Stent Lumen Research Articles

Coronary Artery Stent Evaluation by Combining Iterative Reconstruction and High-resolution Kernel at Coronary CT Angiography

To evaluate stent lumen visualization by combining high-resolution cardiac kernel and the iterative reconstruction (iDose) on an anthropomorphic moving heart phantom and in patients at coronary computed tomography (CT) angiography. We used the moving heart phantom and a 64 detector-row CT, retrospectively gated helical scanning, and image reconstruction. The heart rate was set at nonpulsating condition of 0 beats/min, 50 beats/min, and 80 beats/min. The 120-kV images were reconstructed in synchronization with electrocardiogram data using filtered back projection (FBP) or iDose algorithm and standard kernel/filter (CB) or high-resolution kernel/filter (CD). We measured image noise, the kurtosis, and stent lumen diameter in the phantom study. We also assessed the visual inspections by two radiologists. With cardiac motion at 50 and 80 beats/min, the difference of kurtosis improved with CD relative to CB (P < .05). iDose algorithm with level 7 provided lowest noise, with no statistically significance in difference of the kurtosis relative to level 4 (P > .05). Without cardiac motion at 0 beats/min, the stent lumen diameter measurements with CD kernel were better relative to CB kernel (P < .05). In addition, no significant difference was found in stent lumen diameter between iDose level 4 and level 7 (P > .05). The use of iDose and a sharp kernel allowed improved stent visualization at a lower radiation dose.

In vitro stent lumen visualisation of various common and newly developed femoral artery stents using MR angiography at 1.5 and 3 tesla

To evaluate stent lumen assessment of various commonly used and newly developed stents for the superficial femoral artery (SFA) using MR angiography (MRA) at 1.5 and 3 T. Eleven nitinol stents and one cobalt-chromium stent were compared regarding stent lumen visualisation using a common three-dimensional MRA sequence. Maximum visible stent lumen width and contrast ratio were analysed in three representative slices for each stent type. A scoring system for lumen visualisation was applied. Nitinol stents showed significantly better performance than the cobalt chromium stent (P < 0.05) at 1.5 and 3 T. Maximum visible stent lumen ranged between 43.4 and 95.5 %, contrast ratio between 7.2 and 110.6 %. Regarding both field strengths, seven of the nitinol stents were classified as "suitable". Three nitinol stents were "limited", and one nitinol stent and the cobalt chromium stent were "not suitable". Intraluminal loss of signal and artefacts of most of the SFA stents do not markedly limit assessment of stent lumen by MRA at 1.5 and 3 T. MRA can thus be considered a valid technique for detection of relevant in-stent restenosis. Applied field strength does not strongly influence stent lumen assessment in general, but proper choice of field strength might be helpful.

Percutaneous removal of a fully expanded SMART stent from the pulmonary artery using various adjunctive techniques

A 36-year-old man with an implanted arteriovenous shunt for hemodialysis was referred for shunt malfunction. Venography of the right upper extremity showed occlusion of the subclavian vein, and a SMART stent was deployed. The fully expanded stent immediately migrated centrally into the left pulmonary artery. As initial efforts to pass a snare over the stent failed, we intentionally passed a microguidewire through stent interstices, snared the end of the microguidewire to create a loop, and pulled the stent/microguidewire/snare combination back into the right ventricle where it separated from the loop because of stent mesh destruction. As the stent remained in the right ventricle, we advanced a 0.035-in. guidewire into the stent lumen, passed an angioplasty balloon over the guidewire, inflated the balloon in the stent, and performed pull-back into the right distal external iliac artery. The stent was then surgically removed via a right inguinal incision without eliciting any complications. Although retrieval of the stent malpositioned in the pulmonary artery was difficult, we retrieved it safely by applying various adjunctive techniques.

Encrustation of urologic double pigtail catheters—an ex vivo optical coherence tomography (OCT) study

This study aims to evaluate whether optical coherence tomography (OCT) using both the surface and the endoluminal technique is feasible to investigate the locations and degree of encrustation process in clinically used ureteral stents. After removal from patients, 14 polyurethane JJ stents were investigated. A fresh JJ served as a control. The external surfaces were examined using an endoscopic surface OCT whereas the intraluminal surfaces were investigated by an endoluminal radial OCT device. The focus was on detection of encrustation or crystalline sedimentation. In 12 female and two male patients, the median indwelling time of the ureteral catheter was 100 days (range, 19-217). Using the endoluminal OCT, the size and grade of intraluminal encrustation could be expressed as a percentage relating to the open lumen of the reference stent. The maximum encrustation observed resulted in a remaining unrestricted lumen of 15-35 % compared to the reference. The luminal reduction caused by encrustation was significantly higher at the proximal end of the ureteral stent as compared to its distal part. The extraluminal OCT investigations facilitated the characterization of extraluminal encrustation. OCT techniques were feasible and facilitated the detection of encrustation of double pigtail catheters on both the extra and intra luminal surface. Quantitative expression of the degree of intraluminal encrustation could be achieved, with the most dense and thickened occurrence of intraluminal incrustation in the upper curl of the JJ stent.

