Bare Stents Research Articles

Computational Investigation and Histopathological Validation of Interaction Between Stent Graft and Aorta in Retrograde Type A Dissection After TEVAR in Canine Models

Purpose: Retrograde type A dissection (RTAD) after thoracic endovascular aortic repair (TEVAR) has been a major drawback of endovascular treatment. To our knowledge, no studies have simulated and validated aortic injuries caused by stent grafts (SGs) in animal models. Therefore, the aim of this study was to evaluate and quantify the SG–aorta interaction through computational simulations and to investigate the underlying mechanism through histopathological examinations. Methods: Two custom-made Fabulous® (DiNovA Meditech, Hang Zhou, China) SGs were implanted in 2 canine aortas with a 5-mm difference in the distance in landing locations. The aortic geometries were extracted from RTAD and non-RTAD cases. A computational SG model was assembled based on the implanted SG using the software Pro-ENGINEER Wildfire 5.0 (PTC Corporation, Needham, Mass). TEVAR simulations were performed 7 times for each canine model using Abaqus software (Providence, RI, USA), and the maximum aortic stress (MAS) was calculated and compared among the groups. Three months after SG implantation, the canine aortas were harvested, and were examined using hematoxylin and eosin staining and Elastica Van Gieson (EVG) staining to evaluate histopathological changes. Results: In the computational models for both canines, MAS was observed at the proximal bare stent (PBS) at aortic greater curve. The PBS generated higher stress toward the aortic wall than other SG parts did. Moreover, the MAS was significantly higher in canine No.1 than in canine No.2 (0.415±0.210 versus 0.200±0.160 MPa) (p<0.01). Notably, in canine No.1, an RTAD developed at the MAS segment, and histopathological examinations of the segment showed an intimal flap, a false lumen, elastin changes, and medial necrosis. RTAD was not observed in canine No.2. In both SG-covered aortas, medial necrosis, elastic fiber stretching, and inflammatory infiltration were seen. Conclusion: The characteristic MAS distribution remained at the location where the apex of the PBS interacted with the aortic wall at greater curve. RTAD histopathological examinations showed intimal damage and medial necrosis at the proximal landing zone, at the same MAS location in computational simulations. The in vivo results were consistent with the computational simulations, suggesting the MAS at greater curve may cause RTAD, and the potential application of computational simulation in the mechanism study of RTAD.

The Reversed STABILISE Technique

A 64 year old man presented with acute abdominal and chest pain. (A) Computed tomography angiography showed an 84 mm infrarenal aortic aneurysm with retrograde aortic dissection arising from the aneurysm (blue arrow, entry tear) to the middle of the thoracic aorta (red arrows, dissection limits). Owing to persistent abdominal pain, he underwent endovascular aortic repair using an infrarenal bifurcated stent graft (WL Gore, Flagstaff, AZ, USA), followed by bare stenting of the upper abdominal and descending aorta (Cook Medical, Bloomington, IN, USA). Both grafts were expanded as per the STABILISE technique, allowing complete exclusion of the aneurysm and dissection (B).

Late onset infection of covered and bare metal arterial stents.

The objective was to present the case of a late covered iliac stent late infection and report a comprehensive literature review on diagnosis and outcomes in this setting. A comprehensive review of the literature was performed through MedLine by two independent reviewers from 1990 to 2020 on reported cases of arterial stent late onset infection over arterial stents. The data about on the risk factors, clinical presentation, treatment and outcomes were collected. Twenty-two studies were selected as pertinent for the analysis, totalling 24 patients including the indexed case. Infection occurred at a median of 22months postoperatively (range 2-120months) over a bare metal stent in 66.7% (n 16) of cases versus 33.3% (n 8) over a covered stent. Clinical presentation included local symptoms (local pain, oedema, petechiae or skin rash) in 21 (87.5%) cases and non-specific systemic symptoms (fever, sepsis, chills and leucocytosis) in 8 cases (33.3%). In 4 cases (16.7%), patients presented with haemorrhagic shock upon arterial rupture. The bacteria most frequently encountered were S. aureus (54.2% of cases). Several factors were supposed to be responsible for the infection including among which procedure-related (non-aseptic technique, lack of prophylactic antibiotics and repetitive punctures at the access site) or related to pre-existing patient's clinical conditions (immunosuppression, diabetes and concurrent infection) have been considered responsible for the infection. Treatment consisted in antibiotics alone (2 patients, 8.3%) or in association with surgical explant, both with or and without revascularization (n 21, 87.5%). In one case, an endovascular coiling was performed. Complications occurred in 29.2% (n 7) of cases and included the need for amputation, bowel resection, endocarditis, pulmonary failure or pneumonia. Overall, three patients (12.5%) died from a septic shock or multi-organ failure. Intravascular stent infection is a rare but fearsome condition associated with high morbidity and mortality.

