Experimental validation of auxetic stent designs: three-point bending of 3D printed Titanium prototypes.

Introduction: Numerical simulations have demonstrated the superior bending flexibility of auxetic stents compared to conventional stent designs for endovascular procedures. However, conventional stent manufacturing techniques struggle to produce complex auxetic stent designs, fueling the adoption of additive manufacturing techniques. Methods: In this study, we employed DMLS additive manufacturing to create Titanium Ti64 alloy stent prototypes based on auxetic stent designs investigated in a previous study. These prototypes were then subjected to experimental three-point bending tests. Result: The experimental results were replicated using a finite element model, which showed remarkable accuracy in predicting the bending flexibility of four auxetic stents and two conventional stents. Discussion: Although this validation study demonstrates the promising potential of DMLS and other additive manufacturing methods for fabricating auxetic stents, further optimization of current stent design limitations and the incorporation of post-processing techniques are essential to enhance the reliability of these additive manufacturing processes.

Delayed Stanford Type A Aortic Dissection After Endovascular Repair of Abdominal Aortic and Common Iliac Artery Aneurysms Resulting in Stent Graft Collapse: A Case Report.

We discuss a rare case of Stanford type A aortic dissection (TAAD) occurring several months after endovascular aneurysm repair (EVAR) of the abdominal aortic and the common iliac artery (CIA) aneurysms. The patient underwent urgent surgery for TAAD treatment but died on the table due to intractable bleeding. We conclude that TAAD was likely unrelated to the initial EVAR procedure but rather to atherosclerosis, hypertension, and prior aortic valve replacement. Only a few cases in the literature report TAAD and total collapse of the abdominal aortic stent graft.

Implications and late outcomes of type II endoleaks after endovascular aneurysm repair.

OBJECTIVE: Type II endoleaks (T2ELs) are the most common cause of reintervention after endovascular aneurysm repair (EVAR). Although most resolve spontaneously, the long-term implications of T2ELs remain elusive. We aim to evaluate the impact of persistent and late T2ELs on clinical outcomes after EVAR. METHODS: This was a single-institution retrospective review of patients who underwent EVAR for degenerative infrarenal abdominal aortic aneurysm between January 2010 and June 2022 with no type I (T1EL) or III (T3EL) endoleak seen at EVAR completion. Patients were categorized based on T2EL status. Group 1 included patients with never detected or transient T2ELs (detected at EVAR completion but not after). Group 2 encompassed persistent T2ELs (seen at EVAR completion and again during follow-up) and late T2ELs (detected for the first time at any point during follow-up). Time-to-event analysis was conducted using a time-dependent approach to T2EL status. Primary outcomes included freedom from sac enlargement (SE), aneurysm-related reinterventions, and overall survival. RESULTS: A total of 803 patients met inclusion criteria. Group 1 included 418 patients (52%), of which 85% had no T2ELs and 15% had transient T2ELs. Group 2 had 385 patients; 23% had persistent T2ELs, and 77% developed a new T2EL. Patients in group 1 had a higher prevalence of smoking (88% vs 83%; P < .001), chronic obstructive pulmonary disease (33% vs 25%; P = .008), chronic kidney disease (13% vs 8%; P = .021), and a higher mean Society for Vascular Surgery score (7 vs 6 points; P = .049). No differences were found in aneurysm diameter or morphology. Mean follow-up was 5 years for the entire cohort. In Group 2, 58 patients (15%) underwent T2EL treatment, most commonly transarterial embolization. At 10 years after EVAR, Group 2 was associated with lower freedom from SE (P < .001) and abdominal aortic aneurysm-related reinterventions (P < .001) and comparable overall survival (P = .42). More T1ELs were detected during follow-up in Group 2 (6 [1%] vs 20 [5%]; P = .004), with 15 (75%) of these detected at a median of 3 years after the T2EL. No difference between groups was observed in explant (0.7% vs 2.1%; P = .130) or aneurysm rupture (0.5% vs 1.3%; P = .269) rates. CONCLUSIONS: One-half of patients treated with infrarenal EVAR developed persistent/late T2ELs, which are associated with a higher risk of SE and reinterventions. No difference in overall survival or aneurysm rupture risk was seen at 10 years, based on T2EL status or T2EL intervention. A conservative approach to T2ELs may be appropriate for most patients with absent T1ELs or T3ELs.

