. Concomitant stricture of the gastric tube was detected in 8 (53%) patients. A single stent was placed in 13 (87%) patients. Endoscopic reinterventions were required in 5 (33%), and a surgical toilette was needed for 3 (20%) patients. After a median stent implantation duration of 6 (3-21) weeks, fistula closure was documented in all 15 (100%) patients. The concomitant stricture of the gastric tube that occurred in 8 (53%) patients was also successfully managed. Adverse events related to stent placement or removal occurred in 5 (33%) patients and were managed endoscopically. Stent dysfunction occurred in 1 (7%) patient. One patient died due to bleeding from an aortoesophageal fistula 3 cm above the proximal edge of the stent. ConclusionThe novel stent is effective in closing fistulas after SG. The unique stent design is associated with a low risk of migration, allows for the management of concomitant strictures in the gastric tube, and facilitates stent removal.

Shielding AZ91D-1%Ca from corrosion through ultrasound melt treatment: A study for stent design

Magnesium-based materials show great potential for producing biodegradable stents, but their high corrosion rates are a roadblock.This study investigates whether ultrasound melt treatment can change the corrosion response of an extruded AZ91D-1.0%Ca (wt.%) in Earle's Balanced Salt Solution by tailoring the intermetallics' morphology in the as-extruded state.The results showed that the wires from ultrasound-treated ingots corroded faster than non-treated ones in immersion for up to 6 hours. This trend shifted for longer periods, and ultrasound-treated material showed lower corrosion rates and uniform corrosion, while the non-treated material displayed localized corrosion signs. Tensile testing of the wires demonstrated that immersion in EBSS lowered the tensile strength and elongation at fracture due to material degradation, regardless of the processing route. Nonetheless, this decline was sharper in the non-treated material.These findings suggest that ultrasound melt processing can be a promising method for improving the corrosion resistance of magnesium-based materials, paving the way for their use in manufacturing biodegradable stents.

Fatigue strength and life prediction of lower limb venous stents under three-stage loading conditions

After the implantation of lower limb artery stents, the complex loading conditions imposed on the limb can lead to fatigue failure, which may induce inflammation and restenosis. To investigate the effect of multi-axial loading conditions on the fatigue performance of stents, five stents, namely APsolute Pro (APbott Vascular, USA), Complete SE (Medtronic, USA), Protégé EverFlex (PE3, USA), Pulsar-35 (Biotronik, Germany), and E-luminexx-B (Bard, USA), were analyzed based on the finite element method (FEM). Besides, their fatigue strength was determined under three levels of loading conditions, including tension-bending-torsion and compression-bending-torsion. Based on that, the fatigue life of these stents was predicted. The results showed that based on the nominal stress method, tension-bending-torsion loading had a more significant impact on the fatigue life of stents than compression-bending-torsion loading. Besides, two different types of initial cracks were analyzed by the fracture mechanics method. The results suggested that both the initial crack and the external load were the main causes of stent fatigue fractures. Compared with the loading nature, the influence of the initial crack on stent fatigue life was more significant. Under the same loading condition, the APsolute Pro stent had the longest fatigue life, while the E-luminexx-B stent had the shortest. Moreover, the mechanism of stent fatigue failure was revealed by exploring the fatigue performance and life prediction of stents under complex loading conditions. These findings have important implications for improving the structural design of stents and their clinical selection.

Material Characteristic of an Innovative Stent for the Treatment of Urethral Stenosis

Abstract The appropriate development and customisation of the stent to the urethral tissues requires the determination of many factors such as strength and degradation. Given the distinctive conditions of urethral tissues, it is important that the design of the stent be properly developed. The selection of a stent material requires knowing its material characteristics and verifying that they are suitable for the future implantation site. In the present study, the development of a polydioxanone (PDO)-based stent was undertaken. The PDO material was fabricated using an additive technique – 3D printing. Then, in vitro tests were performed to determine the degradation time of the material under conditions simulating an aggressive urinary environment. The changes in the parameters of mechanical properties before and after the degradation period were determined, and the changes in the structure of the material before and after degradation were observed. Numerical analysis was performed for the proposed stent design. The results showed that PDO has good mechanical properties, but its degradation time is too short to be used in a urethral stent. Among the innovations of the studies conducted are bending strength tests, which is not a frequently considered aspect so far.

Adaptation of Vascular Smooth Muscle Cell to Degradable Metal Stent Implantation.

