Stent Recoil Research Articles

TCT-488 Factors Associated With Chronic Stent Recoil and Its Impact on Revascularization: A Serial Optical Coherence Tomography Study

TCT-488 Factors Associated With Chronic Stent Recoil and Its Impact on Revascularization: A Serial Optical Coherence Tomography Study

Long-Term Results of Stenting in Patients with Hemodynamically Significant Lesions of the Left Main Coronary Artery

The aim. To study the long-term results of stenting in patients with coronary artery disease with hemodynamically significant left main coronary artery (LMCA) stenoses.
 Materials and methods. The study included 67 patients (56 men, 11 women) with a mean age of 63 ± 2.1 years.
 Results. Among the 67 patients included in the study, 29 patients (43.3%) underwent percutaneous coronary inter-vention using a single-stent technique. These were patients with ostial LMCA lesions, lesions of the middle third of the LMCA and some patients with Medina 1.1.0; 1.0.1; 1.0.0; 0.1.0; 0.0.1 lesions of the distal part of the LMCA. The median follow-up was 2 years. Using a questionnaire, we managed to establish contact with 25 patients (86.2%). Among these, 1 patient (3.4%) died of non-cardiac causes and 7 patients (24.1%) had a recurrence of angina within 2 years. The causes of angina recurrence in 2 cases (6.9%) were restenosis in the stent with transition to the mouth of the side branch, which required repeated stenting of the LMCA with transition to the left circumflex artery. In 5 patients (17.2%), angina recur-rence was associated with progression of coronary atherosclerosis of another localization.
 Among 67 patients with LMCA stenting, the two-stent technique was used in 38 patients (56.7%). These were pa-tients with Medina 1.1.0; 1.0.1; 1.0.0; 0.1.0; 0.0.1 lesions of the distal part of the LMCA. The median follow-up was 2 years. Using a questionnaire, we managed to contact 35 patients (92.1%). Among these, 4 patients (10.5%) died, but only one of them due to cardiac causes (2.6%), and 3 patients (7.9%) had recurrent angina within 2 years, two of whom underwent stenting by the T and protrusion (TAP) technique and one by culotte. The first two patients underwent angioplasty of restenosis in stents using balloons with a therapeutic coating. In the last patient, stent recoil in the left circumflex artery mouth was observed due to severe calcification, so this patient underwent re-implantation of the stent system in the recoil zone.
 Conclusions. The problem of choosing a method of revascularization for patients with hemodynamically significant LMCA lesions remains controversial to this day, despite the wide range of evidence. Doctors should jointly decide on the choice of treatment methodology solely in the interests of the patient, taking into account all the factors that may affect the patient’s quality of life in the long term.

Improvement of Work-Hardening Behavior of Co-Cr-W-Ni Alloy by Adding Mn/Fe for Balloon-Expandable Stents

The Co-20Cr-15W-10Ni (CCWN, mass%) alloy, registered as American society of testing and materials (ASTM) F90, has been widely used as a balloon-expandable stent because of its excellent balance between its mechanical properties and corrosion resistance. To realize a less invasive stent placement, the stent diameter must be reduced, which implies that the stent strut thickness must be reduced. As such, the CCWN alloy must be high in strength and ductility while maintaining a low yield stress to facilitate the expansion and suppression of stent recoil. In this study, we focus on the effects of the adding Mn/Fe on the microstructure, mechanical properties, and corrosive properties of CCWN alloys. A 6 mass% Mn-added CCWN alloy with a grain size of approximately 20 μm prepared in this study exhibits excellent balance between tensile strength and ductility. In addition, it exhibits a lower yield stress while maintaining a high tensile strength compared with the ASTM F90 alloy. Meanwhile, a 6 mass% Fe-added CCWN alloy exhibits a higher ductility compared with the ASTM F90 alloy. The addition of Mn or Fe to the CCWN alloy increases the stacking fault energy of the alloy and suppresses strain-induced martensitic transformation during plastic deformation, thus improving the ductility of the alloy. Results of polarization tests show that the 6 mass% Mn-or Fe-added CCWN alloys exhibit the same corrosion current density as the ASTM F90 alloy. Mn-added Co-Cr-W-Ni alloys are suitable for use in balloon-expandable stents.

