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Sample records for expandable metal stent

  1. Comparison of Self-Expanding Polyethylene Terephthalate and Metallic Stents Implanted in Porcine Iliac Arteries

    SciTech Connect

    Wilczek, Krzysztof; Scheerder, Ivan de; Wang Kai; Verbeken, Eric; Piessens, Jan

    1996-05-15

    Purpose: Comparison of the biocompatibility of self-expanding polyethylene terephthalate (PET) stents with self-expanding metallic stents (Wallstents). Methods: Diameter- and length-matched PET stents and Wallstents were symmetrically implanted in the paired iliac arteries of 13 crossbred domestic swine. Stent deployment was studied angiographically and with intravascular ultrasound immediately after stent implantation. The angiographic stented lumen diameter was measured using quantitative vessel analysis before, immediately after stenting, and at 6-week follow-up. Cross-section histopathology and area morphometry were performed. Results: Immediately poststenting, intravascular ultrasound revealed proximal dislocation of 5 of the 13 PET stents, whereas all metal stents were firmly embedded at the implantation site. At 6-week follow-up, three of the remaining PET stents were totally or subtotally occluded by organized thrombus, whereas all metal stents were patent. Compared with immediately poststenting, the angiographic lumen diameter within the five remaining PET stents was reduced by 30%, and that of the metallic stents was virtually unaltered (p < 0.02). This observation was confirmed by postmortem morphometry, wherein the PET-stented vessel segments a diameter stenosis of 40% was measured vs only 9% in the metallic stents (p < 0.0001). Conclusion: PET-stent deployment is difficult to control due to the lack of radiopacity of this stent. PET stents seem to be more thrombogenic and lead to significantly more neointimal proliferation than metallic stents.

  2. Self-expandable metallic stents in nonmalignant large airway disease.

    PubMed

    Fortin, Marc; MacEachern, Paul; Hergott, Christopher A; Chee, Alex; Dumoulin, Elaine; Tremblay, Alain

    2015-01-01

    Airway self-expandable metallic stents (SEMS) were initially studied in malignant airway obstruction; however, their use in benign airway diseases has become progressively more frequent. This may be explained by their ease of insertion compared with silicone stents, which require rigid bronchoscopy for insertion. While initial experience with SEMS in benign disease suggested efficacy and promising short-term safety profile, long-term follow-up revealed significant complication rates. In addition to a high complication rate, the management of these complications is made more difficult by the semipermanent nature of these devices. Reported complications include infection, granulation tissue formation, stent migration, stent fracture, airway perforation and fistula formation, as well as extension of the initial injury, potentially eliminating other therapeutic options such as surgical resection. Therefore, SEMS should only be used in nonmalignant large airway disease as a last resort for patients in whom other endoscopic methods, including silicone stents and dilations, as well as surgical options have failed or are technically not feasible.

  3. Role of laser photoablative therapy and expandable metal stents in colorectal carcinoma

    NASA Astrophysics Data System (ADS)

    Chennupati, Raja S.; Trowers, Eugene A.

    2000-05-01

    Metallic stents are effective in relieving colorectal obstruction in more than 80% of cases. Self expanding metallic stents allow for decompression of the proximal colon and preoperative bowel cleansing. Hence, emergent surgery for large bowel obstruction with its associated high morbidity and mortality might be avoided. Endoscopic laser photoablation and stent placement may successfully palliate inoperable colorectal cancer patients by maintaining luminal patency and avoiding the need for a colostomy. Major complications associated with metallic stents include pressure necrosis, perforation, bleeding and migration. The effectiveness of expandable metallic stents in obstructive colorectal carcinoma is critically reviewed. The authors present a concise review of the effectiveness of endoscopic laser photoablation and expandable metal stent placement.

  4. Thoracic Discitis as a Complication of Self-Expanding Metallic Stents in Esophageal Carcinoma

    SciTech Connect

    McQueen, A. S.; Eljabu, W.; Latimer, J. Raju, P. P. J.

    2011-02-15

    The role of metallic stents in the palliation of esophageal cancer is well established. Self-expanding metal stents (SEMSs) are frequently used, as they provide an effective and safe method of relieving malignant dysphagia. A number of complications are associated with the use of SEMSs, including esophageal perforation. We report a case of thoracic discitis occurring in a patient with advanced esophageal malignancy, treated with SEMSs. We propose that the likely etiology in this patient was esophageal perforation by a metallic stent.

  5. Status and Literature Review of Self-Expandable Metallic Stents for Malignant Colorectal Obstruction

    PubMed Central

    Cheung, Dae Young; Lee, Yong Kook

    2014-01-01

    Use of colorectal stents has increased dramatically over the last decades. Colorectal stents offer an alternative way to relieve fatal intestinal obstruction and can take place of emergency surgery, which associated with significant morbidity and mortality and a high incidence of stoma creation, to elective resection. Although there remain a few concerns regarding the use of stents as a bridge to surgical resection, use of self-expandable metallic stents for palliation in patients with unresectable disease has come to be generally accepted. Advantages of colorectal stents include acute restoration of luminal patency and allowance of time for proper staging and surgical optimization, and the well-known disadvantages are procedure-related complications including perforation, migration, and stent failure. General indications, procedures, and clinical outcomes as well as recent evidences regarding the use of colorectal stents will be discussed in this review. PMID:24570885

  6. Management of cervical esophageal strictures with self-expanding metalic stents.

    PubMed

    Cindoruk, Mehmet; Karakan, Tarkan

    2006-12-01

    Esophageal strictures due to malignant diseases are treated with self-expanding metalicic stents. However, experience is limited with these metalic stents in the cervical esophagus. Due to technical difficulties and procedure-related complications, the cervical esophagus has been assigned as a risky area for stenting procedures. Another encountered problem is patient discomfort after the procedure. In this case report, we present three patients with cervical esophageal strictures who were successfully treated with self-expandable metalic stents. Two of these patients had inoperable esophageal carcinoma and the third had benign stenosis due to radiotherapy of larynx carcinoma. The two patients with malignant disease survived four and six months, respectively, after the procedure. The last patient with benign disease is still alive and has been without dysphagia symptom for six months.

  7. Self-Expandable Metal Stenting of Refractory Upper Gut Corrosive Strictures: A New Role for Endoscopy?

    PubMed Central

    Manta, Raffaele; Conigliaro, Rita; Bertani, Helga; Manno, Mauro; Soliman, Ahmed; Fedeli, Paolo; Bassotti, Gabrio

    2011-01-01

    Caustic strictures of the gastrointestinal tract are often difficult to treat, since relapses are frequent after medical or endoscopic treatment. Thus, novel approaches are needed. We report here our experience with self-expandable metallic stents (SEMS) as a new endoscopic approach in three patients with corrosive strictures of the upper gastrointestinal tract. PMID:22606415

  8. Clinical effect of double coaxial self-expandable metallic stent in management of malignant colon obstruction

    PubMed Central

    Won, Yoodong; Lee, Su Lim; Ku, Young Mi; Kim, Ki Tae; Won, Hye Sung; An, Chang Hyeok

    2015-01-01

    PURPOSE We aimed to evaluate the clinical effectiveness and safety of double coaxial self-expandable metallic stent (DCSEMS) in management of malignant colonic obstruction as a bridge to surgery or palliation for inoperable patients. METHODS Between April 2006 and December 2012, 49 patients (27 males and 22 females; median age, 68 years; age range, 38–91 years) were selected to receive decompressive therapy for malignant colonic obstruction by implanting a DCSEMS. Application of DCSEMS was attempted in 49 patients under fluoroscopic guidance. The obstruction was located in the transverse colon (n=2), descending colon (n=7), sigmoid colon (n=24), rectosigmoid junction (n=6), and the rectum (n=10). The intended use of DCSEMS was as a bridge to elective surgery in 23 patients and palliation in 26 patients. RESULTS Clinical success, defined as >50% dilatation of the stent with subsequent symptomatic improvement, was achieved in 48 of 49 patients (98%). The stent was properly inserted in all patients. No immediate major procedure-related complications occurred. One patient in the bridge-to-surgery group had colon perforation three days after DCSEMS application. Four patients had late migrations of the double stent. CONCLUSION Application of DCSEMS is safe and effective in management of malignant colonic obstruction; it prevents stent migration and tumor ingrowth and lowers perforation rate during the stent application. PMID:25698096

  9. Efficacy of laser photoablative therapy and expandable metal stents for esophageal carcinoma

    NASA Astrophysics Data System (ADS)

    Balachandar, Gowra; Trowers, Eugene A.

    2000-05-01

    Malignant dysphagia is a serious condition in which 70% of patients die within one year, regardless of the treatment received. It provokes a rapid deterioration of a patient's physical condition and a significant worsening of quality of life. The surgical treatment of dysphagia is frequently complicated with technical difficulties, and often the tumors cannot be excised because of extensive invasion into adjacent structures. Furthermore, many patients are considered inoperable due to advanced age, associated diseases and malnutrition. Laser photoablative therapy coupled with expandable metal stents restores luminal patency in more than 80% of patients allowing them to eat liquids and soft foods. The efficacy of laser photoablative therapy and expandable metal stents for the palliation esophageal carcinoma will be critically reviewed.

  10. Safety and efficacy of self-expandable metallic stents in malignant small bowel obstructions

    PubMed Central

    Tsuboi, Akiyoshi; Kuwai, Toshio; Nishimura, Tomoyuki; Iio, Sumio; Mori, Takeshi; Imagawa, Hiroki; Yamaguchi, Toshiki; Yamaguchi, Atsushi; Kouno, Hirotaka; Kohno, Hiroshi

    2016-01-01

    In this report, we present 3 cases of malignant small bowel obstruction, treated with palliative care using endoscopic self-expandable metallic stent (SEMS) placement, with the aim to identify the safety and efficacy of this procedure. Baseline patient characteristics, procedure methods, procedure time, technical and clinical success rates, complications, and patient outcomes were obtained. All 3 patients had pancreatic cancer with small bowel strictures. One patient received the SEMS using colonoscopy, while the other 2 patients received SEMS placement via double balloon endoscopy using the through-the-overtube technique. The median procedure time was 104 min. The technical and clinical success rates were 100%. Post-treatment, obstructive symptoms in all patients improved, and a low-residue diet could be tolerated. All stents remained within the patients until their deaths. The median overall survival time (stent patency time) was 76 d. SEMS placement is safe and effective as a palliative treatment for malignant small bowel obstruction. PMID:27833393

  11. Small caliber covered self-expanding metal stents in the management of malignant dysphagia

    PubMed Central

    Kucera, Stephen; Barthel, James; Klapman, Jason; Shridhar, Ravi; Hoffe, Sarah; Harris, Cynthia; Almhanna, Khaldoun

    2016-01-01

    Background Use of large caliber [≥18 mm body diameter (BD)] self-expanding metal stents (SEMS) for management of malignant dysphasia is associated with substantial adverse event (AE) and mortality rates (MRs). We sought to determine dysphagia response, stent migration rates, and AE and MRs, for small caliber covered SEMS (sccSEMS) with BDs between 10–16 mm in malignant dysphagia. Methods Thirty-one patients underwent direct endoscopic placement of 50 sccSEMS between January 2008 and March 2011. Patients were monitored for change in dysphagia score (DS), stent migration, AEs, and death through May 2011. Results DS improved in 30 of 31 patients (97%). The median DS decreased from 3 to 2 (P<0.0001). The median effective duration of first sccSEMS placement was 116 (95% CI: 75–196) days. Major and minor AE rates were 6.5% and 19.4% respectively. No stent related deaths were encountered. The overall migration rate was 36% (18/50). The anticipated migration rate was 45.7% (16/35) and the unanticipated migration rate was 13.3% (2/15) (P=0.052). Positive effective clinical outcome occurred in 93.5% (29/31) of cases. Conclusions In malignant dysphagia, direct endoscopic sccSEMS placement provided acceptable dysphagia control and migration rates with substantial reductions in stent related AEs and MRs compared to those reported for large caliber SEMS. PMID:27284474

  12. Self-Expanding Metal Stenting in the Management of a Benign Colonic Stricture

    PubMed Central

    Jessamy, Kegan; Ozden, Nuri; Simon, Howard M.; Kobrossi, Semaan; Ubagharaji, Ezinnaya

    2016-01-01

    Colonic postanastomotic strictures occur in 1.5–8% of patients following colorectal surgery. Traditionally, colonic strictures were treated by multiple modalities including endoscopic dilatation. Self-expanding metal stents (SEMS) have been indicated in the management of benign colonic strictures; however, there are limited available data with regard to their efficacy. We present the case of a 68-year-old male who had perforated sigmoid diverticulitis followed by Hartmann's procedure with eventual reanastomosis 6 months later. He subsequently developed benign colonic stricture, which was treated with a metal stent. SEMS are associated with a low mortality rate and are appropriate in treating acute colonic obstruction as a result of benign stricture in the setting of postanastomosis. PMID:27403114

  13. Comparison of Endoscopic Vacuum Therapy and Endoscopic Stent Implantation With Self-Expandable Metal Stent in Treating Postsurgical Gastroesophageal Leakage

    PubMed Central

    Hwang, Jae J.; Jeong, Yeon S.; Park, Young S.; Yoon, Hyuk; Shin, Cheol M.; Kim, Nayoung; Lee, Dong H.

    2016-01-01

    Abstract The aim of the present study was to evaluate the more effective therapy for the postsurgical gastroesophageal leakage by a head-to-head comparison of endoscopic vacuum therapy (EVT) and endoscopic stent implantation with self-expandable metal stent (E-SEMS). In this hospital-based, retrospective, observative study, the patients were classified into 2 groups. Those treated with EVT were assigned to the EVT group (n = 7), and those treated with E-SMS were assigned to the E-SEMS group (n = 11). We evaluated the clinical characteristics and treatment outcomes between the 2 groups. All 7 patients (100%) were treated with EVT, but only 7 of 11 patients (63.6%) in the stenting group were treated successfully. The median time to clinical success was 19.5 (5–21) days in the EVT group and 27.0 (3–84) days in the E-SEMS group. The median hospital stay was 37.1 (13–128) days in the EVT group and 87.3 (17–366) days in the E-SEMS group. The complicaion rate was lower in the EVT group (0/7, 0.0%) than that in the E-SEMS group (6/11, 54.5%) with statistically significant difference (P = 0.042). EVT is more effective and has fewer adverse effects than E-SMS therapy as a treatment for postsurgical gastroesophageal leakage. PMID:27100431

  14. Comparison of Endoscopic Vacuum Therapy and Endoscopic Stent Implantation With Self-Expandable Metal Stent in Treating Postsurgical Gastroesophageal Leakage.

    PubMed

    Hwang, Jae J; Jeong, Yeon S; Park, Young S; Yoon, Hyuk; Shin, Cheol M; Kim, Nayoung; Lee, Dong H

    2016-04-01

    The aim of the present study was to evaluate the more effective therapy for the postsurgical gastroesophageal leakage by a head-to-head comparison of endoscopic vacuum therapy (EVT) and endoscopic stent implantation with self-expandable metal stent (E-SEMS). In this hospital-based, retrospective, observative study, the patients were classified into 2 groups. Those treated with EVT were assigned to the EVT group (n = 7), and those treated with E-SMS were assigned to the E-SEMS group (n = 11). We evaluated the clinical characteristics and treatment outcomes between the 2 groups. All 7 patients (100%) were treated with EVT, but only 7 of 11 patients (63.6%) in the stenting group were treated successfully. The median time to clinical success was 19.5 (5-21) days in the EVT group and 27.0 (3-84) days in the E-SEMS group. The median hospital stay was 37.1 (13-128) days in the EVT group and 87.3 (17-366) days in the E-SEMS group. The complicaion rate was lower in the EVT group (0/7, 0.0%) than that in the E-SEMS group (6/11, 54.5%) with statistically significant difference (P = 0.042). EVT is more effective and has fewer adverse effects than E-SMS therapy as a treatment for postsurgical gastroesophageal leakage.

  15. Endosonography-guided drainage of malignant fluid collections using lumen-apposing, fully covered self-expanding metal stents.

    PubMed

    Musumba, Crispin; Tutticci, Nicholas; Nanda, Kavinderjit; Kwan, Vu

    2014-08-01

    Endosonography (EUS)-guided drainage of paragastric fluid collections using fully covered self-expanding metal stents (FCSEMS) is now a well-established procedure. Recently, new and specially designed lumen-apposing, fully-covered metal cystgastrostomy stents have been employed for this indication. In this case series, the use of these new stents for the drainage of malignant fluid collections in three symptomatic patients is described. Cases included a large pancreatic pseudocyst, secondary to underlying acute lymphoblastic leukemia, and two large collections of loculated ascites due to metastatic ovarian and cervical cancer, respectively. Technical success in inserting the new stents was achieved in all three patients, and resulted in symptomatic relief. There were no clinically significant complications directly attributed to the stents. These new lumen-apposing cystgastrostomy stents may provide a viable, minimally invasive, and effective alternative for drainage of malignant fluid collections, either for definitive treatment or for palliation of symptoms.

  16. Tracheobronchial tree: expandable metallic stents used in experimental and clinical applications. Work in progress.

    PubMed

    Wallace, M J; Charnsangavej, C; Ogawa, K; Carrasco, C H; Wright, K C; McKenna, R; McMurtrey, M; Gianturco, C

    1986-02-01

    An expandable stainless steel stent was formulated for use in the treatment of tracheobronchial stenosis, tracheomalacia, and airway collapse following tracheal reconstruction. The stents were placed through an endotracheal tube into the trachea and bronchi of 11 healthy dogs. The stents expanded over time, substantially increasing the diameter of the lumen. Slight migration occasionally occurred, while an inflammatory reaction was noted in each animal. The stents were successfully used in the treatment of two cancer patients to dilate a postoperative bronchial stenosis that caused pneumonia and to support a tracheal graft that collapsed with respiration. Because of the stent migration in experimental studies, designs are being tested to develop stents with greater stability. These stents may be effective in overcoming stenosis caused by scarring, extrinsic compression, and collapse of reconstructed tracheobronchial structures.

  17. Arterial bleeding during EUS-guided pseudocyst drainage stopped by placement of a covered self-expandable metal stent

    PubMed Central

    2013-01-01

    Background Hemorrhagic complications during EUS-guided pseudocyst drainage can occur, because the vessels on the internal wall of the pseudocyst might be compressed by the fluid and thus not visible on color Doppler or even power Doppler EUS. Case presentation We report a case of an immediate internal spurting arterial bleeding precipitated during EUS-guided pseudocyst drainage which stopped instantaneously by placement of a double flanged covered self-expandable metal stent through mechanical hemostasis. Conclusion In an unusual situation of bleeding from collateral circulation near the pseudocyst wall during pseudocyst drainage, the placement of an expandable metal stent proved to be useful. PMID:23706101

  18. A fully covered self-expandable metal stent anchored by a 10-Fr double pigtail plastic stent: an effective anti-migration technique

    PubMed Central

    Katsinelos, Panagiotis; Lazaraki, Georgia; Gkagkalis, Stergios; Chatzimavroudis, Grigoris; Anastasiadou, Kiriaki; Georgakis, Nikos; Giouleme, Olga; Zavos, Christos; Kountouras, Jannis

    2017-01-01

    Background Fully covered self-expandable metal stents (FCSEMS) have been used successfully in the treatment of malignant and benign biliary strictures. However, stent migration is a major complication. We investigated the efficacy of anchoring FCSEMS with a 10-Fr double-pigtail plastic stent to prevent migration in patients with biliary strictures. Methods Between January 2012 and May 2013, 10 patients with malignant biliary strictures and one patient with a suprapapillary benign biliary stenosis were enrolled in the study. The primary endpoint of the study was to record the migration rate of FCSEMS. Results The placement of FCSEMSs and the anchoring with a 10-Fr double-pigtail plastic stent were successful in all patients. During a median follow-up period of eight months, proximal or distal migration of FCSEMS was not observed. No procedural complications related to the placement of FCSEMS and/or the anchoring plastic stent were recorded. Conclusions The placement of an anchoring 10-Fr double-pigtail stent is a simple and effective anti-migration technique for FCSEMS in patients with malignant biliary strictures. PMID:28042247

  19. Bronchoscopic management of critical central airway obstruction by thyroid cancer: Combination airway stenting using tracheal and inverted-Y carinal self-expanding metallic stents

    PubMed Central

    Madan, Karan; Shrestha, Prajowl; Garg, Rakesh; Hadda, Vijay; Mohan, Anant; Guleria, Randeep

    2017-01-01

    Central airway obstruction (CAO) can result from various benign and malignant etiologies. Anaplastic thyroid cancer (ATC) is the most aggressive form of thyroid cancer. Rapid airway compromise is the main cause of death in ATC. We report a patient with ATC who presented with a large neck mass leading to CAO with long segment tracheal and right main bronchial compression and respiratory failure. Urgent Rigid Bronchoscopy was performed for airway stabilization and patient was managed with a combination airway stenting approach. A combination of self expanding, metallic, covered inverted Y and straight tracheal stents was used to stabilize the near complete airway structure. We herein highlight the role of therapeutic rigid bronchoscopy with airway stenting as an efficacious treatment modality for management of malignant CAO. PMID:28360477

  20. Palliation of Obstructing Malignant Colonic Lesions Using Self-Expanding Metal Stents: A Single-Center Experience

    SciTech Connect

    Shrivastava, Vivek; Tariq, Omar; Tiam, ReeNee; Nyhsen, Christiane; Marsh, Ralph

    2008-09-15

    To evaluate the efficacy, risks, and survival after palliative colorectal stenting at a single center, we conducted a retrospective review of consecutive patients who had colorectal self-expanding metal stents (SEMSs) inserted over an 8-year period (September 1998 to September 2006) to relieve an obstructing colorectal tumor. All patients either had proven distant metastases or were unfit for surgical decompression. A single interventional radiologist (R.M.) inserted the stents, which were either Memotherm or WallFlex. Ninety-one patients with a median age of 73 years had a colorectal stent inserted for palliation of an obstructing colorectal malignancy. Technical success was achieved in 81 of 91 (89%) patients, and clinical success in 80 of 81 (99%). At the time of analysis (December 2006), 13 of 91 (14.2%) patients were alive. The patients who died had a median survival of 59 days, IQR 17-181 days. Seven (7/81) patients suffered stent migration, which occurred 10.3 days (IQR, 5-14 days) after the procedure. Three patients (3/81) re-presented with intestinal obstruction secondary to tumor ingrowth and 10 (10.9%) patients suffered bowel perforation. Ten patients (10.9%) had two stents inserted coaxially and overlapping in one procedure. This was performed in cases where the stricture was too long to be easily crossed by a single stent. We conclude that colorectal SEMS is a safe and effective mode of treatment for the palliation of obstructing colorectal cancers, which avoids high-risk surgery.

  1. Self-expandable metal stents for obstructing colonic and extracolonic cancer: European Society of Gastrointestinal Endoscopy (ESGE) Clinical Guideline.

    PubMed

    van Hooft, Jeanin E; van Halsema, Emo E; Vanbiervliet, Geoffroy; Beets-Tan, Regina G H; DeWitt, John M; Donnellan, Fergal; Dumonceau, Jean-Marc; Glynne-Jones, Robert G T; Hassan, Cesare; Jiménez-Perez, Javier; Meisner, Søren; Muthusamy, V Raman; Parker, Michael C; Regimbeau, Jean-Marc; Sabbagh, Charles; Sagar, Jayesh; Tanis, Pieter J; Vandervoort, Jo; Webster, George J; Manes, Gianpiero; Barthet, Marc A; Repici, Alessandro

    2014-11-01

    This Guideline is an official statement of the European Society of Gastrointestinal Endoscopy (ESGE). This Guideline was also reviewed and endorsed by the Governing Board of the American Society for Gastrointestinal Endoscopy (ASGE). The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was adopted to define the strength of recommendations and the quality of evidence. Main recommendations The following recommendations should only be applied after a thorough diagnostic evaluation including a contrast-enhanced computed tomography (CT) scan. 1 Prophylactic colonic stent placement is not recommended. Colonic stenting should be reserved for patients with clinical symptoms and imaging evidence of malignant large-bowel obstruction, without signs of perforation (strong recommendation, low quality evidence). 2 Colonic self-expandable metal stent (SEMS) placement as a bridge to elective surgery is not recommended as a standard treatment of symptomatic left-sided malignant colonic obstruction (strong recommendation, high quality evidence). 3 For patients with potentially curable but obstructing left-sided colonic cancer, stent placement may be considered as an alternative to emergency surgery in those who have an increased risk of postoperative mortality, I. e. American Society of Anesthesiologists (ASA) Physical Status ≥ III and/or age > 70 years (weak recommendation, low quality evidence). 4 SEMS placement is recommended as the preferred treatment for palliation of malignant colonic obstruction (strong recommendation, high quality evidence), except in patients treated or considered for treatment with antiangiogenic drugs (e. g. bevacizumab) (strong recommendation, low quality evidence).

  2. Self-expanding metal mesh stents and laser therapy: a complementary approach for the palliation of malignant dysphagia

    NASA Astrophysics Data System (ADS)

    Madhotra, Ravi; Raouf, A.; Sturgess, R.; Krasner, Neville

    1997-12-01

    Re-establishment of the oesophageal lumen is the main focus of care in patients with inoperable oesophageal carcinomas. The self-expanding metal mesh stents (MMS) are increasingly being used. 51 patients aged 44 - 89 with inoperable oesophago-gastric carcinomas were intubated with MMS. 18 of these patients had endoscopic laser therapy (ELT) as primary palliation. 25 patients required follow-up endoscopy at variable intervals after stent insertion. 17 patients were found to have significant tumor growth (9), overgrowth (4) and both (4). All these patients were treated with Nd:YAG or diode laser for maintenance of satisfactory swallowing. 4 patients being treated with Nd:YAG laser developed deformity of MMS. This complication was not encountered with diode laser. The reblockage of MMS due to ingrowth or overgrowth of tumor is a not uncommon complication. The timing of the stent insertion should be carefully chosen since the longer the stent is in situ, the greater is the likelihood of tumor ingrowth or overgrowth. ELT can effectively deal with tumor ingrowth and overgrowth. Nd:YAG laser can cause melting of MMS. Overall the combination of ELT and MMS may offer the best palliation, particularly when patient survival of several months is anticipated.

  3. Y-Shaped Bilateral Self-Expandable Metallic Stent Placement for Malignant Hilar Biliary Obstruction: Data from a Referral Center for Palliative Care

    PubMed Central

    Di Mitri, R.; Mocciaro, F.

    2014-01-01

    Background and Aim. Malignant hilar strictures are a clinical challenge because of the current therapeutic approach and the poor prognosis. In recent years, self-expandable metallic stents have proven more effective than plastic stents for palliation of malignant hilar strictures, with the bilateral stent-in-stent technique registering a high success rate. We report our experience with Y-shaped endoscopic self-expandable metallic stents placement for treatment of advanced malignant hilar strictures. Methods. From April 2009 to August 2012, we prospectively collected data on patients treated with Y-shaped SEMS placement for advanced malignant hilar carcinoma. Data on technical success, clinical success, and complications were collected. Results. Twenty patients (9 males) were treated (mean age 64.2 ± 15.3 years). The grade of malignant hilar strictures according to the Bismuth classification was II in 5 patients (25%), IIIa in 1 (5%), and IV in 14 (70%). The mean bilirubin level was 14.7 ± 4.9 mg/dL. Technical success was achieved in all patients, with a significant reduction in bilirubin levels (2.9 ± 1.7 mg/dL). One patient experienced cholangitis as early complication, while in 2 patients stent ingrowth was observed. No stents migration was recorded. There was no procedure-related mortality. At the end of the follow-up (7.1 ± 3.1 months), 13 of the 20 patients (65%) had died. Conclusions. Our experience confirms endoscopic bilateral self-expandable metallic stents placement with stent-in-stent technique (Y-shaped configuration) as a feasible, effective, and safe procedure for palliation of unresectable malignant hilar strictures. PMID:24790548

  4. Analytical Models for Predicting Mechanical Properties of Self-Expandable Metal Stents with Cover Membrane

    DTIC Science & Technology

    2007-11-02

    compressed, it elongates in its longitudinal direction. Consider the deformation of parallelogram cell as shown in Fig. 4(A). When the points A, B, and...the cell maintains a parallelogram shape during compression. The length between A and B of uncompressed stent is N klL wireAB 0 sin2 β= (14...Expansive pressure- deformation curve for bare type stent. 8 10 12 14 16 0 4 8 12 16 Experiments Pbare Pcoat Pcoated stent

  5. Placement of a new fully covered self-expanding metal stent for postoperative biliary strictures and leaks not responding to plastic stenting.

    PubMed

    Luigiano, Carmelo; Bassi, Marco; Ferrara, Francesco; Fabbri, Carlo; Ghersi, Stefania; Morace, Carmela; Consolo, Pierluigi; Maimone, Antonella; Galluccio, Gabriella; D'Imperio, Nicola; Cennamo, Vincenzo

    2013-04-01

    Fully covered self-expanding metal stents (FCSEMSs) are now being used to treat postoperative biliary strictures (BSs) and biliary leaks (BLs). The aim of this study was to assess the safety and effectiveness of a new FCSEMS (Wallflex) in patients with postoperative BSs and BLs after failure of traditional endoscopic treatment. Between January 2010 and December 2011, 16 patients (10 patients with postcholecystectomy BSs, 4 with postcholecystectomy BLs, and 2 with postorthotopic liver transplantation BSs) were enrolled. The technical and clinical success rate was 100%. All FCSEMSs were removed after a mean of 141 days. Complications occurred in 7 cases: 2 postprocedure pain, 2 mild pancreatitis, 1 early distal, and 2 late proximal FCSEMS migration. The overall long-term clinical success rate was 94% after a mean follow-up of 13 months. In our experience, the placement of FCSEMSs is an effective and secure method of treating refractory postoperative BSs or BLs.

  6. Antireflux versus conventional self-expanding metallic Stents (SEMS) for distal esophageal cancer: results of a multicenter randomized trial

    PubMed Central

    Coron, E.; David, G.; Lecleire, S.; Jacques, J.; Le Sidaner, A.; Barrioz, T.; Coumaros, D.; Volteau, C.; Vedrenne, B.; Bichard, P.; Boustière, C.; Touchefeu, Y.; Brégeon, J.; Prat, F.; Le Rhun, M.

    2016-01-01

    Introduction: Self-expanding metal stents (SEMS) are commonly used in the palliation of dysphagia in patients with inoperable esophageal carcinoma. However, they predispose to gastroesophageal reflux when deployed across the gastroesophageal junction. The aims of this study were to: 1) assess the influence of the antireflux valve on trans-prosthetic reflux (primary outcome); and 2) compare the results of SEMS with and without antireflux valve in terms of reflux symptoms, quality of life (QOL), improvement of dysphagia and adverse events (secondary outcomes). Patients and methods: Thirty-eight patients were enrolled in nine centers. Carcinomas were locally advanced (47 %) or metastatic. After randomization, patients received either a covered SEMS with antireflux valve (n = 20) or a similar type of SEMS with no antireflux device but assigned to standard proton pump inhibitor therapy and postural advice (n = 18). Trans-prosthetic reflux was assessed at day 2 using a radiological score based on barium esophagography performed after Trendelenburg maneuver and graded from 0 (no reflux) to 12 (maximum). Monthly telephone interviews were conducted for Organisation Mondiale de la Santé (OMS) scoring from 0 (excellent) to 5 (poor), QOL assessment (based on the Reflux-Qual Simplifié scoring system) from 0 (poor) to 100 (excellent), dysphagia scoring from 0 (no dysphagia) to 5 (complete dysphagia) and regurgitation scoring from 0 (no regurgitation) to 16 (maximum). Results: No difference was noted in terms of age, sex, size of lesion, prosthesis length or need for dilation prior to SEMS placement. No difficulty in placing SEMS nor complications were noted. Radiological scores of reflux were found to be significantly lower in patients with an antireflux stent compared to the conventional stent and associated measures. The regurgitation scores were significantly decreased in patients with antireflux stents during the first 2 months after stent placement and

  7. Self-Expanding Metal Stents for Palliative Treatment of Superior Vena Caval Syndrome

    SciTech Connect

    Oudkerk, Matthijs; Kuijpers, Theodore J.A.

    1996-05-15

    Purpose: Two stent types (a new Wallstent and a Z-stent) were investigated in 30 patients with recurrent malignant superior vena caval syndrome (SVCS). Methods: Eligibility requirements were that the patient had recurrent symptoms after appropriate radiation therapy, chemotherapy, or both; {>=}75% of the vessel was occluded; and there was collateral flow. Because of the limited availability of stents, it was not possible to perform a prospectively randomized study. Results: In the Z-stent group (17 patients), occlusion of the stent due to acute thrombosis occurred within 12 hr in 4 patients (24%), but in the other 13 patients (76%) symptoms disappeared completely. After 2 weeks the cavogram in these patients showed no signs of thrombosis, and 12 (71%) of the patients remained symptom-free. There was partial occlusion in 5 patients (29%), without relevant clinical symptoms. Of the 13 patients who received Wallstents, only 1 had an acute immediate thrombosis (8%). Symptoms disappeared completely in the other 12 patients and no signs of thrombosis were seen. However, after 2 weeks complete stent occlusion with SVCS was found in 3 patients (23%) and partial occlusion with minor clinical symptoms in 6 (46%). Only 3 patients (23%) had complete relief of their SVCS. The difference between the rates of occlusion of the two stents after 2 weeks was highly significant (p= 0.008). Conclusions: The overall clinical success rate for long-term patency was 100% for the Z-stents and 69% for the new Wallstent. These results suggest that when used for this purpose, the new Wallstent is more thrombogenic at 2 weeks than the Z-stent.

  8. Salvage therapy using self-expandable metal stents for recalcitrant anastomotic strictures after living-donor liver transplantation

    PubMed Central

    Jang, Sung Ill; Sung, Se Yong; Park, Hyunsung; Lee, Kwang-Hun; Joo, Seung-Moon; Lee, Dong Ki

    2017-01-01

    Background: Recently, there has been an increase in clinical success rates using nonsurgical methods to resolve anastomotic biliary strictures (ABSs) that develop after liver transplantation (LT). However, some strictures are particularly refractory and cannot be completely resolved by an endoscopic or percutaneous procedure. Consequently, the aim of this study was to examine the feasibility and efficacy of using a newly designed fully covered self-expandable metal stent (FCSEMS) to resolve refractory ABS. Methods: A total of 35 patients with an ABS that developed after LT, but could not be resolved by an endoscopic or percutaneous procedure, were included in this study. FCSEMSs were positioned endoscopically and removed after 2–3 months. After stent removal, the patients were followed to assess complications, including re-stenosis. Results: The mean period from LT to stricture was 13.7 months, and the mean duration of the stricture was 31.8 months. The type and mean number of procedures previously attempted were endoscopic retrograde cholangiopancreatography (ERCP) (9.1 ± 5.1) in 19 patients and percutaneous transhepatic biliary drainage (9.2 ± 4.8) in 16 patients. All patients had successful FCSEMS insertions and removals; the mean stent indwelling time was 3.2 months. The mean follow-up period was 18.7 months (range: 6.4–37.8 months). Stricture recurrence was observed in 6 of 29 patients (recurrence rate: 20.7%). The anastomotic stricture resolved with the FCSEMS insertion in 29 of 35 patients (clinical success rate: 82.9%). Conclusions: The newly designed FCSEMS is a potentially feasible and effective treatment for anastomotic strictures that develop after LT but are not amenable to treatment by conventional procedures. PMID:28246547

  9. Self-expanding metal stents for the palliation of malignant gastric outlet obstruction in patients with peritoneal carcinomatosis

    PubMed Central

    Rademacher, Christoph; Bechtler, Matthias; Schneider, Steffen; Hartmann, Bettina; Striegel, Johannes; Jakobs, Ralf

    2016-01-01

    AIM To evaluate the efficacy of self-expanding metal stents (SEMS) for the palliation of malignant gastric outlet obstruction in patients with and without peritoneal carcinomatosis (PC). METHODS We performed a retrospective analysis of 62 patients who underwent SEMS placement for treatment of malignant gastroduodenal obstruction at our hospital over a six-year period. Stents were deployed through the scope under combined fluoroscopic and endoscopic guidance. Technical success was defined as successful stent placement and expansion. Clinical success was defined as an improvement in the obstructive symptoms and discharge from hospital without additional parenteral nutrition. According to carcinomatosis status, patients were assigned into groups with or without evidence of peritoneal disease. RESULTS In most cases, obstruction was caused by pancreatic (47%) or gastric cancer (23%). Technical success was achieved in 96.8% (60/62), clinical success in 79% (49/62) of all patients. Signs of carcinomatosis were identified in 27 patients (43.5%). The diagnosis was confirmed by pathology or previous operation in 7 patients (11.2%) and suspected by CT, MRI or ultrasound in 20 patients (32.2%). Presence of carcinomatosis was associated with a significantly lower clinical success rate compared to patients with no evidence of peritoneal disease (66.7% vs 88.6%, P = 0.036). There was no significant difference in overall survival between patients with or without PC (median 48 d vs 70 d, P = 0.21), but patients showed significantly longer survival after clinical success of SEMS placement compared to those experiencing clinical failure (median 14.5 d vs 75 d, P = 0.0003). CONCLUSION Given the limited therapeutic options and a clinical success rate of at least 66.7%, we believe that SEMS are a reasonable treatment option in patients with malignant gastric outlet obstruction with peritoneal carcinomatosis. PMID:27920476

  10. Reocclusion after Self-Expandable Metallic Stent Placement for Relieving Malignant Colorectal Obstruction as a Palliative Treatment

    PubMed Central

    Nitta, Toshikatsu; Fujii, Kensuke; Hirata, Yoshimasa; Tominaga, Tomo; Inoue, Yoshihiro; Kawasaki, Hiroshi; Kawakami, Ken; Ishibashi, Takashi

    2016-01-01

    Self-expandable metallic stent (SEMS) placement has been practiced in several hospitals in Japan, including ours, since January 2012. Here, we report the case of an 82-year-old Japanese man who presented to the hospital with a 1-week history of right hypochondrial pain. Computed tomography (CT) findings indicated colorectal cancer. The laboratory findings on admission indicated severe anemia (red blood cell count, 426 × 104/μL; hemoglobin, 7.9 g/dL). We performed SEMS placement because the patient refused to undergo surgery. He did not attend any of the scheduled follow-up visits after SEMS placement. However, a year and a half after the SEMS placement, the patient attended the hospital because of difficulty in passing stool. A plain abdominal CT scan showed bowel reobstruction due to the ascending colon cancer after SEMS placement. We performed an emergency operation, ascending colostomy, on the same day. Colorectal stent placement may be a good treatment option for patients who refuse to undergo conventional therapeutic treatments or in those with unresectable colorectal cancer. Patients should be carefully followed up every few months after SEMS placement because of the risk of reocclusion. PMID:28100994

  11. Anatomy-shaped design of a fully-covered, biliary, self-expandable metal stent for treatment of benign distal biliary strictures

    PubMed Central

    Weigt, Jochen; Kandulski, Arne; Malfertheiner, Peter

    2016-01-01

    Background and study aims: The treatment success of benign biliary strictures with fully covered metal stents (CSEMS) is altered by high stent dislocation rates. We aimed to evaluate a new stent design to prevent dislocation. Patients and methods: Patients with benign biliary strictures were treated with a newly designed double-coned stent (dcSEMS). Mechanical analysis of the new stent was performed and it was compared with a cylindrical stent. Results: A total of 13 dcCSEMS were implanted in 11 patients (2 female, 9 male, median age 47, range 33 – 71). All patients had distal biliary strictures due to chronic pancreatitis. No stent migration occurred. In all but one patient the stents were removed. One patient refused stent extraction and was lost to follow up. Stent occlusion occurred twice leading to cholangitis in both cases. The duration of stent treatment was 170 days (range 61 – 254). After extraction only one patient had early recurrent stricture and received the same stent again. Three stents showed minimal tissue granulation at the papilla. One stent presented ingrowth at the proximal end and was removed after implantation of a second fully covered stent. Mechanical examination revealed significantly lower radial expansion force of the new stent as compared to the cylindrical stent. Conclusions: The new stent design has a low rate of migration. Biomechanical properties may explain this effect. PMID:26793789

  12. Percutaneous cholangioscopy in obstructed biliary metal stents

    SciTech Connect

    Hausegger, Klaus A.; Mischinger, Hans J.; Karaic, Radenko; Klein, Guenther E.; Kugler, Cristian; Kern, Robert; Uggowitzer, Martin; Szolar, Dieter

    1997-05-15

    Purpose. To reevaluate the reasons for the occlusion of self-expanding biliary metal stents, on the basis of cholangioscopic findings. Methods. Percutaneous transhepatic cholangioscopy (PTCS) was performed in 15 patients with obstructed biliary Wallstents. The reason for stent insertion was a malignant obstruction in 14 patients; 1 had a benign biliary stricture. Conventional noncovered stents had been inserted in 12 patients; in 3 cases a polyurethane-covered prototype Wallstent had been used. Stent occlusions occurred after 1-55 months. PTCS was performed with a 2.3-mm endoscope through an 11 Fr sheath. Biopsies were taken via the working channel of the endoscope. Results. In all patients with noncovered stents the inner surface of the stent was highly irregular with seaweed-like protrusions (biopsy-proven granulation tissue). Stent incorporation varied from absent (n=1) to subtotal (n=8), but was always incomplete, no matter how long the stent had been in place. Tumor ingrowth was histologically proven in 2 patients. One patient had a large occluding concrement at the proximal end of the stent. In patients with covered stents, the inner surface appeared more regular; however, viable granulation tissue was found inside two stents and tumor ingrowth in one of them. Conclusion. PTCS showed that incorporation of the stent is virtually always incomplete. The factors contributing most to stent occlusion are the buildup of granulation tissue, bile sludge, and tumor overgrowth. Stone formation and tumor ingrowth can also be important, although less common causes of occlusion. A polyurethane stent covering could not prevent tumor ingrowth in one patient and the buildup of viable granulation tissue inside the stent in two further patients; mean stent patency in the three patients with such a stent was 3 months.

  13. Efficacy and safety of limited endoscopic sphincterotomy before self-expandable metal stent insertion for malignant biliary obstruction

    PubMed Central

    Nam, Hyeong Seok; Kang, Dae Hwan; Kim, Hyung Wook; Choi, Cheol Woong; Park, Su Bum; Kim, Su Jin; Ryu, Dae Gon

    2017-01-01

    AIM To evaluate the safety and efficacy of limited endoscopic sphincterotomy (ES) before placement of self-expandable metal stent (SEMS). METHODS This was a retrospective analysis of 244 consecutive patients with unresectable malignant biliary obstruction, who underwent placement of SEMSs following limited ES from December 2008 to February 2015. The diagnosis of malignant biliary obstruction and assessment of patient eligibility for the study was established by a combination of clinical findings, laboratory investigations, imaging and pathological results. All patients were monitored in the hospital for at least 24 h following endoscopic retrograde cholangio pancreatography (ERCP). The incidence of immediate or early post-ERCP complications such as post-ERCP pancreatitis (PEP) and bleeding related to limited ES were considered as primary outcomes. Also, characteristics and complications according to the cancer type were classified. RESULTS Among the 244 patients included, the underlying diagnosis was cholangiocarcinoma in 118 patients, pancreatic cancer in 79, and non-pancreatic or non-biliary malignancies in the remaining 47 patients. Early post-ERCP complications occurred in 9 patients (3.7%), with PEP in 7 patients (2.9%; mild, 6; moderate, 1) and mild bleeding in 2 patients (0.8%). There was no significant association between the incidence of post-ERCP complications and the type of malignancy (cholangiocarcinoma vs pancreatic cancer vs others, P = 0.696) or the type of SEMS used (uncovered vs covered, P = 1.000). Patients who had more than one SEMS placed at the first instance were at a significantly higher risk of post-ERCP complications (one SEMS vs two SEMS, P = 0.031). No other factors were predictive of post-ERCP complications. CONCLUSION Limited ES is feasible and safe, and effectively facilitates the placement of SEMS, without any significant risk of PEP or severe bleeding. PMID:28321164

  14. Correction: Prospective pilot study of fully covered self-expandable metal stents for refractory benign pancreatic duct strictures: long-term outcomes

    PubMed Central

    Matsubara, Saburo; Sasahira, Naoki; Isayama, Hiroyuki; Takahara, Naminatsu; Mizuno, Suguru; Kogure, Hirofumi; Yamamoto, Natsuyo; Nakai, Yousuke; Tada, Minoru; Koike, Kazuhiko

    2016-01-01

    Background and study aims: Background and study aims: Temporary placement of a fully covered self-expandable metal stent (FCSEMS) has recently emerged as a treatment option for pancreatic duct strictures due to chronic pancreatitis refractory to conventional plastic stenting. However, there are no data about long-term outcomes with this therapeutic option. The aims of the current study were to estimate the feasibility, safety, efficacy, and long-term outcomes of temporary FCSEMS placement for refractory pancreatic duct strictures. Patients and methods: This was a prospective, single-center feasibility study. Ten patients with refractory pancreatic duct strictures due to chronic pancreatitis underwent FCSEMS placement for 3 months. We evaluated the rate of recurrent symptoms after stent removal during long-term follow-up, as well as adverse events (AEs). Results: Two patients required early (within 1 week) stent removal because of intolerable pain or pancreatitis. In the remaining 8 patients, the recurrence rate of any symptoms after FCSEMS removal was 63% during 35 months of follow up. The causes of recurrent symptoms were as follows: recurrence of stricture in 2; stent-induced stricture in 1; impaction of pancreatic stones in 1; and development of a pseudocyst in 1. When limited to stricture, the recurrence rate was 38%. Additional endoscopic treatments were required in 4 patients: a second FCSEMS placement in 1; plastic stent (PS) placement in 1; stone extraction in 1; and endoscopic ultrasound–guided pseudocyst drainage in 1. Asymptomatic stent migration occurred in 2 patients. Suppurative pancreatic ductitis due to food impaction in the FCSEMS occurred in 2 patients, and endoscopic pancreatic duct drainage was performed. Stent-induced ductal changes developed in 2 patients and PS treatment was required in 1 patient for pain relief. Conclusion: The FCSEMS appears to be a feasible and potentially effective option for the management of refractory pancreatic duct

  15. Endoscopic radiofrequency ablation combined with fully covered self-expandable metal stent for inoperable periampullary carcinoma in a liver transplant patient

    PubMed Central

    Tian, Qing; Wang, Guijie; Zhang, Yamin; Jin, Yan; Cui, Zilin; Sun, Xiaoye; Shen, Zhongyang

    2017-01-01

    Abstract Rationale: Postliver transplant periampullary carcinoma is an extremely uncommon disease. Patient concerns: Cutaneous jaundice in a patient who had received a liver transplant 4 years earlier. Diagnosis: Periampullary carcinoma. Interventions: Radiofrequency ablation plus fully covered self-expanding metal stents (FCSEMS). Outcomes: The treatment of malignant neoplasm of the ampulla of Vater is the patient by radiofrequency ablation plus FCSEMS placement was successful. No complications occurred. Lessons: This is the first reported case of a liver transplant patient with inoperable periampullary carcinoma successfully treated by radiofrequency ablation plus FCSEMS placement. Our experience will be useful to other surgeons in managing similar patients in the future. PMID:28151854

  16. Endoscopic ultrasound-guided gallbladder drainage for acute cholecystitis: Long-term outcomes after removal of a self-expandable metal stent

    PubMed Central

    Kamata, Ken; Takenaka, Mamoru; Kitano, Masayuki; Omoto, Shunsuke; Miyata, Takeshi; Minaga, Kosuke; Yamao, Kentaro; Imai, Hajime; Sakurai, Toshiharu; Watanabe, Tomohiro; Nishida, Naoshi; Kudo, Masatoshi

    2017-01-01

    AIM To assess the long-term outcomes of this procedure after removal of self-expandable metal stent (SEMS). The efficacy and safety of endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) with SEMS were also assessed. METHODS Between January 2010 and April 2015, 12 patients with acute calculous cholecystitis, who were deemed unsuitable for cholecystectomy, underwent EUS-GBD with a SEMS. EUS-GBD was performed under the guidance of EUS and fluoroscopy, by puncturing the gallbladder with a needle, inserting a guidewire, dilating the puncture hole, and placing a SEMS. The SEMS was removed and/or replaced with a 7-Fr plastic pigtail stent after cholecystitis improved. The technical and clinical success rates, adverse event rate, and recurrence rate were all measured. RESULTS The rates of technical success, clinical success, and adverse events were 100%, 100%, and 0%, respectively. After cholecystitis improved, the SEMS was removed without replacement in eight patients, whereas it was replaced with a 7-Fr pigtail stent in four patients. Recurrence was seen in one patient (8.3%) who did not receive a replacement pigtail stent. The median follow-up period after EUS-GBD was 304 d (78-1492). CONCLUSION EUS-GBD with a SEMS is a possible alternative treatment for acute cholecystitis. Long-term outcomes after removal of the SEMS were excellent. Removal of the SEMS at 4-wk after SEMS placement and improvement of symptoms might avoid migration of the stent and recurrence of cholecystitis due to food impaction. PMID:28216973

  17. [Results of the upper digestive tract stenting with self-expanding stents].

    PubMed

    Fedorov, A G; Davydova, S V; Klimov, A E; Lebedev, N V

    2013-01-01

    The work is based on the analysis of the palliative treatment of 66 patients with malignant upper digestive tract obstruction who underwent implantation of 75 self-expanding metallic stents in the period of 2003-2012 yy. Early postoperative complications developed in 10 (15.2%) cases. Procedure-related complications were observed in 8 (12.1%) patients, non-specific complications occurred in 2 (3.0%) patients. In-hospital lethality was 4.5% (3 patients). 51 patients were followed until death. Symptomatic relapse of obstruction was observed in 4 cases. Median survival was 97 days. Stenting with self-expanding metal stents was concluded to be an effective and safe method of palliation of malignant upper digestive tract stenosis.

  18. The New Nitinol Conformable Self-Expandable Metal Stents for Malignant Colonic Obstruction: A Pilot Experience as Bridge to Surgery Treatment

    PubMed Central

    2014-01-01

    Introduction. Self-expandable metal stents (SEMS) are a nonsurgical option for treatment of malignant colorectal obstruction also as a bridge to surgery approach. The new nitinol conformable stent has improved clinical outcomes in these kinds of patients. We report a pilot experience with nitinol conformable SEMS placement as bridge to surgery treatment in patients with colorectal obstruction. Materials and Methods. Between April and August 2012, we collected data on colonic nitinol conformable SEMS placement in a cohort of consecutive symptomatic patients, with malignant colorectal obstruction, who were treated as a bridge to surgery. Technical success, clinical success, and adverse events were recorded. Results. Ten patients (7 male (70%)), with a mean age of 69.2 ± 10.1, were evaluated. The mean length of the stenosis was 3.6 ± 0.6 cm. Five patients (50%) were treated on an emergency basis. The median time from stent placement to surgery was 16 days (interquartile range 7–21). Technical and clinical success was achieved in all patients with a significant early improvement of symptoms. No adverse events due to the SEMS placement were observed. Conclusion. This pilot study confirmed the important role of nitinol conformable SEMS as a bridge to surgery option in the treatment of symptomatic malignant colorectal obstruction. PMID:24526914

  19. Endoscopic treatment of large pancreatic fluid collections (PFC) using self-expanding metallic stents (SEMS) – a two-center experience

    PubMed Central

    Chaves, Dalton Marques; Mönkemüller, Klaus; Carneiro, Fred; Medrado, Bruno; dos Santos, Marcos; Wodak, Stephanie; Reimão, Sílvia; Sakai, Paulo; de Moura, Eduardo

    2014-01-01

    Background/study aim: During the last several years, endoscopic ultrasound (EUS)-guided pancreatic fluid collections’ (PFC) drainage has evolved into the preferred drainage technique. Recently, self-expanding metallic stents (SEMS) have been used as an alternative to double pigtail stents, with the advantage of providing a larger diameter fistula, thereby decreasing the risk of early obstruction and also allowing for direct endoscopic exploration of the cavity. The aim of this study was to evaluate the technical and clinical success, safety, and outcome of patients undergoing EUS-guided drainage of complex PFC using SEMS. Patients/materials and methods: The study was conducted at two tertiary hospitals from January 2010 to January 2013. All patients with PFC referred for endoscopic drainage were enrolled in a prospective database. The inclusion criteria were: (1) patients with pseudocysts or walled-off necrosis based on the revised Atlanta classification; (2) symptomatic patients with thick PFC; (3) PFC that persisted more than 6 weeks; and (4) large PFC diameter (≥ 9 cm). The exclusion criteria consisted of coagulation disorders, PFC bleeding or infection, and failure-to-inform written consent. Results: A total of 16 patients (9 females, 7 males; mean age 52.6, range 20 – 82) underwent EUS drainage with SEMS. There were 14 cases of pseudocysts and 2 cases of walled-off necrosis. The etiologies of the PFC were mainly gallstones (8 of 16 patients, 50 %) and alcohol (5 of 16 patients, 31 %). Technical success was achieved in 100 % of the cases. All patients had a complete resolution of the PFC. Conclusion: Transmural EUS-guided drainage of complex PFC using SEMS is feasible, appears safe, and is efficacious. However, the exchange of the UC (uncovered)-SEMS for plastic stents is mandatory within 1 week. Future prospective studies, preferably multicenter studies, comparing SEMS versus traditional plastic stents for the drainage of PFC are

  20. Evaluation of the compressive mechanical properties of endoluminal metal stents.

    PubMed

    Schrader, S C; Beyar, R

    1998-06-01

    The mechanical properties of metal stents are important parameters in the consideration of stent design, matched to resist arterial recoil and vascular spasm. The purpose of this study was to develop a system for a standardized quantitative evaluation of the mechanical characteristics of various coronary stents. Several types of stents were compressed by external hydrostatic pressure. The stent diameter was assessed by placing a pair of small ultrasonic sono-crystals on the stent. From pressure-strain diagrams the ultimate strength and radial stiffness for each stent were determined. For all stents, except the MICRO-II and the Wiktor stent, the diameter decreased homogeneously until an ultimate compressive strength was exceeded, causing an abrupt collapse. Expanded to 3 mm, the mechanical behavior of the beStent, the Crown and the Palmaz-Schatz stent (PS153-series) were comparable. The spiral articulated Palmaz-Schatz stent showed twice the strength (1.26 atm) of the PS-153 (0.65 atm). The NIR stent yielded a maximum strength of 1.05 atm. The MICRO-II and the Wiktor stent did not collapse abruptly but rather showed a continuous decline of diameter with increasing external pressure. The Cardiocoil stent behaved in a fully elastic manner and showed the largest radial stiffness. Difference in mechanical properties between stents were documented using a new device specifically developed for that purpose. These mechanical stent parameters may have important clinical implications.

  1. Three cases of endoscopic resection for synchronous early colon cancers after self-expandable metallic stent placement for obstructive colon cancer

    PubMed Central

    Moroi, Rintaro; Endo, Katsuya; Ichikawa, Ryo; Takahashi, So; Shiroki, Takeharu; Shinkai, Hirohiko; Ishiyama, Fumitake; Kayaba, Shoichi

    2016-01-01

    Background and study aims: The feasibility of endoscopic resection for synchronous early colon cancer after placement of self-expandable metallic stents (SEMS) for malignant colorectal obstruction is unknown. Herein we evaluated 3 cases of endoscopic resection for synchronous early colorectal cancers after SEMS placement. Patient 1 was an 82-year-old man with obstructive sigmoid colon cancer. We curatively treated the synchronous descending colon cancer with endoscopic submucosal dissection (ESD) and the rectal cancer with endoscopic mucosal resection (EMR) after SEMS placement. This is the first reported case of a successful ESD for synchronous early colon cancer via the use of a colonic stent. Patient 2 was an 81-year-old man with obstructive ascending colon cancer. We resected the synchronous transverse colon cancer via ESD. Histologic findings indicated that the carcinoma cells had invaded the submucosal layer. Therefore, we immediately performed expanded right-hemicolectomy. Patient 3 was an 81-year-old man with obstructive sigmoid colon cancer. We curatively treated the synchronous transverse colon cancer with EMR after SEMS placement. There were no complications associated with the endoscopic treatments in any of the cases. Our results indicate that preoperative endoscopic resection combined with the ESD technique for synchronous colorectal cancer after SEMS placement could be effective as a surgical strategy for patients with malignant colorectal obstruction. PMID:27652303

  2. A Case of Aorto-Bronchial Fistula After Insertion of Left Main Bronchial Self-Expanding Metallic Stent in a Patient with Recurrent Esophageal Cancer

    SciTech Connect

    Onishi, Hiroshi Kuriyama, Kengo; Komiyama, Takafumi; Tanaka, Shiho; Marino, Kan; Tsukamoto, Tatsuaki; Araki, Tsutomu

    2004-09-15

    We report a case of aorto-bronchial fistula (ABF) caused by a self-expanding metallic stent (EMS) 51 days after insertion into the left main bronchus. The patient presented with left main bronchial stenosis caused by post-operative local recurrence of esophageal cancer. Post-operative radio therapy totaling 40 Gy and post-recurrence radiotherapy totaling 34 Gy were administered, with daily fractions of 2 Gy. Stenosis of the left main bronchus improved slightly, and was followed with insertion of EMS to prevent re-stenosis. The patient experienced massive hemoptysis for 3 days before sudden death. Autopsy revealed the EMS edge perforating the descending aortic lumen. Tumor infiltration and bacterial infection were observed on the wall of the left bronchus, and atherosclerosis was present on the aortic wall around the fistula. It should be noted that the left main bronchus was at considerable risk of ABF after insertion of EMS for malignant stenosis, and prophylactic stent insertion into the bronchus without imperative need must be avoided.

  3. Developments in metallic biodegradable stents.

    PubMed

    Hermawan, H; Dubé, D; Mantovani, D

    2010-05-01

    Interest in metallic degradable biomaterials research has been growing in the last decade. Both scientific journals and patent databases record a high increase in publications in this area. Biomedical implants with temporary function, such as coronary stents, are the targeted applications for this novel class of biomaterials. It is expected that stents made of degradable biomaterials, named biodegradable stents, will provide a temporary opening into a narrowed arterial vessel until the vessel remodels and will progressively disappear thereafter. Biodegradable stents made of metal have recently been progressed into preclinical tests in humans after their first introduction in early 2000s. By referring to patents and journal publications, this paper reviews the developments in biodegradable stents, with emphasis on those made of metals, starting from the first design ideas to validation testing.

  4. Use of a novel covered self-expandable metal stent with an anti-migration system for endoscopic ultrasound-guided drainage of a pseudocyst

    PubMed Central

    Téllez-Ávila, Félix Ignacio; Villalobos-Garita, Álvaro; Ramírez-Luna, Miguel Ángel

    2013-01-01

    The development of pseudocysts in patients with chronic pancreatitis has been reported in 23%-60% of cases and drainage is indicated when they become symptomatic. Endoscopic ultrasound-guided drainage with the placement of plastic or metallic stents to create a cystogastric anastomosis has been shown to be a reliable and efficacious maneuver. Metallic stent use appears to be a safe and effective alternative that shortens the length of time of the procedure and maintains a greater diameter in the cystogastric communication. However, important migration rates have been reported. The use of new metallic stents that are specially designed to prevent migration represents a promising development in the treatment of these group of patients that appears to be safe and effective for pseudocyst drainage and could importantly reduce migration rates, while at the same time having the advantage of a single step procedure and a larger fistula diameter in the endoscopic cystogastric anastomosis. PMID:23772268

  5. Nitinol Self-Expanding Stents for the Superficial Femoral Artery.

    PubMed

    Nathan, Ashwin; Kobayashi, Taisei; Giri, Jay

    2017-04-01

    The superficial femoral artery is a complex artery subject to a unique set of biomechanical loading conditions in its course through the leg. Plain balloon angioplasty and balloon-expandable stents had unacceptably high rates of restenosis, necessitating target vessel revascularization. Nitinol alloy is well suited to provide the strength and flexibility needed of stents to withstand the external forces posed by the environment of the superficial femoral artery. Advances in stent technology with the addition of a slow-releasing antiproliferative agent and changes in scaffold design have shown promise in reducing the rates of stent fracture and in-stent restenosis.

  6. Role of metallic stents in benign esophageal stricture

    NASA Astrophysics Data System (ADS)

    Shim, Chan Sup

    2012-10-01

    Simple esophageal strictures, which are focal, straight, and large in diameter, usually require 1 - 3 dilation sessions to relieve symptoms. However, complex strictures, which are long, tortuous, or associated with a severely compromised luminal diameter, are usually more difficult to treat with conventional bougie or balloon dilation techniques, and often have high recurrence rates. Although the permanent placement of self-expandable metal stents (SEMS) has been used to manage refractory benign esophageal strictures, this procedure is associated with additional problems, such as stricture from tissue hyperplasia, stent migration, and fistula formation. Thus, several new types of stents have been developed, including temporary SEMS, self-expandable plastic stents (SEPS), and biodegradable stents. The use of these new products has produced varied results. Temporary SEMS that have been used to relieve benign esophageal conditions have caused granulation tissue at both ends of the stent because of contact between the mucosa and the exposed metal components of the stent, thus hindering stent removal. We examined the tissue response to two new types of SEMS, a flange-type and a straighttype, each coated with a silicone membrane on the outside of the metal mesh. These two SEMS were evaluated individually and compared with a conventional control stent in animal experiments. Although the newly designed stents resulted in reduced tissue hyperplasia, and were thus more easily separated from the esophageal tissue, some degree of tissue hyperplasia did occur. We suggest that newly designed DES (drug-eluting stents) may provide an alternative tool to manage refractory benign esophageal stricture.

  7. [A case of severe motor and intellectual disability with tracheal stenosis due to granulation caused by metal stents treated successfully by silicone stents].

    PubMed

    Kotani, Haruko; Hino, Hiroyuki; Shiraishi, Taisuke; Ogura, Hideo

    2002-11-01

    A silicone stent (Dumon stent) was used in a severe motor and intellectual disability with severe tracheal stenosis due to granulation caused by an implanted the expanded metal stent (Ultraflex Nitinol Stent). To treat tracheobronchial malacia, diagnosed in infancy, expanded metalic stent was implanted at the ages of 30 and 32 years. However, a few months after the second implantation, progressive dyspnea appeared, and he had to use a respirator under intravenous anesthesia. Bronchoscopy showed re-stenosis of the trachea due to a granulation tissue within the stent. A Dumon stent was applied to control the re-stenosis. He was successfully weaned from a respirator. Since granulation tissue had recurred at the end of the Dumon stent after 3 months, a long term care of the airway and regular observation is necessary after implantation of stents.