Paclitaxel-coated balloon plus bare metal stent vs. sirolimus-eluting stent in de novo lesions: an IVUS study

Restenosis after PCI and/or stent implantation is still one of the challenging problems in the field of interventional cardiology. Different approaches to prevent and to treat restenosis include the use of drug-eluting stents, which have shown to reduce restenosis. Another approach is the treatment with drug-coated balloons. This approach has been proven for different indications, e.g., in-stent restenosis and treatment of peripheral artery disease. Patients from the PEPCAD III multicentre randomised trial in two study centres (Homburg and Hannover, Germany) were asked to participate in this intravascular ultrasound (IVUS) study at nine-month follow-up. At baseline (nine months before), patients were randomly assigned to receive either a paclitaxel-coated balloon (drug-coated balloon [DCB]) plus a premounted bare metal stent (DCB/BMS) or a sirolimus-eluting stent (drug-eluting stent [DES]) to treat de novo lesions. IVUS at follow-up was performed in order to analyse the restenosis for potential understanding of the mechanism leading to restenosis. IVUS data is available for 55 patients; 26 patients were treated with Cypher(®) DES (Cordis, Miami Lakes, FL, USA) and 29 patients with DCB/BMS. A focal malapposition of the stent was seen in six patients; four after DES and two after DCB/BMS. Stent expansion, calculated as symmetric expansion index, was equal for both groups (0.89 and 0.90). Mean stent area was also equal for both groups (6.25 ± 1.7 vs. 5.65 ± 1.5 mm(2), p=n.s.). The neointimal hyperplasia (calculated as stent area minus lumen area) was significantly different between both groups (0.69 ± 0.49 [DES] vs. 1.08 ± 0.53 mm(2) [DCB/BMS], p<0.01). This resulted in a significantly higher in-stent restenosis in the DCB/BMS group (19.7 vs. 11 %, p<0.01). There is no evidence of geographical mismatch. First IVUS insights for the DCB/BMS showed a comparable, low incidence of malapposition for the combination of drug-coated balloon and premounted bare metal stent compared to the DES, and stent expansion was good and comparable to DES. However, at nine-month follow-up, the combination of drug-coated balloon and premounted bare metal stent showed higher in-stent restenosis compared to sirolimus DES. Geographical mismatch can be excluded as a reason for this result.

Stent-assisted Coiling of Complex Intracranial Aneurysms

Objective: To discuss the indications, technical details, and safety of endovascular treatment of complex intracranial aneurysms using coiling in combination with stent-assisted remodeling of the parent artery. Methods: Forty-one consecutive patients with complex intracranial aneurysms were treated with stent-assisted coiling. Three patients had double aneurysms that were located within 5mm. Nine patients had giant wide-necked aneurysms. Two patients had neck remnants at 2 years after the initial coiling. One patient had recurrent aneurysm at 3 years after the initial coiling. Twenty-six patients had acutely ruptured aneurysms. Neuroform, LEO and SolitaireAB stents, and Matrix, Orbit coils were used. Results: All endovascular procedures were performed uneventfully. There were no complications. Postoperative angiography showed complete dense packing (95% to 100%) in all aneurysms, except 2 giant aneurysms, which had subtotal embolization. In patients with acutely ruptured aneurysms, there was no intrastent thrombosis or stenosis of the stent lumen. Twenty-one patients underwent angiography at 3 to 6 months postoperatively. All of them showed a good outcome, except that one giant aneurysm showed a slight residual filling inside the sac. Discussion: Stent-assisted remodeling of the parent artery in combination with various types of coils can increase the cure rate of intracranial complex aneurysms. In patients with acutely ruptured aneurysms, antiplatelet drugs should be weighed against the risks of possible open surgeries. Although we have not encountered complications in our emergent cases without using antiplatelet drugs, we should still be cautious when deploying stent without anticoagulation treatment.

