Control Stents Research Articles

In vivo biocompatibility of a new hydrophobic coated Al/Al2O3 nanowire surface on stents

BackgroundIntima proliferation and in-stent restenosis is a challenging situation in interventional treatment of small vessel obstruction. Al/Al2O3 nanowires have been shown to accelerate vascular endothelial cell proliferation and migration in vitro, while suppressing vascular smooth muscle cell growth. Moreover, surface modification of Al/Al2O3 nanowires with poly[bis(2,2,2-trifluoromethoxy)phosphazene (PTFEP) coating enables further advantages such as reduced platelet adhesion. Therefore, the study's goal was to compare the biocompatibility of novel Al/Al2O3 + PTFEP coated nanowire bare-metal stents to uncoated control stents in vivo using optical coherence tomography (OCT), quantitative angiography and histomorphometric assessment. Methods15 Al/Al2O3 + PTFEP coated and 19 control stents were implanted in the cervical arteries of 9 Aachen minipigs. After 90 days, in-stent stenosis, thrombogenicity, and inflammatory response were assessed. Scanning electron microscopy was used to analyse the stent surface. ResultsOCT analysis revealed that neointimal proliferation in Al/Al2O3 + PTFEP coated stents was significantly reduced compared to control stents. The neointimal area was 1.16 ± 0.77 mm2 in Al/Al2O3 + PTFEP coated stents vs. 1.98 ± 1.04 mm2 in control stents (p = 0.004), and the neointimal thickness was 0.28 ± 0.20 vs. 0.47 ± 0.10 (p = 0.003). Quantitative angiography showed a tendency to less neointimal growth in coated stents. Histomorphometry showed no significant difference between the two groups and revealed an apparent inflammatory reaction surrounding the stent struts. ConclusionsAt long-term follow-up, Al/Al2O3 + PTFEP coated stents placed in peripheral arteries demonstrated good tolerance with no treatment-associated vascular obstruction and reduced in-stent restenosis in OCT. These preliminary in vivo findings indicate that Al/Al2O3 + PTFEP coated nanowire stents may have translational potential to be used for the prevention of in-stent restenosis.

A self calibrating, magnetic sensor approach accurately positions an aortic damage control stent in a porcine model

ObjectivesNon-compressible torso hemorrhage remains a high mortality injury, with difficulty mobilizing resources before exsanguination. Previous studies reported on a retrievable stent graft for damage control and morphometric algorithms for rapid...

Evaluation of Femoropopliteal In-Stent Restenosis Characteristics Stratified by Stent Design

Purpose: To evaluate the potential differences in characteristics of femoropopliteal in-stent restenosis (ISR) stratified by stent design with a focus on the swirling flow-inducing BioMimics 3D helical centerline stent. Methods: Patients with ISR of the superficial femoral and popliteal arteries undergoing reintervention were included in this study. The primary endpoint was the angiographic localization and extent of restenosis or reocclusion with the following five different stent systems: SMART Control stent, Supera peripheral stent, GORE® VIABAHN® endoprosthesis, BioMimics 3D stent, and Zilver® PTX® stent. Results: 414 ISR lesions were analyzed, affecting 236 Supera stents, 67 BioMimics 3D stents, 48 Zilver® PTX® stents, 38 SMART Control stents, and 25 VIABAHN® endoprostheses. The mean stent diameter and length were 5.7 ± 0.77 mm and 121.4 ± 94.8 mm, respectively. ISR included 310 (74.9%) lesions with 1 stent, 89 (21.5%) lesions with 2 stents, 14 (3.4%) lesions with 3 stents, and 1 lesion (0.2%) with 4 stents. Most lesions presented as reocclusions (67.4%) rather than focal (13.3%) or diffuse restenoses (19.3%). No significant differences in ISR lesion morphology were found. By trend, BioMimics 3D stent lesion extension was more focal (16.4% versus 12.7%, p = 0.258), with the highest proportion of lesions in which only the proximal stent third was affected (9.0% versus 5.8%, p = 0.230), as compared to the average of the other four devices. The occlusion rate was the second lowest for the BioMimics 3D stent (64.2 vs. 68.0%, p = 0.316). Risk factors for restenosis or occlusion were active smoking, pre-interventional occlusion, and popliteal intervention. Conclusion: Our results suggest that the helical centerline stent design of the BioMimics 3D stent, which results in a swirling flow with increased wall shear stress, may offer protective properties over straight stent designs, including DES and endoprosthesis, regarding localization and extension of restenosis. Prospective, randomized studies are warranted.