Revolutionary auxetic intravascular medical stents for angioplasty applications

Due to the significant mortality rate associated with atherosclerosis-induced cardiovascular disease, the utilization of advanced intravascular stents with superior mechanical performance is imperative for the restoration of obstructed arteries. This study proposes novel auxetic medical stents that aim to enhance critical parameters of biomedical stents. This includes load-bearing capacity, expanded opening percentage, and reduced recoil percentage. On this matter, the missing rib auxetic unit cell has been considered and geometrically modified to achieve these objectives. Two-dimensional (2D) metamaterials were fabricated through additive manufacturing technique and subjected to experimental testing. Then, finite element analysis (FEA) was employed to gain comprehensive insights into the mechanical behaviour of the proposed medical stents. Remarkably, an excellent correlation was observed between the FEA and experimental results, validating the high precision of the analysis. The findings reveal that the stents classified as “E-category” exhibit the highest final opening percentage while concurrently demonstrating the lowest recoil percentage. The base stent exhibited a relatively high recoil percentage of 15.56%, indicating a significant amount of recoil or spring-back after deformation. In contrast, the modified “E-category” stent displayed a substantially lower recoil percentage of 1.62%. This notable reduction in recoil percentage indicates that the modifications made to the rib-unit cells had a significant and beneficial effect on the stent's recoil behaviour and minimizing potential damage to arterial tissue during stent deployment (angioplasty) and balloon pressure. The modified design likely enhances the stent's ability to maintain its shape and resist recoil, making it more effective and reliable in its intended application. Additionally, more aspects of biomedical stents such as foreshortening, and dog-boning of the modified missing rib stents were meticulously examined through FEA.

Proof of Concept: A New Solution for Low-Profile Transcatheter Implantation of Optimus-L Stents in Small Children

BackgroundThere is no stent designed or approved for use in infants. We sought to obtain in vitro and in vivo data on a new concept conceived to implant Optimus-L stents at infant vessel diameters and offer a potential long term stent solution. MethodsNineteen Optimus-L stents were mounted on 8 types of angioplasty balloons with diameters 6, 8, and 10 mm with the use of an injection-moulded hand crimper. We evaluated balloon-stent unit (BSU) stability before insertion and advancement through short Terumo introducers with incremental French size and possibility of side-arm contrast injections. Three types of long sheaths were tested. Stents were inflated to balloon nominal diameters and re-expanded to 18 and 23 mm. Stent recoil, foreshortening, and fracture were evaluated. In vivo implantations were performed afterward. ResultsIn vitro: Medtronic Evercross balloons and modified Terumo Destination sheaths were the best combination: BSUs were inserted in 6 F sheaths with possible injections (for 6 and 8 mm balloons), and 7 F sheaths without injections (for the 10 mm balloon). Retrieving BSUs inside the sheath required 1 additional F-size. Boston Scientific Sterling and Balton Lovix balloons, as well as APT Braidin L guiding sheaths showed unsatisfactory performance. Dilation up to 23 mm was possible, and stent shortening was < 24% at 18 mm and < 37% at 23 mm. Recoil was limited, and no stent fractured. In vivo: Optimus-L stents were used to treat 2 infants with aortic coarctation and 2 children with pulmonary artery stenosis with the use of 8 mm balloons and low-profile access. ConclusionsOptimus-L stents can be implanted safely in small patients with a low-profile approach. These stents have the potential to achieve adult size while maintaining structural integrity.

Stent expansion in calcified coronary chronic total occlusions: The impact of different stent platforms.