Imaging of Coronary Stents by Coronary CT-Angiography: Current Status

Coronary CT-angiography evolved as a valuable tool in the diagnostic work-up of patients after coronary revascularization therapy. With 64-slice or newer generation CT scanners it has a negative predictive value in the range of 98 %. Therefore, it is increasingly used to rule out in-stent restenosis. However, about 10 % to 15 % of stents are not accessible mostly due to motion or metal artifacts. Best results are achieved in stents ≥3 mm having thin stent struts. While the diagnosis of in-stent restenosis is currently based on the direct morphologic assessment of the stent lumen, functional information on the hemodynamic significance of in-stent restenosis will become available with the most recent generation of CT-scanners by means of myocardial perfusion imaging. This review describes technical considerations and summarizes the current evidence for stent imaging by means of coronary CT-angiography.

4D phase contrast flow imaging for in-stent flow visualization and assessment of stent patency in peripheral vascular stents – A phantom study

Purpose4D phase contrast flow imaging is increasingly used to study the hemodynamics in various vascular territories and pathologies. The aim of this study was to assess the feasibility and validity of MRI based 4D phase contrast flow imaging for the evaluation of in-stent blood flow in 17 commonly used peripheral stents. Materials and methods17 different peripheral stents were implanted into a MR compatible flow phantom. In-stent visibility, maximal velocity and flow visualization were assessed and estimates of in-stent patency obtained from 4D phase contrast flow data sets were compared to a conventional 3D contrast-enhanced magnetic resonance angiography (CE-MRA) as well as 2D PC flow measurements. ResultsIn all but 3 of the tested stents time-resolved 3D particle traces could be visualized inside the stent lumen. Quality of 4D flow visualization and CE-MRA images depended on stent type and stent orientation relative to the magnetic field. Compared to the visible lumen area determined by 3D CE-MRA, estimates of lumen patency derived from 4D flow measurements were significantly higher and less dependent on stent type. A higher number of stents could be assessed for in-stent patency by 4D phase contrast flow imaging (n=14) than by 2D phase contrast flow imaging (n=10). Conclusions4D phase contrast flow imaging in peripheral vascular stents is feasible and appears advantageous over conventional 3D contrast-enhanced MR angiography and 2D phase contrast flow imaging. It allows for in-stent flow visualization and flow quantification with varying quality depending on stent type.

Time-resolved CT Angiography for the Detection and Classification of Endoleaks

To assess the feasibility and diagnostic performance of time-resolved computed tomographic (CT) angiography in the detection and classification of endoleaks after endovascular aortic aneurysm repair (EVAR) in high-risk patients. The study was approved by our ethics committee. Written informed consent was obtained from all participating patients. Fifty-four patients (42 male and 12 female patients; mean age, 70.9 years ± 9.3 [standard deviation]) with either thoracic (n = 8) or abdominal (n = 46) aortic aneurysms treated with a stent-graft were prospectively included. The patients were examined with a time-resolved CT angiographic protocol consisting of 12 low-dose phases (80 kVp; 120 mAs [effective]; scan range, 27 cm), with 60 mL of iomeprol. Patients with abdominal aneurysm repair also underwent contrast material-enhanced (CE) ultrasonography (US). The time delay between contrast enhancement within the stent lumen and the endoleak was measured. Effective radiation dose was calculated from the scanner protocols. Measures of diagnostic performance for the detection of endoleaks were calculated for time-resolved CT angiography, with CE US serving as the reference standard. All time-resolved CT angiographic data sets were diagnostic. Mean effective radiation dose was 14.6 mSv. Four thoracic and 19 abdominal endoleaks were identified by using time-resolved CT angiography. Seventeen of 19 abdominal endoleaks were confirmed with CE US. This rate resulted in a sensitivity of 94%, a specificity of 93%, a positive predictive value of 89%, and a negative predictive value of 96% for time-resolved CT angiography after abdominal EVAR. Type I endoleaks showed significantly earlier mean peak contrast enhancement (0.28 second ± 0.83) compared with that for type II endoleaks (9.17 seconds ± 3.59, P < .0001). Time-resolved CT angiography with 12 low-dose phases is feasible for patients after thoracic and abdominal EVAR. The protocol approximates the radiation dose of standard triphasic protocols. Its dynamic information differentiates types of endoleaks and shows high diagnostic performance.

