Hybrid Stent Graft Technique in Bridging Hostile Renal Arteries in Thoracoabdominal Branched Endografting.

OBJECTIVE: Patency of target arteries is crucial for fenestrated and branched endovascular aortic repair (F/B-EVAR) in thoracoabdominal aortic aneurysms (TAAAs). Occlusions more frequently occur in renal arteries (RAs) than in coeliac and superior mesenteric arteries, especially in patients with hostile anatomy treated by BEVAR. This study aimed to report RA outcomes using a hybrid bridging stent graft technique with distal self expandable (SE) combined with proximal balloon expandable (BE) stent graft during BEVAR with hostile RA anatomies. METHODS: Clinical data from consecutive patients treated for TAAA by F/B-EVAR in three aortic centres (two in the USA, one in Europe) from 2016 to 2022 were prospectively collected. Renal artery orientation was defined as hostile in case of upward (type B) or downward + upward (type D) orientation. Hostile RAs accommodated by BEVAR and combination of SE + BE stent grafts were retrospectively evaluated. Intra-operative RA related complications, technical success, and branch occlusions were assessed as early outcomes. Primary and secondary RA patency, freedom from RA related re-interventions, and freedom from RA instability were assessed during follow up. RESULTS: Of 584 TAAAs managed by F/B-EVAR, 83 patients (14.2%) had 125 hostile RAs (type B, 45.6%; type D, 54.4%) managed by BEVAR with hybrid SE + BE stent grafts. Intra-operative complications occurred in three RAs (2.4%), including two dissections and one disconnection, all successfully managed with additional stent. Technical success was achieved in all cases, with no RA occlusions at 30 days. The median follow up was 21 (interquartile range 4, 38) months. Estimated three year RA primary patency was 97 ± 2%. Re-interventions were performed in five RAs (4.0%), including two RA branch embolisations for bleeding, two catheter thrombectomies with stent relining (bilateral occlusion in one patient), and one revision of type Ic endoleak. Freedom from RA related re-interventions and RA instability was 95 ± 2% and 91 ± 3% at three years, respectively. Renal artery secondary patency was 99 ± 1% at three years. CONCLUSION: In hostile RA anatomies, a combination of distal SE and proximal BE stent grafts as bridging stenting in BEVAR is safe and effective, with low rates of occlusion, re-interventions, and branch instability at midterm follow up.

Effect of bridging stent graft selection for directional branches on target artery outcomes of fenestrated-branched endovascular aortic repair in the United States Aortic Research Consortium.

OBJECTIVE: The purpose of this study was to evaluate the effect of directional branches (DBs) bridging stent choice on target artery (TA) outcomes during fenestrated-branched endovascular repair of complex abdominal and thoracoabdominal aortic aneurysms. METHODS: Patients enrolled in nine prospective physician-sponsored investigational device exemption studies in the United States between 2005 and 2020 were analyzed. All patients who had at least one TA incorporated by DB using either self-expandable (SESGs), balloon-expandable (BESGs), or hybrid stent graft combinations (HSGs). Endpoints were TA patency and freedom from TA endoleak, instability, and reintervention. RESULTS: There were 800 patients with 2426 renal-mesenteric arteries incorporated by DBs. DB stent selection was SESGs in 1205 TAs (50%), BESGs in 1095 TAs (45%), and HSGs in 126 TAs (5%). SESGs were predominantly used in the first three quartiles of the study period, whereas BESGs comprised 75% of all stents between 2017 and 2020. The median follow-up was 15 months (interquartile range, 6-35 months). At 5 years, BESGs had significantly lower freedom from TA instability (78% ± 4% vs 88% ± 1% vs 96% ± 2%; log-rank P =.010), freedom from TA endoleaks (87% ± 3% vs 97% ± 1% vs 99% ± 1%; log-rank P < .001), and freedom from TA reintervention (83% ± 4% vs 95% ± 1% vs 99% ± 2%; log-rank P <.001) compared with SESGs or HSGs, respectively. For renal arteries, there was no difference in freedom from TA instability for BESGs, SESGs, or HSGs. However, freedom from TA endoleaks and reintervention were lower for renal arteries targeted by BESGs compared with DBs targeted by SESGs and HSGs (83% ± 6% vs 98% ± 1% vs 100%; log-rank P < .001; and 70% ± 10% vs 92% ± 1% vs 96% ± 4%; log-rank P = .022). For mesenteric arteries, DBs targeted by BESGs had lower freedom from TA instability, endoleak, and reintervention than SESGs or HSGs. In stent-specific analysis, iCAST BESGs had the lowest freedom from TA instability either for renal or mesenteric arteries, primarily due to higher rates of TA endoleaks. There was no difference in patency in any scenario. Independent predictors of TA instability were age (+1-year: hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.94-0.99), stent diameter (+1 mm: HR, 0.67; 95% CI, 0.57-0.80), and BESG (HR, 1.8; 95% CI, 1.1-2.9). CONCLUSIONS: DBs incorporated using BESGs had lower freedom from TA instability, TA endoleak, and TA reintervention compared with SESGs and HSGs. The patency of DBs was not affected by the type of stent construction. The observed performance disadvantage associated with BESGs appears to have largely been driven by iCAST usage.

