Absorbable Stents Research Articles

Biodegradable internal biliary stenting in orthotopic liver transplantation – A feasibility study

IntroductionBiliary complications remain a common cause of morbidity after liver transplantation and often require invasive interventions to manage. We aimed to assess the technical feasibility and safety of placement of a biodegradable stent across the biliary anastomosis at the time of liver transplantation in patients having a duct to duct biliary reconstruction. MethodsFor this prospective, single-arm, descriptive study, 10 consecutive patients undergoing whole graft, deceased donor, liver transplantation and duct-to-duct biliary tract reconstruction were enrolled and a biodegradable biliary stent was sutured into the bile duct across the anastomosis. ResultsIn all 10 patients it was technically feasible to place and secure the stent safely during the operation. After >6 months (median of 212 days) follow up, no patients had developed biliary anastomotic stricture. One patient had transient bile leak immediately post-operative that was managed conservatively. One patient required endoscopic intervention for non-anastomotic stricture development and biliary cast material that had resulted in stent dysfunction. DiscussionThe results of this study suggest surgical feasibility of placement of an absorbable biliary stent across the biliary anastomosis at the time of liver transplantation, as well as an acceptable safety profile. Further studies are required to confirm these safety and feasibility findings and to assess efficacy in reducing rates of biliary complications and the need for endoscopic intervention in the early post-transplant period.

Efficacy of Self-Expandable Absorbable Stents during Liver Transplant to Minimize Early Biliary Complications.

We analyzed the use of a self-expandable absorbable biliary stent (SEABS) to reduce biliary complications in liver transplant (LT). Complications related to biliary anastomosis are a still a challenge in LT with a high impact on the patient outcomes and hospital costs. This non-randomized prospective study was conducted between July 2019 and September 2023 in adult LT patients with duct-to-duct biliary anastomoses. The primary endpoint was to assess early biliary complications at 90 days in LT patients with intraoperative SEABS versus no SEABS. We also compared overall biliary complications, costs and SEABS- adverse effects related. A total of 158 patients were included, 78 with SEABS and 80 no-SEABS (22 T-tube and 58 no-stent). There were no adverse effects related to SEABS. Early biliary complications (23.8 vs 2.6%, P <0.001) and hospital stay (19 vs 15 days, P= 0.001) were higher in no-SEABS. No-SEABS group required 63 ERCPs and 13 surgeries (including 2 LT) versus 35 ERCPs and 2 surgeries in SEABS group. After PSM between SEABS (n=58) vs no-SEABS (n=58), early biliary complications (40% vs 0%, P<.001) were higher in no-SEABS group. T-tube had more early biliary complications (22.7% vs 5%, P=0.23) compared SEABS high-risk biliary anastomosis. SEABS excess cost per patient was lower compared to T-Tube and no-stent (6.988€ vs 17.992€ vs 36.364€, P=0.036 and P=0.002, respectively). SEABS during biliary anastomosis in LT is feasible with no adverse effects and avoid the T-tube in high-risk biliary anastomoses. It use has been associated with less early biliary complications, hospital costs and reoperations or interventional treatments for biliary complications resolution.

Absorbable metal stents for vascular use in pediatric cardiology: progress and outlook.

The past five years have yielded impressive advancements in fully absorbable metal stent technology. The desired ultimate ability for such devices to treat a vascular stenosis without long-term device-related complications or impeding future treatment continues to evoke excitement in clinicians and engineers alike. Nowhere is the need for fully absorbable metal stents greater than in patients experiencing vascular anomalies associated with congenital heart disease (CHD). Perhaps not surprisingly, commercially available absorbable metal stents have been implanted in pediatric cardiology patients with conditions ranging from pulmonary artery and vein stenosis to coarctation of the aorta and conduit/shunt reconstructions. Despite frequent short term procedural success, device performance has missed the mark with the commercially available devices not achieving degradation benchmarks for given applications. In this review we first provide a general overview detailing the theory of absorbable metal stents, and then review recent clinical use in CHD patients since the release of current-generation absorbable metal stents around 2019. We also discuss the challenges and our center's experience associated with the use of absorbable metal stents in this pediatric population. Lastly, we present potential directions for future engineering endeavors to mitigate existing challenges.