Short Term Outcomes of Distal Extended EndoVascular Aortic Repair (DEEVAR) Petticoat in Acute and Subacute Complicated Type B Aortic Dissection

The aim of this study was to evaluate the peri-operative and short term results of institutional experience with the Distal Extended EndoVascular Aortic Repair PETTICOAT (DEEVAR PETTICOAT) procedure. This was a single centre, observational study. From January 2015 to December 2019, 53 patients were admitted to the institution for treatment of acute and subacute complicated type B aortic dissection. Among them, data on 16 patients deemed suitable for a PETTICOAT procedure extended at infrarenal and iliac level by means of a bifurcated endograft were prospectively collected. Patients with persistent pain, visceral or lower limb malperfusion, true lumen collapse, and distal extension with computed tomography angiography (CTA) evidence of entry tears in the infrarenal or iliac zone were included. A CTA scan was performed in all patients at the baseline, before hospital discharge and then at six and 12 months post-operatively to assess aortic remodelling. Complete aortic remodelling was defined as stable aortic size (maximum enlargement < 5 mm) with complete true lumen re-expansion and complete false lumen exclusion or disappearance. Technical success was obtained in all patients. One patient (7%) had intra-operative infrarenal aortic rupture during balloon dilation of the distal end of the bare stent, successfully treated by deployment of a bifurcated endograft. Additional covered stenting of the visceral arteries was necessary in nine patients (56%) and malperfusion resolved immediately in all cases. There were no spinal cord ischaemia or other peri-procedural complications, and no post-operative death, stroke, paraplegia/paraparesis, or acute renal failure was observed. Follow up ranged from one month to 24 months (median 7.5 months). One patient (7%) with a history of drug abuse died from sepsis. At the last CTA check, all patients showed complete remodelling of the thoraco-abdominal aorta and iliac arteries without vessel enlargement. The present findings suggest that the DEEVAR PETTICOAT procedure provides effective sealing of all distal tears without increased risk of major peri-procedural complications. Further studies with larger number of patients and longer follow up are needed to confirm the safety and durability of this technique.

Intraoperative Stent-Graft-Induced Aortic Intimal Intussusception During TEVAR for Type B Aortic Dissection

Background: Aortic intimal intussusception is well described in the natural progression of type A aortic dissection. Only 3 cases of aortic intimal intussusception were reported to be related to thoracic endovascular aortic repair (TEVAR) for Stanford type B aortic dissection. In our study, we are reporting a rare but potentially fatal complication, the intraoperative stent-graft (SG)-induced aortic intimal intussusception (ISAII); this study reports a series of endovascular repair for ISAII cases. By presenting the ISAII definition, the diagnostic steps to rule out or to identify the condition, and the techniques to resolve it, we intended to raise the awareness of this severe complication, so that physicians can adapt to overcome the complications while performing TEVAR. Materials and Methods: ISAII was defined as the partial or circumferential disruption of the distal intimal flap as an intraoperative complication of endovascular treatment. From January 2014 to June 2020, 1,096 patients underwent TEVAR for Stanford type B aortic dissection at our hospital. Among them, 14 ISAII complications were witnessed. All these patients underwent endovascular repair for ISAII lesions, and their data were extracted for analysis. Results: The ISAII lesions were classified into 3 types according to their location in different aortic segments: type I, ISAII was limited within the intended SG coverage segment; type II, ISAII occurred after SG introduction or deployment, and the detached intimal flap extended beyond the intended SG coverage segment but did not affect the abdominal aortic visceral branches; type III, ISAII occurred during SG introduction or deployment, and the detached intimal flap descended to the abdominal aortic segment with visceral branches. Our results showed ISAII as a rare complication with an incidence of 1.28% (14/1096), and endovascular repair for all types of ISAII is an effective treatment. With a mean follow-up of 27.36 months (range 5–71 months), all the ISAII lesions were stable, and all the major aortic branches, SGs, and bare stents were patent. Conclusions: The management of this potentially devastating intraoperative complication relies on accurate diagnosis and prompt management. Our results suggested that endovascular repair for ISAII is effective and durable for correcting this complication. Graphical