Prophylactic relining for bridging stent compression after thoracoabdominal endovascular aneurysm repair: Myth or reality?

BACKGROUND/OBJECTIVE: Target vessels related complications are one of the most important 'Achille's heel' of complex thoracoabdominal endovascular procedures. The aim of this report is to describe a case of spontaneous bridging stent-graft (BSG) delayed expansion in a patient treated for type III mega-aortic syndrome, associated with aberrant right subclavian artery and independent origin of the two common carotid arteries. METHODS: The patient underwent different surgical procedures (ascending aorta replacement with carotid arteries debranching, bilateral carotid-subclavian bypass with subclavian origins embolization and TEVAR in zone 0, associated with a multibranched thoracoabdominal endograft deployment). Visceral vessels stenting was performed using balloon-expandable BSGs for celiac trunk, superior mesenteric artery and right renal artery, while for the left renal artery a 6 × 60 mm self-expandable BSG was deployed.The first follow-up (FU) by computed tomography angiography (CTA) showed a severe compression of the left renal artery BSG. Considering the challenging access to the directional branches (SAT's debranching and a tightly curve of the steerable sheath inside the branched main body), a conservative treatment was considered, performing a control CTA after 6-months. RESULTS: Six months later, the CTA demonstrated a spontaneous expansion of the BSG, with a two-fold increase in the minimum stent diameter, excluding the need for new reinterventions such as angioplasty or BSG relining. CONCLUSIONS: Directional branch compression is a frequent complication during BEVAR; however, in this case, it spontaneously resolved after 6 months, without the need for secondary adjunctive procedures. Further studies on predictor factors for BSG related adverse events and regarding spontaneous delayed BSGs' expansion mechanisms are needed.

Effect of branch length and tortuosity on the outcomes of branched endovascular repair of thoracoabdominal aneurysms using self-expandable bridging stent graft.

OBJECTIVE: We investigated the effect of the length and tortuosity of directional branches on the mid-term outcomes of branched endovascular aneurysm repair (BEVAR) for thoracoabdominal aortic aneurysms (TAAA). METHODS: We retrospectively reviewed single-center data of consecutive patients who had undergone BEVAR for TAAA from 2015 to 2019. Three-dimensional computed tomography angiogram reconstructions (Aquarius iNtuition software; TeraRecon, Durham, NC) of the first postoperative imaging studies were used to measure the branch total length (TL), branch vertical length (VL), and branch tortuosity index (TI). The branch TL was measured as the centerline distance between the branch proximal radiopaque marker and the distal edge of the bridging stent. The VL was measured as the centerline distance between the branch distal radiopaque marker and the origin of the target artery. The TI was measured in accordance with the Society for Vascular Surgery reporting standard. The primary end point was freedom from branch instability, defined as any branch-related death, occlusion, or rupture and any reintervention for stenosis, endoleak, or disconnection. Cox proportional hazards were used to identify predictors of branch instability. A penalized spline function was used to identify the relationship between branch instability and the branch TL and VL. RESULTS: Postimplantation analysis was conducted on 32 TAAAs (extent I-III, n = 18 [56%]; extent IV, n = 14 [44%]), with 123 arteries included through a directional branch. A covered self-expanding bridging stent was used in all cases. Intraoperative reinforcement with an additional bare metal stent was performed in 85 cases (69%). The overall freedom from branch instability at 3 years was 88% (95% confidence interval [CI], 81%-94%). Five cases of occlusion and eight cases of branch-related endoleak occurred. A concomitant endoleak and severe stenosis requiring intervention developed in three cases. The Cox model with splines showed that the minimal risk of branch instability was achieved with a branch TL of 60 to 100 mm (P = .002) and a branch VL of 25 to 50 mm (P = .038). A TI of >1.15 was a predictor of branch complications (hazard ratio [HR], 8.6; 95% CI, 2.4-31.4; P < .001). After multivariate analysis, aneurysm diameter (HR, 1.08; 95% CI, 0.03-1.15; P = .003), TI >1.15 (HR, 6.81; 95% CI, 2.17-27.33; P < .001), and TL <60 or >100 mm (P = .002) were significantly associated with branch instability. CONCLUSIONS: The branch length and TI seemed to play an important role in BEVAR outcomes. The lowest branch instability rates were obtained with a branch TL of 60 to 100 mm, and this should be considered during planning and implantation. A branch TI >1.15 might require a more strict monitoring to prevent mid- and long-term complications.