To evaluate the stent expansion of the durable-polymer Zotarolimus-eluting stent (dp-ZES), the durable-polymer Everolimus-eluting stent (dp-EES), and the bioabsorbable-polymer Sirolimus-eluting stent (bp-SES) in calcified coronary chronic total occlusions (CTO). The newer generation stents with ultrathin struts might raise concerns regarding reduced radial strength and higher stent recoil (SR) when implanted in calcified CTOs. Between January 2017 and June 2021 consecutive patients with CTO undergoing percutaneous coronary intervention with dp-ZES, dp-EES, or bp-SES were evaluated. The analysis was performed in calcific and in noncalcific CTOs. Quantitative coronary angiography analysis was used to assess diameter stenosis (DS), absolute and relative SR, absolute and relative focal SR, absolute and relative balloon deficit (BD), and absolute and relative focal BD. The primary endpoint was DS. A total of 213 CTOs were evaluated, 115 calcific CTOs (dp-ZES:25, dp-EES:29, bp-SES:61) and 98 non-calcific CTOs (dp-ZES:41, dp-EES:11, bp-SES:46).In calcific CTOs, residual DS was lower in dp-ZES than in dp-EES and bp-SES (-1.00% [-6.50-6.50] vs. 13.00% [7.0-19.00] vs. 15.00% [5.00-20.00]; p < 0.001). Dp-ZES was also an independent predictor of residual DS ≤ 10% (OR 11.34, 95% CI 2.6-49.43, p = 0.001). Absolute and relative focal SR and absolute and relative SR were similar between dp-ZES, dp-EES, and bp-SES (p = 0.913, p = 0.890, p = 0.518, p = 0.426, respectively). In noncalcified CTOs, the residual DS was similar in the three groups (p = 0.340). High relative focal SR was less frequent in dp-ZES than in dp-EES and in bp-SES (19.5% vs. 54.5% vs. 37.0%; p < 0.048). The three stent platforms demonstrated an overall low residual DS when implanted in CTOs. However, dp-ZES was associated with the lowest residual DS and identified as independent predictor of residual DS ≤ 10% in patients with calcific CTOs. Dp-ZES was associated with a lower incidence of high relative focal stent recoil, in noncalcific CTOs. Balloon deficit might be considerate as a surrogate for stent expansion in calcified CTOs.

Use of Zephyr stent in congenital heart diseases: A single-center study.

Large vessel stenosis is currently successfully treated with percutaneous stent implantation. Zephyr stent is a cobalt-chromium peripheral stent specifically designed for large-vessel stenting. Its specific "S-" and "C-" shaped flexible polylinks prevent stent foreshortening and recoil. We report our experience of using Zephyr among the pediatric population and their medium-term outcome. The study included a total of 19 patients treated with 21 Zephyr stents. The indications for stenting included coarctation of the aorta (four patients), stenosed pulmonary artery (eight patients), stenosed right ventricular outflow tract (five patients) or conduit (one patient), and percutaneous Fontan (one patient). All the procedures were successful. None of the patients showed any stent-related complications. Stent fractures, foreshortening, or recoil were not seen during follow-up. Our medium-term (1-20 months) follow-up showed a favorable outcome. One patient developed restenosis. Zephyr stent is a good therapeutic option for large-vessel stenting. However, it needs large-scale studies for further confirmation.

A New Approach to the Perceval Sutureless Aortic Valve

Aortic valve replacement surgery has changed in the past years. Perceval sutureless aortic valve (PV) is one of the responsible valves for those changes. However, oversizing the PV has been reported to be an issue. After a case of PV stent recoil at this institution, a new implantation technique was developed.

Novel hybrid 3D-printed auxetic vascular stent based on re-entrant and meta-trichiral unit cells: Finite element simulation with experimental verifications

In this study, a novel re-entrant meta-trichiral auxetic (RMCA) vascular stent with improved mechanical properties was designed by combining three auxetic unit cells: re-entrant, trichiral, and anti-trichiral. The in-plane tensile behavior of RMCA structure was investigated through finite element analysis and experimental tests were performed to verify the finite element analysis (FEA) results. 3D printing was employed to fabricate the samples. The effect of various geometric parameters on the in-plane behavior of RMCA structure, including the stress-strain curve and Poisson’s ratio, were studied using FE analysis. The highest value of negative Poisson's ratio obtained for RMCA structure was equal to − 4.91, which is a stunning value among auxetic structures. After that the vascular stent was proposed using the most appropriate structure determined by the parametric investigation. Finite element analysis (FEA) was conducted to evaluate the behavior of the stent during the deployment process (angioplasty), and interaction between the vascular stent, artery, and plaque. The dogboning, foreshortening, and recoil of the vascular stent were evaluated using the FEA results. Also, bending flexibility of the vascular stent was investigated based on FEA and three-point bending tests.