Ruptured Aortic Aneurysm Post Occluded Stent Graft

A 67 year old man presented with back pain eight years after endovascular aortic repair with a Zenith LP graft (Cook Medical, QLD, Australia) for an asymptomatic 75 mm infrarenal aortic aneurysm. The stent graft had thrombosed one year previously, for which he underwent an axillobifemoral bypass. Computed tomography angiography (A and B) showed an 82 mm infrarenal abdominal aortic aneurysm with type 1a endoleak and a contained rupture at the level of the bare top stent (indicated by arrows). He underwent open semi-conversion with graft salvage. His post-operative course was uneventful and follow up imaging noted a decrease in aneurysm size.Image 1

MO770BARE METAL STENTS IN HD PATIENTS WITH CENTRAL VEIN STENOSES: TO STENT OR NOT TO STENT, THAT IS THE QUESTION

Abstract Background and Aims According to the current KDIGO guidelines, angioplasty should be preferred procedure for treatment of CVS instead of the bare metal stents or self-expanding stent-grafts placement. However, bare stents are still significantly more affordable than stent grafts. Aim: comparative analysis of the results of isolated balloon angioplasty (BA) and combined technique (BA with a stent placement in HD patients with central vein stenosis (CVS). Method A retrospective study included 62 patients with functional AVF and confirmed CVS: subclavian, brachiocephalic veins, vena cava inferior, or multiple lesions. In 39 patients, stents were not used; isolated balloon angioplasty (BA) was performed. In 23 patients we used bare metal stents during the first endovascular treatment. Results The use of stents leads to increase of primary patency (the time interval between the first and second endovascular interventions) – fig. 1A; HR (BA only vs. stenting) 2.064 [95% CI 1.252; 3.404], p = 0.0017. The use of stents allows to increase secondary patency (the time interval between the first endovascular intervention and the complete cessation of the use of AVF): HR=2.03 [95% CI 1.232; 3.347], p = 0.0021; fig 1B. Total need for surgical interventions did not differ: BA only 1.511 [95% CI 1.225; 1.843] and BA+stenting 1.277 [95% CI 0.997; 1.611] per 10 patient-months, incidence rate ratio 1.183 [95% CI 0.872; 1.612] p=0.2822. The second isolated BA allowed to increase patency compared to the first (HR of AVF function loss or relapse 0.512 [95% CI 0.32; 0.818], log rank p=0.001), and the third compared to the second isolated BA (HR=0.607 [95% CI 0.384; 0.959], log rank p=0.0157). The fourth isolated BA also showed a slight increase in AVF patency, but in this case we observed no significant difference with the previous intervention (HR= 0.783 [95% CI 0.501; 1.225], log rank p=0.2433). In the case of BA+stenting, the second intervention, which was consisted of stent recanalization, allowed to increase patency of the AVF (HR= 0.433 [95% CI 0.231; 0.813], log rank p= 0.0014), but the third intervention was no longer accompanied by a significant increase in patency (HR= 0.873 [95% CI 0.489; 1.558], log rank p= 0.629) and AVF function was completely lost. Conclusion The use of stents leads to a moderate increase in the median patency of AVF and a significant increase in the proportion of patients with functional AVF in the long-term period. However, repeated surgeries are significantly less effective than in a case of isolated BA. Therefore, we consider isolated BA to be the optimal treatment strategy, and stenting should be used only if the isolated BA does not result in clinical improvement. Multiple endovascular interventions can extend the duration of AVF functioning, however, in our study, AVF function was completely lost up to 52 months after the clinical manifestation of CVS in all patients. Thus, isolated BA and BA combined with a bare metal stent placement cannot be considered as a definitive treatment of CVS. Endovascular interventions provide only the necessary amount of time to create vascular access on the contralateral side or for shift of modality of renal replacement therapy.