Outcomes of directional branches using self-expandable or balloon-expandable stent grafts during endovascular repair of thoracoabdominal aortic aneurysms.

OBJECTIVE: The objective of this study was to evaluate outcomes of directional branches using self-expandable stent grafts (SESGs) or balloon-expandable stent grafts (BESGs) during fenestrated-branched endovascular aneurysm repair of thoracoabdominal aortic aneurysms. METHODS: Patients treated by fenestrated-branched endovascular aneurysm repair were enrolled in a prospective study from 2014 to 2018. We included in the analysis patients who had target vessels incorporated by directional branches using either SESG (Fluency [Bard, Covington Ga] or Gore Viabahn [W. L. Gore & Associates, Flagstaff, Ariz]) or BESG (Gore VBX). Target artery instability (TAI) was defined by a composite of any stent stenosis, separation, or type IC or type IIIC endoleak requiring reintervention and stent occlusion, aneurysm rupture, or death due to target artery complication. End points included technical success, target artery patency, freedom from TAI, freedom from type IC or type IIIC endoleak, and freedom from target artery reintervention. RESULTS: There were 126 patients (61% male; mean age, 73 ± 8 years) included in the study. A total of 335 renal-mesenteric arteries were targeted by directional branches using SESGs in 62 patients and 176 arteries or BESGs in 54 patients and 159 arteries. Patients in both groups had similar thoracoabdominal aortic aneurysm classification and aneurysm and target artery diameter, but SESG patients had significantly (P < .05) shorter stent length (-7 mm) and larger stent diameter (+1 mm) and more often had adjunctive bare-metal stents (72% vs 15%). Technical success was achieved in 99% of patients, with one 30-day death (0.7%). Mean follow-up was significantly longer among patients treated by SESGs compared with BESGs (23 ± 12 months vs 8±8 months; P < .0001). TAI occurred in 27 directional branches (8%), including 11 type IC endoleaks (2 SESGs, 9 BESGs), 10 stenoses (3 SESGs, 7 BESGs), 4 occlusions (3 SESGs, 1 BESGs), 4 type IIIC endoleaks (2 SESGs, 2 BESGs), and 1 stent separation (SESG), resulting in 20 target artery reinterventions in 16 patients (5 SESGs and 11 BESGs). At 1 year, SESGs had higher primary patency (97% ± 2% vs 96% ± 2%; P = .004), freedom from TAI (96% ± 2% vs 88% ± 3%; P < .0001), freedom from type IC or type IIIC endoleaks (98% ± 1% vs 92% ± 3%; P = .0004), and freedom from target artery reinterventions (98% ± 1% vs 88% ± 4%; P < .0001) compared with BESGs. There was no difference in secondary patency for SESGs and BESGs (98% ± 1% vs 99% ± 1%; P = .75). Factors associated with TAI were large stent diameter (odds ratio, 0.6; P < .0001) and use of VBX stent graft (odds ratio, 6.5; P < .0001). CONCLUSIONS: Directional branches were associated with high technical success and low rates of stent occlusion, independent of stent type. However, primary patency, freedom from TAI, and freedom from type IC or type IIIC endoleaks was lower for BESGs compared with SESGs.