Iron-, magnesium-, or zinc-based metal vessel stents support vessel expansion at the period early after implantation and degrade away after vascular reconstruction, eliminating the side effects due to the long stay of stent implants in the body and the risks of restenosis and neoatherosclerosis. However, emerging evidence has indicated that their degradation alters the vascular microenvironment and induces adaptive responses of surrounding vessel cells, especially vascular smooth muscle cells (VSMCs). VSMCs are highly flexible cells that actively alter their phenotype in response to the stenting, similarly to what they do during all stages of atherosclerosis pathology, which significantly influences stent performance. This Review discusses how biodegradable metal stents modify vascular conditions and how VSMCs respond to various chemical, biological, and physical signals attributable to stent implantation. The focus is placed on the phenotypic adaptation of VSMCs and the clinical complications, which highlight the importance of VSMC transformation in future stent design.

Conduit design with expanding diameter for enhanced flow

Conduits are commonly used for treating lesions in arteries and veins. The conventional stents are cylindrical in shape, which increases flow resistance with length. This study presents a design of stents and conduits where the conduit caliber expands gradually to reduce resistance while avoiding flow separation. Inflow was provided from a header tank at two different pressures (i.e., 10 and 25 mm Hg pressure) into a cylindrical or expanding conduit. The initial conduit calibers were 2-, 3-, 4-, and 5-mm and 160-, 310-, and 620-mm lengths in each case. The flow rates of expanding caliber conduits (at a rate of r4–6/cm where r is the initial conduit radius) were compared to traditional cylindrical conduits of constant radius. The expanded caliber yields a significantly increased flow of 16–55% for R4/L expansion, 9–44% for R5/L expansion, and 1–28% for R6/L expansion. Simulated flow models using computational fluid dynamics (CFD) were used to validate and expand the experimental findings. Flow separation was detected for certain simulations by flow pathlines and wall shear stress (WSS) calculations. The results showed that a caliber expansion rate of r6/cm is the optimal rate of expansion for most potential applications with minimum flow separation, lower resistance, and increased flow.

Comprehensive mechanical performance characteristics of newly developed ultra-thin coronary stents

Endovascular technologies such as percutaneous transluminal coronary angioplasty and stenting are widely used due to being minimally invasive procedures. One of the endovascular devices, a drug-eluting stent (DES), proved to be a safe and effective therapeutic option for cardiologists, substantially reducing in-stent restenosis (ISR) rates. DES consists of thin (< 200 µm) or ultra-thin (< 70 µm) struts made of Cobalt-Chromium (CoCr) or other alloys. The DES with ultra-thin struts exhibits higher longitudinal flexibility and improved trackability. It also reduces vascular injury and promotes more rapid endothelization, substantially decreasing the risk of ISR. This study evaluates comprehensive mechanical performances of two different structural designs of newly developed ultra-thin CoCr stents (i.e., strut width of 75 µm or 65 µm). These two stent designs are engineered with distinct bridge size and distribution patterns, prioritizing enhanced flexibility irrespective of the strut thickness. Computational modeling results show anticipated stress distribution with maximum local stresses, which are compared with experimental outcomes conducted in this study. ASTM guideline based in vitro experimental studies have been conducted to assess the stents’ longitudinal flexibility, radial strength, recoil and shortening, as well as crushability through this study. Three-point bending experiments have demonstrated that the stent design 1 requires less bending force compared to the design 2, showing better longitudinal flexibility of the stent design 1 in the collapsed state for the new ultra-thin DES devices. The design 1 also showed superior radial strength and recoiling phenomena, as well as smaller shortening. In short, the stent design 1 shows better mechanical performance needed for the coronary artery DES.

Investigation of Stent Prototypes for the Eustachian Tube in Human Donor Bodies.

Chronic otitis media is often connected to Eustachian tube dysfunction. As successful treatment cannot be guaranteed with the currently available options, the aim is to develop a stent for the Eustachian tube (ET). Over the course of this development, different prototypes were generated and tested in ex vivo experiments. Four different prototypes of an ET stent and one commercially available coronary stent were implanted in the ET of seven human donor bodies. The position of the stents was verified by cone beam CT. The implanted ETs were harvested, embedded in resin and ground at 200 µm steps. Resulting images of the single steps were used to generate 3D models. The 3D models were then evaluated regarding position of the stent in the ET, its diameters, amount of squeezing, orientation of the axes and other parameters. Virtual reconstruction of the implanted ET was successful in all cases and revealed one incorrect stent placement. The cross-section increased for all metal stents in direction from the isthmus towards the pharyngeal orifice of the ET. Depending on the individual design of the metal stents (open or closed design), the shape varied also between different positions along a single stent. In contrast, the cross-section area and shape remained constant along the polymeric prototype. With the current investigation, insight into the behavior of different prototypes of ET stents was gained, which can help in defining the specifications for the intended ET stent.