미세단층촬영기법을 이용한 관상동맥 스텐트의 동물 모델 분석

미세단층촬영기법은 전임상 동물실험 분석시 고해상도의 혈관 영상화를 위한 중요한 수단이다. 이는 조직 분석과 같이 샘플 훼손이 예상되는 분석 작업 이전에 비파괴적인 방법으로 2차원 또는 3차원 이미지 재구성할 수 있는 장점이 있다. 본 연구에서는 생체 이식용 의료기기인 스텐트를 동물모델에서 전임상 분석을 하는데 있어 미세단층촬영기법의 활용방법을 제시하고 금속 스텐트(BMS)와 약물(paclitaxel)이 코팅된 스텐트(DES)의 스텐트 내 재협착정도(ISR)를 토끼 모델을 이용하여 평가하고자 하였다. BMS와 DES를 무작위적으로 토끼의 장골동맥에 식립하고 4주 후에 스텐트가 식립된 주위 혈관을 적출한 다음 스텐트 내강에 조영제를 투여하였다. 미세단층촬영기를 이용하여 50kV/200<TEX>${\mu}A$</TEX>의 X-ray 조사량으로 샘플을 스캔하였다. 정량적 분석을 위해 CTAN 소프트웨어를 이용하여 관심영역을 지정하여 정량적 분석을 수행하였다. 피폭 대상에 따라 각기 다른 CT값(Hounsfied Unit)을 획득할 수 있었으며(스텐트 영역; 약 1.2, 조영제 영역; 0.12~0.17, X-ray 비흡수 영역; 0~0.06), 이를 이용하여 2차원, 3차원적 영상을 획득하고 스텐트내 재협착 면적을 산출하였다. 조직병리학적 분석의 염증지수에 해당할 수 있는 확장된 스텐트의 크기를 측정하였을 때 BMS와 DES간의 유의한 차이가 나타나지 않았다. 또한 BMS 그룹의 ISR(<TEX>$1.52{\pm}0.48mm2$</TEX>)이 DES의 ISR(<TEX>$0.94{\pm}0.42mm2$</TEX>)에 비해 약 1.6배 높은 것으로 확인되었다. 이는 DES에 코팅된 paclitaxel이 세포 증식을 억제하여 스텐트 내강으로 증식하는 것을 저해하였기 때문으로 판단된다. 2차원적 분석 결과 BMS의 재협착 분포는 스텐트 중간 영역에서 전면부와 후면부에 비해 비교적 높은 것으로 확인되었다. 이러한 연구 결과로 볼 때 미세단층촬영기법은 비파괴적인 방법으로 분석이 가능하며 정량적 분석을 위한 기존의 복잡한 조직병리학적 분석법의 보조적인 수단으로 활용될 수 있을 것이다. Micro-computed tomography (microCT) is an important tool for preclinical vascular imaging, with micron-level resolution. This non-destructive means of imaging allows for rapid collection of 2D and 3D reconstructions to visualize specimens prior to destructive analysis such as pathological analysis. Objectives. The aim of this study was to suggest a method for ex vivo, postmortem examination of stented arterial segments with microCT. And ex vivo evaluation of stents such as bare metal or drug eluting stents on in-stent restenosis (ISR) in rabbit model was performed. The bare metal stent (BMS) and drug eluting stent (DES, paclitaxel) were implanted in the left or right iliac arteries alternatively in eight New Zealand white rabbits. After 4 weeks of post-implantation, the part of iliac arteries surrounding the stent were removed carefully and processed for microCT. Prior to microCT analysis, a contrast medium was loaded to lumen of stents. All samples were subjected to an X-ray source operating at 50 kV and 200 <TEX>${\mu}A$</TEX> by using a 3D isotropic resolution. The region of interest was traced and measured by CTAN analytical software. Objects being exposed to radiation had different Hounsfield unit each other with values of approximately 1.2 at stent area, 0.12 ~ 0.17 at a contrast medium and 0 ~ 0.06 at outer area of stent. Based on above, further analyses were performed. As a result, the difference of lengths and volumes between expanded stents, which may relate to injury score in pathological analysis, was not different significantly. Moreover, ISR area of BMS was 1.6 times higher than that of DES, indicating that paclitaxel has inhibitory effect on cell proliferation and prevent infiltration of restenosis into lumen of stent. And ISR area of BMS was higher (<TEX>$1.52{\pm}0.48mm^2$</TEX>) than that of DES (<TEX>$0.94{\pm}0.42mm^2$</TEX>), indicating that paclitaxel has inhibitory effect on cell proliferation and prevent infiltration of restenosis into lumen of stent. Though it was not statistically significant, it showed that the extent of neointema of mid-region of stents was relatively higher than that of anterior and posterior region in parts of BMS as showing cross-sectional 2-D image. suggest that microCT can be utilized as an accessorial tool for pathological analysis.