Bioresorbable scaffolds: past and present. Clinical example of a 10-year follow-up of a patient with an implanted Absorb stent

Bioresorbable scaffolds: past and present. Clinical example of a 10-year follow-up of a patient with an implanted Absorb stent

Bioresorbable Scaffolds for Below-the-Knee Arterial Disease: A Literature Review of New Developments.

This review aimed to explore the therapeutic effect of bioabsorbable stents in the inferior genicular artery, from the emergence of absorbable bare metal stents to the latest technology in polymer and anti-proliferative eluting drugs mixed with coated bioresorbable vascular stents (BVSs). Currently, there are conflicting data regarding the safety and effectiveness of BVSs in infrapopliteal artery interventions, especially compared to the current generation of drug-eluting stents (DESs). This review will cover the existing data on BVSs in reconstructing the infrapopliteal arterial blood flow and active clinical trials for future iterations of BVSs. In terms of primary patency rate and target lesion revascularization rate, the available research on the effectiveness of BVSs in reconstructing the infrapopliteal arterial blood flow suggests that a BVS is compatible with current DESs within 3-12 months; long-term data have not yet been reported. The ABSORB BVS is the most studied BVS in cardiovascular disease (CAD). Initially, the ABSORB BVS showed promising results. Managing intricate regions in peripheral artery disorders, such as branching or lengthy lesions, continues to be a formidable undertaking. In contrast to the advanced narrowing of arteries seen in standard permanent stent procedures, bioabsorbable stents have the potential to promote the expansion and beneficial merging of blood channels in the latter stages. Furthermore, incorporating stents and re-establishing the endothelial function can diminish the probability of restenosis or thrombosis. Nevertheless, the extent to which bioabsorbable stents may simultaneously preserve arterial patency and guarantee their structural integrity remains uncertain. The powerful and intricate mechanical stresses exerted by the blood in the superficial femoral artery and popliteal artery can cause negative consequences on any implant inserted into the vessel, regardless of its composition, even metal. Furthermore, incorporating stents is advantageous for treating persistent occlusive lesions since it does not impact later treatments, including corrective bypass operations. Evidence is scarce about the use of bioabsorbable stents in treating infrapopliteal lesions. Utilizing bioabsorbable stents in minor infrapopliteal lesions can successfully maintain the patency of the blood vessel lumen, whereas balloon angioplasty cannot offer this benefit. The primary focus of testing these materials is determining whether bioabsorbable scaffolds can provide adequate radial force in highly calcified elongated lesions. Indeed, using "-limus" medication elution technology in conjunction with bioabsorbable stents has previously offered clinical benefits in treating the popliteal artery, as evidenced by limited trials.BVSs for peripheral arterial disease (PAD) show promise and have the potential to offer a less inflammatory and more vessel-friendly option compared to permanent metallic stents. However, current evidence does not yet allow for a universal recommendation for their use. Thus, ongoing, and future studies, such as those examining the newer generation of bioresorbable scaffolds (BRSs) with improved mechanical properties and resorption profiles, will be crucial in defining the role of BRSs in managing PAD.