In silico fatigue optimization of TAVR stent designs with physiological motion in a beating heart model

Background and ObjectiveThe rapid expansion of TAVR to younger, low-risk patients raises concerns regarding device durability. Necessarily, extended stent lifetime will become more critical for new generation devices. In vitro methods commonly used for TAVR stent fatigue testing exclude the effects of the beating heart. We present a more realistic in silico stent fatigue analysis utilizing a beating heart model in which TAVR stents experience complex, nonuniform dynamic loading. MethodsVirtual TAVR deployments were simulated in the SIMULIA Living Heart Human Model of a beating heart using stent models of the self-expandable nitinol 26-mm CoreValve and Evolut R devices, and a 27-mm PolyV-2. Stent deformation was monitored over three cardiac cycles, and fatigue resistance was evaluated for the nitinol stents using finite element analysis via ABAQUS/Explicit. The average strain and strain amplitude of each stent element were tracked, and established thresholds were applied to determine potential fatigue failure. Fatigue performance of control stents was compared to parametrically modified models with a 20% increase or decrease in strut width. ResultsStents with reduced strut width applied lower radial force against the contracting myocardium of the beating heart, resulting in larger displacements and higher strain values. Formulas relating in vivo strain to stent design do not account for this. In all models, there were elements in which strains exceeded fatigue failure. The PolyV-2 stent had far fewer failing elements since its struts were optimized to reduce the strain in stent joints, achieving better fatigue resistance in the stent crown and waist elements. Different stent sections showed markedly different fatigue resistance due to the varying loading conditions. ConclusionsOur analysis indicates that previous studies underestimate strain amplitudes that may cause stent failure. This study demonstrates the utility of advanced in silico analysis of devices deployed within a beating heart that mimics in vivo loading, offering a cost-effective alternative to human or animal trials and establishing a platform to assess the impact of device design on device durability. The limited fatigue life of TAVR stents indicated here highlights a clinical complication that may eventually develop as younger, lower-risk TAVR patients, age.

A novel noble metal stent coating reduces in vitro platelet activation and acute in vivo thrombosis formation: a blinded study

Inherent to any stenting procedure is the prescription of dual antiplatelet therapy (DAPT) to reduce the platelet response. Clinical guidelines recommend 6–12 months of DAPT, depending on stent type, clinical picture and patient factors. Our hypothesis is that a nanostructured noble metal coating has the potential to reduce protein deposition and platelet activation. These effects would reduce subsequent thrombo-inflammatory reactions, potentially mitigating the need for an extensive DAPT in the acute phase. Here, a noble metal nanostructure coating on stents is investigated. Twelve pigs underwent endovascular implantation of coated and non-coated stents for paired comparisons in a blinded study design. The non-coated control stent was placed at the contralateral corresponding artery. Volumetric analysis of angiographic data, performed by a treatment blinded assessor, demonstrated a significant thrombus reduction for one of the coatings compared to control. This effect was already seen one hour after implantation. This finding was supported by in vitro data showing a significant reduction of coagulation activation in the coated group. This novel coating shows promise as an implant material addition and could potentially decrease the need for DAPT in the early phases of stent implementation.

305 Enhancing Endothelialization of Flow Diverting Stents: An In Vitro Study

INTRODUCTION: Flow diverting (FD) stents revolutionized the management of broad neck aneurysms. Several FD stents surface modifications have been developed over the last decade to reduce thromboembolic complications or enhance aneurysmal occlusion rates. Promoting FD endothelization through surface coating has emerged as a novel modality to enhance stent coverage, thus improving aneurysmal occlusion, reducing aneurysmal progression and post-treatment failure. Herein, we report our in vitro experience with FD surface modification using gelatin. METHODS: PED Flex stents were incubated overnight with either PBS (unmodified) or gelatin, followed by a three-hour incubation with human microvascular endothelial cells. Endothelial cell attachment and proliferation were assessed at various time points. RESULTS: There was a significant increase(p < 0.05) in endothelial cell attachment on gelatin(6.3 ± 2.1)surface modified stents compared to unmodified control stents. This increase in endothelial cells was maintained 14 days gelatin 6.3 ± 2.7, fold of control)following cell incubation but gradually decreased until it became insignificant by day 21. Next, we analyzed the temporal rate of endothelial stent coverage. Following cell incubation, 20% of surface-modified stents were coated by endothelial cells on day 5 compared to just 2% in unmodified stents. This difference in cell coverage remained significant (p < 0.05), with surface-modified stents being entirely covered by 2 weeks while unmodified stents were only 50% covered. We also observed a significant increase (p < 0.05, fold of unmodified) in endothelial cell migration onto (1.8 ± 0.2) and from (1.5 ± 0.033) gelatin-coated stents compared to unmodified controls. CONCLUSIONS: Our in vitro experience demonstrates that gelatin has the potential to enhance the endothelialization of FD, leading to increased aneurysm occlusion rates, thereby minimizing post-treatment failure. Further investigations are essential to fully evaluate this novel modality and compare it to the commercially available devices.