Endoscopic ultrasound-guided gastroenterostomy using novel tools designed for transluminal therapy: a porcine study

Surgical gastroenterostomy is associated with appreciable morbidity and mortality. We evaluated the technical feasibility and outcomes of a new method of endoscopic ultrasound (EUS)-guided gastroenterostomy using novel tools designed for transluminal therapy. In one acute and four survival female pigs, a gastroenterostomy was created under EUS guidance. Novel tools used included: (i) an anchor wire; (ii) an access device; (iii) a fully covered metal stent with bilateral lumen-apposing anchors. The anchor guide wire was inserted through a standard 19-G fine needle aspiration (FNA) needle to appose the small-bowel and stomach walls. The access device created a 3.5-mm fistula opening for insertion of the stent delivery catheter. The stent lumen was dilated to 10 mm to pass a gastroscope into the small bowel. The procedure was technically successful in all animals. No bleeding occurred. In one acute animal, necropsy showed good stent position and no tissue injury. In four survival animals, the stents remained fully patent and all animals showed normal eating behavior without signs of infection. Stents were easily removed without tissue trauma at 4.5 weeks (n = 3) or 5.5 weeks (n = 1). After stent removal, the tracts appeared mature and were easily intubated with the gastroscope. Necropsy and histopathology showed complete fusion of the stomach and small-bowel wall layers at the site of gastroenterostomy. EUS-guided gastroenterostomy is feasible using novel tools with no adverse outcomes in a survival porcine model. Further study of this is indicated as an alternative to surgical bypass for the palliation of malignant gastric outlet obstruction in appropriately selected patients.

Visualization of stent lumen in MR imaging: relationship with stent design and RF direction.

Magnetic resonance imaging (MRI) visualization of metallic stent lumens is possible if the stent structure counteracts eddy currents in the lumen induced by the radio frequency magnetic field, B(1). To examine the effectiveness of various stent designs in counteracting eddy currents, we anchored eight copper stent models and 2 commercially available nickel-titanium alloy (Nitinol) stents in a gel phantom, perpendicular or parallel to the direction of B(1). A mesh stent lumen showed hypointensity irrespective of its alignment relative to B(1). A solenoid stent lumen showed hypointensity with the stent axis parallel to B(1), but it had the same signal intensity as outside the lumen when perpendicular to B(1). A Moebius stent lumen showed no signal reduction, irrespective of alignment relative to B(1). Lumens of the commercially available stents showed hypointensity regardless of alignment relative to B(1). Computer simulation revealed that the signal intensities of the stents corresponded to magnetic flux densities of B(1) in the stents, which are modified by the structure of the stent. While in vivo MRI viewing of a Moebius stent lumen is likely possible regardless of axis alignment, inherent structural weakness may be problematic. As a more practical choice, the solenoid stent is easier to manufacture and generates no hypointensive signal when the axis is parallel to B(0).

A prospective group sequential study evaluating a new type of fully covered self-expandable metal stent for the treatment of benign biliary strictures (with video)

Fully-covered self expandable metal stents (fcSEMSs) are an alternative to progressive plastic stenting for the treatment of benign biliary strictures (BBS) with the prospect of a higher treatment efficacy and the need for fewer ERCPs, thereby reducing the burden for patients and possibly costs. Key to this novel treatment is safe stent removal. To investigate the feasibility and safety of stent removal of a fcSEMS with a proximal retrieval lasso: a long wire thread integrated in the proximal ends of the wire mesh that hangs freely in the stent lumen. Pulling it enables gradual removal of the stent inside-out. A secondary aim was success of stricture resolution. Non-randomized, prospective follow-up study with 3 sequential cohorts of 8 patients with BBS. Academic tertiary referral center. Eligible patients had strictures either postsurgical (post-cholecystectomy (LCx) or liver transplantation (OLT)), due to chronic pancreatitis (CP), or papillary stenosis (PF). Strictures had to be located at least 2 cm below the liver hilum. All patients had one plastic stent in situ across the stricture and had not undergone previous treatment with either multiple plastic stents or fcSEMS. The first cohort of patients underwent stent placement for 2 months, followed by 3 months if the stricture had not resolved. The second and third cohort started with 3 months and 4 months, respectively, both followed by another 4 months if indicated. Treatment success was defined by stricture resolution at cholangiography, the ability to pass an inflated extraction balloon and clinical follow-up (at least 6 months). safety of stent removal. Secondary outcomes were complications and successful stricture resolution. A total of 23 patients (11 female; 20-67 yrs) were eligible for final analysis. One patient developed a malignant neuroendocrine tumor in the setting of CP. Strictures were caused by CP (13), OLT (6), LCx (3) and PF (1). In total 39 fcSEMS were placed and removed. Removals were easy and without complications. Transient pain after insertion was common (13 of 23/56%) but was easily managed by analgesics in all patients. Other complications were cholecystitis (1), cholangitis due to stent migration (1, stent replaced) or stent clogging (2, managed endoscopically) and worsening of CP (2). In these patients, the fcSEMS was removed and replaced after pancreatic sphincterotomy and PD stent placement. Median follow-up was 15 months (range 11-25). Overall treatment success was 61% (14/23); in the CP group 46%, in the remaining patients 80% (p = 0.11). Patients with stricture resolution after removal of the first stent (n = 7; success 6/7) showed a trent towards a more sustained treatment success than patients who needed a 2nd stent placement (n = 16; success 8/16); p = 0.12). Small number of patients with regard to secondary outcomes. Removal of a new type of fcSEMS with a proximal retrieval lasso in patients with BBS proved easy and uncomplicated. Treatment success for CP strictures was higher compared to what is known from results of progressive plastic stenting protocols. For other indications treatment success was comparable to progressive plastic stenting, but with the prospect of fewer ERCP procedures.