Unrecoverable stent deformation in the left main: Crush it or remove it?

Serial ostial and distal left main lesions continue to be one of the most difficult tasks for the interventional cardiologist, with many potential complications occurring. We present such a high-risk percutaneous coronary intervention where immediate stent explantation was deemed necessary because the metal deformation and high radial strength of the particular stent platform would prevent an acceptable procedural result if it had been crushed to the vessel wall. The aim of this paper was to discuss left main stent deformation, debate the risks and benefits of stent explantation and finally test in-vitro our theory on "insufficient" crush with stents with high radial strength and compare it with conventional stents. Bench-testing supports our ad-hoc explantation decision showing stent underexpansion, recoil, and malapposition, obtaining an inadequate minimal stent area.

Clinical Case of Unprotected Left Main Percutaneous Coronary Intervention in Elderly Patient With Porcelain Aorta

Coronary artery bypass grafting (CABG) has long been considered the gold standard in the treatment of patients with lesions of the left main (LM) coronary artery. Elderly patients are one of the most difficult categories of patients with LM lesions due to severe coronary artery calcification. Thanks to constant progress in the field of engineering and technology, it has become possible to perform percutaneous coronary interventions (PCI) for patients with unprotected stenosis of the LM. Drug-eluting stents and the development of pharmacotherapy have improved the results of PCI in these lesions. Comparative studies of the efficacy and safety of PCI and CABG have shown similar results in terms of the need for revascularization. Patients with severe calcification of the coronary arteries mostly belong to the older age group and hold large part in this cohort. Technological advances enabled to treat patients with complex coronary anatomy and LM lesions not only through CABG, but also through PCI. Comparative studies show that the efficacy and safety of PCI and CABG have similar results in terms of the need in revascularization.&#x0D; The aim. To highlight the importance of discussion of each clinical case by the heart team and comprehensive approach with the use of modern equipment.&#x0D; Stage 1. A 80-year-old woman with type 2 diabetes mellitus was delivered by an ambulance team to the National Amosov Institute of Cardiovascular Surgery with severe pain; the patient was diagnosed with non-ST-elevation myocardial infarction (NSTEMI). Electrocardiography revealed ST-segment depression in leads V1-V5. After performing echocardiographic examination, valvular pathology and segmental contraction defects were not detected, EF 52%.&#x0D; Urgent coronary angiography revealed significant calcification of the ascending aorta (porcelain aorta) and coronary arteries. Coronary artery lesions: 90% unstable LM stenosis, significant calcified stenosis of the circumflex artery (CA), middle left anterior descending artery (mid-LAD), and chronic coronary occlusion of the right coronary artery, besides, 5 episodes of ventricular tachycardia were recorded. Despite the high SYNTAX Score I and SYNTAX Score II, due to the clinical picture and heart rhythm disorders, the heart team decided to perform emergency PCI. Bare-metal stent for LM – mid-LAD was implanted and angioplasty of mid-LAD was performed. Rough calcification of LM caused stent recoil; postdilatation of LM stent by high pressure balloon (p = 25 atm) was performed. The operation ended with a good angiographic result. The woman was discharged in a stable condition to plan further intervention in 1 month.&#x0D; Stage 2. A 81-year-old woman with complaints of severe chest pain was re-hospitalized with NSTEMI to the National Amosov Institute of Cardiovascular Surgery 3 months after the primary PCI. Echocardiography revealed EF 53%; valvular pathology and segmental contraction defects were not detected. Urgent coronary angiography revealed 90% of LM stenosis (stent recoil – loss of radial rigidity). Gradual angioplasty of LM stenosis and CA stenosis were performed.&#x0D; Stage 3. For reinforcing the radial rigidity in LM, LM – CA drug-eluting stent was implanted. Angioplasty of LM and CA using kissing balloon technique was performed. Final proximal optimization of LM showed good angiographic result.

Intravascular lithotripsy for severely calcified carotid artery stenosis - A new frontier in carotid artery stenting?