Effect of ureteral stent length and implantation position on migration after implantation.

Ureteral obstruction is a urinary system disease that causes urinary retention, renal injury, renal colic, and infection. Ureteral stents are often used for conservative treatment in clinics, and their migration usually results in ureteral stent failure. The migrations include proximal migration to the kidney side and distal migration to the bladder side, but the biomechanism of stent migration is still unknown. Finite element models of stents with lengths from 6-30cm were developed. The stents were implanted into the middle of the ureter to analyze the effect of stent length on its migration, and the effect of stent implantation position on 6-cm-long stent migration was also observed. The stents' maximum axial displacement was used to assess the ease of stent migration. A time-varying pressure was applied to the ureter outer wall to simulate peristalsis. The stent and ureter adopted friction contact conditions. The two ends of the ureter were fixed. The radial displacement of the ureter was used to evaluate the effect of the stent on peristalsis. The maximum migration occurs in the positive direction for a 6-cm-long stent implanted at the proximal ureter (CD and DE), but in the negative direction at the distal ureter (FG and GH). The 6-cm-long stent demonstrated almost no effect on ureteral peristalsis. The 12-cm-long stent diminished the radial displacement of the ureter from 3-5s. The 18-cm stent diminished the radial displacement of the ureter from 0-8s, and the radial displacement within 2-6s was weaker than other time. The 24-cm stent diminished the radial displacement of the ureter from 0-8s, and the radial displacement within 1-7s was weaker than other time. The biomechanism of stent migration and ureteral peristalsis weakening after stent implantation was explored. Shorter stents were more likely to migrate. The implantation position had less influence on ureteral peristalsis compared with the stent length, which provided a reference for stent design aimed at reducing stent migration. Stent length was the main factor affecting ureteral peristalsis. This study provides a reference for the study of ureteral peristalsis.

Degradable Antimicrobial Ureteral Stent Construction with Silver@graphdiyne Nanocomposite.

In the surgical treatment of urinary diseases, ureteral stents are commonly used interventional medical devices. Although polymer ureteral stents with polyurethane as the main constituent are widely used in the clinic, the need for secondary surgery to remove them and their propensity to cause bacterial infections greatly limit their effectiveness. To satisfy clinical requirements, an electrospinning-based strategy to fabricate PLGA ureteral stents with silver@graphdiyne is innovated. Silver (Ag) nanoparticles are uniformly loaded on the surface of graphdiyne (GDY) flakes. It is found that the incorporation of Ag nanoparticles into GDY markedly increases their antibacterial properties. Subsequently, the synthesized and purified Ag@GDY is homogeneously blended with poly(lactic-co-glycolic acid) (PLGA) as an antimicrobial agent, and electrospinning along with high-speed collectors is used to make tubular stents. The antibacterial effect of Ag@GDY and the porous microstructure of the stents can effectively prevent bacterial biofilm formation. Furthermore, the stents gradually decrease in toughness but increase in strength during the degradation process. The cellular and subcutaneous implantation experiments demonstrate the moderate biocompatibility of the stents. In summary, considering these performance characteristics and the technical feasibility of the approach taken, this study opens new possibilities for the design and application of biodegradable ureteral stents.

Hepatic Encephalopathy following Transjugular Intrahepatic Portosystemic Shunt Placement.

Hepatic encephalopathy (HE) is a complex condition that arises as a complication of chronic liver disease and portosystemic shunting. Its pathophysiology involves several factors, including impaired ammonia metabolism, portosystemic shunting, sarcopenia, and systemic inflammation. The symptoms of HE can vary significantly, with manifestations ranging from subclinical signs to a comatose state. The West Haven classification system is most commonly used to grade the severity of HE. There is a broad differential for the presenting symptomatology of HE and other causes of altered mental status must be excluded during the workup. HE is a well-known complication of transjugular intrahepatic portosystemic shunt (TIPS) placement. Even though newer stent designs help reduce the risk of HE with smaller diameter shunts, it is essential that patients are counseled regarding this potential risk prior to the procedure. Once a diagnosis of HE has been confirmed, the mainstay of therapy is lactulose and rifaximin. In cases where a patient has received a TIPS placement and continues to experience refractory HE despite medical therapy, it may be necessary to consider shunt reduction or closure.