Research on the method of loading exosomes onto absorbable stents

To explore a method of loading exosomes onto absorbable stents. By building a stent-(3-aminopropyl) triethoxysilane-1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol) 5000]-exosomes connection, the exosomes were loaded onto absorbable stents to obtained the exosome-eluting absorbable stents. The surface conditions of the stents and absorption of exosomes were observed by scanning electron microscope and identified through the time-of-flight mass spectrometry; the roughness of the stents' surfaces was observed by atomic force microscope; the appearances and sizes of the stents were observed by stereomicroscope; and the radial force was tested by tensile test machine. The absorbable stents were used as control. The scanning electron microscope observation showed that the exosome-eluting absorbable stents had some small irregular cracks on the surface where many exosomes could be seen. The atomic force microscopy observation showed that within the range of 5 μm 2, the surface roughness of the absorbable stents was ±20 nm, while the surface roughness of the exosome-eluting absorbable stents was ±70 nm. In the results of time-of-flight mass spectrometry, both the exosome-eluting absorbable stents and exosomes had a peak at the mass charge ratio of 81 (m/z 81), while the absorbable stents did not have this peak. The peak of exosome-eluting absorbable stents at m/z 73 showed a significant decrease compared to the absorbable stents. The stereomicroscope observation showed that the sizes of exosome-eluting absorbable stents met standards and the surfaces had no cracks, burrs, or depressions. The radial force results of the exosome-eluting absorbable stents met the strength standards of the original absorbable stent. By applying the chemical connection method, the exosomes successfully loaded onto the absorbable stents. And the sizes and radial forces of this exosome-eluting absorbable stents meet the standards of the original absorbable stents.

Heparin-Loaded Composite Coatings on Porous Stent from Pure Magnesium for Biomedical Applications.

Challenges associated with drug-releasing stents used in percutaneous transluminal coronary angioplasty (PTCA) encompass allergic reactions, prolonged endothelial dysfunction, and delayed stent clotting. Although absorbable stents made from magnesium alloys seem promising, fast in vivo degradation and poor biocompatibility remain major challenges. In this study, zirconia (ZrO2) layers were used as the foundational coat, while calcium phosphate (CaP) served as the surface layer on unalloyed magnesium specimens. Consequently, the corrosion current density was decreased to 3.86, from 13.3 μA/cm2. Moreover, a heparin-controlled release mechanism was created by co-depositing CaP, gelatin (Gel), and heparin (Hep) on the specimens coated with CaP/ZrO2, thereby boosting magnesium's blood compatibility and prolonging the heparin-releasing time. Techniques like X-ray diffractometry (XRD), focused ion beam (FIB) system, toluidine blue testing, UV-visible spectrometry, field emission scanning electron microscopy (FESEM), and surrogate tests for endothelial cell viability were employed to examine the heparin-infused coatings. The drug content rose to 484.19 ± 19.26 μg/cm2 in multi-layered coatings (CaP-Gel-Hep/CaP-Hep/CaP/ZrO2) from 243.56 ± 55.18 μg/cm2 in a single layer (CaP-Hep), with the controlled release spanning beyond 28 days. Also, cellular viability assessments indicated enhanced biocompatibility of the coated samples relative to those without coatings. This suggests the potential of magnesium samples after coating ZrO2 and CaP with Gel as candidates for porous biodegradable stents or even scaffolds in biomedical applications.

Preliminary results of absorbable magnesium stent for treating eustachian tube dysfunction in a porcine model.

Absorbable magnesium (Mg) stents have an attractive biocompatibility and rapid degradation rate, but their degradable behavior and efficacy in the Eustachian tube (ET) have not yet been investigated. In this study, the degradable behavior of the Mg stent in artificial nasal mucus was evaluated. The Mg stents in the porcine ET model were also investigated to evaluate their safety and efficacy. Four Mg stents were placed into the four ETs of two pigs. The mass loss rate of the Mg stents gradually decreased over time. The decrease rates were 30.96% at one week, 49.00% at two weeks, and 71.80% at four weeks. On the basis of histological findings, the thickness of submucosal tissue hyperplasia and the degree of inflammatory cell infiltration significantly decreased at four weeks compared with two weeks. Biodegradation of the Mg stent occurred before tissue proliferative reactions, and the ET patency was successfully maintained without stent-induced tissue hyperplasia at four weeks. The Mg stent that biodegrades rapidly seems to be effective and safe in porcine ET. Further investigation is required to verify the optimal stent shape and indwell period in the ET.