Sinus Superflex DS© early collapse in systemic arterial duct.

We implanted two sinus Superflex DS© stents in a systemic non-stenotic arterial duct of a newborn with hypoplastic left heart syndrome. Forty-eight hours later an important collapse of the stent was detected and treated with a balloon expandable stent. Sinus Superflex DS© has been specifically designed for systemic ducts. This complication generates doubts about its radial force in this scenario.

Self-expandable sirolimus-eluting stents compared to second-generation drug-eluting stents for the treatment of the left main: A propensity score analysis from the SPARTA and the FAILS-2 registries.

OBJECTIVES: To compare the effectiveness and safety of self-expandable, sirolimus-eluting Stentys stents (SES) and second-generation drug-eluting stents (DES-II) for the treatment of the unprotected left main (ULM). BACKGROUND: SES may provide a valuable option to treat distal ULM, particularly when significant caliber gaps with side branches are observed. METHODS: Patients from the multicenter SPARTA (clinicaltrials.gov: NCT02784405) and FAILS2 registries were included. Propensity-score with matching was performed to account for the lack of randomization. Primary end-point was the rate of major adverse cardiovascular events (MACE, a composite of all cause death, myocardial infarction, target lesion revascularization [TLR], unstable angina and definite stent thrombosis [ST]). Single components of MACE were the secondary end-points. RESULTS: Overall, 151 patients treated with SES and 1270 with DES-II were included; no differences in MACE rate at 250 days were observed (9.8% vs. 11.5%, P = 0.54). After propensity score with matching, 129 patients treated with SES and 258 with DES-II, of which about a third of female gender, were compared. After a follow-up of 250 days, MACE rate did not differ between the two groups (9.9% vs. 8.5%, P = 0.66), as well as the rate of ULM TLR (1.6% vs. 3.1%, P = 0.36) and definite ST (0.8% vs. 1.2%, P = 0.78). These results were consistent also when controlling for the treatment with provisional vs. 2-stents strategies for the ULM bifurcation. CONCLUSION: SES use for ULM treatment was associated with a similar MACE rate compared to DES-II at an intermediate-term follow-up. SES might represent a potential option in this setting.

Interaction of a self-expandable stent with the arterial wall in the presence of hypocellular and calcified plaques.

Self-expandable stents manufactured from nitinol alloys are commonly utilized alongside traditional balloon-expandable stents to provide scaffolding to stenosed arteries. However, a significant limitation hampering stent efficacy is restenosis, triggered by neointimal hyperplasia and resulting in the loss of gain in lumen size, post-intervention. In this study, a nonlinear finite element model was developed to simulate stent crimping and expansion and its interaction with the surrounding vessel in the presence of a plaque. The main aim was to determine contact pressures and forces induced at the interface between an artery wall with hypocellular and calcified plaques and an expanded stent. The results demonstrated the drawbacks of plaque calcification, which triggered a sharp contact pressure and radial force surge at the interface as well as a significant rise in von Mises stress within the vessel, potentially leading to rupture and restenosis. A regression line was then established to relate hypocellular and calcified plaques. The adjusted coefficient of determination indicated a good correlation between contact pressures for calcified and hypocellular plaque models. Regarding the directionality of wall properties, contact pressure and force observations were not significantly different between isotropic and anisotropic arteries. Moreover, variations in friction coefficients did not substantially affect the interfacial contact pressures.

Comparative Efficacy and Safety of Self-Expandable vs. Balloon-Expandable Stent Grafts in Visceral Artery Aneurysm Management.