Effect of Stent Strut Interval on Neointima Formation After Venous Stenting in an Ovine Model

The impact of stent design on venous patency is not well studied. The purpose of this study was to investigate the effect of stent material burden on endothelial coverage of stented venous segments, which may contribute to vessel healing and patency. Segmented self expanding bare nitinol stents (18× 50 mm) comprising 5 mm long attached metallic rings separated by 2, 5, or 8 mm gaps were implanted in the inferior vena cava (IVC) of 10 sheep. These stents were designed and manufactured for the purposes of this study. At six, 12, and 24 weeks after implantation the animals were euthanised and the stented vessels harvested for histomorphometric analysis. Three sections from the metallic part as well as the gaps between the struts were reviewed for quantification of endothelialisation after six, 12, and 24 weeks. The intimal thickness over and between the stent struts was measured. The endothelialisation score (graded from 1 for complete luminal endothelialisation to 5 for absence of endothelial cells) was determined. All stents were successfully deployed and all 10 sheep survived until the time of harvesting. Macroscopic inspection after 24 weeks showed only partial endothelialisation over stents with 2 mm and 5 mm skipped segments, whereas the stents with 8 mm skipped segments were totally incorporated into the vein wall. After 24 weeks, the mean (SD) neointimal thicknesses over stent struts with 2 mm, 5 mm, and 8 mm skipped segments were 254.0 (51.6), 182.2 (98.1), and 194.6 (101.1) μm, respectively. Comparison of endothelialisation scores of stents over time showed statistically significantly better endothelialisation over stents with 8 mm gaps after 12 and 24 weeks. Stent designs providing structural support to veins with larger gaps between the scaffold material appear to lead to faster and more complete endothelialisation as well as a thinner intimal layer.

Corrosion behavior of Mg wires for ureteral stent in artificial urine solution

Ureteral stents are a relatively new potential application for biodegradable Mg alloys. In this study, the corrosion behavior of Mg-1Zn wires and pure Mg wires in artificial urine solution (AUS) is investigated. It is found that AUS possesses a strong pH buffer effect. Hydrogen evolution measurement cannot be used for Mg corrosion test in this AUS due to the oxygen scavenging effect of sulfite, which is a component of AUS. The corrosion products consist of two layers, MgNH4PO4·6H2O and Mg(OH)2. The partially protective MgNH4PO4·6H2O slows down the Mg corrosion, but it indicates the encrustation risk on bare Mg-based ureteral stents.

EG Coated Stents Exhibit Enhanced Endothelial Wound Healing Characteristics

PurposeDespite their widespread use, a significant fraction of coronary stents suffer from in-stent restenosis and stent thrombosis. Stent deployment induces extensive injury to the vascular endothelium. Rapid endothelial wound closure is essential for the success of a stenting procedure. A recent study has demonstrated that the BuMA Supreme® sirolimus-eluting stent exhibits particularly attractive strut coverage characteristics. A unique feature of this stent is the presence of a thin brush layer of poly-butyl methacrylate (PBMA), covalently bonded to the stent’s cobalt-chromium frame via electro-grafting (eG™). The present study aimed to determine whether the PBMA coating has an effect on endothelial cell wound healing and stent strut coverage.MethodsWe used an in vitro coronary artery model whose wall consisted of an annular collagen hydrogel and whose luminal surface was lined with a monolayer of endothelial cells. Mechanical wounding of the endothelial lining was preformed prior to deployment of a bare cobalt-chromium stent either with or without the PBMA layer. The migration of fluorescently labeled endothelial cells was monitored automatically over a period of 48 h to determine endothelial wound healing rates.ResultsQuantitative assessment of endothelial wound healing rates within the simulated arterial model is achievable using automated image analysis. Wound healing is significantly faster (44% faster at 48 h) for stents with the PBMA eG Coating™ compared to bare metal stents.ConclusionThe PBMA eG Coating™ has the effect of promoting endothelial wound healing. Future studies will focus on elucidating the mechanistic basis of this observation.