Feasibility and safety of inserting transient biodegradable stents in the pylorus during pylorus-preserving gastrectomy for gastric cancer: a preliminary study in a porcine for proof of concept.

To evaluate whether insertion of self-biodegradable stent into the pylorus to prevent delayed-gastric emptying after pylorus-preserving gastrectomy is feasible and safe through porcine experiment. Self-biodegradable dumbbell-shaped pyloric stents were designed from absorbable suture materials: poly(glycolide-co-caprolactone) (PGCL) or poly-p-dioxanone (PPDO). After gastrotomy on ten pigs, each stent was inserted: two shams, four PGCL stents, and four PPDO stents. Body weight (Bwt), body temperature (BT), complete blood cell (CBC) count, and plain X-ray were evaluated. On postoperative day (POD) 13, euthanasia was performed for histologic evaluation. Operation was successfully performed in all ten pigs. Without tagging suture, both stents migrated before POD 3. The migration was delayed up to POD 13, when the tagging sutures (-t) were applied between stent and stomach wall. Self-degradation of PGCL started from POD 3, and stents were completely excreted from the abdomen by POD 8. Although PPDO were also weakened as self-degradation progressed, its shape was maintained in gastrointestinal tract for 13days. Unexpected sudden death occurred in the pig with PPDO-t2 on POD 10, which is more likely due to acute volvulus rather than stent-related complication. There was no significant difference between three groups in terms of Bwt, BT, CBC, and histology (sham vs. PGCL vs. PPDO, all p > 0.05). The concept of biodegradable stents made of absorbent suture material seems feasible in porcine experiment. Among them, PGCL which has shown rapid absorption, appears to be a more suitable material for transient pyloric absorbable stent when considering safety aspect.

The efficacy and safety of different endovascular modalities for infrapopliteal arteries lesions: A network meta-analysis of randomized controlled trials

Endovascular treatment has become the first-line therapy for infrapopliteal artery occlusive disease (IPOD), while the optimal endovascular method remains to be determined. We performed a network meta-analysis (NWM) of randomized controlled trials (RCTs) to simultaneously compare the outcomes of different endovascular modalities for IPOD. The Pubmed, Embase, and Cochrane databases were used as data sources. The NWM approach used random-effects models based on the frequentist framework. In total, 22 eligible RCTs (44 study arms; 1,348 patients) involving nine endovascular modalities or combinations [balloon angioplasty (BA), drug-coated balloon (DCB), drug-eluting stent (DES), atherectomy device + BA (AD + BA), AD + DCB, balloon-expandable bare metal stent (BMS), self-expanding stent (SES), absorbable metal stents (AMS), and inorganics-coated stent (ICS)] were included. BA had a lower 12-month primary patency rate than DCB (RR 0.50, CI 0.27, 0.93) and AD + DCB (RR 0.34, CI 0.12, 0.93). AD + DCB decreased 6-month TLR compared with AMS (RR 0.15, CI 0.03, 0.90), and DES decreased it compared with BMS (RR 0.25, CI 0.09, 0.71). DCB had a lower 6-month TLR rate than AMS (RR 0.26, CI 0.08, 0.86) and BA (RR 0.51, CI 0.30, 0.89). BA had a higher 12-month TLR rate than DCB (RR 1.76, CI 1.07, 2.90). According to the value of the surface under the cumulative ranking curve (SUCRA), AD + DCB was considered the best treatment in terms of primary patency at 6 months (SUCRA = 87.5) and 12 months (SURCA = 91). AD + BA was considered the best treatment in terms of 6-month TLR (SUCRA = 83.1), 12-month TLR (SURCA = 75.8), and 12-month all-cause mortality (SUCRA = 92.5). In terms of 12-month major amputation, DES was considered the best treatment (SUCRA = 78.6), while AD + DCB was considered the worst treatment (SUCRA = 28.8). Moreover, AD + BA always ranks higher than AD + DCB in the comparison including these two combinations. Subgroup analyses of modalities without stenting did not significantly change the primary outcomes. ADs showed noteworthy advantages in multiple terms for IPOD except for 12-month major amputation. AD + BA may be a better method for IPOD than AD + DCB. The efficacy and safety of ADs are worthy of further investigation. [https://www.crd.york.ac.uk/prospero/], identifier [CRD42022331626].