PURPOSE: This study assesses the efficacy and safety of self-expandable (SE) versus balloon-expandable (BE) stent grafts for managing visceral artery aneurysms (VAAs), focusing on procedural success and complication rates. MATERIALS AND METHODS: We conducted a retrospective analysis of VAA patients treated at our institution from April 2006 to September 2021. The study reviewed patient demographics, aneurysm characteristics, treatment details, and outcomes, including endoleaks. RESULTS: Among the 23 patients analyzed, splenic artery aneurysms represented 44% of cases. Fifteen patients were treated with balloon-expandable stent grafts (BE SGs), and eight patients were treated with self-expandable stent grafts (SE SGs). For saccular aneurysms, the average neck size was 10.10 ± 8.70 mm in the BE group versus 18.50 ± 3.40 mm in the SE group (p = 0.23), with an average sac size of 20.10 ± 18.9 mm in the BE group versus 15.60 ± 12.7 mm in the SE group (p = 0.16). The average sac-to-neck ratio was 1.69 ± 2.23 in the BE group versus 1.38 ± 0.33 in the SE group (p = 0.63). The BE group exhibited a significantly higher endoleak rate (60%) compared to the SE group (12.5%; p = 0.03). CONCLUSIONS: While further investigation is needed to fully assess the outcomes of stent graft treatment for VAAs, initial data show a significantly higher endoleak rate with BE SGs compared to SE SGs. The SE SGs may offer better outcomes due to their superior ability to conform to tortuous and mobile visceral arteries.

Evaluation of short and mid-term clinical outcomes in patients with aortic coarctation treated with self-expandable stents.

The present study aimed to evaluate the outcomes of percutaneous treatment of aortic coarctation using self-expandable uncovered Nitinol stents. We conducted a retrospective clinical data review of all patients with aortic coarctation and treated with self-expandable uncovered Nitinol stents at our institution between 2009 and 2019. The gradient pressure across the coarctation site was measured using aortography. Follow-up echocardiography and computed tomography angiography were performed to assess possible stent complications. A total of 127 stents were successfully implanted in 125 patients (64.8% males) with a mean age of 35.36 ± 11.9 years. The gradient across the coarctation site decreased significantly from 67.48 ± 14.79 to 5.04 ± 3.01 mmHg (P < 0.001) after self-expandable stent implantation. Systolic blood pressure (SBP) decreased significantly from 175.53 ± 15.99 to 147.22 ± 12.83 mmHg (P < 0.001) after self-expandable stenting. There were no major technical or clinical complications, including balloon rupture, aneurysmal formation, infection, secondary stent migration, thrombosis, death during the procedure, and in-hospital mortality. On a mean follow-up of 48 ± 23.6 months (12-120 months), the gradient [from 59.43 ± 15.42 to 3.72 ± 1.38 mmHg (P < 0.001)] and SBP [from 175.53 ± 15.99 to 127.99 ± 7.82 mmHg (P < 0.001)] decreased significantly. There was no mortality, aneurysmal formation in the stent site, dislocation, or aortic re-stenosis requiring intervention during mid-term follow-up. Treatment of aortic coarctation using a self-expandable uncovered nitinol stent is safe and effective with promising mid-term outcomes.

Balloon-mounting stent for intracranial arterial stenosis: A comprehensive and comparative systematic review and meta-analysis.

INTRODUCTION: As one of the major causes of acute ischemic stroke, intracranial arterial stenosis necessitates an intervention that ranges from medical treatment to balloon angioplasty and stenting. Self-expandable stents (SES) and balloon-mounted stents (BMS) are two types of stents and their comparative efficacy and safety for intracranial stenosis are not well established. METHODS: Studies that investigate balloon-mounted stenting for intracranial stenosis were extracted from PubMed, Scopus, and Cochrane library. We sought to gather data on the success rate, change in mean arterial stenosis, and complications such as minor and major stroke and death (MMD), symptomatic intracranial hemorrhage, myocardial infarction, all-cause mortality, and in-stent re-stenosis. RESULTS: 3049 patients from 35 studies were included in this study. 20 studies investigated BMS alone and others compared BMS with SES. BMS was significantly more effective in reducing the degree of stenosis compared to SES (Difference in mean -5.953, CI 95% -7.727 to -4.179), had less complications compared to SES such as MMD (8.5% vs. 11.2%) and less in-stent re-stenosis (18.6% vs. 19.6%), but patients with SES experienced a lower rate of all-cause mortality(1.7% vs. 4.1%). CONCLUSION: Intracranial stenting with BMS is more effective in reducing the degree of stenosis and has lower rates of complications when compared to SES.