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.

Bronchial stenting in infants with severe bronchomalacia: Technique and outcomes

ObjectivesTo report the first use of a balloon expandable bare metal stent for treating infant bronchomalacia. BackgroundInfant bronchomalacia often requires prolonged mechanical ventilation and can be life-threatening. Effective treatment for severe infant bronchomalacia continues to be elusive. We present three cases of bronchial stenting for no-option or treatment refractory infant bronchomalacia. MethodsThree consecutive cases of stenting to relieve conservative treatment refractory severe infant bronchomalacia were performed between February 2019 and December 2020. Initial diagnosis was confirmed with Computed Tomography (CT) angiography. Patients underwent rigid micro laryngoscopy, bronchoscopy, and flexible bronchoscopy to evaluate the airway. Initial conservative management strategies were pursued. Patients failing initial conservative management strategies were considered for rescue bronchial stenting. ResultsOur initial clinical experience with a coronary bare metal stent for these procedures has been favorable. The stent was easy to deploy with precision. We did not encounter stent embolization or migration. There was sufficient stent radial strength to relieve bronchomalacia without causing restenosis or erosion. There was no significant granulation tissue formation. In one patient, the stent was removed after 12 months of somatic growth; this was uneventful and bronchial patency was maintained. There were no complications in any of our patients regarding stent placement and reliability. ConclusionIn cases of three infants with severe bronchomalacia, we found that bronchial stenting with the bare metal coronary stent was effective in relieving bronchial stenosis.

Venous stent versus conventional stent for the treatment of central vein obstruction in hemodialysis patients: a retrospective study

Endovascular treatment is a first-line treatment for upper thoracic central vein obstruction (CVO). Few studies using bare venous stents (BVS) in CVO have been conducted. To evaluate the treatment performance of upper thoracic central vein stenosis between BVS and conventional bare stent (CBS) in hemodialysis patients. Hemodialysis patients with upper thoracic central vein obstruction who underwent endovascular treatment at the interventional unit of our institution from 1 January 2008 to 31 December 2018 were enrolled in the present study. CBS was used to treat central vein obstruction in 43 patients and BVS in 34 patients. We compared the primary patency rates and complications between the two stent types. P values < 0.05 were considered statistically significant. The patient demographic data between the CBS and BVS groups were similar. The characteristics of the lesions, procedures, and complications were not significantly different between the two groups (P > 0.05). There were no statistically significant differences of primary patency rates at three and six months between the BVS and CBS groups (94.1% vs. 86.0% and 73.5% vs. 58.1%, respectively; P > 0.05). The primary patency rate at 12 months in the BVS group was significantly higher than that in the CBS group (61.8% vs. 32.6%; P = 0.008). Endovascular treatment of central vein obstruction with BVS provided a higher primary patency rate at 12 months than CBS.

Selective inhibition effects on cancer cells and bacteria of Ni–Ti–O nanoporous layers grown on biomedical NiTi alloy by anodization

Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer, but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer and antibacterial properties to inhibit cancer/bacteria invasion. The present work aims at endowing the NiTi alloy with anticancer and antibacterial abilities by surface modification. Ni–Ti–O nanoporous layers with different thicknesses were prepared on NiTi by anodization, and biological experiments were conducted to evaluate the effects on gram-positive Staphylococcus aureus, human lung epithelial cancer cells (A549), as well as human endothelial cells (EA. hy926). The nanoporous layer with a thickness of 10.1 μm inhibits growth of cancer cells and kill bacteria but shows little adverse effects on normal cells. Such selectivity is related to the larger amount of Ni ions leached from the sample in the acidic microenvironment of cancer cells in comparison with normal cells. The Ni–Ti–O nanoporous layers are promising as coatings on NiTi stents to prevent re-obstruction after surgery.