Computational analysis of designing an improved coronary stents of biodegradable Poly-lactic Acid (PLA)

ABSTRACT The complications arising after the transplantation of conventional stents put atherosclerotic cardiovascular patients at high risk. Biodegradable poly-lactic acid (PLA) stents provide practical solutions for diseased vessels (atherosclerotic) and avoid the side complications of vessels and their incompatibility with permanent stents in the long term. PLA is a biodegradable and reliable material that is used for biodegradable stents designs to maintain natural mechanical behaviour in blood vessels. In this study, we suggest a new cross section ‘circular and elliptic’ that are proposed based on basic square shape cross section to study the mechanical behaviour of stents under pulsatile blood pressure in the blood vessels in order to choose the best shape to allow the biodegradability of Absorb stents with Poly-lactic Acid (PLA) material by numerical fatigue study. Three types of cross-sections stents struts have been analysed to compare their mechanical properties in terms of stress, strain, fatigue damage and life cycle. The numerical results obtained from the finite element analysis (FEA) method demonstrate that the elliptical and circular stents design has better efficiency in terms of stress and strain (16.66–33.33%) and fatigue damage (62.4–86.07%) compared to the square design.

Immediate and Medium-Term (6 Months) Results of BVS Absorb Biodegradable Coronary Scaffolds Installation in Patients with Chronic Forms of Coronary Artery Disease

Aim of study To evaluate the immediate and medium-term (6 months) results of BVS Absorb biodegradable stents implantation in patients with chronic forms of coronary artery disease, taking into account their location in coronary vessels, morphological nature of the initial lesion of the coronary arteries and technical features of implantation as well. Material and methods From June 2014 to December 2015, 199 biodegradable stents (Absorb Bioresorbable Vascular Scaffold — BVS; Abbott Vascular, CA, USA) were routinely installed in 114 patients treated at the Interventional Cardioangiology Center of I.M. Sechenov First Moscow State Medical University. The analysis of the obtained results was carried out depending on the type of coronary artery lesion, the length and diameter of the stents, and the details of the angioplasty procedure. To characterize the type of coronary artery lesion, the ACC/AHA classification was used: type A vascular lesion (95 coronary segments); type B vascular disease (68 coronary segments); type C vascular disease (36 coronary segments). The ultimate goal of the study was to study the frequency of thrombosis and in-stent stenosis of stented coronary arteries. Results The immediate success of scaffold implantation was 98.2%. Complications in the early hospital period were 1.8% (acute stent thrombosis was observed in 2 cases on the first day after implantation). In the medium-term (~6 months), 102 patients (89.5%) with 172 previously placed stents underwent comparison selective coronary angiography. The rest of the patients with stents refused to undergo coronary angiography due to good health and underwent a telephone survey. The satisfactory result of stenting in the medium-term (6 months) was a completely preserved lumen of the stented area, or with less than 50% stenosis of this place, which comprised 94.3%. The frequency of in-stent stenosis (narrowing of the lumen of the stented area by 50% or more) was 5.7%. In-stent stenosis was detected in groups of patients with type B and C lesions, respectively, in 4% and 1.7%. In the group with type A coronary artery disease, in-stent stenosis was not detected in the medium-term period. Conclusion The immediate and medium-term results of stenting with the biodegradable BVS Absorb stent were successful in the vast majority of cases (94.3%). Only in 2 cases (1.8%), acute thrombosis of the stent was observed immediately after stenting.