Whole Model Path Planning-Guided Multi-Axis and Multi-Material Printing of High-Performance Intestinal Implantable Stent.

The problems of step effects, supporting material waste, and conflict between flexibility and toughness for 3D printed intestinal fistula stents are not yet resolved. Herein, the fabrication of a support-free segmental stent with two types of thermoplastic polyurethane (TPU) using a homemade multi-axis and multi-material conformal printer guided with advanced whole model path planning is demonstrated. One type of TPU segment is soft to increase elasticity, and the other is used to achieve toughness. Owing to advancements in stent design and printing, the obtained stents present three unprecedented properties compared to previous three-axis printed stents: i) Overcoming step effects; ii) Presenting comparable axial flexibility to a stent made of a single soft TPU 87A material, thus increasing the feasibility of implantation; and iii) Showing equivalent radial toughness to a stent made of a single hard TPU 95A material. Hence, the stent can resist the intestinal contractive force and maintain intestinal continuity and patency. Through implanting such stents to the rabbit intestinal fistula models, therapeutic mechanisms of reducing fistula output and improving nutritional states and intestinal flora abundance are revealed. Overall, this study develops a creative and versatile method to improve the poor quality and mechanical properties of medical stents.

Faster smooth muscle cell coverage in ultrathin-strut drug-eluting stent leads to earlier re-endothelialization.

Background: The ultrathin-strut drug-eluting stent (DES) has shown better clinical results than thin- or thick-strut DES. We investigated if re-endothelialization was different among three types of DES: ultrathin-strut abluminal polymer-coated sirolimus-eluting stent (SES), thin-strut circumferential polymer-coated everolimus-eluting stent (EES), and thick-strut polymer-free biolimus-eluting stent (BES) to gain insight into the effect of stent design on promoting vascular healing. Methods: After implanting three types of DES in the coronary arteries of minipigs, we performed optical coherence tomography (OCT) at weeks 2, 4, and 12 (n = 4, each). Afterward, we harvested the coronary arteries and performed immunofluorescence for endothelial cells (ECs), smooth muscle cells (SMCs), and nuclei. We obtained 3D stack images of the vessel wall and reconstructed the en face view of the inner lumen. We compared re-endothelialization and associated factors among the different types of stents at different time points. Results: SES showed significantly faster and denser re-endothelialization than EES and BES at weeks 2 and 12. Especially in week 2, SES elicited the fastest SMC coverage and greater neointimal cross-sectional area (CSA) compared to EES and BES. A strong correlation between re-endothelialization and SMC coverage was observed in week 2. However, the three stents did not show any difference at weeks 4 and 12 in SMC coverage and neointimal CSA. At weeks 2 and 4, SMC layer morphology showed a significant difference between stents. A sparse SMC layer was associated with denser re-endothelialization and was significantly higher in SES. Unlike the sparse SMC layer, the dense SMC layer did not promote re-endothelialization during the study period. Conclusion: Re-endothelialization after stent implantation was related to SMC coverage and SMC layer differentiation, which were faster in SES. Further investigation is needed to characterize the differences among the SMCs and explore methods for increasing the sparse SMC layer in order to improve stent design and enhance safety and efficacy.

Design and Experiment Research of a Novel Retrievable Peripheral Vascular Stent

Abstract Restenosis after stent implantation is a major limitation of revascularization technique. Retrieving the stent safely and smoothly after the vascular remodeling is completed shows important clinical value. In this paper, a novel retrievable peripheral vascular stent and its modified retrieval platform were developed and a finite element analysis (FEA) model was established to study the retrieval process of the stent. Meanwhile, the safety and feasibility of the retrievable stent were assessed through in vivo experiments. The maximum strain of the stent is 6.87% during the whole retrieval process, which is less than the ultimate elastic strain of nitinol alloy. The simulation results indicate that the stent is not damaged during the whole retrieval process. Finally, the stents were implanted into Bama miniature pigs to assess the retrieval process, and the results suggest that the stents can be retrieved successfully within 30 min after implantation, and minor local mechanical injury can be found in the intimal layer of the blood vessel due to the deployment and retrieval of the stent. Studies presented in this work illustrate the feasibility of a novel retrievable peripheral vascular stent, providing an additional avenue to reduce the risk of restenosis.

What Is the Optimal Duration of Antiplatelet Therapy for Patients with Coronary Heart Disease?