SURGICAL TREATMENT OF EARLY POSTOPERATIVE COMPLICATIONS OF ENDOVASCULAR REVASCULARIZATION OF A MULTI-LEVEL STENOTIC-OCCLUSIVE ATHEROSCLEROTIC LESION OF THE FEMORAL-DISTAL ARTERIAL BED

The use of endovascular techniques remains the only chance to restore blood flow under the conditions of a distal stenotic-occlusive process. Nevertheless, under the conditions of endovascular reconstructive surgery of the distal arterial bed, unsatisfactory results occur in 6-32% of cases in the form of thrombosis or restenosis of the reconstruction segment due to the progression of signs of limb ischemia.
 The aim is to improve the results of endovascular revascularization of multilevel atherosclerotic stenotic-occlusive femoral-distal arterial bed by surgical treatment of postoperative complicated forms of revascularized infrainguinal arterial bed.
 Materials and methods. 164 patients with multilevel stenotic-occlusive lesions of the femoral-distal arterial bed were under observation. Ultrasound dopplerography was used to select the volume of reconstructive intervention. Endovascular angioplasty of the femoral-popliteal segment (I stage) was performed with Pan Medical (PEKICO), OPTA PRO (Cordis) balloon catheters. In 41.10% of observations, balloon angioplasty of the femoral segment was continued with the placement of a stent - a self-expanding Smart ControL stent (Cordis), a self-expanding Carbostent stent (Flype), a self-expanding stent - Vascular stent (BARD) was used. Endovascular angioplasty of the arteries of the tibial segment (II stage) was performed using long balloons (80-150 mm) Armada 35 LL manufactured by Abbott Vascular (USA) and Amphirion Deep (Medtronic) Coyote (Boston Scientific). 76 intraluminal and 33 subintimal angioplasty were performed. When performing subintimal angioplasty, CompleteSE (Medtronic), Smart (Cordis) and CompleteSE (Medtronic) stents were used. In 40 patients, angioplasty was performed on two arteries of the leg, in 33 - on one of the tibial arteries. At the first stage, an open reconstruction of the femoral-popliteal segment was performed - the formation of a femoral-popliteal autovenous shunt. In 20 (21.98%) observations, the proximal anastomosis was formed at the level of the bifurcation of the thoracic cavity during simultaneous deep fundoplasty. In 36 (39.51%) observations, the distal anastomosis of the autovenous shunt was formed at the level of the PCA by the end-to-end type. A 6F Check-Flo Performer (USA), Balton (EU) introducer was used to ensure the change of the balloon catheter. Long balloons (80-150 mm) Armada 35 LL manufactured by Abbott Vascular (USA) and Amphirion Deep (Medtronic) Coyote (Boston Scientific) were used, CompleteSE stents (Medtronic) – 23 cases, Smart (Cordis) – 24 observations.
 Conclusions. The early postoperative period of endovascular revascularization of a multilevel stenotic-occlusive lesion of the femoral-distal arterial bed is complicated by thrombosis of the popliteal-tibial segment in 15.9% of observations. Thrombosis of the popliteal segment is detected 2.7 times more often after endovascular angioplasty of one of the tibial arteries during endovascular revascularization of a multilevel stenotic-occlusive lesion of the femoral-distal arterial bed than during endovascular angioplasty of two tibial arteries. The effectiveness of the use of rheological thrombus extraction by the Angiojet system in the surgical treatment of postoperative thrombosis of the popliteal segment, which is formed in 15.9% of observations after endovascular revascularization of a stenotic-occlusive lesion of the femoral-distal arterial bed, is equal to 84.6%.