Microstructure refinement in biodegradable Zn-Cu-Ca alloy for enhanced mechanical properties, degradation homogeneity, and strength retention in simulated physiological condition

• The first application of ultrasonic treatment (UST) for microstructure refinement in biodegradable Zn alloy. • UST processing eliminated the cracked and segregated CaZn 13 phase in Zn-Cu-Ca alloy after hot rolling. • The UST-processed Zn-Cu-Ca alloy indicated improved mechanical properties. • The corrosion of UST-Zn-Cu-Ca alloy is more uniform than the non-UST counterpart under the similar corrosion rate. • The uniform degradation mechanism favour the strength retention of UST-Zn-Cu-Ca alloy in vitro . Zn-1.0Cu-0.5Ca (TA15) alloy has shown promising characteristics of enhanced mechanical properties and biodegradability for absorbable cardiovascular stents, endovascular devices, and wound closure devices applications. In this study, the TA15 alloy for bioabsorbable biomedical applications is investigated. In the conventionally cast TA15 (TA15-C) alloy, CaZn 13 phase are present as a large dendritic network with an average size of 73.25 ± 112.84 μm. Hot rolling of the TA15-C alloy has broken the long and dendritic network of the CaZn13 phases, however, the refined phases are observed as segregations and the distribution is non-uniform. These segregated CaZn 13 suffered heavy localised corrosion which lead to poor mechanical properties in the as-fabricated condition and after biodegradation. Ultrasonic treatment (UST) during casting is identified as an effective technique for the refinement and redistribution of CaZn 13 particles in TA15 alloy, which successfully reduce the size of the CaZn 13 phase to 10.91 ± 4.65 μm in the as-solidified condition. After hot rolling, the UST processed TA15 (TA15-UST) shows improved mechanical properties due to grain refinement and the reduction in microstructural defects, i.e. the broken CaZn 13 phase. Results of 8-week immersion corrosion tests showed that both alloys possess very similar corrosion rate. However, TA15-UST has markedly improved corrosion homogeneity compared to TA15-N which favours the retention of mechanical properties even after prolonged exposure to physiological fluids.

Short-term postoperative efficacy of steroid-eluting stents for eosinophilic chronic rhinosinusitis with nasal polyps: A randomized clinical trial.

Eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) is a refractory clinical phenotype with a high symptom burden and relapse rate. Steroid-eluting stents are safe and effective for reducing polyp size, symptom burden, and the need for revision sinus surgery. In this study we aimed to evaluate the efficacy and safety of steroid-eluting stent implantation on the surgical outcomes of patients with ECRSwNP. This prospective, multicenter, randomized, intrapatient-controlled trial recruited patients 18 to 65 years of age with ECRSwNP who required surgery. Ninety-eight patients were enrolled and randomly implanted with absorbable steroid-eluting stents containing mometasone furoate in one sinus at the end of surgery. All patients received standard postoperative care and follow-up. The primary outcome was the Lund-Kennedy endoscopic score within 12weeks postsurgery. Secondary outcomes included nasal symptoms scores, nasal resistance, acoustic rhinometry, nasal nitric oxide levels, 3-dimensional volumetric computed tomography scores, and eosinophil counts in the ethmoid mucosa. Ninety-five patients completed the trial. At postoperative weeks 4, 8, and 12, the Lund-Kennedy scores were significantly lower on the treatment side than on the control side (all p<0.01). Compared with the treatment side, the control side exhibited higher tissue eosinophilia at week 4 and higher volumetric, nasal obstruction, and total nasal symptom scores at postoperative week 8 (p=0.011, p=0.011, p<0.01, and p=0.001, respectively). No adrenal cortical suppression or serious side effects were observed. Steroid-eluting stents reduce postoperative sinus mucosal edema, and eosinophilic inflammation, with persistent effects after stent disintegration, and are a good supplementary postsurgical treatment in patients with ECRSwNP.