Endovascular Double-Layer Bare Stent Placement in the Treatment of Posttraumatic Pseudoaneurysm.

Objective To investigate the efficacy and safety of endovascular double-layer bare stent placement for the treatment of traumatic false aneurysm (TFA). Methods This is a retrospective review of five patients with TFA undergone double-layer bare stent placement in our center between February 2011 and August 2020. There are 2 males and 3 females aged 29-65 years, with an average age of 43 years. One case suffered from common carotid artery pseudoaneurysm, and four cases suffered superficial femoral artery pseudoaneurysm. Results The endovascular interventional treatment was successful in all 5 patients, and the pseudoaneurysms disappeared after treatment. No TFA recurrence and no complications such as instent stenosis, stent migration, stent fracture, endoleak, and infection were observed during the 3-99-month follow-up period. Conclusion For the treatment of TFA, endovascular interventional therapy with double-layer bare stent was minimally invasive, safe, and effective with fewer complications. It could preserve all branches of parent artery and had the advantage of lower cost. It can be used in the treatment of TFA in selected cases. However, further clinical researches with larger cohorts are needed before its long-term efficacy can be completely clarified.

Biodegradable JDBM coating stent has potential to be used in the treatment of benign biliary strictures

In our previous study, to find out the optimal alloy suitable for biliary surgery, magnesium alloy Jiao Da Bio-magnesium (denoted as JDBM) alloy, Zn–3Cu alloys, and their respective coating (MgF2–PDLLA) products were produced for our research. We found that JDBM seems to be a potential material for clinical biliary stent application due to its uniform degradation and good compatibility. In order to apply the JDBM alloy to treat benign bile duct stricture, our group prepared the bare JDBM and its coating product into finished stents by mesh weaving carving technology and conducted the mechanical property tests, degradation tests and biocompatibility tests. During the mechanical property tests, we found the bare JDBM stent was more suitable than titanium alloy stent when applies to the bile duct, and the coating of the JDBM coating stent has no effect on its mechanical properties. Our in vitro and in vivo experiments revealed that the degradation rate of the JDBM coating stent is lower than that of the JDBM stent, and both stents were biosafe. Thus, there is promise for JDBM coating stents for the treatment of benign biliary strictures.

Early outcomes associated with use of the Zenith TX2 Dissection Endovascular Graft for the treatment of Stanford type B aortic dissection

ObjectiveTo evaluate short term outcomes related to the use of the Zenith TX2 Dissection Endovascular Graft (ZDEG) and the Zenith Dissection Bare stent (ZDES) for the treatment of Stanford type B aortic dissections. MethodsThis retrospective multicenter case cohort study collated data from 10 European institutions for patients with both complicated and uncomplicated type B aortic dissection treated with ZDEG and ZDES between 2011 and 2018. The primary end point was mortality at 30 and 90 days. Secondary end points included complications related to TEVAR, such as, type Ia endoleak, stroke, paraparesis, paraplegia, and retrograde type A dissection (RTAD). Statistical analysis was carried out using the t test, or one-way analysis of variance and the χ2 or Fisher exact tests. ResultsWe treated 120 patients (87 male; mean age, 62.7 ± 12.2years) either in the acute 76 (63.3%), subacute 16 (13.3%), or chronic 28 (23.3%) phase. Seven patients (5.8%) died within 30 days after the index procedure and two (1.7%) between 30 and 90 days. There was one instance of postoperative RTAD in a patient treated for rupture. Stroke and paraplegia occurred in three (2.5%) and five (4.2%), patients, respectively. Eight patients (6.7%) had a type Ia endoleak in the perioperative period. There were no instances of paraplegia, no permanent dialysis, and no requirement for adjunctive superior mesenteric or celiac artery stenting in the 33 patients (27.5%) who were treated by concurrent placement of ZDES distal to the ZDEG. The length and distal oversizing of ZDEG components used was less in this group. ConclusionsThe present series demonstrates a low (<1%) RTAD rate and favorable morbidity and mortality. The lower rate of paraplegia, dialysis, and visceral artery stenting in the cohort that had adjunctive use of ZDES is compelling and merits further assessment.