  8. Balloon-expandable covered stent therapy of complex endovascular pathology.

    PubMed

    Giles, Heath; Lesar, Christopher; Erdoes, Luke; Sprouse, Richard; Myers, Stuart

    2008-11-01

    The current study was designed to investigate our hypotheses that balloon-expandable covered stents display acceptable function over longitudinal follow-up in patients with complex vascular pathology and provide a suitable alternative for the treatment of recurrent in-stent restenosis. All stents were Atrium iCast, which is a balloon-mounted, polytetrafluoroethylene-covered stent with a 6F/7F delivery system. A retrospective review was performed of 49 patients with 66 stented lesions. Data were analyzed with life tables and t-tests. The most commonly treated vessels were the iliac (61%) and renal (24%) arteries. Indications for covered stent placement were unstable atheromatous lesions (50%), recurrent in-stent restenosis (24%), aneurysm (8%), aortic bifurcation reconstruction (7.5%), dissection (4.5%), endovascular aneurysm repair-related (4.5%), and stent fracture (1.5%). Patency was assessed by angiogram or duplex ultrasonography. The primary end point was patency and secondary end points were technical success and access-site complications. Mean follow-up was 13 months (range 1.5-25). The technical success rate was 97%. Unsuccessful outcomes were due to deployment error (n=1) and stent malpositioning (n=1). The cohort (n=64) 6- and 12-month primary patency rates were 96% and 84%, respectively. Twelve-month assisted primary patency was 98%. Iliac artery stents (n=38) had a primary patency of 97% at 6 months and 84% at 12 months with an assisted primary patency of 100% at 12 months. Renal artery stents (n=16) had a primary patency of 92% at 6 months and 72% at 12 months with an assisted primary patency of 92% at 6 and 12 months. Stents placed for recurrent in-stent restenosis (n=16) had a primary patency of 85%, assisted primary patency of 93%, and a 15% restenosis rate at 12 months. Specifically, stents placed for renal artery recurrent in-stent restenosis (n=10) had a primary patency of 73%, assisted primary patency of 82%, and a restenosis rate of 27%. The

  9. Esophagojejunal Anastomosis Fistula, Distal Esophageal Stenosis, and Metalic Stent Migration after Total Gastrectomy

    PubMed Central

    Al Hajjar, Nadim; Popa, Calin; Al-Momani, Tareg; Margarit, Simona; Graur, Florin; Tantau, Marcel

    2015-01-01

    Esophagojejunal anastomosis fistula is the main complication after a total gastrectomy. To avoid a complex procedure on friable inflamed perianastomotic tissues, a coated self-expandable stent is mounted at the site of the anastomotic leak. A complication of stenting procedure is that it might lead to distal esophageal stenosis. However, another frequently encountered complication of stenting is stent migration, which is treated nonsurgically. When the migrated stent creates life threatening complications, surgical removal is indicated. We present a case of a 67-year-old male patient who was treated at our facility for a gastric adenocarcinoma which developed, postoperatively, an esophagojejunostomy fistula, a distal esophageal stenosis, and a metallic coated self-expandable stent migration. To our knowledge, this is the first reported case of an esophagojejunostomy fistula combined with a distal esophageal stenosis as well as with a metallic coated self-expandable stent migration. PMID:25945277

  10. Esophagojejunal anastomosis fistula, distal esophageal stenosis, and metalic stent migration after total gastrectomy.

    PubMed

    Al Hajjar, Nadim; Popa, Calin; Al-Momani, Tareg; Margarit, Simona; Graur, Florin; Tantau, Marcel

    2015-01-01

    Esophagojejunal anastomosis fistula is the main complication after a total gastrectomy. To avoid a complex procedure on friable inflamed perianastomotic tissues, a coated self-expandable stent is mounted at the site of the anastomotic leak. A complication of stenting procedure is that it might lead to distal esophageal stenosis. However, another frequently encountered complication of stenting is stent migration, which is treated nonsurgically. When the migrated stent creates life threatening complications, surgical removal is indicated. We present a case of a 67-year-old male patient who was treated at our facility for a gastric adenocarcinoma which developed, postoperatively, an esophagojejunostomy fistula, a distal esophageal stenosis, and a metallic coated self-expandable stent migration. To our knowledge, this is the first reported case of an esophagojejunostomy fistula combined with a distal esophageal stenosis as well as with a metallic coated self-expandable stent migration.

  11. In Vitro Comparison of Self-Expanding Versus Balloon-Expandable Stents in a Human Ex Vivo Model

    SciTech Connect

    Grenacher, Lars Rohde, Stefan Gaenger, Ellen; Deutsch, Jochen; Kauffmann, Guenter W.; Richter, Goetz M.

    2006-04-15

    The objective was to compare the radial strength and expansile precision of self-expanding stents and balloon-expandable stents in a human cadaver bifurcation model. Seven different self-expanding (LUMINEXX, JOSTENT SelfX, JOSTENT SelfX hrf, Sinus-Repo, Sinus SuperFlex, Easy Wallstent, SMART) and four different balloon-expandable stent models (Palmaz, Sinus Stent, SAXX Medium, JOSTENT peripheral), each type 10 stents (total n = 110 stents) were implanted into the common iliac arteries of human cadaver corpses. The maximum stent diameter was 10 mm for all models. After stent implantation, the specimens were filled with silicone caoutchouc. After 24 h, the vascular walls including the stents were removed from the hardened casts. Diameters were taken and the weight of the cast cylinders was measured in air and in purified water to calculate the volume of the bodies (according to Archimedes Law) as a relative but precise degree for the radial strength of the implanted stents. The cylindrical casts of the self-expanding stents showed lower mean diameters (8.2 {+-} 1.0 mm) and mean volumes (0.60 {+-} 0.14 ml/cm) than in the balloon-expandable stent group (10.1 {+-} 0.3 mm and 0.71 {+-} 0.04 ml/cm, respectively; p < 0.01). The nominal maximum diameter of 10 mm was not achieved in any of the self-expanding stents, but this was achieved in more than 70% (29/40) of the balloon-expandable stent specimens (p < 0.05). The variation between achieved volumes was significantly larger in self-expanding (range: 0.23-0.78 ml/cm) than in balloon-expandable stents (range: 0.66-0.81 ml/cm; p < 0.05). Self-expanding stents presented considerably lower radial expansion force and lower degree of precision than balloon-expandable stents.

  12. In vitro comparison of self-expanding versus balloon-expandable stents in a human ex vivo model.

    PubMed

    Grenacher, Lars; Rohde, Stefan; Gänger, Ellen; Deutsch, Jochen; Kauffmann, Günter W; Richter, Götz M

    2006-01-01

    The objective was to compare the radial strength and expansile precision of self-expanding stents and balloon-expandable stents in a human cadaver bifurcation model. Seven different self-expanding (LUMINEXX, JOSTENT SelfX, JOSTENT SelfX hrf, Sinus-Repo, Sinus SuperFlex, Easy Wallstent, SMART) and four different balloon-expandable stent models (Palmaz, Sinus Stent, SAXX Medium, JOSTENT peripheral), each type 10 stents (total n = 110 stents) were implanted into the common iliac arteries of human cadaver corpses. The maximum stent diameter was 10 mm for all models. After stent implantation, the specimens were filled with silicone caoutchouc. After 24 h, the vascular walls including the stents were removed from the hardened casts. Diameters were taken and the weight of the cast cylinders was measured in air and in purified water to calculate the volume of the bodies (according to Archimedes Law) as a relative but precise degree for the radial strength of the implanted stents. The cylindrical casts of the self-expanding stents showed lower mean diameters (8.2 +/- 1.0 mm) and mean volumes (0.60 +/- 0.14 ml/cm) than in the balloon-expandable stent group (10.1 +/- 0.3 mm and 0.71 +/- 0.04 ml/cm, respectively; p < 0.01). The nominal maximum diameter of 10 mm was not achieved in any of the self-expanding stents, but this was achieved in more than 70% (29/40) of the balloon-expandable stent specimens (p < 0.05). The variation between achieved volumes was significantly larger in self-expanding (range: 0.23-0.78 ml/cm) than in balloon-expandable stents (range: 0.66-0.81 ml/cm; p < 0.05). Self-expanding stents presented considerably lower radial expansion force and lower degree of precision than balloon-expandable stents.

  13. Treatment of Benign Tracheal Stenosis Utilizing Self-Expanding Nitinol Stents

    SciTech Connect

    Sesterhenn, Andreas M. Wagner, Hans-Joachim; Alfke, Heiko; Werner, Jochen A.; Lippert, Burkard M.

    2004-08-15

    We assessed the results of self-expanding metallic stent insertion into benign proximal tracheal stenosis in patients not appropriate or unfit for surgical repair. Proximal benign tracheal stenoses had occurred in 11 patients (7 men, 4 women, mean age 68.8 years) after long-time intubation (n = 6), tracheostomy (n = 4), or chondropathia (n = 1). Fourteen self-expanding nitinol stents were placed in the patients under general anesthesia with endoscopical and fluoroscopical guidance. Stent insertion was successful in all cases and led to immediate relief of the morphological and functional airway obstruction. No immediate complications were noted. During the mean follow-up period of 67.5 weeks we observed one recurrent dyspnea 3 months after implantation and granuloma formation at the stent insertion site in another patient. Both complications were successfully treated with additional stent insertion in one case and laser resection of granulomas in the other. Self-expanding nitinol stents should be considered for the treatment of benign proximal tracheal obstruction in selected patients for whom surgical repair is contraindicated.

  14. Expandable bioresorbable endovascular stent. I. Fabrication and properties.

    PubMed

    Su, Shih-Horng; Chao, Robert Y N; Landau, Charles L; Nelson, Kevin D; Timmons, Richard B; Meidell, Robert S; Eberhart, Robert C

    2003-06-01

    A bioresorbable, expandable poly(L-lactic acid) stent has been designed, based on a linear, continuous coil array principle, by which multiple furled lobes convert to a single lobe upon balloon expansion, without heating. Stent strength and compliance are sufficient to permit deployment by a conventional balloon angioplasty catheter. Several multiple lobe configurations were investigated, with expansion ratios ranging from 1.4 to 1.9 and expanded diameters ranging from 2.3 to 4.7 mm. Compression resistance of the expanded stent is dependent on fiber coil density and fiber ply. A range sufficient for endovascular service was obtained, with less than 4% elastic recoil in six day saline incubation studies. Surface plasma treatment with di(ethylene glycol) vinyl ether significantly reduced platelet adhesion in a 1 h porcine arteriovenous shunt model. Patency was maintained in one week implant studies in the porcine common femoral artery. However, a strong inflammatory response, and significant reduction of the vascular lumen were observed following two weeks implantation. The design principles and fabrication techniques for this bioresorbable stent are sufficiently versatile that a broad range of applications can be addressed. Much work remains to be done, including long-term evaluation of the inflammatory response, and of polymer degradation. The results of this study demonstrate the feasibility of expandable biodegradable stent design and deployment by conventional means.

  15. [Numerical modeling of shape memory alloy vascular stent's self-expandable progress and "optimized grid" of stent].

    PubMed

    Xu, Qiang; Liu, Yulan; Wang, Biao; He, Jin

    2008-10-01

    Vascular stent is an important medical appliance for angiocardiopathy. Its key deformation process is the expandable progress of stent in the vessel. The important deformation behaviour corresponds to two mechanics targets: deformation and stress. This paper is devoted to the research and development of vascular stent with proprietary intellectual property rights. The design of NiTinol self-expandable stent is optimized by means of finite element software. ANSYS is used to build the finite element simulation model of vascular stent; the molding material is NiTinol shape memory alloy. To cope with the factors that affect the structure of stent, the shape of grid and so on, the self-expanding process of Nitinol stent is simulated through computer. By making a comparison between two kinds of stents with similar grid structure, we present a new concept of "Optimized Grid" of stent.

  16. Stent Fracture and Reocclusion After Placement of a Single Self-Expanding Stent in the Common Iliac Artery and Endovascular Treatment

    SciTech Connect

    Higashiura, Wataru Sakaguchi, Shoji; Morimoto, Kengo; Kichikawa, Kimihiko

    2008-09-15

    We present a case of fracture of a single self-expanding stent placed in the common iliac artery (CIA). An 80-year-old woman underwent placement of a self-expanding stent for CIA occlusion. Stent fracture and reocclusion were detected after 18 months. Successful revascularization was achieved using a stent-in-stent maneuver. The possibility of stent fracture with reocclusion should be considered following treatment with a single self-expanding stent for CIA occlusion.

  17. Novel Use of a Uniquely Designed, Lumen-Apposing, Metal Stent in Benign Gastric Outlet Obstruction in Two Patients

    PubMed Central

    Pathirana, Induruwa; Magulick, John; Domanski, Jeremy; Okoh, Emuejevoke; Womeldorph, Craig

    2017-01-01

    Current guidelines recommend management of benign gastric outlet obstruction (GOO) with serial dilations. Self-expanding metal stents are effective, but their use is complicated by high rates of migration. We present two cases from our institution where a uniquely designed, lumen-apposing metal stent (LAMS) was successfully used to alleviate benign GOO without stent migration. PMID:28184377

  18. Structural Evaluation of Radially Expandable Cardiovascular Stents Encased in a Polyurethane Film

    NASA Technical Reports Server (NTRS)

    Trigwell, Steve; De, Samiran; Sharma, Rajesh; Mazumder, Malay K.; Mehta, Jawahar L.

    2004-01-01

    A method of encasing cardiovascular stents with an expandable polyurethane coating has been developed to provide a smooth homogeneous inner wall allowing for a confluent growth of endothelial cells. In this design, the metal wire stent structure is completely covered by the polyurethane film minimizing biocorrosion of the metal (stainless steel or nitinol), and providing a homogeneous surface for surface treatment and incorporation of various eluting drugs to prevent platelet aggregation while supporting endothelialization. The polyurethane surface was treated with a helium plasma for sterilization and promotes growth of cells. The paper details the performance of the coated film to expand with the metal stent up to 225 % during deployment. We present stress/strain behavior of polyurethane films, and subsequent plasma treatment of the surface and the adhesion of the coating to the stent structure upon expansion. A film of less than 25 tm was found to be sufficient for corrosion resistance and flexibility without producing any excess stress on the stent structure. Straining the film to 225 % and plasma modification did not affect the mechanical and surface properties while allowing for improved biocompatibility as determined by the critical surface tension, surface chemistry, and roughness.

  19. Structural evaluation of radially expandable cardiovascular stents encased in a polyurethane film.

    PubMed

    Trigwell, Steve; De, Samiran; Sharma, Rajesh; Mazumder, Malay K; Mehta, Jawahar L

    2006-02-01

    A method of encasing cardiovascular stents with an expandable polyurethane coating has been developed to provide a smooth homogeneous inner wall allowing for a confluent growth of endothelial cells. In this design, the metal wire stent structure is completely covered by the polyurethane film, minimizing biocorrosion of the metal (stainless steel or nitinol), and providing a homogeneous surface for surface treatment and incorporation of various eluting drugs to prevent platelet aggregation while supporting endothelialization. The polyurethane surface was treated with a helium plasma for sterilization and promotes growth of cells. The article details the performance of the coated film to expand with the metal stent up to 225% during deployment. Stress/strain behavior of polyurethane films, subsequent plasma treatment of the surface, and the adhesion of the coating to the stent structure upon expansion are presented. A film of less than 25 microm was found to be sufficient for corrosion resistance and flexibility without producing any excess stress on the stent structure. Straining the film to 225% and plasma modification did not affect the mechanical and surface properties, but allowed for improved biocompatibility as determined by the critical surface tension, surface chemistry, and roughness.

  20. Clinical application of metallic stents in treatment of esophageal carcinoma

    PubMed Central

    Yang, Hai-Shan; Zhang, Lin-Bo; Wang, Tian-Wei; Zhao, Yong-Sheng; Liu, Lin

    2005-01-01

    AIM: To evaluate the effects of self-expanding metal stents (SEMS) in patients with malignant esophageal obstruction and to analyze their prognosis and complications. METHODS: Seventy-four metallic stents were placed under fluoroscopic guidance in 66 patients with esophageal obstruction secondary to carcinoma, of whom, 6 cases were complicated by fistula. RESULTS: After seventy-two stents were successfully used in 66 cases without any severe complications (technical successful rate was 97%), the dysphagia score improved from 3.3±0.6 to 0.8±0.5 (P<0.01), and life quality improved significantly in all these patients. All fistulae were sealed immediately after coated stents were inserted in the six patients. New stents were placed in two patients: the stent migrated more than 2 cm, in one patient and the stent slipped into stomach in the other. Minor bleeding was found only in 28 patients during the operation. Reobstruction was found in 12 patients, but was successfully cured under endoscopy. The survival rate was 78%, 57% and 11% for 6 mo, 1 year and 2 years respectively. CONCLUSION: Placement of SEMS is a simple, safe, quick and efficient surgical method for treating esophageal carcinoma obstruction. It may be used mainly as a palliative treatment of esophageal obstruction secondary to carcinoma. PMID:15637767

  1. Finite element modeling of a progressively expanding shape memory stent.

    PubMed

    Thériault, Philippe; Terriault, Patrick; Brailovski, Vladimir; Gallo, Richard

    2006-01-01

    Cardiovascular stents are small cylindrical devices introduced in stenosed arteries to reopen the lumen and restore blood flow. However, this treatment presents complications, including restenosis, which is the reclosing of the artery's diameter after the insertion of a stent. The structure of the prosthesis penetrates into and injures the walls of the patient's artery. There then follows a proliferation of cells and the formation of scar tissue around the injury, similar to the scarring of other organic tissues. This reaction to the trauma subjects the artery to close. The proposed solution is to develop a Nitinol stent with a progressive expansion device made of polyethylene, allowing smooth and gradual contact between the stent and the artery's wall by creep effect. The purpose of this paper is to describe the technology and methodology for the numerical study of this kind of stent through the finite element method. ANSYS 8.0 software is used to perform the analysis. The Nitinol is modeled with a superelastic law and the polyethylene with a yield hardening law. A first simulation determines the final geometry of the stent laser cut from a small tube. A second simulation examines the behavior of the prosthesis during surgery and over the 4 weeks following the operation. The results demonstrate that a compromise can be reached between a limited expansion prior the inflation of the expandable balloon and a significant expansion by creep of the polymer rings.

  2. Palliative Treatment of Malignant Colorectal Strictures with Metallic Stents

    SciTech Connect

    Paul Diaz, Laura; Pinto Pabon, Isabel; Fernandez Lobato, Rosa; Montes Lopez, Carmen

    1999-01-15

    Purpose: To assess the effectiveness and safety of self-expanding metallic stents as a primary palliative treatment for inoperable malignant colorectal strictures. Methods: Under radiological guidance 20 self-expanding metallic Wallstents were implanted in 16 consecutive patients with colorectal stenoses caused by malignant neoplasms, when surgical treatment of the condition had been ruled out. The patients were followed up clinically for 1-44 months, until death or termination of this study. Results: The stents were successfully implanted in all cases and resolved the clinical obstruction in all the patients except one, who underwent subsequent colostomy. During follow-up of the remaining 15 patients, clinical complications arising from the procedure were pain (two patients), minor rectal bleeding (one patient), and severe rectal bleeding (one patient) (26%). There were three cases of stent migration and three cases of stent occlusion, and reintervention by us was necessary in 20% of cases (3/15). The mean life span following the procedure was 130 days, and none of the patients exhibited clinical symptoms of obstruction at the time of death (12 patients) or termination of the study (3 patients). Conclusion: Deployment of metallic stents under radiologic guidance is an effective alternative as a primary palliative measure in malignant colorectal obstruction, though the possible clinical complications and need for repeat intervention during follow-up should be taken into account.

  3. Miniaturized Self-Expanding Drug-Eluting Stent in Small Coronary Arteries: Late Effectiveness

    PubMed Central

    de Oliveira, Flavio Roberto Azevedo; Mattos, Luiz Alberto Piva e; Abizaid, Alexandre; Abizaid, Andrea S.; Costa, J. Ribamar; Costa, Ricardo; Staico, Rodolfo; Botelho, Roberto; Sousa, J. Eduardo; Sousa, Amanda

    2013-01-01

    Background Small vessels represent a risk factor for restenosis in percutaneous coronary angioplasty (PCA). The Sparrow® self-expanding drug-eluting stent, which has a lower profile than the current systems, has never been tested in this scenario. Objectives To evaluate the late effectiveness of the Sparrow® drug-eluting stent, regarding in-stent late lumen loss (LLL). Methods Patients with ischemia, symptomatic or documented, were submitted to PCA in vessels with reference diameter < 2.75 mm, divided into two groups regarding Sparrow® stent type: group 1: Sparrow® drug-eluting stent (DES), group 2: Sparrow® bare metal stent (BMS). Clinical follow-up duration was 12 months. Evaluation using quantitative coronary angiography (QCA) was performed immediately and at 8 months. A decrease of over 65% of in-stent LLL with DES was estimated to calculate sample size. IBM® SPSS software, release 19 (Chicago, Illinois, USA) was used for the statistical analysis. Results A total of 24 patients were randomized, 12 in each group. The DES and BMS groups were similar in age (63.25 ± 10.01 vs. 64.58 ± 11.54, p = 0.765), male gender (58.3% vs. 33.3%, p = 0.412), risk factors and all angiographs aspects. Immediate results were satisfactory in both groups. At 8 months in-stent late lumen loss was significantly lower in DES than in BMS group (DES vs. BMS 0.25 ± 0.16 0.97 ± 0.76, p = 0.008). Conclusion In small-vessel PCA, the Sparrow® DES determined significant reduction in in-stent LLL, when compared to Sparrow® BMS. PMID:24100691

  4. Clinical experience with ureteral metal stents

    PubMed Central

    Al Aown, Abdulrahman; Iason, Kyriazis; Panagiotis, Kallidonis; Liatsikos, Evangelos N.

    2010-01-01

    Ureteral metal stents (MSs) present a minimally invasive tool to preserve the drainage of renal pelvis whenever ureteral patency is at risk to be obstructed due to extrinsic or intrinsic etiologies. Clinical experience with these stents demonstrates that they impose a promising alternative treatment option in ureteral pathologies that are difficult to be treated via common polymeric stents. Current application of MSs in the treatment of both benign and malignant ureteral obstruction reveals quite promising results. Nevertheless, the ideal MS that would provide uncomplicated long-term effectiveness is still lucking and current MS usage is facing several adverse effects between which stent obstruction, encrustation, infection, migration, and patient discomfort. Ongoing attempts to create more inert stent with sophisticated novel designs are expected to improve current MS efficiency. MSs will play a major role in the future as a routine management of a variety of ureteral pathologies. PMID:21369375

  5. Differences in Endothelial Injury After Balloon Angioplasty, Insertion of Balloon-Expanded Stents or Release of Self-Expanding Stents: An Electron Microscopic Experimental Study

    SciTech Connect

    Harnek, Jan; Zoucas, Evita; Carlemalm, Erik; Cwikiel, Wojciech

    1999-01-15

    Purpose: To evaluate which of six different commonly available stents inserted into an artery without percutaneous transluminal angioplasty (PTA) causes the least endothelial damage. To compare the degree of endothelial injury after insertion of such a stent with injury caused by PTA. Methods: Twelve healthy pigs were used in the experiments. In the first part of the study six different types of stents were inserted into the common iliac arteries. In the second part of the study self-expanding stents with large spaces between the wires were used. PTA was performed in the contralateral iliac artery. The pigs were killed immediately after the procedure and resected specimens examined after fixation, using scanning electron microscopy. Results: All procedures but two were accomplished successfully. More endothelium was preserved after insertion of self-expanding stents with large spaces between the wires, compared with stents with small spaces and balloon-expanded stents. After insertion of self-expanding stents with large spaces, 50.1% {+-} 16.4% of the endothelium remained intact, compared with only 5.6% {+-} 7.7% after PTA. The difference was statistically significant (p < 0.001). Conclusion: Self-expanding stents with large spaces between the wires, inserted without PTA, cause less damage to the endothelium than other stents and significantly less damage than PTA.

  6. Comparison of Drug-eluting Coronary Stents, Bare Coronary Stents and Self-expanding Stents in Angioplasty of Middle Cerebral Artery Stenoses

    PubMed Central

    Lee, Jong-Hyeog; Jo, Sung-Min; Jo, Kwang-Deog; Kim, Moon-Kyu; Lee, Sang-Youl

    2013-01-01

    Objective The purpose of this study is to investigate the results of treatment using stent-angioplasty for symptomatic middle cerebral arterial (MCA) stenosis and comparison of in-stent restenosis between drug-eluting stents (DES), bare metal coronary stents (BMS) and self-expanding stents (SES). Materials and Methods From Jan. 2007 to June. 2012, 34 patients (mean age ± standard deviation: 62.9 ± 13.6 years) with MCA stenosis were treated. Inclusion criteria were acute infarction or transient ischemic attacks (TIAs) and angiographically proven symptom related severe stenosis. Stents used for treatment were DES (n = 8), BMS (n = 13) and SES (n = 13). National Institutes of Health Stroke Scale (NIHSS) at admission was 2.5 ± 3.1 and mean stenosis rate was 79.0 ± 8.2%. Assessment of clinical and angiographic results was performed retrospectively. Results Among 34 patients, periprocedural complications occurred in four cases (11.8%), however, only two cases (6.0%) were symptomatic. All patients were followed clinically (mean follow-up period; 40.7 ± 17.7 months) and 31 were followed angiographically (91.2%. 13.4 ± 8.5 months). There was no occurrence of repeat stroke in all patients; however, mild TIAs related to restenosis occurred in three of 34 patients (8.8%). The mean NIHSS after stent-angioplasty was 1.7 ± 2.9 and 0.8 ± 1.1 at discharge. The modified Rankin score (mRS) at discharge was 0.5 ± 0.9 and 0.3 ± 0.8 at the last clinical follow-up. In-stent restenosis over 50% occurred in five of 31 angiographically followed cases (16.1%), however, all of these events occurred only in patients who were treated with BMS or SES. Restenosis rate was 0.0% in the DES group and 20.8% in the other group (p = 0.562); it did not differ between BMS and SES (2/11 18.2%, 3/13 23.1%, p = 1.000). Conclusion Stent-angioplasty appears to be effective for symptomatic MCA stenosis. As for restenosis, in our study, DES was presumed to be more effective than BMS and SES; meanwhile

  7. Expanding hollow metal rings

    DOEpatents

    Peacock, Harold B.; Imrich, Kenneth J.

    2009-03-17

    A sealing device that may expand more planar dimensions due to internal thermal expansion of a filler material. The sealing material is of a composition such that when desired environment temperatures and internal actuating pressures are reached, the sealing materials undergoes a permanent deformation. For metallic compounds, this permanent deformation occurs when the material enters the plastic deformation phase. Polymers, and other materials, may be using a sealing mechanism depending on the temperatures and corrosivity of the use. Internal pressures are generated by either rapid thermal expansion or material phase change and may include either liquid or solid to gas phase change, or in the gaseous state with significant pressure generation in accordance with the gas laws. Sealing material thickness and material composition may be used to selectively control geometric expansion of the seal such that expansion is limited to a specific facing and or geometric plane.

  8. Acute Duodenal Obstruction After Percutaneous Placement of Metallic Biliary Stents: Peroral Treatment with Enteral Stents

    SciTech Connect

    Lopera, Jorge E. Alvarez, Oscar A.; Perdigao, Joseph; Castaneda-Zuniga, Wilfrido

    2003-09-15

    Three patients with malignant biliary obstruction were treated with placement of metallic biliary stents. Two patients had known partial duodenal stenosis but had no symptoms of gastrointestinal obstruction. The patients developed symptomatic duodenal obstruction early after biliary metallic stent placement. The symptomatic duodenal obstructions were successfully treated with peroral placement of duodenal stents, which obviated the need for surgical intervention.

  9. Hepatocellular Carcinoma Complicated by Gastroduodenal Obstruction: Palliative Treatment with Metallic Stent Placement

    SciTech Connect

    Lee, Ye Jin; Kim, Jin Hyoung Song, Ho-Young; Park, Jung-Hoon; Na, Han Kyu; Kim, Pyeong Hwa; Fan, Yong

    2012-10-15

    Purpose: To evaluate the clinical effectiveness of self-expandable metallic stents in seven patients with malignant gastroduodenal obstruction caused by inoperable hepatocellular carcinoma (HCC). Methods: Seven patients with gastroduodenal obstruction caused by advanced HCC underwent metallic stent placement from 2003 to 2010. These patients had total dysphagia (n = 5) or were able to eat only liquids (n = 2) before stent placement. Patients had Eastern Cooperative Oncology Group performance scores of 2 or 3, and Child-Pugh classification B or C. Results: Stent placement was technically successful in all seven patients (100%) and clinically successful in six (86%). Five patients could eat a soft diet, and one patient tolerated regular diet after stent placement. Stent-related obstructive jaundice occurred in one patient. One patient had hematemesis 11 days after stent placement. Overall mean survival was 51 days (range, 10-119 days). Stent patency was preserved in six patients with clinical success until death. Conclusion: Placement of a covered self-expandable metallic stent may offer good palliation in patients with gastroduodenal obstruction due to advanced HCC.

  10. Self-Expandable Nitinol Stent Placement in Homocysteinemic Porcine Aorta

    PubMed Central

    França, Luís Henrique Gil; Pereira, Adamastor Humberto; Perini, Sílvio César

    2008-01-01

    PURPOSE To compare aortic intimal thickening of normal and hyperhomocysteinemic pigs (induced with a methionine-rich diet) following placement of a self-expanding nitinol stent. METHODS Eighteen Macau pigs were used. They were older than eight weeks in age and had an average weight of 30 kg. Pigs were randomly divided into two groups. The first, Group C (control), was fed a regular diet, and the second group, Group M, was fed a methionine-rich diet for 30 days to induce hyperhomocysteinemia. The self-expandable nitinol stents were 25mm in length and 8 mm in diameter after expansion. Blood samples were collected to measure total cholesterol, triglycerides, HDL and homocysteine concentrations. All animals were subjected to angiography. Thirty days after the procedure, the animals were sacrificed, and the abdominal aorta was removed for histological and digital morphometry analysis. RESULTS Under microscopic evaluation, the intima was significantly thicker in Group C than in Group M. When groups were compared by digital morphometric analysis, intimal thickening of the vessel wall was higher in Group C than in Group M. There was no significant change in total cholesterol, triglycerides or HDL concentrations in either group. In group C the levels of plasma homocysteine ranged from 14,40 to 16,73μmol/l; in Group M, plasma homocysteine levels ranged from 17.47 to 59.80 μmol/l after 30 days of a methionine-rich diet. CONCLUSION Compared to normal pigs, less intimal hyperplasia was observed in the abdominal aortas of hyperhomocysteinemic pigs thirty days after the insertion of a self-expandable nitinol stent. PMID:18438578

  11. Metallic Stents for Tracheobronchial Pathology Treatment

    SciTech Connect

    Serrano, Carolina; Laborda, Alicia; Lozano, Juan M.; Caballero, Hugo; Sebastian, Antonio; Lopera, Jorge; Gregorio, Miguel Angel de

    2013-12-15

    Purpose: To present the 7-year experience of the treatment of benign and malignant tracheobronchial stenoses using metallic stents. Patients and Methods: One hundred twenty-three stents were inserted in 86 patients (74 benign and 12 malignant stenoses). Ninety-seven stents were placed in the trachea and 26 in the bronchi. The procedures were performed under fluoroscopic and flexible bronchoscopic guidance with the patient under light sedation. In cases of severe stenotic lesions or obstructions, laser resection was performed before stent placement. Clinical and functional pulmonary data were recorded before and 3 months after the procedure. Follow-up involved clinical data and radiographic techniques at 48 h and at 1-, 3-, 6-, and 12-month intervals. Results: The technical success was 100 %. Dyspnea disappearance, forced expiratory volume in the first second, and pulmonary functional data improvement was observed in all patients (p < 0.001). Complications were detected in 23 patients (26.7 %). Mean follow-up time was 6.3 {+-} 1.2 months in patients with malignant lesions and 76.2 {+-} 2.3 months patients with in benign lesions. By the end of the study, 100 % of patients with malignant pathology and 6.7 % of patients with benign lesions had died. Conclusion: Endoluminal treatment of tracheobronchial stenosis with metallic stents is a therapeutic alternative in patients who are poor candidates for surgery. In unresectable malignant lesions, the benefit of metallic stenting is unquestionable. In benign lesions, the results are satisfactory, but sometimes other interventions are required to treat complications. New stent technology may improve these results.

  12. Temporary endoscopic metallic stent for idiopathic esophageal achalasia.

    PubMed

    Coppola, Franco; Gaia, Silvia; Rolle, Emanuela; Recchia, Serafino

    2014-02-01

    Idiopathic achalasia is a motor disorder of the esophagus of unknown etiology caused by loss of motor neurons determining an altered motility. It may determine severe symptoms such as progressive dysphagia, regurgitations, and pulmonary aspirations. Many therapeutic options may be offered to patients with achalasia, from surgery to endoscopic treatments such as pneumatic dilation, botulinum injection, peroral endoscopic myotomy, or endoscopic stenting. Recently, temporary placement of a stent was proposed by Cheng as therapy for achalasia disorders, whereas no Western authors have dealt with it up to date. The present study reports our preliminary experience in 7 patients with achalasia treated with a temporary stent. Partially covered self-expanding metallic stents (Micro-Tech, Nanjin, China) 80 mm long and 30 mm wide were placed under fluoroscopic control and removed after 6 days. Clinical follow-up was scheduled to check endoscopic success, symptoms release, and complications. The placement and the removal of the stents were obtained in all patients without complications. Mean clinical follow-up was 19 months. Five out of 7 patients referred total symptoms release and 2 experienced significant improvement of dysphagia. The procedure was not time consuming and was safe; no mild or severe complications were registered. In conclusion, our results may suggest a possible safe and effective endoscopic alternative treatment in patients with achalasia; however, further larger studies are necessary to confirm these promising, but very preliminary, data.

  13. Percutaneous Placement of Permanent Metallic Stents in the Cystic Duct to Treat Obstructive Cholecystitis.

    PubMed

    Brown, Nicholas I; Jhamb, Ashu; Brooks, Duncan M; Little, Andrew F

    2015-12-01

    This report presents a series of five patients unsuitable for surgery who had nonretrievable self-expanding metallic stents deployed along the cystic duct as treatment for benign and malignant causes of gallbladder obstruction. Techniques are described for draining cholecystitis, removing gallstones, bypassing gallbladder obstructions, and inserting metallic stents across the cystic duct to restore permanent antegrade gallbladder drainage in acute and chronic cholecystitis. Symptoms resolved in all cases, and stents remained patent for as long as 22 months. This procedure may be an effective alternative to cholecystectomy or long-term gallbladder drainage for patients in inoperable condition.

  14. Insertion of Self-Expandable Nitinol Stents Without Previous Balloon Angioplasty Reduces Restenosis Compared with PTA Prior to Stenting

    SciTech Connect

    Harnek, Jan; Zoucas, Evita; Stenram, Unne; Cwikiel, Wojciech

    2002-10-15

    Purpose: To compare the development of intimal hyperplasia after deployment of a self-expanding nitinol stent with and without previous percutaneous transluminal balloon angioplasty (PTA), with the results after PTA alone. Methods: In nine healthy pigs, the iliac arteries were divided into three groups: group 1 (n = 6 arteries) was treated with PTA; group 2 n 6)with insertion of self-expanding stents after PTA; and group 3 (n = 6) with stent insertion without previous PTA. After 8 weeks the vessels were examined with intravascular ultrasonography,histologic examination and morphometric analysis. Results: Although the injury index in group 1 (0.17{+-} 0.57) was lower (p <0.05) than in group 2 (0.26 {+-} 0.06) and group 3 (0.26 {+-} 0.08), PTA-treated arteries showed significantly (p <0.05) reduced mean luminal gain (0.53 {+-} 2.84) compared with arteries treated with PTA prior to stenting (2.58 {+-} 1.38) and compared with stenting alone (4.65 {+-}5.34). Stenting after PTA resulted in a higher (p<0.05) restenosis index (2.63 {+-} 1.06) compared with stenting without PTA (1.35 {+-} 0.59). Group 2 also had a significantly thicker intimap <0.05) and 83% and 74% higher intima/mediaratio (p <0.05) compared with groups 1 and 3, respectively. Conclusion: Insertion of a self-expandable nitinol stent without previous PTA results in less intimalhyperplasia than if PTA is performed prior to stenting, suggesting that direct stenting can be used in angioplasty sessions with a favorable outcome.

  15. Sequential Structural and Fluid Dynamics Analysis of Balloon-Expandable Coronary Stents: A Multivariable Statistical Analysis.

    PubMed

    Martin, David; Boyle, Fergal

    2015-09-01

    Several clinical studies have identified a strong correlation between neointimal hyperplasia following coronary stent deployment and both stent-induced arterial injury and altered vessel hemodynamics. As such, the sequential structural and fluid dynamics analysis of balloon-expandable stent deployment should provide a comprehensive indication of stent performance. Despite this observation, very few numerical studies of balloon-expandable coronary stents have considered both the mechanical and hemodynamic impact of stent deployment. Furthermore, in the few studies that have considered both phenomena, only a small number of stents have been considered. In this study, a sequential structural and fluid dynamics analysis methodology was employed to compare both the mechanical and hemodynamic impact of six balloon-expandable coronary stents. To investigate the relationship between stent design and performance, several common stent design properties were then identified and the dependence between these properties and both the mechanical and hemodynamic variables of interest was evaluated using statistical measures of correlation. Following the completion of the numerical analyses, stent strut thickness was identified as the only common design property that demonstrated a strong dependence with either the mean equivalent stress predicted in the artery wall or the mean relative residence time predicted on the luminal surface of the artery. These results corroborate the findings of the large-scale ISAR-STEREO clinical studies and highlight the crucial role of strut thickness in coronary stent design. The sequential structural and fluid dynamics analysis methodology and the multivariable statistical treatment of the results described in this study should prove useful in the design of future balloon-expandable coronary stents.

  16. Oversizing and Restenosis with Self-Expanding Stents in Iliofemoral Arteries

    SciTech Connect

    Saguner, Ardan M. Traupe, Tobias; Raeber, Lorenz; Hess, Nina; Banz, Yara; Saguner, Arhan R.; Diehm, Nicolas; Hess, Otto M.

    2012-08-15

    Purpose: Uncoated self-expanding nitinol stents (NS) are commonly oversized in peripheral arteries. In current practice, 1-mm oversizing is recommended. Yet, oversizing of NS may be associated with increased restenosis. To provide further evidence, NS were implanted in porcine iliofemoral arteries with a stent-to-artery-ratio between 1.0 and 2.3. Besides conventional uncoated NS, a novel self-expanding NS with an antiproliferative titanium-nitride-oxide (TiNOX) coating was tested for safety and efficacy. Methods: Ten uncoated NS and six TiNOX-coated NS (5-6 mm) were implanted randomly in the iliofemoral artery of six mini-pigs. After implantation, quantitative angiography (QA) was performed for calculation of artery and minimal luminal diameter. Follow-up was performed by QA and histomorphometry after 5 months. Results: Stent migration, stent fracture, or thrombus formation were not observed. All stents were patent at follow-up. Based on the location of the stent (iliac/femoral) and the stent-to-artery-ratio, stent segments were divided into 'normal-sized' (stent-to-artery-ratio < 1.4, n = 12) and 'oversized' (stent-to-artery-ratio {>=} 1.4, n = 9). All stent segments expanded to their near nominal diameter during follow-up. Normal-sized stent segments increased their diameter by 6% and oversized segments by 29%. A significant correlation between oversizing and restenosis by both angiography and histomorphometry was observed. Restenosis rates were similar for uncoated NS and TiNOX-coated NS. Conclusions: TiNOX-coated NS are as safe and effective as uncoated NS in the porcine iliofemoral artery. All stents further expand to near their nominal diameter during follow-up. Oversizing is linearly and positively correlated with neointimal proliferation and restenosis, which may not be reduced by TiNOX-coating.

  17. Use of nitinol self-expandable stents in 26 dogs with tracheal collapse.

    PubMed

    Beranek, J; Jaresova, H; Rytz, U

    2014-02-01

    A study was designed to describe a novel approach to the treatment of tracheal collapse (TC) in dogs using self-expandable nitinol stents. Medical records were reviewed retrospectively for 26 client owned dogs in which nitinol stents were deployed. The entire length of trachea was supported independently of the extent of TC. Two overlapping stents were used instead of one in cases where one stent was not spanning the entire trachea adequately. The diameter of the cranial radiolucent portion of trachea, just behind the cricoid cartilage, was measured as a specific landmark to select the appropriate size of the stent. Two self-expandable nitinol stents were inserted in 9 of 26 dogs; the trachea in the rest of the cases was supported with only one stent. A follow up tracheoscopy was performed in 10 of 26 cases with recurrent clinical signs. Secondary tracheal stenosis in these cases was caused by stent fracture, granuloma or excessive stent shortening. Additional stents were placed successfully to expand the stenotic lumen. A support of the entire trachea may decrease risk of nitinol fracture at the end of the implant. Long term clinical improvement (25 of 26 dogs, 96 %) is comparable with the results of other studies.

  18. Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters

    SciTech Connect

    Chung, Hwan-Hoon Lee, Seung Hwa; Cho, Sung Bum; Park, Hong Suk; Kim, Young Sik; Kang, Byung Chul; Frisoli, Joan K.; Razavi, Mahmood K.

    2008-05-15

    The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30-40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted.

  19. Self-expanding stents and aortoiliac occlusive disease: a review of the literature

    PubMed Central

    Bekken, Joost A; Jongsma, Hidde; de Vries, Jean-Paul PM; Fioole, Bram

    2014-01-01

    The treatment of symptomatic aortoiliac occlusive disease has shifted from open to endovascular repair. Both short- and long-term outcomes after percutaneous angioplasty and stenting rival those after open repair and justify an endovascular-first approach. In this article, we review the current endovascular treatment strategies in patients with aortoiliac occlusive disease, indications for primary and selective stenting in the iliac artery, and physical properties and future perspectives of self-expanding stents. PMID:24833925

  20. Implantation study of a tissue-engineered self-expanding aortic stent graft (bio stent graft) in a beagle model.

    PubMed

    Kawajiri, Hidetake; Mizuno, Takeshi; Moriwaki, Takeshi; Iwai, Ryosuke; Ishibashi-Ueda, Hatsue; Yamanami, Masashi; Kanda, Keiichi; Yaku, Hitoshi; Nakayama, Yasuhide

    2015-03-01

    The use of stent grafts for endovascular aortic repair has become an important treatment option for aortic aneurysms requiring surgery. This treatment has achieved excellent outcomes; however, problems like type 1 endoleaks and stent graft migration remain. Bio stent grafts (BSGs), which are self-expanding stents covered with connective tissue, were previously developed using "in-body tissue architecture" technology. We assessed their early adaptation to the aorta after transcatheter implantation in a beagle model. BSGs were prepared by subcutaneous embedding of acryl rods mounted with self-expanding nitinol stents in three beagles for 4 weeks (n = 3/dog). The BSGs were implanted as allografts into infrarenal abdominal aortas via the femoral artery of three other beagles. After 1 month of implantation, aortography revealed no stenosis or aneurysmal changes. The luminal surface of the BSGs was completely covered with neointimal tissue, including endothelialization, without any thrombus formation. The cover tissue could fuse the luminal surface of the native aorta with tight conjunctions even at both ends of the stents, resulting in complete impregnation of the strut into the reconstructed vascular wall, which is expected to prevent endoleaks and migration in clinical applications.

  1. Treatment of Pelvic Venous Spur (May-Thurner Syndrome) with Self-Expanding Metallic Endoprostheses

    SciTech Connect

    Binkert, Christoph A.; Schoch, Eric; Stuckmann, Gerd; Largiader, Jon; Wigger, Pius; Schoepke, Wolfdietrich; Zollikofer, Christoph L.

    1998-01-15

    Purpose: The application of self-expanding metallic endoprostheses (stents) to treat symptomatic pelvic venous spurs as an alternative to surgery. Methods: Wallstents with a diameter from 14 to 16 mm and one Cragg stent were placed in the left common iliac vein of eight patients (seven women, one man; mean age 42 years) with a symptomatic pelvic venous spur (left deep venous thrombosis or post-thrombotic leg swelling). Four patients had surgical thrombectomy prior to stent placement. Results: Technical success with immediate reduction of left leg circumference was achieved in all eight patients. A primary patency rate of 100% was observed during an average follow-up of 3 years (range 10-121 months). There were no procedural or stent-related complications. Conclusion: The percutaneous transfemoral placement of self-expanding metallic stents is an effective minimally invasive alternative to surgery in the treatment of symptomatic pelvic venous spur.

  2. Radial forces of stents used in thoracic endovascular aortic repair and bare self-expanding nitinol stents measured ex vivo - Rapid rescue for obstruction of the innominate artery using bare self-expanding nitinol stents.

    PubMed

    Matsumoto, Takuya; Inoue, Kentaro; Tanaka, Shinichi; Aoyagi, Yukihiko; Matsubara, Yutaka; Matsuda, Daisuke; Yoshiya, Keiji; Yoshiga, Ryosuke; Ohkusa, Tomoko; Maehara, Yoshihiko

    2017-02-01

    Purpose Our objective was to compare the radial forces of several stents ex vivo to identify stents suitable for rescue of the unexpected coverage of aortic arch branches in thoracic endovascular aortic repair. Methods We measured the radial forces of two types of self-expanding bare nitinol stents (E-luminexx and Epic) used singly or as double-walled pairs, and of three endoprostheses used in thoracic endovascular aortic repair (TEVAR, Gore c-TAG, Relay, and Valiant) by compressing the stent using an MTS Instron universal testing machine (model #5582). We also examined the compressive effects of the TEVAR endoprostheses and the bare nitinol stents on each other. Results The radial force was greater in the center than at the edge of each stent. In all stents tested, the radial force decreased incrementally with increasing stent diameter. The radial force at the center was two times greater when using two stents than with a single stent. In the compression test, only E-luminexx used as a pair was not compressed after compressing a Relay endoprosthesis by 12 mm. Conclusion Two E-luminexx stents are appropriate to restore the blood flow if a TEVAR endoprosthesis covers the innominate artery following innominate-carotid-left subclavian arterial bypass.

  3. The development of self-expanding peripheral stent with ion-modified surface layer

    NASA Astrophysics Data System (ADS)

    Lotkov, Alexander I.; Kashin, Oleg A.; Kudryashov, Andrey N.; Krukovskii, Konstantin V.; Kuznetsov, Vladimir M.; Borisov, Dmitry P.; Kretov, Evgenii I.

    2016-11-01

    In work researches of chemical composition of surface layers of self-expanding stents of nickel-titanium (NiTi) and their functional and mechanical properties after plasma immersion processing by ions of silicon (Si). It is established that in the treatment in the inner and outer surfaces of stents formed doped silicon layer with a thickness of 80 nm. The formation of the doped layer does not impair the functional properties of the stent. At human body temperature, the stent is fully restore its shape after removing the deforming load. The resulting graph of loading of stents during their compression between parallel plates. The research results allow the conclusion that Si-doped stents are promising for treatment of peripheral vascular disease. However, related studies on laboratory animals are required.

  4. Expandable polyester silicon-covered stent for malignant esophageal strictures before neoadjuvant chemoradiation: a pilot study.

    PubMed

    Siddiqui, Ali A; Loren, David; Dudnick, Robert; Kowalski, Thomas

    2007-03-01

    Patients with resectable esophageal cancer often require placement of a surgical jejunostomy tube prior to receiving chemoradiation so as to maintain adequate nutrition due to their inability to swallow and eat. This study reports a single institutional experience with the Polyflex self-expanding silicone stent (Riisch; Kernen. Germany) in patients with malignant stenosis receiving chemoradiation prior to esophagectomy. This was a retrospective, nonrandomized study of 6 patients who underwent Polyflex esophageal stent placement across a malignant stricture prior to receiving neoadjuvant chemoradiation. The study assessed procedural success, restoration of oral nutrition, migration, and removal of the Polyflex stent. The outcomes measured were the efficacy of treatment, stent-related complications, and changes in the nutritional status of the patient after stent placement. Stent placement was successful in 5 of 6 patients (83%). Restoration of oral nutrition after stent placement occurred in 5 of 5 patients (100%). Migration of the stent into the stomach occurred in 3 patients (60%) without occurrence of gastric outlet obstruction; there was no proximal migration. Stents were successfully removed endoscopically or at the time of esophagectomy. This early experience suggests that the removable silicone Polyflex stent is an effective alternative to a surgical jejunostomy tube for the management of malignant esophageal stenosis in patients for whom neoadjuvant chemoradiation is planned prior to esophagectomy.

  5. Design and modeling balloon-expandable coronary stent for manufacturability

    NASA Astrophysics Data System (ADS)

    Suryawan, D.; Suyitno

    2017-02-01

    Coronary artery disease (CAD) is a disease that caused by narrowing of the coronary artery. The narrowing coronary artery is usually caused by cholesterol-containing deposit (plaque) which can cause a heart attack. CAD is the most common cause mortality in Indonesia. The commonly CAD treatment use the stent to opens or alleviate the narrowing coronary artery. In this study, the stent design is optimized for the manufacturability. Modeling is used to determine the free stent expansion due to applied pressure in the inner surface of the stent. The stress distribution, outer diameter change, and dogboning phenomena are investigated in the simulation. The result of modeling and simulating was analyzed and used to optimize the stent design before it is manufactured using EDM (Electric Discharge Machine) in the next research.

  6. The effect of paclitaxel-eluting covered metal stents versus covered metal stents in a rabbit esophageal squamous carcinoma model

    PubMed Central

    Zhang, Yin; Ma, Limei; Huang, Jin; Shuang, Jinquan

    2017-01-01

    Background The use of self-expanding metallic stents (SEMSs) is the current treatment of choice for malignant gastrointestinal obstructions. However, these stents can promote only drainage and have no antitumor effect. Some studies have reported that drug-eluting SEMSs may have tumor inhibition potential. The aim of this study was to evaluate the efficiency and safety of paclitaxel-eluting SEMSs (PEMSs) in rabbit esophageal cancer models. Materials and methods A PEMS was covered with a paclitaxel-incorporated membrane, in which the concentration of paclitaxel was 10% (wt/vol). The rabbit models were created endoscopically. Then, a PEMS or SEMS was endoscopically inserted into the rabbit esophagus. Two weeks after stent placement, the rabbits were sacrificed, and we evaluated the tumor volume, area of the wall defect, area of the tumor under endoscopic ultrasound (EUS) before and after stent placement, status of the proximal esophageal obstruction, tumor metastasis food-intake and weight loss. Results A total of 26 rabbits received stent insertion and survived until sacrifice, and migration occurred in 4 cases, 3 in SEMS group and 1 in PEMS group. For the remaining 22 rabbits, at the sacrificed time, the average tumor volume was 7.00±4.30 cm3 in the SEMS group and 0.94±1.51 cm3 in the PEMS group (P<0.05). The area of the esophageal wall defect was 0.70±0.63 cm2 in the SEMS group and 0.17±0.16 cm2 in the PEMS group (P<0.05). The tumor area under EUS was 4.40±1.47 cm2 in the SEMS group and 1.30±1.06 cm2 in the PEMS group (P<0.05). At the time of stent placement, tumor area under EUS was comparable in the two groups. Other indices did not significantly differ between the two groups. Conclusions SEMS and PEMS are both safe and effective to relieve dysphagia in rabbit esophageal cancer models. A PEMS can serve as an alternative tool for advanced esophageal cancer that may inhibit tumor growth by serving as a drug sustained-release platform. Clinical trials of the

  7. Biodegradable metals for cardiovascular stent application: interests and new opportunities.

    PubMed

    Moravej, Maryam; Mantovani, Diego

    2011-01-01

    During the last decade, biodegradable metallic stents have been developed and investigated as alternatives for the currently-used permanent cardiovascular stents. Degradable metallic materials could potentially replace corrosion-resistant metals currently used for stent application as it has been shown that the role of stenting is temporary and limited to a period of 6-12 months after implantation during which arterial remodeling and healing occur. Although corrosion is generally considered as a failure in metallurgy, the corrodibility of certain metals can be an advantage for their application as degradable implants. The candidate materials for such application should have mechanical properties ideally close to those of 316L stainless steel which is the gold standard material for stent application in order to provide mechanical support to diseased arteries. Non-toxicity of the metal itself and its degradation products is another requirement as the material is absorbed by blood and cells. Based on the mentioned requirements, iron-based and magnesium-based alloys have been the investigated candidates for biodegradable stents. This article reviews the recent developments in the design and evaluation of metallic materials for biodegradable stents. It also introduces the new metallurgical processes which could be applied for the production of metallic biodegradable stents and their effect on the properties of the produced metals.

  8. Biodegradable Metals for Cardiovascular Stent Application: Interests and New Opportunities

    PubMed Central

    Moravej, Maryam; Mantovani, Diego

    2011-01-01

    During the last decade, biodegradable metallic stents have been developed and investigated as alternatives for the currently-used permanent cardiovascular stents. Degradable metallic materials could potentially replace corrosion-resistant metals currently used for stent application as it has been shown that the role of stenting is temporary and limited to a period of 6–12 months after implantation during which arterial remodeling and healing occur. Although corrosion is generally considered as a failure in metallurgy, the corrodibility of certain metals can be an advantage for their application as degradable implants. The candidate materials for such application should have mechanical properties ideally close to those of 316L stainless steel which is the gold standard material for stent application in order to provide mechanical support to diseased arteries. Non-toxicity of the metal itself and its degradation products is another requirement as the material is absorbed by blood and cells. Based on the mentioned requirements, iron-based and magnesium-based alloys have been the investigated candidates for biodegradable stents. This article reviews the recent developments in the design and evaluation of metallic materials for biodegradable stents. It also introduces the new metallurgical processes which could be applied for the production of metallic biodegradable stents and their effect on the properties of the produced metals. PMID:21845076

  9. Paraffin processing of stented arteries using a postfixation dissolution of metallic and polymeric stents.

    PubMed

    Fishbein, Ilia; Welch, Tre; Guerrero, David T; Alferiev, Ivan S; Adamo, Richard F; Chorny, Michael; Gupte, Rohit K; Tang, Yanqing; Levy, Robert J

    Studying the morphology of the arterial response to endovascular stent implantation requires embedding the explanted stented artery in rigid materials such as poly(methyl methacrylate) to enable sectioning through both the in situ stent and the arterial wall, thus maintaining the proper anatomic relationships. This is a laborious, time-consuming process. Moreover, the technical quality of stained plastic sections is typically suboptimal and, in some cases, precludes immunohistochemical analysis. Here we describe a novel technique for dissolution of metallic and plastic stents that is compatible with subsequent embedding of "destented" arteries in paraffin, fine sectioning, major staining protocols, and immunohistochemistry.

  10. Non-polymeric coatings to control drug release from metallic coronary stents

    NASA Astrophysics Data System (ADS)

    Gupta, Celia Edith Macias

    Percutaneous transluminal coronary angiography (PTCA) is a procedure used to re-open narrowed coronary arteries. During PTCA, a coronary stent is expanded inside a diseased vessel and serves as a scaffold to keep the artery open. The major drawback of stenting is restenosis---a re-narrowing of the vessel resulting from the hyperproliferation of smooth muscle cells. Drug eluting stents (DES) reduce the rate of restenosis compared to bare metal stents. Paclitaxel (PAT) is commonly used in DES for its ability to prevent restenosis. However, DES have been associated with thrombosis due to the polymer carrier that controls drug delivery. Therefore, there is a need to change the drug delivery mechanisms to eliminate the need of polymers. The goal of this dissertation is to develop a novel polymer-free drug eluting stent that controls drug release using nanoscale metal coatings. The coating was designed to release PAT as the metal slowly degrades in biological conditions. Once all the Paclitaxel has eluted from the surface, the coating will continue to degrade until the final result is a bare metal stent. The results of this study include a novel non-polymeric drug delivery system using nanoscale coatings that release Paclitaxel at a rate similar to commercial stents, as well as the biocompatibility and efficacy of these coatings. The non-polymeric drug delivery system described here achieved a Paclitaxel release profile equivalent to clinically available Paclitaxel-eluting stents and effectively inhibits smooth muscle cell proliferation, thereby completely eliminating the need for polymers to control drug release from coronary stents.

  11. Bench-top Comparison of Physical Properties of 4 Commercially-Available Self-Expanding Intracranial Stents

    PubMed Central

    Cho, Su-hee; Jo, Won-il; Jo, Ye-eun; Yang, Ku Hyun; Park, Jung Cheol

    2017-01-01

    Purpose To better understand the performance of four commercially available neurovascular stents in intracranial aneurysm embolization, the stents were compared in terms of their basic morphological and mechanical properties. Materials and Methods Four different types of stents that are currently being used for cerebral aneurysm embolization were prepared (two stents per type). Two were laser-cut stents (Neuroform and Enterprise) and two were braided from a single nitinol wire (LEO and LVIS stents). All were subjected to quantitative measurements of stent size, pore density, metal coverage, the force needed to load, push, and deploy the stent, radial force on deployment, surface roughness, and corrosion resistance. Results Compared to their nominal diameters, all stents had greater diameters after deployment. The length generally decreased after deployment. This was particularly marked in the braided stents. The braided stents also had higher pore densities than the laser-cut stents. Metal coverage was highest in the LEO stent (14%) and lowest in the Enterprise stent (5%). The LIVS stent had the highest microcatheter loading force (81.5 gf). The LEO stent had the highest passage force (55.0 gf) and deployment force (78.9 gf). The LVIS and LEO stents had the highest perpendicular (37.1 gf) and circumferential (178.4 gf) radial forces, respectively. The Enterprise stent had the roughest stent wire, followed by the LVIS, LEO, and Neuroform stents. Conclusion The four neurovascular stent types differed in terms of morphological and physical characteristics. An understanding of this diversity may help to decide which stent is most suitable for specific clinical situations. PMID:28316867

  12. Enteral metallic stenting by balloon enteroscopy for obstruction of surgically reconstructed intestine.

    PubMed

    Nakahara, Kazunari; Okuse, Chiaki; Matsumoto, Nobuyuki; Suetani, Keigo; Morita, Ryo; Michikawa, Yosuke; Ozawa, Shun-ichiro; Hosoya, Kosuke; Kobayashi, Shinjiro; Otsubo, Takehito; Itoh, Fumio

    2015-06-28

    We present three cases of self-expandable metallic stent (SEMS) placement using a balloon enteroscope (BE) and its overtube (OT) for malignant obstruction of surgically reconstructed intestine. A BE is effective for the insertion of an endoscope into the deep bowel. However, SEMS placement is impossible through the working channel, because the working channel of BE is too small and too long for the stent device. Therefore, we used a technique in which the BE is inserted as far as the stenotic area; thereafter, the BE is removed, leaving only the OT, and then the stent is placed by inserting the stent device through the OT. In the present three cases, a modification of this technique resulted in the successful placement of the SEMS for obstruction of surgically reconstructed intestine, and the procedures were performed without serious complications. We consider that the present procedure is extremely effective as a palliative treatment for distal bowel stenosis, such as in the surgically reconstructed intestine.

  13. Mechanical Properties of Metallic Stents: How Do These Properties Influence the Choice of Stent for Specific Lesions?

    SciTech Connect

    Dyet, John F.; Watts, William G.; Ettles, Duncan F.; Nicholson, Anthony A.

    2000-01-15

    Purpose: To assess selected balloon-expandable and self-expanding stents for radial force, flexibility, radio-opacity, and trackability, and to relate these physical characteristics to potential indications for placement.Methods: Force-strain curves were plotted for each stent and the force required to produce 50% luminal narrowing was recorded. The ability of the stent to show elastic recoil following deformation was also noted. Flexibility was measured by bending the stents against a force transducer and recording the force required per degree of flexion. Radio-opacity was measured by comparing each stent against a standard aluminum step wedge. Trackability was measured by testing the ability of the stent on its delivery system to track over angles of 90 deg. and 60 deg. Results: The balloon-expandable stents showed greater radial strength and radio-opacity but, apart from the AVE Iliac Bridge stent, showed poorer flexibility and trackability. The self-expanding stents showed less radial force but were able to re-expand following deformity. They were generally more flexible and had better trackability but lower radio-opacity.Conclusion: There is no stent which exhibits all the ideal properties required and therefore the interventionist will need to keep a range of stents available if all lesions are to be addressed.

  14. Mechanical modeling of self-expandable stent fabricated using braiding technology.

    PubMed

    Kim, Ju Hyun; Kang, Tae Jin; Yu, Woong-Ryeol

    2008-11-14

    The mechanical behavior of a stent is one of the important factors involved in ensuring its opening within arterial conduits. This study aimed to develop a mechanical model for designing self-expandable stents fabricated using braiding technology. For this purpose, a finite element model was constructed by developing a preprocessing program for the three-dimensional geometrical modeling of the braiding structure inside stents, and validated for various stents with different braiding structures. The constituent wires (Nitinol) in the braided stents were assumed to be superelastic material and their mechanical behavior was incorporated into the finite element software through a user material subroutine (VUMAT in ABAQUS) employing a one-dimensional superelastic model. For the verification of the model, several braided stents were manufactured using an automated braiding machine and characterized focusing on their compressive behavior. It was observed that the braided stents showed a hysteresis between their loading and unloading behavior when a compressive load was applied to the braided tube. Through the finite element analysis, it was concluded that the current mechanical model can appropriately predict the mechanical behavior of braided stents including such hysteretic behavior, and that the hysteresis was caused by the slippage between the constituent wires and their superelastic property.

  15. DISCOVER: Dutch Iliac Stent trial: COVERed balloon-expandable versus uncovered balloon-expandable stents in the common iliac artery: study protocol for a randomized controlled trial

    PubMed Central

    2012-01-01

    Background Iliac artery atherosclerotic disease may cause intermittent claudication and critical limb ischemia. It can lead to serious complications such as infection, amputation and even death. Revascularization relieves symptoms and prevents these complications. Historically, open surgical repair, in the form of endarterectomy or bypass, was used. Over the last decade, endovascular repair has become the first choice of treatment for iliac arterial occlusive disease. No definitive consensus has emerged about the best endovascular strategy and which type of stent, if any, to use. However, in more advanced disease, that is, long or multiple stenoses or occlusions, literature is most supportive of primary stenting with a balloon-expandable stent in the common iliac artery (Jongkind V et al., J Vasc Surg 52:1376-1383,2010). Recently, a PTFE-covered balloon-expandable stent (Advanta V12, Atrium Medical Inc., Hudson, NH, USA) has been introduced for the iliac artery. Covering stents with PTFE has been shown to lead to less neo-intimal hyperplasia and this might lower restenosis rates (Dolmatch B et al. J Vasc Interv Radiol 18:527-534,2007, Marin ML et al. J Vasc Interv Radiol 7:651-656,1996, Virmani R et al. J Vasc Interv Radiol 10:445-456,1999). However, only one RCT, of mediocre quality has been published on this stent in the common iliac artery (Mwipatayi BP et al. J Vasc Surg 54:1561-1570,2011, Bekken JA et al. J Vasc Surg 55:1545-1546,2012). Our hypothesis is that covered balloon-expandable stents lead to better results when compared to uncovered balloon-expandable stents. Methods/Design This is a prospective, randomized, controlled, double-blind, multi-center trial. The study population consists of human volunteers aged over 18 years, with symptomatic advanced atherosclerotic disease of the common iliac artery, defined as stenoses longer than 3 cm and occlusions. A total of 174 patients will be included. The control group will undergo endovascular dilatation or

  16. Fracture and Collapse of Balloon-Expandable Stents in the Bilateral Common Iliac Arteries Due to Shiatsu Massage

    SciTech Connect

    Ichihashi, Shigeo Higashiura, Wataru; Itoh, Hirofumi; Sakaguchi, Shoji; Kichikawa, Kimihiko

    2012-12-15

    We report a case of stent fracture and collapse of balloon-expandable stents caused by shiatsu massage. A 76-year-old man presented with complaints of intermittent claudication of the right lower extremity. Stenoses of the bilateral common iliac arteries (CIAs) were detected. Balloon-expandable stents were deployed in both CIAs, resulting in resolution of symptoms. Five months later, pelvis x-ray showed collapse of both stents. Despite the stent collapse, the patient was asymptomatic, and his ankle brachial index values were within the normal range. Further history showed that the patient underwent daily shiatsu therapy in the umbilical region, which may have triggered collapse of the stent. Physicians should advise patients to avoid compression of the abdominal wall after implantation of a stent in the iliac artery.