Carotid stenosis due to severely calcified plaque can pose a significant therapeutic challenge. Extremely calcified scars/stenosis plaques can be challenging from an endovascular treatment perspective as severely calcified lesions are prone to technical failure, stent re-coil and restenosis. Intravascular lithotripsy, approved for treatment of severely calcified coronary lesions, can be used for breaking up the calcium build up in the intimal and medial layers of the vessel wall prior to stenting. This was designated as a breakthrough device innovation by the Food and Drug Administration. This new technique addresses the challenge of the disease without compromising patient safety during the procedure. We here report procedural set-up, execution and early patient follow up from our first use of this emerging technology in a neurointerventional practice setting.

690 Acute post-implantation enlargement of transcatheter self-expandable valve: insights from a single-centre prospective registry

Abstract Aims Transcatheter implantation of a balloon-expandable aortic valve is associated with an acute stent recoil . Conversely, the acute effects of nitinol-based stent frame- self expandable valve on post-deployment dimensions have not been reported. Accordingly, the aim of this study was to assess the occurrence and degree of acute prosthetic dimension changes after Evolute R valve implantation. Methods A total of 58 consecutive patients undergoing transcatheter aortic valve intervention (TAVI) with a widely used nitinol based self-expandable device (Evolute R, Medtronic, Minneapolis, USA) were included in this study. We measured valve diameters at three different sections: a) distal (aortic) level, b) central (annulus) level, and c) proximal (ventricular) level. Valve expansion was calculated as the difference between the diameters calculated immediately after valve deployment (A) and at the end of the procedure (B). The absolute and relative acute stent recoil were defined as B-A and (B-A)/B*100, respectively. A linear regression model was performed to test the association between the degree of valve extension, with baseline, as well as procedural characteristics. Results Final stent diameters were significantly higher compared to those achieved immediately after valve implantation in proximal (20.87±3.20 mm versus 20.37±3.27 mm, P &amp;lt;0.001), central (19.58±1.63 mm versus 19.12±1.75 mm, P &amp;lt;0.001) as well as distal (26.99±1.53 mm versus 26.41±1.57 mm, P &amp;lt;0.001) segments. The mean absolute and relative enlargement of the valve was respectively 0.50±0.51 mm and 2.48±2.57% in the proximal, 0.46±0.57 mm and 2.39±2.96% in the central and 0.58±0.59 mm and 2.14±2.14% in the distal segment. Among baseline and procedural characteristics assessed in the logistic regression model no association was observed between pre-dilation and valve expansion across all the segments (proximal: r2=0.004, P=0.885, central: r2=0.004, P=0.637, and distal r2=0.05, P=0.10). Of interest, post dilation affected only the expansion of the central segment (r2=0.241, P&amp;lt;0.001), while no association was observed for the proximal (r2=0.059, P=0.065) and distal (r2=0.0002, P=0.916) parts. The expansion of the proximal segment was associated with higher maximum/minimum diameter ratio measured by CT (r2=0.08, P=0.045), while no association was observed for the central (r2= 0.020; P=0.992) and distal (r2=1.111, P=0.683) segments. Conclusions This is the first study that documented a significant degree of post-deployment recoil of the Evolute R self-expandable valve, that was consistent across all the segments. The stent-valve expansion of the proximal segment was associated with a greater annulus dissymmetry reported by the maximum and minimum diameter ratio assessed by CT scan. However, further studies are required to assess the short and long-term time-course of self-expandable valve enlargement and the clinical relevance of this finding.

Subjective approach to optimal cross-sectional design of biodegradable magnesium alloy stent undergoing heterogeneous corrosion