Optimal duration of antiplatelet therapy continues to attract extensive debates and has been progressively adjusted in the setting of advancements in stent design and assessment of patient clinical characteristics. Given the ever-changing landscape of antiplatelet therapy and the multitude of clinical trials that have examined this duration, there are varying scenarios for optimal duration based on patient presentation and risk profile. This review highlights the current concepts and recommendations regarding duration of antiplatelet therapy in coronary heart disease. In particular, we review the current data on the use of dual antiplatelet therapy in the different clinical scenarios. Relatively longer dual antiplatelet therapy is perhaps limited to patients with higher risk for cardiovascular events and/or high-risk lesions and shorter durations of dual antiplatelet therapy have been shown to reduce bleeding complications at the same time as stabilization of ischemic endpoints. More recent trials have demonstrated the safety of shorter durations of dual antiplatelet therapy in appropriate patients with coronary heart disease.

Computer Simulation of the Coupling Between Recirculation Flows and Drug Release from a Coronary Drug-Eluting Stent

This study examines the effect of recirculation zones and flow pulsatility on the transfer of the active ingredient from drug-eluting stents to the arterial wall, which can be hindered by recirculation zones located upstream and downstream of stent struts, leading to restenosis and thrombosis. Numerical simulations were conducted using a left coronary artery model with steady or pulsatile flows, and mass transfer analysis was performed on a single-stent strut with a square cross section. The findings offer valuable insights into optimizing the geometric design of drug-eluting stents by controlling the size and dynamics of induced recirculation cells, thereby enhancing the efficacy of stent treatments.

A novel ex vivo tracheobronchomalacia model for airway stent testing and in vivo model refinement

ObjectivesWe sought to develop an ex vivo trachea model capable of producing mild, moderate, and severe tracheobronchomalacia for optimizing airway stent design. We also aimed to determine the amount of cartilage resection required for achieving different tracheobronchomalacia grades that can be used in animal models. MethodsWe developed an ex vivo trachea test system that enabled video-based measurement of internal cross-sectional area as intratracheal pressure was cyclically varied for peak negative pressures of 20 to 80 cm H2O. Fresh ovine tracheas were induced with tracheobronchomalacia by single mid-anterior incision (n = 4), mid-anterior circumferential cartilage resection of 25% (n = 4), and 50% per cartilage ring (n = 4) along an approximately 3-cm length. Intact tracheas (n = 4) were used as control. All experimental tracheas were mounted and experimentally evaluated. In addition, helical stents of 2 different pitches (6 mm and 12 mm) and wire diameters (0.52 mm and 0.6 mm) were tested in tracheas with 25% (n = 3) and 50% (n = 3) circumferentially resected cartilage rings. The percentage collapse in tracheal cross-sectional area was calculated from the recorded video contours for each experiment. ResultsEx vivo tracheas compromised by single incision and 25% and 50% circumferential cartilage resection produce tracheal collapse corresponding to clinical grades of mild, moderate, and severe tracheobronchomalacia, respectively. A single anterior cartilage incision produces saber-sheath type tracheobronchomalacia, whereas 25% and 50% circumferential cartilage resection produce circumferential tracheobronchomalacia. Stent testing enabled the selection of stent design parameters such that airway collapse associated with moderate and severe tracheobronchomalacia could be reduced to conform to, but not exceed, that of intact tracheas (12-mm pitch, 0.6-mm wire diameter). ConclusionsThe ex vivo trachea model is a robust platform that enables systematic study and treatment of different grades and morphologies of airway collapse and tracheobronchomalacia. It is a novel tool for optimization of stent design before advancing to in vivo animal models.

Mechanics-guided design of inflatable heterogeneous shape memory polymer vascular stents

Vascular stent implantation is an effective method for the treatment of artery stenosis, and shape memory polymer (SMP) stents have become a promising stent type because of their good biodegradability and self-expandable capacity. However, due to the limited driving force obtained by the material's spontaneous recovery deformation, the current SMP stents suffer from low actuation speed and low actuation force during deployment. Here, we present a new design concept of SMP stents by utilizing two well-arranged heterogeneous SMPs in the stent structure domain and replacing the solid section with a hollow one. The resulting stents can therefore be inflated to expand and realize high-force actuations through extrinsically controlled pressure. A theoretical model that incorporates key design parameters including geometrical parameters and material distribution parameters is developed and validated by the finite element analysis to understand the fundamental mechanics of the stents during deployment. Design guidelines based on the model are further established to guide the design of the stents with desired performance. With support from the new design concept and associated theoretical foundation, the stents proposed here are expected to find wide applications in the biomedical field.