Endovascular retrieval of a migrated covered stent from the pulmonary artery.

Stent migration is a rare but significant complication following endovascular procedures. Techniques for managing dislodged stents have included surgical, endovascular, and conservative approaches. This case details a patient who had a covered stent placed within the left renal vein which later migrated to the pulmonary artery causing damage to the tricuspid valve. The migrated stent was successfully removed using a percutaneous endovascular approach utilizing fluoroscopy and transesophageal echocardiogram guidance.

Totally percutaneous endovascular renal allograft salvage for common iliac artery pseudoaneurysm.

Delayed presentation of recipient artery pseudoaneurysms following kidney transplantation is a rare, yet critical, complication. Although the precise etiology remains unclear, factors such as chronic steroid use, iatrogenic injuries (including vascular clamp damage during index surgery), or infections could contribute. Timely surgical intervention is imperative to prevent arterial rupture and life-threatening bleeding. Open repair, although commonly used, is associated with notable mortality rates and graft loss. Endovascular repair for delayed presentations of native iliac artery pseudoaneurysms has seen limited documentation in the literature. We present a case involving salvage of a kidney graft through innovative application of an endovascular technique using a modified stent graft with fenestration for the transplanted renal artery. The pseudoaneurysm, discovered 4 years after transplantation, was situated in proximity to the anastomosis site of the kidney graft's renal artery to recipient common iliac artery. Traditional open repair posed significant risks of graft loss due to its location near the kidney allograft. Our approach successfully resolved the issue, preserving graft function and resulting in a short length of hospital stay. This case contributes to the limited body of knowledge on delayed presentation of pseudoaneurysms after kidney transplantation. Successful application of an endovascular approach underscores its potential as a safe and effective alternative to open repair, offering favorable outcomes in terms of patient morbidity, mortality, and graft salvage.

Systematic review and meta-analysis of current evidence in endograft therapy for spontaneous isolated superior mesenteric artery dissection.

The role of endovascular stent therapy (EST) in the treatment of spontaneous isolated superior mesenteric artery dissection (SISMAD) has gained momentum in recent years but remains controversial. We gathered research examining the advantages and disadvantages of EST for SISMAD patients. Primary outcomes involved both immediate and long-term results. Random or fixed effect models were used for effect size (ES) calculation with 95% confidence interval (CI) based on 50% heterogeneity threshold. Our analysis incorporated data from 21 studies including 611 SISMAD cases treated by EST. Our findings show a complication rate of approximately 1% following EST (95%CI 0.01-0.02, I2 = 0%, P = 0.97), with a bare minimum mortality rate of < 1% (95%CI 0.00-0.01, I2 = 0%, P > 0.05) and a reintervention rate of < 1% (95%CI 0.00-0.01, I2 = 0%, P = 0.89). We also found technique success and symptom resolution approaching 94% and 99%, respectively, in the immediate postoperative phase. In the long run, we observed a recurrence of symptoms at 3% (95%CI 0.00-0.06, I2 = 58.6%, P < 0.01), creation of new dissections at 1% (95%CI 0.00-0.02, I2 = 0%, P = 0.73), aneurysm progression at 2% (95%CI 0.00-0.03, I2 = 42.7%, P = 0.12), reintervention due to complications at 3% (95%CI 0.00-0.05, I2 = 0%, P = 0.43) and stenotic stents at 12% (95%CI 0.04-0.23, I2 = 77.5%, P < 0.01). Nevertheless, high levels of stent patency 98% (95% CI 0.97-1.00, I2 = 0%, P = 0.51) and complete remodeling 88% (95% CI 0.82-0.94, I2 = 65.5%, P < 0.05) were observed postoperatively. Overall, EST presents minimal complications and promising long-term outcomes for SISMAD, although the prevalence of stent stenosis requires further attention.