Viabahn-assisted sutureless anastomosis (VASA) repair of a complex internal carotid artery aneurysm.

Extracranial carotid artery aneurysms (CAAs) are extremely rare and often require surgical intervention to avoid complications such as local compression symptoms and thrombo-embolization. We present the case of a 63-year-old man with a history of hypertension, meningioma, and an incidental finding of a right saccular internal carotid artery aneurysm at the base of the skull. He underwent open surgical repair; nonetheless, end-to-end anastomosis was not feasible. As bailout, the internal carotid artery was successfully reconstructed with a novel Viabahn-assisted sutureless anastomosis technique (GORE, Viabahn). Postoperative clinical assessment revealed no complications, postoperative computed tomography angiography revealed a patent reconstruction, and the patient was discharged home uneventfully with 1-year clinical and computed tomography angiography follow-up without remarks. Hybrid procedure is a viable option for technically challenging carotid anastomoses near the skull base.

Image-guided stent-directed irreversible electroporation for circumferential ablation in the rat esophagus.

Background: Irreversible electroporation (IRE) has been investigated in the alimentary tract; however, the lack of dedicated electrodes and insufficient tissue responses made its application limited. The aim of this study was to investigate the efficacy and safety of image-guided stent-directed IRE in the rat esophagus. Methods: The bipolar self-expandable electrode (SE) was developed using the braiding technique. A finite element analysis was performed to validate optimal electrical field strength for the rat esophagus. A total of 40 out of 50 rats received stent-directed IRE and were sacrificed at 10 h, 3 days, 7 days, and 28 days of 10 each. The remaining ten rats underwent a sham procedure. The outcomes of stent-directed IRE were assessed by esophagography and histological responses. Results: Stent-directed IRE was technically successful in all rats with mild muscle contraction. The heart rate dropped immediately and gradually recovered at 180 s. TUNEL and caspase-3 with submucosal thickness significantly increased at 10 h and Day 3 compared with those of the sham control (all p < 0.001). The thickness of epithelial layers with collagen deposition significantly decreased at 10 h and Day 3 (all p < 0.001), however, increased at Day 7 compared with that of the sham control (all p < 0.05). The Ki67-positive deposition significantly increased at Day 3 and 7 compared with that of the sham control (all p < 0.001). All variables were similar to those of the sham control at Day 28. Conclusion: Image-guided stent-directed IRE was effective and safe in the rat esophagus. It seems to have effectively and evenly induced cell death and gradually recovered with cellular regeneration.

Reliable Numerical Models of Nickel-Titanium Stents: How to Deduce the Specific Material Properties from Testing Real Devices.

The current interest of those dealing with medical research is the preparation of digital twins. In this frame, the first step to accomplish is the preparation of reliable numerical models. This is a challenging task since it is not common to know the exact device geometry and material properties unless in studies performed in collaboration with the manufacturer. The particular case of modeling Ni-Ti stents can be highlighted as a worst-case scenario due to both the complex geometrical features and non-linear material response. Indeed, if the limitations in the description of the geometry can be overcome, many difficulties still exist in the assessment of the material, which can vary according to the manufacturing process and requires many parameters for its description. The purpose of this work is to propose a coupled experimental and computational workflow to identify the set of material properties in the case of commercially-resembling Ni-Ti stents. This has been achieved from non-destructive tensile tests on the devices compared with results from Finite Element Analysis (FEA). A surrogate modeling approach is proposed for the identification of the material parameters, based on a minimization problem on the database of responses of Ni-Ti materials obtained with FEA with a series of different parameters. The reliability of the final result was validated through the comparison with the output of additional experiments.

Balloon-Expandable Cheatham-Platinum Stents Versus Self-Expandable Nitinol Stents in Coarctation of Aorta: A Randomized Controlled Trial.