ASSESSMENT OF VASCULAR RESPONSE OF N-DEAVOUR® DRUG ELUTING STENT VS. XIENCE PRO™ DRUG ELUTING STENT AND MULTILINK VISION BARE METAL STENT IN THE PORCINE CORONARY ARTERY MODEL

Objectives: The objectives of the study were to evaluate the vascular and tissue response of Pakistani manufactured novel drug eluting stent (called N-DEAVOUR®) on a swine model and compare the results with XIENCE PRO™. Methodology: A total of 10 animals were used for the study and assigned randomly to each time-point group. The test articles were administered percutaneously and each animal was implanted with one stent in each one of the coronary arteries (3 in total) LCA (left circumflex artery), LAD (left anterior descending coronary artery), and RCA (right coronary artery). Additionally, a second test stent was implanted in some animals (4 in total). QCA (Quantitative Coronary Angiography) technique was used for measurements of the vessel at the target site. OCT (Optical Coherence Tomography) was performed only at follow up time-points which were 30, 90 and 180 days. Results: At 30 DFU, parameters for N-DEAVOUR® were comparable to those of both control (XIENCE PROTM and VISION) stents. At 90 days follow-up N-DEAVOUR® showed no statistically significant difference in performance for values of lumen area, stent area, area stenosis, and neointimal area against XIENCE PRO™. With reference to stent area, at 90 DFU, N-DEAVOUR® performed better than XIENCE PRO™ (p=0.0056). For neo-intimal area, area stenosis and lumen area, the differences between XIENCE PRO™ and N-DEAVOUR® were non-significant (p=0.13; p=0.9; p=0.086) respectively. These results indicate the positive potential of N-DEAVOUR® to be successfully implanted in clinical settings after necessary randomized clinical trials are executed. Conclusion: This study proved that the drug eluting stent examined in the present study is both safe and feasible. This study supports that this stent can move forward for human trials.

Accurate Stent Placement in Challenging Percutaneous Coronary Interventions Using the Stent Positioning Assist System

ObjectiveTo evaluate safety and accuracy of stent placement by Stent Positioning Assistance System (SPAS), an innovative device that allows for mm-precise manipulation and placement of stents in percutaneous coronary interventions (PCI). BackgroundIn PCI, controlled stent manipulation and precise stent placement remain compromised despite developments in stents and imaging. MethodsSixty-seven patients with various lesion types that required precise stenting were included in this study. All patients were treated with the support of SPAS. Safety was evaluated by looking at procedural success, occurrence of intraprocedural complications and incidence of (device related) adverse events. In subsets of procedures, usability feedback was collected and stent positioning accuracy was assessed with intravascular imaging. ResultsIn 67 patients, 84 stents were implanted by 5 operators. Intravascular Ultrasound (IVUS, n = 6) and Optical Coherence Tomography (OCT, n = 15) was used to assess stent position after placement. Using SPAS, procedural success was achieved in all 67 (100%) cases. There were no intraprocedural complications nor any adverse events. In most procedures, SPAS provided significant support to the operator and the positive procedure impact was rated as major. OCT results showed accurate stent placement with a positioning error of <1 mm (n = 11), 1–2 mm (n = 2) and 3 mm (n = 1) relative to predefined targets; generally the ostium of a side branch or of the coronary artery, and a stent overlap of 1-3 mm in 5 stent-to-stent situations. ConclusionSPAS is safe and allows for enhanced control and accurate stent placement in different types of PCI procedures without impairing procedural workflow.

The Supera Interwoven Nitinol Stent as a Flow Diverting Device in Popliteal Aneurysms

PurposeThe feasibility of using a compressed interwoven Supera stent as a flow diverting device for popliteal aneurysms was recently demonstrated in patients. It is unclear, however, what the optimal flow diverting strategy is, because of the fusiform shape of popliteal aneurysms and their exposure to triphasic flow. To assess this flow diverting strategy for popliteal aneurysms, flow profiles and thrombus formation likelihood were investigated in popliteal aneurysm models.Materials and MethodsSix popliteal aneurysm models were created and integrated into a pulsatile flow set-up. These models covered a bent and a straight anatomy in three configurations: control, single-lined and dual-lined Supera stents. Two-dimensional flow velocities were visualized by laser particle image velocimetry. In addition, the efficacy of the stent configurations for promoting aneurysm thrombosis was assessed by simulations of residence time and platelet activation.ResultsOn average for the two anatomies, the Supera stent led to a twofold reduction of velocities in the aneurysm for single-lined stents, and a fourfold reduction for dual-lined stents. Forward flow was optimally diverted, whereas backward flow was generally deflected into the aneurysm. The dual-lined configuration led to residence times of 15–20 s, compared to 5–15 s for the single stent configurations. Platelet activation potential was not increased by the flow diverting stents.ConclusionA compressed Supera stent was successfully able to divert flow in a popliteal aneurysm phantom. A dual-lined configuration demonstrated superior hemodynamic characteristics compared to its single-lined counterpart.