Impact of Perivascular Adipose Tissue on Neointimal Formation Following Endovascular Placement.

Following the placement of endovascular implants, perivascular adipose tissue (PVAT) becomes an early sensor of vascular injury to which it responds by undergoing phenotypic changes characterized by reduction in the secretion of adipocyte-derived relaxing factors and a shift to a proinflammatory and pro-contractile state. Thus, activated PVAT loses its anti-inflammatory function, secretes proinflammatory cytokines and chemokines, and generates reactive oxygen species, which are accompanied by differentiation of fibroblasts into myofibroblasts and proliferation of smooth muscle cells. These subsequently migrate into the intima, leading to intimal growth. In addition, periadventitial vasa vasorum undergoes neovascularization and functions as a portal for extravasation of inflammatory infiltrates and mobilization of PVAT resident stem/progenitor cells into the intima. This review focuses on the response of PVAT to endovascular intervention-induced injury and discusses potential therapeutic targets to suppress the PVAT-initiated pathways that mediate the formation of neointima.

Transcranial Doppler emboli monitoring for stroke prevention after flow diverting stents.

OBJECTIVE: Flow diverting stents (FDS) are increasingly used for the treatment of intracranial aneurysms. While FDS can provide flow diversion of parent vessels, their high metal surface coverage can cause thromboembolism. Transcranial Doppler (TCD) emboli monitoring can be used to identify subclinical embolic phenomena after neurovascular procedures. Limited data exists regarding the use of TCDs for emboli monitoring in the periprocedural period after FDS placement. We evaluated the rate of positive TCDs microembolic signals and stroke after FDS deployment at our institution. METHODS: We retrospectively evaluated 105 patients who underwent FDS treatment between 2012 and 2016 using the Pipeline stent (Medtronic, Minneapolis, MN, USA). Patients were pretreated with aspirin and clopidogrel. All patients were therapeutic on clopidogrel pre-operatively. TCD emboli monitoring was performed immediately after the procedure. Microembolic signals (mES) were classified as "positive" (<15 mES/hour) and "strongly positive" (>15 mES/hour). Clinical stroke rates were determined at 2-week and 6-month post-operatively. RESULTS: A total of 132 intracranial aneurysms were treated in 105 patients. TCD emboli monitoring was "positive" in 11.4% (n=12) post-operatively and "strongly positive" in 4.8% (n=5). These positive cases were treated with heparin drips or modification of the antiplatelet regimen, and TCDs were repeated. Following medical management modifications, normalization of mES was achieved in 92% of cases. The overall stroke rates at 2-week and 6-months were 3.8% and 4.8%, respectively. CONCLUSIONS: TCD emboli monitoring may help early in the identification of thromboembolic events after flow diversion stenting. This allows for modification of medical therapy and, potentially, preventionf of escalation into post-operative strokes.

Successful endovascular treatment of an obstruction following the surgical repair of a traumatic portal vein injury: a case report.

Traumatic portal vein injury is rare, but the associated mortality rate ranges from 50% to 70%. The management of this injury is difficult and remains controversial. In this case report, we describe the successful endovascular treatment of an obstruction that developed following the surgical repair of a traumatic portal vein injury. A man in his mid-40s who had been injured in a car accident presented to our trauma center with abdominal pain, abdominal distension, and open wounds over both knees. Emergency laparotomy revealed a longitudinal rupture from the upper border of the pancreas to the mid-portion of the portal vein; his hemorrhage was successfully controlled surgically. However, postoperative abdominal computed tomography imaging revealed portal vein obstruction. One week after admission to the intensive care unit, an endovascular stent was successfully inserted into the patient's portal vein via a percutaneous transhepatic approach. The associated injuries, including the distal common bile duct obstruction, were successfully managed by choledochojejunostomy. The patient's postoperative recovery was uneventful. Thus, endovascular stent placement is an effective and safe means of treating an obstruction following the surgical repair of a traumatic portal vein injury.