Advances in Preparation and Evaluation of Non-vascular Drug-eluting Stents

In recent years, the application of stent intervention in the treatment of non-vascular stenosis caused by benign and malignant factors has been widely concerned by researchers at home and abroad. The high incidence of malignant tumor diseases, further promotes the development of stent intervention. The conventional bare stents are prone to irritate luminal mucosa and produce restenosis and other complications. The emergence of drug-eluting stent is expected to solve this problem and become one of the important development trends of non-vascular stents. In this paper, the drug loading materials, drug loading layer drugs, preparation technology and quality evaluation methods of non-vascular drugeluting stent are described based on the recent research and clinical application documents, so as to provide basis and direction for the follow-up research and development.

Drug-Coated Balloon versus Bare Nitinol Stent in Femoropopliteal Artery: 12 Months Outcome from a Single Center in China

The study sought to compare the safety and effectiveness of drug-coated balloon (DCB) with bare nitinol stent in patients with complex femoropopliteal(FP) lesions in real-world practice. Patients with symptomatic (Rutherford stage 2 to 5) femoropopliteal lesions who underwent DCB or bare nitinol stent implantation at the Department of Cardiovascular Surgery of China-Japan Friendship Hospital from June 2016 to September 2017 were included. Demographics, angiographic and procedural variables were included. Freedom from target lesion revascularization (TLR), primary patency and major adverse events were obtained from follow-up results at 3,6 and12 months. Descriptive analysis was performed on all variables. A total of 90 eligible patients were enrolled, which included 51 DCB subjects (mean age, 63.1 ± 13.2 years; 76.5% male) with 55 lesions and 39 nitinol stent subjects (mean age, 66.5 ± 10.5 years; 61.5% male) with 42 lesions. Significant higher primary patency was observed in the DCB group compared with the stent group (74.5% vs. 52.4%; log-rank test P = 0.018; HR 0.335, 95%CI 0.124-0.903, P = 0.031). The rates of freedom from TLR (f-TLR) were 78.2% and 59.5% (log-rank test P = 0.032) for the DCB group and the stent group, respectively, at 12 months. CD-TLR rates were 18.2% vs. 38.1% with a P-value of 0.023. Female sex (HR 6.122, 95%CI 1.880-19.934, P = 0.003), lesion length over 20 cm (HR 5.514, 95%CI 2.312-13.148, P < 0.001) and renal insufficiency (HR 2.609, 95%CI 1.087-6.260, P = 0.032) were suggested as independent risk factors of reducing primary patency. There were no significant differences in major adverse events between the 2 groups. The result above demonstrates that DCB treatment has higher primary patency and lower TLR at 12 months than nitinol stent. These data confirm the safety and effectiveness of the DCB for patients with complex femoropopliteal lesions.

Early and midterm outcomes of bare metal stenting in small children with recurrent aortic coarctation.

The aim of this study was to report our experience with the Cook Formula stent in the treatment of (recurrent) coarctation of the aorta in children below 12 kg. In vitro study of the Cook Formula 418 (8 mm) and 535 (8 and 10 mm) stents demonstrated successful down-crimping on smaller balloons and predictable fracturing patterns. Between November 2012 and January 2019, one patient with native, one patient with post-interventional and thirteen patients with post-surgical coarctation of the aorta underwent implantation of a Cook Formula stent. Patient and procedural characteristics were obtained as well as procedural success, complications, and follow-up. Median age was 4.3 months and median weight 5.5 kg. Arterial sheath size ranged from 5 to 7 Fr. In-stent diameters of 3.7 to 8.8 mm were obtained with a median residual gradient of 0 mmHg. Major complications consisted of periprocedural haemodynamic instability (n=1), dissection of the iliac artery (n=1) and non-deployment with surgical removal (n=1). Re-dilations were performed after a median interval of 24.3 months. Median follow-up was 31.7 months. The bare metal Cook Formula stent provides a durable and effective alternative to reoperation and balloon dilatation for native as well as post-surgical aortic coarctation in children below 12 kg.