Abstract 2884: Angiographic Lumen Changes From Oversized Neuroform Stent Implantation

Introduction: The effect of oversized intracranial stent implantation, and the potential for excessive neointimal hyperplasia from the resulting chronic outward radial force, has not been previously reported. We sought to compare the angiographic narrowing associated with implantation of oversized Neuroform stents overlapping vessels of different diameters. Methods: We reviewed an aneurysm database and identified patients treated with stent-assisted coil embolization involving stent placement overlapping a vessel size transition. Patient demographics and lesion characteristics were extracted from chart review. A submillimeter digital caliper was used for angiogram measurement of lumen diameter at four sites ( figure ). The relationship between lumen diameter and stent oversizing was compared with student’s t-test and Pearson’s correlation. Results: Twenty vessels were identified in 18 patients, providing 80 paired data points. Mean age was 52 years (SD 12), with mean follow-up time of 8 months (SD 6). The distribution of vessel transitions included BA to PCA (n = 8), A1 to A2 or M1 to M2 (n = 8), ICA to ACA or MCA (n = 3), and Vertebral artery to PICA (n = 1). Stent diameter ranged from 3 mm to 4.5 mm, and the average oversizing in the smaller diameter parent vessel landing-zone was 1.75 mm (range 0.8 to 2.9 mm) greater than the vessel diameter. The mean change in lumen size from pre-stent implantation to follow-up was not significantly different for any of the four sites; the proximal end-stent decreased by 5.5% (SD 19.7), proximal mid-stent increased by 7.3% (SD 18.8), distal mid-stent increased by 14.7% (SD 13.8), and the distal end-stent decreased by 0.9% (SD 13.1). Stent oversizing by less than a factor of 1.65 resulted in a mean lumen loss of 4.1% (SD 15.6), while oversizing by greater than a factor of 1.65 resulted in a mean lumen gain of 11.1% (SD = 17.2), (p = 0.006). Conclusions: These data suggest oversized Neuroform stent implantation within the intracranial vasculature does not lead to increased stenosis. Stent oversizing by a factor of 1.65 or more leads to significant persistent luminal gain. The non-significant trend toward lumen loss at the stent tines suggests diminished radial force or greater neointimal hyperplasia at these sites, however persistent luminal gain from the oversized stent radial force likely predominates over any neointimal hyperplasia. Figure . A NF stent overlapping the M1 and M2 segments (A, tines indicated by white arrows). Four points of measurement (B), proximal tines (1.), mid-stent in proximal landing zone (2.), mid-stent in distal landing zone (3.), and distal tines (4.).