OBJECTIVES: This study sought to compare the safety and efficacy of the balloon-expandable stent (BES) and the self-expandable stent (SES) in the endovascular treatment of coarctation of aorta. BACKGROUND: Coarctoplasty with stents has conferred promising results. Although several nonrandomized studies have approved the safety and efficacy of the BES and the SES, no high-quality evidence exists for this comparison. METHODS: In the present open-label, parallel-group, blinded endpoint randomized pilot clinical trial, adult patients with de novo native aortic coarctation were randomized into Cheatham-platinum BES and uncovered nitinol SES groups. The primary outcome of the study was a composite of procedural and vascular complications. The secondary outcomes of the study consisted of the incidence of aortic recoarctation, thoracic aortic aneurysm/pseudoaneurysm formation, and residual hypertension at a 12-month follow-up. RESULTS: Among 105 patients who were screened between January 2017 and December 2019, 92 eligible patients (32 women [34.8%]) with a median age of 30 years (IQR: 20-36 years) were randomized equally into the BES and SES groups. The composite of procedural and vascular complications occurred in 10.9% of the BES group and 2.2% of the SES group (odds ratio: 0.18; 95% CI: 0.02-1.62; P = 0.20). Aortic recoarctation occurred in 5 patients (5.4%), 3 patients (6.5%) in the BES group and 2 patients (4.3%) in the SES group (odds ratio: 0.65; 95% CI: 0.10-4.09; P = 0.64). Only 1 patient (1.1%) was complicated by aortic pseudoaneurysm. Hypertension control was achieved in 50% of the study population, with an equal distribution in the 2 study groups at the 12-month follow-up. CONCLUSIONS: Both the BES and the SES were safe and effective in the treatment of native coarctation.

Comparison of the Covered Self-Expandable Viatorr CX Stent with the Covered Balloon-Expandable BeGraft Peripheral Stent for Transjugular Intrahepatic Portosystemic Shunt (TIPS) Creation: a Single-Centre Retrospective Study in Patients with Variceal Bleeding.

PURPOSE: This study compares the safety and efficacy of the ePTFE-covered self-expansible nitinol stent (VIATORR® Controlled Expansion, Gore, Flagstaff, USA) with the ePTFE-covered, balloon-expandable, metallic stent (BeGraft peripheral, Bentley, Hechingen, Germany) for the creation of the transjugular intrahepatic portosystemic shunt (TIPS). MATERIAL AND METHODS: From September 2016 to December 2020, 72 consecutive patients receiving TIPS for acute variceal bleeding (rescue and early TIPS, n = 15) or for prophylaxis of variceal rebleeding (n = 57) were enrolled. The main contraindications were patients with vascular liver disease (portal vein thrombosis and Budd-Chiari syndrome). Forty patients (55.6%) received a Viatorr CX stent and 32 patients (44.4%) a BeGraft peripheral stent. Safety endpoints were technical and clinical adverse events and early deaths within 30 days after TIPS implantation. Efficacy endpoints were rebleeding rates, recurrence of large varices requiring endoscopic band ligation, or TIPS revision. RESULTS: Groups receiving the Viatorr CX or BeGraft peripheral stent were comparable in all respects except the TIPS indication for acute variceal bleeding (5% vs. 25%, p = 0.015). All patients had a successful intervention, and the physical variables of stent implantation (intervention and fluoroscopy time, reduction of the portosystemic pressure gradient) as well as adjunctive embolization of varices were similar in both groups. Severe clinical complications (Viatorr CX: 5% vs. BeGraft peripheral: 3.1%, p = 0.692), post-TIPS hepatic encephalopathy (12.5% vs. 18.8%, p = 0.743) and death (5% vs. 0%, p = 0.793) were not different between Viatorr CX and BeGraft peripheral groups. With respect to efficacy, freedom from rebleeding and from variceal band ligation during follow-up (100% vs. 100%, p = 1.0), as well as the need for shunt revision (10.5% vs. 18.8%, p = 0.327), was comparable. CONCLUSION: Compared to the present gold standard, the Viatorr CX stent, the balloon-expandable BeGraft peripheral stent, showed similar results with respect to safety and efficacy.

Determination effect of two different NiTi stents on the vessel wall and studying their flexibility using finite element method.