  17. Bare Metal Stenting for Endovascular Exclusion of Aortic Arch Thrombi

    SciTech Connect

    Mahnken, Andreas H.; Hoffman, Andras; Autschbach, Ruediger; Damberg, Anneke L. M.

    2013-08-01

    BackgroundAortic thrombi in the ascending aorta or aortic arch are rare but are associated with a relevant risk of major stroke or distal embolization. Although stent grafting is commonly used as a treatment option in the descending aorta, only a few case reports discuss stenting of the aortic arch for the treatment of a thrombus. The use of bare metal stents in this setting has not yet been described.MethodsWe report two cases of ascending and aortic arch thrombus that were treated by covering the thrombus with an uncovered stent. Both procedures were performed under local anesthesia via a femoral approach. A femoral cutdown was used in one case, and a total percutaneous insertion was possible in the second case.ResultsBoth procedures were successfully performed without any periprocedural complications. Postoperative recovery was uneventful. In both cases, no late complications or recurrent embolization occurred at midterm follow-up, and control CT angiography at 1 respectively 10 months revealed no stent migration, freely perfused supra-aortic branches, and no thrombus recurrence.ConclusionTreating symptomatic thrombi in the ascending aorta or aortic arch with a bare metal stent is feasible. This technique could constitute a minimally invasive alternative to a surgical intervention or complex endovascular therapy with fenestrated or branched stent grafts.

  18. Development of tissue-engineered self-expandable aortic stent grafts (Bio stent grafts) using in-body tissue architecture technology in beagles.

    PubMed

    Kawajiri, Hidetake; Mizuno, Takeshi; Moriwaki, Takeshi; Ishibashi-Ueda, Hatsue; Yamanami, Masashi; Kanda, Keiichi; Yaku, Hitoshi; Nakayama, Yasuhide

    2015-02-01

    In this study, we aimed to describe the development of tissue-engineered self-expandable aortic stent grafts (Bio stent graft) using in-body tissue architecture technology in beagles and to determine its mechanical and histological properties. The preparation mold was assembled by insertion of an acryl rod (outer diameter, 8.6 mm; length, 40 mm) into a self-expanding nitinol stent (internal diameter, 9.0 mm; length, 35 mm). The molds (n = 6) were embedded into the subcutaneous pouches of three beagles for 4 weeks. After harvesting and removing each rod, the excessive fragile tissue connected around the molds was trimmed, and thus tubular autologous connective tissues with the stent were obtained for use as Bio stent grafts (outer diameter, approximately 9.3 mm in all molds). The stent strut was completely surrounded by the dense collagenous membrane (thickness, ∼150 µm). The Bio stent graft luminal surface was extremely flat and smooth. The graft wall of the Bio stent graft possessed an elastic modulus that was almost two times higher than that of the native beagle abdominal aorta. This Bio stent graft is expected to exhibit excellent biocompatibility after being implanted in the aorta, which may reduce the risk of type 1 endoleaks or migration.

  19. Current state of the absorbable metallic (magnesium) stent.

    PubMed

    Waksman, Ron

    2009-12-15

    BIOTRONIK's absorbable metal stent technology is based ona magnesium alloy that offers superior stent mechanics and biocompatibility. The first generation (AMS-1) showed promising results regarding mechanical properties as well as feasibility and safety in several human applications (150 cases). The second generation (AMS-2.1) shows improved scaffolding and efficacy in animals due to a more slowly degrading magnesium alloy and an optimised stent design. The preclinical results of the drug-eluting AMS-3 are encouraging and the clinical investigational program will resume in 2010.

  20. Malignant Ureteral Obstruction: Functional Duration of Metallic versus Polymeric Ureteral Stents

    PubMed Central

    Chow, Po-Ming; Chiang, I-Ni; Chen, Chia-Yen; Huang, Kuo-How; Hsu, Jui-Shan; Wang, Shuo-Meng; Lee, Yuan-Ju; Yu, Hong-Jeng; Pu, Yeong-Shiau; Huang, Chao-Yuan

    2015-01-01

    Background Ureteral obstruction caused by extrinsic compression is often associated with intra-abdominal cancers. Internal drainage with ureteral stents is typically the first-line therapy to relieve such obstructions. Novel designs of ureteral stents made of different materials have been invented to achieve better drainage. In this study, we described the functional outcomes of a Resonance metallic ureteral stent (Cook Medical, Bloomington, Indiana, USA) in patients with malignant ureteral obstruction and compare the functional duration of Resonance stents with regular polymeric stents in the same cohort. Methods Cancer patients who received polymeric stents and subsequent Resonance stents for ureteral obstruction between July 2009 and November 2012 were included in a chart review. Stent failure was detected by clinical symptoms, imaging studies, and renal function tests. The functional durations of each stent were calculated, and possible factors affecting stent patency were investigated. Results A total of 50 stents were successfully inserted into 50 ureteral units in 42 patients with malignant ureteral obstruction. There were 7 antegrade stents and 43 retrograde stents. There were no major complications. Stent-related symptoms were similar in both kinds of stents. After polymeric stents were replaced with Resonance metallic stents, hydronephrosis subsided or remained stable in 90% (45/50) of the ureteral units. Serum creatinine decreased or remained stable in 90% (38/42) of these patients. The Resonance stent exhibited a mean increase in functional duration of 4 months compared with the polymeric stents (p<0.0001), and 50% (25/50) of the Resonance stents exhibited a significant increase in functional duration (more than 3 months). Pre-operative serum creatinine < 2 was associated with a substantial increase in stent duration. Conclusions Resonance stents are effective and safe in relieving malignant ureteral obstructions after polymeric stents failure

  1. Effect of a paclitaxel-eluting metallic stent on rabbit esophagus

    PubMed Central

    Zhang, Yin; Gao, Ying; Chen, Jianping; Ma, Limei; Liu, Li; Wang, Xiang; Fan, Zhining

    2016-01-01

    The use of self-expanding metallic stents (SEMS) is the current treatment of choice for malignant gastrointestinal obstructions. A paclitaxel-eluting metallic SEMS (PEMS) may have an antitumor effect on esophageal tissue. PEMS with 10% paclitaxel or conventional SEMS were inserted into the lower esophagus of rabbits. Following the insertion of the stents for 1, 2, 4 and 6 weeks, the rabbits were sacrificed and the status of the stent insertion was examined, as well as any macroscopic or microscopic mucosal changes in the esophageal tissue. All the rabbits survived until death without any complications. No migration following stent insertion occurred. The number of cases with proximal obstruction increased in a time-dependent manner, and no significant difference was observed between the two groups. Gross histological examination showed similar tissue reaction to the stents at 1, 2 and 4 weeks, and inflammatory cell infiltrating was higher in the SEMS group at 1 and 2 weeks. However, inflammatory cell infiltration was markedly higher in the PEMS group at 4 and 6 weeks. Food-intake and weight were similar in the two groups. The results of the present study demonstrated that PEMS may serve as a safe alternative treatment strategy for esophageal obstruction. Furthermore, PEMS may inhibit the tumor growth of the esophageal wall through inflammatory infiltration and targeted drug delivery. A tumor model will be required in the future for evaluating the prognosis of patients with advanced esophageal carcinoma. PMID:27882097

  2. Management of Failing Prosthetic Bypass Grafts with Metallic Stent Placement

    SciTech Connect

    Siskin, Gary P.; Stainken, Brian F.; Mandell, Valerie S.; Darling, R. Clement; Dowling, Kyran; Herr, Allen

    1999-09-15

    Purpose: To evaluate the role of metallic stents in treating stenoses involving prosthetic arterial bypass grafts. Methods: Patients undergoing stent placement within a failing prosthetic bypass graft, during a 41-month period, were reviewed for treatment outcome and complications. The indications for stent placement in 15 patients included severe claudication (n= 3), rest pain (n= 9), and minor or major tissue loss (n= 3). Lesions were at the proximal anastomosis (n= 6), the distal anastomosis (n= 3), or within the graft (n= 6). Results: Treatment with metallic stents was successful in all patients. There was one acute stent thrombosis, successfully treated with thrombolytic therapy. Follow-up data are available for a mean duration of 12.3 months. The mean duration of primary patency was 9.4 months with 6- and 12-month primary patency rates of 51.9% and 37.0%, respectively. The mean duration of secondary patency was 12.1 months with 6- and 12-month secondary patency rates of 80.0% and 72.7%, respectively. Two patients with discontinuous runoff and preexisting gangrene required a below-knee amputation. Six patients were revised surgically after stent placement (at a mean of 10.8 months). Three late deaths occurred during follow-up. Conclusion: Given the mortality risks of surgical revision and the reduced life expectancy of this patient population, metallic stent placement represents a viable, short-term treatment option for stenoses within or at the anastomoses of prosthetic grafts. Further evaluation is warranted to compare intragraft stent placement with surgical graft revision.

  3. Drug-eluting versus bare-metal coronary stents: where are we now?

    PubMed

    Amoroso, Nicholas S; Bangalore, Sripal

    2012-11-01

    Drug-eluting stents have dramatically reduced the risk of restenosis, but concerns of an increased risk of stent thrombosis have provided uncertainty about their use. Recent studies have continued to show improved procedural and clinical outcomes with drug-eluting stents both in the setting of acute coronary syndromes and stable coronary artery disease. Newer generation drug-eluting stents (especially everolimus-eluting stents) have been shown to be not only efficacious but also safe with reduced risk of stent thrombosis when compared with bare-metal stents, potentially changing the benchmark for stent safety from bare-metal stents to everolimus-eluting stents. While much progress is being made in the development of bioabsorbable polymer stents, nonpolymer stents and bioabsorbable stent technology, it remains to be seen whether these stents will have superior safety and efficacy outcomes compared with the already much improved rates of revascularization and stent thrombosis seen with newer generation stents (everolimus-eluting stents and resolute zotarolimus-eluting stents).

  4. Endoscopic stenting for hilar cholangiocarcinoma: efficacy of unilateral and bilateral placement of plastic and metal stents in a retrospective review of 480 patients

    PubMed Central

    2012-01-01

    Background Endoscopic biliary drainage of hilar cholangiocarcinoma is controversial with respect to the optimal types of stents and the extent of drainage. This study evaluated endoscopic palliation in patients with hilar cholangiocarcinoma using self-expandable metallic stents (SEMS) and plastic stents (PS).We also compared unilateral and bilateral stent placement according to the Bismuth classification. Methods Data on 480 patients receiving endoscopic biliary drainage for hilar cholangiocarcinoma between September 1995 and December 2010 were retrospectively reviewed to evaluate the following outcome parameters: technical success (TS), functional success (FS), early and late complications, stent patency and survival. Patients were followed from stent insertion until death or stent occlusion. Patients were divided into 3 groups according to the Bismuth classification (Group 1, type I; Group 2, type II; Group 3, type > III). Results The initial stent insertion was successful in 450 (93.8%) patients. TS was achieved in 204 (88.3%) patients treated with PS and in 246 (98.8%) patients palliated with SEMS (p < 0.001). In the intention-to-treat (ITT) analysis, the FS in patients treated with SEMS (97.9%) was significantly higher than in patients treated with PS (84.8%) (p < 0.001). Late complications occurred in 115 (56.4%) patients treated with PS and 60 (24.4%) patients treated with SEMS (p < 0.001). The median duration of stent patency in weeks (w) were as follows: 20 w in patients palliated with PS and 27 w in patients treated with SEMS (p < 0.0001). In Group 2, the median duration of PS patency was 17 w and 18 w for unilateral and bilateral placement, respectively (p = 0.0004); the median duration of SEMS patency was 24 w and 29 w for unilateral and bilateral placement, respectively (p < 0.0001). Multivariate analysis using the Poisson regression showed that SEMS placement (B = 0.48; P < 0.01) and bilateral deployment (B = 0

  5. Mechanical Characteristics of Composite Knitted Stents

    SciTech Connect

    Tokuda, Takanori Shomura, Yuzo; Tanigawa, Noboru; Kariya, Shuji; Komemushi, Atsushi; Kojima, Hiroyuki; Sawada, Satoshi

    2009-09-15

    We used metal wires and fibers to fabricate a composite knitted stent and then compare the mechanical characteristics of this stent with those of a pure metallic stent of the same construction in order to develop a stent that offers a comparable degree of expandability as metallic stents but can be used for highly curved lesions that cannot be treated using metallic stents. We fabricated two types of composite knitted stent (N-Z stents), using nitinol wire with a diameter of 0.12 mm and polypara-phenylene-benzobisoxazole (PBO) multifilament fiber (Zyron AS; Toyobo, Osaka, Japan). Stents were knitted into a cylindrical shape using the same textile pattern as a Strecker stent. Two loop lengths (L) of nitinol wire were used in the N-Z stents: L = 1.84 mm (N-Z stent L = 1.84) and L = 2.08 mm (N-Z stent L = 2.08). For the sake of comparison, we fabricated a metallic stent of nitinol using the same textile pattern (N-N stent L = 1.92). We applied a radial compression force diametrically to each stent and applied a bending force diametrically at the free end of a stent with one end fixed in order to evaluate the relationship between stent elasticity and load values. In addition, we macroscopically evaluated the generation of kinks when the stent was bent 180{sup o}. The radial compressive force when the stent diameter was reduced by 53% was 6.44 N in the case of N-Z stent L = 1.84, 6.14 N in the case of N-Z stent L = 2.08, and 4.96 N in the case of N-N stent L = 1.92 mm. The composite stent had a radial compressive force higher than that of a metallic stent. The restoring force to longitudinal direction at a 90{sup o} bending angle was 0.005 N for N-Z stent L = 1.84, 0.003 N for N-Z stent L = 2.08, and 0.034 N for N-N stent L = 1.92. The restoring force of the composite stent was significantly lower. Finally, the composite stent generated no definitive kinks at a bending angle of 180{sup o}, regardless of loop length. However, the N-N stent clearly produced kinks, causing

  6. Antireflux Metal Stent as a First-Line Metal Stent for Distal Malignant Biliary Obstruction: A Pilot Study

    PubMed Central

    Hamada, Tsuyoshi; Isayama, Hiroyuki; Nakai, Yousuke; Togawa, Osamu; Takahara, Naminatsu; Uchino, Rie; Mizuno, Suguru; Mohri, Dai; Yagioka, Hiroshi; Kogure, Hirofumi; Matsubara, Saburo; Yamamoto, Natsuyo; Ito, Yukiko; Tada, Minoru; Koike, Kazuhiko

    2017-01-01

    Background/Aims In distal malignant biliary obstruction, an antireflux metal stent (ARMS) with a funnel-shaped valve is effective as a reintervention for metal stent occlusion caused by reflux. This study sought to evaluate the feasibility of this ARMS as a first-line metal stent. Methods Patients with nonresectable distal malignant biliary obstruction were identified between April and December 2014 at three Japanese tertiary centers. We retrospectively evaluated recurrent biliary obstruction and adverse events after ARMS placement. Results In total, 20 consecutive patients were included. The most common cause of biliary obstruction was pancreatic cancer (75%). Overall, recurrent biliary obstruction was observed in seven patients (35%), with a median time to recurrent biliary obstruction of 246 days (range, 11 to 246 days). Stent occlusion occurred in five patients (25%), the causes of which were sludge and food impaction in three and two patients, respectively. Stent migration occurred in two patients (10%). The rate of adverse events associated with ARMS was 25%: pancreatitis occurred in three patients, cholecystitis in one and liver abscess in one. No patients experienced non-occlusion cholangitis. Conclusions The ARMS as a first-line biliary drainage procedure was feasible. Because the ARMS did not fully prevent stent dysfunction due to reflux, further investigation is warranted. PMID:27282268

  7. Fabrication of a silver particle-integrated silicone polymer-covered metal stent against sludge and biofilm formation and stent-induced tissue inflammation

    PubMed Central

    Lee, Tae Hoon; Jang, Bong Seok; Jung, Min Kyo; Pack, Chan Gi; Choi, Jun-Ho; Park, Do Hyun

    2016-01-01

    To reduce tissue or tumor ingrowth, covered self-expandable metal stents (SEMSs) have been developed. The effectiveness of covered SEMSs may be attenuated by sludge or stone formation or by stent clogging due to the formation of biofilm on the covering membrane. In this study, we tested the hypothesis that a silicone membrane containing silver particles (Ag-P) would prevent sludge and biofilm formation on the covered SEMS. In vitro, the Ag-P-integrated silicone polymer-covered membrane exhibited sustained antibacterial activity, and there was no definite release of silver ions from the Ag-P-integrated silicone polymer membrane at any time point. Using a porcine stent model, in vivo analysis demonstrated that the Ag-P-integrated silicone polymer-covered SEMS reduced the thickness of the biofilm and the quantity of sludge formed, compared with a conventional silicone-covered SEMS. In vivo, the release of silver ions from an Ag-P-integrated silicone polymer-covered SEMS was not detected in porcine serum. The Ag-P-integrated silicone polymer-covered SEMS also resulted in significantly less stent-related bile duct and subepithelium tissue inflammation than a conventional silicone polymer-covered SEMS. Therefore, the Ag-P-integrated silicone polymer-covered SEMS reduced sludge and biofilm formation and stent-induced pathological changes in tissue. This novel SEMS may prolong the stent patency in clinical application. PMID:27739486

  8. Finite element analysis of balloon-expandable coronary stent deployment: influence of angioplasty balloon configuration.

    PubMed

    Martin, David; Boyle, Fergal

    2013-11-01

    Today, the majority of coronary stents are balloon-expandable and are deployed using a balloon-tipped catheter. To improve deliverability, the membrane of the angioplasty balloon is typically folded about the catheter in a pleated configuration. As such, the deployment of the angioplasty balloon is governed by the material properties of the balloon membrane, its folded configuration and its attachment to the catheter. Despite this observation, however, an optimum strategy for modelling the configuration of the angioplasty balloon in finite element studies of coronary stent deployment has not been identified, and idealised models of the angioplasty balloon are commonly employed in the literature. These idealised models often neglect complex geometrical features, such as the folded configuration of the balloon membrane and its attachment to the catheter, which may have a significant influence on the deployment of a stent. In this study, three increasingly sophisticated models of a typical semi-compliant angioplasty balloon were employed to determine the influence of angioplasty balloon configuration on the deployment of a stent. The results of this study indicate that angioplasty balloon configuration has a significant influence on both the transient behaviour of the stent and its impact on the mechanical environment of the coronary artery.

  9. Bronchial artery aneurysm suggested to be caused by metalic tracheal stent migration.

    PubMed

    Sato, Kiyoshi; Fumimoto, Satoshi; Fukada, Takehisa; Ochi, Kaoru; Kataoka, Takayuki; Ichihashi, Yoshio; Satomi, Hidetoshi; Morita, Takuya; Hanaoka, Nobuharu; Okada, Yoshikatsu; Katsumata, Takahiro

    2016-12-01

    Occurrence of bronchial artery aneurysm is rare, and it has been detected in less than 1 % of all selective bronchial arteriography cases. Here, we present a case of a bronchial artery aneurysm caused by a tracheal stent migration. A 59-year-old man was operated on for esophageal cancer, where an esophageal-tracheal fistula occurred 1 week after operation. Surgical repair of the esophageal-tracheal fistula was performed using a muscle flap, but this not results in fistula closure. Consequently, a self-expanding covered metallic tracheal stent was implanted for rescue, and this resulted in fistula closure. After 1 year, there was frequent hemoptysis caused by migration of the stent. He was referred to our hospital where removal of the stent was planned. A sudden occurrence of massive bleeding from trachea occurred, and extracorporeal membrane oxygenation (ECMO) was used. Although removal of tracheal stent was performed successfully, the patient subsequently died from multi-organ failure. Post-mortem autopsy revealed that the massive bleeding is originated from the rupture of a bronchial artery aneurysm.

  10. Will absorbable metal stent technology change our practice?

    PubMed

    Bosiers, M; Deloose, K; Verbist, J; Peeters, P

    2006-08-01

    Peripheral stents aim to support revascularization procedures of intravascular stenoses by mechanically preventing vessel recoil and counteracting pathophysiologic processes of luminal re-narrowing triggered by procedural injury of the vessel wall. Despite improvements in stenting techniques and concomitant medication, repeated intervention due to target lesion re-stenosis is necessary on a significant percentage of patients. The permanent presence of an artificial implant plays a prominent role in the discussion of mechanisms causing in-stent restenosis. Permanent metallic implants pose the risk of a continuous interaction between non-absorbable stent and surrounding tissue, leading to physical irritation, long-term endothelial dysfunction, or chronic inflammatory reactions. In addition, there is a risk of stent fracture due to external mechanical forces. To overcome these shortcomings, technology of stenting has moved towards the development of temporary implants composed of biocompatible materials which mechanically support the vessel during the period of high risk for recoil and then completely degrade in the long-term perspective. This removes a potential trigger for late restenosis.

  11. Long-Term Results after Placement of Aortic Bifurcation Self-Expanding Stents: 10 Year Mortality, Stent Restenosis, and Distal Disease Progression

    SciTech Connect

    Houston, J. Graeme Bhat, Raj; Ross, Rose; Stonebridge, Peter A.

    2007-02-15

    Purpose. To retrospectively evaluate the 10 year follow-up results in patients who had 'kissing' self-expanding stent aortic bifurcation reconstruction. Methods. Forty-three patients were treated with 'kissing' self-expanding stents for aortoiliac occlusive disease. Early follow-up with clinical and ankle brachial pressure indices (ABPI) was performed at 3, 6, 12, and 24 months and with intra-arterial digital subtraction angiography at 12-24 months; clinical and angiographic follow-up was performed for symptom recurrence up to 10 years after treatment. Retrospective record review was performed to assess mortality, clinical patency, angiographic patency, and secondary assisted patency of both stents and downstream peripheral vessels at 5 and 10 years follow-up. Results. The 2 year primary angiographic and secondary assisted stent patencies were 89% and 93%, respectively. At 10 years follow-up in 40 patients the mortality was 38% (due to myocardial infarction, stroke, chronic renal failure, malignancy, and liver failure). At 5 and 10 years follow-up the primary clinical stent patency was 82% and 68%, and the secondary assisted stent patency 93% and 86%, respectively. At 5 and 10 years, the distal vessel patency was 86% and 72%, and the secondary assisted distal vessel patency treated by surgical or endovascular techniques was 94% and 88%, respectively. At 10 years there was no limb loss. Conclusion. The long-term (10 year) results of aortic bifurcation arterial self-expanding stent placement in patients with arterial occlusive disease show a 10 year primary stent patency rate of 68% but a secondary assisted patency rate of 86%. In addition there is a high overall mortality due to other cardiovascular causes and the rate of distal disease progression and loss of patency is similar to the loss of stent patency rate.

  12. Management of Biliary Neoplastic Obstruction with Two Different Metallic Stents Implanted in One Session

    SciTech Connect

    Gandini, Roberto; Fabiano, S. Pipitone, Vincenzo; Spinelli, Alessio; Reale, Carlo Andrea; Colangelo, Vittorio; Pampana, Enrico; Romagnoli, Andrea; Simonetti, Giovanni

    2005-01-15

    The efficacy of the 'one-step' technique using two different metallic stents (Wallstent and Ultraflex) and associated rate of complications was studied in 87 patients with jaundice secondary to malignant biliary obstruction, with bilirubin level less than 15 mg/dl and Bismuth type 1 or 2 strictures. The study group, composed of 40 men and 47 women with a mean age of 59.4 years (range 37-81 years), was treated with a 'one-step' percutaneous transhepatic implantation of self-expanding stents. The cause of the obstruction was pancreatic carcinoma in 38 patients (44%), lymph node metastasis in 20 patients (23%), gallbladder carcinoma in 13 patients (15%), cholangiocarcinoma in 12 patients (14%) and ampullary carcinoma in four patients (5%). A significant reduction in jaundice was obtained in all but one patient, with a drop of total serum bilirubin level from a mean of 13.7 mg/dl to 4.3 mg/dl within the first 4 days. The mean postprocedural hospitalization period was 5.4 days in the Wallstent group and 6.4 days in the Ultraflex group. Mean survival rate was 7.8 months (Wallstent group) and 7.1 months (Ultraflex group). The use of both stents did not reveal any significant difference in parameters tested. The implantation of these self-expandable stents in one session, in selected patients, is clinically effective, devoid of important complications and cost-effective due to the reduction in hospitalization.

  13. ALD mediated heparin grafting on nitinol for self-expanded carotid stents.

    PubMed

    Wang, Fei; Zhang, Yan; Chen, Xiumian; Leng, Bing; Guo, Xin; Zhang, Tao

    2016-07-01

    Carotid-artery atherosclerosis is a common cause of ischemic stroke. Carotid-artery stenting (CAS) is one of the most effective treatments. However, In-stent restenosis (ISR) and re-endothelialization delay are two major issues of intravascular stent which affect clinical safety and reduce effects. In this study, atomic layer deposition (ALD) technology was applied to deposit a layer (10nm) of Al2O3 on Nitinol surface as an intermediate functional layer. The alumina covered surface was then modified with a coupling agent 3-aminopropyltriethoxysilane (APS) and heparin sequentially in order to improve the hemocompatibility of Nitinol stents. The successful graft of APS and heparin onto Nitinol was proven by X-ray photoelectron spectroscopy. Furthermore, the predicted improvement in the biocompatibilities of modified Nitinol was confirmed by water contact angle measurement, protein adsorption, platelet adhesion, and plasma recalcification time determination. The results of hemolysis assay, cell proliferation and cytotoxicity tests revealed that the grafting of heparin on NiTi kept the original positive performance of nitinol material. The results indicate that ALD technology is of great potential for the manufacture of medical devices, especially for surface modifications and functionalization. ALD technology can help with modifications of inert metallic surfaces and therefore benefit implantable medical devices, especially intravascular stents.

  14. Successful technical and clinical outcome using a second generation balloon expandable coronary stent for transplant renal artery stenosis: Our experience

    PubMed Central

    Salsamendi, Jason; Pereira, Keith; Baker, Reginald; Bhatia, Shivank S; Narayanan, Govindarajan

    2015-01-01

    Transplant renal artery stenosis (TRAS) is a vascular complication frequently seen because of increase in the number of renal transplantations. Early diagnosis and management is essential to optimize a proper graft function. Currently, the endovascular treatment of TRAS using angioplasty and/or stenting is considered the treatment of choice with the advantage that it does not preclude subsequent surgical correction. Treatment of TRAS with the use of stents, particularly in tortuous transplant renal anatomy presents a unique challenge to an interventional radiologist. In this study, we present three cases from our practice highlighting the use of a balloon-expandable Multi-Link RX Ultra coronary stent system (Abbott Laboratories, Abbott Park, Illinois, USA) for treating high grade focal stenosis along very tortuous renal arterial segments. Cobalt–Chromium alloy stent scaffold provides excellent radial force, whereas the flexible stent design conforms to the vessel course allowing for optimal stent alignment. PMID:26629289

  15. Mechanical Interaction of an Expanding Coiled Stent with a Plaque-Containing Arterial Wall: A Finite Element Analysis.

    PubMed

    Welch, Tré R; Eberhart, Robert C; Banerjee, Subhash; Chuong, Cheng-Jen

    2016-03-01

    Wall injury is observed during stent expansion within atherosclerotic arteries, related in part to stimulation of the inflammatory process. Wall stress and strain induced by stent expansion can be closely examined by finite element analysis (FEA), thus shedding light on procedure-induced sources of inflammation. The purpose of this work was to use FEA to examine the interaction of a coiled polymer stent with a plaque-containing arterial wall during stent expansion. An asymmetric fibrotic plaque-containing arterial wall model was created from intravascular ultrasound (IVUS) images of a diseased artery. A 3D model for a coil stent at unexpanded state was generated in SolidWorks. They were imported into ANSYS for FEA of combined stent expansion and fibrotic plaque-distortion. We simulated the stent expansion in the plaqued lumen by increasing balloon pressure from 0 to 12 atm in 1 atm step. At increasing pressure, we examined how the expanding stent exerts forces on the fibrotic plaque and vascular wall components, and how the latter collectively resist and balance the expansive forces from the stent. Results show the expanding coiled stent creates high stresses within the plaque and the surrounding fibrotic capsule. Lower stresses were observed in adjacent medial and adventitial layers. High principal strains were observed in plaque and fibrotic capsule. The results suggest fibrotic capsule rupture might occur at localized regions. The FEA/IVUS method can be adapted for routine examination of the effects of the expansion of selected furled stents against IVUS-reconstructed diseased vessels, to improve stent deployment practices.

  16. Successful biliary drainage using a metal stent through the gastric stoma

    PubMed Central

    Matsumoto, Kazuyuki; Kato, Hironari; Tsutsumi, Koichiro; Akimoto, Yutaka; Uchida, Daisuke; Tomoda, Takeshi; Yamamoto, Naoki; Noma, Yasuhiro; Horiguchi, Shigeru; Okada, Hiroyuki; Yamamoto, Kazuhide

    2015-01-01

    We report a case of biliary drainage for malignant stricture using a metal stent with an ultrathin endoscope through the gastric stoma. A 78-year-old female was referred to our hospital for jaundice and fever. She had undergone percutaneous endoscopic gastrostomy (PEG) for esophageal obstruction after radiation therapy for cancer of the pharynx. Abdominal contrast-enhanced computed tomography showed a 3-cm enhanced mass in the middle bile duct and dilatation of the intra-hepatic bile duct. We initially performed endoscopic retrograde cholangiopancreatography (ERCP) with a trans-oral approach. However, neither the side-viewing endoscope nor the ultrathin endoscope passed through the esophageal orifice. Thus, we eventually performed ERCP via the PEG stoma using an ultrathin endoscope. We performed biliary drainage with a 6F introducer self-expanding metal stent. The cytology findings obtained by brush cytology showed malignancy. Her laboratory results were restored to normal levels after drainage and no complication occurred. PMID:26140009

  17. Palliation of Postoperative Gastrointestinal Anastomotic Malignant Strictures with Flexible Covered Metallic Stents: Preliminary Results

    SciTech Connect

    Lee, Jeong-Min; Han, Young Min; Lee, Sang Yong; Kim, Chong Soo; Yang, Doo Hyun; Lee, Seung Ok

    2001-01-15

    Purpose: To evaluate the efficacy of the placement of covered metallic stents for palliation of gastrointestinal anastomotic strictures secondary to recurrent gastric cancer.Methods: Under fluoroscopic guidance, placement of one or two self-expandable covered metallic stents was attempted perorally in 11 patents (aged 48-76 years) with anastomotic stenoses due to recurrent gastric malignancies. The strictures involved both the afferent and efferent loops in three patients. All patients had poor peroral food intake with severe nausea and vomiting after ingestion. The technical and clinical success was evaluated.Results: Placement of the covered stent was technically successful in 13 of 15 (87%) attempts in ten patients. After the procedure, 9 of 11 (82%) patients overall were able to ingest at least a liquid diet and had markedly decreased incidence of vomiting. During the follow-up of 2-31 weeks (mean 8.5 weeks) there were no major complications.Conclusion: These preliminary results suggest that flexible, covered stents may provide effective palliation of malignant anastomotic stricture secondary to recurrent gastric cancer.

  18. Future developments in biliary stenting

    PubMed Central

    Hair, Clark D; Sejpal, Divyesh V

    2013-01-01

    Biliary stenting has evolved dramatically over the past 30 years. Advancements in stent design have led to prolonged patency and improved efficacy. However, biliary stenting is still affected by occlusion, migration, anatomical difficulties, and the need for repeat procedures. Multiple novel plastic biliary stent designs have recently been introduced with the primary goals of reduced migration and improved ease of placement. Self-expandable bioabsorbable stents are currently being investigated in animal models. Although not US Food and Drug Administration approved for benign disease, fully covered self-expandable metal stents are increasingly being used in a variety of benign biliary conditions. In malignant disease, developments are being made to improve ease of placement and stent patency for both hilar and distal biliary strictures. The purpose of this review is to describe recent developments and future directions of biliary stenting. PMID:23837001

  19. Feasibility study for the investigation of Nitinol self-expanding stents by neutron techniques

    NASA Astrophysics Data System (ADS)

    Rogante, M.; Pasquini, U.; Rosta, L.; Lebedev, V.

    2011-02-01

    In this paper, neutron techniques - in particular, small angle neutron scattering (SANS) and neutron diffraction (ND) - are considered for the non-destructive characterization of Nitinol artery stents. This roughly equiatomic (50Ni-50Ti at%) shape memory alloy (SMA) exhibits significant properties of superelasticity and biocompatibility that make it suitable to be typically used as smart material for medical implants and devices. Nitinol self-expanding artery stents, as permanent vascular support structures, supply an ideal option to bypass surgery, but they are submitted for the whole of patient's life to the dynamical stress of the artery pulsation and the aggression from the biological environment. These stents, consequently, can suffer from wear and fracture occurrence likely due to a variety of cyclic fatigue, overload conditions and residual stresses. Neutrons have recently become a progressively more important probe for various materials and components and they allow achieving information complementary to those obtained from the traditional microstructural analyses. The outputs from the preliminary works already carried out in this field consent to consider neutron techniques capable to contribute to the development of these crucial medical implants. The achievable results can yield trends adoptable in monitoring of the stent features.

  20. The Integrity bare-metal stent made by continuous sinusoid technology.

    PubMed

    Turco, Mark A

    2011-05-01

    The Integrity Coronary Stent System (Medtronic Vascular, CA, USA) is a low-profile, open-cell, cobalt-chromium-alloy advanced bare-metal iteration of the well-known Driver/Micro-Driver Coronary Stent System (Medtronic Vascular). The Integrity stent is made with a process called continuous sinusoid technology. This process allows stent construction via wrapping a single thin strand of wire around a mandrel in a sinusoid configuration, with laser fusion of adjacent crowns. The wire-forming process and fusion pattern provide the stent with a continuous preferential bending plane, intended to allow easier access to, and smoother tracking within, distal and tortuous vessels while radial strength is maintained. Continuous sinusoid technology represents innovation in the design of stent platforms and will provide a future stent platform for newer technology, including drug-eluting stent platforms, drug-filled stents and core wire stents.

  1. Gastrointestinal Stent Update

    PubMed Central

    2010-01-01

    The use of self-expanding metallic stents in the upper gastrointestinal tract, placed under radiologic imaging or endoscopic guidance, is the current treatment of choice for the palliation of malignant gastrointestinal outlet obstructions. Advances in metallic stent design and delivery systems have progressed to the stage where this treatment is now considered a minimally invasive therapy. Metallic stent placement will broaden further into the field of nonsurgical therapy for the gastrointestinal tract. To date, metallic stents placed in the esophagus, gastric outlet, colorectum, and bile ducts are not intended to be curative, but rather to provide a palliative treatment for obstructions. The evolution of metallic stent technology will render such procedures not only palliative but also therapeutic, by enabling local drug delivery, and the use of biodegradable materials will reduce procedure-related complications. PMID:21103290

  2. The use of cold sprayed alloys for metallic stents

    NASA Astrophysics Data System (ADS)

    AL-Mangour, Bandar

    With the invention of the coronary stent, which is a wire metal mesh tube designed to keep the arteries open in the treatment of heart diseases, promising clinical outcomes were generated. However, the long term successes of stents have been delayed by significant in-stent restenosis (blockages) and stent fracture. In this research work, it has been proposed to use Cold Gas Dynamic Spraying (CGDS) coating material as an alternative choice to manufacture metallic stent. In CGDS, fine particles are accelerated to a high velocity and undergo solid-state plastic deformation upon impact on the substrate, which leads to particle-particle bonding. The feature of CGDS distinct from other thermal spray techniques is that the processing gas temperature is below the melting point of the feedstock. Therefore, unwanted effects of high temperatures, such as oxidation, grain growth and thermal stresses, are absent. In response to the fact that the majority of stents are made from stainless steel (316L) or Co-Cr alloy (L605), this study specifically addresses the development and characterization of 316L and 316L mixed with L605 coatings produced by the CGDS process. Scanning electron microscopy and electron backscatter diffraction were used to investigate the microstructural changes of these coatings before and after annealing. The effect of gas type on the microstructure of 316L coatings and the role of post-heat treatment in the microstructure and properties are also studied. Of particular interest are grain refinement, heat treatment, mechanical properties and corrosion behavior of the cold sprayed material.

  3. Use of self-expanding stents for better intracranial flow diverter wall apposition.

    PubMed

    Kühn, Anna Luisa; Wakhloo, Ajay K; Gounis, Matthew J; Kan, Peter; de Macedo Rodrigues, Katyucia; Lozano, J Diego; Marosfoi, Miklos G; Perras, Mary; Brooks, Christopher; Howk, Mary C; Rex, David E; Massari, Francesco; Puri, Ajit S

    2017-04-01

    Background Flow diverter (FD) malapposition is associated with stroke-related complications. We document the use of self-expanding nitinol stents to remove/reduce the ledge of a FD deployed for aneurysm treatment. Methods We identified five patients who were treated with the Pipeline embolization device (PED) in conjunction with a Neuroform EZ stent for inadequate wall apposition of the ends of the FD at our institution between May 2014 and July 2015. Among other parameters, angiographic results, cone-beam computed tomography assessment of wall apposition and patient clinical outcome were evaluated. Results Incomplete device end apposition was seen in three cases, and precarious positioning of the distal end of the PED over the aneurysm neck was seen in two cases. In all five cases, successful treatment with good wall apposition and proper pinning of the PED distal edge was achieved using an additional Neuroform EZ stent. Appropriate aneurysm neck coverage and flow stagnation was seen in all cases. The combination of high radial outward force and open-cell design permits the Neuroform EZ stent to jail the malappositioned edges of the FD while maintaining good vessel-wall apposition itself and prevent migration of the PED. Short-term follow-up angiography showed device patency and complete aneurysm obliteration in all cases. Conclusions Preliminary results of this small case series suggest that the Neuroform EZ stent allows for effective treatment of FD malapposition in selected patients amenable for this endovascular approach. Long-term and larger cohort studies are needed to validate these results.

  4. A finite element study of balloon expandable stent for plaque and arterial wall vulnerability assessment

    NASA Astrophysics Data System (ADS)

    Karimi, Alireza; Navidbakhsh, Mahdi; Razaghi, Reza

    2014-07-01

    The stresses induced within plaque tissues and arterial layers during stent expansion inside an atherosclerotic artery can be exceeded from the yield stresses of those tissues and, consequently, lead to plaque or arterial layer rupture. The distribution and magnitude of the stresses in each component involved in stenting might be clearly different for different plaque types and different arterial layers. In this study, a nonlinear finite element simulation was employed to investigate the effect of plaque composition (calcified, cellular, and hypocellular) on the stresses induced in the arterial layers (intima, media, and adventitia) during implantation of a balloon expandable coronary stent into a stenosed artery. The atherosclerotic artery was assumed to consist of a plaque and normal/healthy arterial tissues on its outer side. The results indicated a significant influence of plaque types on the maximum stresses induced within the plaque wall and arterial layers during stenting but not when computing maximum stress on the stent. The stress on the stiffest calcified plaque wall was in the fracture level (2.38 MPa), whereas cellular and hypocellular plaques remain stable owing to less stress on their walls. Regardless of plaque types, the highest von Mises stresses were observed on the stiffest intima layer, whereas the lowest stresses were seen to be located in less stiff media layer. The computed stresses on the intima layer were found to be high enough to initiate a rupture in this stiff layer. These findings suggest a higher risk of arterial vascular injury for the intima layer, while a lower risk of arterial injury for the media and adventitia layers.

  5. Finite Element Modeling of A Novel Self-Expanding Endovascular Stent Method in Treatment of Aortic Aneurysms

    NASA Astrophysics Data System (ADS)

    Arokiaraj, Mark C.; Palacios, Igor F.

    2014-01-01

    A novel large self-expanding endovascular stent was designed with strut thickness of 70 μm × 70 μm width. The method was developed and investigated to identify a novel simpler technique in aortic aneurysm therapy. Stage 1 analysis was performed after deploying it in a virtual aneurysm model of 6 cm wide × 6 cm long fusiform hyper-elastic anisotropic design. At cell width of 9 mm, there was no buckling or migration of the stent at 180 Hg. Radial force of the stents was estimated after parametric variations. In stage 2 analysis, a prototype 300 μm × 150 μm stent with a cell width of 9 mm was chosen, and it was evaluated similarly after embedding in the aortic wall, and also with a tissue overgrowth of 1 mm over the stent. The 300/150 μm stent reduced the peak wall stress by 70% in the aneurysm and 50% reduction in compliance after embedding. Stage 3 analysis was performed to study the efficacy of stents with struts (thickness/width) 70/70, 180/100 and 300/150 μm after embedding and tissue overgrowth. The adjacent wall stresses were very minimal in stents with 180/100 and 70/70 μm struts after embedding. There is potential for a novel stent method in aortic aneurysm therapy.

  6. Intra-channel stent release technique for fluoroless endoscopic ultrasound-guided lumen-apposing metal stent placement: changing the paradigm

    PubMed Central

    Anderloni, Andrea; Attili, Fabia; Carrara, Silvia; Galasso, Domenico; Di Leo, Milena; Costamagna, Guido; Repici, Alessandro; Kunda, Rastislav; Larghi, Alberto

    2017-01-01

    Background Recently, a novel lumen-apposing fully covered self-expanding metal stent (LA-FCSEMS) mounted on an electrocautery-enhanced delivery system has been developed to perform endoscopic ultrasound (EUS)-guided transluminal drainage. From early experience, however, release of the proximal flange of the stent has mostly been done using endoscopic view guidance to ensure proper positioning. Aim We describe a new technique that we have named the Intra-Channel Stent Release Technique (ICSRT) to perform stent placement under complete EUS control, without the use of either fluoroscopic or endoscopic views. Material and methods Data on all consecutive patients who underwent EUS-guided drainage using the new ICSRT between June 2014 and April 2016 were retrospectively retrieved from two institution databases. All EUS procedures were performed by experienced endoscopists with the patient under conscious or deep sedation. The total procedure and stent deployment time, and adverse events related to stent positioning with the ICSRT were evaluated. Results One hundred consecutive patients (51 women; mean age ± SD, 66 ± 15.2 years, range 34 – 95) underwent EUS-guided transluminal drainage with the Hot AXIOS™ device using the new ICSRT. The procedure was technically successful in all but one patient (1 %). The mean total procedural time was 21.9 minutes (range 7 – 50), while the mean time for stent placement was 3.2 minutes (range 1 – 15). No major adverse events occurred. Discussion The ICSRT has been used to deploy the newly developed lumen-apposing FCSEMS under complete EUS guidance without fluoroscopic and/or endoscopic assistance. The technique appears to be safe and highly effective and should be learned by all interventional endosonographers in order to be able to perform drainage in all clinical scenarios.

  7. Stent-in-stent through a side hole to prevent biliary metallicstent migration.

    PubMed

    Ridtitid, Wiriyaporn; Rerknimitr, Rungsun; Amornsawadwattana, Surachai; Ponauthai, Yuwadee; Kullavanijaya, Pinit

    2011-03-16

    The covered self-expandable metallic stent (SEMS) has been developed to overcome the problem of tissue in-growth, However, stent migration is a well-known com--plication of covered SEMS placement. Use of a double pigtail stent to lock the movement of the SEMS and prevent migration has been advised by many ex-perts. Unfortunately, in our case this technique led to an in-cidental upward migration of the SEMS. We used APC to create a side hole in the SEMS for plastic stent insertion as stent-in-stent. This led to a successful pre-ven-tion of stent migration.

  8. Metallic stents in the management of ureteric strictures

    PubMed Central

    Kulkarni, Ravi

    2014-01-01

    Management of ureteric strictures is a challenging task. Subtle presentation, silent progression and complex aetiology may delay diagnosis. A wide range of available treatment options combined with the lack of adequate randomised trials has led to the introduction of personal bias in the management of this difficult group of patients. Metallic ureteric stents offer an alternative to the conventional treatment modalities. A review of the currently available metallic stents and their role in the long-term management of ureteric strictures is presented. Materials used in the manufacture of indwelling urological devices are evolving all the time. Improved endo-urological techniques combined with new devices made from better compounds will continue to improve patient experience. PMID:24497686

  9. Prevention of Intracranial In-stent Restenoses: Predilatation with a Drug Eluting Balloon, Followed by the Deployment of a Self-Expanding Stent

    SciTech Connect

    Vajda, Zsolt Guethe, Thomas Perez, Marta Aguilar Kurre, Wiebke; Schmid, Elisabeth Baezner, Hansjoerg; Henkes, Hans

    2013-04-15

    Stenting in intracranial atherosclerotic disease (ICAD) is increasingly debated, due to issues of procedural safety, technical efficacy, and in-stent recurrent stenoses (ISR). In the present study, feasibility, safety, and efficacy of angioplasty using a drug-eluting balloon (DEB) followed by the implantation of a self-expanding stent (Enterprise) were evaluated for the treatment of ICAD lesions. Fifty-two patients (median age: 71 years; range: 54-86 years; male/female ratio 37:15) underwent stenting of high-grade ICAD lesions between February 2010 and November 2011 in a single center. Angioplasty using a paclitaxel coated SeQuent Please (B. Braun, Germany) or DIOR (Eurocor, Germany) coronary PTCA balloon, followed by the implantation of a self-expanding stent (Enterprise, Codman, USA) was performed in 54 lesions. Angiographic and clinical follow-up was performed at 6 and 12 weeks, 6 and 12 months, and yearly thereafter. Technical success rate, periprocedural complications, occurrence of recurrent ischemic symptoms, and the development of an ISR were analyzed. Angioplasty using a DEB followed by stent implantation was successfully performed in 44 (81 %) cases. DEB insertion failed in 19 % of the cases and angioplasty was finally performed using a conventional PTCA balloon. The combined procedure related permanent neurologic morbidity and mortality rate (stroke, ICH, and subarachnoid hemorrhage) at 30 days and beyond was 5 %. Angiographic and clinical follow-up were obtained in 33 (61 %) lesions in 32 patients. Recurrent stenosis was seen in one (3 %) lesion. Angioplasty and stenting using a DEB is safe and yields encouragingly low ISR rates. Further technical developments to improve lesion accessibility are, nevertheless, mandatory.

  10. Biodegradable shape-memory block co-polymers for fast self-expandable stents.

    PubMed

    Xue, Liang; Dai, Shiyao; Li, Zhi

    2010-11-01

    Block co-polymers PCTBVs (M(n) of 36,300-65,300 g/mol, T(m) of 39-40 and 142 degrees C) containing hyperbranched three-arm poly(epsilon-caprolactone) (PCL) as switching segment and microbial polyester PHBV as crystallizable hard segment were designed as biodegradable shape-memory polymer (SMP) for fast self-expandable stent and synthesized in 96% yield by the reaction of three-arm PCL-triol (M(n) of 4200 g/mol, T(m) of 47 degrees C) with methylene diphenyl 4,4'-diisocyanate isocynate (MDI) to form the hyperbrached MDI-linked PCL (PTCM; M(n) of 25,400 g/mol and a T(m) of 38 degrees C), followed by further polymerization with PHBV-diol (M(n) of 2200 g/mol, T(m) of 137 and 148 degrees C). The polymers were characterized by (1)H NMR, GPC, DSC, tensile test, and cyclic thermomechanical tensile test. PCTBVs showed desired thermal properties, mechanical properties, and ductile nature. PCTBV containing 25 wt% PHBV (PCTBV-25) demonstrated excellent shape-memory property at 40 degrees C, with R(f) of 94%, R(r) of 98%, and shape recovery within 25s. PCTBV-25 was also shown as a safe material with good biocompatibility by cytotoxicity tests and cell growth experiments. The stent made from PCTBV-25 film showed nearly complete self-expansion at 37 degrees C within only 25 s, which is much better and faster than the best known self-expandable stents.

  11. Malignant tracheal-mediastinal-parenchymal-pleural fistula after chemoradiation plus bevacizumab: management with a Y-silicone stent inside a metallic covered stent.

    PubMed

    Machuzak, Michael S; Santacruz, Jose F; Jaber, Wissam; Gildea, Thomas R

    2015-01-01

    Tracheal or bronchial-mediastinal fistulas are a rare entity associated to high mortality. We report a case of a 58-year-old man with an unresectable non-small cell carcinoma of the lung, treated with chemoradiation followed by bevacizumab. Approximately, 6 weeks after starting bevacizumab he developed a severe cough with copious secretions He could not lie supine due to the feeling of drowning. Investigations revealed a large tracheo-mediastinal-parenchymal-pleural fistula. Palliative management was offered with interventional bronchoscopic techniques. He was found to have a large central airway defect that obliterated almost 40% of the trachea. Under general anesthesia and positive pressure ventilation, a unique approach was used to rebuild an eroded tracheal and right main stem bronchial wall. A self-expanding metallic stent (SEMS) was placed to provide a scaffold of support, whereas a Dumon Y-stent was placed inside the SEMS. This combination allowed for a patent, stable airway; recreating the normal anatomy in a minimally invasive manner walling off the fistula. The patient was discharged 2 days after the bronchoscopic intervention, with significant palliation of his symptomatology. Eighteen months later, the upper lobe cavity persists with a stable airway and stents perfectly positioned with clinically insignificant evidence of stent related granulation in the upper trachea.

  12. Transition Metal Complexes of Expanded Porphyrins

    PubMed Central

    Sessler, Jonathan L.; Tomat, Elisa

    2008-01-01

    Over the last two decades, the rapid development of new synthetic routes for the preparation of expanded porphyrin macrocycles has allowed exploration of a new frontier consisting of “porphyrin-like” coordination chemistry. In this Account, we summarize our exploratory forays into the still relatively poorly explored area of oligopyrrolic macrocycle metalation chemistry. Specifically, we describe our successful formation of both mono- and binuclear complexes and in doing so highlight the diversity of coordination modes available to expanded porphyrin-type ligands. The nature of the inserted cation, the emerging role of tautomeric equilibria, and the importance of hydrogen-bonding interactions in regulating this chemistry are also discussed. PMID:17397134

  13. A physical corrosion model for bioabsorbable metal stents.

    PubMed

    Grogan, J A; Leen, S B; McHugh, P E

    2014-05-01

    Absorbable metal stents (AMSs) are an emerging technology in the treatment of heart disease. Computational modelling of AMS performance will facilitate the development of this technology. In this study a physical corrosion model is developed for AMSs based on the finite element method and adaptive meshing. The model addresses a gap between currently available phenomenological corrosion models for AMSs and physical corrosion models that have been developed for more simple geometries than those of a stent. The model developed in this study captures the changing surface of a corroding three-dimensional AMS structure for the case of diffusion-controlled corrosion. Comparisons are made between model predictions and those of previously developed phenomenological corrosion models for AMSs in terms of predicted device geometry and mechanical performance during corrosion. Relationships between alloy solubility and diffusivity in the corrosion environment and device performance during corrosion are also investigated.

  14. Study of the Behavior of a Bell-Shaped Colonic Self-Expandable NiTi Stent under Peristaltic Movements

    PubMed Central

    Puértolas, José A.; López, Enrique

    2013-01-01

    Managing bowel obstruction produced by colon cancer requires an emergency intervention to patients usually in poor conditions, and it requires creating an intestinal stoma in most cases. Regardless of that the tumor may be resectable, a two-stage surgery is mandatory. To avoid these disadvantages, endoscopic placement of self-expanding stents has been introduced more than 10 years ago, as an alternative to relieve colonic obstruction. It can be used as a bridge to elective single-stage surgery avoiding a stoma or as a definitive palliative solution in patients with irresectable tumor or poor estimated survival. Stents must be capable of exerting an adequate radial pressure on the stenosed wall, keeping in mind that stent must not move or be crushed, guaranteeing an adequate lumen when affected by peristaltic waves. A finite element simulation of bell-shaped nitinol stent functionality has been done. Catheter introduction, releasing at position, and the effect of peristaltic wave were simulated. To check the reliability of the simulation, a clinical experimentation with porcine specimens was carried out. The stent presented a good deployment and flexibility. Stent behavior was excellent, expanding from the very narrow lumen corresponding to the maximum peristaltic pressure to the complete recovery of operative lumen when the pressure disappears. PMID:23841067

  15. A Computational Framework to Model Degradation of Biocorrodible Metal Stents Using an Implicit Finite Element Solver.

    PubMed

    Debusschere, Nic; Segers, Patrick; Dubruel, Peter; Verhegghe, Benedict; De Beule, Matthieu

    2016-02-01

    Bioresorbable stents represent an emerging technological development within the field of cardiovascular angioplasty. Their temporary presence avoids long-term side effects of non-degradable stents such as in-stent restenosis, late stent thrombosis and fatigue induced strut fracture. Several numerical modelling strategies have been proposed to evaluate the transitional mechanical characteristics of biodegradable stents using a continuum damage framework. However, these methods rely on an explicit finite-element integration scheme which, in combination with the quasi-static nature of many simulations involving stents and the small element size needed to model corrosion mechanisms, results in a high computational cost. To reduce the simulation times and to expand the general applicability of these degradation models, this paper investigates an implicit finite element solution method to model degradation of biodegradable stents.

  16. Biodegradable Metals for Cardiovascular Stents: from Clinical Concerns to Recent Zn-Alloys.

    PubMed

    Bowen, Patrick K; Shearier, Emily R; Zhao, Shan; Guillory, Roger J; Zhao, Feng; Goldman, Jeremy; Drelich, Jaroslaw W

    2016-05-01

    Metallic stents are used to promote revascularization and maintain patency of plaqued or damaged arteries following balloon angioplasty. To mitigate the long-term side effects associated with corrosion-resistant stents (i.e., chronic inflammation and late stage thrombosis), a new generation of so-called "bioabsorbable" stents is currently being developed. The bioabsorbable coronary stents will corrode and be absorbed by the artery after completing their task as vascular scaffolding. Research spanning the last two decades has focused on biodegradable polymeric, iron-based, and magnesium-based stent materials. The inherent mechanical and surface properties of metals make them more attractive stent material candidates than their polymeric counterparts. A third class of metallic bioabsorbable materials that are based on zinc has been introduced in the last few years. This new zinc-based class of materials demonstrates the potential for an absorbable metallic stent with the mechanical and biodegradation characteristics required for optimal stent performance. This review compares bioabsorbable materials and summarizes progress towards bioabsorbable stents. It emphasizes the current understanding of physiological and biological benefits of zinc and its biocompatibility. Finally, the review provides an outlook on challenges in designing zinc-based stents of optimal mechanical properties and biodegradation rate.

  17. Upper Gastrointestinal Stent Insertion in Malignant and Benign Disorders

    PubMed Central

    Kang, Hyoun Woo

    2015-01-01

    Upper gastrointestinal (GI) stents are increasingly being used to manage upper GI obstructions. Initially developed for palliative treatment of esophageal cancer, upper GI stents now play an emerging role in benign strictures of the upper GI tract. Because recurrent obstruction and stent-related complications are common, new modifications of stents have been implemented. Self-expandable metal stents (SEMS) have replaced older plastic stents. In addition, newly designed SEMS have been developed to prevent complications. This review provides an overview of the various types, indications, methods, complications, and clinical outcomes of upper GI stents in a number of malignant and benign disorders dividing the esophagus and gastroduodenum. PMID:26064817

  18. Role of Stent Grafts and Helical-Woven Bare-Metal Stents in the Superficial Femoral and Popliteal Arteries.

    PubMed

    Madassery, Sreekumar; Turba, Ulku C; Arslan, Bulent

    2016-06-01

    Peripheral vascular disease (PVD) is a devastating medical problem that may lead to significant life alterations for patients, from simply limiting their daily activities to potential loss of limbs and eventual demise. Superficial femoral and popliteal arteries are significantly common locations for PVD sequelae to present itself, and owing to their length and mobile nature, treatment of these segments are quite challenging. Indications for PVD treatment include lifestyle-limiting claudication that is not responding to medical management, ischemic rest pain, nonhealing ulcers, and lower extremity gangrene. There is a wide variety of treatment options that include medical management, interventional, and surgical techniques. Interventional techniques include plain old balloon angioplasty, cryoplasty, drug-coated balloon angioplasty, self-expanding bare-nitinol stents, self-expanding covered stents, self-expanding drug-eluding stents, and a number of atherectomy devices (ie, laser, rotational, orbital, and excisional). The scope of this article is to review indications, patient selection, and deployment techniques of Viabahn and Supera self-expanding stents.

  19. Bronchobiliary Fistula Treated by Self-expanding ePTFE-Covered Nitinol Stent-Graft

    SciTech Connect

    Gandini, Roberto; Konda, Daniel Tisone, Giuseppe; Pipitone, Vincenzo; Anselmo, Alessandro; Simonetti, Giovanni

    2005-12-15

    A 71-year-old man, who had undergone right hepatectomy extended to the caudate lobe with terminolateral Roux-en-Y left hepatojejunostomy for a Klatskin tumor, developed bilioptysis 3 weeks postoperatively due to bronchobiliary fistula. Percutaneous transhepatic cholangiography revealed a non-dilated biliary system with contrast medium extravasation to the right subphrenic space through a resected anomalous right posterior segmental duct. After initial unsuccessful internal-external biliary drainage, the fistula was sealed with a VIATORR covered self-expanding nitinol stent-graft placed with its distal uncovered region in the hepatojejunal anastomosis and the proximal ePTFE-lined region in the left hepatic duct. A 10-month follow-up revealed no recurrence of bilioptysis and confirmed the complete exclusion of the bronchobiliary fistula.

  20. Efficacy of Retrievable Metallic Stent with Fixation String for Benign Stricture after Upper Gastrointestinal Surgery

    PubMed Central

    Kim, Jeong-Eun; Lee, Myungsu; Hur, Saebeom; Kim, Minuk; Lee, Sang Hwan; Cho, Soo Buem; Kim, Chan Sun; Han, Joon Koo

    2016-01-01

    Objective To determine the efficacy of retrievable metallic stent with fixation string for benign anastomotic stricture after upper gastrointestinal (UGI) surgery. Materials and Methods From June 2009 to May 2015, a total of 56 retrievable metallic stents with fixation string were placed under fluoroscopy guidance in 42 patients who were diagnosed with benign anastomotic stricture after UGI surgery. Clinical success was defined as achieving normal regular diet (NRD). Results The clinical success rate after the first stent placement was 57.1% (24/42). After repeated stent placement and/or balloon dilation, the clinical success rate was increased to 83.3% (35/42). Six (14.3%) patients required surgical revision to achieve NRD. One (2.4%) patient failed to achieve NRD. Stent migration occurred in 60.7% (34/56) of patients. Successful rate of removing the stent using fixation string and angiocatheter was 94.6% (53/56). Distal migration occurred in 12 stents. Of the 12 stents, 10 (83.3%) were successfully removed whereas 2 could not be removed. No complication occurred regarding distal migration. Conclusion Using retrievable metallic stent with a fixation string is a feasible option for managing early benign anastomotic stricture after UGI surgery. It can reduce complications caused by distal migration of the stent. PMID:27833405

  1. Y-configured metallic stent combined with 125I seed strands cavity brachytherapy for a patient with type IV Klatskin tumor

    PubMed Central

    Dechao, Jiao; Yanli, Wang; Zhen, Li

    2016-01-01

    We report a case in an inoperable patient with type IV Klatskin tumor treated by the use of a novel, two piece, Y-configured self-expandable metallic stent (SEMS) combined with two 125I seed strands via bilateral approach. The placement of the Y-shaped SEMS was successful and resulted in adequate biliary drainage. After 2 months of intraluminal brachytherapy (ILBT), both 125I seed strands and temporary drainage catheter were removed after patency of the expanded stents was confirmed by the cholangiogram. This technique was feasible and could be considered for the treatment of patients with Bismuth type IV Klatskin tumors. PMID:27648091

  2. Outcomes of Prosthetic Hemodialysis Grafts after Deployment of Bare Metal versus Covered Stents at the Venous Anastomosis

    SciTech Connect

    Kim, Charles Y. Tandberg, Daniel J.; Rosenberg, Michael D.; Miller, Michael J.; Suhocki, Paul V.; Smith, Tony P.

    2012-08-15

    Purpose: To compare postintervention patency rates after deployment of bare metal versus covered stents across the venous anastomosis of prosthetic arteriovenous (AV) grafts. Methods: Review of our procedural database over a 6 year period revealed 377 procedures involving stent deployment in an AV access circuit. After applying strict inclusion criteria, our study group consisted of 61 stent deployments in 58 patients (median age 58 years, 25 men, 33 women) across the venous anastomosis of an upper extremity AV graft circuit that had never been previously stented. Both patent and thrombosed AV access circuits were retrospectively analyzed. Within the bare metal stent group, 20 of 32 AV grafts were thrombosed at initial presentation compared to 18 of 29 AV grafts in the covered stent group. Results: Thirty-two bare metal stents and 29 covered stents were deployed across the venous anastomosis. The 3, 6, and 12 months primary access patency rates for bare metal stents were not significantly different than for covered stents: 50, 41, and 22 % compared to 59, 52, and 29 %, respectively (p = 0.21). The secondary patency rates were also not significantly different: 78, 78, and 68 % for bare metal stents compared to 76, 69, and 61 % for covered stents, respectively (p = 0.85). However, covered stents demonstrated a higher primary stent patency rate than bare metal stents: 100, 85, and 70 % compared to 75, 67, and 49 % at 3, 6, and 12 months (p < 0.01). Conclusion: The primary and secondary access patency rates after deployment of bare metal versus covered stents at the venous anastomosis were not significantly different. However, bare metal stents developed in-stent stenoses significantly sooner.

  3. Endovascular Repair of Arterial Iliac Vessel Wall Lesions with a Self-Expandable Nitinol Stent Graft System

    PubMed Central

    Mensel, Birger; Kühn, Jens-Peter; Hoene, Andreas; Hosten, Norbert; Puls, Ralf

    2014-01-01

    Objective To assess the therapeutic outcome after endovascular repair of iliac arterial lesions (IALs) using a self-expandable Nitinol stent graft system. Methods Between July 2006 and March 2013, 16 patients (13 males, mean age: 68 years) with a self-expandable Nitinol stent graft. A total of 19 lesions were treated: nine true aneurysms, two anastomotic aneurysms, two dissections, one arteriovenous fistula, two type 1B endoleaks after endovascular aneurysm repair, one pseudoaneurysm, and two perforations after angioplasty. Pre-, intra-, and postinterventional imaging studies and the medical records were analyzed for technical and clinical success and postinterventional complications. Results The primary technical and clinical success rate was 81.3% (13/16 patients) and 75.0% (12/16), respectively. Two patients had technical failure due to persistent type 1A endoleak and another patient due to acute stent graft thrombosis. One patient showed severe stent graft kinking on the first postinterventional day. In two patients, a second intervention was performed. The secondary technical and clinical success rate was 87.5% (14/16) and 93.8% (15/16). The minor complication rate was 6.3% (patient with painful hematoma at the access site). The major complication rate was 6.3% (patient with ipsilateral deep vein thrombosis). During median follow-up of 22.4 months, an infection of the aneurysm sac in one patient and a stent graft thrombosis in another patient were observed. Conclusion Endovascular repair of various IALs with a self-expandable Nitinol stent graft is safe and effective. PMID:25119346

  4. Expandable Metal Liner For Downhole Components

    DOEpatents

    Hall, David R.; Fox, Joe R.

    2004-10-05

    A liner for an annular downhole component is comprised of an expandable metal tube having indentations along its surface. The indentations are formed in the wall of the tube either by drawing the tube through a die, by hydroforming, by stamping, or roll forming and may extend axially, radially, or spirally along its wall. The indentations accommodate radial and axial expansion of the tube within the downhole component. The tube is inserted into the annular component and deformed to match an inside surface of the component. The tube may be expanded using a hydroforming process or by drawing a mandrel through the tube. The tube may be expanded in such a manner so as to place it in compression against the inside wall of the component. The tube is useful for improving component hydraulics, shielding components from contamination, inhibiting corrosion, and preventing wear to the downhole component during use. It may also be useful for positioning conduit and insulated conductors within the component. An insulating material may be disposed between the tube and the component in order to prevent galvanic corrosion of the downhole component.