Clinical evaluation of a novel lumen-apposing metal stent for endosonography-guided pancreatic pseudocyst and gallbladder drainage (with videos)

Tubular plastic and metal stents have inherent shortcomings when used for transenteric drainage of fluid collections. To evaluate a novel lumen-apposing, self-expandable metal stent for EUS-guided drainage of pancreatic pseudocysts and the gallbladder. Retrospective case series. Tertiary-care academic medical center. This study involved 15 patients (median age 54 years) with symptomatic pancreatic pseudocysts who underwent 12 transgastric and 3 transduodenal pseudocyst drainage procedures. Five patients (median age 69.5 years) with acute cholecystitis underwent 4 cholecystoduodenostomies and 1 cholecystogastostomy. Stent deployment under EUS guidance, passage of an endoscope through the stent lumen for pseudocystoscopy or cholecystoscopy, transenteric endoscopy-guided interventions including biopsy, necrosectomy, and stone removal. Technical and clinical success. All stents were successfully deployed without complication, with a median time to removal of 35 days. All pseudocysts resolved after a single drainage procedure. One stent migrated into the stomach, and the remaining 14 were found to be patent at the time of removal. There was no pseudocyst recurrence during the 11.4-month median follow-up period. One gallbladder stent remains indwelling and fully patent at 12 months. Resolution of acute cholecystitis was observed immediately after stent implantation. No recurrence of symptoms was observed during a median follow-up period of 9 months. Retrospective study, small sample size, lack of control patients. Transenteric drainage of pancreatic pseudocysts and the gallbladder by using a novel, lumen-apposing, metal stent was accomplished with high technical and clinical success in this pilot observational study. Further studies are warranted.

Late Positive Remodeling and Late Lumen Gain Contribute to Vascular Restoration by a Non-Drug Eluting Bioresorbable Scaffold

The interplay between mechanical dilatation, resorption, and arterial response following implantation of bioresorbable scaffolds is still poorly understood. Long-term geometric changes in porcine coronary arteries in relation to gradual degradation of bioresorbable scaffolds were assessed in comparison with bare metal stents (BMS). Intravascular ultrasound (IVUS)-derived lumen, outer stent/scaffold, and reference vessel areas were evaluated in 94 polymer scaffolds and 46 BMS at 5 days and 3, 6, 12, 18, 24, and 55 months, in addition to polymer scaffold radial crush strength and molecular weight (M(W)) at 3, 6, and 12 months. BMS outer stent area and lumen area remained constant through 55 months (P=0.05, but within 1 standard deviation of 100%, and P=0.58, respectively), while significant increases were exhibited by polymer-scaffolded vessels with the maximum late lumen gain at 24 months, paralleled by the outer scaffold area increase, and then remaining at that increased level at 55 months (P<0.01). By 12 months polymer scaffolds experienced significant reductions in radial strength and M(W), while the animals underwent the largest weight gain. At 3 months and beyond, the patency ratio (lumen area/reference vessel area) of BMS remained constant (0.71 to 0.85, P=0.49). In contrast, that of polymer scaffolds increased and approached 1 (P=0.13). Bioresorbable polymer scaffolds allow restoration of the treated segment's ability to remodel outward to achieve level lumen transition between reference vessel and scaffold-treated regions, a process mediated by animal growth and scaffold degradation. This also introduces a challenge to standard analyses of IVUS outcomes relying on constant stent diameters over time.

Outcomes After Stent Implantation for the Treatment of Congenital and Postoperative Pulmonary Vein Stenosis in Children

Pulmonary vein stenosis (PVS) is a rare condition that can lead to worsening pulmonary hypertension and cardiac failure in children, and it is frequently lethal. Surgical and transcatheter approaches are acutely successful but restenosis is common and rapid. We reviewed outcomes among patients who underwent transcatheter pulmonary vein stent implantation for congenital or postoperative PVS at <18 years of age. A total of 74 pulmonary veins were stented with bare metal, drug-eluting, or covered stents in 47 patients. Primary diagnoses included PVS associated with anomalous venous return in 51%, PVS associated with other congenital cardiovascular defects in 36%, and congenital ("de novo") PVS in 13% of patients. Median age at the time of pulmonary vein stent implantation was 1.4 years. During a median cross-sectional follow-up of 3.1 years, 21 patients died. Estimated survival was 62±8% at 1 year and 50±8% at 5 years after pulmonary vein stent implantation. Stent placement acutely relieved focal obstruction in all veins. Of the 54 stents reexamined with catheterization, 32 underwent reintervention. Freedom from reintervention was 62±7% at 6 months and 42±7% at 1 year. Stent occlusion was documented in 9 cases and significant in-stent stenosis in 17 cases. Stent implantation diameter ≥7 mm was associated with longer freedom from reintervention (hazard ratio, 0.32; P=0.015) and from significant in-stent stenosis (hazard ratio, 0.14; P=0.002). Major acute complications occurred in 5 cases. Transcatheter stent implantation can acutely relieve PVS in children, but reintervention is common. Larger stent lumen size at implantation is associated with longer stent patency and a lower risk of reintervention.