Finite element simulation is used to analysis stent designs, extension as well as interaction between a stent and a vessel. In this paper, two different stents with different geometries have been simulated. One is Zilver stent and the other one is Navalis stent. The aim of this study is to determine the effect of stents deployment with various designs that are made of shape memory alloy (SMA) on the distribution of vessel wall stresses by using computational modeling approach. The constitutive model which described the behavior of SMA is based on Microplane model. In addition, SMA stents have been simulated under torsion loading to compare the flexibility of various designs under different conditions. The superelastic behavior and shape memory effect of SMA stents are investigated in this paper. The numerical simulation results show the different geometries of stents have significant effect on the arterial wall. The results show the Navalis stent causes less stress on the arterial wall and it is more flexible than the Zilver stent under the same torsion loading.

Numerical modeling of bare and polymer-covered braided stents using torsional and tensile springs connectors.

Computational modeling of braided stents using the finite element (FE) method has become an essential tool in the design and development of these medical devices. One of the most challenging issues in such a task is representing in an accurate manner the interaction between the interlacing wires. With the goal of achieving a compromise between accuracy and computational affordability, we propose a new approach consisting in using 1D FE formulations equipped with torsional springs at the crossover points of the wires. In the case of covered braided stents, the model is enriched with a set of tensile springs (defined in the longitudinal direction), aimed at capturing the stiffening effect of the polymeric membrane. The predictive capabilities of the proposed model are evaluated using data of our own experimental tests, as well as data from other tests in the literature. The simulations demonstrate that the proposed model is able to predict the (markedly nonlinear) behavior of stents when subjected to radial and axial cycle loads, with errors at the end of the compression stage ranging from 0.5% to 10% in all cases.

Analytical methods for braided stents design and comparison with FEA.

Braiding technology is nowadays commonly adopted to build stent-like devices. Indeed, these endoprostheses, thanks to their typical great flexibility and kinking resistance, find several applications in mini-invasive treatments, involving but not limiting to the cardiovascular field. The design process usually involves many efforts and long trial and error processes before identifying the best combination of manufacturing parameters. This paper aims to provide analytical tools to support the design and optimization phases: the developed equations, based on few geometrical parameters commonly used for describing braided stents and material stiffness, are easily implementable in a worksheet and allow predicting the radial rigidity of braided stents, also involving complex features such as multiple twists and looped ends, and the diameter variation range. Finite element simulations, previously validated with respect to experimental tests, were used as a comparator to prove the reliability of the analytical results. The illustrated tools can assess the impact of each selected parameter modification and are intended to guide the optimal selection of geometrical and mechanical stent proprieties to obtain the desired radial rigidity, deliverability (minimum diameter), and, if forming processes are planned to modify the shape of the stent, the required diameter variations (maximum and minimum diameters).

Short- and Long-Term Safety and Efficacy of Self-Expandable Leo Stents Used Alone or with Coiling for Ruptured and Unruptured Intracranial Aneurysms: A Retrospective Observational Study.

To assess the efficacy and safety of the Leo stent used alone or with coiling to treat complex intracranial aneurysms (IAs) not eligible for simple or balloon-assisted coiling, this single-center retrospective study included consecutive adults with ruptured or unruptured IAs treated in 2011-2018 by stenting with or without coiling. The indication for stenting was IA complexity precluding simple or balloon-assisted coiling. Extensive data on the patients, IAs, antiplatelet treatments, procedures, and outcomes over the first 36 months were collected. Risk factors for early complications (univariate analysis) and delayed ischemia (multivariate analysis) were sought. We include 64 patients with 66 IAs. The procedural success rate was 65/66 (98.5%). Obliteration was Raymond Roy class I or II for 85% of IAs. Six patients died including four of the 12 patients presenting with subarachnoid hemorrhage, which was the only significant risk factor for early major complications. At 1 month, 45/64 (69%) had no disabilities. No rebleeding was reported. Ischemia was detected by routine MRI in 20 (35%) of the 57 patients with long-term data and was asymptomatic in 14. The stent-within-a-stent configuration was the only independent risk factor for ischemia. The Leo stent used alone or with coils to manage challenging IAs was associated with a high procedural success rate and complete or nearly complete IA obliteration of 85% of IAs. The high frequency of ischemia is ascribable to our use of routine serial MRI. In patients with bleeding, the Leo stent was associated with an excess risk of early, major, intracranial complications, as compared to patients without bleeding. Long-term follow-up was marked by the occurrence of ischemic events in the vascular territory of the stent, mostly silent.