An assessment of magnesium AZ31 coronary stents manufacture

AZ31 magnesium coronary stents were studied through a manufacturing process chain involving laser cutting, acid pickling, and dip coating. The purpose of this study was to evaluate surface thickness and geometrical dimensions of stents after processing. Stents were dip coated in a solution using PCL with 1% of TiO2. Additionally, AZ31 coronary stents were dynamically tested using a degradation system based on peristaltic pumps. Our results indicate that coated stents degraded slower than AZ31 uncoated control stents. After 4 weeks of dynamic degradation under flowing Hank’s solution, coated stents lost only ∼9% in weight while uncoated stents lost ∼27% in weight. Stents were qualitatively evaluated after four weeks of degradation. Our results demonstrate the formation of micro-pores after one and two weeks of degradation for coated stents. Lamination was observed after three weeks of degradation, meanwhile, uncoated stents resulted with notches and an irregular surface caused by degradation.

Comparison of stent and indomethacin suppository efficacy in the prevention of acute pancreatitis after ERCP.

Objective:We aimed to compare stent and indomethacin suppository efficacy in the prevention of acute pancreatitis after ERCP.Materials and Methods:76 high-risk patients undergoing ERCP were included in the study. The patients were divided into three groups as indomethacin group, stent group and control group. Indomethacin group (n = 32) received 100 mg rectal indomethacin immediately after ERCP. A 5F pancreatic stent was applied to the stent group (n = 16) during ERCP. No prophylaxis was given to the control group (n = 28).Results:There was no difference between the groups in terms of age and gender. ERCP pancreatitis was seen in 9.2% (7/76) of the patients. The incidence of ERCP-induced pancreatitis (PEP) was 3.1% (1/32) in the indomethacin group and 21.4% (6/28) in the control group. PEP was not seen in the stent group (0/16). The incidence of PEP was significantly lower in the indomethacin group than in the control group (p = 0.043). However, no significant difference was found between the stent and control groups, stent and indomethacin groups in terms of PEP frequency (p = 0.072, p: 0.90 respectively).Conclusion:According to the results of our study, rectal indomethacin administration decreased the frequency of PEP in high-risk patients. However, there was no significant difference in PEP prophylaxis between the stent and indomethacin groups.

An Innovative Customized Stent Graft Manufacture System Assisted by Three-Dimensional Printing Technology

Commercially available thoracic aortic stent grafts rarely match the geometric characteristics of the aorta perfectly, which can lead to complications. Customization maybe a solution for this problem, but the delay inherent in the current manufacturing process makes it unable to meet the urgent requirement of acute aortic events. We established and optimized a rapid design and manufacture system for a customized aortic stent graft assisted by 3-dimensional (3D) printing technology. We also evaluated the preliminary feasibility and capability of this customized stent graft. Seven essential production steps comprised the rapid design and manufacture process for the customized stent graft system assisted by 3D printing technology. Optimization of the manufacture process was refined over time in 3 stages. Bench test and invivo experiments were used to verify the feasibility of this system and evaluate the preliminary usability of the customized stent graft. After optimization, the theoretical production time of the customized stent graft was reduced to approximately 12 hours. Bench test showed radial forces against the aorta wall were better distributed in the customized stent graft than in the control stent graft. Invivo experimental results showed that the customized stent graft system worked effectively. It was feasible to rapidly design and manufacture a customized aortic stent graft assisted by 3D printing technology, which demonstrated better geometric compliance and physical characters in the bench test and in invivo experimentation. The manufacturing process could be accelerated to approximately 12 hours, which might be optimized further to meet urgent clinic requirements.