Paclitaxel-eluting stents reduce neointimal hyperplasia compared to bare metal stents in saphenous vein grafts: intravascular ultrasonography analysis of the SOS (Stenting of Saphenous Vein Grafts) trial

To compare the intravascular ultrasonography (IVUS) findings between saphenous vein grafts (SVG) treated with paclitaxel-eluting stents (PES) vs. bare metal stents (BMS) in the Stenting Of Saphenous Vein Grafts (SOS) trial. Of the 80 SOS trial patients, 38 had both baseline and follow-up IVUS examination and were included in this substudy: 17 patients received 28 BMS in 26 lesions and 21 patients received 30 PES in 28 lesions. Quantitative IVUS analysis was performed to determine the volume of in-stent neointimal hyperplasia (NIH) - defined as the difference between stent volume and lumen volume in the stented segments. Baseline characteristics were similar between patients who did and did not undergo baseline and follow-up IVUS. Patients receiving BMS and PES had similar stent and lumen volumes immediately after stenting. At 12-month follow-up, compared to BMS, PES-treated lesions had significantly less NIH volume (3.4 vs. 21.9 mm³, p<0.001) and neointima hyperplasia progression (1.6 vs. 17.1 mm³, p<0.001). No significant differences were seen in the 5 mm segment proximal and distal to the stent. Compared to BMS, use of PES in SVG lesions is associated with significantly lower NIH formation, which may help explain the improved clinical outcomes with PES in these lesions.

Evaluation of coronary artery in-stent patency using 64-slice computed tomography

Surveillance conventional coronary angiography (CCA) is recommended after stent supported percutaneous coronary intervention due to the unpredictable occurrence of in-stent restenosis (ISR). We explored the ability of 64-slice computed tomography angiography (CTA) to detect ISR after stenting of the coronary artery and analyzed the factors influencing imaging quality. Forty-five consecutive patients (29 stents) were examined by both CCA and 64-slice CTA after percutaneous coronary intervention. We analyzed the correlation between the image quality and heart rate, diameter, position, and stent-strut thickness. Compared with the CCA, the sensitivity, specificity, positive predictive value, and negative predictive value of 64-slice CTA for the detection of ISR were calculated. Between the patent group and ISR group, different computed tomography attenuation values of the in-stent lumen and artery 5 mm proximal and distal to the stent were also analyzed. All stents were clearly visualized. With regard to the differences in heart rate, stent position, stent diameter, and stent-strut thickness among the different image quality groups, the P values were 0.47, 0.60, 0.04, and <0.01, respectively. Compared with CCA, the sensitivity, specificity, positive predictive value, and negative predictive value of 64-slice CTA were 100, 95.2, 88.9, and 100%, respectively. Between patent and ISR groups, the P values for the differences in CTA attenuation values of the in-stent lumen and artery 5 mm distal to the stent were 0.007 and 0.04, respectively. We found that 64-slice spiral CTA is a reliable noninvasive diagnostic method that can display the stent lumen clearly and is especially helpful for patient follow-up.

Endoleak After Endovascular Aneurysm Repair: Evaluation of a Single-Acquisition CTA Protocol Using a Prebolus

To investigate a single-acquisition computed tomographic angiography (CTA) protocol using a prebolus injection technique to visualize the stent-graft lumen and endoleak after endovascular aneurysm repair (EVAR). Of 162 EVAR patients referred for CTA over a 2-year period, 18 (15 men; mean age 66.4 years) with an endoleak met the study inclusion criteria, which included constant endoleak size and scans using 3 different CT protocols at least once during follow-up: monophasic CTA (C1), biphasic CTA (C2.1 and C2.2), and single-acquisition CTA using a prebolus (PB). All CTA examinations were performed with the same overall volume of contrast medium (120 mL) and were started manually using a bolus-tracking technique. Attenuation was measured within the aortic lumen proximal to the stent prosthesis (Ao) and within the endoleak itself (EL). Mean attenuation ranged between 200 (C2.2) and 313 HU (C2.1) within Ao and between 172 (C2.2) and 235 HU (C2.1) within the endoleak. The attenuation differences between Ao (C1) and Ao (PB), as well as between Ao (C2.1) and Ao (PB), were not statistically significant, while the attenuations of Ao (C2.2) and Ao (PB) differed significantly (p<0.001), with higher attenuation in PB. Compared to EL (PB), none of the mean EL attenuation values (C1, C2.1, and C2.2) differed significantly. This prebolus CTA protocol combines late-phase attenuation of a biphasic image acquisition protocol for endoleak visualization with high opacification of the stent lumen without exposing the patient to radiation twice.