Existing biodegradable Magnesium Alloy Stents (MAS) have several drawbacks, such as high restenosis, hasty degradation, and bulky cross-section, that limit their widespread application in a current clinical practice. To find the optimum stent with the smallest possible cross-section and adequate scaffolding ability, a 3D finite element model of 25 MAS stents of different cross-sectional dimensions were analysed while localized corrosion was underway. For the stent geometric design, a generic sine-wave ring of biodegradable magnesium alloy (AZ31) was selected. Previous studies have shown that the long-term performance of MAS was characterized by two key features: Stent Recoil Percent (SRP) and Stent Radial Stiffness (SRS). In this research, the variation with time of these two features during the corrosion phase was monitored for the 25 stents. To find the optimum profile design of the stent subjectively (without using optimization codes and with much less computational costs), radial recoil was limited to 27 % (corresponding to about 10 % probability of in-stent diameter stenosis after an almost complete degradation) and the stent with the highest radial stiffness was selected.The comparison of the recoil performance of 25 stents during the heterogeneous corrosion phase showed that four stents would satisfy the recoil criterion and among these four, the one having a width of 0.161 mm and a thickness of 0.110 mm, showed a 24 % – 49 % higher radial stiffness at the end of the corrosion phase. Accordingly, this stent, which also showed a 23.28 % mass loss, was selected as the optimum choice and it has a thinner cross-sectional profile than commercially available MAS, which leads to a greater deliverability and lower rates of restenosis.

Point-of-care 3D printing: a low-cost approach to teaching carotid artery stenting

BackgroundCarotid Artery Stenting (CAS) is increasingly being used in selected patients as a minimal invasive approach to carotid endarterectomy. Despite the long standing tradition of endovascular treatments, visual feedback during stent-deployment is impossible to obtain as deployment is performed under fluoroscopic imaging. Furthermore, the concept of stent-placement is often still unclear to patients. 3D Printing allows to replicate patient-specific anatomies and deploy stents inside them to simulate procedures. As such these models are being used for endovascular training as well as patient education.PurposeTo our knowledge, this study reports the first use of a low-cost patient-specific 3D printed model for teaching CAS deployment under direct visualization, without fluoroscopy.MethodologyA CT-angiogram was segmented and converted to STL format using Mimics inPrint™ software. The carotid arteries were bilaterally truncated to fit the whole model on a Formlabs 2 printer without omitting the internal vessel diameter. Next, this model was offset using a 1 mm margin. A ridge was modelled on the original vessel anatomy which was subsequently subtracted from the offset model in order to obtain a deroofed 3D model. All vessels were truncated to facilitate post-processing, flow and guide wire placement.ResultsCarotid artery stents were successfully deployed inside the vessel. The deroofing allows for clear visualization of the bottlenecks and characteristics of CAS deployment and positioning, including stent foreshortening, tapering and recoil. This low-cost 3D model provides visual insights in stent deployment and positioning, and can allow for patient-specific procedure planning.ConclusionsThe presented approach demonstrates the use of low-cost 3D Printed CAS models in teaching complex stent behavior as observed during deployment. Two main findings are illustrated. On one hand, the feasibility of low-cost in-hospital model production is shown. On the other hand, the teaching of CAS deployment bottlenecks at the carotid level without the need for fluoroscopic guidance, is illustrated. The observed stent characteristics as shown during deployment are difficult to assess in radiologic models. Furthermore, printing patient-specific 3D models preoperatively could possibly assist in accurate patient selection, preoperative planning, case-specific training and patient education.

Development of Low-Yield Stress Co\u2013Cr\u2013W\u2013Ni Alloy by Adding 6 Mass Pct Mn for Balloon-Expandable Stents

This is the first report presenting the development of a Co–Cr–W–Ni–Mn alloy by adding 6 mass pct Mn to ASTM F90 Co–20Cr–15W–10Ni (CCWN, mass pct) alloy for use as balloon-expandable stents with an excellent balance of mechanical properties and corrosion resistance. The effects of Mn addition on the microstructures as well as the mechanical and corrosion properties were investigated after hot forging, solution treatment, swaging, and static recrystallization. The Mn-added alloy with a grain size of ~ 20 µm (recrystallization condition: 1523 K, 150 seconds) exhibited an ultimate tensile strength of 1131 MPa, 0.2 pct proof stress of 535 MPa, and plastic elongation of 66 pct. Additionally, it exhibited higher ductility and lower yield stress while maintaining high strength compared to the ASTM F90 CCWN alloy. The formation of intersecting stacking faults was suppressed by increasing the stacking fault energy (SFE) with Mn addition, resulting in a lower yield stress. The low-yield stress is effective in suppressing stent recoil. In addition, strain-induced martensitic transformation during plastic deformation was suppressed by increasing the SFE, thereby improving the ductility. The Mn-added alloys also exhibited good corrosion resistance, similar to the ASTM F90 CCWN alloy. Mn-added Co–Cr–W–Ni alloys are suitable for use as balloon-expandable stents.