PERFORMANCE TEST AND EXPERIMENTAL STUDY OF SPECIAL STENT FOR TREATMENT OF ILIAC VEIN STENOSIS

Objective: Animal experiments and clinical trials were carried out to evaluate the efficiency of a new stent for the treatment of iliac vein stenosis. Methods: The new iliac vein stent and the control stent were implanted, respectively, into the 12 experimental pigs. Digital Subtraction Angiography was done separately at the same day, 14th, 30th, 60th and 90th day after stent implantation to observe the stent deployment. One patient was implanted with a new iliac vein stent. Digital subtraction angiography (DSA) was done after the operation to calculate the lumen loss value and lumen loss rate of the stent and evaluate the performance of the new iliac vein stent at 12 months of follow-up. Results: The mechanical experiment and finite element analysis of the stent proved that the radial support force of the new stent is significantly better than that of the control stent. In animal experimental verification, both groups of stent were released satisfactorily during implantation. No obvious stent displacement was found at each time point. The patency rate of stents was 100%. Except for a small amount of old thrombosis in the stent in the control group, no other stents were found in that condition. The diameter of the stent lumen was retracted in different degrees in both groups after the operation, but no significant statistical difference was found in the comparison of the stent lumen loss rate at each relative inspection day. Conclusion: The new nickel-titanium alloy iliac vein stent has excellent radial support performance, which may be an ideal iliac vein stent.

Kv1.3 blockade inhibits proliferation of vascular smooth muscle cells in vitro and intimal hyperplasia in vivo

The modulation of voltage-gated K+ (Kv) channels, involved in cell proliferation, arises as a potential therapeutic approach for the prevention of intimal hyperplasia present in in-stent restenosis (ISR) and allograft vasculopathy (AV). We studied the effect of PAP-1, a selective blocker of Kv1.3 channels, on development of intimal hyperplasia in vitro and in vivo in 2 porcine models of vascular injury. In vitro phenotypic modulation of VSMCs was associated to an increased functional expression of Kv1.3 channels, and only selective Kv1.3 channel blockers were able to inhibit porcine VSMC proliferation. The therapeutic potential of PAP-1 was then evaluated in vivo in swine models of ISR and AV. At 15-days follow-up, morphometric analysis demonstrated a substantial reduction of luminal stenosis in the allografts treated with PAP-1 (autograft 2.72 ± 1.79 vs allograft 10.32 ± 1.92 vs allograft + polymer 13.54 ± 8.59 vs allograft + polymer + PAP-1 3.06 ± 1.08 % of luminal stenosis; P = 0.006) in the swine model of femoral artery transplant. In the pig model of coronary ISR, using a prototype of PAP-1-eluting stent, no differences were observed regarding % of stenosis compared to control stents (31 ± 13 % vs 37 ± 18%, respectively; P = 0.372) at 28-days follow-up. PAP-1 treatment was safe and did not impair vascular healing in terms of delayed endothelialization, inflammation or thrombosis. However, an incomplete release of PAP-1 from stents was documented. We conclude that the use of selective Kv1.3 blockers represents a promising therapeutic approach for the prevention of intimal hyperplasia in AV, although further studies to improve their delivery method are needed to elucidate its potential in ISR.

The Interaction of Urinary Components with Biomaterials in the Urinary Tract: Ureteral Stent Discoloration.

Purpose: Ureteral stents are fraught with complications. Not much is known regarding what causes these issues. Studies suggested that discoloration of indwelling stents changes surface characteristics to promote stent-associated complications. Occasional stent discoloration has been observed; however, underlying mechanisms and potential material changes are unknown. In this study, we identify a potential mechanism for stent discoloration and characterize potential changes in stent surface characteristics and their impact on encrustation and bacterial colonization. Materials and Methods: Twenty Polaris Ultra and 20 Percuflex Plus stents (same polymer material) with varying degrees of discoloration were collected from Japanese and Canadian patients. Surface characterization using scanning electron microscopy and Fourier transmission infrared spectroscopy was conducted. Encrustation of variably discolored stents was assessed via atomic absorption spectroscopy and bacterial adhesion to discolored and control stents via colony-forming unit counts. Results: Bismuth subcarbonate was found in control stents, and discoloration was induced via incubation in 1% sodium sulfide and increasing concentrations of hydrochloric acid (HCl) to produce hydrogen sulfide (H2S). Discoloration of either patient-derived stents or in vitro discolored stents did not result in significant changes in stent material or increased rates of encrustation or bacterial adhesion. Conclusions: Ureteral stent discoloration may be triggered by sulfur containing urinary components reacting with bismuth subcarbonate in the stent material, rather than the surface deposition of unusual crystals as previously proposed. Stent discoloration does not result in increased levels of encrustation or bacterial adhesion. Given this, stent discoloration appears to be cosmetic and has no effect on the functionality of the indwelling stent.