  5. Use of expanded polytetrafluoroethylen (ePTFE) stent graft in autogenic AV fistula with false aneurysm in lower extremity.

    PubMed

    Sieroń, Dominik; Wiggermann, Philipp; Knap, Daniel; Wawrzynek, Wojciech; Stroszczynski, Christian

    2012-04-01

    A 28-year-old German-Caucasian man arrived with deep vein thrombosis DVT, pain, oedema and rubor of right lower limb and drug abuse. The US Doppler imaging showed an autogenic AV fistula and false aneurysm of the right superficial femoral artery and femoral vein. The CT imaging showed additional closing of the left external iliac artery and common femoral artery, and of the distal and middle parts of the superficial femoral artery. The patient was treated within the angiography suite using a 8/25 mm (8 mm diameter/25 mm length) peripheral graft with expanded polytetrafluoroethylen ePTFE stent. After stent deployment, the dilatation was performed using 8/20 mm (8 mm diameter/20 mm length) balloons. After intervention, the digital subtraction angiography showed a good stent position with complete exclusion of false aneurysm and AV fistula. The outcome of US Doppler imaging also confirmed successful intervention.

  6. Very Late Stent Thrombosis After Primary Percutaneous Coronary Intervention With Bare-Metal and Drug-Eluting Stents for ST-Segment Elevation Myocardial Infarction

    PubMed Central

    Brodie, Bruce; Pokharel, Yashashwi; Fleishman, Nathan; Bensimhon, Adam; Kissling, Grace; Hansen, Charles; Milks, Sally; Cooper, Michael; McAlhany, Christopher; Stuckey, Tom

    2011-01-01

    Objectives The purpose of this study was to assess the frequency of very late stent thrombosis (VLST) after stenting with bare-metal stents (BMS) and drug-eluting stents (DES) for ST-segment elevation myocardial infarction (STEMI). Background Stent thrombosis occurs more frequently after stenting for STEMI than after elective stenting, but there are little data regarding VLST. Methods Consecutive patients (n = 1,463) who underwent stenting for STEMI were prospectively enrolled in our database. BMS were implanted exclusively from 1995 to 2002, and DES and BMS were implanted from 2003 to 2009. Follow-up was obtained at 1 to 15 years. Results Bare-metal stent patients (n = 1,095) were older and had more shock, whereas DES patients (n = 368) had more diabetes and smaller vessels. Stent thrombosis occurred in 107 patients, of which 42 were VLST (>1 year). Stent thrombosis continued to increase to at least 11 years with BMS and to at least 4.5 years with DES. Stent thrombosis rates with BMS versus DES were similar at 1 year (5.1% and 4.0%, respectively) but increased more with DES after the first year (1.9%/year vs. 0.6%/year, respectively). Landmark analysis (>1 year) found DES had a higher frequency of VLST (p < 0.001) and reinfarction (p = 0.003). Drug-eluting stent was the only significant independent predictor of VLST (hazard ratio: 3.79, 95% confidence interval: 1.64 to 8.79, p = 0.002). Conclusions Very late stent thrombosis after primary PCI for STEMI occurs with relatively high frequency to at least 11 years with BMS and to at least 4.5 years with DES. Very late stent thrombosis and reinfarction (>1 year) were more frequent with DES. New strategies are needed to manage this problem. PMID:21251626

  7. Endoscopic ultrasound-guided gastrojejunostomy with a lumen-apposing metal stent: a multicenter, international experience

    PubMed Central

    Tyberg, Amy; Perez-Miranda, Manuel; Sanchez-Ocaña, Ramon; Peñas, Irene; de la Serna, Carlos; Shah, Janak; Binmoeller, Kenneth; Gaidhane, Monica; Grimm, Ian; Baron, Todd; Kahaleh, Michel

    2016-01-01

    Background: Surgical gastrojejunostomy and enteral self-expanding metal stents are efficacious for the management of gastric outlet obstruction but limited by high complication rates and short-term efficacy. Endoscopic ultrasound-guided gastrojejunostomy (EUS-GJ) is a novel alternative option. Patients and methods: Patients who underwent EUS-GJ between March 2014 and September 2015 as part of a prospective multicenter registry at four academic centers in two countries were included. Technical success was defined as successful placement of a gastrojejunal lumen-apposing metal stent. Clinical success was defined as the ability of the patient to tolerate an oral diet. Post-procedural adverse events were recorded. Results: The study included 26 patients, of whom 11 (42 %) were male. Technical success was achieved in 24 patients (92 %). Clinical success was achieved in 22 patients (85 %). Of the 4 patients in whom clinical success was not achieved, 2 had persistent nausea and vomiting despite a patent EUS-GJ and required enteral feeding for nutrition, 1 died before the initiation of an oral diet, and 1 underwent surgery for suspected perforation. Adverse events, including peritonitis, bleeding, and surgery, occurred in 3 patients (11.5 %). Conclusion: EUS-GJ is an emerging procedure that has efficacy and safety comparable with those of current therapies and should hold a place as a new minimally invasive option for patients with gastric outlet obstruction. Clinical trial identification number: NCT01522573 PMID:27004243

  8. The first use of Resonance® metallic ureteric stent in a case of obstructed transplant kidney

    PubMed Central

    Abdulmajed, Mohamed I.; Jones, Vaughan W.; Shergill, Iqbal S.

    2014-01-01

    INTRODUCTION To date, double JJ stent is the mainstay ureteric stent used in a transplant kidney. We herein report the first use of Resonance® metallic ureteric stent to manage ureteric obstruction in a transplant kidney. PRESENTATION OF CASE A 45-year-old lady underwent an uneventful living related donor renal transplantation. Due to post-operative pelvi-ureteric obstruction and recurrent obstruction following multiple distal stent migration and expulsion necessitated frequent nephrostomy insertion and antegrade stenting, she underwent challenging but successful retrograde insertion of a 12 centimetres long and size 6.0 French Cook Resonance® metallic ureteric stent which was performed under general anaesthesia. DISCUSSION Metallic ureteric stents are a fairly recent introduction to modern urology and they have been successfully used in the management of benign and malignant obstruction of ureter. CONCLUSION This is the first case of therapeutic metallic ureteric stent insertion in a transplant kidney. PMID:24858983

  9. Atherosclerotic plaque behind the stent changes after bare-metal and drug-eluting stent implantation in humans: implications for late stent failure?

    PubMed Central

    Andreou, Ioannis; Takahashi, Saeko; Tsuda, Masaya; Shishido, Koki; Antoniadis, Antonios P.; Papafaklis, Michail I.; Mizuno, Shingo; Coskun, Ahmet U.; Saito, Shigeru; Feldman, Charles L.; Edelman, Elazer R.; Stone, Peter H.

    2016-01-01

    Background and aims The natural history and the role of atherosclerotic plaque located behind the stent (PBS) are still poorly understood. We evaluated the serial changes in PBS following bare-metal (BMS) compared to first-generation drug-eluting stent (DES) implantation and the impact of these changes on in-stent neointimal hyperplasia (NIH). Methods Three-dimensional coronary reconstruction by angiography and intravascular ultrasound was performed after intervention and at 6–10-month follow-up in 157 patients with 188 lesions treated with BMS (n=89) and DES (n=99). Results There was a significant decrease in PBS area (−7.2%; p<0.001) and vessel area (−1.7%; p<0.001) after BMS and a respective increase in both areas after DES implantation (6.1%; p<0.001 and 4.1%; p<0.001, respectively). The decrease in PBS area significantly predicted neointimal area at follow-up after BMS (β: 0.15; 95% confidence interval [CI]: 0.10–0.20, p<0.001) and DES (β: 0.09; 95% CI: 0.07–0.11; p<0.001) implantation. The decrease in PBS area was the most powerful predictor of significant NIH after BMS implantation (odds ratio: 1.13; 95% CI: 1.02–1.26; p=0.02). Conclusions The decrease in PBS area after stent implantation is significantly associated with the magnitude of NIH development at follow-up. This finding raises the possibility of a communication between the lesion within the stent and the underlying native atherosclerotic plaque, and may have important implications regarding the pathobiology of in-stent restenosis and late/very late stent thrombosis. PMID:27494445

  10. Combined Arterial Infusion and Stent Implantation Compared with Metal Stent Alone in Treatment of Malignant Gastroduodenal Obstruction

    SciTech Connect

    Wang Zhongmin; Chen Kemin; Gong Ju; Zheng Yunfeng; Wang Tianxiang

    2009-09-15

    Many patients with malignant gastroduodenal obstruction have an unresectable primary lesion and distant metastases, which may prompt palliative management to allow the patient to eat and to improve the quality of life. Intraluminal metallic stent implantation (MSI) under fluoroscopic guidance has been reported to be an effective option for symptomatic relief in these patients, with a good safety record. An alternative, dual interventional therapy (DIT), has been used during the last decade, in which prosthesis insertion is followed by intra-arterial chemotherapy via the tumor-feeding arteries. The aim of this study was to compare success rates, complication rates, and survival time between MSI and DIT in patients who presented with gastroduodenal obstruction from advanced upper gastrointestinal tract cancer. All consecutive patients with malignant gastroduodenal obstruction seen at our center between October 2002 and August 2007 were retrospectively studied. Patients were treated palliatively by either MSI or DIT by the patient's or the next of kin's decision. Outcomes included technical and clinical success, complication rates, and survival. Of the 164 patients with malignant gastric and duodenal outlet obstructions, 80 (49%) underwent stent insertion as the primary therapy, while the remaining 84 (51%) received DIT. Clinical characteristics were similar between the two groups. In the MSI cohort initial stent implantation was successful in 73 patients (91%), two stents were used in 5 patients, and delayed additional stent insertion for stent obstruction related to tumor overgrowth was required in 3 patients during follow-up. In the DIT cohort the technical success rate was 94%, 3 patients required two stents, and stent obstruction occurred in 2 patients after initial stent placement. Early postprocedural clinical success, indicated by average dysphagia score, improved significantly in both groups: MSI group, from 4.56 to 1.51 (P < 0.01); and DIT group, from 4

  11. Are “Treatment” Bare Metal Stents Superior to “Control” Bare Metal Stents? A meta-analytic approach

    PubMed Central

    Kent, David M; Trikalinos, Thomas A

    2011-01-01

    Background It has been suggested that the benefits of drug-eluting stents compared to bare metal stents (BMS) have been over-estimated in part because target lesion/vessel revascularization (TLR/TVR) rates in the BMS control group of these trials were spuriously high. Methods We used meta-analytic techniques to systematically compare clinical event rates among patients treated with BMS in trials where BMS were the experimental (BMSexperimental) rather than the control (BMScontrol) intervention. MEDLINE searches were performed to identify eligible randomized trials comparing either drug-eluting stents with BMScontrol, or BMSexperimental with balloon angioplasty in patients with non-acute coronary artery disease. Trial characteristics and 6 to 12 month rates for death, myocardial infarction, TLR/TVR and major adverse cardiac events (MACE) were extracted and assessed. Results Eligible trials yielded 50 BMS cohorts: 19 in the BMScontrol group (4 046 patients) and 31 in the BMSexperimental group (5 068 patients). Summary death and infarction rates did not differ between groups. The summary TLR/TVR rates were 16.2% (95% confidence interval, CI: 13.5, 19.3) versus 13.8% (95% CI: 12.0, 15.7) in BMScontrol versus BMSexperimental groups, respectively (p=0.15). Among 39 BMS cohorts with ≤250 patients, TLR/TVR rates were significantly higher in BMScontrol versus BMSexperimental groups (18.9% [95% CI: 16.0, 22.2] versus 13.7% [95% CI: 11.5, 16.3], p=0.01). There were no between-group differences among larger BMS cohorts (p=0.98). Conclusions While overall clinical event rates did not differ in the BMScontrol and the BMSexperimental groups, a higher rate of TVR/TLR was seen in the BMScontrol group among smaller trials. PMID:18371468

  12. Stent-Assisted Coil Embolization of a Mycotic Renal Artery Aneurysm by Use of a Self-Expanding Neurointerventional Stent

    SciTech Connect

    Rabellino, Martin; Garcia-Nielsen, Luis; Zander, Tobias Baldi, Sebastian; Llorens, Rafael; Maynar, Manuel

    2011-02-15

    Mycotic aneurysms are uncommon, especially those located in visceral arteries. We present a case of a patient with two visceral mycotic aneurysms due to bacterial endocarditis, one located in right upper pole renal artery and the second in the splenic artery. Both aneurysms were treated as endovascular embolization using microcoils. In the aneurysm located at the renal artery, the technique of stent-assisted coils embolization was preferred to avoid coils migration due to its wide neck. The stent used was the Solitaire AB, which was designed for the treatment of intracranial aneurysms and was used recently in acute stroke as a mechanical thrombectomy device. Complete embolization of the aneurysm was achieved, preserving all the arterial branches without nephrogram defects in the final angiogram.

  13. Ferromagnetic Bare Metal Stent for Endothelial Cell Capture and Retention

    PubMed Central

    Uthamaraj, Susheil; Tefft, Brandon J.; Hlinomaz, Ota; Sandhu, Gurpreet S.; Dragomir-Daescu, Dan

    2015-01-01

    Rapid endothelialization of cardiovascular stents is needed to reduce stent thrombosis and to avoid anti-platelet therapy which can reduce bleeding risk. The feasibility of using magnetic forces to capture and retain endothelial outgrowth cells (EOC) labeled with super paramagnetic iron oxide nanoparticles (SPION) has been shown previously. But this technique requires the development of a mechanically functional stent from a magnetic and biocompatible material followed by in-vitro and in-vivo testing to prove rapid endothelialization. We developed a weakly ferromagnetic stent from 2205 duplex stainless steel using computer aided design (CAD) and its design was further refined using finite element analysis (FEA). The final design of the stent exhibited a principal strain below the fracture limit of the material during mechanical crimping and expansion. One hundred stents were manufactured and a subset of them was used for mechanical testing, retained magnetic field measurements, in-vitro cell capture studies, and in-vivo implantation studies. Ten stents were tested for deployment to verify if they sustained crimping and expansion cycle without failure. Another 10 stents were magnetized using a strong neodymium magnet and their retained magnetic field was measured. The stents showed that the retained magnetism was sufficient to capture SPION-labeled EOC in our in-vitro studies. SPION-labeled EOC capture and retention was verified in large animal models by implanting 1 magnetized stent and 1 non-magnetized control stent in each of 4 pigs. The stented arteries were explanted after 7 days and analyzed histologically. The weakly magnetic stents developed in this study were capable of attracting and retaining SPION-labeled endothelial cells which can promote rapid healing. PMID:26436434

  14. Corrosion Behavior of Platinum-Enhanced Radiopaque Stainless Steel (PERSS®) for Dilation-Baloon Expandable Coronary Stents

    SciTech Connect

    Covino, Jr., Bernard S.; Craig, Charles H.; Cramer, Stephen D.; Bullard, Sophie J.; Ziomek-Moroz, Margaret; Jablonski, Paul D.; Turner, Paul C.; Radisch, Jr., Herbert R.; Gokcen, Nev A.; Friend, Clifford M.; Edwards, Michael R.

    2002-05-01

    Dilation-balloon expandable coronary stents are commonly made of implant grade stainless steels conforming to ASTM F138/F139, e.g., Biodur? 316LS (UNS S31673). Typical of such stents is the Boston Scientific/Interventional Technologies? (BS/IVT) LP-StentTM. In 2000, BS/IVT determined that the addition of 5 to 6 wt % platinum to Biodur 316LS produced a stainless steel with enhanced radiopacity to make their stents more visible radiographically and thus more effective clinically. A goal of the program was to ensure platinum additions would not adversely affect the corrosion resistance of Biodur 316LS. The corrosion resistance of 5-6 wt % PERSS? alloys and Biodur 316LS was determined using electrochemical tests for general, pitting, crevice and intergranular corrosion. Experimental methods included ASTM A262E, F746, F2129, and potentiodynamic polarization. The 6 wt % PERSS? alloy (IVT 78) had a resistance to pitting, crevice and intergranular corrosion that was similar to the Biodur 316LS base material. IVT 78 was a single-phase austenitic alloy with no evidence of inclusions or precipitates. It was more resistant to pitting corrosion than 5 wt % PERSS? alloys. Performance of the PERSS? alloys was not a function of alloy oxygen content in the range 0.01 to 0.03 wt %.

  15. Clinical remission following endoscopic placement of retrievable, fully covered metal stents in patients with esophageal achalasia.

    PubMed

    Zeng, Y; Dai, Y-M; Wan, X-J

    2014-01-01

    Metal stents may represent an alternative therapy in the treatment of achalasia. We therefore evaluated the effectiveness of retrievable, fully covered metal stents in patients with achalasia. Fifty-nine patients with achalasia were treated with retrievable, fully covered metal stents. Symptoms using a global symptom score (0-10), lower esophageal sphincter (LES) resting pressure, LES relaxation, and simultaneous contraction of the esophagus were analyzed before and 1 week and 1 month after intervention. Complications and treatment outcomes were followed up at 6, 12, 18, and 24 months postoperatively. Stent placement was successful, and clinical symptoms resolved (P < 0.01) in all patients. Regurgitation, dysphagia and chest pain improved significantly (all P < 0.01). Therapy improved LES resting pressure (51.4 ± 9.7 mmHg pretherapy vs. 20.9 ± 8.1 mmHg post-therapy), LES relaxation (58.1 ± 17.1% pretherapy vs. 84.5 ± 18.9% post-therapy), and simultaneous contraction of the esophagus (36.1 ± 8.6% pretherapy vs. 69.4 ± 23.1% post-therapy) 1 month after stent placement (all P < 0.01). The cumulative clinical remission rates 6, 12, 18, 24, 30, and 36 months after stent removal were 90.9%, 81.8%, 76.4%, 69.1%, 65.5%, and 49.1%, respectively. All patients tolerated stent placement. Twelve patients (25.5%) complained of substernal pain and five (10.6%) had substernal burning. Stents migrated in four patients (8.5%). Insertion of retrievable, fully covered metal stents is an effective and safe treatment in patients with achalasia.

  16. Implantability, Complications, and Follow-Up After Transjugular Intrahepatic Portosystemic Stent-Shunt Creation With the 6F Self-Expanding Sinus-SuperFlex-Visual Stent

    PubMed Central

    Spira, Daniel; Wiskirchen, Jakub; Lauer, Ulrich; Ketelsen, Dominik; Nikolaou, Konstantin; Wiesinger, Benjamin

    2016-01-01

    Background The transjugular intrahepatic portosystemic stent-shunt (TIPSS) builds a shortcut between the portal vein and a liver vein, and represents a sophisticated alternative to open surgery in the management of portal hypertension or its complications. Objectives To describe clinical experiences with a low-profile nitinol stent system in TIPSS creation, and to assess primary and long-term success. Patients and Methods Twenty-six patients (5 females, 21 males; mean age 54.6 years) were treated using a low-profile 6F self-expanding sinus-SuperFlex-Visual stent system. The indication for TIPSS creation was refractory bleeding in 9 of the 26 patients, refractory ascites in 18 patients, and acute thrombosis of the portal vein confluence in one patient. Portosystemic pressure gradients before and after TIPSS, periprocedural and long-term complications, and the time to orthotopic liver transplantation (OLT) or death were recorded. Results The portosystemic pressure gradient was significantly reduced, from 20.9 ± 6.3 mmHg before to 8.2 ± 2.3 mmHg after TIPSS creation (P < 0.001). Procedure-related complications included acute tract occlusion (n = 2), liver hematoma (n = 1), hepatic encephalopathy (n = 1), and cardiac failure (n = 1). Three of the 26 patients had late-onset TIPSS occlusion (at 12, 12, and 39 months after TIPSS creation). Three patients died within one week after the procedure due to their poor general condition (multiorgan failure, acute respiratory distress syndrome, necrotizing pancreatitis, and aspiration pneumonia). Another four patients succumbed to their underlying advanced liver disease within one year after TIPSS insertion. Seven patients underwent OLT at a mean time of 9.4 months after TIPSS creation. Conclusion The sinus-SuperFlex-Visual stent system can be safely deployed as a TIPSS device. The pressure gradient reduction was clinically sufficient to treat the patients’ symptoms, and periprocedural complications were due to the TIPSS

  17. Venous Recanalization by Metallic Stents After Failure of Balloon Angioplasty or Surgery: Four-Year Experience

    SciTech Connect

    Nazarian, Gwen K.; Austin, William R.; Wegryn, Scott A.; Bjarnason, Haraldur; Stackhouse, Daniel J.; Castaneda-Zuniga, Wilfrido R.; Hunter, David W.

    1996-04-15

    Purpose: This retrospective study describes our updated experience in treating venous stenoses and occlusions with metallic endovascular stents. Methods: Gianturco, Palmaz, and Wallstent stents were placed in 55 patients over a 4-year period. Stent sites included the subclavian veins (9), innominate veins (3), superior vena cava (4), inferior vena cava (3), iliac veins (29), femoral veins (5), and portal veins (6). The most common indications for stent placement were malignant stenoses and chronic pelvic venous occlusions. Venoplasty and/or urokinase were used as ancillary therapy. Patients were anticoagulated for 3-6 months. Follow-up included clinical assessment and duplex ultrasound. Results: Lifetable analysis shows 59%, 63%, and 72% primary, primary assisted, and secondary 1-year patency rates, respectively. The 4-year primary patency rates were the same. Duration of patency depended on the venous site. Death was a complication of stent placement in 2 patients and 12 patients died within 6 months after stent placement from primary disease progression. Although early failures were more common in stents placed across occlusions than stenoses, 1-year secondary patency rates were comparable. Primary patency rates were only slightly lower in patients with malignant obstruction than in patients with benign disease. Conclusion: Endovascular stent placement provides a nonsurgical alternative for reestablishment of venous flow and symptomatic relief in patients with benign as well as malignant venous obstruction.

  18. Frequency of Angina Pectoris After Percutaneous Coronary Intervention and the Effect of Metallic Stent Type.

    PubMed

    Gaglia, Michael A; Torguson, Rebecca; Lipinski, Michael J; Gai, Jiaxiang; Koifman, Edward; Kiramijyan, Sarkis; Negi, Smita; Rogers, Toby; Steinvil, Arie; Suddath, William O; Satler, Lowell F; Pichard, Augusto D; Waksman, Ron

    2016-02-15

    Although metallic coronary stents significantly reduce angina pectoris compared with optimal medical therapy, angina after percutaneous coronary intervention (PCI) remains frequent. We, therefore, sought to compare the incidence of any angina during the 1 year after PCI among the spectrum of commercially available metallic stents. Metallic stent type was classified as bare metal stent, Cypher, Taxus Express, Xience V, Promus Element, and Resolute. The primary end point was patient-reported angina within 1 year of PCI. Multivariable logistic regression was performed to assess the independent association of stent type with any angina at 1 year. Overall, 8,804 patients were queried in regard to angina symptoms; 32.3% experienced angina at some point in the first year after PCI. Major adverse cardiovascular events, a composite of all-cause mortality, target vessel revascularization, and Q-wave myocardial infarction, increased with angina severity: 6.8% for patients without angina, 10.0% for patients with class 1 or 2 angina, and 19.7% for patients with class 3 or 4 angina (p <0.001 for trend). After multivariable adjustment, there was no significant association between stent type and angina at 1 year after PCI. Baseline Canadian Cardiovascular Society class 3 or 4 angina, history of coronary artery bypass grafting, and history of PCI were associated with a higher likelihood of angina at 1 year; increasing age, male gender, presentation with acute coronary syndrome, and higher stented length were associated with less angina. In conclusion, metallic stent type is not associated with the occurrence of angina at up to 1 year after PCI.

  19. Long-term clinical outcomes of drug-eluting stents vs. bare-metal stents in Chinese geriatric patients

    PubMed Central

    Chan, Pak-Hei; Liu, Sha-Sha; Tse, Hung-Fat; Chow, Wing-Hing; Jim, Man-Hong; HO, Hee-Hwa; Siu, Chung Wah

    2013-01-01

    Background & objective Little is known about the relative efficacies of percutaneous coronary intervention (PCI) with drug-eluting stents (DES) and bare-metal stents (BMS) in elderly patients. The objective of this study was to evaluate the clinical outcome for geriatric patients who received either DES or BMS. Methods From January 2002 to October 2005, 199 consecutive Chinese geriatric patients (≥ 75 years old) underwent PCI with coronary DES or BMS implantation at our institution. We analyzed the major clinical end points that included all-cause mortality, cardiovascular death, myocardial infarction, target lesion revascularization (TLR), stent thrombosis, and bleeding complications. Results The three-year cumulative rates of all-cause mortality, cardiovascular death, and myocardial infarction were significantly lower in the DES group (6.3%, 3.6%, 5.4%) compared with the BMS group (16.2%, 11.5%, 14.9%; P < 0.05). No significant differences were found in the three-year cumulative rate for target lesion revascularization (6.3% vs. 4.6%, P = 0.61) or stent thrombosis (3.6% vs. 2.3%, P = 0.70). Likewise, there were no statistically significant differences in the cumulative rate for intracranial hemorrhage, or major and minor hemorrhage at three years. Conclusions DES-based PCI was associated with a significant reduction in the three-year cumulative rate of all-cause mortality, cardiovascular death, and myocardial infarction compared with BMS, without increased risk of TLR, stent thrombosis, or bleeding complications at three years in this group of Chinese geriatric patients. PMID:24454325

  20. Bare metal or drug-eluting stent implantation in last remaining vessel PCI? A serious dilemma.

    PubMed

    Zhang, Lei; Zhu, Jianhua; Kiemeneij, Ferdinand

    2009-04-01

    This case report describes the treatment of an old male diabetic patient with last remaining vessel coronary artery disease and poor left ventricular function. In presence of an old occlusion of the left main coronary artery, a subtotal stenosis of a dominant right coronary artery required angioplasty. After ample consideration it was decided to implant a bare metal stent (BMS) instead of a drug-eluting stent (DES). The major reason was the fear for early discontinuation of clopidogrel in case a drug-eluting stent was placed. The procedure and follow-up are described followed by an overview of current literature concerning similar pathology.

  1. Palliation of Malignant Biliary and Duodenal Obstruction with Combined Metallic Stenting

    SciTech Connect

    Akinci, Devrim Akhan, Okan; Ozkan, Fuat; Ciftci, Turkmen; Ozkan, Orhan S.; Karcaaltincaba, Musturay; Ozmen, Mustafa N.

    2007-11-15

    Purpose. The purpose of this study is to evaluate the efficacy of palliation of malignant biliary and duodenal obstruction with combined metallic stenting under fluoroscopy guidance. Materials and Methods. A retrospective analysis of 9 patients (6 men and 3 women) who underwent biliary and duodenal stenting was performed. The mean age of patients was 61 years (range: 42-80 years). The causes of obstruction were pancreatic carcinoma in 7 patients, cholangiocellular carcinoma in one, and duodenal carcinoma in the other. Biliary and duodenal stents were placed simultaneously in 4 patients. In other 5 patients dudodenal stents were placed after biliary stenting when the duodenal obstruction symptoms have developed. In two patients duodenal stents were advanced via transgastric approach. Results. Technical success rate was 100 %. After percutaneous biliary drainage and stenting bilirubin levels decreased to normal levels in 6 patients and in remaining 3 patients mean reduction of 71% in bilirubin levels was achieved. Tumoral ingrowth occurred in one patient and percutaneous biliary restenting was performed 90 days after the initial procedure. Of the 9 patients, 6 patients were able to tolerate solid diet, whereas 2 patients could tolerate liquid diet and one patient did not show any improvement. Mean survival periods were 111 and 73 days after biliary and duodenal stenting, respectively. Conclusion. Combined biliary and duodenal stent placement which can be performed under fluoroscopic guidance without assistance of endoscopy is feasible and an effective method of palliation of malignant biliary and duodenal obstructions. If transoral and endoscopic approaches fail, percutaneous gastrostomy route allows duodenal stenting.

  2. Vascular gene transfer from metallic stent surfaces using adenoviral vectors tethered through hydrolysable cross-linkers.

    PubMed

    Fishbein, Ilia; Forbes, Scott P; Adamo, Richard F; Chorny, Michael; Levy, Robert J; Alferiev, Ivan S

    2014-08-12

    In-stent restenosis presents a major complication of stent-based revascularization procedures widely used to re-establish blood flow through critically narrowed segments of coronary and peripheral arteries. Endovascular stents capable of tunable release of genes with anti-restenotic activity may present an alternative strategy to presently used drug-eluting stents. In order to attain clinical translation, gene-eluting stents must exhibit predictable kinetics of stent-immobilized gene vector release and site-specific transduction of vasculature, while avoiding an excessive inflammatory response typically associated with the polymer coatings used for physical entrapment of the vector. This paper describes a detailed methodology for coatless tethering of adenoviral gene vectors to stents based on a reversible binding of the adenoviral particles to polyallylamine bisphosphonate (PABT)-modified stainless steel surface via hydrolysable cross-linkers (HC). A family of bifunctional (amine- and thiol-reactive) HC with an average t1/2 of the in-chain ester hydrolysis ranging between 5 and 50 days were used to link the vector with the stent. The vector immobilization procedure is typically carried out within 9 hr and consists of several steps: 1) incubation of the metal samples in an aqueous solution of PABT (4 hr); 2) deprotection of thiol groups installed in PABT with tris(2-carboxyethyl) phosphine (20 min); 3) expansion of thiol reactive capacity of the metal surface by reacting the samples with polyethyleneimine derivatized with pyridyldithio (PDT) groups (2 hr); 4) conversion of PDT groups to thiols with dithiothreitol (10 min); 5) modification of adenoviruses with HC (1 hr); 6) purification of modified adenoviral particles by size-exclusion column chromatography (15 min) and 7) immobilization of thiol-reactive adenoviral particles on the thiolated steel surface (1 hr). This technique has wide potential applicability beyond stents, by facilitating surface engineering of

  3. The Influence of a Metal Stent on the Distribution of Thermal Energy during Irreversible Electroporation

    PubMed Central

    van den Bos, Willemien; Neal, Robert E.; van Lienden, Krijn P.; Besselink, Marc G. H.; van Gemert, Martin J. C.; van der Geld, Cees W. M.; Meijerink, Martijn R.; Klaessens, John H.; Verdaasdonk, Rudolf M.

    2016-01-01

    Purpose Irreversible electroporation (IRE) uses short duration, high-voltage electrical pulses to induce cell death via nanoscale defects resulting from altered transmembrane potential. The technique is gaining interest for ablations in unresectable pancreatic and hepatobiliary cancer. Metal stents are often used for palliative biliary drainage in these patients, but are currently seen as an absolute contraindication for IRE due to the perceived risk of direct heating of the metal and its surroundings. This study investigates the thermal and tissue viability changes due to a metal stent during IRE. Methods IRE was performed in a homogeneous tissue model (polyacrylamide gel), without and with a metal stent placed perpendicular and parallel to the electrodes, delivering 90 and 270 pulses (15–35 A, 90 μsec, 1.5 cm active tip exposure, 1.5 cm interelectrode distance, 1000–1500 V/cm, 90 pulses/min), and in-vivo in a porcine liver (4 ablations). Temperature changes were measured with an infrared thermal camera and with fiber-optic probes. Tissue viability after in-vivo IRE was investigated macroscopically using 5-triphenyltetrazolium chloride (TTC) vitality staining. Results In the gel, direct stent-heating was not observed. Contrarily, the presence of a stent between the electrodes caused a higher increase in median temperature near the electrodes (23.2 vs 13.3°C [90 pulses]; p = 0.021, and 33.1 vs 24.8°C [270 pulses]; p = 0.242). In-vivo, no temperature difference was observed for ablations with and without a stent. Tissue examination showed white coagulation 1mm around the electrodes only. A rim of vital tissue remained around the stent, whereas ablation without stent resulted in complete tissue avitality. Conclusion IRE in the vicinity of a metal stent does not cause notable direct heating of the metal, but results in higher temperatures around the electrodes and remnant viable tissue. Future studies should determine for which clinical indications IRE in the

  4. In-Graft Endovascular Stenting Repair for Supravalvular Stenosis From Aortic Rupture After Balloon-Expanding Transcatheter Aortic Valve Implantation.

    PubMed

    Furukawa, Nobuyuki; Scholtz, Werner; Haas, Nikolaus; Ensminger, Stephan; Gummert, Jan; Börgermann, Jochen

    2015-01-01

    An 81-year-old man with high-grade aortic valve stenosis and status post-coronary artery bypass grafting and supracoronary replacement of the ascending aorta was referred for transcatheter aortic valve implantation. He was in New York Heart Association class III and had dyspnea. After appropriate screening, we implanted a 29-mm SAPIEN XT valve (Edwards Lifesciences, Irvine, CA USA) through a transapical approach because of severe peripheral arterial occlusive disease. Postinterventional aortography revealed correct positioning and function of the valve and free coronary ostia but contrast extravasation in the vicinity of the interposed vascular prosthesis, resulting in severe luminal narrowing. We chose to manage the stenosis with an endovascular stent. After stenting, extravascular compression was markedly reduced, and the pressure gradient disappeared. The patient was discharged home on the 20th postoperative day. Three months later, computed tomography depicted correct positioning of both grafts. The patient's general health is good, and he is now in New York Heart Association class II. This case illustrates a complication of transcatheter aortic valve implantation specific for patients with an ascending aortic graft. Although stenting may be a good solution, as depicted by this case, self-expanding transcatheter aortic valves should be preferred in patients with ascending aortic grafts to avoid the described complication.

  5. Simulations of Self-Expanding Braided Stent Using Macroscopic Model of NiTi Shape Memory Alloys Covering R-Phase

    NASA Astrophysics Data System (ADS)

    Frost, M.; Sedlák, P.; Kruisová, A.; Landa, M.

    2014-07-01

    Self-expanding stents or stentgrafts made from Nitinol superelastic alloy are widely used for a less invasive treatment of disease-induced localized flow constriction in the cardiovascular system. The therapy is based on insertion of a stent into a blood vessel to maintain the inner diameter of the vessel; it provides highly effective results at minimal cost and with reduced hospital stays. However, since stent is an external mechanical healing tool implemented into human body for quite a long time, information on the mechanical performance of it is of fundamental importance with respect to patient's safety and comfort. Advantageously, computational structural analysis can provide valuable information on the response of the product in an environment where in vivo experimentation is extremely expensive or impossible. With this motivation, a numerical model of a particular braided self-expanding stent was developed. As a reasonable approximation substantially reducing computational demands, the stent was considered to be composed of a set of helical springs with specific constrains reflecting geometry of the structure. An advanced constitutive model for NiTi-based shape memory alloys including R-phase transition was employed in analysis. Comparison to measurements shows a very good match between the numerical solution and experimental results. Relation between diameter of the stent and uniform radial pressure on its surface is estimated. Information about internal phase and stress state of the material during compression loading provided by the model is used to estimate fatigue properties of the stent during cyclic loading.

  6. Metal allergy to everolimus-eluting cobalt chromium stents confirmed by positive skin testing as a cause of recurrent multivessel in-stent restenosis.

    PubMed

    Nakajima, Yoshifumi; Itoh, Tomonori; Morino, Yoshihiro

    2016-03-01

    A 54-year-old woman treated with cobalt-chromium everolimus eluting stents (CoCr-EES) for her left distal circumflex and diagonal branch lesions suffered from repeated in-stent restenosis in both lesions. Neointimal proliferation occurred rapidly and almost simultaneously in the two lesions. The cause was established to be metal allergy, as determined by patch tests which were strongly positive for bare metal stents and weakly positive for CoCr-EES. Following the third successive angioplasty, we initiated treatment with prednisolone (30 mg daily) and the anti-allergic and anti-proliferative drug tranilast (300 mg daily). An elective angiogram performed 3 months later showed no evidence of in-stent restenosis in any of the stented lesions. Furthermore, the patient has remained angina-free for 15 months. The unique features of this case include: (1) near-simultaneous repeated multivessel in-stent restenosis in a patient with skin test-documented metal allergy to cobalt-chromium stents; (2) adjunctive systemic medical therapy with prednisolone and tranilast appeared to terminate the malignant restenotic cycle.

  7. Role of stents and laser therapy in biliary strictures

    NASA Astrophysics Data System (ADS)

    Chennupati, Raja S.; Trowers, Eugene A.

    2001-05-01

    The most frequent primary cancers causing malignant obstructive jaundice were pancreatic cancer (57%), hilar biliary cancer (19% including metastatic disease), nonhilar biliary cancer (14%) and papillary cancer (10%). Endoscopic stenting has widely replaced palliative surgery for malignant biliary obstruction because of its lower risk and cost. Self-expandable metal stents are the preferred mode of palliation for hilar malignancies. Plastic stents have a major role in benign biliary strictures. Major complications and disadvantages associated with metallic stents include high cost, cholangitis. malposition, migration, unextractability, and breakage of the stents, pancreatitis and stent dysfunction. Dysfunction due to tumor ingrowth can be relieved by thermal methods (argon plasma coagulator therapy). We present a concise review of the efficacy of metallic stents for palliation of malignant strictures.

  8. Nine-year clinical outcomes of drug-eluting stents vs. bare metal stents for large coronary vessel lesions

    PubMed Central

    Yin, Dong; Li, Jia; Yang, Yue-Jin; Wang, Yang; Zhao, Yan-Yan; You, Shi-Jie; Qiao, Shu-Bin; Xu, Bo; Dou, Ke-Fei

    2017-01-01

    Objectives To evaluate the very long-term safety and effectiveness of drug-eluting stents (DES) compared to bare-metal stents (BMS) for patients with large coronary vessels. Methods From April 2004 to October 2006, 2407 consecutive patients undergoing de novo lesion percutaneous coronary intervention with reference vessel diameter greater than or equal to 3.5 mm at Fu Wai Hospital in Beijing, China, were prospectively enrolled into this study. We obtained 9-year clinical outcomes including death, myocardial infarction (MI), thrombosis, target lesion revascularization (TLR), target vessel revascularization (TVR), and major adverse cardiac events (MACE, the composite of death, MI, and TVR). We performed Cox's proportional-hazards models to assess relative risks of all the outcome measures after propensity match. Results After propensity scoring, 514 DES-treated patients were matched to 514 BMS-treated patients. The patients treated with BMS were associated with higher risk of TLR (HR: 2.55, 95%CI: 1.520–4.277, P = 0.0004) and TVR (HR: 1.889, 95%CI: 1.185–3.011, P = 0.0075), but the rates of death/MI and MACE were not statistically different. All Academic Research Consortium definition stent thrombosis at 9-year were comparable in the two groups. Conclusions During long-term follow-up through nine years, use of DES in patients with large coronary arteries was still associated with significant reductions in the risks of TLR and TVR.

  9. Initial experience with full-length metal stent to relieve malignant ureteral obstruction.

    PubMed

    Borin, James F; Melamud, Ori; Clayman, Ralph V

    2006-05-01

    Ureteral obstruction caused by extrinsic compression by a malignancy generally can be overcome initially with a ureteral stent. However, the long-term failure rate is high, usually necessitating placement of a nephrostomy tube. Herein, we present the initial case, in this country, of intractable ureteral obstruction managed successfully with the newly developed all-metal Resonance stent (Cook Ireland Ltd., Limerick, Ireland) constructed of MP35N alloy, a composite of nonmagnetic nickel-cobalt-chromium-molybdenum. The patient is a 64-year-old woman with metastatic breast cancer causing retroperitoneal fibrosis and ureteral obstruction diagnosed laparoscopically. The obstruction failed to respond to placement of a single 7F double-J stent and then of two 6F double-J stents in the left ureter. As a last resort, in order to avoid nephrostomy-tube placement, the 6F metal stent was placed; this provided unobstructed flow of urine, as documented on a subsequent Whitaker test and, most recently, on a renal scan, 4 months after initial stent placement.

  10. Development of a Novel Biodegradable Metallic Stent Based on Microgalvanic Effect.

    PubMed

    Frattolin, Jennifer; Barua, Rajib; Aydin, Huseyin; Rajagopalan, Sriraman; Gottellini, Luca; Leask, Richard; Yue, Stephen; Frost, David; Bertrand, Olivier F; Mongrain, Rosaire

    2016-02-01

    The implementation of biodegradable stents has the potential to revolutionize obstructive coronary artery disease treatment. Limitations still currently exist, however, that prevent biodegradable stents from replacing permanent metallic stents in the global market. The ideal combination of stent properties, including sufficient mechanical strength, controlled degradation, and biocompatibility, has yet to be realized. A novel manufacturing process is proposed that utilizes cold gas-dynamic spraying to fabricate a metal structure with significantly reduced grain size. Iron and stainless steel 316L are combined to form a novel amalgamate with enhanced mechanical strength and a controllable degradation rate, due to the resulting microgalvanic reaction. Flat specimens composed of iron and 316L are fabricated in various compositions, and mechanical and degradation tests were conducted. Femto laser techniques are utilized to produce stents composed of 80% Fe and 20% stainless steel 316L. The in vitro degradation behaviour of the stent is investigated using static and dynamic corrosion tests. It is shown that the corrosion rate can be adjusted to desired values, by varying the weight percentage of iron and stainless steel 316L within the amalgamate.

  11. Influence of metal alloy and the profile of coronary stents in patients with multivessel coronary disease

    PubMed Central

    Maurício de Abreu Filho, Luciano; da Cruz Forte, Antonio Artur; Kiyoshi Sumita, Marcos; Favarato, Desidério; César Ximenes Meireles, George

    2011-01-01

    BACKGROUND: In Brazil, despite the recommendations of the Brazilian Society of Hemodynamics and Interventional Cardiology, the National Health System has not yet approved the use of drug-eluting stents. In percutaneous coronary interventions performed in the public and part of the private health care system, bare metal stents are used as the only option. Therefore, new information on bare metal stents is of great importance. The primary endpoint was to evaluate the influence of the alloy and the profile of coronary stents on late loss and restenosis rates 6 months after implantation in patients with multivessel coronary disease. METHODS: Single center, randomized and prospective study comparison of cobalt–chromium versus stainless steel stent implantation in 187 patients with multivessel coronary disease. At least one cobalt–chromium and one stainless steel stent were implanted per patient. RESULTS: Mean age of patients was 59.5±10.1 years with a prevalence of males (66.3%) and patients with acute coronary syndrome (56%). Baseline clinical characteristics were similar with hypertension in 146 (78%), dyslipidemia in 85 (45.5%) and diabetes in 68 (36.4%). Two hundred and twenty-nine cobalt–chromium and 284 stainless steel stents were implanted. Angiographic variables showed no statistically significant difference. Angiographic follow-up to 6 months after implantation showed similar late loss and restenosis rates. CONCLUSION: The use of two different alloys, stainless steel and cobalt–chrome stents, in the same patient and in the same vessel produced similar 6-month restenosis and late loss rates. PMID:21808863

  12. Stenting of the Upper Gastrointestinal Tract: Current Status

    SciTech Connect

    Katsanos, Konstantinos; Sabharwal, Tarun Adam, Andreas

    2010-08-15

    Minimally invasive image-guided insertion of self-expanding metal stents in the upper gastrointestinal tract is the current treatment of choice for palliation of malignant esophageal or gastroduodenal outlet obstructions. A concise review is presented of contemporary stenting practice of the upper gastrointestinal tract, and the procedures in terms of appropriate patient evaluation, indications, and contraindications for treatment are analyzed, along with available stent designs, procedural steps, clinical outcomes, inadvertent complications, and future technology. Latest developments include biodegradable polymeric stents for benign disease and radioactive or drug-eluting stents for malignant obstructions.

  13. Percutaneous Intraductal Radiofrequency Ablation for Clearance of Occluded Metal Stent in Malignant Biliary Obstruction: Feasibility and Early Results

    SciTech Connect

    Pai, Madhava; Valek, Vlastimil; Tomas, Andrasina; Doros, Attila; Quaretti, Pietro; Golfieri, Rita; Mosconi, Cristina; Habib, Nagy

    2013-07-11

    PurposeThe major complication occurring with biliary stents is stent occlusion, frequently seen because of tumour in-growth, epithelial hyperplasia, and sludge deposits, resulting in recurrent jaundice and cholangitis. We report a prospective study with the results of first in man percutaneous intraductal radiofrequency (RF) ablation to clear the blocked metal stents in patients with malignant biliary obstruction using a novel bipolar RF catheter.MethodsNine patients with malignant biliary obstruction and blocked metal stents were included. These patients underwent intraductal biliary RF ablation through the blocked metal stent following external biliary decompression with an internal–external biliary drainage.ResultsAll nine patients had their stent patency restored successfully without the use of secondary stents. Following this intervention, there was no 30-day mortality, haemorrhage, bile duct perforation, bile leak, or pancreatitis. Of the nine patients, six are alive and three patients are dead with a median follow-up of 122 (range 50–488) days and a median stent patency of 102.5 (range 50–321) days. Six patients had their stent patent at the time of last follow-up or death. Three patients with stent blockage at 321, 290, and 65 days postprocedure underwent percutaneous transhepatic drain insertion and repeat ablation.ConclusionsIn this selective group of patients, it appears that this new approach is safe and feasible. Efficacy remains to be proven in future, randomized, prospective studies.

  14. Delayed Esophageal Hemorrhage Caused by a Metal Stent: Treatment with Embolization

    SciTech Connect

    Kos, Xavier; Trotteur, Genevieve; Dondelinger, Robert F.

    1998-09-15

    We report a case of life-threatening esophageal hemorrhage after metal stent implantation successfully treated by arterial embolization. An 85-year-old woman was admitted in shock secondary to massive hematemesis and melena. Recent medical history revealed esophageal cancer treated 8 weeks previously by endoesophageal radiotherapy (40 Gy) and endoscopic placement of a covered Wallstent prosthesis. Selective arteriography of the fifth posterior right intercostal artery showed massive contrast extravasation in the esophagus. Embolization was performed with 150-250-{mu}m polyvinyl alcohol particles. Follow-up at 5 months was uneventful. Arteriography and embolization are advised when severe hemorrhage occurs after esophageal implantation of metal stents.

  15. Drug eluting and bare metal stents in people with and without diabetes: collaborative network meta-analysis

    PubMed Central

    Stettler, Christoph; Allemann, Sabin; Wandel, Simon; Kastrati, Adnan; Morice, Marie Claude; Schömig, Albert; Pfisterer, Matthias E; Stone, Gregg W; Leon, Martin B; de Lezo, José Suárez; Goy, Jean-Jacques; Park, Seung-Jung; Sabaté, Manel; Suttorp, Maarten J; Kelbaek, Henning; Spaulding, Christian; Menichelli, Maurizio; Vermeersch, Paul; Dirksen, Maurits T; Cervinka, Pavel; Carlo, Marco De; Erglis, Andrejs; Chechi, Tania; Ortolani, Paolo; Schalij, Martin J; Diem, Peter; Meier, Bernhard; Windecker, Stephan

    2008-01-01

    Objective To compare the effectiveness and safety of three types of stents (sirolimus eluting, paclitaxel eluting, and bare metal) in people with and without diabetes mellitus. Design Collaborative network meta-analysis. Data sources Electronic databases (Medline, Embase, the Cochrane Central Register of Controlled Trials), relevant websites, reference lists, conference abstracts, reviews, book chapters, and proceedings of advisory panels for the US Food and Drug Administration. Manufacturers and trialists provided additional data. Review methods Network meta-analysis with a mixed treatment comparison method to combine direct within trial comparisons between stents with indirect evidence from other trials while maintaining randomisation. Overall mortality was the primary safety end point, target lesion revascularisation the effectiveness end point. Results 35 trials in 3852 people with diabetes and 10 947 people without diabetes contributed to the analyses. Inconsistency of the network was substantial for overall mortality in people with diabetes and seemed to be related to the duration of dual antiplatelet therapy (P value for interaction 0.02). Restricting the analysis to trials with a duration of dual antiplatelet therapy of six months or more, inconsistency was reduced considerably and hazard ratios for overall mortality were near one for all comparisons in people with diabetes: sirolimus eluting stents compared with bare metal stents 0.88 (95% credibility interval 0.55 to 1.30), paclitaxel eluting stents compared with bare metal stents 0.91 (0.60 to 1.38), and sirolimus eluting stents compared with paclitaxel eluting stents 0.95 (0.63 to 1.43). In people without diabetes, hazard ratios were unaffected by the restriction. Both drug eluting stents were associated with a decrease in revascularisation rates compared with bare metal stents in people both with and without diabetes. Conclusion In trials that specified a duration of dual antiplatelet therapy of six

  16. Experimental Study of Blood Laminar Flow Through a Stented Artery

    DTIC Science & Technology

    2001-10-25

    stenosis in coronary arteries. Since the 80’s, there is an alternative to the usual balloon angioplasty . Indeed, the use of tiny metallic scaffolds (named...following one: the coronary stent is placed over the angioplasty balloon and moved to the site of lesion. The stent expands with the balloon and remains...values. The coronary angioplasty is responsible of wall shear stress modification, mainly between the stent struts, at the inlet and the outlet of

  17. A new removable airway stent

    PubMed Central

    Amundsen, Tore; Sørhaug, Sveinung; Leira, Håkon Olav; Tyvold, Stig Sverre; Langø, Thomas; Hammer, Tommy; Manstad-Hulaas, Frode; Mattsson, Erney

    2016-01-01

    Background Malignant airway obstruction is a feared complication and will most probably occur more frequently in the future because of increasing cancer incidence and increased life expectancy in cancer patients. Minimal invasive treatment using airway stents represents a meaningful and life-saving palliation. We present a new removable airway stent for improved individualised treatment. Methods To our knowledge, the new airway stent is the world's first knitted and uncovered self-expanding metal stent, which can unravel and be completely removed. In an in vivo model using two anaesthetised and spontaneously breathing pigs, we deployed and subsequently removed the stents by unravelling the device. The procedures were executed by flexible bronchoscopy in an acute and a chronic setting – a ‘proof-of-principle’ study. Results The new stent was easily and accurately deployed in the central airways, and it remained fixed in its original position. It was easy to unravel and completely remove from the airways without clinically significant complications. During the presence of the stent in the chronic study, granulation tissue was induced. This tissue disappeared spontaneously with the removal. Conclusions The new removable stent functioned according to its purpose and unravelled easily, and it was completely removed without significant technical or medical complications. Induced granulation tissue disappeared spontaneously. Further studies on animals and humans are needed to define its optimal indications and future use. PMID:27608269

  18. Endoscopic multiple metal stenting for the treatment of enteral leaks near the biliary orifice: A novel effective rescue procedure

    PubMed Central

    Mutignani, Massimiliano; Dioscoridi, Lorenzo; Dokas, Stefanos; Aseni, Paolo; Carnevali, Pietro; Forti, Edoardo; Manta, Raffaele; Sica, Mariano; Tringali, Alberto; Pugliese, Francesco

    2016-01-01

    Between April 2013 and October 2015, 6 patients developed periampullary duodenal or jejunal/biliary leaks after major abdominal surgery. In all patients, percutaneous drainage of the collection or re-operation with primary surgical repair was attempted at first but failed. A fully covered enteral metal stent was placed in all patients to seal the leak. Subsequently, we cannulated the common bile duct and, in some cases, and the main pancreatic duct inserting hydrophilic guidewires through the stent after dilating the stent mesh with a dilatation balloon or breaking the meshes with Argon Plasma Beam. Finally, we inserted a fully covered biliary metal stent to drain the bile into the lumen of the enteral stent. In cases of normal proximal upper gastrointestinal anatomy, a pancreatic plastic stent was also inserted. Oral food intake was initiated when the abdominal drain outflow stopped completely. Stent removal was scheduled four to eight weeks later after a CT scan to confirm the complete healing of the fistula and the absence of any perilesional residual fluid collection. The leak resolved in five patients. One patient died two days after the procedure due to severe, pre-existing, sepsis. The stents were removed endoscopically in four weeks in four patients. In one patient we experienced stent migration causing small bowel obstruction. In this case, the stents were removed surgically. Four patients are still alive today. They are still under follow-up and doing well. Bilio-enteral fully covered metal stenting with or without pancreatic stenting was feasible, safe and effective in treating postoperative enteral leaks near the biliopancreatic orifice in our small series. This minimally invasive procedure can be implemented in selected patients as a rescue procedure to repair these challenging leaks. PMID:27606045

  19. Cost-effectiveness of drug-eluting stents versus bare-metal stents in patients undergoing percutaneous coronary intervention

    PubMed Central

    Baschet, Louise; Bourguignon, Sandrine; Marque, Sébastien; Durand-Zaleski, Isabelle; Teiger, Emmanuel; Wilquin, Fanny; Levesque, Karine

    2016-01-01

    Objective To determine the cost-effectiveness of drug-eluting stents (DES) compared with bare-metal stents (BMS) in patients requiring a percutaneous coronary intervention in France, using a recent meta-analysis including second-generation DES. Methods A cost-effectiveness analysis was performed in the French National Health Insurance setting. Effectiveness settings were taken from a meta-analysis of 117 762 patient-years with 76 randomised trials. The main effectiveness criterion was major cardiac event-free survival. Effectiveness and costs were modelled over a 5-year horizon using a three-state Markov model. Incremental cost-effectiveness ratios and a cost-effectiveness acceptability curve were calculated for a range of thresholds for willingness to pay per year without major cardiac event gain. Deterministic and probabilistic sensitivity analyses were performed. Results Base case results demonstrated that DES are dominant over BMS, with an increase in event-free survival and a cost-reduction of €184, primarily due to a diminution of second revascularisations, and an absence of myocardial infarction and stent thrombosis. These results are robust for uncertainty on one-way deterministic and probabilistic sensitivity analyses. Using a cost-effectiveness threshold of €7000 per major cardiac event-free year gained, DES has a >95% probability of being cost-effective versus BMS. Conclusions Following DES price decrease, new-generation DES development and taking into account recent meta-analyses results, the DES can now be considered cost-effective regardless of selective indication in France, according to European recommendations. PMID:27621830

  20. TIPS for refractory ascites: a 6-year single-center experience with expanded polytetrafluoroethylene-covered stent-grafts.

    PubMed

    Bercu, Zachary L; Fischman, Aaron M; Kim, Edward; Nowakowski, F Scott; Patel, Rahul S; Schiano, Thomas D; Chang, Charissa Y; Lookstein, Robert A

    2015-03-01

    OBJECTIVE. This single-center study evaluated the use of expanded polytetrafluoroethylene (ePTFE)-covered stent-grafts for transjugular intrahepatic portosystemic shunt (TIPS) placement to manage portal hypertension-related refractory ascites. MATERIALS AND METHODS. One hundred patients at a single tertiary care center in a major metropolitan hospital underwent TIPS placement with an ePTFE-covered stent-graft (Viatorr TIPS Endoprosthesis). Patients with portal hypertension-related ascites and preexisting hepatocellular carcinoma or liver transplant were excluded from the analysis. Records were reviewed for demographic characteristics, technical success of the TIPS procedures, and stent follow-up findings. Clinical results were assessed at 90- and 180-day intervals. RESULTS. Immediate technical success of the TIPS procedure was 100%. Of the 61 patients with documented follow-up, 55 (90.2%) had a partial or complete ascites response to TIPS creation. Of these 55 patients, nine experienced severe encephalopathy. Six of 61 patients (9.8%) did not experience a significant ascites response. Overall survival was 78.7% at 365-day follow-up. The 365-day survival was 84.2% for patients with a model for end-stage liver disease (MELD) score of less than 15, 67.0% for those with a score of 15-18, and 53.8% for those with a score of greater than 18 (p = 0.01). For patients with a MELD score of less than 18, the 365-day survival was 88.0% for those with an albumin value of 3 mg/dL or greater and 72.8% for those with an albumin value of less than 3 mg/dL (p = 0.04). CONCLUSION. TIPS placement using an ePTFE-covered stent-graft is an efficacious therapy for refractory ascites. Patients with preserved liver function-characterized by a MELD score of less than 15 or a MELD score of less than 18 and an albumin value of 3 mg/dL or greater-experience the greatest survival benefit.

  1. Hydrophilic surface modification of polymer vascular prostheses and metal endoluminal stents

    NASA Astrophysics Data System (ADS)

    Amery, Drew Powell

    1997-12-01

    Large diameter vascular replacements of GORE-TEXsp°ler or Dacronsp°ler are frequently used to replace damaged arteries. Poor long term patency of small diameter grafts, 6 millimeters or less, is attributed to platelet adhesion and the inability to regenerate a blood contacting surface of vascular endothelium. Metal endoluminal stents are vascular prostheses used to keep arterial lumens open following angioplasty. Complications for these implants include short term thrombogenicity and long term restenosis. This study was directed to the synthesis and characterization of more biocompatible surfaces for these devices. Gamma radiation induced-graft polymerization and radio frequency plasma activation was investigated to surface modify polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), expanded polytetrafluoroethylene (ePTFE), and 316 stainless steel. To mimic natural biocompatible tissue surfacesl a series of hydrophilic polymers were grafted onto PMMA, PET, and ePTFE. Hydrophilic graft polymers were derived from N-vinyl pyrrolidone (NVP), potassium sulfopropylacrylate (KSPA), and dimethylacrylamide, and were grafted copolymerized with several bioactive compounds in a two step modification process. Complex graft surfaces containing fibronectin (Fn), laminin (Lm), type IV collagen (IV), heparin sulfate (Hp), albumin (Alb), and a synthetic fibronectin like protein polymer (RGD) were prepared. For surface modification of endoluminal stents of 316 stainless and tantalum, a combination of RF plasma activation combined with gamma radiation induced grafting was studied. Plasma deposition of hydrophobic poly(hexane) primer layers with water plasma oxidation were examined for initial metal surface activation. Surfaces were characterized by gravimetric analysis, contact angle goniometry, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Auger depth proGling, optical microscopy (OM), and low voltage scanning electron

  2. A novel biodegradable esophageal stent: results from mechanical and animal experiments.

    PubMed

    Liu, Jin; Shang, Liang; Liu, Jiyong; Qin, Chengyong

    2016-01-01

    Biodegradable esophageal stents eliminate stent retrieval, but usually induce hyperplasia. This study investigated the properties of a novel biodegradable stent in vitro and in vivo. The degradation of the novel stent was observed in phosphate buffered saline (PBS) for 8 weeks. The radial forces, pH values, morphology, and retention rate of the intrinsic viscosity (R[η]) of the new biodegradable stent were all evaluated. In vitro, the pH values remained constant for 4 weeks and declined from weeks 4 to 8. The biodegradable threads degraded and ruptured at 6 weeks. Consequently, the radial force of the stent decreased to zero at that time. The curve of R[η] decreased with time linearly in PBS. To study the stents in vivo, we used a stricture model in which the middle esophagus of rabbits was damaged by alkali burn. Stents were inserted 2 weeks after injury and observed for 8 weeks. We assessed complications related to stent insertion, degradation of the stent, and survival of the rabbits. Two stents migrated, and one rabbit died. In the other rabbits, two stents degraded and moved into the stomach during the sixth week, five during the seventh week and one during the eighth week, respectively. One stent remained in position until the end of the study. In conclusion, our newly designed stent retained the strong radial force of self-expandable metal stents (SEMSs) and maintained the biodegradable properties of biodegradable (BD) stents.

  3. Interventional Treatment of LVAD Outflow Graft Stenosis by Introduction of Bare Metal Stents.

    PubMed

    Wiedemann, Dominik; Schlöglhofer, Thomas; Haberl, Thomas; Riebandt, Julia; Dimitrov, Kamen; Schima, Heinrich; Kastner, Johannes; Matzek, Wolfgang; Laufer, Günther; Zimpfer, Daniel

    2017-02-09

    LVAD outflow graft stenosis is a rare but life-threatening complication of MCS-therapy. Current treatment modalities (pump exchange or systemic thrombolytic therapy) are associated with significant mortality and morbidity.Implantation of bare metal stents within the stenosed outflow graft is an alternative. Herein we describe a series of 3-cases with successful stent placement. This seems to be safe and successful however correct and early diagnosis of outflow stenosis can be challenging. Information provided by the HeartWare HVAD logfiles are extremely helpful for diagnosis.

  4. Transhepatic Insertion of a Metallic Stent for the Relief of Malignant Afferent Loop Obstruction

    SciTech Connect

    Caldicott, David G.E.; Ziprin, Paul; Morgan, Robert

    2000-03-15

    A 65-year-old man with a polya gastrectomy presented with biliary obstruction. Percutaneous cholangiography indicated strictures of the distal common bile duct and afferent duodenal loop due to an inoperable carcinoma of the head of the pancreas. The patient was unfit for bypass surgery, and a previous gastrectomy precluded endoscopic intervention. Successful palliation of the biliary obstruction was achieved by placing metallic stents across the duodenal and biliary strictures via the transhepatic route. The use of stents for gastrointestinal stricture is reviewed.

  5. Vascular Gene Transfer from Metallic Stent Surfaces Using Adenoviral Vectors Tethered through Hydrolysable Cross-linkers

    PubMed Central

    Fishbein, Ilia; Forbes, Scott P.; Adamo, Richard F.; Chorny, Michael; Levy, Robert J.; Alferiev, Ivan S.

    2014-01-01

    In-stent restenosis presents a major complication of stent-based revascularization procedures widely used to re-establish blood flow through critically narrowed segments of coronary and peripheral arteries. Endovascular stents capable of tunable release of genes with anti-restenotic activity may present an alternative strategy to presently used drug-eluting stents. In order to attain clinical translation, gene-eluting stents must exhibit predictable kinetics of stent-immobilized gene vector release and site-specific transduction of vasculature, while avoiding an excessive inflammatory response typically associated with the polymer coatings used for physical entrapment of the vector. This paper describes a detailed methodology for coatless tethering of adenoviral gene vectors to stents based on a reversible binding of the adenoviral particles to polyallylamine bisphosphonate (PABT)-modified stainless steel surface via hydrolysable cross-linkers (HC). A family of bifunctional (amine- and thiol-reactive) HC with an average t1/2 of the in-chain ester hydrolysis ranging between 5 and 50 days were used to link the vector with the stent. The vector immobilization procedure is typically carried out within 9 hr and consists of several steps: 1) incubation of the metal samples in an aqueous solution of PABT (4 hr); 2) deprotection of thiol groups installed in PABT with tris(2-carboxyethyl) phosphine (20 min); 3) expansion of thiol reactive capacity of the metal surface by reacting the samples with polyethyleneimine derivatized with pyridyldithio (PDT) groups (2 hr); 4) conversion of PDT groups to thiols with dithiothreitol (10 min); 5) modification of adenoviruses with HC (1 hr); 6) purification of modified adenoviral particles by size-exclusion column chromatography (15 min) and 7) immobilization of thiol-reactive adenoviral particles on the thiolated steel surface (1 hr). This technique has wide potential applicability beyond stents, by facilitating surface engineering of

  6. Construction of Transjugular Intrahepatic Portosystemic Shunt: Bare Metal Stent/Stent-graft Combination versus Single Stent-graft, a Prospective Randomized Controlled Study with Long-term Patency and Clinical Analysis

    PubMed Central

    Wang, Chang-Ming; Li, Xuan; Fu, Jun; Luan, Jing-Yuan; Li, Tian-Run; Zhao, Jun; Dong, Guo-Xiang

    2016-01-01

    Background: Balanced adjustment of the portal vein shunt volume during a transjugular intrahepatic portosystemic shunt (TIPS) is critical for maintaining liver perfusion and decreasing the incidence of liver insufficiency. A stent-graft is proved to be superior to a bare metal stent (BMS) for the construction of a TIPS. However, the clinical results of the combination application of stents and stent-grafts have not been determined. This study aimed to compare the technique of using a combination of stents and stent-grafts with using a single stent-graft to construct a TIPS. Methods: From April 2011 to November 2014, a total of fifty patients were randomly assigned to a stents-combination group (Group I, n = 28) or a stent-graft group (Group II, n = 22). Primary patency rates were calculated. Clinical data, including the technical success rate, bleeding control results, incidence of encephalopathy, liver function preservation, and survival rate, were assessed. Results: Technically, the success rate was 100% for both groups. The primary patency rates at 1, 2, and 3 years for Group I were 96%, 84%, and 77%, respectively; for Group II, they were 90%, 90%, and 78%, respectively. The survival rates at 1, 2, and 3 years for Group I were 79%, 74%, and 68%, respectively; for Group II, they were 82%, 82%, and 74%, respectively. The incidence of hepatic encephalopathy was 14.3% for Group I and 13.6% for Group II. The Child-Pugh score in Group I was stable at the end of the follow-up but had significantly increased in Group II (t = −2.474, P = 0.022). Conclusions: The construction of a TIPS with either the single stent-graft or BMS/stent-graft combination is effective for controlling variceal bleeding. The BMS/stent-graft combination technique is superior to the stent-graft technique in terms of hepatic function preservation indicated by the Child-Pugh score. However, considering the clinical results of the TIPS, the two techniques are comparable in their primary shunt

  7. Successful Endovascular Repair of an Iatrogenic Perforation of the Superficial Femoral Artery Using Self-Expanding Nitinol Supera Stents in a Patient with Acute Thromboembolic Limb Ischemia.