Outcomes in patients managed with endovascular stent for malignant superior vena cava syndrome.

Background: Malignant Superior Vena Cava Syndrome (SVCS) corresponds to the clinical manifestations due to the restriction of venous return to the right atrium secondary to obstruction of the superior vena cava and/or its main tributaries for a tumor. Endovascular management has proven to be safe, effective and cause a fast symptomatic relief in patients with SVCS. There is limited evidence in factors associated with outcomes in malignant setting for this procedure. Materials and methods: An analytical retrospective study was conducted and included patients that underwent endovascular management for malignant SVCS at the National Cancer Institute of Colombia between May 2016 and May 2021. Clinical and technical variables were analyzed to found associations with outcomes in these patients. Results: 54 patients were analyzed. Successful procedure rate was 94.4 %. At 10 months, the OS of the entire cohort of patients was 25 %. Patients with breast or lung cancer (P = 0.031), unsuccessful procedure (P = 0.011), and also with short time of symptoms to the date of the endovascular procedure (P = 0.027) had worse OS. Multivariate analysis showed that lung cancer [HR = 2.55, 95%IC:(1.21-5.36)] and left internal jugular vein or left Innominate vein distal stent attachment [HR = 3.27, 95%IC:(1.31-8.15)] were independent factors for worst OS. Conclusions: Based in the high success rate of the endovascular management and the better outcome in patients with early and successful procedure, this procedure should be considered as part of the multimodal treatment in patients with SVCS independent of the clinical scenario and the oncological diagnosis.

Unveiling a pseudoaneurysm at the anastomosis site in a transplanted kidney: An initial misclassification as hydro nephrosis - A case report and literature review.

A 31-year-old woman who developed large Psudoaneurysm after kidney transplantation is discussed. The patient was presented with an 11 cm mass, which became larger gradually. Minimally invasive endovascular stent graft placement was successfully done.

Using Fenestrated Stent to Increase the Flow of Extracorporeal Membrane Oxygenation of Superior Vena Cava Compression Syndrome.

Superior vena cava syndrome (SVCS) is an obstruction of the venous return through the superior vena cava (SVC) or any other significant branches. The obstruction may be external, like thoracic mass compressing the SVC, or internal, like thrombosis or tumor, which directly invades the SVC. Patients experiencing a medical emergency after being initially stabilized require treatment for SVCS, including endovenous recanalization and the implantation of an SVC stent to reduce the risk of abrupt respiratory arrest and death. A 54-year-old female presented from the university medical center with weight loss and solid food dysphagia for three months. Chest-CT scan showed a mediastinal mass of 10 x 9 x 8 cm. A transbronchial biopsy was attempted. The patient was arrested during the bronchoscopy lab procedure. Cardiopulmonary resuscitation (CPR) was initiated, and venoarterial-extracorporeal membrane oxygenation (VA-ECMO) was done through the right femoral artery cannula size 15 Fr due to the narrowing of the artery and the left femoral vein cannula size 23 Fr. During the night shift, the ECMO flow was hard to maintain with fluids, which was realized with the ECMO outflow volume issue. The next day, in the hybrid operating room, a fenestrated SVC stent was placed in the SVC, brachiocephalic, and internal jugular veins. The patient's hemodynamics improved post-stenting, especially ECMO outflow. This case illustrates that stenting in SVCS is a valid therapeutic option to increase the ECMO flow in this patient group.

Superior Vena Cava Syndrome: An Umbrella Review.