Design and Shape Optimization of a Biodegradable Polymeric Stent for Curved Arteries Using FEM

Stent treatment has revealed safe and efficient outcomes for straight arteries, while it is still challenging for curved coronary arteries. On the one hand, a stent should be flexible enough to take the artery’s curvature with the least stress to the artery wall. On the other hand, it has to be strong enough to prevent any artery diameter reduction after the implant. In this work, the genetic algorithm multi-objective optimization method is exploited to provide a Pareto set and to design a curvature stent. The design has been performed based on the appropriate flexibility and radial strength design, depending on the characteristics of a particular case study. In the optimization procedure, flexibility and radial strength have been evaluated based on ASTM standard mechanical tests. These tests have been parametrically simulated using the finite element method. The strut curvature is formed by the spline curvature, whose middle point coordinates are two of the optimization variables. The other optimization variable is the thickness of the stent. Based on the Pareto set achieved from the optimization, five different stent designs have been proposed. In these designs, the middle part of the stent is stiffer (in the plaque aggregated) and benefits more radial strength rather than flexibility. At the stent’s extremes, where more deformation takes place, flexibility is weighted more than radial strength. These five design sets differ in their objective weight ratios. At the end of this research, their implementation in a curved vessel is simulated in ABAQUS/CAE, and von Mises stress distribution, maximum von Mises stress, and stent recoil after imposing the stent have been analyzed. The obtained Pareto front can also be a useful guide for physicians to design and manufacture customized stents for each patient.

Elastic stent recoil in coronary total occlusions: Comparison of durable-polymer zotarolimus eluting stent and ultrathin strut bioabsorbable-polymer sirolimus eluting stent.

ObjectivesTo compare stent recoil (SR) of the thin‐strut durable‐polymer Zotarolimus‐eluting stent (dp‐ZES) and the ultrathin‐strut bioabsorbable‐polymer Sirolimus‐eluting stent (bp‐SES) in chronic total occlusions (CTOs) and to investigate the predictors of high SR in CTOs.BackgroundNewer ultrathin drug eluting stent might be associated with lower radial force and higher elastic recoil due to the thinner strut design, possibly impacting on the rate of in‐stent restenosis and thrombosis.MethodsBetween January 2017 and November 2019, consecutive patients with CTOs undergoing percutaneous coronary intervention were evaluated. Only patients treated with dp‐ZES or bp‐SES were included and stratified accordingly. Quantitative coronary angiography analysis was used to assess absolute SR, relative SR, absolute focal SR, relative focal SR, high absolute, and high relative focal SR.ResultsA total of 128 lesions (67 treated with dp‐ZES and 61 with bp‐SES) in 123 patients were analyzed. Between bp‐SES and dp‐ZES no differences were found in absolute SR (p = .188), relative SR (p = .138), absolute focal SR (p = .069), and relative focal SR (p = .064). High absolute and high relative focal SR occurred more frequently in bp‐SES than in dp‐ZES (p = .004 and p = .015). Bp‐SES was a predictor of high absolute focal SR (Odds ratio [OR] 3.29, 95% confidence interval [CI] 1.50–7.22, p = .003]. High‐pressure postdilation and bp‐SES were predictors of high relative focal SR (OR 2.22, 95% CI 1.01–4.86, p = .047; OR 2.74, 95% CI 1.24–6.02, p = .012, respectively).ConclusionsBoth stents showed an overall low SR. However, ultra‐thin strut bp‐SES was a predictor of high absolute and high relative focal SR.