    PubMed

    Eisele, Tom; Muenz, Benedikt M; Korosoglou, Grigorios

    2016-01-01

    The treatment of acute thromboembolic limb ischemia includes well-established surgical thrombectomy procedures and, in recent times, also percutaneous rotational thrombectomy using Straub Rotarex® system. This modality not only enables efficient treatment of such thrombotic occlusion but also in rare cases may imply the risk of perforation of the occluded artery. Herein, we report the case of a perforation of the superficial femoral artery (SFA) in an elderly female patient with thromboembolic limb ischemia. The perforation was successfully treated by implantation of self-expanding nitinol Supera stents and without the need for implantation of a stent graft.

  8. Successful Endovascular Repair of an Iatrogenic Perforation of the Superficial Femoral Artery Using Self-Expanding Nitinol Supera Stents in a Patient with Acute Thromboembolic Limb Ischemia

    PubMed Central

    Eisele, Tom; Muenz, Benedikt M.

    2016-01-01

    The treatment of acute thromboembolic limb ischemia includes well-established surgical thrombectomy procedures and, in recent times, also percutaneous rotational thrombectomy using Straub Rotarex® system. This modality not only enables efficient treatment of such thrombotic occlusion but also in rare cases may imply the risk of perforation of the occluded artery. Herein, we report the case of a perforation of the superficial femoral artery (SFA) in an elderly female patient with thromboembolic limb ischemia. The perforation was successfully treated by implantation of self-expanding nitinol Supera stents and without the need for implantation of a stent graft. PMID:27213074

  9. Ureteroiliac Artery Fistula Caused by a Metallic Memokath Ureteral Stent in a Radiation-Induced Ureteral Stricture

    PubMed Central

    Das, Krishanu; Ordones, Flavio; Welikumbura, Sumudu

    2016-01-01

    Abstract Background: Memokath 051™ stents are increasingly used for management of benign and malignant ureteral strictures refractory to management with single or tandem polymeric Double-J ureteral stents. Migration, encrustation, and difficulty in extraction during stent exchange are the chief problems reported so far with these thermoexpandable metallic stents. We report an unusual complication of ureteroexternal iliac artery fistula (UEAF) caused by Memokath stent inserted for radiation-induced ureteral stricture. Case Presentation: A 71-year-old male with history of colorectal cancer (underwent extirpative surgery + chemoradiotherapy) and subsequently radiation-induced ureteral stricture had bilateral Memokath ureteral stents inserted. Three months later, he presented with sepsis and hemodynamic instability secondary to UEAF, confirmed on angiography. A covered vascular stent was inserted as an immediate management. Conclusion: Memokath stent insertion in radiation-induced ureteral strictures may be associated with an increased risk of erosion and the rare potential complication of UEAF. This potential risk needs to be considered in the overall setting of such strictures and the difficulty in treating them. Prompt imaging (angiography) and placement of an endovascular stent are the ideal immediate options in such cases. PMID:27785465

  10. Elastic Deformation Properties of Implanted Endobronchial Wire Stents in Benign and Malignant Bronchial Disease: A Radiographic In Vivo Evaluation

    SciTech Connect

    Hautmann, Hubert; Rieger, Johannes; Huber, Rudolf M.; Pfeifer, Klaus J.

    1999-03-15

    Purpose: To evaluate the long-term mechanical behavior in vivo of expandable endobronchial wire stents, we imaged three different prostheses in the treatment of tracheobronchial disease. Methods: Six patients with bronchial stenoses (three benign, three malignant) underwent insertion of metallic stents. Two self-expandable Wallstents, two balloon-expandable tantalum Strecker stents and two self-expandable nitinol Accuflex stents were used. Measurements of deformation properties were performed during voluntary cough by means of fluoroscopy, at 1 month and 7-10 months after implantation. The procedures were videotaped, their images digitized and the narrowing of stent diameters calculated at intervals of 20 msec. Results: After stent implantation all patients improved with respect to ventilatory function. Radial stent narrowing during cough reached 53% (Wallstent), 59% (tantalum Strecker stent), and 52% (nitinol Accuflex stent) of the relaxed post-implantation diameter. Stent compression was more marked in benign compared with malignant stenoses. In the long term permanent deformation occurred with the tantalum Strecker stents; the other stents were unchanged. Conclusion: Endobronchial wire stents can be helpful in the treatment of major airway collapse and obstructing bronchial lesions. However, evidence of material fatigue as a possible effect of exposure to recurrent mechanical stress on the flexible mesh tube may limit their long-term use. This seems to be predominantly important in benign bronchial collapse.

  11. Spontaneous Evacuation of a Vascular Metallic Stent through a Graft-Duodenal Fistula with Concomitant Non-Surgical Fistula Closure

    PubMed Central

    Inoue, Hidenori; Motohashi, Shinya; Uchiyama, Hirotomo; Akasaka, Junetsu

    2016-01-01

    We report a patient who developed ileus caused by vascular stent migration into the duodenum with periprosthetic retroperitoneal abscess. The patient previously underwent removal of an infected abdominal aortic aneurysm with concomitant axillobifemoral arterial reconstruction. An occlusion of the graft leg was treated by a unilateral aortoiliac bypass where endovascular surgery with a metallic stent was later needed. The abscess and ileus were vigorously drained. Following the spontaneous evacuation of the metallic stent via the digestive tract, the abscess was completely drained and fistula closure was achieved without surgical intervention. The patient has remained healthy 6 years thereafter. PMID:28018510

  12. MRI Artifacts of a Metallic Stent Derived From a Human Aorta Specimen

    SciTech Connect

    Soto, M. E.; Flores, P.; Marrufo, O.; Hidalgo, S. S.; Rodriguez, A. O.

    2010-12-07

    Magnetic resonance imaging has proved to be a useful technique to get images of the whole body. However, the presence of ferromagnetic material can cause susceptibility artifacts, which result from microscopic gradients that occur near the boundaries between areas displaying different magnetic susceptibility. These gradients cause dephasing of spins and frequency shifts in the surrounding tissues. Intravoxel dephasing and spatial mis-registration can degrade image quality. An aorta with a metallic stent was preserved in formaldehyde at 10% inside acrylic cylinders and used to obtain MR images. We tested pulsed spin echo and gradient echo sequences to improve image quality. All experiments were performed on a 7T/21 cm Varian system (Varian, Inc, Palo Alto, CA) equipped with Direct Drive technology and a 16-rung birdcage coil transceiver. The presence of metallic stents produces a lack of signal that might give falsely reassuring appearances within the vessel lumen.

  13. Understanding the requirements of self-expandable stents for heart valve replacement: Radial force, hoop force and equilibrium.

    PubMed

    Cabrera, María Sol; Oomens, Cees W J; Baaijens, Frank P T

    2017-04-01

    A proper interpretation of the forces developed during stent crimping and deployment is of paramount importance for a better understanding of the requirements for successful heart valve replacement. The present study combines experimental and computational methods to assess the performance of a nitinol stent for tissue-engineered heart valve implantation. To validate the stent model, the mechanical response to parallel plate compression and radial crimping was evaluated experimentally. Finite element simulations showed good agreement with the experimental findings. The computational models were further used to determine the hoop force on the stent and radial force on a rigid tool during crimping and self-expansion. In addition, stent deployment against ovine and human pulmonary arteries was simulated to determine the hoop force on the stent-artery system and the equilibrium diameter for different degrees of oversizing.

  14. Long-Term Clinical Outcomes Following Drug-eluting and Bare Metal Stenting in Massachusetts

    PubMed Central

    Mauri, Laura; Silbaugh, Treacy S; Wolf, Robert E; Zelevinsky, Katya; Lovett, Ann; Zhou, Zheng; Resnic, Frederic S; Normand, Sharon-Lise T

    2010-01-01

    Background Drug-eluting stents (DES) reduce the need for repeat revascularization, but their long term safety relative to bare metal stents (BMS) in general use remains uncertain. We sought to compare the clinical outcome of patients treated with DES vs. BMS. Methods and Results All adults undergoing percutaneous coronary intervention (PCI) with stenting between April 1, 2003 and September 30, 2004 at non-US governmental hospitals in Massachusetts were identified from a mandatory state database. Patients were classified according to stent types used from the index admission. Clinical and procedural risk factors were collected prospectively. Risk-adjusted mortality, myocardial infarction, and revascularization rate differences (DES-BMS) were estimated through propensity score matching without replacement. 11556 patients were treated with DES and 6237 treated with BMS with unadjusted 2 year mortality of 7.0% and 12.6% respectively (p<0.0001). In 5549 DES patients matched to 5549 BMS patients, 2 year risk-adjusted mortality rates were 9.8% and 12.0% (p=0.0002), myocardial infarction, 8.3% vs. 10.3% (p=0.0005), and target vessel revascularization, 11.0% vs. 16.8% (p<0.0001). Conclusions DES treatment was associated with lower mortality, myocardial infarction, and target vessel revascularization compared with BMS treatment in similar patients in a matched population based study. Comprehensive follow-up in this inclusive population is warranted to identify if similar safety and efficacy remain beyond 2 years. PMID:18852368

  15. The Relationship Between Lymphocyte-to-Monocyte Ratio and Bare-Metal Stent In-Stent Restenosis in Patients With Stable Coronary Artery Disease.

    PubMed

    Murat, Sani Namik; Yarlioglues, Mikail; Celik, Ibrahim Etem; Kurtul, Alparslan; Duran, Mustafa; Kilic, Alparslan; Oksuz, Fatih

    2017-04-01

    In-stent restenosis (ISR) is a common clinical problem in patients with coronary artery disease treated with percutaneous coronary intervention. Inflammatory process plays a pivotal role in the development of ISR. Both lymphocytes and monocytes are associated with inflammatory status. Recently, it has been shown that the lymphocyte-to-monocyte ratio (LMR) is a novel inflammatory marker. We aimed to investigate the association of serum LMR levels and ISR in patients undergoing bare-metal stent (BMS) implantation. The study included 273 patients (aged 61 ± 11 years, 66.5% men) with a history of BMS implantation and a further control coronary angiography due to stable angina pectoris. Patients were divided into 2 groups: patients with and without ISR. The LMR levels were significantly lower in patients with ISR than in those without ISR (2.50 ± 0.95 vs 3.87 ± 1.51, respectively, P < .001). On multivariate logistic regression analysis, the LMR was independently associated with ISR (odds ratio [OR]: 0.310, 95% confidence interval: 0.166-0.579, P < .001) together with high-sensitivity C-reactive protein (OR: 1.244, P = .008), reason for stent implantation (OR: 6.566, P = .003), stent diameter (OR: 0.015, P < .001), and stent length (OR: 1.137, P = .007). In conclusion, LMR levels are inversely related to ISR in patients treated with BMS implantation.

  16. ePTFE/FEP-Covered Metallic Stents for Palliation of MalignantBiliary Disease: Can Tumor Ingrowth Be Prevented?

    SciTech Connect

    Hatzidakis, Adam Krokidis, Miltiadis; Kalbakis, Kostantinos; Romanos, Jiannis; Petrakis, Ioannis; Gourtsoyiannis, Nicholas

    2007-09-15

    Purpose. To determine the application and clinical effectiveness of ePTFE/FEP-covered metallic stents for palliation of malignant biliary disease, and to evaluate the efficiency of stent coverage in preventing tumor ingrowth. Methods. During a 3-year period, 36 patients with malignant obstructive jaundice were treated with ePTFE/FEP-covered stents, with or without proximal side holes. The stricture was located in the lower common bile duct (CBD) in 18 cases, the upper CBD in 9, the lower common hepatic duct (CHD) in 6, and the upper CHD in 3 patients. Results.Thirty-seven covered stents were percutaneously implanted. The technical success rate was 97%. Reintervention was required in 6 cases. The 30-day mortality rate was 40%, not procedure-related. Mean survival was 128 days. Primary patency rates were 100%,55.5%, and 25% at 3, 6, and 12 months, respectively, while the assisted patency rate was 100% at 12 months. Stents without side holes had higher primary patency rates compared with those with side holes, where occlusion was always due to tumor ingrowth. Tumor ingrowth did not occur in the completely covered stents. No stent dysfunction due to sludge incrustation was found.Complications were 1 case of arterial laceration that occurred during percutaneous transhepatic cholangiography, and a subcapsular hematoma and 1 case of bile peritonitis, that both occurred during primary stenting. No complications followed the secondary stenting technique. Conclusion. ePTFE/FEP-covered metallic stents are safe and effective for palliation of malignant biliary disease. The presence of the ePTFE/FEP coating is likely to prevent from tumor ingrowth.

  17. Aortic Pseudoaneurysm Formation Following Concurrent Chemoradiotherapy And Metallic Stent Insertion in a Patient With Esophageal Cancer

    PubMed Central

    Hou, Pei-Yu; Teng, Chung-Jen; Chung, Chen-Shuan; Liu, Chao-Yu; Huang, Chun-Chieh; Chang, Miu-Hsiang; Shueng, Pei-Wei; Hsieh, Chen-Hsi

    2015-01-01

    Abstract Aortic pseudoaneurysm formation subsequent to concurrent chemoradiotherapy (CCRT) for esophageal cancer patient with esophageal metallic stent insertion is a rare condition. A 52-year-old man with esophageal cancer, cT4N1M0, stage IIIC, was treated with concurrent weekly cisplatin (30 mg/m2) and 5-Fluorouracil (500 mg/m2) as well as radiotherapy (50.4 Gy in 28 fractions) for 6 weeks. An esophageal metallic stent was inserted for dysphagia 1 week after initiation of CCRT. During the treatment regimen, the platelet count dropped to less than 200 × 103 /μL. One month after the completion of CCRT, chest CT revealed the presence of an aortic pseudoaneurysm as well as aortoesophageal fistulas. A thoracic aortic endografting was performed and the patient responded well to surgery. However, the patient died 2 months later due to a nosocomial infection. Multimodality treatment for esophageal cancer comprising cisplatin-based CCRT and esophageal metallic stent placement near a great vessel may increase the risk of pseudoaneurysm formation. PMID:25997064

  18. Self-Expandable Stent for Repairing Coarctation of the Left-Circumferential Aortic Arch with Right-sided Descending Aorta and Aberrant Right Subclavian Artery with Kommerell's Aneurysm.

    PubMed

    Khajali, Zahra; Sanati, Hamid Reza; Pouraliakbar, Hamidreza; Mohebbi, Bahram; Aeinfar, Kamran; Zolfaghari, Reza

    2017-01-01

    Endovascular treatment offers a great advantage in the management of main arteries stenoses. However, simultaneous presence of a group of anomalies may complicate the situation. Here we present a case of 21-year-old man with aortic coarctation. Radiographic imaging and angiography demonstrated aortic coarctation of the left-circumferential aortic arch, right-sided descending aorta, and Kommerell's diverticulum at the origin of right subclavian artery. These anomalies have rarely been reported to concurrently exist in the same case and the treatment is challenging. Percutaneous treatment for repair of aortic coarctation was successfully performed with deployment of self-expanding nitinol stents. Follow-up demonstrated the correction of blood pressure and improvement of the symptoms. It appears that deployment of self-expandable nitinol stents present a viable option for the management of coarcted aorta in patients having all or some of these anomalies together.

  19. Palliation of Pyloric Stenosis Caused by Gastric Cancer Using an Endoscopically Placed Covered Ultraflex Stent: Covered Stent Inside an Occluded Uncovered Stent

    SciTech Connect

    Nakamura, Toshifumi; Kitagawa, Mutsuo; Takehira, Yasunori; Yamada, Masami; Nishiwaki, Yoshiro; Nakamura, Hirotoshi

    2000-07-15

    A 71-year-old man developed pyloric stenosis caused by gastric cancer. Vomiting and nausea resolved after the insertion of an uncovered Ultraflex stent (length 10 cm, inner diameter 18u23 mm) through a 7-cm-long stenosis, and the patient was able to eat a soft diet. After 6 weeks, stent occlusion occurred due to tumor ingrowth and accumulation of food residue. Endoscopic observation showed a very narrow residual lumen. A covered Ultraflex stent (length 10 cm, inner diameter 18u23 mm) was inserted through the first stent and expanded to its maximum diameter over the next 2 days. The patient's vomiting and nausea improved rapidly. He died 6 months after the second stenting procedure, from metastatic tumor spread, having remained free of nausea and vomiting. In this case, a covered metallic stent prevented tumor ingrowth and maintained gastrointestinal patency.

  20. Feasibility, safety, and preliminary efficacy of a novel ePTFE-covered self-expanding stent in saphenous vein graft lesions: the Symbiot II trial.

    PubMed

    Laarman, Gerrit J; Kiemeneij, Ferdinand; Mueller, Ralf; Guagliumi, Giuglio; Cobaugh, Michael; Serruys, Patrick W

    2005-03-01

    Compared with percutaneous interventions in native coronary arteries, revascularization of saphenous vein graft (SVG) lesions is associated with increased rates of immediate and long-term major adverse cardiac events (MACE). The Symbiot II trial was a multicenter prospective study designed to evaluate the feasibility and safety of a novel self-expanding polytetrafluoroethylene (ePTFE)-covered stent in the treatment of de novo and restenotic SVG lesions. The primary endpoint was MACE through 30 days postprocedure. Successful Symbiot stent deployment was achieved in 75 of 77 patients (97.4%) with SVG lesions < or = 35 mm in length (visual assessment). The procedural success rate (defined as < 30% residual stenosis at the target site and no clinical complications) was 83%, and all study device procedures provided grade 3 TIMI flow postprocedure. Within the first 30 days postprocedure, four patients (5.2%) experienced MACE (defined as death, Q-wave or non-Q-wave myocardial infarction, and clinically driven target vessel revascularization), of whom three patients (3.9%) experienced periprocedural non-Q-wave myocardial infarction. No subacute stent thrombosis was observed over the 6-month follow-up period. No relevant luminal loss at the target site (mean, 0.3 +/- 0.9 mm) was observed in the 58 patients (77.3% of enrolled patients) who underwent quantitative coronary angiography at 6 months. The incidences of binary in-stent restenosis, in-segment restenosis, and target vessel failure (defined as acute and late-term MACE through 6 months postprocedure) were low (7.0%, 8.6%, and 14.3%, respectively). The Symbiot self-expanding ePTFE membrane-covered stent was associated with a high procedural success rate (97.4%), low incidences of MACE at 30 days (5.2%) and 6 months (14.3%), suggesting that it is safe and effective in the treatment of SVG disease.

  1. Fe-Mn alloys for metallic biodegradable stents: degradation and cell viability studies.

    PubMed

    Hermawan, Hendra; Purnama, Agung; Dube, Dominique; Couet, Jacques; Mantovani, Diego

    2010-05-01

    Biodegradable stents have shown their potential to be a valid alternative for the treatment of coronary artery occlusion. This new class of stents requires materials having excellent mechanical properties and controllable degradation behaviour without inducing toxicological problems. The properties of the currently considered gold standard material for stents, stainless steel 316L, were approached by new Fe-Mn alloys. The degradation characteristics of these Fe-Mn alloys were investigated including in vitro cell viability. A specific test bench was used to investigate the degradation in flow conditions simulating those of coronary artery. A water-soluble tetrazolium test method was used to study the effect of the alloy's degradation product to the viability of fibroblast cells. These tests have revealed the corrosion mechanism of the alloys. The degradation products consist of metal hydroxides and calcium/phosphorus layers. The alloys have shown low inhibition to fibroblast cells' metabolic activities. It is concluded that they demonstrate their potential to be developed as degradable metallic biomaterials.

  2. The full metallic double-pigtail ureteral stent: Review of the clinical outcome and current status

    PubMed Central

    Kallidonis, Panagiotis S.; Georgiopoulos, Ioannis S.; Kyriazis, Iason D.; Kontogiannis, Stavros; Al-Aown, Abdulrahman M.; Liatsikos, Evangelos N.

    2015-01-01

    The full metallic double-J ureteral stent (MS) was introduced as a method for providing long-term drainage in malignant ureteral obstruction. Experimental evaluation of the MS revealed that its mechanical features allow efficient drainage in difficult cases, which could not be managed by the insertion of a standard polymeric double-J stent. Clinical experience with the MS showed controversial results. Careful patient selection results in efficient long-term management of malignant ureteral obstruction. The use of the MS should also be considered in selected benign cases. Major complications are uncommon and the minor complications should not hinder its use. Experience in pediatric patients is limited and warrants additional study. The cost-effectiveness of the MS seems to be appropriate for long-term treatment. Further investigation with comparative clinical trials would document the outcome more extensively and establish the indications as well as the selection criteria for the MS. PMID:25624569

  3. Self-Expandable Stent Placement in Infrapopliteal Arteries After Unsuccessful Angioplasty Failure: One-Year Follow-up

    SciTech Connect

    Peregrin, J. H. Smirova, S.; Koznar, B.; Novotny, J.; Kovac, J.; Lastovickova, J.; Skibova, J.

    2008-09-15

    The purpose of this prospective study was to evaluate whether stent placement in infrapopliteal arteries is helpful in failed percutaneous transluminal angioplasty (PTA). Infrapopliteal PTA was performed in 70 arteries of 66 patients with chronic critical lower limb ischemia. The group comprised 55 males and 11 females, with an average age of 63.4 (range, 42-82) years. Diabetes mellitus was present in 92.4% of patients. Only the palpable anterior tibial and posterior tibial arteries were evaluated. Stents (Xpert stent; Abbot Vascular, Redwood City, CA, USA) were placed in 16 arteries where PTA was not successful (the failure was defined as residual stenosis >30% after PTA). In 54 arteries simple PTA was performed and was technically successful. Twenty-four nondilated arteries with no significant stenosis served as a comparison group. The 12-month patency rate was evaluated according to a combination of palpation and Doppler ultrasound. In all cases stent placement restored the flow in the artery immediately after unsuccessful PTA. Twelve-month follow-up showed a patency rate of 82% in the PTA group, 78% in the stent group, and 69% in the comparison group. We conclude that stent placement in the case of unsuccessful infrapopliteal PTA changed technical failure to success and restored flow in the dilated artery. At 12-month follow-up the patency rate of infrapopliteal arteries stented for PTA failure did not differ significantly either from nonstented arteries with an optimal PTA result or from a comparison group of nonintervened arteries.

  4. Fabrication and In Vitro Deployment of a Laser-Activated Shape Memory Polymer Vascular Stent

    SciTech Connect

    Baer, G M; Small IV, W; Wilson, T S; Benett, W J; Matthews, D L; Hartman, J; Maitland, D J

    2007-04-25

    Vascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel). Most vascular stents are metallic and are deployed either by balloon expansion or by self-expansion. A shape memory polymer (SMP) stent may enhance flexibility, compliance, and drug elution compared to its current metallic counterparts. The purpose of this study was to describe the fabrication of a laser-activated SMP stent and demonstrate photothermal expansion of the stent in an in vitro artery model. A novel SMP stent was fabricated from thermoplastic polyurethane. A solid SMP tube formed by dip coating a stainless steel pin was laser-etched to create the mesh pattern of the finished stent. The stent was crimped over a fiber-optic cylindrical light diffuser coupled to an infrared diode laser. Photothermal actuation of the stent was performed in a water-filled mock artery. At a physiological flow rate, the stent did not fully expand at the maximum laser power (8.6 W) due to convective cooling. However, under zero flow, simulating the technique of endovascular flow occlusion, complete laser actuation was achieved in the mock artery at a laser power of {approx}8 W. We have shown the design and fabrication of an SMP stent and a means of light delivery for photothermal actuation. Though further studies are required to optimize the device and assess thermal tissue damage, photothermal actuation of the SMP stent was demonstrated.

  5. Hemocompatibility Improvement of Chromium-Bearing Bare-Metal Stent Platform After Magnetoelectropolishing

    NASA Astrophysics Data System (ADS)

    Rokicki, Ryszard; Haider, Waseem; Maffi, Shivani Kaushal

    2015-01-01

    Research was undertaken to determine the influence of the increased content of chromium in the outermost passive layer of magneto-electrochemically refined Co-Cr alloy L-605 surface on its hemocompatibility. The chemistry, roughness, surface energy, and wettability of conventionally electropolished (EP) and magnetoelectropolished (MEP) samples were studied with x-ray photoelectron spectroscopy (XPS), open circuit potential, atomic force microscopy, and contact angle meter. In vitro hemocompatibility of tested material surfaces was assessed using two important indicators of vascular responses to biomaterial, namely endothelialization and platelets adhesion. The endothelialization was assessed by seeding and incubating samples with human umbilical vein endothelial cells (HUVEC) for 3 days before counting and observing them under a fluorescent microscope. The platelet (rich plasma blood) adhesion and activation test on EP and MEP L-605 alloy surfaces was assessed using a laser scanning confocal microscope. The XPS analysis of MEP samples showed significant enrichment of the passive layer with Cr and O when compared with the EP one. The amount of other elements in the passive layer did not show a significant difference between EP and MEP treatments. The adhesion of HUVEC cells shows remarkable affinity to surfaces enriched in Cr (MEP) with almost 100% confluency. In addition, the number of platelets that adhered to standard EP surfaces was higher compared to the MEP surface. The present study shows that the chromium-enriched surface of cobalt-chromium alloy L-605 by the magnetoelectropolishing process tremendously improves surface hemocompatibility with regard to stent functionality by enhanced endothelialization and lower platelet adhesion and should be taken under consideration as an alternative surface of biodegradable polymer drug-eluting stents, polymer-free drug-eluting stents as well as bare-metal stents.

  6. Prophylactic stenting for esophageal stricture prevention after endoscopic submucosal dissection

    PubMed Central

    Shi, Ke-Da; Ji, Feng

    2017-01-01

    Endoscopic submucosal dissection (ESD) of superficial esophageal cancer has been increasingly used as an alternative to surgery because it is minimally invasive and has a high rate of en bloc resection. However, a high rate of esophageal stricture is observed after ESD for large lesions, which can dramatically decrease the patient’s quality of life. Stricture prevention is necessary to allow for endoscopic therapy to expand. We, herein, review the most recent evidence and discuss the role of the metallic self-expandable stent and the biodegradable stent in esophageal stricture prevention. Limited studies suggested that prophylactic stenting could reduce the stricture rate without increasing the number of complications. In addition, the number of bougie dilation procedures was significantly lower with stent placement. Esophageal stenting is a promising option for post-ESD stricture prevention. However, current evidence is too preliminary to formulate practice standards. Future studies are needed to further validate the efficacy and safety of prophylactic stenting and determine the best strategy for stricture prevention. Stent migration is the most common complication. A new stent that has advantages of a low migration rate and minimal tissue reaction will need to be developed. Therefore, randomized controlled trials with long-term follow-up periods are required before prophylactic stenting could be considered a valid option to prevent post-ESD stricture. PMID:28246466

  7. Multidetector-Row Computed Tomography in the Evaluation of Transjugular Intrahepatic Portosystemic Shunt Performed with Expanded-Polytetrafluoroethylene-Covered Stent-Graft

    SciTech Connect

    Fanelli, Fabrizio Bezzi, Mario; Bruni, Antonio; Corona, Mario; Boatta, Emanuele; Lucatelli, Pierleone; Passariello, Roberto

    2011-02-15

    We assessed, in a prospective study, the efficacy of multidetector spiral computed tomography (MDCT) in the evaluation of transjugular intrahepatic portosystemic shunt (TIPS) patency in patients treated with the Viatorr (Gore, Flagstaff, AZ) expanded-polytetrafluoroethylene (e-PTFE)-covered stent-graft. Eighty patients who underwent TIPS procedure using the Viatorr self-expanding e-PTFE stent-graft were evaluated at follow-up of 1, 3, 6, and 12 months with clinical and laboratory tests as well as ultrasound-color Doppler (USCD) imaging. In case of varices, upper gastrointestinal endoscopy was also performed. In addition, the shunt was evaluated using MDCT at 6 and 12 months. In all cases of abnormal findings and discrepancy between MDCT and USCD, invasive control venography was performed. MDCT images were acquired before and after injection of intravenous contrast media on the axial plane and after three-dimensional reconstruction using different algorithms. MDCT was successfully performed in all patients. No artefacts correlated to the Viatorr stent-graft were observed. A missing correlation between UCSD and MDCT was noticed in 20 of 80 (25%) patients. Invasive control venography confirmed shunt patency in 16 (80%) cases and shunt malfunction in 4 (20%) cases. According to these data, MDCT sensitivity was 95.2%; specificity was 96.6%; and positive (PPV) and negative predictive values (NPV) were 90.9 and 98.2%, respectively. USCD sensitivity was 90%; specificity was 75%; and PPV and NPV were 54.5 and 95.7%, respectively. A high correlation (K value = 0.85) between MDCT and invasive control venography was observed. On the basis of these results, MDCT shows superior sensitivity and specificity compared with USCD in those patients in whom TIPS was performed with the Viatorr stent-graft. MDCT can be considered a valid tool in the follow-up of these patients.

  8. Long-term Outcomes of Drug-eluting versus Bare-metal stent for ST-elevation Myocardial Infarction

    PubMed Central

    Wang, Liping; Wang, Hongyun; Dong, Pingshuan; Li, Zhuanzhen; Wang, Yanyu; Duan, Nana; Zhao, Yuwei; Wang, Shaoxin

    2014-01-01

    Background Long-term outcomes of drug-eluting stents (DES) versus bare-metal stents (BMS) in patients with ST-segment elevation myocardial infarction (STEMI) remain uncertain. Objective To investigate long-term outcomes of drug-eluting stents (DES) versus bare-metal stents (BMS) in patients with ST-segment elevation myocardial infarction (STEMI). Methods We performed search of MEDLINE, EMBASE, the Cochrane library, and ISI Web of Science (until February 2013) for randomized trials comparing more than 12-month efficacy or safety of DES with BMS in patients with STEMI. Pooled estimate was presented with risk ratio (RR) and its 95% confidence interval (CI) using random-effects model. Results Ten trials with 7,592 participants with STEMI were included. The overall results showed that there was no significant difference in the incidence of all-cause death and definite/probable stent thrombosis between DES and BMS at long-term follow-up. Patients receiving DES implantation appeared to have a lower 1-year incidence of recurrent myocardial infarction than those receiving BMS (RR = 0.75, 95% CI 0.56 to 1.00, p= 0.05). Moreover, the risk of target vessel revascularization (TVR) after receiving DES was consistently lowered during long-term observation (all p< 0.01). In subgroup analysis, the use of everolimus-eluting stents (EES) was associated with reduced risk of stent thrombosis in STEMI patients (RR = 0.37, p=0.02). Conclusions DES did not increase the risk of stent thrombosis in patients with STEMI compared with BMS. Moreover, the use of DES did lower long-term risk of repeat revascularization and might decrease the occurrence of reinfarction. PMID:25004414

  9. Effects of plaque lengths on stent surface roughness.

    PubMed

    Syaifudin, Achmad; Takeda, Ryo; Sasaki, Katsuhiko

    2015-01-01

    The physical properties of the stent surface influence the effectiveness of vascular disease treatment after stent deployment. During the expanding process, the stent acquires high-level deformation that could alter either its microstructure or the magnitude of surface roughness. This paper constructed a finite element simulation to observe the changes in surface roughness during the stenting process. Structural transient dynamic analysis was performed using ANSYS, to identify the deformation after the stent is placed in a blood vessel. Two types of bare metal stents are studied: a Palmaz type and a Sinusoidal type. The relationship between plaque length and the changes in surface roughness was investigated by utilizing three different length of plaque; plaque length longer than the stent, shorter than the stent and the same length as the stent. In order to reduce computational time, 3D cyclical and translational symmetry was implemented into the FE model. The material models used was defined as a multilinear isotropic for stent and hyperelastic for the balloon, plaque and vessel wall. The correlation between the plastic deformation and the changes in surface roughness was obtained by intermittent pure tensile test using specimen whose chemical composition was similar to that of actual stent material. As the plastic strain is achieved from FE simulation, the surface roughness can be assessed thoroughly. The study found that the plaque size relative to stent length significantly influenced the critical changes in surface roughness. It was found that the length of stent which is equal to the plaque length was preferable due to the fact that it generated only moderate change in surface roughness. This effect was less influential to the Sinusoidal stent.

  10. Long-term outcomes of intravascular ultrasound-guided implantation of bare metal stents versus drug-eluting stents in primary percutaneous coronary intervention

    PubMed Central

    Cho, Yun-Kyeong; Park, Nam-Hee; Choi, Sang-Woong; Sohn, Ji-Hyun; Cho, Hyun-Ok; Park, Hyoung-Seob; Yoon, Hyuck-Jun; Kim, Hyungseop; Nam, Chang-Wook; Kim, Yoon-Nyun; Kim, Kwon-Bae

    2014-01-01

    Background/Aims While drug-eluting stents (DESs) have shown favorable outcomes in ST-segment elevation myocardial infarction (STEMI) compared to bare metal stents (BMSs), there are concerns about the risk of stent thrombosis (ST) with DESs. Because intravascular ultrasound (IVUS) guidance may help optimize stent placement and improve outcomes in percutaneous coronary intervention (PCI) patients, we evaluated the impact of IVUS-guided BMS versus DES implantation on long-term outcomes in primary PCI. Methods In all, 239 STEMI patients received DES (n = 172) or BMS (n = 67) under IVUS guidance in primary PCI. The 3-year incidence of major adverse cardiac events (MACEs) including death, myocardial infarction (MI), target vessel revascularization (TVR), and ST was evaluated. Results There was no difference in all cause mortality or MI. However, the incidence of TVR was 23.9% with BMS versus 9.3% with DES (p = 0.005). Thus, the number of MACEs was significantly lower with DES (11.0% vs. 29.9%; p = 0.001). The incidence of definite or probable ST was not different (1.5% vs. 2.3%; p = 1.0). IVUS-guided DES implantation (hazard ratio [HR], 0.25; 95% confidence interval [CI], 0.08 to 0.78; p = 0.017), stent length (HR, 1.03; 95% CI, 1.00 to 1.06; p = 0.046), and multivessel disease (HR, 3.01; 95% CI, 1.11 to 8.15; p = 0.030) were independent predictors of MACE. Conclusions In patients treated with primary PCI under IVUS guidance, the use of DES reduced the incidence of 3-year TVR versus BMS. However, all cause mortality and MI were similar between the groups. The incidence of ST was low in both groups. PMID:24574835

  11. Comparison of Clinical Outcomes in Patients Undergoing Coronary Intervention with Drug-Eluting Stents or Bare-Metal Stents: A Nationwide Population Study

    PubMed Central

    Sung, Shih-Hsien; Chen, Tzu-Ching; Cheng, Hao-Min; Lee, Jia-Chun; Lang, Hui-Chu; Chen, Chen-Huan

    2017-01-01

    Background The aim of this propensity score-matched cohort study was to investigate the prognostic impacts of drug-eluting stents (DES) and bare-metal stents (BMS) in patients undergoing percutaneous coronary intervention (PCI). Methods We conducted a retrospective cohort study based on the National Health Insurance program. Patients who had undergone coronary stenting between Jan. 2007 and Dec. 2008 were recruited and monitored until the end of 2010. Subjects with either BMS or DES were matched 2:1 by propensity score, which adjusted for age, sex, stent number and Charlson comorbidity index (CCI). The Kaplan-Meier method and Cox regression models were used for prognostic analyses. Results Among a total of 966 patients with a mean age of 66 years, 644 subjects had BMS and 322 subjects had DES. The incidence of myocardial infarction (MI) and death were significantly lower in the DES group as compared with the BMS group for the three-year follow-up duration. With adjustments for age, sex, premium-based monthly salary, levels of hospital care, stent number, CCI, medications, and acute coronary syndrome presentation in the index hospitalization, use of DES rather than BMS was associated with reduced adverse coronary events (hazard ratio and 95% confidence interval: 0.55, 0.38-0.81 in the whole population, and 0.44, 0.26-0.73 in the subgroup patients with stable coronary artery disease). Conclusions Implantation of DES was related to better outcomes than for BMS, in terms of reducing MI and mortality after PCI. The survival benefit for patients with DES was even greater in patients with stable coronary artery disease. PMID:28115802

  12. Coronary artery stent (image)

    MedlinePlus

    ... with a balloon catheter and expands when the balloon is inflated. The stent is then left there to help keep the artery open. ... with a balloon catheter and expands when the balloon is inflated. The stent is then left there to help keep the artery open.

  13. Usual Dose of Simvastatin Does Not Inhibit Plaque Progression and Lumen Loss at the Peri-Stent Reference Segments after Bare-Metal Stent Implantation: A Serial Intravascular Ultrasound Analysis

    PubMed Central

    Hong, Young Joon; Choi, Yun Ha; Ma, Eun Hye; Ko, Jum Suk; Lee, Min Goo; Park, Keun Ho; Sim, Doo Sun; Yoon, Nam Sik; Youn, Hyun Ju; Kim, Kye Hun; Park, Hyung Wook; Kim, Ju Han; Ahn, Youngkeun; Cho, Jeong Gwan; Park, Jong Chun; Kang, Jung Chaee

    2010-01-01

    Background/Aims The aim of this study was to assess the effects of a usual dose of simvastatin (20 mg/day) on plaque regression and vascular remodeling at the peri-stent reference segments after bare-metal stent implantation. Methods We retrospectively investigated serial intravascular ultrasound (IVUS) findings in 380 peri-stent reference segments (184 proximal and 196 distal to the stent) in 196 patients (simvastatin group, n = 132 vs. non-statin group, n = 64). Quantitative volumetric IVUS analysis was performed in 5-mm vessel segments proximal and distal to the stent. Results IVUS follow-up was performed at a mean of 9.4 months after stenting (range, 5 to 19 months). No significant differences were observed in the changes in mean plaque plus media (P&M) area, mean lumen area, and mean external elastic membrane (EEM) area from post-stenting to follow-up at both proximal and distal edges between the simvastatin and non-statin group. Although lumen loss within the first 3 mm from each stent edge was primarily due to an increase in P&M area rather than a change in EEM area, and lumen loss beyond 3 mm from each stent edge was due to a combination of increased P&M area and decreased EEM area, no significant differences in changes were observed in P&M, EEM, and lumen area at every 1-mm subsegment between the simvastatin and non-statin group. Conclusions A usual dose of simvastatin does not inhibit plaque progression and lumen loss and does not affect vascular remodeling in peri-stent reference segments in patients undergoing bare-metal stent implantation. PMID:21179272

  14. Impending rupture of saphenous vein graft aneurysm with floating fractured bare metal stent treated by coil embolization and covered stent implantation.

    PubMed

    Kodama, Atsuko; Kurita, Tairo; Kato, Osamu; Suzuki, Takahiko

    2016-11-01

    Aneurysmal degeneration of a saphenous vein graft (SVG) is a rare, but potentially fatal complication of coronary artery bypass graft (CABG) surgery. In this case report, a patient that had undergone prior CABG surgery and bare metal stent (BMS) implantation at the site of a stenotic SVG lesion presented at our hospital with chest pain, and an SVG aneurysm was detected at the previous BMS implantation site. In addition, the implanted BMS was fractured and floating in the SVG aneurysm. The SVG aneurysm was successfully occluded by percutaneous intervention, using a combination of distal covered stent deployment at the site of the anastomosis between the native coronary artery and the SVG and proximal coil embolization of the aneurysm.

  15. Common Iliac Artery Thrombosis following Pelvic Surgery Resulting in Kidney Allograft Failure Successfully Treated by Percutaneous Transluminal Angioplasty with Balloon-Expandable Covered Stent

    PubMed Central

    Golla, Maheswara S.; Acharjee, Subasit; Jaber, Bertrand L.; Garcia, Lawrence A.

    2015-01-01

    We report the case of a 66-year-old woman who developed acute kidney allograft failure due to thrombotic occlusion of the common iliac artery after hysterectomy requiring emergent allograft rescue. She underwent percutaneous transluminal angioplasty with endovascular balloon expandable covered stent graft placement in the right common iliac artery. Although there are a handful of case reports of acute limb ischemia secondary to acute common iliac artery thrombosis, this is the first case reported in the literature resulting in successful kidney allograft rescue following pelvic surgery. PMID:26355669

  16. On the role of SMA modeling in simulating NiTinol self-expanding stenting surgeries to assess the performance characteristics of mechanical and thermal activation schemes.

    PubMed

    Saleeb, A F; Dhakal, B; Owusu-Danquah, J S

    2015-09-01

    The work is focused on a detailed simulation of the key stages involved in the NiTinol self-expanding stenting surgical procedure; i.e., crimping, deployment, SMA activation, as well as post-surgery steady-state cyclic behavior mimicking the systolic-to-diastolic pressure oscillations. To this end, a general multi-mechanism SMA model was utilized, whose calibration was completed using the test data from simple isothermal uniaxial tension experiments. The emphasis in the study was placed on the comparison of two alternative SMA activation protocols, in terms of both the immediate and long-term (post-surgery) performance characteristics. The first is 'hard' mechanical activation utilizing superelasticity, and the second is 'soft' thermal activation relying upon the combined one-way shape memory effect and constrained-recovery characteristics of the NiTinol material. The important findings are (1) the thermal activation protocol is far superior compared to the mechanical counterpart, from the point of view of lower magnitudes of the induced outward chronic forces, lesser developed stresses in the host tissue, as well as higher compression ratio with lesser crimping force for the same geometry of initial stent memory configuration, (2) the thermal activation protocol completely bypassed the complications of maintaining the high restraining force during deployment of the stent, and (3) there is no indication of any detrimental functional fatigue/degradation in the cured stenotic artery during cyclic pressure oscillations.

  17. A new dextran-graft-polybutylmethacrylate copolymer coated on 316L metallic stents enhances endothelial cell coverage.

    PubMed

    Derkaoui, S M; Labbé, A; Chevallier, P; Holvoet, S; Roques, C; Avramoglou, T; Mantovani, D; Letourneur, D

    2012-09-01

    Amphiphilic copolymers based on the copolymerization of hydrophilic and hydrophobic moieties offer versatility in various biomedical material applications. Here, a new biocompatible copolymer of dextran-graft-polybutylmethacrylate is synthesized for the coating of metallic endovascular stents. Coating of metallic surfaces is performed and analyzed by X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, contact angle measurement, atomic force microscopy and scanning electron microscopy before and after deformation corresponding to stent deployment by a balloon catheter. In the conditions described here, the resulting coating is smooth and uniform with neither cracks nor detachment after stent expansion. Interestingly, surfaces coated with the copolymer greatly improve in vitro adhesion and growth of endothelial cells. This copolymer provides new opportunities for implanted biomaterials.

  18. Similar Success Rates with Bivalirudin and Unfractionated Heparin in Bare-Metal Stent Implantation

    SciTech Connect

    Hallak, Omar; Shams, S. Ali; Broce, Mike; Lavigne, P. Scott; Lucas, B. Daniel; Elhabyan, Abdul-Karim; Reyes, Bernardo J.

    2007-09-15

    Background. Unfractionated heparin (UFH) is the traditional agent utilized during percutaneous peripheral interventions (PPIs) despite its well-known limitations. Bivalirudin, a thrombin-specific anticoagulant, overcomes many of the limitations of UFH and has consistently demonstrated comparable efficacy with significantly fewer bleeding complications. The purpose of this study was to compare procedural success in patients undergoing bare-metal stent implantation for atherosclerotic blockage of the renal, iliac, and femoral arteries and receiving either bivalirudin (0.75 mg/kg bolus/1.75 mg/kg/hr infusion) or UFH (50-70 U/kg/hr bolus) as the primary anticoagulant. Methods. This study was an open-label, nonrandomized retrospective registry with the primary endpoint of procedural success. Secondary endpoints included incidence of: death, myocardial infarction (MI), urgent revascularization, amputation, and major and minor bleeding. Results. One hundred and five consecutive patients were enrolled (bivalirudin = 53; heparin = 52). Baseline demographics were comparable between groups. Patients were pretreated with clopidogrel (approx. 71%) and aspirin (approx. 79%). Procedural success was achieved in 97% and 96% of patients in the bivalirudin- and heparin-treated groups, respectively. Event rates were low and similar between groups. Conclusion. Bivalirudin maintained an equal rate of procedural success in this cohort without sacrificing patient safety. Results of this study add to the growing body of evidence supporting the safety and efficacy of bivalirudin as a possible substitute for UFH in anticoagulation during peripheral vascular bare-metal stent implantation.

  19. Follow-up Results of 71 Patients Undergoing Metallic Stent Placement for the Treatment of a Malignant Obstruction of the Superior Vena Cava

    SciTech Connect

    Nagata, Takeshi Makutani, Shiro; Uchida, Hideo; Kichikawa, Kimihiko; Maeda, Munehiro; Yoshioka, Tetsuya; Anai, Hiroshi; Sakaguchi, Hiroshi; Yoshimura, Hitoshi

    2007-09-15

    Purpose. To retrospectively clarify the utility of metallic stent placement for the treatment of the malignant obstruction of the superior vena cava (SVC) in 71 patients with VC syndrome (SVCS) on the basis of long-term follow-up data. Materials and Methods. Seventy-one patients underwent stent placement and were followed until death. The applicability of the spiral Z-stent (S-Z-stent) mainly used the initial and follow-up results, stent placement for bilateral BCV obstruction and the value of concurrent anticancer therapy were studied. Results. The technical success rate was 100%, the initial clinical success rate was 87% (62/71), the primary clinical patency rate was 88% (57/65), and the secondary clinical patency rate was 95% (62/65). The obstruction rate of the stent was 12% (8/65), and an additional stent was useful for relief of recurrent SVCS. Survival of 57 patients in whom there was no recurrence of SVCS until death ranged from 1 week to 29 months (mean, 5.4 months and the S-Z-stent appeared to be suitable for the treatment of the malignant obstruction of SVC. Unilateral stent placement was effective for relief of SVCS with bilateral BCV obstruction. Patients who received concurrent anticancer therapy survived 2 months longer than those who did not. Conclusion. Stent placement is an effective treatment for SVCS. Further, the utility of S-Z-stent for SVCS, an additional stent for recurrence, unilateral stent for patients with bilateral BCV obstruction, and anticancer therapy after stent placement were verified.

  20. The development of an in vitro test method for predicting the abrasion resistance of textile and metal components of endovascular stent grafts.

    PubMed

    Yao, Tong; Choules, Brian D; Rust, Jon P; King, Martin W

    2014-04-01

    Implantable endovascular stent grafts have become a frequent option for the treatment of abdominal and thoracic aneurysms. Given that such devices are permanent implants, the question of long-term biostability needs to be addressed. This article describes the development of an in vitro stent graft abrasion test method between the graft fabric and metal stent of an endovascular device. Three endpoints were established to determine the abrasion resistance between the fabric and stent surfaces after a predetermined number of abrasion cycles. During initial testing, two types of graft fabric materials, multifilament woven polyester fabric and monofilament woven polyester fabric, and two types of stent materials, laser cut nitinol stents and regular nitinol stent wire, were evaluated under dry and wet conditions. The results have shown that this test method is viable for testing the relative abrasion resistance of the components of endovascular stent grafts. The abrasion resistance of both fabrics was lower in a wet environment compared to being tested dry. Additionally, the multifilament polyester fabric had better abrasion resistance than the monofilament polyester fabric. The laser cut nitinol stent was more aggressive in creating holes and breaking yarns, while the regular nitinol stent wire caused a greater loss in fabric strength.

  1. Metallic stent insertion with double-balloon endoscopy for malignant afferent loop obstruction

    PubMed Central

    Fujii, Masakuni; Ishiyama, Shuhei; Saito, Hiroaki; Ito, Mamoru; Fujiwara, Akiko; Niguma, Takefumi; Yoshioka, Masao; Shiode, Junji

    2015-01-01

    Progress in double-balloon endoscopy (DBE) has allowed for the diagnosis and treatment of disease in the postoperative bowel. For example, a short DBE, which has a 2.8 mm working channel and 152 cm working length, is useful for endoscopic retrograde cholangiopancreatography in bowel disease patients. However, afferent loop and Roux-limb obstruction, though rare, is caused by postoperative recurrence of biliary tract cancer with intractable complications. Most of the clinical findings involving these complications are relatively nonspecific and include abdominal pain, nausea, vomiting, fever, and obstructive jaundice. Treatments by surgery, percutaneous transhepatic biliary drainage, percutaneous enteral stent insertion, and endoscopic therapy have been reported. The general conditions of patients with these complications are poor due to cancer progression; therefore, a less invasive treatment is better. We report on the usefulness of metallic stent insertion using an overtube for afferent loop and Roux-limb obstruction caused by postoperative recurrence of biliary tract cancer under short DBE in two patients with complexly reconstructed intestines. PMID:26078835

  2. Patency of paclitaxel-eluting versus bare metal stents long term after implantation in acute ST-segment elevation myocardial infarction.

    PubMed

    Vink, Maarten A; Van Nooijen, Ferdinand C; Laarman, Gerrit J; Suttorp, Maarten J; Tijssen, Jan G; Slagboom, Ton; Patterson, Mark S; Van Der Schaaf, Rene J; Kiemeneij, Ferdinand; Amoroso, Giovanni; Dirksen, Maurits T

    2011-11-01

    Drug-eluting stents effectively inhibit neointimal hyperplasia within the first year, thereby reducing the need for repeat revascularization. However, a delayed pattern of restenosis might be more prominent in drug-eluting stents compared to bare metal stents (BMSs). The extent of restenosis of paclitaxel-eluting stents (PESs) long term after implantation in acute ST-segment elevation myocardial infarction is currently unknown. The present study was designed to evaluate very late luminal loss (VLLL) of PESs used in ST-segment elevation myocardial infarction compared to BMSs. A total of 116 patients (61 with PESs and 55 with BMSs) initially included in the Paclitaxel Eluting Stent Versus Conventional Stent in ST-segment Elevation Myocardial Infarction (PASSION) trial and who were free from previous lesion failure underwent angiographic follow-up. Off-line quantitative coronary analysis of the angiogram immediately after stent implantation and at follow-up was performed. The primary end point was VLLL within the stent. The presence of binary restenosis was defined as diameter stenosis >50% as a secondary end point. The mean interval between stent implantation and follow-up was 4.1 ± 0.5 years in both stent groups. In-stent VLLL was 0.12 mm (interquartile range -0.03 to 0.42) in the PES group versus 0.30 mm (interquartile range 0.08 to 0.69) in the BMS group (p = 0.011). In-segment binary restenosis was found in 4 patients (6.6%) with a PES and 6 patients (10.9%) with a BMS (p = 0.40). In conclusion, angiographic follow-up 4 years after implantation in ST-segment elevation myocardial infarction showed that in patients prospectively randomized to PESs or BMSs, VLLL was low in both stent groups. PESs were associated with lower VLLL than BMSs, and the observed rate of binary restenosis was not significantly different between the 2 stent groups.

  3. Comparative study of the corrosion behavior of peripheral stents in an accelerated corrosion model: experimental in vitro study of 28 metallic vascular endoprostheses

    PubMed Central

    Paprottka, Karolin J.; Paprottka, Philipp M.; Reiser, Maximilian F.; Waggershauser, Tobias

    2015-01-01

    PURPOSE Clinical cases of stent-fractures show that corrosion behavior might play a role in these fractures. Implanted in vivo, especially in combination with other implanted foreign materials, these metallic products are exposed to special conditions, which can cause a process of corrosion. Here, we aimed to test the corrosion potential of stents made of different materials in an in vitro setting. METHODS A total of 28 peripheral stents of different materials (nitinol, cobalt-chromium-nickel, tantalum, V4A) and surface treatments (electropolish, mechanical polish, no polish) were tested in vitro. Corrosion was accelerated by applying a constant voltage of 3.5 V and amperage of 1.16 mA in 0.9% NaCl. RESULTS Nitinol stents showed the lowest susceptibility to corrosion and the longest period without damage. The Memotherm II® (BARD Angiomed®) was the only stent that showed neither macroscopic nor microscopic damages. The worst performing material was cobalt-chromium-nickel, which showed corrosion damages about ten times earlier compared to nitinol. Considering the reasons for termination of the test, nitinol stents primarily showed length deficits, while V4A and tantalum stents showed fractures. Cobalt-chromium-nickel stents had multiple fractures or a complete lysis in equal proportions. When placed in direct contact, nitinol stents showed best corrosion resistance, regardless of what material they were combined with. In terms of polishing treatments, electropolished stents performed the best, mechanical-polished stents and those without polishing treatment followed. CONCLUSION The analysis of corrosion behavior may be useful to select the right stent fulfilling the individual needs of the patient within a large number of different stents. PMID:26268301

  4. Gastric and Duodenal Stents: Follow-Up and Complications

    SciTech Connect

    Pinto Pabon, Isabel Teresa; Paul Diaz, Laura; Ruiz de Adana, Juan Carlos; Lopez Herrero, Julio

    2001-05-15

    Purpose: To assess the efficacy of self-expanding metallic stents in treating inoperable gastric and duodenal stenoses during follow-up and to evaluate the complications encountered.Methods: A total of 31 patients suffering from gastroduodenal obstruction (29 malignant, 2 benign) were treated with a self-expanding metallic stent (Wallstent). In 24 cases insertion was by the peroral route, in seven cases via gastrostomy.Results: All the strictures were successfully negotiated under fluoroscopic guidance without having to resort to endoscopy. A total of 27 patients (87%) were able to resume a regular diet, a soft diet, or a liquid diet orally. Complications included one case of stent malpositioning, one case of leakage of ascitic fluid through the gastrostomy orifice, one case of perforation and fistula to the biliary tree, and two cases of hematemesis. In two patients (6%) additional stents were implanted to improve patency. In all patients follow-up was maintained until death. Recurrence of symptoms immediately before death occurred in seven cases (23%). Mean survival time of patients was 13.3 weeks (SE {+-} 4.6).Conclusions: The deployment of gastroduodenal stents resulted in good palliation of inoperable gastric and duodenal stenoses. Certain technical aspects, e.g., adaptation of stents to bowel morphology, is critical to proper stent function and avoidance of complications.

  5. Palliative Airway Stenting Performed Under Radiological Guidance and Local Anesthesia

    SciTech Connect

    Profili, Stefano; Manca, Antonio; Feo, Claudio F. Padua, Guglielmo; Ortu, Riccardo; Canalis, Giulio C.; Meloni, Giovanni B.

    2007-02-15

    Purpose. To assess the effectiveness of airway stenting performed exclusively under radiological guidance for the palliation of malignant tracheobronchial strictures. Methods. We report our experience in 16 patients with malignant tracheobronchial stricture treated by insertion of 20 Ultraflex self-expandable metal stents performed under fluoroscopic guidance only. Three patients presented dysphagia grade IV due to esophageal malignant infiltration; they therefore underwent combined airway and esophageal stenting. All the procedures were performed under conscious sedation in the radiological room; average procedure time was around 10 min, but the airway impediment never lasted more than 40 sec. Results. We obtained an overall technical success in 16 cases (100%) and clinical success in 14 patients (88%). All prostheses were successfully placed without procedural complications. Rapid clinical improvement with symptom relief and normalization of respiratory function was obtained in 14 cases. Two patients died within 48 hr from causes unrelated to stent placement. Two cases (13%) of migration were observed; they were successfully treated with another stent. Tumor overgrowth developed in other 2 patients (13%); however, no further treatment was possible because of extensive laryngeal infiltration. Conclusions. Tracheobronchial recanalization with self-expandable metal stents is a safe and effective palliative treatment for malignant strictures. Airway stenting performed exclusively under fluoroscopic view was rapid and well tolerated.

  6. Biodegradable stents: they do their job and disappear.

    PubMed

    Waksman, Ron

    2006-02-01

    Despite the development and progression of metallic stents, many concerns still remain because of their permanent nature. Although metallic stents are effective in preventing recoil and late restenosis after coronary angioplasty, they continue to have limitations such as stent thrombosis and mismatch of the stent to the vessel size. Thus, the concept of bioabsorbable stents has emerged as an alternative to permanent metal stents. This review will outline concepts, material designs, preclinical, and initial clinical experimental studies with bioabsorbable stents.

  7. One year cost effectiveness of sirolimus eluting stents compared with bare metal stents in the treatment of single native de novo coronary lesions: an analysis from the RAVEL trial

    PubMed Central

    van Hout, B A; Serruys, P W; Lemos, P A; van den Brand, M J B M; Es, G-A van; Lindeboom, W K; Morice, M-C

    2005-01-01

    Objective: To assess the balance between costs and effects of the sirolimus eluting stent in the treatment of single native de novo coronary lesions in the RAVEL (randomised study with the sirolimus eluting Bx Velocity balloon expandable stent in the treatment of patients with de novo native coronary artery lesions) study. Design: Multicentre, double blind, randomised trial Setting: Percutaneous coronary intervention for single de novo coronary lesions Patients: 238 patients with stable or unstable angina. Interventions: Randomisation to sirolimus eluting stent or bare stent implantation. Main outcome measures: Patients were followed up to one year and the treatment effects were expressed as one year survival free of major adverse cardiac events (MACE). Costs were estimated as the product of resource utilisation and Dutch unit costs. Results: At one year, the absolute difference in MACE-free survival was 23% in favour of the sirolimus eluting stent group. At the index procedure, sirolimus eluting stent implantation had an estimated additional procedural cost of €1286. At one year, however, the estimated additional cost difference had decreased to €54 because of the reduction in the need for repeat revascularisations in the sirolimus group (0.8% v 23.6%; p < 0.01). After adjustment of actual results for the consequences of angiographic follow up (correction based on data from the BENESTENT (Belgium Netherlands stent) II study), the difference in MACE-free survival was estimated at 11.1% and the additional one year costs at €166. Conclusions: The one year data from RAVEL suggest an attractive balance between costs and effects for sirolimus eluting stents in the treatment of single native de novo coronary lesions. The cost effectiveness of drug eluting stents in more complex lesion subsets remains to be determined. PMID:15772214

  8. Stent intussusception after thromboaspiration through a platinum chrome stent: a particular case of longitudinal stent deformation.

    PubMed

    Mila, Rafael; Vignolo, Gustavo; Trujillo, Pedro

    2015-04-01

    The need to improve stent deliverability has led to the development of thinner and more flexible stents. However, there is concern about decreased longitudinal strength. The number of longitudinal stent deformation reports has dramatically increased. We report a case of stent longitudinal deformation after thromboaspiration through a new generation platinum chrome bare metal stent. Images show an "intussusception effect," an extreme form of the previously described "concertina deformation," as the mechanism of shortening. Since stent technology is constantly evolving, newer devices will probably be designed to have less susceptibility to longitudinal stent deformation.

  9. Stents and surgical interventions in the palliation of gastric outlet obstruction: a systematic review

    PubMed Central

    Minata, Mauricio Kazuyoshi; Bernardo, Wanderley Marques; Rocha, Rodrigo Silva de Paula; Morita, Flavio Hiroshi Ananias; Aquino, Julio Cesar Martins; Cheng, Spencer; Zilberstein, Bruno; Sakai, Paulo; de Moura, Eduardo Guimarães Hourneaux

    2016-01-01

    Background and study aims: Palliative treatment of gastric outlet obstruction can be done with surgical or endoscopic techniques. This systematic review aims to compare surgery and covered and uncovered stent treatments for gastric outlet obstruction (GOO). Patients and methods: Randomized clinical trials were identified in MEDLINE, Embase, Cochrane, LILACs, BVS, SCOPUS and CINAHL databases. Comparison of covered and uncovered stents included: technical success, clinical success, complications, obstruction, migration, bleeding, perforation, stent fracture and reintervention. The outcomes used to compare surgery and stents were technical success, complications, and reintervention. Patency rate could not be included because of lack of uniformity of the extracted data. Results: Eight studies were selected, 3 comparing surgery and stents and 5 comparing covered and uncovered stents.The meta-analysis of surgical and endoscopic stent treatment showed no difference in the technical success and overall number of complications. Stents had higher reintervention rates than surgery (RD: 0.26, 95 % CI [0.05, 0.47], NNH: 4). There is no significant difference in technical success, clinical success, complications, stent fractures, perforation, bleeding and the need for reintervention in the analyses of covered and uncovered stents. There is a higher migration rate in the covered stent therapy compared to uncovered self-expanding metallic stents (SEMS) in the palliation of malignant GOO (RD: 0.09, 95 % CI [0.04, 0.14], NNH: 11). Nevertheless, covered stents had lower obstruction rates (RD: – 0.21, 95 % CI [-0.27, – 0.15], NNT: 5). Conclusions: In the palliation of malignant GOO, covered SEMS had higher migration and lower obstruction rates when compared with uncovered stents. Surgery is associated with lower reintervention rates than stents. PMID:27857965

  10. Do metallic ports in tissue expanders affect postmastectomy radiation delivery?

    SciTech Connect

    Damast, Shari; Beal, Kathryn . E-mail: bealk@mskcc.org; Ballangrud, Ase; Losasso, Thomas J.; Cordeiro, Peter G.; Disa, Joseph J.; Hong, Linda; McCormick, Beryl L.

    2006-09-01

    Purpose: Postmastectomy radiation therapy (PMRT) is often delivered to patients with permanent breast implants. On occasion, patients are irradiated with a tissue expander (TE) in place before their permanent implant exchange. Because of concern of potential under-dosing in these patients, we examined the dosimetric effects of the Magna-Site (Santa Barbara, CA) metallic port that is present in certain TEs. Methods and Materials: We performed ex vivo film dosimetry with single 6-MV and 15-MV photon beams on a water phantom containing a Magna-Site disc in two orientations. Additionally, using in vivo films, we measured the exit dose from 1 patient's TE-reconstructed breast during chest wall treatment with 15-MV tangent beams. Finally, we placed thermoluminescent dosimeters (TLDs) on 6 patients with TEs who received PMRT delivered with 15-MV tangent beams. Results: Phantom film dosimetry revealed decreased transmission in the region of the Magna-Site, particularly with the magnet in the parallel orientation (at 22 mm: 78% transmission with 6 MV, 84% transmission with 15 MV). The transmission measured by in vivo films during single beam treatment concurred with ex vivo results. TLD data showed acceptable variation in median dose to the skin (86-101% prescription dose). Conclusion: Because of potential dosimetric effects of the Magna-Site, it is preferable to treat PMRT patients with permanent implants. However, it is not unreasonable to treat with a TE because the volume of tissue affected by attenuation from the Magna-Site is small. In this scenario, we recommend using 15 MV photons with compensating bolus.