Evaluation of a Novel Spun Polytetrafluoroethylene Stent Graft in an Ovine External Iliac Artery Model.

To evaluate the patency, cellular response, and thrombogenicity of a novel vascular stent graft. Test stent grafts, incorporating luminal spun polytetrafluoroethylene and a nonpermeable fluoropolymer layer, and control stent grafts, constructed of permeable expanded polytetrafluoroethylene, were implanted in the external iliac arteries of 14 adult sheep with a median weight of 73.4 kg ranging from 60.6-86.8 kg for 30 (n= 4), 90 (n= 4), and 180 (n= 6) days. Angiographic patency and percent diameter stenosis (%DS) were assessed at termination. Excised stent grafts were fixed and stained for histopathologic analysis, including neointimal coverage (NC) assessment. Test and control device migration occurred in 1 animal, resulting in test device thrombosis. Both devices were excluded from analysis. Mean %DS in test and control implants was 4.6% and 8.2% (P= .563), 2.0% and 10.9% (P= .363), and 2.1% and 10.3% (P= .009) at 30, 90, and 180 days, respectively. Median NC scores at 30, 90, and 180 days were significantly lower in middle test device sections (P < .05). Proximal and distal test and control sections exhibited similar median NC scores at all time periods (P > .05). When present, test and control devices exhibited no neointimal detachment from the graft surface. Except for the migrated test device, no thrombus was observed. Transgraft cellular migration was absent in test devices but present in control devices with tissue accumulation around the stent struts. Test and control devices demonstrated excellent patency in an ovine model. Compared to the control, test devices exhibited significantly lower %DS values at 180 days and significantly lower mid-device NC scores at 30, 90, and 180 days.

Expect the unexpected

To describe our experience with a series of 3 children with the most common congenital uropathy, pelviureteric junction obstruction (PUJO), presenting with uncommon or life-threatening complications from the PUJO itself, or complications of pyeloplasty surgery. The first case (5 year old) presented obtunded with malignant hypertension and PRES (posterior reversible encephalopathy syndrome). She was found to have a severe PUJO with a ruptured renal calyx and large compressive sub capsular urinoma. This Page-kidney type phenomenon was driving the severe hypertension. She was managed with a drain for the sub-capsular urinoma, medical hypertension control and emergency retrograde JJ stent insertion across the PUJO. The second case (infant) presented in acute renal failure and was found to have bilateral PUJO on imaging. She underwent emergency retrograde JJ stenting of the more severely hydronephrotic kidney. The third case (infant) presented with recurrent PUJO and underwent Redo Pyeloplasty. Post-operatively, the distal end of the JJ stent was coiled in the lower ureter, causing a complete obstruction at the VUJ, with perinephric leak from the pyeloplasty wound. The lower end of the stent was negotiated into the bladder with the help of a ureteroscope and without disturbing the pelvic end of the JJ stent. Case1-Recovered well, hypertension resolved and pyeloplasty done electively. Case2-Renal parameters normalised after JJ stent placement, followed by elective pyeloplasty. Case 3-Perinephric leak settled, JJ stent removed after 8 weeks. PUJO, a common uropathy, can be associated with uncommon and severe complications: requiring awareness, prompt diagnosis and astute timely management to tide over the threatening scenarios.

Biodegradable polymer sirolimus-eluting stents versus durable polymer everolimus-eluting stents in patients with ST-segment elevation myocardial infarction (BIOSTEMI): a single-blind, prospective, randomised superiority trial