A hydrophobic layer prepared by cyclic grafting of polydimethylsiloxane on magnesium: improved corrosion resistance and biocompatibility.

Magnesium and its alloys have been widely studied as absorbable coronary stent materials. However, the rapid corrosion rate in the intravascular environment inhibits the application of magnesium-based stents. In order to endow magnesium-based stent with appropriate degradation rate and biocompatibility, a hydrophobic layer was constructed by in situ cyclic grafting 4,4′-diphenylmethane diisocyanate and aminopropyl-terminated polydimethylsiloxane on pure magnesium. SEM-EDS, X-ray photoelectron spectroscopy and water contact angle were detected to analyze the chemical composition of the layer. The amino groups were confirmed to be introduced on the surface which provide a platform for subsequent modification. The contact angle value of the modified surface is 132.1°, indicating a hydrophilic surface. The electrochemical measurements and immersion tests demonstrated that the hydrophobic layer significantly improved the anti-corrosion ability of the substrate. Besides, the biocompatibility of the hydrophobic surface was examined by platelet adhesion, cytocompatibility in vitro and subcutaneous implantation in vivo. Immunological and histological results indicated that the hydrophobic layer had excellent biocompatibility. Therefore, the presented study might be a promising method for the surface modification of biomedical magnesium-based stent.

Archimedes® Absorbable Internal Biliary Stent in Liver Transplants to Prevent Bile Leak

Introduction: Biliary complications, especially bile leaks are an important cause of early post-operative morbidity and rarely mortality after liver transplant. The risk is higher in living donor liver transplant (LDLT) compared to deceased donor liver transplant (DDLT) because of many well-known factors. Attempts to reduce bile leaks have included improvements in graft retrieval, refinements in the biliary anastomosis technique and use of various external and internal stents with inconsistent benefits. Recent availability and successful use of the absorbable Archimedes® stent has prompted its intra-biliary placement across the anastomosis. Methods: In this retrospective study, we analyzed data of 20 adult patients who underwent liver transplantion from December 2019 to January 2020 with duct-to-duct biliary anastomosis (DDA) using Archimedes® stent.. Liver Transplantion was performed using cava-preserving hepatectomy followed by standard implantation methods. Duct-to-duct (DDA) biliary anastomosis was performed using interrupted polydioxanone sutures with extracorporeal knots over an absorbable intra-biliary stent. Results: Nine DDLT had a single anastomosis over a 10Fr stent. Out of 11 LDLT patients, 7 had a single anastomosis and 4 patients had two anastomosis, all over a 6Fr stent. Two patients died due to graft primary non-function and multi-drug resistant pneumonia respectively. One patient had ascending cholangitis due to stent migration and was managed with endoscopic stent removal and appropriate antibiotics. None of the other patients had bile leak, bilioma, stent related complications or required any endoscopic or radiological procedure. Conclusions: Archimedes® internal absorbable biliary stents can be safely used in both LDLT and DDLT to prevent bile leaks.

Archimedes Absorbable Internal Biliary Stent in Liver Transplants to Prevent Bile Leak

Biliary complications, especially bile leaks, are an important cause of early postoperative morbidity and, rarely, mortality after liver transplant. The risk is higher in living donor liver transplant (LDLT) compared to deceased donor liver transplant (DDLT). Attempts to reduce bile leaks have included refinements in the biliary anastomosis technique and use of various external and internal stents, with inconsistent benefits. Recent availability and successful use of the absorbable Archimedes stent has prompted its intrabiliary placement across the anastomosis. In this retrospective study, we analyzed the data of 20 adult patients who underwent a liver transplant with duct-to-duct biliary anastomosis using the Archimedes stent. Both DDLT and LDLT were performed using cava-preserving hepatectomy followed by standard implantation methods. Duct-to-duct biliary anastomosis was performed in all cases using interrupted sutures with extracorporeal knots over an absorbable intrabiliary stent. In addition to standard postoperative care, patients were monitored for bile leak. Nine DDLTs had a single anastomosis over a 10-Fr stent. Out of 11 LDLT patients, 7 had a single anastomosis and 4 patients had 2 anastomoses, all over a 6-Fr stent. Two patients died, 1 as a result of graft primary nonfunction and another because of multidrug-resistant pneumonia. One patient had ascending cholangitis owing to stent migration in the duodenum. This episode was treated with endoscopic stent removal and appropriate antibiotics, with good recovery. None of the other patients had bile leaks, biloma, or stent-related complications. Archimedes internal absorbable biliary stents can be safely used in both living and deceased donor liver transplants to prevent bile leaks.