  11. Colorectal Stents: Current Status

    PubMed Central

    Lee, Jeong-Mi

    2015-01-01

    A self-expandable metal stent (SEMS) is an effective and safe method for the decompression of colon obstruction. Based on recent evidence, colorectal SEMS is now recommended for the palliation of patients with colonic obstruction from incurable colorectal cancer or extracolonic malignancy and also as a bridge to surgery in those who are a high surgical risk. Prophylactic SEMS insertion in patients with no obstruction symptoms is not recommended. Most colorectal SEMS are inserted endoscopically under fluoroscopic guidance. The technical and clinical success rates of colorectal SEMS are high, and the complication rate is acceptable. Advances in this technology will make the insertion of colorectal SEMS better and may expand the indications of colorectal SEMS in the future. PMID:26064818

  12. 5 Years Experience With Drug Eluting and Bare Metal Stents as Primary Intervention in Transplant Renal Artery Stenosis

    PubMed Central

    Estrada, Chelsea C.; Musani, Muzammil; Darras, Frank; Suh, Heesuck; Abate, Mersema T.; Mani, Anil; Nord, Edward P.

    2017-01-01

    Background Transplant renal artery stenosis (TRAS) is a common vascular complication after kidney transplantation and is associated with refractory hypertension, volume overload, and graft injury or loss. This article describes 5-year outcomes of endovascular intervention for TRAS with bare metal and drug eluting stents (DES). Methods We investigated, as a prospective cohort study, patient and graft outcomes after the targeted use of DES for vessel diameter less than 5 mm and bare metal stents (BMS) for vessel diameter greater than 5 mm as the primary management for TRAS. Results From March 2008 to November 2014, 57 patients were stented for hemodynamically significant TRAS; 29 received DES, 26 received BMS, and 2 patients received both stent types. They were followed up for a mean of 35.1 ± 22.8 months; a subset of these patients who all received DES were followed up for 61.7 ± 17.5 months. Mean serum creatinine declined from 2.87 ± 1.5 mg/dL at the time of intervention to 1.98 ± 0.76 mg/dL (P < 0.001) at one month follow-up and was 1.96 ±0.92 mg/dL (P < 0.001) at 35.1 ± 22.8 months. Mean systolic blood pressure declined from 159.05 ± 19.68 mm Hg at time of intervention to 135.65 ± 15.10 mm Hg (P < 0.001) at most recent visit. Clinically driven restenosis requiring repeat revascularization occurred in 15.7% of patients. Conclusions Primary stenting with DES and BMS is both successful in the initial treatment of TRAS and also produced an immediate and long-term reduction in serum creatinine and systolic blood pressure. PMID:28361112

  13. Bioabsorbable metal stents for percutaneous treatment of critical recoarctation of the aorta in a newborn.

    PubMed

    Schranz, Dietmar; Zartner, Peter; Michel-Behnke, Ina; Akintürk, Hakan

    2006-05-01

    In neonates and infants with critical aortic coarctation, balloon angioplasty is considered for rescue therapy of heart failure. The use of conventional stents is limited because of further vessel growth, the need of redilation, and later surgical removal. However, a novel bioabsorbable magnesium stent (AMS) might overcome such restrictions of vessel stenting in newborns. Presented is the first use of an AMS for acute treatment of a newborn with severely impaired heart function due to a long segment recoarctation after a complex surgical repair. We hypothesize that bioabsorbable stents will dramatically change the treatment of coarctation and recoarctation in newborns.

  14. First biodegradable metal stent in a child with congenital heart disease: evaluation of macro and histopathology.

    PubMed

    Zartner, Peter; Buettner, Maike; Singer, Helmut; Sigler, Matthias

    2007-02-15

    New developments in stent technology led to the first biodegradable magnesium stents. To overcome the fundamental restrictions of conventional stent implantation, these new stents may improve interventional therapy, also in small children. What remains after complete degradation of a magnesium stent is of particular interest and concern. At the autopsy, 2 months after the projected complete degradation time of the 3.0 x 10 mm(2) stent, no solid compounds were detected, and the vessel diameter had increased slightly to 3.7 mm. Histological preparation revealed an amorphous to jelly-like substitute of the magnesium struts mainly consisting of calcium phosphate covered by fibrotic tissue. Immunological staining revealed no relevant inflammatory reaction to the stent material. Neointima proliferation was detected around the struts with some cellular infiltration of the calcium-phosphate material. These pathological and histological findings show minimal alteration of the vessel wall and an increase of the arterial diameter after stent degradation. This is an important precondition for further use of biodegradable stents in small infants. Further observations have to prove whether these findings do reproduce in other settings also.

  15. Effectiveness of Drug-Eluting Stents versus Bare-Metal Stents in Large Coronary Arteries in Patients with Acute Myocardial Infarction

    PubMed Central

    Sim, Doo Sun; Ahn, Youngkeun; Kim, Young Jo; Chae, Shung Chull; Hong, Taek Jong; Seong, In Whan; Chae, Jei Keon; Kim, Chong Jin; Cho, Myeong Chan; Seung, Ki Bae; Park, Seung Jung

    2011-01-01

    This study compared clinical outcomes of drug-eluting stents (DES) versus bare-metal stents (BMS) in large coronary arteries in patients with acute myocardial infarction (MI). A total of 985 patients who underwent single-vessel percutaneous coronary intervention (PCI) in large coronary arteries (≥ 3.5 mm) in lesions < 25 mm were divided into DES group (n = 841) and BMS group (n = 144). Clinical outcomes during 12 months were compared. In-hospital outcome was similar between the groups. At six months, death/MI rate was not different. However, DES group had significantly lower rates of target-lesion revascularization (TLR) (1.7% vs 5.6%, P = 0.021), target-vessel revascularization (TVR) (2.2% vs 5.6%, P = 0.032), and total major adverse cardiac events (MACE) (3.4% vs 11.9%, P = 0.025). At 12 months, the rates of TLR and TVR remained lower in the DES group (2.5% vs 5.9%, P = 0.032 and 5.9% vs 3.1%, P = 0.041), but the rates of death/MI and total MACE were not statistically different. The use of DES in large vessels in the setting of acute MI is associated with lower need for repeat revascularization compared to BMS without compromising the overall safety over the course of one-year follow-up. PMID:21468259

  16. Effect on Intimal Hyperplasia of Dexamethasone Released from Coated Metal Stents Compared with Non-Coated Stents in Canine Femoral Arteries

    SciTech Connect

    Strecker, Ernst-Peter; Gabelmann, Andreas; Boos, Irene; Lucas, Christopher; Xu, Zhongying; Haberstroh, Joerg; Freudenberg, Nicolaus; Stricker, Helmut; Langer, Mathias; Betz, Eberhard

    1998-11-15

    Purpose: Polymer-coated, dexamethasone (DXM)-releasing stents were tested in order to assess the efficacy of DXM released locally for the prevention of stent restenosis due to intimal hyperplasia. Methods: Strecker stents coated with a biodegradable membrane containing DXM were implanted percutaneously into the femoral artery in 14 dogs. The contralateral artery received a conventional non-coated stent serving as control. The drugs are eluted by degradation of the carrier membrane. Follow-up intraarterial digital subtraction angiography (DSA) was obtained at 3, 6, 9, 12, and 24 weeks with subsequent autopsy. Specimens for gross and microscopic pathology were obtained and histomorphometry was performed. Results: Four of 14 DXM-coated stents showed thrombotic occlusion within the first 3 weeks; ten DXM-coated stents remained patent. At follow-up DSA, DXM-coated stents showed a significantly wider lumen than the non-coated stents. At morphometry there was less intimal hyperplasia over DXM-coated stents than over non-coated stents (p < 0.05). Conclusion: DXM-coated stents reduce neointimal hyperplasia in dogs when compared with non-coated stents.

  17. Surgical failure after colonic stenting as a bridge to surgery

    PubMed Central

    Kim, Jung Ho; Kwon, Kwang An; Lee, Jong Joon; Lee, Won-Suk; Baek, Jeong-Heum; Kim, Yoon Jae; Chung, Jun-Won; Kim, Kyoung Oh; Park, Dong Kyun; Kim, Ju Hyun

    2014-01-01

    AIM: To identify risk factors for surgical failure after colonic stenting as a bridge to surgery in left-sided malignant colonic obstruction. METHODS: The medical records of patients who underwent stent insertion for malignant colonic obstruction between February 2004 and August 2012 were retrospectively reviewed. Patients with malignant colonic obstruction had overt clinical symptoms and signs of obstruction. Malignant colonic obstruction was diagnosed by computed tomography and colonoscopy. A total of 181 patients underwent stent insertion during the study period; of these, 68 consecutive patients were included in our study when they had undergone stent placement as a bridge to surgery in acute left-sided malignant colonic obstruction due to primary colon cancer. RESULTS: Out of 68 patients, forty-eight (70.6%) were male, and the mean age was 64.9 (range, 38-89) years. The technical and clinical success rates were 97.1% (66/68) and 88.2% (60/68), respectively. Overall, 85.3% (58/68) of patients underwent primary tumor resection and primary anastomosis. Surgically successful preoperative colonic stenting was achieved in 77.9% (53/68). The mean duration, defined as the time between the SEMS attempt and surgery, was 11.3 d (range, 0-26 d). The mean hospital stay after surgery was 12.5 d (range, 6-55 d). On multivariate analysis, the use of multiple self-expanding metal stents (OR = 28.872; 95%CI: 1.939-429.956, P = 0.015) was a significant independent risk factor for surgical failure of preoperative stenting as a bridge to surgery. Morbidity and mortality rates in surgery after stent insertion were 4.4% (3/68) and 1.5% (1/68), respectively. CONCLUSION: The use of multiple self-expanding metal stents appears to be a risk factor for surgical failure. PMID:25206288

  18. Heterogeneous Intravascular Ultrasound Findings of Stent Thrombosis

    PubMed Central

    Morofuji, Toru; Inaba, Shinji; Aisu, Hiroe; Takahashi, Kayo; Saito, Makoto; Higashi, Haruhiko; Yoshii, Toyofumi; Sumimoto, Takumi

    2017-01-01

    Objective The underlying mechanisms of stent thrombosis are not completely understood. Methods We experienced 12 definite stent thrombosis cases (1 early, 1 late, and 10 very late) at our hospital from July 2011 to April 2016 and evaluated the possible causes of stent thrombosis by intravascular ultrasound (IVUS). Results Five different potential morphological causes of stent thrombosis (neoatherosclerosis, stent malapposition, stent fracture, edge dissection, and stent underexpansion) were detected by IVUS in 10 cases (83.3%); in 1 of the remaining 2 cases, the discontinuation of antithrombotic drugs resulted in early stent thrombosis without abnormal IVUS findings. Of the 12 stent thrombosis cases, 4 occurred at a bare-metal stent (average time from stent implantation, 106 months); in all 12, significant neointimal hyperplasia was observed on IVUS, and 2 had plaque ruptures at an in-stent or proximal reference. Malapposed stent struts were observed in three very-late stent thromboses, and all of these underwent sirolimus-eluting stent implantation. Stent thrombosis due to mechanical (stent fracture) or procedure-related complications (edge dissection and stent underexpansion) was observed in three cases. Conclusion In patients with stent thrombosis, heterogeneous findings were observed in IVUS. This IVUS case series illustrates the possible mechanisms of stent thrombosis. PMID:28154268

  19. Acute Cholecystitis Caused by Malignant Cystic Duct Obstruction: Treatment with Metallic Stent Placement

    SciTech Connect

    Miyayama, Shiro Yamashiro, Masashi; Takeda, Taro; Aburano, Hiroyuki; Komatsu, Tetsuya; Sanada, Taku; Kosaka, Shotaro; Toya, Daisyu; Matsui, Osamu

    2008-07-15

    We report the successful management of acute cholecystitis using cystic duct stent placement in 3 patients with inoperable malignant cystic duct obstruction (2 cholangiocarcinoma and 1 pancreatic carcinoma). All patients underwent stent placement in the bile duct, using an uncovered stent in 2 and a covered stent in 1, to relieve jaundice occurring 8-184 days (mean 120 days) before the development of acute cholecystitis. The occluded cystic duct was traversed by a microcatheter and a stent was implanted 4-17 days (mean 12 days) after cholecystostomy. Acute cholecystitis was improved after the procedure in all patients. Two patients died 3 and 10 months later, while 1 has survived without cholecystitis for 22 months after the procedure to date.

  20. Randomised comparison of drug-eluting versus bare-metal stenting in patients with non-ST elevation myocardial infarction

    PubMed Central

    Remkes, Wouter S; Badings, Erik A; Hermanides, Renicus S; Rasoul, Saman; Dambrink, Jan-Henk E; Koopmans, Petra C; The, Salem HK; Ottervanger, Jan Paul; Gosselink, A T Marcel; Hoorntje, Jan CA; Suryapranata, Harry; van 't Hof, Arnoud WJ

    2016-01-01

    Objective The superiority of drug-eluting stents (DES) over bare-metal stents (BMS) in patients with ST elevation myocardial infarction (STEMI) is well studied; however, randomised data in patients with non-ST elevation myocardial infarction (NSTEMI) are lacking. The objective of this study was to investigate whether stenting with everolimus-eluting stents (EES) safely reduces restenosis in patients with NSTEMI as compared to BMS. Methods ELISA-3 patients were asked to participate in the angiographic substudy and were randomised to DE (Xience V) or BM (Vision) stenting (ELISA-3 group). The primary end point was minimal luminal diameter (MLD) at 9-month follow-up angiography. In addition, 296 patients with NSTEMI who were excluded or did not want to participate in the ELISA-3 trial (RELI group) were randomised to DE or BM stenting and underwent clinical follow-up only (major adverse cardiac events (MACE), stent thrombosis (ST)). A pooled analysis was performed to assess an effect on clinical outcome. Results 178 of 540 ELISA-3 patients participated in the angiographic substudy. MLD at 9 months angiography was 2.37±0.63 mm (DES) versus 1.84±0.62 mm (BMS), p<0.001. Binary restenosis occurred in 1.9% in the DES group versus 16.7% in the BMS group (RR 0.11, 95% CI 0.02 to 0.84, p=0.007). In the pooled analysis, the incidence of MACE, target vessel revascularisation and ST at 2 years follow-up in the DES versus BMS group was 12.5% versus 16.0% (p=0.28), 4.0% versus 10.4% (p=0.009) and 1.3% versus 3.0% (p=0.34), respectively. Conclusions In patients with NSTEMI, use of EES is safe and decreases both angiographic and clinical restenosis as compared to BMS http://www.isrctn.com/search?q=39230163. Trial registration number 39230163; Post-results. PMID:27933192

  1. Coronary Stent Infection Presented as Recurrent Stent Thrombosis

    PubMed Central

    Lai, Chih-Hung; Lin, Yung-Kai; Lee, Wen-Lieng

    2017-01-01

    Percutaneous transluminal coronary angioplasty with metal stent placement has become a well-developed treatment modality for coronary stenotic lesions. Although infection involving implanted stents is rare, it can, however, occur with high morbidity and mortality. We describe herein a case of an inserted coronary stent that was infected and complicated with recurrent stent thrombosis, pseudoaneurysm formation and severe sepsis. Despite repeated intervention and bypass surgery, the patient died from severe sepsis. PMID:28120580

  2. Sustained Benefit at 2 Years for Covered Stents Versus Bare-Metal Stents in Long SFA Lesions: The VIASTAR Trial

    SciTech Connect

    Lammer, Johannes E-mail: johannes.lammer@meduniwien.ac.at; Zeller, Thomas; Hausegger, Klaus A.; Schaefer, Philipp J.; Gschwendtner, Manfred; Mueller-Huelsbeck, Stefan; Rand, Thomas; Funovics, Martin Wolf, Florian; Rastan, Aljoscha; Gschwandtner, Michael; Puchner, Stefan; and others

    2015-02-15

    PurposeThe hypothesis that covered stents are superior to bare-metal stents (BMS) in long femoropopliteal artery disease was tested. The one-year results of the VIASTAR trial revealed a patency benefit of covered stents in the treatment-per-protocol (TPP) analysis only.MethodsA prospective, randomized, single-blind, multicenter study evaluated 141 patients with symptomatic peripheral arterial disease (PAD) after treatment with heparin-bonded covered stents (VIABAHN{sup ®} Endoprosthesis) or BMS. Clinical outcomes and patency rates were assessed at 1, 6, 12, and 24 months. Mean lesion length was 19.0 ± 6.3 cm in the VIABAHN{sup ®} versus 17.3 ± 6.6 cm in the BMS group.ResultsThe 24-month primary patency rates in the VIABAHN{sup ®} and BMS group were: intention-to-treat 63.1 (95 % CI 0.52–0.76) versus 41.2 % (95 % CI 0.29–0.57; log rank p = 0.04) and TPP 69.4 (95 % CI 0.58–0.83) versus 40.0 % (95 % CI 0.28–0.56; log rank p = 0.004). Freedom from target-lesion-revascularization (TLR) was 79.4 (95 % CI 0.70–0.90) versus 73.0 % (95 % CI 0.63–0.85) for VIABAHN{sup ®} versus BMS (log rank p = 0.37). For the TPP group in lesions ≥20 cm, the 24-month patency rates were 65.2 (95 % CI 0.50–0.85) versus 26.7 % (95 % CI 0.12–0.59; log rank p = 0.004) for VIABAHN{sup ®} versus BMS, and freedom from TLR was 80.0 (95 % CI 0.68–0.94) versus 61.9 % (95 % CI 0.44–0.87; log rank p = 0.13). The ankle brachial index was 0.89 ± 0.18 versus 0.91 ± 0.17 (p = 0.76) at 24-month in the VIABAHN{sup ®} versus the BMS group, respectively.ConclusionAt 24-month, this trial in PAD patients with long femoropopliteal lesions demonstrated a significantly improved primary patency rate for heparin-bonded covered stents compared to BMS, however, without a significant impact on clinical outcomes and TLR rate (Reg. Nr. ISRCTN48164244)

  3. Malignant Gastroduodenal Obstruction: Treatment with Self-Expanding Uncovered Wallstent

    SciTech Connect

    Gutzeit, Andreas Binkert, Christoph A.; Schoch, Eric; Sautter, Thomas; Jost, Res; Zollikofer, Christoph L.

    2009-01-15

    Purpose: To retrospectively evaluate the clinical effectiveness of a self-expanding uncovered Wallstent in patients with malignant gastroduodenal obstruction. Materials and Methods: Under combined endoscopic and fluoroscopic guidance, 29 patients with a malignant gastroduodenal stenosis were treated with a self-expanding uncovered metallic Wallstent. A dysphagia score was assessed before and after the intervention to measure the success of this palliative therapy. The dysphagia score ranged between grade 0 to grade 4: grade 0 = able to tolerate solid food, grade 1 = able to tolerate soft food, grade 2 = able to tolerate thick liquids, grade 3 = able to tolerate water or clear fluids, and grade 4 = unable to tolerate anything perorally. Stent patency and patients survival rates were calculated. Results: The insertion of the gastroduodenal stent was technically successful in 28 patients (96.5%). After stenting, 25 patients (86.2%) showed clinical improvement by at least one score point. During follow-up, 22 (78.5%) of 28 patients showed no stent occlusion until death and did not have to undergo any further intervention. In six patients (20.6%), all of whom were treated with secondary stent insertions, occlusion with tumor ingrowth and/or overgrowth was observed after the intervention. The median period of primary stent patency in our study was 240 days. Conclusion: Placement of an uncovered Wallstent is clinically effective in patients with malignant gastroduodenal obstruction. Stent placement is associated with high technical success, good palliation effect, and high durability of stent function.

  4. Evidence-Based Recommendations on Upper Gastrointestinal Tract Stenting: A Report from the Stent Study Group of the Korean Society of Gastrointestinal Endoscopy

    PubMed Central

    Jee, Sam Ryong; Kim, Kyung Ho; Kim, Sang Gyun; Cho, Jun-Hyung

    2013-01-01

    Endoscopic stents have evolved dramatically over the past 20 years. With the introduction of uncovered self-expanding metal stents in the early 1990s, they are primarily used to palliate symptoms of malignant obstruction in patients with inoperable gastrointestinal (GI) cancer. At present, stents have emerged as an effective, safe, and less invasive alternative for the treatment of malignant GI obstruction. Clinical decisions about stent placement should be made based on the exact understanding of the patient's condition. These recommendations based on a critical review of the available data and expert consensus are made for the purpose of providing endoscopists with information about stent placement. These can be helpful for management of patients with inoperable cancer or various nonmalignant conditions in the upper GI tract. PMID:23964331

  5. Network meta-analysis of balloon angioplasty, nondrug metal stent, drug-eluting balloon, and drug-eluting stent for treatment of infrapopliteal artery occlusive disease

    PubMed Central

    Xiao, Yaowen; Chen, Zhong; Yang, Yaoguo; Kou, Lei

    2016-01-01

    PURPOSE We aimed to conduct a network meta-analysis of mixed treatments for the infrapopliteal artery occlusive disease. METHODS We searched randomized controlled trials (RCTs) regarding balloon angioplasty (BA), nondrug metal stent (NDMS), drug-eluting balloon (DEB), or drug-eluting stent (DES) in PubMed, Embase, CENTRAL, Ovid, Sinomed, and other relevant websites. We selected and assessed the trials that met the inclusion criteria and conducted a network meta-analysis using the ADDIS software. RESULTS We included 11 relevant trials. We analyzed data of 1322 patients with infrapopliteal artery occlusive disease, of which 351 were in the NDMS vs. DES trials, 231 in the NDMS vs. BA trials, 490 in the BA vs. DEB trials, 50 in the DEB vs. DES trials, and 200 in the BA vs. DES trials. The network meta-analysis indicated that with NDMS as the reference, DES had a better result with respect to restenosis (odds ratio [OR], 5.16; 95% credible interval [CI], 1.58–18.41; probability of the best treatment, 84%) and amputation (OR, 2.50; 95% CI, 0.81–7.11; probability of the best treatment, 61%) and DEB had a better result with respect to target lesion revascularization (TLR; OR, 3.74; 95% CI, 0.78–17.05; probability of the best treatment, 57%). Moreover, with BA as the reference, NDMS had a better result with respect to technical success (OR, 0.10; 95% CI, 0.00–1.15; probability of the best treatment, 86%). CONCLUSION Our meta-analysis revealed that DES is a better treatment with respect to short-term patency and limb salvage rate, NMDS may provide a better technical success, and DEB and DES are good choices for reducing revascularization. PMID:27559766

  6. Intimal hyperplasia following implantation of helical-centreline and straight-centreline stents in common carotid arteries in healthy pigs: influence of intraluminal flow†

    PubMed Central

    Caro, Colin Gerald; Seneviratne, Anusha; Heraty, Kevin B.; Monaco, Claudia; Burke, Martin G.; Krams, Rob; Chang, Carlos C.; Coppola, Gianfilippo; Gilson, Paul

    2013-01-01

    Intimal hyperplasia (IH) is a leading cause of obstruction of vascular interventions, including arterial stents, bypass grafts and arteriovenous grafts and fistulae. Proposals to account for arterial stent-associated IH include wall damage, low wall shear stress (WSS), disturbed flow and, although not widely recognized, wall hypoxia. The common non-planarity of arterial geometry and flow, led us to develop a bare-metal, nitinol, self-expanding stent with three-dimensional helical-centreline geometry. This was deployed in one common carotid artery of healthy pigs, with a straight-centreline, but otherwise identical (conventional) stent deployed contralaterally. Both stent types deformed the arteries, but the helical-centreline device additionally deformed them helically and caused swirling of intraluminal flow. At sacrifice, one month post stent deployment, histology revealed significantly less IH in the helical-centreline than straight-centreline stented vessels. Medial cross-sectional area was not significantly different in helical-centreline than straight-centreline stented vessels. By contrast, luminal cross-sectional area was significantly larger in helical-centreline than straight-centreline stented vessels. Mechanisms considered to account for those results include enhanced intraluminal WSS and enhanced intraluminal blood–vessel wall mass transport, including of oxygen, in the helical-centreline stented vessels. Consistent with the latter proposal, adventitial microvessel density was lower in the helical-centreline stented than straight-centreline stented vessels. PMID:24132200

  7. Development of a New Hanging-Type Esophageal Stent for Preventing Migration: A Preliminary Study in an Animal Model of Esophagotracheal Fistula

    SciTech Connect

    Endo, Masayuki Kaminou, Toshio Ohuchi, Yasufumi; Sugiura, Kimihiko; Yata, Shinsaku Adachi, Akira Kawai, Tsuyoshi Takasugi, Syohei Yamamoto, Shuichi Matsumoto, Kensuke; Hashimoto, Masayuki; Ihaya, Takashi; Ogawa, Toshihide

    2012-10-15

    Purpose: Covered, self-expandable metallic stents (SEMS) have been enthusiastically adopted for the treatment of esophagotracheal fistula, but problems with stent migration have yet to be resolved. To overcome this problem, we have developed a new hanging-type esophageal stent designed to prevent migration, and we conducted an animal study to assess the efficacy of our method. Methods: A total of six female pigs were used in this study. The main characteristic of our stent was the presence of a string tied to the proximal edge of the stent for fixation under the skin of the neck. The first experiment was performed to confirm technical feasibility in three pigs with esophagotracheal fistula. The second experiment was performed to evaluate stent migration and esophagotracheal fistula in three pigs. Results: Creation of the esophagotracheal fistula and stent placement were technically successful in all pigs. In the first experiment, esophagotracheal fistula was sealed by stent placement. In the second experiment, no stent migration was seen 11 or 12 days after stent placement. Gross findings showed no fistulas on the esophageal or tracheal wall. Conclusions: Our new hanging-type esophageal stent seems to offer a feasible method for preventing stent migration.

  8. The location of obstruction predicts stent occlusion in malignant gastric outlet obstruction

    PubMed Central

    Grunwald, Douglas; Cohen, Jonah; Bartley, Anthony; Sheridan, Jennifer; Chuttani, Ram; Sawhney, Mandeep S.; Pleskow, Douglas K.; Berzin, Tyler M.; Mizrahi, Meir

    2016-01-01

    Background: Gastric outlet obstruction (GOO) can occur with locally invasive or metastatic cancer involving the upper gastrointestinal tract at the pylorus or the duodenum. Endoscopic management with self-expanding metal stents (SEMSs) is often the preferred palliative approach. Stent occlusion is a common reason for failure and reintervention. We set out to determine whether the location of the malignant obstruction is associated with the angulation of the stent and can predict stent occlusion. Methods: We performed a retrospective review of consecutive patients who underwent successful duodenal stenting with SEMS for malignant GOO between 2006 and 2015 at a large advanced endoscopy referral center. We determined the location of obstruction, the stent angle, and the rate of technical and clinical success of stent placement. We then identified cases of subsequent stent occlusion confirmed by endoscopic evaluation. Results: A total of 100 consecutive patients were included in the study; 91 of these patients had enough data to evaluate SEMS occlusion. A total of 21 patients (23%) developed stent occlusion with a median time of 39 days. The risk of occlusion sequentially increased as the obstruction occurred more distally from the antrum to the third or fourth portion of the duodenum (p = 0.006). This relationship was maintained after controlling for stent angle (p = 0.05). Conclusions: A distal location of malignant GOO was strongly predictive of stent occlusion, independent of stent angle. This may be due to longer and more complex distal obstructions, along with foreshortening of the stent during placement and tumor infiltration. If replicated, these results will have implications for endoscopic practice and future device development. PMID:27803736

  9. Drug-Eluting Stents: Do They Increase Heart Attack Risk?

    MedlinePlus

    ... intervention, or PCI). Drug-eluting stents have a polymer coating over mesh that emits a drug over ... 2014. Bangalore S, et al. Bare metal stents, durable polymer drug eluting stents, and biodegradable polymer drug eluting ...

  10. Hematopoietic Stem Cell Capture and Directional Differentiation into Vascular Endothelial Cells for Metal Stent-Coated Chitosan/Hyaluronic Acid Loading CD133 Antibody

    PubMed Central

    Zhang, Fan; Feng, Bo; Fan, Qingyu; Yang, Feng; Shang, Debin; Sui, Jinghan; Zhao, Hong

    2015-01-01

    A series of metal stents coated with chitosan/hyaluronic acid (CS/HA) loading antibodies by electrostatic self-assembled method were prepared, and the types of cells captured by antibodies and their differentiation in vascular endothelial cells (ECs) evaluated by molecular biology and scanning electron microscope. The results showed that CD133 stent can selectively capture hematopoietic stem cells (HSC),which directionally differentiate into vascular ECs in peripheral blood by (CS/HA) induction, and simultaneously inhibit migration and proliferation of immune cells and vascular smooth muscle cells (MCs). CD34 stent can capture HSC, hematopoietic progenitor cells that differentiate into vascular ECs and immune cells, promoting smooth MCs growth, leading to thrombosis, inflammation, and rejection. CD133 stent can be implanted into miniature pig heart coronary and can repair vascular damage by capturing own HSC, thus contributing to the rapid natural vascular repair, avoiding inflammation and rejection, thrombosis and restenosis. These studies demonstrated that CD133 stent of HSC capture will be an ideal coated metal stent providing a new therapeutic approach for cardiovascular and cerebrovascular disease. PMID:25404533

  11. Safety and Efficacy of Biodegradable Drug-Eluting vs. Bare Metal Stents: A Meta-Analysis from Randomized Trials

    PubMed Central

    Zhao, Xiaohui

    2014-01-01

    Background Biodegradable polymeric coatings have been proposed as a promising strategy to enhance biocompatibility and improve the delayed healing in the vessel. However, the efficacy and safety of biodegradable polymer drug-eluting stents (BP-DES) vs. bare metal stents (BMS) are unknown. The aim of this study was to perform a meta-analysis of randomized controlled trials (RCTs) comparing the outcomes of BP-DES vs. BMS. Methods and Results PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for randomized clinical trials, until December 2013, that compared any of approved BP-DES and BMS. Efficacy endpoints were target-vessel revascularization (TVR), target-lesion revascularization (TLR) and in-stent late loss (ISLL). Safety endpoints were death, myocardial infarction (MI), definite stent thrombosis (DST). The meta-analysis included 7 RCTs with 2,409 patients. As compared with BMS, there was a significantly reduced TVR (OR [95% CI] = 0.37 [0.28–0.50]), ISLL (OR [95% CI] = −0.41 [−0.48–0.34]) and TLR (OR [95% CI] = 0.38 [0.27–0.52]) in BP-DES patients. However, there were no difference for safety outcomes between BP-DES and BMS. Conclusions BP-DES is more effective in reducing ISLL, TVR and TLR, as safe as standard BMS with regard to death, ST and MI. Further large RCTs with long-term follow-up are warranted to better define the relative merits of BP-DES. PMID:24945816

  12. Drug-coated balloon in combination with bare metal stent strategy for de novo coronary artery disease

    PubMed Central

    Lu, Wenjie; Zhu, Yongjian; Han, Zhanying; Wang, Xi; Wang, Xule; Qiu, Chunguang

    2017-01-01

    Abstract Background: Studies examining the efficiency of drug-coated balloon (DCB) + bare metal stent (BMS) compared with stents alone for de novo lesions have reported inconsistent results. The present comprehensive meta-analysis of randomized controlled trials (RCTs) assessed and compared the clinical efficacy and safety of DCB + BMS with those of stents alone for de novo coronary artery disease. Methods: We formally searched electronic databases before September 2016 to identify potential studies. All RCTs were eligible for inclusion if they compared DCB + BMS with a control treatment (drug-eluting stent [DES] alone or BMS alone) in patients with de novo coronary artery disease. Results: Eleven RCTs with a total of 2196 patients met the inclusion criteria were included in our meta-analysis. Subgroup analysis indicated DCB plus BMS was associated with poorer outcomes when compared with DES alone in primary endpoint {(in-segment late lumen loss [LLL]: mean difference [MD], 0.19; 95% confidence interval [CI], 0.06–0.32; P = 0.0042) and (major adverse cardiovascular events [MACEs]: risk ratio [RR], 1.88; 95% CI, 1.44–2.45; P < 0.0001)}. However, DCB + BMS had nonsignificantly lower LLL than BMS alone (in-segment LLL: MD, −0.14; 95% CI, −0.33–0.04; P = 0.24), and was more advantageous in reducing MACE incidence, with borderline significance (MACEs: RR, 0.67; 95% CI, 0.45–0.99; P = 0.05). Conclusions: In summary, the present results do not favor the DCB + BMS strategy as an alternative therapeutic method to DES implantation for de novo coronary artery lesions in percutaneous coronary intervention (PCI). Additional well-designed large RCTs with long-follow-up periods are required to clarify the inconsistent results. PMID:28328833

  13. Analysis of risk factors associated with complications of colonic stenting for malignant obstruction.

    PubMed

    Dindar, Gokhan; Ustundag, Yucel; Karakan, Tarkan

    2014-07-21

    Self expanding metalic stent (SEMS) application can cause serious problems up to one third of the patients and some studies reported negative effect of SEMSs on survival in patients with malignancy. The SEMS type especially the rigid one like Wall-stent rather than more flexible type Ultraflex was also reported to have bad impact on the risk of perforation we believe that stent based management protocol for patients with non-perforating left sided obstructing colorectal cancer is a complex method that needs qualified medical and technical team.

  14. Analysis of risk factors associated with complications of colonic stenting for malignant obstruction

    PubMed Central

    Dindar, Gokhan; Ustundag, Yucel; Karakan, Tarkan

    2014-01-01

    Self expanding metalic stent (SEMS) application can cause serious problems up to one third of the patients and some studies reported negative effect of SEMSs on survival in patients with malignancy. The SEMS type especially the rigid one like Wall-stent rather than more flexible type Ultraflex was also reported to have bad impact on the risk of perforation we believe that stent based management protocol for patients with non-perforating left sided obstructing colorectal cancer is a complex method that needs qualified medical and technical team. PMID:25083098

  15. Erosion of esophageal stent into left main bronchus causing airway compromise

    PubMed Central

    Aneeshkumar, S; Sundararajan, L; Santosham, Rajan; Palaniappan, Rajkumar; Dhus, Ubal

    2017-01-01

    Covered or uncovered self-expanding metal stents are currently used for the palliative treatment of neoplastic esophageal strictures or compressions and esophageal leaks or fistulas due to malignancies. Erosion of esophageal stents into the respiratory tract is a rare complication and that too has been reported mostly as an early complication within few days or weeks. Here, we present the case of a 31-year-old female, who presented with a late complication of an esophageal stent eroding into the left main bronchus causing respiratory distress. She was stented for a benign corrosive esophageal stricture following caustic soda ingestion 3 years ago. She underwent a thoracotomy and closure of esophagobronchial fistula along with laparoscopic esophagectomy and gastric pull through. Postoperatively, patient developed an anastomotic leak which was corrected by placing a temporary stent. PMID:28144066

  16. Plastic biliary stents for malignant biliary diseases.

    PubMed

    Huibregtse, Inge; Fockens, Paul

    2011-07-01

    Plastic biliary endoprostheses have not changed much since their introduction more than 3 decades ago. Although their use has been challenged by the introduction of metal stents, plastic stents still remain commonly used. Much work has been done to improve the problem of stent obstruction but without substantial clinical success. In this review, the authors discuss the history of plastic biliary stent development and the current use of plastic stents for malignant biliary diseases.

  17. AMS INSIGHT--absorbable metal stent implantation for treatment of below-the-knee critical limb ischemia: 6-month analysis.

    PubMed

    Bosiers, Marc; Peeters, Patrick; D'Archambeau, Olivier; Hendriks, Jeroen; Pilger, Ernst; Düber, Christoph; Zeller, Thomas; Gussmann, Andreas; Lohle, Paul N M; Minar, Erich; Scheinert, Dierk; Hausegger, Klaus; Schulte, Karl-Ludwig; Verbist, Jürgen; Deloose, Koen; Lammer, J

    2009-05-01

    Endoluminal treatment of infrapopliteal artery lesions is a matter of controversy. Bioabsorbable stents are discussed as a means to combine mechanical prevention of vessel recoil with the advantages of long-term perspectives. The possibility of not having a permanent metallic implant could permit the occurrence of positive remodeling with lumen enlargement to compensate for the development of new lesions. The present study was designed to investigate the safety of absorbable metal stents (AMSs) in the infrapopliteal arteries based on 1- and 6-month clinical follow-up and efficacy based on 6-month angiographic patency. One hundred seventeen patients with 149 lesions with chronic limb ischemia (CLI) were randomized to implantation of an AMS (60 patients, 74 lesions) or stand-alone percutaneous transluminal angioplasty (PTA; 57 patients, 75 lesions). Seven PTA-group patients "crossed over" to AMS stenting. The study population consisted of patients with symptomatic CLI (Rutherford categories 4 and 5) and de novo stenotic (>50%) or occlusive atherosclerotic disease of the infrapopliteal arteries who presented with a reference diameter of between 3.0 and 3.5 mm and a lesion length of <15 mm. The primary safety endpoint was defined as absence of major amputation and/or death within 30 days after index intervention and the primary efficacy endpoint was the 6-month angiographic patency rate as confirmed by core-lab quantitative vessel analysis. The 30-day complication rate was 5.3% (3/57) and 5.0% (3/60) in patients randomized for PTA alone and PTA followed by AMS implantation, respectively. On an intention-to-treat basis, the 6-month angiographic patency rate for lesions treated with AMS (31.8%) was significantly lower (p = 0.013) than the rate for those treated with PTA (58.0%). Although the present study indicates that the AMS technology can be safely applied, it did not demonstrate efficacy in long-term patency over standard PTA in the infrapopliteal vessels.

  18. Double stenting for malignant oesophago-respiratory fistula

    PubMed Central

    Kużdżał, Jarosław

    2016-01-01

    Introduction The close anatomical relationship between the oesophagus and bronchial tree results in formation of an oesophago-respiratory fistula in a subset of patients with advanced oesophageal or lung cancer. In those patients stenting of both the oesophagus and tracheobronchial tree is a valid option of palliative treatment. Aim To determine the effectiveness, tolerance, quality of life, safety and survival after double stenting procedures. Material and methods Retrospective analysis of a prospectively collected database was performed, concerning consecutive patients with oesophago-respiratory fistulas treated with double stenting. In all patients the degree of dysphagia, respiratory function before and after the procedure, and quality of life were evaluated. Partially covered oesophageal self-expanding metallic stents (PCESEMS) were used for oesophageal stenting, and silicone Y-type or partially covered self-expanding bronchial and tracheal stents (PCASEMS) were used to restore airway patency. Results Between 2003 and 2015, 31 patients underwent double stenting due to oesophago-respiratory fistulas. Twenty-nine patients were diagnosed with oesophageal squamous cell carcinoma and 2 with bronchial carcinoma. In all patients, improvement in the general condition and quality of life was observed after airway patency restoration. Two patients required mechanical ventilation due to respiratory failure immediately after the procedure. Seven patients with oesophageal fistulas died because of bleeding in the long-term follow-up. Four patients required endoscopic re-intervention. Mean survival time was 67.1 days. Conclusions Double stenting is an effective procedure improving patients’ quality of life. However, life-threatening complications can occur. PMID:27829946

  19. Expanding iClick to group 9 metals

    DOE PAGES

    Beto, Christopher C.; Yang, Xi; Powers, Andrew R.; ...

    2015-09-01

    In this study, the iClick (inorganic click) reactions between gold-acetylides and group 9 transition metal-azide complexes are presented. Complexes [Rh(CO)(PPh3)2][PPh3Au](μ-N3C2C6H4NO2) (3), {[Rh(CO)(PPh3)][PPh3Au](μ-N3C2C6H4NO2)}2 (4), and [(CO)(PPh3)2IrAuPPh3](μ-N3C2C6H4NO2) (6) have been synthesized via M-azide/M-acetylide cycloaddition reactions between PPh3Au(Ctriple bond; length of mdashCC6H4NO2) (2) and either Rh(CO)(PPh3)2N3 (1), or Ir(CO)(PPh3)2N3 (5). Complexes 3, 4, and 6 have been characterized by a combination of NMR spectroscopies, crystallography and combustion analysis.

  20. Expanding iClick to group 9 metals

    SciTech Connect

    Beto, Christopher C.; Yang, Xi; Powers, Andrew R.; Ghiviriga, Ion; Abboud, Khalil A.; Veige, Adam S.

    2015-09-01

    In this study, the iClick (inorganic click) reactions between gold-acetylides and group 9 transition metal-azide complexes are presented. Complexes [Rh(CO)(PPh3)2][PPh3Au](μ-N3C2C6H4NO2) (3), {[Rh(CO)(PPh3)][PPh3Au](μ-N3C2C6H4NO2)}2 (4), and [(CO)(PPh3)2IrAuPPh3](μ-N3C2C6H4NO2) (6) have been synthesized via M-azide/M-acetylide cycloaddition reactions between PPh3Au(Ctriple bond; length of mdashCC6H4NO2) (2) and either Rh(CO)(PPh3)2N3 (1), or Ir(CO)(PPh3)2N3 (5). Complexes 3, 4, and 6 have been characterized by a combination of NMR spectroscopies, crystallography and combustion analysis.

  1. Materials and Manufacturing Technologies Available for Production of a Pediatric Bioabsorbable Stent

    PubMed Central

    Alexy, Ryan D.; Levi, Daniel S.

    2013-01-01

    Transcatheter treatment of children with congenital heart disease such as coarctation of the aorta and pulmonary artery stenosis currently involves the use of metal stents. While these provide good short term results, there are long term complications with their use. Children outgrow metal stents, obligating them to future transcatheter dilations and eventual surgical removal. A bioabsorbable stent, or a stent that goes away with time, would solve this problem. Bioabsorbable stents are being developed for use in coronary arteries, however these are too small for use in pediatric congenital heart disease. A bioabsorbable stent for use in pediatric congenital heart disease needs to be low profile, expandable to a diameter 8 mm, provide sufficient radial strength, and absorb quickly enough to allow vessel growth. Development of absorbable coronary stents has led to a great understanding of the available production techniques and materials such as bioabsorbable polymers and biocorrodable metals. Children with congenital heart disease will hopefully soon benefit from the current generation of bioabsorbable and biocorrodable materials and devices. PMID:24089660

  2. Self-expanding plastic esophageal stents versus jejunostomy tubes for the maintenance of nutrition during neoadjuvant chemoradiation therapy in patients with esophageal cancer: a retrospective study.

    PubMed

    Siddiqui, A A; Glynn, C; Loren, D; Kowalski, T

    2009-01-01

    In patients undergoing chemoradiotherapy for esophageal cancer, the inability to eat may severely impair nutritional status. We conducted a retrospective study to compare the efficacy of the Polyflex self-expanding silicone stent (PS) versus a jejunostomy tube (JT) for maintaining nutrition during neoadjuvant chemoradiation therapy in patients with esophageal cancer who were scheduled for resectional surgery. Thirty-six patients were treated either with PS placement (12 patients) or JT placement (24 patients) prior to receiving an 8-week course of chemoradiation therapy. Patients were interviewed weekly until cessation of therapy. Patient data were collected on procedural success and complication rates, nutritional status, and dysphagia scores. PS placement was successful in 11 of 12 patients (92%), and those 11 patients were able to resume oral nutrition. Dysphagia scores improved from a mean of 3 to 1 in the PS group (P < 0.005) but did not change significantly in the JT group. PS were removed endoscopically without complications prior to the esophagectomies. Albumin levels and weight increased significantly in both the PS and JT groups. There were no significant differences between groups in the procedural success rates (PS 92% vs. JT 100%, P = 0.33), complication rates (PS 22% vs. JT 4%, P = 0.11), mean increase in weight (PS 4.4 kg vs. JT 4.2 kg, P = 0.59), and mean increase in serum albumin (PS 0.62 g/dL vs. JT 0.44 g/dL, P = 0.05). PS is a safe and effective alternative to a surgical JT for maintaining nutrition in this subset of patients.

  3. 76 FR 67793 - Notification of Expanded Pricing Grid for Precious Metals Products Containing Platinum and Gold...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-02

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF THE TREASURY United States Mint Notification of Expanded Pricing Grid for Precious Metals Products Containing Platinum and Gold--Excluding Commemorative Gold Coins AGENCY: United States Mint, Department of the...

  4. A case of ampullary perforation treated with a temporally covered metal stent.

    PubMed

    Park, Woo Young; Cho, Kwang Bum; Kim, Eun Soo; Park, Kyung Sik

    2012-06-01

    Endoscopic retrograde cholangiopancreatography (ERCP)-related perforation is classified into three or four types based on anatomical location and the mechanism of injury. Although ampullary injury, among them, may be managed nonsurgically, surgical management is required in cases of perforation with retroperitoneal fluid collection and severe condition. Here, a patient with ERCP-related severe ampullary perforation with retroperitoneal fluid collection that was treated nonsurgically with a covered stent is presented.

  5. Fabrication and characterization of metal stent coating with drug-loaded nanofiber film for gallstone dissolution.

    PubMed

    Gao, Qiang; Huang, Chao; Sun, Binbin; Aqeel, Bhutto M; Wang, Jing; Chen, Weiming; Mo, Xiumei; Wan, Xinjian

    2016-11-01

    Stent insertion and chemical agents of ethylene diamine tetraacetic acid and sodium cholate for dissolving common bile duct stone diseases through extra biliary tract infusion have been believed a relatively effective therapeutics for the clinical symptom. Core-shell nanofibers produced by co-axial electrospinning to deliver chemical drugs, biomacromolecules, genes and even cells have been reported for various advanced drug delivery system and tissue engineering applications. In the present study, poly (lactide-co-ɛ-caprolactone) (PLCL) core-shell nanofiber-coated film of stent, loaded with ethylene diamine tetraacetic acid and sodium cholate in core layer, was fabricated by co-axial electrospinning for treating gallstone disease. Image of laser scanning confocal microscopy and transmission electron microscopy demonstrated core-shell structure of drug-loaded nanofiber. Fourier transform infrared spectra and the thermogravimetric analysis proved ethylene diamine tetraacetic acid and sodium cholate to be successfully loaded in nanofibers. Morphology of nanofibers after a period of degradation still keeps good shape. Drugs can continuously release for around five days, which was proved significant effectiveness for dissolving gallstone. Besides, unobvious cytotoxicity was exhibited from MTT results and cell kept good morphology in vitro research. The present coated stent showed a bright prospect for dissolving the biliary stone.

  6. Stent Angioplasty of Closed Mesocaval Shunt in a Patient with Budd-Chiari Syndrome

    SciTech Connect

    Sancak, Tanzer; Karagulle, Ayse Tuba; Bilgic, Sadik; Sanlidilek, Umman; Yerdel, Mehmet Ali

    2002-08-15

    Budd-Chiari syndrome (BCS) is an uncommon disorder caused by hepatic venous outflow obstruction. It is characterized by ascites, hepatomegaly and abdominal pain. Percutaneous intervention shave recently been used for the treatment of BCS. We present a case of BCS with a closed mesocaval shunt which was reopened with a self-expandable metallic stent.

  7. Bone Marrow Nails Created by Percutaneous Osteoplasty for Long Bone Fracture: Comparisons Among Acrylic Cement Alone, Acrylic-Cement-Filled Bare Metallic Stent, and Acrylic-Cement-Filled Covered Metallic Stent

    SciTech Connect

    Nakata, Kouhei; Kawai, Nobuyuki; Sato, Morio Cao, Guang; Sahara, Shinya; Sonomura, Tetsuo; Takasaka, Isao; Minamiguchi, Hiroki; Nakai, Motoki

    2011-06-15

    Purpose: This study was designed to compare the strength among bone marrow nails created to treat long bone fractures using interventional procedures. Methods: Twelve resected intact tibiae of healthy swine were used. A circumferential bone fracture was made in nine tibiae and restored with the following created bone marrow nails: acrylic cement alone (ACA) (n = 3), acrylic-cement-filled bare metallic stent (AC-FBMS) (n = 3), and acrylic-cement-filled covered metallic (AC-FCMS) stent (n = 3). The remaining intact tibiae (n = 3) were used as controls. Results: A bone marrow nail was successfully achieved within 30 min in all swine. The maximum injection volume of acrylic cement for creating ACA, AC-FBMS, and AC-FCMS was 1.7 {+-} 0.3, 3.2 {+-} 0.4, and 2.9 {+-} 0.4 mL, respectively. The thickness of bone marrow nail created in the ACA, AC-FBMS, and AC-FCMS groups was 3.6 {+-} 1.0, 10.3 {+-} 0.26, and 9.6 {+-} 0.32 mm, respectively (AC-FBMS group versus AC-FCMS group, p = 0.038), probably because of leakage of acrylic cement surrounding the interstices. The maximum bending power (kilonewton) and bending strength (newton/mm{sup 2}) in the normal long bone, ACA, AC-FBMS, and AC-FCMS groups were: 1.70 {+-} 0.25 and 79.2 {+-} 16.1; 0.21 {+-} 0.11 and 8.8 {+-} 2.8; 0.46 {+-} 0.06 and 18.2 {+-} 1.6; and 0.18 {+-} 0.04 and 7.8 {+-} 2.7, respectively. Conclusions: Although the maximum bending power and bending strength of AC-FBMS were not satisfactory, it was the most robust of the three marrow nails for restoring fractured long bone.

  8. Stop adding metal layers: Will bioabsorbable scaffolds become the gold standard for late in-stent restenosis and neo-atherosclerosis?

    PubMed

    Kilic, Ismail Dogu; Konstantinidis, Nikolaos; Pighi, Michele; Mattesini, Alessio; Di Mario, Carlo

    2015-03-01

    The optimal management of instent restenosis has yet to be fully clarified. Drug eluting balloons are a popular strategy, but a new stent is preferred when dilatation gives a suboptimal result because of insufficient extrusion of neointimal tissue. There is concern for adding multiple permanent metallic layers to the vessel wall, especially in small vessels. The use of bioabsorbable vascular scaffolds appears an appealing alternative strategy, since it scaffolds the neointimal tissue without further adding metal struts to the vessel wall.

  9. MR safety and imaging of neuroform stents at 3T.

    PubMed

    Nehra, Arvind; Moran, Christopher J; Cross, Dewitte T; Derdeyn, Colin P

    2004-10-01

    The Neuroform stent is a self-expanding nitinol stent designed for use in wide-necked intracranial aneurysms. Heating and imaging artifacts were evaluated by using a porcine carotid artery aneurysm model in a 3T MR system. A suspended Neuroform stent was tested for deflection. No heating was measured, and no evidence of deflection of the stent was found. Imaging artifacts were minimal. MR imaging in patients with Neuroform stent-treated aneurysms is safe and feasible.

  10. Mechanical behavior of peripheral stents and stent-vessel interaction: A computational study

    NASA Astrophysics Data System (ADS)

    Dottori, Serena; Flamini, Vittoria; Vairo, Giuseppe

    2016-05-01

    In this paper stents employed to treat peripheral artery disease are analyzed through a three-dimensional finite-element approach, based on a large-strain and large-displacement formulation. Aiming to evaluate the influence of some stent design parameters on stent mechanics and on the biomechanical interaction between stent and arterial wall, quasi-static and dynamic numerical analyses are carried out by referring to computational models of commercially and noncommercially available versions of both braided self-expandable stents and balloon-expandable stents. Addressing isolated device models, opening mechanisms and flexibility of both opened and closed stent configurations are numerically experienced. Moreover, stent deployment into a stenotic peripheral artery and possible postdilatation angioplasty (the latter for the self-expandable device only) are simulated by considering different idealized vessel geometries and accounting for the presence of a stenotic plaque. Proposed results highlight important differences in the mechanical response of the two types of stents, as well as a significant influence of the vessel shape on the stress distributions arising upon the artery-plaque system. Finally, computational results are used to assess both the stent mechanical performance and the effectiveness of the stenting treatment, allowing also to identify possible critical conditions affecting the risk of stent fracture, tissue damage, and/or pathological tissue response.

  11. Endoscopic esophageal self-expanding stent implantation WallFlex™ (Boston Scientific) in the management of a gastrocutaneous fistula, as a complication of sleeve bariatric gastrectomy.

    PubMed

    Janczak, Dariusz; Pawłowski, Wiktor; Ziomek, Agnieszka; Dorobisz, Tadeusz; Janczak, Dawid; Janus, Werner; Chabowski, Mariusz

    2015-06-01

    The study presented a case of a gastrocutaneous fistula, as a result of bariatric sleeve gastrectomy. The discussion considered the main pathogenesis, etiology, diagnostics and endoscopic treatment using the implantation of covered esophageal stents. Special attention was placed upon the multifactorial origin of this life-threatening clinical condition, typical for bariatric surgery.

  12. Endoscopic ultrasonography-guided placement of a transhepatic portal vein stent in a live porcine model

    PubMed Central

    Park, Tae Young; Seo, Dong Wan; Kang, Hyeon-Ji; Cho, Min Keun; Song, Tae Jun; Park, Do Hyun; Lee, Sang Soo; Lee, Sung Koo; Kim, Myung-Hwan

    2016-01-01

    Background and Objectives: Percutaneous portal vein (PV) stent placement is used to manage PV occlusion or stenosis caused by malignancy. The use of endoscopic ultrasonography (EUS) has expanded to include vascular interventions. The aim of this study was to examine the technical feasibility and safety of EUS-guided transhepatic PV stent placement in a live porcine model. Materials and Methods: EUS-guided transhepatic PV stent placement was performed in six male miniature pigs under general anesthesia using forward-viewing echoendoscope. Under EUS guidance, the left intrahepatic PV was punctured with a 19-gauge fine-needle aspiration (FNA) needle and a 0.025 inch guidewire inserted through the needle and into the main PV. The FNA needle was then withdrawn and a needle-knife inserted to dilate the tract. Under EUS and fluoroscopic guidance, a noncovered metal stent was inserted over the guidewire and released into the main PV. Results: A PV stent was placed successfully in all six pigs with no technical problems or complications. The patency of the stent in the main PV was confirmed using color Doppler EUS and transhepatic portal venography. Necropsy of the first three animals revealed no evidence of bleeding and damage to intra-abdominal organs or vessels. No complications occurred in the remaining three animals during the 8 weeks observation period. Conclusions: EUS-guided transhepatic PV stent placement can be both technically feasible and safe in a live animal model. PMID:27803904

  13. The immobilization of recombinant human tropoelastin on metals using a plasma-activated coating to improve the biocompatibility of coronary stents.

    PubMed

    Waterhouse, Anna; Yin, Yongbai; Wise, Steven G; Bax, Daniel V; McKenzie, David R; Bilek, Marcela M M; Weiss, Anthony S; Ng, Martin K C

    2010-11-01

    Current endovascular stents have sub-optimal biocompatibility reducing their clinical efficacy. We previously demonstrated a plasma-activated coating (PAC) that covalently bound recombinant human tropoelastin (TE), a major regulator of vascular cells in vivo, to enhance endothelial cell interactions. We sought to develop this coating to enhance its mechanical properties and hemocompatibility for application onto coronary stents. The plasma vapor composition was altered by incorporating argon, nitrogen, hydrogen or oxygen to modulate coating properties. Coatings were characterized for 1) surface properties, 2) mechanical durability, 3) covalent protein binding, 4) endothelial cell interactions and 5) thrombogenicity. The N(2)/Ar PAC had optimal mechanical properties and did not delaminate after stent expansion. The N(2)/Ar PAC was mildly hydrophilic and covalently bound the highest proportion of TE, which enhanced endothelial cell proliferation. Acute thrombogenicity was assessed in a modified Chandler loop using human blood. Strikingly, the N(2)/Ar PAC alone reduced thrombus weight by ten-fold compared to 316L SS, a finding unaltered with immobilized TE. Serum soluble P-selectin was reduced on N(2)/Ar PAC and N(2)/Ar PAC + TE (p < 0.05), consistent with reduced platelet activation. We have demonstrated a coating for metal alloys with multifaceted biocompatibility that resists delamination and is non-thrombogenic, with implications for improving coronary stent efficacy.

  14. Cocaine-induced very late stent thrombosis.

    PubMed

    Shah, Priyank; Vasudev, Rahul; Abuarqoub, Ahmad Hisham; Shamoon, Fayez

    2016-10-12

    Cocaine misuse is a known cause of acute coronary syndrome (ACS). Management of these patients has always been a challenge due to medication compliance and eventual risk of stent thrombosis. However, even cocaine misusers who are compliant with dual antiplatelet therapy have been reported to have stent thrombosis. All cases of cocaine-induced stent thrombosis reported in the literature have occurred within first year of stent placement (acute, subacute or late). We report a first case of very late stent thrombosis in a 54-year-old active cocaine misuser who presented with ST segment elevation myocardial infarction, which was successfully managed with percutaneous transluminal coronary angioplasty. A review of all the reported cases of cocaine-induced stent thrombosis is also discussed. Given the high mortality associated with stent thrombosis, treatment option for cocaine misusers presenting with ACS should be conservative when possible. If percutaneous coronary intervention is needed, bare metal stent should be preferred.

  15. Complete Obliteration of a Basilar Artery Aneurysm after Insertion of a Self-Expandable Leo Stent into the Basilar Artery without Coil Embolization

    PubMed Central

    Nowak, Stanisław; Wieloch, Michał; Zarzecka, Anna

    2008-01-01

    We report a case of a 45-year-old man who underwent endovascular treatment in the acute setting of a subarachnoid hemorrhage due to rupture of a wide-necked basilar trunk aneurysm. The patient was treated with stent implantation without coiling. A control angiographic scan obtained immediately after the procedure revealed significantly decreased intraaneurysmal flow. Follow-up angiography performed after one month demonstrated total aneurysm occlusion. PMID:18682676

  16. Complete obliteration of a basilar artery aneurysm after insertion of a self-expandable Leo stent into the basilar artery without coil embolization.

    PubMed

    Juszkat, Robert; Nowak, Stanisław; Wieloch, Michał; Zarzecka, Anna

    2008-01-01

    We report a case of a 45-year-old man who underwent endovascular treatment in the acute setting of a subarachnoid hemorrhage due to rupture of a wide-necked basilar trunk aneurysm. The patient was treated with stent implantation without coiling. A control angiographic scan obtained immediately after the procedure revealed significantly decreased intraaneurysmal flow. Follow-up angiography performed after one month demonstrated total aneurysm occlusion.

  17. Prognostic value of inflammation-based markers in patients with recurrent malignant obstructive jaundice treated by reimplantation of biliary metal stents

    PubMed Central

    Jin, Hao; Pang, Qing; Liu, Huichun; Li, Zongkuang; Wang, Yong; Lu, Yimin; Zhou, Lei; Pan, Hongtao; Huang, Wei

    2017-01-01

    Abstract We aimed to assess the therapeutic effect of reimplantation of biliary metal stents by percutaneous transhepatic cholangial drainage (PTCD) in patients with recurrent malignant obstructive jaundice (MOJ). Furthermore, we explored the prognostic value of inflammation-based markers in these patients. We reviewed 33 cases of recurrent MOJ after implantation of biliary metal stents by PTCD, all of which underwent reimplantation of stents under digital subtraction angiography guidance. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and bilirubin were compared between before and after reimplantation (1 week, 1 month, and 3 months postoperatively). Preoperative clinical data were collected to calculate the inflammation-based markers, including systemic immune-inflammation index (SII, neutrophil × platelets/ lymphocyte), platelets-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and monocyte-to-lymphocyte ratio (MLR). The primary outcome was overall survival (OS), which was estimated by the Kaplan–Meier method and Cox regression analysis. The levels of ALT, AST, total bilirubin, and direct bilirubin significantly reduced after the reimplantation operation. During a median follow-up time of 10 months, 18 (54.5%) patients died. Gender, albumin, SII, PLR, NLR, and MLR were found to be associated with OS by the log-rank test and univariate analysis. Multivariate Cox analysis identified elevated levels of SII and PLR as significant factors for predicting poor OS. Reimplantation is clinically feasible in patients with recurrent MOJ after implantation of biliary metal stents. SII and PLR are independent, useful inflammation-based prognostic models for predicting outcomes in these patients. PMID:28099348

  18. Formation of bound states in expanded metal studied via path integral molecular dynamics

    NASA Astrophysics Data System (ADS)

    Deymier, P. A.; Oh, Ki-Dong

    2004-03-01

    The usefulness of the restricted path integral molecular dynamics method for the study of strongly correlated electrons is demonstrated by studying the formation of bound electronic states in a half-filled expanded three-dimensional hydrogenoid body-centred cubic lattice at finite temperature. Starting from a metallic state with one-component plasma character, we find that bound electrons form upon expansion of the lattice. The bound electrons are spatially localized with their centre for the motion of gyration located at ionic positions. The number of bound electrons increases monotonically with decreasing density.

  19. Comparison of frequency of major adverse events in patients with atrial fibrillation receiving bare-metal versus drug-eluting stents in their coronary arteries.

    PubMed

    Fauchier, Laurent; Pellegrin, Céline; Bernard, Anne; Clementy, Nicolas; Angoulvant, Denis; Lip, Gregory Y H; Babuty, Dominique

    2012-07-01

    In patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention with drug-eluting stent (DES) implantation, the available evidence from clinical trial data are inconclusive. We evaluated the safety and efficacy of the use of DESs versus bare-metal stents (BMSs) in a consecutive real-world cohort of patients with AF. Of 8,962 unselected patients with AF seen in our institution from 2000 through 2010, 833 (9%) had undergone percutaneous coronary intervention with stent implantation. BMSs were used for 678 patients (81%) and DESs for 155 (19%). During follow-up (median 688 days, interquartile range 1,114), all bleeding episodes, thromboembolism, and major adverse cardiac events (MACEs; i.e., death, acute myocardial infarction, target lesion revascularization) were recorded. Incidence of MACEs was similar in the 2 groups as was incidence of all-cause mortality. Results remained similar even after adjustment for age and other confounding factors. Factors independently associated with an increased risk of MACEs were older age (hazard ratio 1.024, 95% confidence interval 1.004 to 1.044, p = 0.02), implantation of stent during acute ST-segment elevation myocardial infarction (hazard ratio 1.81, 95% confidence interval 1.10 to 2.99, p = 0.02), and stent diameter (hazard ratio 1.09, 95% confidence interval 1.01 to 1.18, p = 0.03). Implantation of DESs was not significantly associated with a higher risk of major bleeding and we observed a similar ratio of serious events at follow-up after DES compared to BMS implantation. In conclusion, in our cohort, systematic use of DESs does not seem to be justified in most patients with AF because it was not associated with any clear advantage compared to BMSs.

  20. Transient Hemolytic Anemia after Transjugular Intrahepatic Portosystemic Stent Shunt

    PubMed Central

    Garcia-Rebollo, Sagrario; Santolaria-Fernández, Francisco; Diaz-Romero, Francisco; Rodriguez-Moreno, Fermin; Martinez-Riera, Antonio

    1996-01-01

    Management of variceal bleeding secondary to portal hypertension constitutes a challenging issue, particularly in child's C cirrhotic patients. Recently, transjugular placement of self-expanding metallic stents in the liver (TIPS), creating a shunt between the portal and hepatic branches has provided a safe and promising therapeutic approach in this clinical situation. We report here the case of a 66-year-old male cirrhotic patient who developed a moderately severe clinical picture of a Coombsnegative hemolytic anemia (serum hemoglobin, 93 g/l, serum bilirubin 160.74 umol/L (9.4 mg/dl), indirect 6.3 mg/dl (107.73 umol/L); serum LDH 1220 u/l, reticulocytes, 5.1%. serum ferritin, 1221 ug/1, schistocytes in peripheral blood smear) the week after undergoing a TIPS, suggesting the development ofa microangiopathic hemolytic anaemia secondary to red blood cell disruption by passing through the metallic network of the stent. PMID:8809588

  1. First successful implantation of a biodegradable metal stent into the left pulmonary artery of a preterm baby.

    PubMed

    Zartner, Peter; Cesnjevar, Robert; Singer, Helmut; Weyand, Michael

    2005-12-01

    Stent implantation in the youngest patients with a congenital heart disease implicates limitations concerning further vessel growth, the need of staged redilation, and later surgical removal. The search to overcome these restrictions led to open stent designs, with a wide adaptability to the vessel growth and recently to the development of bioabsorbable stent materials. A preterm baby born at 26 weeks of gestation was referred to our clinic following inadvertent ligation of the left pulmonary artery. Despite efficient debanding, the left lung perfusion was absent. Implantation of a biodegradable 3 mm magnesium stent was performed in a hybrid procedure when the baby weighed 1.7 kg. Reperfusion of the left lung was established and persisted throughout the 4-month follow-up period during which the gradual degradation process of the stent completed. Additional interventions, should they become necessary, seem not to be limited. Despite the small size of the baby, the degradation process was clinically well tolerated. The mechanical and degradation characteristics of the magnesium stent proved to be adequate to secure reperfusion of the previously occluded left pulmonary artery. Bioabsorbable stents with different diameters may help develop new strategies in the therapy of vessel stenosis in pediatric patients.