Newer-generation drug-eluting stents that combine ultrathin strut metallic platforms with biodegradable polymers might facilitate vascular healing and improve clinical outcomes in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention (PCI) compared with contemporary thin strut second-generation drug-eluting stents. We did a randomised clinical trial to investigate the safety and efficacy of ultrathin strut biodegradable polymer sirolimus-eluting stents versus thin strut durable polymer everolimus-eluting stents in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI. The BIOSTEMI trial was an investigator-initiated, multicentre, prospective, single-blind, randomised superiority trial at ten hospitals in Switzerland. Patients aged 18 years or older with acute STEMI who were referred for primary PCI were eligible to participate. Patients were randomly allocated (1:1) to either biodegradable polymer sirolimus-eluting stents or durable polymer everolimus-eluting stents. Central randomisation was done based on a computer-generated allocation sequence with variable block sizes of 2, 4, and 6, which was stratified by centre, diabetes status, and presence or absence of multivessel coronary artery disease, and concealed using a secure web-based system. Patients and treating physicians were aware of group allocations, whereas outcome assessors were masked to the allocated stent. The experimental stent (Orsiro; Biotronik; Bülach, Switzerland) consisted of an ultrathin strut cobalt-chromium metallic stent platform releasing sirolimus from a biodegradable polymer. The control stent (Xience Xpedition/Alpine; Abbott Vascular, Abbott Park, IL, USA) consisted of a thin strut cobalt-chromium stent platform that releases everolimus from a durable polymer. The primary endpoint was target lesion failure, a composite of cardiac death, target vessel myocardial reinfarction (Q-wave and non-Q-wave), and clinically-indicated target lesion revascularisation, within 12 months of the index procedure. All analyses were done with the individual participant as the unit of analysis and according to the intention-to-treat principle. The trial was registered with ClinicalTrials.gov, number NCT02579031. Between April 26, 2016, and March 9, 2018, we randomly assigned 1300 patients (1623 lesions) with acute myocardial infarction to treatment with biodegradable polymer sirolimus-eluting stents (649 patients and 816 lesions) or durable polymer everolimus-eluting stents (651 patients and 806 lesions). At 12 months, follow-up data were available for 614 (95%) patients treated with biodegradable polymer sirolimus-eluting stents and 626 (96%) patients treated with durable polymer everolimus-eluting stents. The primary composite endpoint of target lesion failure occurred in 25 (4%) of 649 patients treated with biodegradable polymer sirolimus-eluting stents and 36 (6%) of 651 patients treated with durable polymer everolimus-eluting stents (difference -1·6 percentage points; rate ratio 0·59, 95% Bayesian credibility interval 0·37-0·94; posterior probability of superiority 0·986). Cardiac death, target vessel myocardial reinfarction, clinically-indicated target lesion revascularisation, and definite stent thrombosis were similar between the two treatment groups in the 12 months of follow-up. In patients with acute STEMI undergoing primary PCI, biodegradable polymer sirolimus-eluting stents were superior to durable polymer everolimus-eluting stents with respect to target lesion failure at 1 year. This difference was driven by reduced ischaemia-driven target lesion revascularisation in patients treated with biodegradable polymer sirolimus-eluting stents compared with durable polymer everolimus-eluting stents. Biotronik.

In-vitro evaluation of a ciprofloxacin- and ivacaftor-coated sinus stent against Pseudomonas aeruginosa biofilms.

We recently developed a novel ciprofloxacin-coated sinus stent capable of releasing antibiotics over a sustained period of time. Ivacaftor is a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator that has synergistic bactericidal activity with ciprofloxacin and also enhances sinus mucociliary clearance. The objective of this study was to optimize and evaluate the efficacy of a ciprofloxacin- and ivacaftor-releasing biodegradable sinus stent (CISS) in vitro. A CISS was created by coating ciprofloxacin/ivacaftor-embedded nanoparticles with an acrylate and ammonium methacrylate copolymer onto a biodegradable poly-L-lactic acid stent. In-vitro evaluation of the CISS included: (1) assessment of drug stability in nanoparticles by zeta potential, and drug-coating stability within the CISS using scanning electron microscopy (SEM); (2) determination of ciprofloxacin- and ivacaftor-release kinetics; and (3) assessment of anti-Pseudomonas aeruginosa biofilm formation by calculating relative optical density units (RODUs) compared with control stents at 590-nm optical density. The presence of drugs and a uniform coating on the stent were confirmed by zeta potential and SEM. Sustained drug release was observed through 21 days without an initial burst release. Anti-biofilm formation was observed after placing the CISS for 3 days onto a preformed 1-day P aeruginosa biofilm. The CISS significantly reduced biofilm mass compared with bare stents and controls (RODUs at 590-nm optical density; CISS, 0.31 ± 0.01; bare stent, 0.78 ± 0.12; control, 1.0 ± 0.00; p = 0.001; n = 3). The CISS maintains a uniform coating and sustained delivery of drugs providing a marked reduction in P aeruginosa biofilm formation. Further studies evaluating the efficacy of CISS in a preclinical model are planned.