Numerical design studies of meander structures for self-expanding absorbable stents

Abstract Absorbable stents made of poly-L-lactic acid (PLLA) exhibit inferior mechanical properties compared with metal based devices. Therefore, design optimization by means of finite element analysis (FEA) plays an important role in development of high performance absorbable stents. In the present study, three different meander structures made of PLLA material were compared in terms of their radial resistive force (RRF) using FEA. Material tests were performed to obtain input parameters of PLLA for the simulation. FEA was carried out to simulate the RRF and the length change of the meander structures as a function of the diameter. In addition, the numerical results were compared to the experimental outcome using corresponding meander based stents performing radial testing with a segmented head mechanism. Comparable high stresses occurred in the Ubends of the examined stent designs. In designs with a large radius of curvature less stress was observed while crimping. One meander structure developed comparatively higher structural resistance against radially acting forces, due to its curved strut design. In general, FEA revealed consistent results compared to the experimental investigations.

Five-year outcomes of implantation of Absorb biodegradable stents using the bifurcation stenting technique: a case report

The presented case report describes a five-year outcomes of bifurcation stenting of the left anterior descending artery and large diagonal branch with Absorb bioabsorbable vascular stent (BVS) according to selective coronary angiography and optical coherence tomography. The example demonstrates not only the successful implantation of biodegradable stents into the bifurcation area, but also the complete restoration of the arterial wall with the formation of neocarina. Optical coherence tomography made it possible to study in detail all stages of vascular wall alterations from the inside. This case report prompts a fresh look at the biodegradable BVS Absorb stents and does not rule out the potential of returning these stents to clinical practice in the future. Currently, the production and use of Absorb BVSs has been suspended, but they have filled a certain niche in the endovascular treatment of patients with coronary artery disease.

Tailor-made shape memory stents for therapeutic enzymes: A novel approach to enhance enzyme performance

Herein, our suggestion is to immobilize enzymes in-situ on absorbable shape-memory stents instead of injecting therapeutic enzymes into the blood. Chitosan (CHI)-based stents were tailored as novel support and the enzyme-immobilizing ability was elucidated using L-asparaginase (L-ASNase). For developing shape-memory stents, CHI-glycerol (GLY) solution was prepared and further blended with different ratios of polyethylene glycol (PEG), and polyvinyl alcohol (PVA). Afterward, the blends were modified by ionic crosslinking with sodium tripolyphosphate to obtain a shape-memory character. L-ASNase was included in the blends by using in-situ method before ionic crosslinking. The prepared stents, with or without L-ASNase, were comprehensively characterized by using several techniques. Collectively, immobilized L-ASNase exhibited much better performance in immobilization parameters than free one, thanks to its improved stability and reusability. For instance, CHI/GLY/PEG-3@L-ASNase retained about 70% of the initial activity after storage at 30 °C for 2 weeks, whereas the free form lost half of its initial activity. Besides, it retained 73.4% residual activity after 15 consecutive cycles. Most importantly, stent formulations exhibited ~60% activity in the bioreactor system after 4 weeks of incubation. Given the above results, shape-memory stents can be a promising candidate as a new platform for immobilization, especially in the blood circulation system.