  2. A simple technique to remove migrated esophageal stents.

    PubMed

    Noyer, C M; Forohar, F

    1998-09-01

    A 51-yr-old man with a tracheoesophageal fistula from an esophageal carcinoma had two expandable covered stents placed, which migrated distally. After several unsuccessful attempts to remove the stents, we fashioned a homemade snare to entrap and remove the stents under endoscopic and fluoroscopic guidance.

  3. The use of flow diverter stents in the management of traumatic vertebral artery dissections.

    PubMed

    Cohen, José E; Gomori, John M; Moscovici, Samuel; Bala, Miklosh; Itshayek, Eyal

    2013-05-01

    Flow diverters constitute a new generation of flexible self-expanding stent-like devices with a high metal-surface area coverage, specifically designed for the endovascular management of complex cerebral aneurysms. Recently, other potential applications for these devices in the field of occlusive cerebrovascular disease have been described. In vertebral artery dissections causing occlusion associated with a burden of extensive clots, we have found that the reduced porosity of the diverter mesh serves as an effective barrier to in-stent clot protrusion and distal embolization. We describe the novel use of a flow diverter for the management of an occlusive traumatic vertebral artery dissection. Diverter implantation allowed subsequent angioplasty.

  4. Emerging Stent and Balloon Technologies in the Femoropopliteal Arteries

    PubMed Central

    Pastromas, Georgios; Katsanos, Konstantinos; Krokidis, Miltiadis; Karnabatidis, Dimitrios

    2014-01-01

    Endovascular procedures for the management of the superficial femoral (SFA) and popliteal artery disease are increasingly common. Over the past decade, several stent technologies have been established which may offer new options for improved clinical outcomes. This paper reviews the current evidence for SFA and popliteal artery angioplasty and stenting, with a focus on randomized trials and registries of nitinol self-expanding stents, drug-eluting stents, dug-coated balloons, and covered stent-grafts. We also highlight the limitations of the currently available data and the future routes in peripheral arterial disease (PAD) stent and balloon technology. PMID:24672355

  5. Late Stent Expansion and Neointimal Proliferation of Oversized Nitinol Stents in Peripheral Arteries

    SciTech Connect

    Zhao, Hugh Q. Nikanorov, Alexander; Virmani, Renu; Jones, Russell; Pacheco, Erica; Schwartz, Lewis B.

    2009-07-15

    For peripheral endovascular intervention, self-expanding (SE) stents are commonly oversized in relation to target arteries to assure optimal wall apposition and prevent migration. However, the consequences of oversizing have not been well studied. The purpose of this study was to examine the effects of SE stent oversizing (OS) with respect to the kinetics of late stent expansion and the long-term histological effects of OS. Pairs of overlapped 8 x 28-mm Nitinol SE stents were implanted into the iliofemoral arteries of 14 Yucatan swine. Due to variations in target artery size, the stent-to-artery ratio ranged from 1.2:1 to 1.9:1. Lumen and stent diameters were assessed by quantitative angiography at the time of implantation. Following angiographic assessment at 6 months, stented arteries were perfusion-fixed, sectioned, and stained for histological analysis. Immediately following implantation, the stents were found to be expanded to a range of 4.7-7.1 mm, largely conforming to the diameter of the recipient target artery. The stents continued to expand over time, however, and all stents had enlarged to nearly their 8-mm nominal diameter by 6 months. The histological effects of OS were profound, with marked increases in injury and luminal area stenosis, including a statistically significant linear correlation between stent-to-artery ratio and area stenosis. In this experimental model of peripheral endovascular intervention, oversized Nitinol SE stents are constrained by their target artery diameter upon implantation but expand to their nominal diameter within 6 months. Severe OS (stent-to-artery ratio >1.4:1) results in a profound long-term histological response including exuberant neointimal proliferation and luminal stenosis.

  6. Stents in patients with esophageal cancer before chemoradiotherapy: high risk of complications and no impact on the nutritional status.

    PubMed

    Mão-de-Ferro, S; Serrano, M; Ferreira, S; Rosa, I; Lage, P; Alexandre, D P; Freire, J; Mirones, L; Casaca, R; Bettencourt, A; Pereira, A D

    2016-03-01

    Preoperative chemoradiotherapy is the standard of care for locally advanced esophageal cancer, causing persistent deterioration in the nutritional status. We performed a prospective study to evaluate the safety and efficacy of esophageal double-covered self-expandable metal stents in patients with esophageal cancer before chemoradiotherapy. The nutritional status and dysphagia were prospectively recorded. Eleven patients were included: eight were moderate and three were severely malnourished. After stent placement, dysphagia improved in all patients. With regard to complications, one patient developed an esophageal perforation that required urgent esophagectomy. Four patients presented stent migration. Three of these patients required enteral nutrition and none was submitted to surgery because of poor nutritional status. Of the other six patients, only four were operated upon. Stent placement presented a high complication rate and did not prevent weight loss or malnutrition. Other alternatives, including naso-gastric tube placement or endoscopic percutaneous gastrostomy or jejunostomy, should be considered.

  7. Stent-based percutaneous coronary interventions in small coronary arteries.

    PubMed

    Roguin, Ariel; Grenadier, Ehud

    2006-01-01

    A third to half of all percutaneous coronary interventions involve small diameter vessels of less than 3 mm. Small vessel size is a predictor of restenosis after balloon angioplasty, as well as after stent placement. Stents deployed in small arteries, have a higher metal-to-artery ratio; this may increase the risk of sub-acute thrombosis or restenosis. Various studies have shown that stent design, stent coating, and stent strut thickness may determine event-free survival. Dedicated stents for small vessels with less amount of metal, appropriate expansion to the vessel size with correct radial force and cells morphology, and less prothrombotic properties, may further improve the results of stenting in this setting (thinner struts, fewer cells, or loops per circumference). This review provides an update on the current status, review the major trials and define the clinical utility of small vessel stenting, particularly in the era of drug-eluting stents.

  8. Clinical Outcomes in Diabetic Patients Who Underwent Percutaneous Coronary Intervention during the Plain Old Balloon Angioplasty (POBA)-, Bare Metal Stents (BMS)- and Drug-eluting Stents (DES)-eras from 1984 to 2010

    PubMed Central

    Naito, Ryo; Miyauchi, Katsumi; Konishi, Hirokazu; Tsuboi, Shuta; Ogita, Manabu; Dohi, Tomotaka; Kasai, Takatoshi; Tamura, Hiroshi; Okazaki, Shinya; Isoda, Kikuo; Daida, Hiroyuki

    2017-01-01

    Objective Diabetes is a negative predictor in coronary artery disease patients. Since the introduction of percutaneous coronary intervention (PCI), PCI has evolved through technological advances in devices, improvements in operators' techniques and the establishment of effective therapeutic protocols. The aim of this study is to examine the changes in the clinical outcomes following PCI in patients with diabetes. Methods We compared the clinical outcomes in patients with diabetes following PCI from 1984 to 2010 at Juntendo University over three eras (plain old balloon angioplasty (POBA)-, bare metal stents (BMS)- and drug-eluting stents (DES)-eras). The primary endpoint was a composite of all-cause mortality, non-fatal myocardial infarction, non-fatal stroke and repeat revascularization within 3 years after the index PCI. Results A total of 1,584 patients were examined. The baseline characteristics became unfavorable over time with regard to age, prevalence of hypertension, presentation with acute coronary syndrome and a reduced left ventricular ejection fraction. The administration of aspirin, statins and β-blockers increased over time. The event-free survival rate for the 3-year cardiovascular events was lower in the DES-era. The adjusted relative risk reduction for 3-year cardiovascular events was 46 % in the DES-era compared with the POBA-era. Conclusion The incidence of 3-year cardiovascular events decreased from 1984 to 2010 in patients with diabetes following PCI, despite the higher risk profiles in the DES-era. PMID:28049984

  9. Clinical Outcomes in Diabetic Patients Who Underwent Percutaneous Coronary Intervention during the Plain Old Balloon Angioplasty (POBA)-, Bare Metal Stents (BMS)- and Drug-eluting Stents (DES)-eras from 1984 to 2010.

    PubMed

    Naito, Ryo; Miyauchi, Katsumi; Konishi, Hirokazu; Tsuboi, Shuta; Ogita, Manabu; Dohi, Tomotaka; Kasai, Takatoshi; Tamura, Hiroshi; Okazaki, Shinya; Isoda, Kikuo; Daida, Hiroyuki

    Objective Diabetes is a negative predictor in coronary artery disease patients. Since the introduction of percutaneous coronary intervention (PCI), PCI has evolved through technological advances in devices, improvements in operators' techniques and the establishment of effective therapeutic protocols. The aim of this study is to examine the changes in the clinical outcomes following PCI in patients with diabetes. Methods We compared the clinical outcomes in patients with diabetes following PCI from 1984 to 2010 at Juntendo University over three eras (plain old balloon angioplasty (POBA)-, bare metal stents (BMS)- and drug-eluting stents (DES)-eras). The primary endpoint was a composite of all-cause mortality, non-fatal myocardial infarction, non-fatal stroke and repeat revascularization within 3 years after the index PCI. Results A total of 1,584 patients were examined. The baseline characteristics became unfavorable over time with regard to age, prevalence of hypertension, presentation with acute coronary syndrome and a reduced left ventricular ejection fraction. The administration of aspirin, statins and -blockers increased over time. The event-free survival rate for the 3-year cardiovascular events was lower in the DES-era. The adjusted relative risk reduction for 3-year cardiovascular events was 46 % in the DES-era compared with the POBA-era. Conclusion The incidence of 3-year cardiovascular events decreased from 1984 to 2010 in patients with diabetes following PCI, despite the higher risk profiles in the DES-era.

  10. Endoscopic stenting for laparoscopic sleeve gastrectomy leaks

    PubMed Central

    Aydın, Mehmet Timuçin; Alahdab, Yeşim Özen; Aras, Orhan; Karip, Bora; Onur, Ender; İşcan, Yalın; Memişoğlu, Kemal

    2016-01-01

    Objective Laparoscopic sleeve gastrectomy is a widely accepted and effective bariatric surgery method. The rate of leakage at the staple-line has been reported to be between 1.5 and 5%. Aside from the use of percutaneous drainage, re-laparoscopy, or abdominal sepsis control by laparotomy, endoscopic esophagogastric stent placement is increasingly preferred as a treatment method. Because laparoscopic sleeve gastrectomy is a widely used modality in our hospital, we aimed to evaluate the rate of leaks and the results of stent placements in our patients. Material and Methods Between January 1st 2010 and August 31st 2014, laparoscopic sleeve gastrectomy was performed on 236 patients by three surgeons. The demographic information and postoperative discharge summaries were collected and analyzed with the permission of the hospital ethics committee. Information about leak treatment management was also collected. Results Leaks after laparoscopic sleeve gastrectomy in four patients were stented in the first postoperative month. Short (12 cm) Hanora® (M.I.Tech, Gyeonggi-do, Korea) self-expandable coated stents were placed in two patients, and long (24 cm) Hanora® self-expandable coated stents were placed in the other two. The stents were removed after one month in two patients, two and a half months later in one, and five months later in another patient. The leaks were demonstrated to be healed in all patients after stent removal. Endoscopic stent revision was performed in one patient due to migration of the stent and in another for stent breakage. Conclusion The success rate of treatment of leaks after laparoscopic sleeve gastrectomy by stent placement has been variable in the literature. The success in early stent placement has been shown to be related to physician expertise. According to the results of our patients, we suggest that endoscopic stent placement in the early stage after controlling sepsis is an effective method in the management of leaks. PMID:28149125

  11. [Absorbable coronary stents. New promising technology].

    PubMed

    Erbel, Raimund; Böse, Dirk; Haude, Michael; Kordish, Igor; Churzidze, Sofia; Malyar, Nasser; Konorza, Thomas; Sack, Stefan

    2007-06-01

    Coronary stent implantation started in Germany 20 years ago. In the beginning, the progress was very slow and accelerated 10 years later. Meanwhile, coronary stent implantation is a standard procedure in interventional cardiology. From the beginning of permanent stent implantation, research started to provide temporary stenting of coronary arteries, first with catheter-based systems, later with stent-alone technology. Stents were produced from polymers or metal. The first polymer stent implantation failed except the Igaki-Tamai stent in Japan. Newly developed absorbable polymer stents seem to be very promising, as intravascular ultrasound (IVUS) and optical coherence tomography have demonstrated. Temporary metal stents were developed based on iron and magnesium. Currently, the iron stent is tested in peripheral arteries. The absorbable magnesium stent (Biotronik, Berlin, Germany) was tested in peripheral arteries below the knee and meanwhile in the multicenter international PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting with Absorbable Metal Stents) study. The first magnesium stent implantation was performed on July 30, 2004 after extended experimental testing in Essen. The magnesium stent behaved like a bare-metal stent with low recoil of 5-7%. The stent struts were absorbed when tested with IVUS. Stent struts were not visible by fluoroscopy or computed tomography (CT) as well as magnetic resonance imaging (MRI). That means, that the magnesium stent is invisible and therefore CT and MRI can be used for imaging of interventions. Only using micro-CT the stent struts were visible. The absorption process could be demonstrated in a patient 18 days after implantation due to suspected acute coronary syndrome, which was excluded. IVUS showed a nice open lumen. Stent struts were no longer visible, but replaced by tissue indicating the previous stent location. Coronary angiography after 4 months showed an ischemia-driven target lesion

  12. Iliocaval Confluence Stenting for Chronic Venous Obstructions

    SciTech Connect

    Graaf, Rick de; Wolf, Mark de; Sailer, Anna M.; Laanen, Jorinde van Wittens, Cees; Jalaie, Houman

    2015-10-15

    PurposeDifferent techniques have been described for stenting of venous obstructions. We report our experience with two different confluence stenting techniques to treat chronic bi-iliocaval obstructions.Materials and MethodsBetween 11/2009 and 08/2014 we treated 40 patients for chronic total bi-iliocaval obstructions. Pre-operative magnetic resonance venography showed bilateral extensive post-thrombotic scarring in common and external iliac veins as well as obstruction of the inferior vena cava (IVC). Stenting of the IVC was performed with large self-expandable stents down to the level of the iliocaval confluence. To bridge the confluence, either self-expandable stents were placed inside the IVC stent (24 patients, SECS group) or high radial force balloon-expandable stents were placed at the same level (16 patients, BECS group). In both cases, bilateral iliac extensions were performed using nitinol stents.ResultsRecanalization was achieved for all patients. In 15 (38 %) patients, a hybrid procedure with endophlebectomy and arteriovenous fistula creation needed to be performed because of significant involvement of inflow vessels below the inguinal ligament. Mean follow-up was 443 ± 438 days (range 7–1683 days). For all patients, primary, assisted-primary, and secondary patency rate at 36 months were 70, 73, and 78 %, respectively. Twelve-month patency rates in the SECS group were 85, 85, and 95 % for primary, assisted-primary, and secondary patency. In the BECS group, primary patency was 100 % during a mean follow-up period of 134 ± 118 (range 29–337) days.ConclusionStenting of chronic bi-iliocaval obstruction shows relatively high patency rates at medium follow-up. Short-term patency seems to favor confluence stenting with balloon-expandable stents.

  13. Nitinol Esophageal Stents: New Designs and Clinical Indications

    SciTech Connect

    Strecker, Ernst-Peter; Boos, Irene; Vetter, Sylvia; Strohm, Michael; Domschke, Sigurd

    1996-11-15

    Purpose: To evaluate the clinical use of covered and noncovered, knitted nitinol stents in patients presenting new stent indications. Methods: Self-expandable, knitted nitinol stents were implanted in four patients for treatment of dysphagia. In two patients who had malignant strictures and had esophago-respiratory fistulae and in one patient with an esophagocutaneous fistula, polytetrafluoroethylene (PTFE)-covered stents were implanted. One patient received a noncovered stent, but a retrograde approach through a percutaneous endoscopic gastrostomy (PEG) fistula had to be chosen for recanalization of an esophageal occlusion. Two patients received stents for treatment of benign strictures. Results: Recanalization of the stricture and stent implantation were performed under fluoroscopic control without any procedure-related morbidity or mortality. Dysphagia improved in all patients and the esophageal fistulae could be sealed off by covered stents. During a maximum follow-up of 18 months, there was no stent migration or esophageal perforation. Complications observed were stent stenosis due to food impaction (1/4) and benign stent stenosis (2/2). Most complications could be treated by the interventional radiologist. Conclusion: Self-expandable, covered Nitinol stents provide an option for the treatment of dysphagia combined with esophageal fistulae. In combination with interventional radiology techniques, even complex strictures are accessible. For benign strictures, the value of stent treatment has not yet been proven.

  14. (Barely) solid Li(NH3)4: the electronics of an expanded metal.

    PubMed

    Zurek, Eva; Wen, Xiao-Dong; Hoffmann, Roald

    2011-03-16

    The highly expanded metal, lithium(0)tetraamine, and its electronic structure is as full of complexity and surprises as the lithium solutions in anhydrous ammonia from which it crystallizes at 90 K. Our theoretical studies of the Phase II, Z = 8, I43d structure of this material reveal that the molecular building block is an almost ideal tetrahedron, in agreement with recent experiments. Close in enthalpy at P = 1 atm, and consistent with the low melting point, are bcc and Cs-IV configurations. Under pressure, the I43d structure emerges as more stable than its alternatives. In this phase six relatively narrow bands, four of them occupied, separate from the conduction and valence bands. We trace these bands to pockets of electron density arising between sterically encumbered ammonias, six such pockets in the Z = 8 unit cell. The observed band structure can be explained by considering a Jortner-type model, where pseudoatoms are placed in these holes. The electride Li(NH(3))(4), while not a very good metal, is a unique material, by virtue of its low melting point.

  15. Silane surface modification for improved bioadhesion of esophageal stents

    PubMed Central

    Karakoy, Mert; Gultepe, Evin; Pandey, Shivendra; Khashab, Mouen A.; Gracias, David H.

    2014-01-01

    Stent migration occurs in 10-40% of patients who undergo placement of esophageal stents, with higher migration rates seen in those treated for benign esophageal disorders. This remains a major drawback of esophageal stent therapy. In this paper, we propose a new surface modification method to increase the adhesion between self-expandable metallic stents (SEMS) and tissue while preserving their removability. Taking advantage of the well-known affinity between epoxide and amine terminated silane coupling agents with amine and carboxyl groups that are abundant in proteins and related molecules in the human body; we modified the surfaces of silicone coated esophageal SEMS with these adhesive self-assembled monolayers (SAMs). We utilized vapor phase silanization to modify the surfaces of different substrates including PDMS strips and SEMS, and measured the force required to slide these substrates on a tissue piece. Our results suggest that surface modification of esophageal SEMS via covalent attachment of protein-binding coupling agents improves adhesion to tissue and could offer a solution to reduce SEMS migration while preserving their removability. PMID:25663731

  16. Silane surface modification for improved bioadhesion of esophageal stents

    NASA Astrophysics Data System (ADS)

    Karakoy, Mert; Gultepe, Evin; Pandey, Shivendra; Khashab, Mouen A.; Gracias, David H.

    2014-08-01

    Stent migration occurs in 10-40% of patients who undergo placement of esophageal stents, with higher migration rates seen in those treated for benign esophageal disorders. This remains a major drawback of esophageal stent therapy. In this paper, we propose a new surface modification method to increase the adhesion between self-expandable metallic stents (SEMS) and tissue while preserving their removability. Taking advantage of the well-known affinity between epoxide and amine terminated silane coupling agents with amine and carboxyl groups that are abundant in proteins and related molecules in the human body; we modified the surfaces of silicone coated esophageal SEMS with these adhesive self-assembled monolayers (SAMs). We utilized vapor phase silanization to modify the surfaces of different substrates including PDMS strips and SEMS, and measured the force required to slide these substrates on a tissue piece. Our results suggest that surface modification of esophageal SEMS via covalent attachment of protein-binding coupling agents improves adhesion to tissue and could offer a solution to reduce SEMS migration while preserving their removability.

  17. Biliary and pancreatic stenting: Devices and insertion techniques in therapeutic endoscopic retrograde cholangiopancreatography and endoscopic ultrasonography

    PubMed Central

    Mangiavillano, Benedetto; Pagano, Nico; Baron, Todd H; Arena, Monica; Iabichino, Giuseppe; Consolo, Pierluigi; Opocher, Enrico; Luigiano, Carmelo

    2016-01-01

    Stents are tubular devices made of plastic or metal. Endoscopic stenting is the most common treatment for obstruction of the common bile duct or of the main pancreatic duct, but also employed for the treatment of bilio-pancreatic leakages, for preventing post- endoscopic retrograde cholangiopancreatography pancreatitis and to drain the gallbladder and pancreatic fluid collections. Recent progresses in techniques of stent insertion and metal stent design are represented by new, fully-covered lumen apposing metal stents. These stents are specifically designed for transmural drainage, with a saddle-shape design and bilateral flanges, to provide lumen-to-lumen anchoring, reducing the risk of migration and leakage. This review is an update of the technique of stent insertion and metal stent deployment, of the most recent data available on stent types and characteristics and the new applications for biliopancreatic stents. PMID:26862364

  18. An Assessment of Radiologically Inserted Transoral and Transgastric Gastroduodenal Stents to Treat Malignant Gastric Outlet Obstruction

    SciTech Connect

    Miller, Bethany H. T.; Griffiths, Ewen A.; Pursnani, Kishore G. Ward, Jeremy B.; Stockwell, Robert C.

    2013-12-15

    IntroductionSelf-expanding metallic stents (SEMS) are used to palliate malignant gastric outlet obstruction (GOO) and are useful in patients with limited life expectancy or severe medical comorbidity, which would preclude surgery. Stenting can be performed transorally or by a percutaneous transgastric technique. Our goal was to review the outcome of patients who underwent radiological SEMS insertion performed by a single consultant interventional radiologist. Methods: Patients were identified from a prospectively collected database held by one consultant radiologist. Data were retrieved from radiological reports, multidisciplinary team meetings, and the patients' case notes. Univariate survival analysis was performed. Results: Between December 2000 and January 2011, 100 patients (63 males, 37 females) had 110 gastroduodenal stenting procedures. Median age was 73 (range 39-89) years. SEMS were inserted transorally (n = 66) or transgastrically (n = 44). Site of obstruction was the stomach (n = 37), duodenum (n = 50), gastric pull-up (n = 10), or gastroenterostomy (n = 13). Seven patients required biliary stents. Technical success was 86.4 %: 83.3 % for transoral insertion, 90.9 % for transgastric insertion. Eleven patients developed complications. Median GOO severity score: 1 pre-stenting, 2 post-stenting (p = 0.0001). Median survival was 54 (range 1-624) days. Post-stenting GOO severity score was predictive of survival (p = 0.0001). Conclusions: The technical success rate for insertion of palliative SEMS is high. Insertional technique can be tailored to the individual depending on the location of the tumor and whether it is possible to access the stomach percutaneously. Patients who have successful stenting and return to eating a soft/normal diet have a statistically significant increase in survival.

  19. The Use of Prosthetic Stents in Tracheobronchial, Gastrointestinal, and Genitourinary Diseases

    PubMed Central

    Hughes, Rollin W.; Oesterling, Joseph E.; Cortese, Denis A.

    1994-01-01

    The concept of using a stent to maintain patency of a lumen is not new. As early as 1969, stents were being investigated in the peripheral arterial system as a means of preventing restenosis after dilatation by balloon angioplasty (Dotter, 1969). Since then, numerous reports have demonstrated the use of stents in both the peripheral and coronary artery systems (Maass et al., 1982; Dotter et al., 1983; Wright et al., 1985; Palmaz et al., 1987). Concomitant with the investigation of expandable endovascular metal prosthesis has been the development of prosthetic devices for management of tracheobronchial, gastrointestinal, and genitourinary diseases. We will review the use of endoscopically placed prosthetic devices in the management of diseases affecting these systems. PMID:18493334

  20. Usefulness of Drug-Eluting Balloons for Bare-Metal and Drug-Eluting In-Stent Restenosis (from the RIBS IV and V Randomized Trials).

    PubMed

    Alfonso, Fernando; Pérez-Vizcayno, María José; García Del Blanco, Bruno; García-Touchard, Arturo; López-Mínguez, José-Ramón; Sabaté, Manel; Zueco, Javier; Melgares, Rafael; Hernández, Rosana; Moreno, Raul; Domínguez, Antonio; Sanchís, Juan; Moris, Cesar; Moreu, José; Cequier, Angel; Romaguera, Rafael; Rivero, Fernando; Cuesta, Javier; Gonzalo, Nieves; Jiménez-Quevedo, Pilar; Cárdenas, Alberto; Fernández, Cristina

    2017-04-01

    Treatment of patients with drug-eluting stent (DES) in-stent restenosis (ISR) is particularly challenging. We sought to compare results of drug-eluting balloons in patients with DES-ISR with those in patients with bare-metal stent (BMS) ISR. A pooled analysis of the Restenosis Intra-Stent: Drug-Eluting Balloon versus Everolimus-Eluting Stent IV and V randomized trials was performed. Both trials had identical inclusion and exclusion criteria. Results of drug-eluting balloons in 95 patients with BMS-ISR and 154 patients with DES-ISR were compared. Patients with DES-ISR were more frequently diabetics, presented more often as an acute coronary syndrome and had more severe lesions and more frequently a focal pattern, including edge-ISR. Late angiographic findings (92% of eligible patients), including minimal lumen diameter (1.80 ± 0.6 vs 2.01 ± 0.6 mm, p = 0.001; absolute mean difference 0.21 mm; 95% confidence interval 0.04 to 0.38; p = 0.014) and restenosis rate (19% vs 9.5%, p <0.05) were poorer in DES-ISR. Results were consistent across 10 prespecified subgroups. Moreover, on multiple linear regression analysis, minimal lumen diameter at follow-up remained significantly smaller in patients with DES-ISR after adjusting for potential confounders (adjusted absolute mean difference 0.17 mm; 95% confidence interval 0.04 to 0.41; p = 0.019). Finally, at 1-year clinical follow-up (100% of patients), rates of target vessel revascularization (16% vs 6%, p = 0.02) and of the main combined clinical end point (18% vs 8%, p = 0.03) were significantly higher in patients treated for DES-ISR. In conclusion, this study confirms the efficacy of DEB for patients with ISR. However, the long-term clinical and angiographic results of DEB are poorer in patients with DES-ISR than in those with BMS-ISR. (ClinicalTrials.govIdentifier:NCT01239953&NCT01239940).

  1. Comparing the Clinical Outcomes between Drug Eluting Stents and Bare Metal Stents in Patients with Insulin-Treated Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of 10 Randomized Controlled Trials

    PubMed Central

    Bundhun, Pravesh Kumar; Bhurtu, Akash; Soogund, Mohammad Zafooruddin Sani; Long, Man-Yun

    2016-01-01

    Background Several studies have shown Drug Eluting Stents (DES) to be better compared to Bare Metal Stents (BMS) in patients with type 2 Diabetes Mellitus (T2DM). Since, the adverse clinical outcomes in patients with Insulin-Treated Type 2 Diabetes Mellitus (ITDM) implanted with DES and BMS have not been previously studied, we aim to compare the clinical outcomes in similar patients with cardiovascular diseases, treated with DES and BMS. Methods Randomized Controlled Trials (RCTs) comparing patients treated with DES and BMS were searched from PubMed and EMBASE databases. Outcome data for the patients with ITDM were carefully extracted. Major Adverse Cardiac Events (MACEs), mortality, Target Vessel Revascularization (TVR), Target Lesion Revascularization (TLR), Myocardial Infarction (MI) and Stent Thrombosis (ST) were considered as the clinical endpoints for this analysis. Odds ratios (OR) with 95% confidence intervals (CIs) were calculated and the pooled analyses were performed with RevMan 5.3 software. Results Ten RCTs consisting of 830 patients with ITDM (477 patients in the DES group and 353 patients in the BMS group) from a total number of 9,141 patients were included in this analysis. During a follow-up period from one month to one year, MACEs were not increased with the use of DES in these patients with ITDM. At 9 months, MACEs were significantly lower in the DES group with OR: 0.40, 95% CI: 0.23–0.72; P = 0.002 with no increase in mortality. TVR and TLR also favored the DES group with OR: 0.44, 95% CI: 0.22–0.88, P = 0.02 and OR: 0.28, 95% CI: 0.14–0.53; P = 0.0001 respectively at 9 months, and OR: 0.46, 95% CI: 0.23–0.94, P = 0.03 and OR: 0.28, 95% CI: 0.14–0.55; P = 0.0003 respectively at one year. Results for MI, and ST were not statistically significant. Conclusion Compared to BMS, DES were associated with a significantly lower rate of repeated revascularization, without any increase in MACEs or mortality in these patients with ITDM during a

  2. Increased endothelial cell adhesion on plasma modified nanostructured polymeric and metallic surfaces for vascular stent applications.

    PubMed

    Pareta, Rajesh A; Reising, Alexander B; Miller, Tiffany; Storey, Dan; Webster, Thomas J

    2009-06-15

    Techniques to regenerate the vasculature have risen considerably over the last few decades due to the increased clinical diagnosis of artery narrowing and blood vessel blockage. Although initially re-establishing blood flow, current small diameter vascular regenerative materials often eventually cause thrombosis and restenosis due to a lack of initial endothelial cell coverage on such materials. The objective of this in vitro study was to evaluate commonly used vascular materials (specifically, polyethylene terephthalate, polytetrafluoroethylene, polyvinyl chloride, polyurethane, nylon, commercially pure titanium, and a titanium alloy (Ti6Al4V)) modified using an ionic plasma deposition (IPD) process and a nitrogen ion implantation plasma deposition (NIIPD) process. Such surface modifications have been previously shown to create nanostructured surface features which mimic the natural nanostructured surface features of blood vessels. The modified and unmodified surfaces were characterized by scanning electron microscopy, atomic force microscopy and surface energy measurements. Furthermore, in vitro endothelial cell adhesion tests (a key first step for vascular material endothelialization) demonstrated increased endothelial cell adhesion on many modified (with IPD and NIIPD + IPD) compared to unmodified samples. In general, endothelial cell adhesion increased with nanoroughness and surface energy but demonstrated a decreased endothelial cell adhesion trend after an optimal coating surface energy value was reached. Thus, results from this study provided materials and a versatile surface modification process that can potentially increase endothelialization faster than current unmodified (conventional) polymer and metallic vascular materials.

  3. Factors That Affect Stent-Related Complications in Patients with Malignant Obstruction of the Esophagus or Gastric Cardia

    PubMed Central

    Iwasaki, Hiroyasu; Mizushima, Takashi; Suzuki, Yuta; Fukusada, Shigeki; Kachi, Kenta; Ozeki, Takanori; Anbe, Kaiki; Tsukamoto, Hironobu; Okumura, Fumihiro; Joh, Takashi; Sano, Hitoshi

    2017-01-01

    Background/Aims Self-expandable metallic stent (SEMS) placement is effective for dysphagia that results from malignant obstruction of the esophagus or gastric cardia; however, stent-related complications may be life-threatening. Thus, the goal of this study was to identify risk factors associated with complications following esophageal stenting. Methods Of the 71 patients who underwent SEMS placement for dysphagia as a result of malignant stricture of the esophagus or gastric cardia, 53 patients with squamous cell carcinoma or adenocarcinoma, without previous SEMS placement, without a fistula, and without recurrent tumor after surgery were retrospectively identified. The occurrence of stent-related complications was used as an endpoint. Results Stent-related complications were identified in 26 patients (49.1%), and major complications occurred in 14 patients (26.4%). The use of an Ultraflex stent (odds ratio [OR], 6.81; 95% confidence interval [CI], 1.54 to 30.00; p=0.011) and prior chemotherapy (OR, 6.13; 95% CI, 1.46 to 25.70; p=0.013) were significantly associated with stent-related complications. Moreover, the use of an Ultraflex stent (OR, 19.60; 95% CI, 2.26 to 170.00; p=0.007) and prior radiation (OR, 25.70; 95% CI, 2.37 to 280.00; p=0.008) significantly increased the risk of major complications. Conclusions The use of an Ultraflex stent and prior radiation and/or chemotherapy may represent risk factors for complications following esophageal SEMS placement. PMID:27728966

  4. Development of a New Hybrid Biodegradable Drug-Eluting Stent for the Treatment of Peripheral Artery Disease.

    PubMed

    Lee, Jung-Hee; Kim, Soon-Joong; Park, Se-Il; Ko, Young-Guk; Choi, Donghoon; Hong, Myeong-Ki; Jang, Yangsoo

    2016-01-01

    This study aimed to develop a new biodegradable stent for peripheral artery disease (PAD) that could provide sufficient radial force to maintain long-term patency and flexibility. All self-expandable hybrid biodegradable stents were designed by using a knitting structure composed of poly-L-lactic acid (PLLA) and nitinol. Four different types of stents were implanted in 20 iliac arteries in 10 mini pigs as follows: a bare-metal stent (BMS) (group 1, n = 5), a drug-free hybrid stent (group 2, n = 5), a 50% (50 : 100, w/w) paclitaxel (PTX)/poly-lactide-co-glycolic acid (PLGA; fast PTX-releasing form) hybrid stent (group 3, n = 5), and a 30% (30 : 100, w/w) PTX/PLGA (slow PTX-releasing form) hybrid stent (group 4, n = 5). We performed follow-up angiography and intravascular ultrasonography (IVUS) at 4 and 8 weeks. In a comparison of groups 1, 2, 3, and 4, less diameter stenosis was observed in the angiographic analysis for group 4 at the 4-week follow-up (19.0%  ±  12.7% versus 39.3%  ±  18.1% versus 46.8%  ±  38.0% versus 4.8%  ±  4.2%, resp.; p = 0.032). IVUS findings further suggested that the neointima of the patients in group 4 tended to be lesser than those of the others. Our new biodegradable 30% PTX/PLGA (slow-releasing form) stent showed more favorable results for patency than the other stent types.

  5. Development of a New Hybrid Biodegradable Drug-Eluting Stent for the Treatment of Peripheral Artery Disease

    PubMed Central

    Kim, Soon-Joong; Park, Se-Il; Jang, Yangsoo

    2016-01-01

    This study aimed to develop a new biodegradable stent for peripheral artery disease (PAD) that could provide sufficient radial force to maintain long-term patency and flexibility. All self-expandable hybrid biodegradable stents were designed by using a knitting structure composed of poly-L-lactic acid (PLLA) and nitinol. Four different types of stents were implanted in 20 iliac arteries in 10 mini pigs as follows: a bare-metal stent (BMS) (group 1, n = 5), a drug-free hybrid stent (group 2, n = 5), a 50% (50 : 100, w/w) paclitaxel (PTX)/poly-lactide-co-glycolic acid (PLGA; fast PTX-releasing form) hybrid stent (group 3, n = 5), and a 30% (30 : 100, w/w) PTX/PLGA (slow PTX-releasing form) hybrid stent (group 4, n = 5). We performed follow-up angiography and intravascular ultrasonography (IVUS) at 4 and 8 weeks. In a comparison of groups 1, 2, 3, and 4, less diameter stenosis was observed in the angiographic analysis for group 4 at the 4-week follow-up (19.0%  ±  12.7% versus 39.3%  ±  18.1% versus 46.8%  ±  38.0% versus 4.8%  ±  4.2%, resp.; p = 0.032). IVUS findings further suggested that the neointima of the patients in group 4 tended to be lesser than those of the others. Our new biodegradable 30% PTX/PLGA (slow-releasing form) stent showed more favorable results for patency than the other stent types. PMID:27999810

  6. Treatment of Post-Stent Gastroesophageal Reflux by Anti-Reflux Z-Stent

    SciTech Connect

    Davies, Roger Philip; Kew, Jacqueline; Byrne, Peter D.

    2000-11-15

    Severe symptoms of heartburn and retrosternal pain consistent with gastro-esophageal reflux (GER) developed in a patient following placement of a conventional self-expanding 16-24-mm-diameter x 12-cm-long esophageal stent across the gastroesophageal junction to treat an obstructing esophageal carcinoma. A second 18-mm-diameter x 10-cm-long esophageal stent with anti-reflux valve was deployed coaxially and reduced symptomatic GER immediately. Improvement was sustained at 4-month follow-up. An anti-reflux stent can be successfully used to treat significant symptomatic GER after conventional stenting.

  7. Prevention of stent thrombosis: challenges and solutions

    PubMed Central

    Reejhsinghani, Risheen; Lotfi, Amir S

    2015-01-01

    Stent thrombosis is an uncommon but serious complication which carries with it significant mortality and morbidity. This review analyzes the entity of stent thrombosis from a historical and clinical perspective, and chronicles the evolution of this condition through the various generations of stent development, from bare metal to first-generation, second-generation, and third-generation drug-eluting stents. It also delineates the specific risk factors associated with stent thrombosis and comprehensively examines the literature related to each of these risks. Finally, it highlights the preventative strategies that can be garnered from the existing data, and concludes that a multifactorial approach is necessary to combat the occurrence of stent thrombosis, with higher risk groups, such as patients with ST segment elevation myocardial infarction, meriting further research. PMID:25657588

  8. Nitinol stent design - understanding axial buckling.

    PubMed

    McGrath, D J; O'Brien, B; Bruzzi, M; McHugh, P E

    2014-12-01

    Nitinol׳s superelastic properties permit self-expanding stents to be crimped without plastic deformation, but its nonlinear properties can contribute towards stent buckling. This study investigates the axial buckling of a prototype tracheobronchial nitinol stent design during crimping, with the objective of eliminating buckling from the design. To capture the stent buckling mechanism a computational model of a radial force test is simulated, where small geometric defects are introduced to remove symmetry and allow buckling to occur. With the buckling mechanism ascertained, a sensitivity study is carried out to examine the effect that the transitional plateau region of the nitinol loading curve has on stent stability. Results of this analysis are then used to redesign the stent and remove buckling. It is found that the transitional plateau region can have a significant effect on the stability of a stent during crimping, and by reducing the amount of transitional material within the stent hinges during loading the stability of a nitinol stent can be increased.

  9. Comparison of Long-Term Safety and Efficacy Outcomes after Drug-Eluting and Bare-Metal Stent Use across Racial Groups: insights from NHLBI Dynamic Registry

    PubMed Central

    Olafiranye, Oladipupo; Vlachos, Helen; Mulukutla, Suresh R.; Marroquin, Oscar; Selzer, Faith; Kelsey, Sheryl F.; Williams, David O.; Strollo, Patrick J.; Reis, Steven E.; Lee, Joon S.; Smith, AJ. Conrad

    2015-01-01

    Background Long-term data on outcomes after percutaneous coronary intervention (PCI) with drug-eluting stent (DES) and bare-metal stent (BMS) across racial groups are limited, and minorities are under-represented in existing clinical trials. Whether DES has better long-term clinical outcomes compared to BMS across racial groups remains to be established. Accordingly, we assessed whether longer-term clinical outcomes are better with DES compared to BMS across racial groups. Methods Using the multicenter National Heart, Lung, and Blood Institute (NHLBI)-sponsored Dynamic Registry, 2-year safety (death, MI) and efficacy (repeat revascularization) outcomes of 3,326 patients who underwent PCI with DES versus BMS were evaluated. Results With propensity-score adjusted analysis, the use of DES, compared to BMS, was associated with a lower risk for death or MI at 2 years for both blacks (adjusted Hazard Ratio (aHR)=0.41, 95% CI 0.25–0.69, p<0.001) and whites (aHR=0.67, 95% CI 0.51–0.90, p=0.007). DES use was associated with a significant 24% lower risk of repeat revascularization in whites (aHR=0.76, 95% CI 0.60–0.97, p=0.03) and with nominal 34% lower risk in blacks (aHR=0.66, 95% CI 0.39–1.13, p=0.13). Conclusion Use of DES in PCI was associated with better long-term safety outcomes across racial groups. Compared to BMS, DES was more effective in reducing repeat revascularization in whites and blacks, but this benefit was attenuated after statistical adjustment in blacks. These findings indicate that DES is superior to BMS in all patients regardless of race. Further studies are needed to determine long-term outcomes across racial groups with newer generation stents. PMID:25697874

  10. Late Stent Thrombosis Associated with Heavy Exercise

    PubMed Central

    Simsek, Ziya; Arslan, Sakir; Gundogdu, Fuat

    2009-01-01

    Bare-metal stents are commonly used in the treatment of coronary artery disease. Stent thrombosis usually occurs within the first 48 hours after stent deployment. After a week, the incidence of thrombosis is low. Late stent thrombosis (after 30 days) is rarely seen; however, its clinical outcomes are severe 30-day mortality rates of 20% to 48% and myocardial infarction rates of 60% to 70%. Herein, we present the case and discuss the treatment of a patient who, after heavy exercise, experienced acute myocardial infarction due to late thrombosis in a bare-metal stent. A 54-year-old man presented with unstable angina pectoris. Coronary angiography revealed critical occlusion of the middle right coronary artery. A bare-metal stent was implanted, and he was discharged from the hospital on a medical regimen. Eleven months later, he presented with acute myocardial infarction, which had developed after heavy exercise. Coronary angiography revealed occlusion of the stent in the right coronary artery. After the occlusion was crossed with a guidewire, balloon angioplasty was applied, and Thrombosis-in-Myocardial-Infarction (TIMI)-3 flow was restored. The patient was asymptomatic during his 5-day hospitalization and was discharged on dual antiplatelet therapy. In addition to presenting this patient's case, we discuss mechanisms that may contribute to late stent thrombosis, implications of the condition, and preventive therapy. PMID:19436813

  11. [A new balloon-expandable plastic endoprosthesis. Initial report of experience with the malleable thermostent].

    PubMed

    Beck, A

    1990-07-01

    A new system of balloon-expandable stents for different purposes is presented. A special plastic material that can be shaped by a hot balloon technique or other internal or external heating modalities has been developed. The plastic material - a distant derivative of polyurethane - is caprolactone, which is soft from 52 degrees C to 70 degrees C. Using balloon techniques, the "thermo-stent" can be modeled to suit the form of the vessels, the bile ducts or the bronchial tree, as required. The balloon can be heated simply by means of a warm NaCl solution, electric matter in the balloon itself or microwaves. The plastic material can even be heated directly, which is especially beneficial if the stent needs to be thicker, e.g. in the bronchial tree, by an electric network within the plastic material, which heats the material to the necessary temperature by electric current. When the balloon is cooled after the dilatation the new form, the plastic has been modeled to is maintained exactly. The advantages of this thermo-stent will be the perfect adaptation to every individual situation in the intraluminal vessels, the bile ducts, and even the bronchi. The problems encountered hitherto with conventional metallic stents, e.g. high thrombogenicity, risk of metal intoxication or metallic rupture of filaments, have not be seen so far in animal experiments.

  12. Residual stresses in coronary artery stents.

    PubMed

    Möller, D; Reimers, W; Pyzalla, A; Fischer, A

    2001-01-01

    In western industrial countries, coronary heart disease is the most common cause of death. The reason is a coronary sclerosis, which by the generation of plaques narrows the inner lumen of an artery and, thus, deteriorates the blood supply. This leads to symptoms like burning pain or increased pressure in the chest, and finally to an under supply and damage of the heart muscle. In order to keep those portions of arteries that are covered by a plaque open, the stent technique was developed in the 1980s and is increasingly used since about 13 years. These stents are usually made of wires or of a slotted tube and are of two kinds: self-expanding and balloon expanding. Both types are implanted after being mounted on a catheter and expanded in the desired position. Self-expanding stents make use of the elastic deformation, while the other group of stents are expanded by a balloon, which brings about a plastic deformation of certain regions of the stent structure. Thus, after implantation, parts of these stents undergo two steps of distinct plastic deformation. First during compression, which is necessary for the mounting procedure on the catheter (crimping), and second during expansion for implantation. In this article, the residual stresses generated during crimping and expansion are presented and discussed. These stresses are stored in the structure of a portion of a stent after implantation and are superimposed on those stresses generated by the more than 700 million cyclic heart beats during the patient's life. This work is a part of several interdisciplinary research projects by the authors in order to gain reliable fail-safe criteria for the static and cyclic mechanical properties of coronary stents.

  13. A novel biliary stent coated with silver nanoparticles prolongs the unobstructed period and survival via anti-bacterial activity

    PubMed Central

    Yang, Fuchun; Ren, Zhigang; Chai, Qinming; Cui, Guangying; Jiang, Li; Chen, Hanjian; Feng, Zhiying; Chen, Xinhua; Ji, Jian; Zhou, Lin; Wang, Weilin; Zheng, Shusen

    2016-01-01

    Symptomatic biliary stricture causes life-threatening complications, such as jaundice, recurrent cholangitis and secondary biliary cirrhosis. Fully covered self-expanding metal stents (FCSEMSs) are gaining acceptance for treatments of benign biliary stricture and palliative management of malignant biliary obstructions. However, the high rate of FCSEMS obstruction limits their clinic use. In this study, we developed a novel biliary stent coated with silver nanoparticles (AgNPs) and investigated its efficacy both in vitro and in vivo. We first identified properties of the AgNP complex using ultraviolet detection. The AgNP complex was stable without AgNP agglomeration, and Ag abundance was correspondingly increased with an increased bilayer number. The AgNP biliary stent demonstrated good performance in the spin-assembly method based on topographic observation. The AgNP biliary stent also exhibited a long-term anti-coagulation effect and a slow process of Ag+ release. In vitro anti-bacteria experiments indicated that the AgNP biliary stent exhibited high-efficiency anti-bacterial activity for both short- and long-term periods. Importantly, application of the AgNP biliary stent significantly prolonged the unobstructed period of the biliary system and improved survival in preclinical studies as a result of its anti-microbial activity and decreased granular tissue formation on the surface of the anastomotic biliary, providing a novel and effective treatment strategy for symptomatic biliary strictures. PMID:26883081

  14. Stent type used does not impact complication rate or placement time but can decrease treatment cost for benign and malignant esophageal lesions

    PubMed Central

    McGaw, Camille; Alkaddour, Ahmad; Vega, Kenneth J; Munoz, Juan Carlos

    2016-01-01

    AIM: To evaluate if differences exist between self-expanding esophageal metal stents (SEMS) and self-expanding esophageal plastic stents (SEPS) when used for benign or malignant esophageal disorders with regard to safety, efficacy, clinical outcomes, placement ease and cost. METHODS: A retrospective analysis was performed to evaluate outcome in patients having SEPS/SEMS placed for malignant or benign esophageal conditions from January 2005 to April 2012. Inclusion criteria was completed SEMS/SEPS placement. Outcomes assessed included technical success of and time required for stent placement, procedure-related complications, need for repeat intervention, hospital stay, mortality and costs. RESULTS: Forty-three patients underwent stent placement for either benign/malignant esophageal disease during the study period. Thirty patients had SEMS (25 male, mean age 59.6 years old) and 13 patients had SEPS (10 male, mean age 61.7 years old). Placement outcome as well as complication rate (SEPS 23.1%, SEMS 25.2%) and in-hospital mortality (SEPS 7.7%, SEMS 6.7%) after placement did not differ between stent types. Migration was the most frequent complication reported occurring equally between types (SEPS 66.7%, SEMS 57.1%). SEPS was less costly than SEMS, decreasing institutional cost by $255/stent. CONCLUSION: SEPS and SEMS have similar outcomes when used for benign or malignant esophageal conditions. However, SEPS use results in decreased costs without impacting care. PMID:27076872

  15. Controlled gene-eluting metal stent fabricated by bio-inspired surface modification with hyaluronic acid and deposition of DNA/PEI polyplexes.

    PubMed

    Kim, Taek Gyoung; Lee, Yuhan; Park, Tae Gwan

    2010-01-15

    A metal stent that could elute plasmid DNA (pDNA) in a controlled manner for substrate-mediated gene transfection was fabricated by first coating with hyaluronic acid (HA) and subsequent deposition of pDNA. To create robust HA coating layer on stainless steel (SS316L) surface, HA was derivatized with dopamine which is a well-known adsorptive molecule involving mussel adhesion process. The HA-coated surface was verified by various analytical techniques and proved to be very hydrophilic and stable, also showing superior biocompatibility in terms of suppressed plasma protein adsorption. For surface loading of pDNA, cationic pDNA/polyethylenimine (PEI) polyplexes were prepared and ionically adsorbed onto the HA-coated SS316L surface. The adsorbed surface exhibited evenly distributed nano-granular topography while the polyplexes maintained the nano-particular morphology. The pDNA was released out in a controlled manner for a period of 10 days with maintaining structural integrity. The dual coated substrate with HA and pDNA/PEI polyplexes exhibited greatly enhanced gene transfection efficiency, when compared to both bare substrate adsorbed with the polyplexes and PEI/pDNA polyelectrolyte multilayers. Dually functionalized stent with HA and pDNA exhibited effective biocompatibility and gene transfection.

  16. Impact of Internal Metallic Ports in Temporary Tissue Expanders on Postmastectomy Radiation Dose Distribution

    SciTech Connect

    Chen, Susie A.; Ogunleye, Tomiwa; Dhabbaan, Anees; Huang, Eugene H.; Losken, Albert; Gabram, Sheryl; Davis, Lawrence; Torres, Mylin A.

    2013-03-01

    Purpose: Temporary tissue expanders (TTE) with an internal magnetic metal port (IMP) have been increasingly used for breast reconstruction in post-mastectomy patients who receive radiation therapy (XRT). We evaluated XRT plans of patients with IMP to determine its effect on XRT dose distribution. Methods and Materials: Original treatment plans with CT simulation scans of 24 consecutive patients who received XRT (ORI), planned without heterogeneity corrections, to a reconstructed breast containing an IMP were used. Two additional treatment plans were then generated: one treatment plan with the IMP assigned the electron density of the rare earth magnet, nickel plated neodymium-iron-boron (HET), and a second treatment plan with the IMP assigned a CT value of 1 to simulate a homogeneous breast without an IMP (BRS). All plans were prescribed 50 Gy to the reconstructed breast (CTV). Results: CTV coverage by 50 Gy was significantly lower in the HET (mean 87.7% CTV) than in either the ORI (mean 99.7% CTV, P<.001) or BRS plans (mean 95.0% CTV, P<.001). The effect of the port was more pronounced on CT slices containing the IMP with prescription dose coverage of the CTV being less in the HET than in either ORI (mean difference 33.6%, P<.01) or BRS plans (mean difference 30.1%, P<.001). HET had a less homogeneous and conformal dose distribution than BRS or ORI. Conclusion: IMPs increase dose heterogeneity and reduce dose to the breast CTV through attenuation of the beam. For optimal XRT treatment, heterogeneity corrections should be used in XRT planning for patients with TTE with IMP, as the IMP impacts dose distribution.

  17. Stenting for Peripheral Artery Disease of the Lower Extremities

    PubMed Central

    2010-01-01

    . Summary of Findings Balloon-expandable stents vs PTA in superficial femoral artery disease Based on a moderate quality of evidence, there is no significant difference in patency between primary stenting using balloon-expandable bare metal stents and PTA at 6, 12 and 24 months in patients with superficial femoral artery disease. The pooled OR for patency and their corresponding 95% CI are: 6 months 1.26 (0.74, 2.13); 12 months 0.95 (0.66, 1.38); and 24 months 0.72 (0.34. 1.55). There is no significant difference in clinical improvement, re-interventions, peri and post operative complications, mortality and amputations between primary stenting using balloon-expandable bare stents and PTA in patients with superficial femoral artery. The pooled OR and their corresponding 95% CI are clinical improvement 0.85 (0.50, 1.42); ankle brachial index 0.01 (-0.02, 0.04) re-intervention 0.83 (0.26, 2.65); complications 0.73 (0.43, 1.22); all cause mortality 1.08 (0.59, 1.97) and amputation rates 0.41 (0.14, 1.18). Self-expandable stents vs PTA in superficial femoral artery disease Based on a moderate quality of evidence, primary stenting using self-expandable bare metal stents is associated with significant improvement in patency at 6, 12 and 24 months in patients with superficial femoral artery disease. The pooled OR for patency and their corresponding 95% CI are: 6 months 2.35 (1.06, 5.23); 12 months 1.54 (1.01, 2.35); and 24 months 2.18 (1.00. 4.78). However, the benefit of primary stenting is not observed for clinical improvement, re-interventions, peri and post operative complications, mortality and amputation in patients with superficial femoral artery disease. The pooled OR and their corresponding 95% CI are clinical improvement 0.61 (0.37, 1.01); ankle brachial index 0.01 (-0.06, 0.08) re-intervention 0.60 (0.36, 1.02); complications 1.60 (0.53, 4.85); all cause mortality 3.84 (0.74, 19.22) and amputation rates 1.96 (0.20, 18.86). Balloon expandable stents vs PTA in iliac artery

  18. Stent thrombosis in 2008: definition, predictors, prognosis and treatment.

    PubMed

    Lemesle, Gilles; Delhaye, Cédric; Bonello, Laurent; de Labriolle, Axel; Waksman, Ron; Pichard, Augusto

    2008-01-01

    Stent thrombosis remains a major pitfall of stent implantation in contemporary percutaneous coronary intervention, leading to high rates of death and nonfatal myocardial infarction (MI). Recently, the emergence of drug-eluting stents (DES) has raised concerns regarding the occurrence of late and very late stent thrombosis. Last year, a standardized definition of stent thrombosis was established to provide consistency in the reporting of this complication and to enable accurate and reliable data to be described for both types of stents: bare metal and drug eluting. Subsequent to the publication of this new definition, many updated data have been reported in the literature. On the other hand, antiplatelet therapy response variability is a recent concept and its real place in the pathogenesis of stent thrombosis is yet to be determined. In this article, we review the definition of and predictors for stent thrombosis focusing on DES use and variability in response to antiplatelet therapy, prognosis and treatment.

  19. Angioplasty and Vascular Stenting

    MedlinePlus

    ... Drug-coated (also called drug-eluting) stents have recently been approved for clinical use by the U.S. ... you notify the MRI department that you have recently had a stent. Although stents used today may ...

  20. Auxetic oesophageal stents: structure and mechanical properties.

    PubMed

    Ali, Murtaza Najabat; Busfield, James J C; Rehman, Ihtesham U

    2014-02-01

    values where the Auxetic stent fails. Finite element models of both Auxetic film and Auxetic stent were developed, and the results were compared with experimental results with a good agreement. The tensile testing of the Auxetic polyurethane films revealed that the Poisson's ratio of the sample ranged between -0.87 and -0.963 at different uniaxial tensile load values. From the stent expansion test, it was found that the Auxetic oesophageal stent radially expanded from 0.5 to 5.73 mm and longitudinally extended from 0.15 to 1.83 mm at a range of applied pressure increments (0.5-2.7 bar) from the balloon catheter.

  1. Targeting In-Stent-Stenosis with RGD- and CXCL1-Coated Mini-Stents in Mice

    PubMed Central

    Weinandy, Stefan; Schreiber, Fabian; Megens, Remco T. A.; Theelen, Wendy; Smeets, Ralf; Jockenhövel, Stefan; Gries, Thomas; Möller, Martin; Klee, Doris; Weber, Christian; Zernecke, Alma

    2016-01-01

    Atherosclerotic lesions that critically narrow the artery can necessitate an angioplasty and stent implantation. Long-term therapeutic effects, however, are limited by excessive arterial remodeling. We here employed a miniaturized nitinol-stent coated with star-shaped polyethylenglycole (star-PEG), and evaluated its bio-functionalization with RGD and CXCL1 for improving in-stent stenosis after implantation into carotid arteries of mice. Nitinol foils or stents (bare metal) were coated with star-PEG, and bio-functionalized with RGD, or RGD/CXCL1. Cell adhesion to star-PEG-coated nitinol foils was unaltered or reduced, whereas bio-functionalization with RGD but foremost RGD/CXCL1 increased adhesion of early angiogenic outgrowth cells (EOCs) and endothelial cells but not smooth muscle cells when compared with bare metal foils. Stimulation of cells with RGD/CXCL1 furthermore increased the proliferation of EOCs. In vivo, bio-functionalization with RGD/CXCL1 significantly reduced neointima formation and thrombus formation, and increased re-endothelialization in apoE-/- carotid arteries compared with bare-metal nitinol stents, star-PEG-coated stents, and stents bio-functionalized with RGD only. Bio-functionalization of star-PEG-coated nitinol-stents with RGD/CXCL1 reduced in-stent neointima formation. By supporting the adhesion and proliferation of endothelial progenitor cells, RGD/CXCL1 coating of stents may help to accelerate endothelial repair after stent implantation, and thus may harbor the potential to limit the complication of in-stent restenosis in clinical approaches. PMID:27192172

  2. Are bio-absorbable stents the future of SFA treatment?

    PubMed

    Peeters, P; Keirse, K; Verbist, J; Deloose, K; Bosiers, M

    2010-02-01

    Several limitations inherent to the implantation of a metallic device, such as the occurrence of in-stent re-stenosis, in an arterial lumen intuitively explain the interest for developing bio-absorbable stents. Two main types of bio-absorbable stents currently exist: polymer stents and metallic stents. To date, no studies with bio-absorbable stents have been conducted in the superficial femoral artery (SFA). Because of their strut thickness and lack of radial force, polymer stents are no good candidates for endovascular use. Absorbable metal stents (AMS) do have the potential to perform well for artery treatment, although current evidence from in-human coronary and infrapopliteal studies yield unsatisfactory results. Drastic technological improvements are mandatory before AMS can be considered for every day practice. Yet, it is our belief that further development of other metal and non-metal bio-absorbable stents, with or without drug-coating, may lead to the creation of the ultimate SFA stent.

  3. Symptomatic stent cast.

    PubMed

    Keohane, John; Moore, Michael; O'Mahony, Seamus; Crosbie, Orla

    2008-02-01

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  4. Gastroesophageal stenting for the management of post sleeve gastrectomy leak

    PubMed Central

    Guzaiz, Noha; Arabi, Mohammad; Khankan, Azzam; Salman, Refaat; Al-Toki, Mohammed; Qazi, Shahbaz; Alzakari, Abdulmohsin; Al-Moaiqel, Mohammad

    2016-01-01

    Objectives To retrospectively evaluate the effectiveness of gastroesophageal stenting for post sleeve gastrectomy staple line leaks using removable self-expandable stents. Methods Between April 2012 and June 2015, 12 consecutive patients (6 males) with mean age of 34 years: (21-38 years) presented with staple line leak 1-8 weeks after the operation (mean 2.8 weeks). Patients underwent gastroesophageal stenting by interventional radiology. A total of 23 stents were deployed with mean length of 17.8 cm (7-24 cm) and mean diameter 25.6 mm (18-36 mm). Stent re-insertion was needed in 7 patients (9 procedure), while 6 patients required percutaneous collection drainage and 3 patients required endoscopic glue injection with clipping. Two stent removal procedures were carried out under endoscopic visualization after failed stent capture under fluoroscopy, while the remaining stents were successfully removed by interventional radiology. Results Stent placement was technically successful in all patients. Stent migration occurred in 6 patients (50%). There is a tendency for stent migration with shorter stent length (R= -0.557, p=0.008). The mean duration of stenting was 60.5 days (14-137 days). All patients underwent stent removal and resumed oral intake with no recurrence of leak at a mean follow up time of 190 days (14-410 days). Complications included gastrointestinal bleeding (n=1), proximal esophageal stricture (n=1) and stent occlusion (n=1). Conclusion Gastroesophageal stenting as a primary measure after diagnosis of early post sleeve gastrectomy leak appears to offer a safe and effective alternative option in obviating repeat surgical interventions. Minimally invasive interventions may still be required for the management of persistent leak. PMID:27874149

  5. [Value of the optical coherence tomography in the treatment guided of the stent failure. Case report].

    PubMed

    Macías, Enrico; Tellez, Alejandro; Ochoa, Jorge; Ortíz, José E

    2014-01-01

    Since the advent of bare metal and drug-eluting stents, the surgical revascularization have declined considerably, however the thrombosis and in-stent restenosis are important complications of these devices. There are several factors that predispose to thrombosis and in-stent restenosis. Conventional angiography has serious limitations to determine the causes of stent failure. Optical coherence tomography is a very sensitive technique to determine the cause of thrombosis and in-stent restenosis.

  6. Clinical device-related article surface characterization of explanted endovascular stents: evidence of in vivo corrosion.

    PubMed

    Halwani, Dina O; Anderson, Peter G; Brott, Brigitta C; Anayiotos, Andreas S; Lemons, Jack E

    2010-10-01

    Limited information exists regarding the in vivo stability of endovascular stents. Nine excised human vascular segments with implanted stents (n = 16) manufactured from stainless steel, nickel-titanium, tantalum, and cobalt-based alloys were analyzed. The stent/tissue components were separated using an established tissue dissolution protocol and control and explanted stents were evaluated by digital optical and electron microscopy. Metallic content in surrounding tissues was measured by mass spectroscopy. Surface alterations, consistent with corrosion mediated by electrochemical and mechanical factors, were observed in 9 of the 16 explanted stents and were absent from control stents. Tissue dissolved from around corroded stents corresponded with a higher metallic content. The effect of these changes in the microtopography of stents on their mechanical properties (fatigue strength and fracture limit) in addition to the potential for released metallic debris contributing to the biological mechanisms of in-stent restenosis supports the need for further investigations.

  7. Does intravascular ultrasound provide clinical benefits for percutaneous coronary intervention with bare-metal stent implantation? A meta-analysis of randomized controlled trials

    PubMed Central

    2012-01-01

    Background The role of intravascular ultrasound (IVUS) in percutaneous coronary interventions (PCI) is still controversial despite several previously published meta-analyses. A meta-analysis to evaluate the controversial role of IVUS-guided PCI with bare-metal stenting was performed and a previous published meta-analysis was re-evaluated in order to clarify the discrepancy between results of these studies. Methods A systematic review was performed by an electronic search of the PubMed, Embase and Web of Knowledge databases and by a manual search of reference lists for randomized controlled trials published until April 2011, with clinical outcomes and, at least, six months of clinical follow-up. A meta-analysis based on the intention to treat was performed with the selected studies. Results Five studies and 1,754 patients were included. There were no differences in death (OR = 1.86; 95% CI = 0.88-3.95; p = 0.10), non-fatal myocardial infarction (OR = 0.65; 95% CI = 0.27-1.58; p = 0.35) and major adverse cardiac events (OR = 0.74; 95% CI = 0.49-1.13; p = 0.16). An analysis of the previous published meta-analysis strongly suggested the presence of publication bias. Conclusions There is no evidence to recommend routine IVUS-guided PCI with bare-metal stent implantation. This may be explained by the paucity and heterogeneity of the studies published so far. PMID:22999055

  8. Design and Development of Expanded Graphite-Based Non-metallic and Flexible Metamaterial Absorber for X-band Applications

    NASA Astrophysics Data System (ADS)

    Borah, Dipangkar; Bhattacharyya, Nidhi S.