Superior vena cava syndrome (SVCS) is a medical emergency that encompasses an array of signs and symptoms due to obstruction of blood flow through the superior vena cava (SVC). It poses a significant healthcare burden due to its associated morbidity and mortality. Its impact on the healthcare system continues to grow due to the increasing incidence of the condition. This incidence trend has been attributed to the growing use of catheters, pacemakers, and defibrillators, although it is a rare complication of these devices. The most common cause of SVCS remains malignancies accounting for up to 60% of the cases. Understanding the pathophysiology of SVCS requires understanding the anatomy, the SVC drains blood from the right and left brachiocephalic veins, which drain the head and the upper extremities accounting for about one-third of the venous blood to the heart. The most common presenting symptoms of SVCS are swelling of the face and hand, chest pain, respiratory symptoms (dyspnea, stridor, cough, hoarseness, and dysphagia), and neurologic manifestations (headaches, confusion, or visual/auditory disturbances). Symptoms generally worsen in a supine position. Diagnosis typically requires imaging, and SVCS can be graded based on classification schemas depending on the severity of symptoms and the location, understanding, and degree of obstruction. Over the past decades, the management modalities of SVCS have evolved to meet the increasing burden of the condition. Here, we present an umbrella review providing an overall assessment of the available information on SVCS, including the various management options, their indications, and a comparison of the advantages and disadvantages of these modalities.

Ventriculo-inferior-venacaval shunt salvage via endovascular surgery.

INTRODUCTION: Hydrocephalus treatment can be very challenging. While some hydrocephalic patients can be treated endoscopically, many will require ventricular shunting. Frequent shunt issues over a lifetime is not uncommon. Although most shunt malfunctions are of the ventricular catheter or valve, distal failures occur as well. A subset of patients will accumulate non-functioning distal drainage sites. CASE DESCRIPTION: We present a 27-year-old male with developmental delay who was shunted perinatally for hydrocephalus from intraventricular hemorrhage of prematurity. After failure of the peritoneum, pleura, superior vena cava (SVC), gallbladder, and endoscopy, an inferior vena cava (IVC) shunt was placed minimally-invasively via the common femoral vein. We believe this is only the eighth reported ventriculo-inferior-venacaval shunt. IVC occlusion years later was successfully treated with endovascular angioplasty and stenting followed by anticoagulation. To our knowledge, a ventriculo-inferior-venacaval shunt salvaged by endovascular surgery has not been previously described in the literature. CONCLUSION: After failure of the peritoneum, pleura, SVC, gallbladder, and endoscopy, IVC shunt placement is an option. Subsequent IVC occlusion can be rescued by endovascular angioplasty and stenting. Anticoagulation after stenting (and potentially after initial IVC placement) is advised.

Chronic Mesenteric Ischemia in a Patient With Limited Systemic Sclerosis.

Chronic mesenteric ischemia typically develops secondary to the development of atherosclerosis within mesenteric vessels leading to the insufficient blood supply. While autoimmune conditions are an established independent risk factor for developing atherosclerotic plaques, the association between scleroderma and chronic mesenteric ischemia has been less studied. We present a case of a 64-year-old female with limited systemic sclerosis and atherosclerotic cardiovascular disease who presented to the Gastroenterology Clinic with progressive abdominal pain who was subsequently diagnosed with chronic mesenteric ischemia secondary to superior mesenteric artery stenosis and successfully treated with endovascular stenting.

Innovative Approach to Manage Transcatheter Aortic Valve Embolization.

We describe the case of a patient with an ascending aortic aneurysm who underwent valve-in-valve transcatheter aortic valve implantation, which was complicated by valve embolization. After a multidisciplinary discussion and an innovative approach, the free-floating embolized valve was anchored securely in the aortic arch with an uncovered aortic endovascular stent. (Level of Difficulty: Intermediate.).

May-Thurner Syndrome: A Suspicion That Led to an Incidental Discovery.

May-Thurner syndrome (MTS)/Iliac vein compression syndrome is characterized by left iliac vein stenosis secondary to compression by the right common iliac artery against the fifth-lumbar vertebra. It increases the incidence of deep venous thrombosis (DVT). We had a 43-year-old female presenting with left leg swelling and was found to have extensive DVT provoked by a long history of travel. Because of the extension of her thrombus, a catheter-guided thrombectomy (CDT) was planned and findings of MTS were identified incidentally. She had an endovascular stent placed and was discharged on long-term anticoagulation.