Midterm results after covered stenting of the superior mesenteric artery

ObjectiveDespite the continuing controversy of covered stents (CS) vs bare metal stents, the use of CS in mesenteric occlusive disease (MOD) has been recommended by expert centers. The aim of this study was to report midterm results with CS of the superior mesenteric artery. MethodsBetween January 2014 and October 2019, patients with MOD with a severe atheromatous stenosis or occlusion of the superior mesenteric artery treated by mesenteric CS were included. Clinical presentation included both acute mesenteric ischemia (AMI), chronic mesenteric ischemia, and asymptomatic patients planned for major surgery. Demographics, procedure details, and follow-up data were prospectively collected and retrospectively reviewed. Study end points included primary patency, primary assisted patency, and secondary patency. ResultsDuring the study period, 86 patients (mean age, 70 ± 9 years; 57% males) were included. Clinical presentation was AMI (n = 42 [49%]), chronic mesenteric ischemia (n = 31 [36%]), and asymptomatic (n = 13 [15%]). The technical success rate was 97%. A total of 96 stents were implanted, including 86 proximal CS (Advanta V12, n = 73; Lifestream, n = 13). The mean length and mean diameter of the CS were 31.5 ± 6.3 mm and 6.9 ± 0.5 mm, respectively. Additional distal bare metal stents were used in 10 patients (12%) to overcome a kinking (n = 9) or a dissection (n = 1) downstream of the CS. All postoperative deaths occurred in patients with AMI (n = 11, 13%). During a median follow-up of 15.6 months (95% confidence interval [CI], 15.6 ± 3.6 months), 12 patients (14%) underwent reinterventions for either stent misplacement (n = 3), stent recoil (n = 3), stent thrombosis (n = 2), de novo stenosis at the distal edge of the CS (n = 2), or gastric ischemia (n = 1). At 1 year, overall the primary patency, primary assisted patency, and secondary patency rates were 83% (95% CI, 83% ± 9%), 99% (95% CI, 99% ± 3%), and 99% (95% CI, 99% ± 3%), respectively. At 2 years, the overall primary patency, primary assisted patency, and secondary patency rates were 76% (95% CI, 76% ± 13%), 95% (95% CI, 95% ± 8%) and 95% (95% CI, 95% ± 8%), respectively. ConclusionsMesenteric CS provide very satisfactory midterm results in patients with MOD, with an excellent primary assisted patency rate at 2 years, at the price of a significant reintervention rate.

Clinical Outcomes after Additional Dynamic Renal® Stent Implantation for Stent Recoil in Ostial Coronary Lesions.

Background: Interventional treatment of aorto-ostial coronary stenoses is limited by stent recoil and suboptimal angiographic results, leading to restenosis and frequent re-interventions. As a potential bail-out strategy for stent recoil, implantation of an additional stent to increase radial force has been reported. Thus, we sought to investigate clinical outcomes after additional implantation of a Dynamic Renal® stent (DRS), a non-coronary; bare-metal stent with very high radial force, in aorto-ostial coronary stenoses. Methods: Patients treated by implantation of DRSs for stent recoil in the ostial right coronary artery or the left main stem were identified from the hospital database. Baseline clinical and procedural characteristics were compared to patients who underwent re-intervention for in-stent-restenosis in similar segments by either implantation of conventional drug-eluting stents (DES) or paclitaxel-coated balloons (PCB). Clinical follow-ups were performed up to three years following re-intervention with the assessment of death, target lesion reintervention (TLR), and major adverse cardiac events (MACE) as a combination death, myocardial infarction and target vessel revascularization. Kaplan–Meier analyses were performed for event-free survival between the three groups. Results: Between 05/2013 and 07/2019, 28 patients underwent DRS implantation of aorto-ostial coronary lesions. In comparison with 49 patients with DES implantation and 29 patients undergoing PCB treatment, no relevant differences in baseline parameters were identified. Median follow-up was 714 days, with an available follow-up of >1 year after intervention in 82.1% of patients. In the entire study cohort at two years after re-intervention, the TLR rate was 16% (17 patients), the MACE rate 37% (39 patients), and all-cause mortality 9% (10 patients), with no significant differences between the three groups. Conclusions: DRS implantation for treating stent recoil of aorto-ostial coronary lesions resulted in a high rate of TLR, and was associated with similar risk for death and MACE compared to treatment of in-stent-restenosis with DES or PCB. Randomized, larger comparisons of contemporary DES in patients exclusively presenting with stent recoil are necessary to further define the efficacy and safety of this approach.