    2017-01-01

    The possibility of using expanded graphite instead of a metallic layer as unit cells and ground planes for metamaterial absorbers in X-band is investigated. A metamaterial absorber was fabricated on a flexible linear low-density polyethylene substrate using an expanded graphite-based circular ring as the unit cell structure. The unit cell was simulated and optimized for which the metamaterial absorber exhibited 98.9% absorption at 11.22 GHz. The fabricated expanded graphite-based absorber showed a reflection loss of -24.51 dB at 11.56 GHz with -10 dB bandwidth of 0.39 GHz (3.37%). The performance of the same structure with copper was also measured. The expanded graphite-based metamaterial absorber showed enhanced performance as compared to the copper-based metamaterial absorber. The width of the ring was varied to tune the reflection loss. The proposed expanded graphite-based metamaterial absorber possesses the advantages of being ultra-thin, flexible and non-corrosive.

  9. Stent overlapping and geometric curvature influence the structural integrity and surface characteristics of coronary nitinol stents.

    PubMed

    Kapnisis, Konstantinos K; Halwani, Dina O; Brott, Brigitta C; Anderson, Peter G; Lemons, Jack E; Anayiotos, Andreas S

    2013-04-01

    Preliminary studies have revealed that some stents undergo corrosion and fatigue-induced fracture in vivo, with significant release of metallic ions into surrounding tissues. A direct link between corrosion and in-stent restenosis has not been clearly established; nonetheless in vitro studies have shown that relatively high concentrations of heavy metal ions can stimulate both inflammatory and fibrotic reactions, which are the main steps in the process of restenosis. To isolate the mechanical effects from the local biochemical effects, accelerated biomechanical testing was performed on single and overlapping Nickel-Titanium (NiTi) stents subjected to various degrees of curvature. Post testing, stents were evaluated using Scanning Electron Microscopy (SEM) to identify the type of surface alterations. Fretting wear was observed in overlapping cases, in both straight and curved configurations. Stent strut fractures occurred in the presence of geometric curvature. Fretting wear and fatigue fractures observed on stents following mechanical simulation were similar to those from previously reported human stent explants. It has been shown that biomechanical factors such as arterial curvature combined with stent overlapping enhance the incidence and degree of wear and fatigue fracture when compared to single stents in a straight tube configuration.

  10. Rare earth metals used in biodegradable magnesium-based stents do not interfere with proliferation of smooth muscle cells but do induce the upregulation of inflammatory genes.

    PubMed

    Drynda, Andreas; Deinet, Nicole; Braun, Nicole; Peuster, Matthias

    2009-11-01

    Rare earth metals are added to corrodible magnesium-based alloys in low amounts (up to 10%) to improve their mechanical properties and to decrease the degradation rate. Cerium (Ce), neodymium (Nd), yttrium (Y), and ytterbium (Yb) are already used for degradable cardiovascular stents. Little is known about the biocompatibility of rare earth metals released during the degradation process of the implant. Therefore the biocompatibility of rare earth metals was assessed with regard to metabolic activity of human vascular smooth muscle cells (SMCs). After coincubation with the trivalent chlorides (0.5-100 microg/mL) of rare earth metals for 24, 72, 144, and 240 h metabolic activity was determined at each time point using the colometric WST-1 test. The tested rare earth metals did not lead to significant changes in metabolic activity over a wide concentration range. However, at high concentrations a decrease was observed. Apoptotic or necrotic effects were not observed. Furthermore, we analyzed the effects of Ce, Nd, Y, and Yb on the expression of genes involved in inflammatory processes. The expression of IL-6, IL-8, and ICAM-1 in SMCs after exposure to Ce, Nd, Y, and Yb (5 and 50 microg/mL) was measured using quantitative real-time PCR. Significant up-regulation of IL-6, IL-8, and ICAM-1 genes were only found after 24 h, mainly for a concentration of 50 microg/mL. Our cell culture data indicate that rare earth metals influence cellular processes of vascular cells. Whether adverse effects occur also in in vivo is the topic of further investigations.

  11. [The bioresorbable coronary stent: a revolution].

    PubMed

    Koegler, Flora; De Benedetti, Edoardo

    2013-04-10

    Coronary angioplasty has undergone several technological revolutions: starting with balloon angioplasty, then with bare metal stent and finally with drug eluting stent (DES), this technique is now mature. However, once we thought the problem of instent restenosis solved with DES, new concerns arise with late and very late stent thrombosis. Should we therefore proscribe DES? How long should be the duration of dual antiplatelet therapy? And how should we manage the patients who need a surgery and are at high risk of bleeding? Are bioresorbable stents the final solution with their initial mechanical properties, then with their drug eluting effect against intra-stent restenosis, and finally with their complete resorption which leaves the artery free of any foreign material?

  12. Recent developments in drug-eluting coronary stents.

    PubMed

    Yildiz, Mustafa; Yildiz, Banu Sahin; Gursoy, Mustafa Ozan; Akin, Ibrahim

    2014-01-01

    The interventional treatment of coronary artery disease was introduced in 1970`s by Andreas Grüntzig. The initial treatment strategy with plain old balloon angioplasty (POBA) was associated with high restenosis rates. The introduction of coronary stents, especially drug-eluting stents (DES) in 2002 has improved the results by lowering the rate of in-stent restenosis from 20-40% in the era of bare-metal stent (BMS) to 6-8%. However, in 2006 with the observation of late stent thrombosis the reputations of DES have decreased. However, improvements in stent design especially antiproliferative agents, polymeric agents as well as stent platforms improved newer generation DES. In controlled trials as well as registries the use of second-generation DES as compared to bare-metal stents (BMS) was associated with better clinical and angiographic results. A further development of these stents with use of biodegradable polymers, polymer-free stents, and biodegradable stents on the basis of poly L-lactide (PLLA) or magnesium resulted in third-generation DES and has been evaluated in preclinical and first clinical trials. However, to date, there is a lack of data comparing these third-generation DES with first- and second-generatrion DES in a large scale.

  13. Fast Virtual Stenting with Active Contour Models in Intracranical Aneurysm

    PubMed Central

    Zhong, Jingru; Long, Yunling; Yan, Huagang; Meng, Qianqian; Zhao, Jing; Zhang, Ying; Yang, Xinjian; Li, Haiyun

    2016-01-01

    Intracranial stents are becoming increasingly a useful option in the treatment of intracranial aneurysms (IAs). Image simulation of the releasing stent configuration together with computational fluid dynamics (CFD) simulation prior to intervention will help surgeons optimize intervention scheme. This paper proposed a fast virtual stenting of IAs based on active contour model (ACM) which was able to virtually release stents within any patient-specific shaped vessel and aneurysm models built on real medical image data. In this method, an initial stent mesh was generated along the centerline of the parent artery without the need for registration between the stent contour and the vessel. Additionally, the diameter of the initial stent volumetric mesh was set to the maximum inscribed sphere diameter of the parent artery to improve the stenting accuracy and save computational cost. At last, a novel criterion for terminating virtual stent expanding that was based on the collision detection of the axis aligned bounding boxes was applied, making the stent expansion free of edge effect. The experiment results of the virtual stenting and the corresponding CFD simulations exhibited the efficacy and accuracy of the ACM based method, which are valuable to intervention scheme selection and therapy plan confirmation. PMID:26876026

  14. Elastic recoil of coronary stents: a comparative analysis.

    PubMed

    Barragan, P; Rieu, R; Garitey, V; Roquebert, P O; Sainsous, J; Silvestri, M; Bayet, G

    2000-05-01

    Minimum elastic recoil (ER) has became an essential feature of new coronary stents when deployed in artheromatous lesions of various morphologies. The ER of coronary stent might be an important component of 6-month restenosis rate by minimizing the luminal loss. We evaluated the intrinsic ER of 23 coronary stents with a mechanical test bench. The amount of ER for one size of stent (3.0 mm) was quantified using a 3D optical contactless machine (Smartscope MVP, Rochester, NY). The stents were expanded on their own balloon for the precrimped stents; the uncrimped stents were expended using identical 3.0-mm balloons. Two types of measurements were done without exterior stress and with a 0.2-bar exterior stress, directly on the stent at the end of balloon expansion, immediately after balloon deflation, and then 30 min, 60 min, and 120 min after. ER ranged from 1.54%+/-0.81% (Bestent BES 15) to 16.51%+/-2.89% (Paragon stent) without stress (P<0.01) and from 2.35%+/-1.14% (Bestent BES 15) to 18.34%+/-2.41% (Cook GR2) under 0.2-bar pressure (P<0.0001). Furthermore, there was a significant reduction between the mean result of tubular stents (TS) and coil stents (CS). The results of in vitro mechanical tests may confirm strongly the interest of a minimum ER in the prevention of the 6-month restenosis.

  15. Coronary aneurysm and stent fracture following stenting of a myocardial bridge.

    PubMed

    Lu, Hao; Ge, Lei; Ge, Junbo

    2016-01-01

    Myocardial bridge is the most common congenital coronary anomaly. We represent an extremely rare case of stent fracture combination with coronary aneurysm following stenting of a myocardial bridge. This 60-years-old male patient underwent coronary angiography in the local hospital four years ago. Coronary angiography revealed a myocardial bridge in the distal left anterior descending coronary artery (LAD). A 3.0 mm × 29 mm sirolimus eluting stent was deployed in the distal LAD. Three years later, repeat coronary angiography showed a large coronary aneurysm in the mid segment of the stent. The patient subsequently underwent coronary artery bypass grafting with left internal mammary artery (LIMA) to the distal segment of the LAD. But six months later, another coronary angiography showed a stent fracture in mid portion of the stent associated with a large coronary aneurysm, and the LIMA graft was totally occluded. A possible mechanism of stent fracture was long-standing and cyclic mechanical stress on the stent by myocardium. These forces over a period of time may lead to metal fatigue and eventually fracture. Based on the observation of fracture and aneurysm in this study, we recommend that myocardial bridge should not be treated with intracoronary stenting. © 2015 Wiley Periodicals, Inc.

  16. Mode of deployment of coronary Palmaz-Schatz stents after implantation with the stent delivery system: an intravascular ultrasound study.

    PubMed

    Kiemeneij, F; Laarman, G; Slagboom, T

    1995-04-01

    The stent delivery system (SDS) is a sheath-covered Palmaz-Schatz stent mounted on a 3.0, 3.5, or 4.0 mm compliant polyethylene balloon catheter; the balloon resists maximal inflation pressures of 5.7, 6.2, or 6.0 atm, respectively. It is postulated that these pressures are too low to obtain optimal stent deployment. Because optimal stent deployment is a prerequisite for optimal short- and long-term outcome, we performed an intravascular ultrasound study to the mode of stent deployment after delivery with the SDS and after high-pressure dilatations with low-compliant, oversized balloon catheters. In 23 patients an intravascular ultrasound study (30 MHz, 4.3F transducer) was performed to the geometry of 29 stents immediately after delivery with the SDS and after successive high-pressure inflations with low-compliant balloons. After delivery with the SDS (3.3 +/- 0.4 mm), stent diameter was 3.0 +/- 0.4 mm. After high-pressure dilatations (12.4 +/- 1.4 atm) with low-compliant balloons (3.9 +/- 0.5 mm), stent diameter increased to 3.4 +/- 0.4 mm (p < 0.001). Only 8 (28%) stents were completely and symmetrically expanded to the corresponding reference diameter with good apposition after delivery with the SDS. Diameter of incomplete deployed stents (n = 16) was 2.8 +/- 0.3 mm. After high-pressure dilatations with low-compliant balloons (3.9 +/- 0.5 mm), diameter increased to 3.4 +/- 0.4 mm (p < 0.001). Now 20 (69%) stents (p = 0.004) became completely and symmetrically expanded to a diameter corresponding to the reference diameter. In conclusion, most stents are suboptimally deployed after delivery with the stent delivery system.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Void structure and intermediate-range fluctuations in the metal-nonmetal transition range in expanded liquid Hg

    NASA Astrophysics Data System (ADS)

    Maruyama, Kenji; Endo, Hirohisa; Hoshino, Hideoki; Hensel, Friedrich

    2009-07-01

    The reverse Monte Carlo and Voronoi-Delaunay analyses have been applied to characterize the intermediate-range fluctuations near the metal-nonmetal transition in expanded liquid Hg. An analysis of voids acts as a useful adjunct to the normally discussed structural properties in interpreting the origin of intermediate-range fluctuations in the expanded liquids. The results for Hg-based and void-based partial pair distribution functions and the partial coordination number distributions reveal that the metallic domains (M domains) are built with packing of tetrahedral Hg4 blocks. The M domains transform into the nonmetallic domains (NM domains) creating large voids (L voids) ˜3.1Å in radius, which are supported by the network linked with tetrahedral Hg4 blocks containing small voids (S voids) ˜2.3Å in radius at densities of 9.2-10.5gcm-3 , where the coordination number is rapidly reduced below six. The estimated density variations in Scc'(0) from “domain model” and “void model” exhibit a peak around 10.5gcm-3 , which indicates that M domains and NM domains coexist near the metal-nonmetal transition region. There appears the prepeak at 0.8-1.2Å-1 in the partial structure factor of L voids around the L voids, SLV-LV'(Q) , suggesting the chemical ordering of L voids. It follows that the intermediate-range concentration fluctuations resulting in microphase separation (clustering) of NM domains and M domains are reflected in the structural change near the metal-nonmetal transition.

  18. Are Carotid Stent Fractures Clinically Significant?

    SciTech Connect

    Garcia-Toca, Manuel; Rodriguez, Heron E.; Naughton, Peter A.; Keeling, Aiofee; Phade, Sachin V.; Morasch, Mark D.; Kibbe, Melina R.; Eskandari, Mark K.

    2012-04-15

    Purpose: Late stent fatigue is a known complication after carotid artery stenting (CAS) for cervical carotid occlusive disease. The purpose of this study was to determine the prevalence and clinical significance of carotid stent fractures. Materials and Methods: A single-center retrospective review of 253 carotid bifurcation lesions treated with CAS and mechanical embolic protection from April 2001 to December 2009 was performed. Stent integrity was analyzed by two independent observers using multiplanar cervical plain radiographs with fractures classified into the following types: type I = single strut fracture; type II = multiple strut fractures; type III = transverse fracture; and type IV = transverse fracture with dislocation. Mean follow-up was 32 months. Results: Follow-up imaging was completed on 106 self-expanding nitinol stents (26 closed-cell and 80 open-cell stents). Eight fractures (7.5%) were detected (type I n = 1, type II n = 6, and type III n = 1). Seven fractures were found in open-cell stents (Precise n = 3, ViVEXX n = 2, and Acculink n = 2), and 1 fracture was found in a closed-cell stent (Xact n = 1) (p = 0.67). Only a previous history of external beam neck irradiation was associated with fractures (p = 0.048). No associated clinical sequelae were observed among the patients with fractures, and only 1 patient had an associated significant restenosis ({>=}80%) requiring reintervention. Conclusions: Late stent fatigue after CAS is an uncommon event and rarely clinically relevant. Although cell design does not appear to influence the occurrence of fractures, lesion characteristics may be associated risk factors.

  19. Thin film nitinol covered stents: design and animal testing.

    PubMed

    Levi, Daniel S; Williams, Ryan J; Liu, Jasen; Danon, Saar; Stepan, Lenka L; Panduranga, Mohanchandra K; Fishbein, Michael C; Carman, Greg P

    2008-01-01

    Interventionalists in many specialties have the need for improved, low profile covered stents. Thin films of nitinol (<5-10 microns) could be used to improve current covered stent technology. A "hot target" sputter deposition technique was used to create thin films of nitinol for this study. Covered stents were created from commercially available balloon-inflatable and self-expanding stents. Stents were deployed in a laboratory flow loop and in four swine. Uncovered stent portions served as controls. Postmortem examinations were performed 2-6 weeks after implantation. In short-term testing, thin film nitinol covered stents deployed in the arterial circulation showed no intimal proliferation and were easily removed from the arterial wall postmortem. Scanning electron microscopy showed a thin layer of endothelial cells on the thin film, which covered the entire film by 3 weeks. By contrast, significant neointimal hyperplasia occurred on the luminal side of stents deployed in the venous circulation. Extremely low-profile covered stents can be manufactured using thin films of nitinol. Although long-term studies are needed, thin film nitinol may allow for the development of low-profile, nonthrombogenic covered stents.

  20. Should plastic stents be avoided in all unresectable malignant perihilar biliary strictures?

    PubMed

    Kawashima, Hiroki; Itoh, Akihiro; Ohno, Eizaburo; Goto, Hidemi; Hirooka, Yoshiki

    2013-05-01

    Clinical guidelines of the European Society of Gastrointestinal Endoscopy recommend the insertion of self-expandable metallic stents (SEMS) as opposed to plastic stents (PS) in patients with unresectable malignant perihilar stricture (MHS). However, PS are cheaper and easier to insert into the biliary duct compared to SEMS. Furthermore, PS are removable and easy to move into subsequent drainage procedures. We conducted the present retrospective single-center study to elucidate the predictive factors associated with stent patency period duration in patients with unresectable MHS who would benefit from a long patency period after PS placement. This study included 56 consecutive patients with unresectable MHS who were drained using PS. PS failure occurred in 26 (46.4%) patients. The median patency period was 72 days (95% confidence interval: 29.8-114). The only significant predictive factor associated with the length of the stent patency period was history of previous endoscopic sphincterotomy (EST). Median patency periods with and without previous EST were 28 and 109 days, respectively (P = 0.016). In conclusion, we suggest that conventional biliary drainage with PS is still a suitable option for the treatment of unresectable MHS in patients without previous EST.

  1. Fully biodegradable coronary stents : progress to date.

    PubMed

    Ramcharitar, Steve; Serruys, Patrick W

    2008-01-01

    The limitations of currently available metallic drug-eluting stents have renewed interest in biodegradable stents (BDS). Apart from removing the (offending) foreign material that may potentiate a thrombotic event, BDS have the advantage of avoiding 'full metal jackets,' and thus can preclude subsequent coronary surgery. In addition, they do not interfere with the diagnostic evaluation of non-invasive imaging such as cardiac magnetic resonance and CT. There are now several BDS in development or in clinical trials that incorporate a variety of biodegradable polymer technologies. Two broad categories of materials are generally used: those made from organic biopolymers and those made from corrodible metals. However, to date, none of the materials/stents tested have been able to establish a perfect balance between biocompatibility, the kinetics of degradation needed to maintain mechanical strength to limit recoil, and inflammation. However, studies, such as the ABSORB trial with the everolimus eluting poly-L-lactide stent, which demonstrated comparable restenotic rates with bare metallic stents and a low incidence of major adverse cardiac events (MACE) at 12 months of 3.3%, with only one patient having a non-Q-wave myocardial infarction and no target lesion revascularization, suggest that there has been significant progress with respect to the earlier prototypes. The acute recoil observed could potentially be addressed with the polytyrosine REVA stent currently being evaluated in the RESORB trial, which incorporates a novel locking mechanism within its design. Alternative BDS designs include the combination of an antiproliferative drug with endothelial progenitor cell capturing antibodies to facilitate epithelialization and/or dual eluting having, in addition to the antiproliferative drug, polymeric salicyclic acid to limit inflammation. Compared with biodegradable polymers, there are fewer metals used in the manufacture of BDS. The only metal BDS in trials is the

  2. Simultaneous Thrombosis of Two Drug-Eluting Stents After Discontinuation of Dual Antiplatelet Therapy for a Day

    PubMed Central

    Chen, Hung Yi

    2012-01-01

    Stent thrombosis is rare but can lead to potential severe consequence. The incidence is relative higher in drug-eluting sent than bare-metal stent implantation. Dual antiplatelet therapy is the major treatment to avoid early and late stent thrombosis. Simultaneous two stents thrombosis is rare. Although mechanical or/and procedure factors may predispose to stent thrombosis occurred, simultaneous two stents thrombosis implies possibly ineffective antiplatelet therapy. We report a case with simultaneous two stent thrombosis and complicated with cardiogenic shock after lost antiplatelet therapy for one day. We try to emphasize to properly educate patients about the importance of continuous drug use to avoid catastrophic tragedy.

  3. Palliative stenting for relief of dysphagia in patients with inoperable esophageal cancer: impact on quality of life.

    PubMed

    Madhusudhan, Chinthakandhi; Saluja, Sundeep S; Pal, Sujoy; Ahuja, Vineet; Saran, Pratap; Dash, Nihar R; Sahni, Peush; Chattopadhyay, Tushar K

    2009-01-01

    The aim of palliation in patients with inoperable esophageal cancer is to relieve dysphagia with minimal morbidity and mortality, and thus improve quality of life (QOL). The use of a self-expanding metal stent (SEMS) is a well-established modality for palliation of dysphagia in such patients. We assessed the QOL after palliative stenting in patients with inoperable esophageal cancer. Thirty-three patients with dysphagia due to inoperable esophageal cancer underwent SEMS insertion between October 2004 and December 2006. All patients had grade III/IV dysphagia and locally advanced unresectable cancer (n = 13), distant metastasis (n = 14), or comorbid conditions/poor general health status precluding a major surgical procedure (n = 6). Patients with grade I/II dysphagia and those with carcinoma of the cervical esophagus were excluded. The QOL was assessed using the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 (version 3) and EORTC QLQ-Esophagus (OES) 18 questionnaire (a QOL scale specifically designed for esophageal diseases) before and at 1, 4, and 8 weeks after placement of the stent. The mean age of the patients was 56 (range 34-78) years, and 22 were men. A covered SEMS was used in all patients. The most common site of malignancy was the lower third of the esophagus (n = 18, 55%). In 23 (77%) patients, the stent crossed the gastroesophageal junction. Seven patients required a reintervention for stent block (n = 5) and stent migration (n = 2). Dysphagia improved significantly immediately after stenting, and this improvement persisted until 8 weeks (16.5 vs. 90.6; P < 0.01). The global health status (5.8 vs. 71.7; P < 0.01) and all functional scores improved significantly after stenting from baseline until 8 weeks. Except pain (14.1 vs. 17.7; P = 0.67), there was significant improvement in deglutition (22.7 vs. 2.0; P < 0.01), eating (48 vs. 12.6; P < 0.01), and other symptom scales (19.7 vs. 12.1; P = 0.04) following stenting. The

  4. Successful use of glycoprotein IIb/IIIa inhibitor, heparin, and IABP during PCI in a post-neurosurgical patient with STEMI and cardiogenic shock due to very late bare-metal stent thrombosis.

    PubMed

    Akkus, Nuri I; Rajpal, Saurabh; Agnani, Sujata

    2012-02-01

    Stent thrombosis is not unusual in a post-operative setting. Use of heparin, aspirin, clopidogrel, and glycoprotein (GP) IIb/IIIa inhibitors in this setting needs to be balanced because of the increased risk of perioperative bleeding. This is of special concern in neurosurgery, where postoperative mass effect from bleeding in a closed space is a serious risk. We describe a unique case of inferior and anterior ST-elevation myocardial infarction in cardiogenic shock during spinal surgery with acute, very late bare-metal stent (BMS) thrombosis in the left anterior descending coronary artery and simultaneous acute thrombotic occlusion of the right coronary artery, treated by primary percutaneous intervention, intra-aortic balloon pump (IABP) support and use of GP IIb/IIIa inhibitor in addition to clopidogrel, aspirin, and heparin with good surgical and cardiac outcome. This case report describes first time use of GP IIb/IIIa inhibitor and IABP with heparin, in a patient just after spinal surgery.

  5. Expanding metal mixture toxicity models to natural stream and lake invertebrate communities.

    PubMed

    Balistrieri, Laurie S; Mebane, Christopher A; Schmidt, Travis S; Keller, Wendel Bill

    2015-04-01

    A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biological receptors (biotic ligands). These models differ in the structure of the receptors and include a 2-site biotic ligand model, a bidentate biotic ligand or 2-pKa model, and a humic acid model. The predicted accumulation of toxicants is weighted using toxicant-specific coefficients and incorporated into a toxicity function called Tox, which is then related to observed mortality or invertebrate community richness using a logistic equation. All accumulation models provide reasonable fits to metal concentrations in tissue samples of stream invertebrates. Despite the good fits, distinct differences in the magnitude of toxicant accumulation and biotic ligand speciation exist among the models for a given solution composition. However, predicted biological responses are similar among the models because there are interdependencies among model parameters in the accumulation-Tox models. To illustrate potential applications of the approaches, the 3 accumulation-Tox models for natural stream invertebrates are used in Monte Carlo simulations to predict the probability of adverse impacts in catchments of differing geology in central Colorado (USA); to link geology, water chemistry, and biological response; and to demonstrate how this approach can be used to screen for potential risks associated with resource development.

  6. Expanding metal mixture toxicity models to natural stream and lake invertebrate communities

    USGS Publications Warehouse

    Balistrieri, Laurie S.; Mebane, Christopher A.; Schmidt, Travis S.; Keller, William (Bill)

    2015-01-01

    A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biological receptors (biotic ligands). These models differ in the structure of the receptors and include a 2-site biotic ligand model, a bidentate biotic ligand or 2-pKa model, and a humic acid model. The predicted accumulation of toxicants is weighted using toxicant-specific coefficients and incorporated into a toxicity function called Tox, which is then related to observed mortality or invertebrate community richness using a logistic equation. All accumulation models provide reasonable fits to metal concentrations in tissue samples of stream invertebrates. Despite the good fits, distinct differences in the magnitude of toxicant accumulation and biotic ligand speciation exist among the models for a given solution composition. However, predicted biological responses are similar among the models because there are interdependencies among model parameters in the accumulation–Tox models. To illustrate potential applications of the approaches, the 3 accumulation–Tox models for natural stream invertebrates are used in Monte Carlo simulations to predict the probability of adverse impacts in catchments of differing geology in central Colorado (USA); to link geology, water chemistry, and biological response; and to demonstrate how this approach can be used to screen for potential risks associated with resource development.

  7. iStent trabecular micro-bypass stent for open-angle glaucoma

    PubMed Central

    Le, Kim; Saheb, Hady

    2014-01-01

    Trabecular micro-bypass stents, commonly known as iStents, are micro-invasive glaucoma surgery (MIGS) devices used to treat open-angle glaucoma. Like other MIGS procedures that enhance trabecular outflow, the iStent lowers intraocular pressure (IOP) by creating a direct channel between the anterior chamber and Schlemm’s canal. iStents are typically implanted at the time of phacoemulsification for patients with open-angle glaucoma and visually significant cataracts. This review summarizes the published data regarding the efficacy, safety, and cost considerations of trabecular micro-bypass stents. Most studies found statistically significant reductions in mean IOP and ocular medication use after combined phacoemulsification with single or double iStent implantation. The devices were found to be very safe, with a safety profile similar to that of cataract surgery. Complications were infrequent, with the most common complications being temporary stent obstruction or malposition, which resolved with observation or secondary procedures. Future studies are needed to evaluate long-term outcomes, patient satisfaction, cost effectiveness, and expanded indications. PMID:25284980

  8. [Magnetic resonance compatibility research for coronary mental stents].

    PubMed

    Wang, Ying; Liu, Li; Wang, Shuo; Shang, Ruyao; Wang, Chunren

    2015-01-01

    The objective of this article is to research magnetic resonance compatibility for coronary mental stents, and to evaluate the magnetic resonance compatibility based on laboratory testing results. Coronary stents magnetic resonance compatibility test includes magnetically induced displacement force test, magnetically induced torque test, radio frequency induced heating and evaluation of MR image. By magnetic displacement force and torque values, temperature, and image distortion values to determine metal coronary stent demagnetization effect. The methods can be applied to test magnetic resonance compatibility for coronary mental stents and evaluate its demagnetization effect.

  9. The MGuard coronary stent: safety, efficacy, and clinical utility

    PubMed Central

    Gracida, Montserrat; Romaguera, Rafael; Jacobi, Francisco; Gómez-Hospital, Joan A; Cequier, Angel

    2015-01-01

    Atheromatous and thrombotic embolization during percutaneous coronary revascularization is a feared complication that may cause impaired myocardial reperfusion even with a patent epicardial vessel. The MGuard stent is a cobalt chromium bare metal stent with a porous net attached to its outer surface that has been designed to prevent thrombus fragmentation and distal embolization during stent implantation. This review summarizes the available evidence supporting the use of the MGuard stent in different scenarios such as lesions with high thrombus burden, saphenous vein graft interventions, coronary perforations, or carotid lesions. PMID:26425097

  10. Coronary stenting: A matter of revascularization

    PubMed Central

    Bonaventura, Aldo; Montecucco, Fabrizio; Liberale, Luca

    2017-01-01

    In the last few decades, the recommended treatment for coronary artery disease has been dramatically improved by percutaneous coronary intervention (PCI) and the use of balloon catheters, bare metal stents (BMSs), and drug-eluting stents (DESs). Catheter balloons were burdened by acute vessel occlusion or target-lesion re-stenosis. BMSs greatly reduced those problems holding up the vessel structure, but showed high rates of in-stent re-stenosis, which is characterized by neo-intimal hyperplasia and vessel remodeling leading to a re-narrowing of the vessel diameter. This challenge was overtaken by first-generation DESs, which reduced re-stenosis rates to nearly 5%, but demonstrated delayed arterial healing and risk for late in-stent thrombosis, with inflammatory cells playing a pivotal role. Finally, new-generation DESs, characterized by innovations in design, metal composition, surface polymers, and anti-proliferative drugs, finally reduced the risk for stent thrombosis and greatly improved revascularization outcomes. New advances include bioresorbable stents potentially changing the future of revascularization techniques as the concept bases upon the degradation of the stent scaffold to inert particles after its function expired, thus theoretically eliminating risks linked with both stent thrombosis and re-stenosis. Talking about DESs also dictates to consider dual antiplatelet therapy (DAPT), which is a fundamental moment in view of the good outcome duration, but also deals with bleeding complications. The better management of patients undergoing PCI should include the use of DESs and a DAPT finely tailored in consideration of the potentially developing bleeding risk in accordance with the indications from last updated guidelines.

  11. Black hole restenosis after drug-eluting stent implantation for in-stent restenosis: potential mechanism and optimal strategy.

    PubMed

    Otsuka, Yoritaka; Murata, Takashi; Kono, Michiaki; Imoto, Hiroki; Koyama, Taku; Nakamura, Keita; Kadama, Sunao; Noguchi, Hiroo; Saito, Taro

    2015-09-01

    In-stent restenosis (ISR) has long remained as the major limitation of coronary stenting. The use of drug-eluting stent (DES) reduces the risk of repeat revascularization without an increase of death and myocardial infarction, compared to the standard bare metal stents. DES has also demonstrated markedly to reduce ISR for complex lesions. However, ISR after DES implantation still occurs and optimal treatment for ISR after DES has not been established. Herein, we report 3 cases with black hole restenosis confirmed by intravascular ultrasound at the site of overlapped DES and discuss potential mechanism and optimal strategy for this phenomenon.

  12. Percutaneous Transhepatic Biliary Metal Stent for Malignant Hilar Obstruction: Results and Predictive Factors for Efficacy in 159 Patients from a Single Center

    SciTech Connect

    Li, Mingwu Bai, Ming Qi, Xingshun Li, Kai Yin, Zhanxin; Wang, Jianhong; Wu, Wenbing Zhen, Luanluan He, Chuangye; Fan, Daiming; Zhang, Zhuoli; Han, Guohong E-mail: Hangh@fmmu.edu.cn

    2015-06-15

    AimTo investigate and compare the efficacy and safety of percutaneous transhepatic biliary stenting (PTBS) using a one- or two-stage procedure and determine the predictive factors for the efficacious treatment of malignant hilar obstruction (MHO).Methods159 consecutive patients with MHO who underwent PTBS were enrolled between January 2010 and June 2013. Patients were classified into one- or two-stage groups. Independent predictors of therapeutic success were evaluated using a logistic regression model.Results108 patients were treated with one-stage PTBS and 51 patients were treated with two-stage PTBS. The stents were technically successful in all patients. Successful drainage was achieved in 114 patients (71.4 %). A total of 42 early major complications were observed. Re-interventions were attempted in 23 patients during follow-up. The cumulative primary patency rates at 3, 6, and 12 months were 88, 71, and 48 %, respectively. Stent placement using a one- or two-stage procedure did not significantly affect therapeutic success, early major complications, median stent patency, or survival. A stent placed across the duodenal papilla was an independent predictor of therapeutic success (odds ratio = 0.262, 95 % confidence interval [0.107–0.642]). Patients with stents across papilla had a lower rate of cholangitis compared with patients who had a stent above papilla (7.1 vs. 20.3 %, respectively, p = 0.03).ConclusionsThe majority of patients with MHO who underwent one-stage PTBS showed similar efficacy and safety outcomes compared with those who underwent two-stage PTBS. Stent placement across the duodenal papilla was associated with a higher therapeutic success rate.

  13. Transcatheter retrieval and repositioning of embolized stent from the right ventricle in an infant.

    PubMed

    Kobayashi, Daisuke; Singh, Harinder R; Turner, Daniel R; Forbes, Thomas J; Gowda, Srinath T

    2012-01-01

    Intracardiac stent embolization is a challenging complication in a small infant. A Palmaz stent was placed across the atrial septum in a 3-month-old boy to relieve symptoms of right-side heart failure. On routine chest radiography one week later, the stent was found to have embolized into the right ventricle. The stent was retrieved and repositioned by means of transcatheter technique, without subsequent complications. We found this method to be a viable alternative to surgery in a high-risk infant. To our knowledge, this is the first report of the successful transcatheter retrieval and repositioning of an expandable intravascular stent from an intraventricular position in an infant.

  14. The role of stents in the treatment of Crohn’s disease strictures

    PubMed Central

    Loras Alastruey, Carme; Andújar Murcia, Xavier; Esteve Comas, Maria

    2016-01-01

    Background and aims: Stenosis is one of the most frequent local complications in Crohn’s disease (CD). Surgery is not the ideal treatment because of the high rate of postoperative recurrence. Endoscopic balloon dilation (EBD) currently is the current treatment of choice for short strictures amenable to the procedure. However, it is not applicable or effective in all the cases, and it is not without related complications. Our goal was to summarize the published information regarding the use and the role of the stents in the treatment of CD stricture. A Medline search was performed on the terms “stricture,” “stenosis,” “stent” and “Crohn’s disease.” Results: a total of 19 publications met our search criteria for an overall number of 65 patients. Placing a self-expanding metal stent (SEMS) may be a safe and effective alternative to EBD and/or surgical intervention in the treatment of short stenosis in patients with CD. Indications are the same as those for EBD. In addition, SEMS may be useful in stenosis refractory to EBD and may be suitable in the treatment of longer or more complex strictures that cannot be treated by EBD. With the current information, it seems that the best treatment option is the placement of a fully covered stent for a mean time of 4 weeks. Regarding the use of biodegradable stents, the information is limited and showing poor results. Conclusions: the use of stents in the treatment of strictures in CD should be taken into account either as a first endoscopic therapy or in case of EBD failure. PMID:27014743

  15. Research of Customized Aortic Stent Graft Manufacture

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Chen, Xin; Liu, Muhan

    2017-03-01

    Thoracic descending aorta diseases include aortic dissection and aortic aneurysm, of which the natural mortality rate is extremely high. At present, endovascular aneurysm repair (EVAR) has been widely used as an effective means for the treatment of descending aortic disease. Most of the existing coating stents are standard design, which are unable to meet the size or structure of different patients. As a result, failure of treatment would be caused by dimensional discrepancy between stent and vessels, which could lead to internal leakage or rupture of blood vessels. Therefore, based on rapid prototyping sacrificial core – coating forming (RPSC-CF), a customized aortic stent graft manufactured technique has been proposed in this study. The aortic stent graft consists of film and metallic stent, so polyether polyurethane (PU) and nickel-titanium (NiTi) shape memory alloy with good biocompatibility were chosen. To minimum film thickness without degrading performance, effect of different dip coating conditions on the thickness of film were studied. To make the NiTi alloy exhibit super-elasticity at body temperature (37°C), influence of different heat treatment conditions on austenite transformation temperature (Af) and mechanical properties were studied. The results show that the customized stent grafts could meet the demand of personalized therapy, and have good performance in blasting pressure and radial support force, laying the foundation for further animal experiment and clinical experiment.

  16. Second- and third-generation drug-eluting coronary stents: progress and safety.

    PubMed

    Akin, I; Schneider, H; Ince, H; Kische, S; Rehders, T C; Chatterjee, T; Nienaber, C A

    2011-05-01

    Drug-eluting stents (DES) have revolutionized the treatment of coronary artery disease by reducing the rate of in-stent restenosis from 20-40% with bare-metal stent (BMS) to 6-8% with DES. However, with widespread use of DES, safety concerns have risen due to the observation of late stent thrombosis. With this in mind and better understanding of mechanism and pathophysiology of stent thrombosis, the technological platform, especially innovative anti-restenotic agents, polymeric coatings, and stent platforms, improved with newer DES. Two second-generation DES, the Endeavor zotarolimus-eluting stent (ZES) and the Xience-V everolimus-eluting stent (EES), have provided promising results in both randomized controlled trials (SPIRIT and ENDEAVOR) and registries (E-Five, COMPARE) compared with bare-metal stents (BMS) and first-generation DES. Newer third-generation stent technology, especially biodegradable polymers, polymer-free stents, and biodegradable stents on the basis of poly-L-lactide (PLLA) or magnesium, has been evaluated in preclinical and initial clinical trials. However, despite encouraging initial results, long-term data of large-scale randomized trials as well as registries comparing them to currently approved first- and second-generation DES are still lacking.

  17. Angioscopic Evaluation of Neointimal Coverage of Coronary Stents.

    PubMed

    Uchida, Yasumi; Uchida, Yasuto

    2010-10-01

    Drug-eluting stents (DES) reduce coronary restenosis significantly; however, late stent thrombosis (LST) occurs, which requires long-term antiplatelet therapy. Angioscopic grading of neointimal coverage of coronary stent struts was established, and it was revealed that neointimal formation is incomplete and prevalence of LST is higher in DES when compared to bare-metal stents. It was also observed that the neointima is thicker and LST is less frequent in paclitaxel-eluting and zotarolimus-eluting stents than in sirolimus-eluting stents. Many new stents were devised and they are now under experimental or clinical investigations to overcome the shortcomings of the stents that have been employed clinically. Endothelial cells are highly anti-thrombotic. Neo-endothelial cell damage is considered to be caused by friction between the cells and stent struts due to the thin neointima between them which might act as a cushion. Therefore, development of a DES that causes an appropriate thickness (around 100 μm) of the neointima is a potential option with which to prevent neo-endothelial cell damage and consequent LST while preventing restenosis.

  18. A review on biodegradable materials for cardiovascular stent application

    NASA Astrophysics Data System (ADS)

    Hou, Li-Da; Li, Zhen; Pan, Yu; Sabir, MuhammadIqbal; Zheng, Yu-Feng; Li, Li

    2016-09-01

    A stent is a medical device designed to serve as a temporary or permanent internal scaffold to maintain or increase the lumen of a body conduit. The researchers and engineers diverted to investigate biodegradable materials due to the limitation of metallic materials in stent application such as stent restenosis which requires prolonged anti platelet therapy, often result in smaller lumen after implantation and obstruct re-stenting treatments. Biomedical implants with temporary function for the vascular intervention are extensively studied in recent years. The rationale for biodegradable stent is to provide the support for the vessel in predicted period of time and then degrading into biocompatible constituent. The degradation of stent makes the re-stenting possible after several months and also ameliorates the vessel wall quality. The present article focuses on the biodegradable materials for the cardiovascular stent. The objective of this review is to describe the possible biodegradable materials for stent and their properties such as design criteria, degradation behavior, drawbacks and advantages with their recent clinical and preclinical trials.

  19. Lethal Hemorrhage Caused by Aortoenteric Fistula Following Endovascular Stent Implantation

    SciTech Connect

    Kahlke, Volker; Brossmann, Joachim; Klomp, Hans-Juergen

    2002-06-15

    A 55-year-old women developed an aortointestinal fistula between the bifurcation of the aorta and the distal ileum following implantation of multiple endovascular stents into both common iliac arteries for treatment of aortoiliac occlusive disease. Ten months before the acute onset of the gastrointestinal hemorrhage two balloon-expandable steel stents had been implanted into both common iliac arteries. Due to restenosis and recurrent intermittent claudication, three balloon-expandable covered stents were implanted 4 months later on reintervention. The patient presented with abdominal pain and melena, and fell into hemorrhagic shock with signs of upper gastrointestinal bleeding. After transfer to our hospital, she again developed hemorrhagic shock with massive upper and lower gastrointestinal bleeding and died during emergency laparotomy. The development of aortoenteric fistulas following endovascular surgery/stent implantation is very rare and has to be considered in cases of acute gastrointestinal hemorrhage.

  20. Update in urethral stents.

    PubMed

    Bahouth, Z; Meyer, G; Yildiz, G; Nativ, O; Moskovitz, B

    2016-10-01

    Urethral stents were first introduced in 1988, and since then, they have undergone significant improvements. However, they did not gain a wide popularity and their use is limited to a small number of centers around the world. Urethral stents can be used in the entire urethra and for various and diverse indications. In the anterior urethra, it can be used to treat urethral strictures. In the prostatic urethra, they can be used for the treatment of prostatic obstruction, including benign, malignant and iatrogenic prostatic obstruction. Moreover, although not widely used, it can be also applied for the treatment of posterior urethral stricture and bladder neck contracture, usually resulting in urinary incontinence and the need for subsequent procedures. Our main experience are with Allium urethral stents, and as such, we provide the latest updates in urethral stents with special emphasis on the various types of Allium urethral stents: bulbar, prostatic and bladder neck stents.

  1. Titanium-nitride-oxide-coated coronary stents: insights from the available evidence.

    PubMed

    Karjalainen, Pasi P; Nammas, Wail

    2016-11-12

    Coating of stent surface with a biocompatible material is suggested to improve stent safety profile. A proprietary process was developed to coat titanium-nitride-oxide on the stent surface, based on plasma technology that uses the nano-synthesis of gas and metal. Preclinical in vitro and in vivo investigation confirmed blood compatibility of titanium (nitride-) oxide films. Titanium-nitride-oxide-coated stents demonstrated a better angiographic outcome, compared with bare-metal stents at mid-term follow-up; however, they failed to achieve non-inferiority for angiographic outcome versus second-generation drug-eluting stents. Observational studies showed adequate clinical outcome at mid-term follow-up. Non-randomized studies showed an outcome of titanium-nitride-oxide-coated stents comparable to - or better than - first-generation drug-eluting stents at long-term follow-up. Two randomized controlled trials demonstrated comparable efficacy outcome, and a better safety outcome of titanium-nitride-oxide-coated stents versus drug-eluting stents at long-term follow-up. Evaluation by optical coherence tomography at mid-term follow-up revealed better neointimal strut coverage associated with titanium-nitride-oxide-coated stents versus drug-eluting stents; yet, neointimal hyperplasia thickness was greater. Key messages Stents coated with titanium-nitride-oxide demonstrated biocompatibility in preclinical studies: they inhibit platelet and fibrin deposition, and reduce neointimal growth. In observational and non-randomized studies, titanium-nitride-oxide-coated stents were associated with adequate safety and efficacy outcome. In randomized trials of patients with acute coronary syndrome, titanium-nitride-oxide-coated stents were associated with a better safety outcome, compared with drug-eluting stents; efficacy outcome was comparable.

  2. High Fidelity Virtual Stenting (HiFiVS) for Intracranial Aneurysm Flow Diversion: In Vitro and In Silico

    PubMed Central

    Ma, Ding; Dumont, Travis M.; Kosukegawa, Hiroyuki; Ohta, Makoto; Yang, Xinjian; Siddiqui, Adnan H.; Meng, Hui

    2013-01-01

    A flow diverter (FD) is a flexible, densely braided stent-mesh device placed endoluminally across an intracranial aneurysm to induce its thrombotic occlusion. FD treatment planning using computational virtual stenting and flow simulation requires accurate representation of the expanded FD geometry. We have recently developed a High Fidelity Virtual Stenting (HiFiVS) technique based on finite element analysis to simulate detailed FD deployment processes in patient-specific aneurysms (Ma et al. J. Biomech. 45: 2256–2263, 2012). This study tests if HiFiVS simulation can recapitulate real-life FD implantation. We deployed two identical FDs (Pipeline Embolization Device) into phantoms of a wide-necked segmental aneurysm using a clinical push-pull technique with different delivery wire advancements. We then simulated these deployment processes using HiFiVS and compared results against experimental recording. Stepwise comparison shows that the simulations precisely reproduced the FD deployment processes recorded in vitro. The local metal coverage rate and pore density quantifications demonstrated that simulations reproduced detailed FD mesh geometry. These results provide validation of the HiFiVS technique, highlighting its unique capability of accurately representing stent intervention in silico. PMID:23604850

  3. [Advantages of endoscopic stenting for malignant gastrointestinal obstructions].

    PubMed

    Meier, P N; Manns, M P

    2006-03-01

    Self-expanding stents play a major role in the interdisciplinary treatment of gastrointestinal obstructions in patients with local nonresectable tumors, advanced metastasis, and pronounced comorbidity. Reinstenting the passage and sealing esophagotracheal fistulae is very effective as palliative treatment for esophageal tumor complications. In hepatobiliary occlusions, the success rate against cholestasis is also high. Enteral and colorectal stents are gaining favor. Required are an experienced endoscopy team and adequate equipment. The rate of procedural complications is generally low, but rare and severe complications such as perforation must be considered. Further improvements in the materials and construction of stents can be expected.

  4. Stenting in the Treatment of Acute Ischemic Stroke: Literature Review

    PubMed Central

    Samaniego, Edgar A.; Dabus, Guilherme; Linfante, Italo

    2011-01-01

    Recanalization of acute large artery occlusions is a strong predictor of good outcome. The development of thrombectomy devices resulted in a significant improvement in recanalization rates compared to thrombolytics alone. However, clinical trials and registries with these thrombectomy devices in acute ischemic stroke (AIS) have shown recanalization rates in the range of 40–81%. The last decade has seen the development of nickel titanium self-expandable stents (SES). These stents, in contrast to balloon-mounted stents, allow better navigability and deployment in tortuous vessels and therefore are optimal for the cerebral circulation. SES were initially used for stent-assisted coil embolization of intracranial aneurysms and for treatment of intracranial stenosis. However, a few authors have recently reported feasibility of deployment of SES in AIS. The use of these devices yielded higher recanalization rates compared to traditional thrombectomy devices. Encouraged by these results, retrievable SES systems have been recently used in AIS. These devices offer the advantage of resheathing and retrieving of the stent even after full deployment. Some of these stents can also be detached in case permanent stent placement is needed. Retrievable SES are being used in Europe and currently tested in clinical trials in the United States. We review the recent literature in the use of stents for the treatment of AIS secondary to large vessel occlusion. PMID:22163225

  5. Thermomechanical Properties, Collapse Pressure, and Expansion of Shape Memory Polymer Neurovascular Stent Prototypes

    PubMed Central

    Baer, Géraldine M.; Wilson, Thomas S.; Small, Ward; Hartman, Jonathan; Benett, William J.; Matthews, Dennis L.; Maitland, Duncan J.

    2011-01-01

    Shape memory polymer stent prototypes were fabricated from thermoplastic polyurethane. Commercial stents are generally made of stainless steel or other alloys. These alloys are too stiff and prevent most stent designs from being able to navigate small and tortuous vessels to reach intracranial lesions. A solid tubular model and a high flexibility laser etched model are presented. The stents were tested for collapse in a pressure chamber. At 37°C, the full collapse pressure was comparable to that of commercially available stents, and higher than the estimated maximum pressure exerted by intracranial arteries. However, there is a potential for onset of collapse, which needs further study. The stents were crimped and expanded, the laser-etched stent showed full recovery with an expansion ratio of 2.7 and a 1% axial shortening. PMID:19107804

  6. Expandable and retractable self-rolled structures based on metal/polymer thin film for flow sensing

    NASA Astrophysics Data System (ADS)

    Zhu, Jianzhong; White, Carl; Saadat, Mehdi; Bart-Smith, Hilary

    2015-11-01

    Most aquatic animals such as fish rely heavily on their ability of detect and respond to ambient flows in order to explore and inhabit various habitats or survive predator-prey encounters. Fish utilize neuromasts in their skin surface and lateral lines in their bodies to align themselves while swimming upstream for migration, avoid obstacles, reduce locomotion cost, and detect flow variations caused by potential predators. In this study, a thin film MEMS sensor analogous to a fish neuromast has been designed for flow sensing. Residual stress arises in many thin film materials during processing. Metal and polymer thin film materials with a significant difference in elastic modular were chosen to form a multiple-layer structure. Upon releasing, the structure rolls into a tube due to mechanical property mismatch. The self-rolled tube can expand or retract, depending on the existence of external force such as flow. An embedded strain sensor detects the deformation of the tube and hence senses the ambient flow. Numerical simulations were conducted to optimize the structural design. Experiments were performed in a flow tank to quantify the performance of the sensor. This research is supported by the Office of Naval Research under the MURI Grant N00014-14-1-0533.

  7. Static, dynamic and electronic properties of expanded fluid mercury in the metal-nonmetal transition range. An ab initio study.

    PubMed

    Calderín, L; González, L E; González, D J

    2011-09-21

    Fluid Hg undergoes a metal-nonmetal (M-NM) transition when expanded toward a density of around 9 g cm(-3). We have performed ab initio molecular dynamics simulations for several thermodynamic states around the M-NM transition range and the associated static, dynamic and electronic properties have been analyzed. The calculated static structure shows a good agreement with the available experimental data. It is found that the volume expansion decreases the number of nearest neighbors from 10 (near the triple point) to around 8 at the M-NM transition region. Moreover, these neighbors are arranged into two subshells and the decrease in the number of neighbors occurs in the inner subshell. The calculated dynamic structure factors agree fairly well with their experimental counterparts obtained by inelastic x-ray scattering experiments, which display inelastic side peaks. The derived dispersion relation exhibits some positive dispersion for all the states, although its value around the M-NM transition region is not as marked as suggested by the experiment. We have also calculated the electronic density of states, which shows the appearance of a gap at a density of around 8.3 g cm(-3).

  8. The Relationships between Polymorphisms in Genes Encoding the Growth Factors TGF-β1, PDGFB, EGF, bFGF and VEGF-A and the Restenosis Process in Patients with Stable Coronary Artery Disease Treated with Bare Metal Stent

    PubMed Central

    Osadnik, Tadeusz; Strzelczyk, Joanna Katarzyna; Reguła, Rafał; Bujak, Kamil; Fronczek, Martyna; Gonera, Małgorzata; Gawlita, Marcin; Wasilewski, Jarosław; Lekston, Andrzej; Kurek, Anna; Gierlotka, Marek; Trzeciak, Przemysław; Hawranek, Michał; Ostrowska, Zofia; Wiczkowski, Andrzej; Poloński, Lech; Gąsior, Mariusz

    2016-01-01

    VEGF-A genes, respectively, are associated with LLL in patients with SCAD treated by PCI with a metal stent implantation. PMID:26930482

  9. Dissimilar relevance given to diseases by medical literature, and the potential to create biases in the clinical decision-making process: the case of late stent thrombosis.

    PubMed

    Agostoni, Pierfrancesco; Kedhi, Elvin; Verheye, Stefan; Vermeersch, Paul; Van Langenhove, Glenn

    2007-01-08

    We discuss two cases of non-occlusive sub-acute/late stent thrombosis, one correctly diagnosed (with the help of intravascular ultrasound) 12 days after implantation of a sirolimus eluting stent, the other erroneously non recognized 17 days after implantation of a bare metal stent and evolving 6 weeks later in total thrombotic occlusion of the stent itself. We believe that our clinical judgment, accurate in case of sirolimus eluting stent thrombosis, but wrong in case of bare metal stent thrombosis, was largely influenced by the recent literature giving overwhelming attention, in the drug-eluting stent era, to an issue (late stent thrombosis) that was already present but under-considered, also in the bare metal stent era.

  10. Good visibility of TITAN-2 coronary stents demonstrable on cardiac computer tomographic angiography: a report of 2 cases.

    PubMed

    Ong, Paul Jau; Jau, Ong Paul; Ho, Hee Hwa; Hwa, Ho Hee; Jafary, Fahim Haider; Haider, Jafary Fahim; Loh, Kwok Kong; Kong, Loh Kwok; Ooi, Yau Wei; Wei, Ooi Yau; Wong, Chun Pong; Pong, Wong Chun; Foo, David; David, Foo

    2011-09-01

    Numerous studies have sought to assess stent patency by cardiac computer tomographic angiography (CCTA) in comparison with invasive coronary angiography in patients who had undergone percutaneous coronary stenting. Even with newer generation scanners, CCTA has been of limited value in the assessment of the revascularized patient. The main reason being blooming artifact from metallic stents often obscures stent luminal dimension, making the stented segment unassessable. We report on a novel finding of good visibility of TITAN-2 coronary stents demonstrable on CCTA for 2 patients and discuss the possible mechanism and potential implications of this observation.

  11. Virtual Stenting Workflow with Vessel-Specific Initialization and Adaptive Expansion for Neurovascular Stents and Flow Diverters

    PubMed Central

    Xu, Jinhui; Xiang, Jianping; Siddiqui, Adnan; Yang, Xinjian; Li, Haiyun; Meng, Hui

    2016-01-01

    Endovascular intervention using traditional neurovascular stents and densely braided flow diverters (FDs) have become the preferred treatment strategies for traditionally challenging intracranial aneurysms (IAs). Modeling stent and FD deployment in patient-specific aneurysms and its flow modification results prior to the actual intervention can potentially predict the patient outcome and treatment optimization. We present a clinically focused, streamlined virtual stenting workflow that efficiently simulates stent and FD treatment in patient-specific aneurysms based on expanding a simplex mesh structure. The simplex mesh is generated using an innovative vessel-specific initialization technique, which uses the patient’s parent artery diameter to identify the initial position of the simplex mesh inside the artery. A novel adaptive expansion algorithm enables the acceleration of deployment process by adjusting the expansion forces based on the distance of the simplex mesh from the parent vessel. The virtual stenting workflow was tested by modeling the treatment of two patient-specific aneurysms using the Enterprise stent and the Pipeline Embolization Device (commercial FD). Both devices were deployed in the aneurysm models in a few seconds. Computational fluid dynamics analyses of pre- and post-treatment aneurysmal hemodynamics show flow reduction in the aneurysmal sac in treated aneurysms, with the FD diverting more flow than the Enterprise stent. The test results show that this workflow can rapidly simulate clinical deployment of stents and FDs, hence paving the way for its future clinical implementation. PMID:26899135

  12. Application of a mechanobiological simulation technique to stents used clinically.

    PubMed

    Boyle, Colin J; Lennon, Alex B; Prendergast, Patrick J

    2013-03-15

    Many cardiovascular diseases are characterised by the restriction of blood flow through arteries. Stents can be expanded within arteries to remove such restrictions; however, tissue in-growth into the stent can lead to restenosis. In order to predict the long-term efficacy of stenting, a mechanobiological model of the arterial tissue reaction to stress is required. In this study, a computational model of arterial tissue response to stenting is applied to three clinically relevant stent designs. We ask the question whether such a mechanobiological model can differentiate between stents used clinically, and we compare these predictions to a purely mechanical analysis. In doing so, we are testing the hypothesis that a mechanobiological model of arterial tissue response to injury could predict the long-term outcomes of stent design. Finite element analysis of the expansion of three different stent types was performed in an idealised, 3D artery. Injury was calculated in the arterial tissue using a remaining-life damage mechanics approach. The inflammatory response to this initial injury was modelled using equations governing variables which represented tissue-degrading species and growth factors. Three levels of inflammation response were modelled to account for inter-patient variability. A lattice-based model of smooth muscle cell behaviour was implemented, treating cells as discrete agents governed by local rules. The simulations predicted differences between stent designs similar to those found in vivo. It showed that the volume of neointima produced could be quantified, providing a quantitative comparison of stents. In contrast, the differences between stents based on stress alone were highly dependent on the choice of comparison criteria. These results show that the choice of stress criteria for stent comparisons is critical. This study shows that mechanobiological modelling may provide a valuable tool in stent design, allowing predictions of their long

  13. Robot-Assisted Antegrade In-Situ Fenestrated Stent Grafting

    SciTech Connect

    Riga, Celia V. Bicknell, Colin D.; Wallace, Daniel; Hamady, Mohamad; Cheshire, Nicholas

    2009-05-15

    To determine the technical feasibility of a novel approach of in-situ fenestration of aortic stent grafts by using a remotely controlled robotic steerable catheter system in the porcine model. A 65-kg pig underwent robot-assisted bilateral antegrade in-situ renal fenestration of an abdominal aortic stent graft with subsequent successful deployment of a bare metal stent into the right renal artery. A 16-mm iliac extension covered stent served as the porcine aortic endograft. Under fluoroscopic guidance, the graft was punctured with a 20-G customized diathermy needle that was introduced and kept in place by the robotic arm. The needle was exchanged for a 4 x 20 mm cutting balloon before successful deployment of the renal stent. Robot-assisted antegrade in-situ fenestration is technically feasible in a large mammalian model. The robotic system enables precise manipulation, stable positioning, and minimum instrumentation of the aorta and its branches while minimizing radiation exposure.

  14. An expanded family of dysprosium-scandium mixed-metal nitride clusterfullerenes: the role of the lanthanide metal on the carbon cage size distribution.

    PubMed

    Wei, Tao; Liu, Fupin; Wang, Song; Zhu, Xianjun; Popov, Alexey A; Yang, Shangfeng

    2015-04-07

    A large family of dysprosium-scandium (Dy-Sc) mixed-metal nitride clusterfullerenes (MMNCFs), Dy(x)Sc(3-x)N@C2n (x = 1, 2, 2n = 68, 70, 76-86) have been successfully synthesized and isolated. Among these, the C70 and C82-based MMNCFs are two new cages that have never been isolated for MMNCFs. Synthesis of Dy(x)Sc(3-x)N@C2n was accomplished by the "selective organic solid" route using guanidinium thiocyanate as the nitrogen source, and their isolation was fulfilled by recycling HPLC. UV/Vis-NIR spectroscopic study indicates that almost all Dy(x)Sc(3-x)N@C2n MMNCFs are kinetically stable fullerenes with optical band gaps beyond 1 eV. This feature is distinctly different to their counterparts Dy3N@C2n (78≤2n≤88), whose for optical band-gaps are below 1 eV for relatively large cages such as C84 and C86. An FTIR spectroscopic study in combination with DFT calculations enables reasonable assignments of the cage isomeric structures of all isolated Dy(x)Sc(3-x)N@C2n (x = 1, 2, 2n = 68, 70, 76-86) MMNCFs. The carbon cage size distribution of Dy(x)Sc(3-x)N@C2n (2n = 68, 70, 76-86) is compared to the reported Dy3N@C2n (78≤2n≤8) homogeneous NCF and Dy(x)Sc(3-x)N@C2n (78≤2n≤88) MMNCF families, revealing that the medium-sized Dy metal plays a crucial role on the expanded cage size distribution of MMNCFs. As a result, Dy(x)Sc(3-x)N@C2n MMNCFs are the largest MMNCF family reported to date.

  15. Automatic stent strut detection in intravascular OCT images using image processing and classification technique

    NASA Astrophysics Data System (ADS)

    Lu, Hong; Gargesha, Madhusudhana; Wang, Zhao; Chamie, Daniel; Attizani, Guilherme F.; Kanaya, Tomoaki; Ray, Soumya; Costa, Marco A.; Rollins, Andrew M.; Bezerra, Hiram G.; Wilson, David L.

    2013-02-01

    Intravascular OCT (iOCT) is an imaging modality with ideal resolution and contrast to provide accurate in vivo assessments of tissue healing following stent implantation. Our Cardiovascular Imaging Core Laboratory has served >20 international stent clinical trials with >2000 stents analyzed. Each stent requires 6-16hrs of manual analysis time and we are developing highly automated software to reduce this extreme effort. Using classification technique, physically meaningful image features, forward feature selection to limit overtraining, and leave-one-stent-out cross validation, we detected stent struts. To determine tissue coverage areas, we estimated stent "contours" by fitting detected struts and interpolation points from linearly interpolated tissue depths to a periodic cubic spline. Tissue coverage area was obtained by subtracting lumen area from the stent area. Detection was compared against manual analysis of 40 pullbacks. We obtained recall = 90+/-3% and precision = 89+/-6%. When taking struts deemed not bright enough for manual analysis into consideration, precision improved to 94+/-6%. This approached inter-observer variability (recall = 93%, precision = 96%). Differences in stent and tissue coverage areas are 0.12 +/- 0.41 mm2 and 0.09 +/- 0.42 mm2, respectively. We are developing software which will enable visualization, review, and editing of automated results, so as to provide a comprehensive stent analysis package. This should enable better and cheaper stent clinical trials, so that manufacturers can optimize the myriad of parameters (drug, coverage, bioresorbable versus metal, etc.) for stent design.

  16. Coronary Stent Materials and Coatings: A Technology and Performance Update.

    PubMed

    O'Brien, Barry; Zafar, Haroon; Ibrahim, Ahmad; Zafar, Junaid; Sharif, Faisal

    2016-02-01

    This paper reviews the current state of the art for coronary stent materials and surface coatings, with an emphasis on new technologies that followed on from first-generation bare metal and drug-eluting stents. These developments have been driven mainly by the need to improve long term outcomes, including late stent thrombosis. Biodegradable drug-eluting coatings aim to address the long term effects of residual durable polymer after drug elution; the SYNERGY, BioMatrix, and Nobori stents are all promising devices in this category, with minimal polymer through the use of abluminal coatings. Textured stent surfaces have been used to attached drug directly, without polymer; the Yukon Choice and BioFreedom stents have some promising data in this category, while a hydroxyapatite textured surface has had less success. The use of drug-filled reservoirs looked promising initially but the NEVO device has experienced both technical and commercial set-backs. However this approach may eventually make it to market if trials with the Drug-Filled Stent prove to be successful. Non-pharmacological coatings such as silicon carbide, carbon, and titanium-nitride-oxide are also proving to have potential to provide better performance than BMS, without some of the longer term issues associated with DES. In terms of biological coatings, the Genous stent which promotes attachment of endothelial progenitor cells has made good progress while gene-eluting stents still have some practical challenges to overcome. Perhaps the most advancement has been in the field of biodegradable stents. The BVS PLLA device is now seeing increasing clinical use in many complex indications while magnesium stents continue to make steady advancements.

  17. Simulated Bench Testing to Evaluate the Mechanical Performance of New Carotid Stents.

    PubMed

    Kumar, Gideon Praveen; Kabinejadian, Foad; Liu, Jianfei; Ho, Pei; Leo, Hwa Liang; Cui, Fangsen

    2017-03-01

    Our group recently developed a novel covered carotid stent that can prevent emboli while preserving the external carotid artery (ECA) branch blood flow. However, our recent in vitro side-branch ECA flow preservation tests on the covered stents revealed the need for further stent frame design improvements, including the consideration to crimp the stent to a low profile for the delivery of the stent system and having bigger cells. Hence, the current work aims to design new bare metal stents with bigger cell size to improve the crimpability and to accommodate more slits so that the side-branch flow could be further increased. Three new stent designs were analyzed using finite element analysis and benchmarked against two commercially available carotid stents in terms of their mechanical performances such as crimpability, radial strength, and flexibility. Results indicated that the new bare metal stent designs matched well against the commercial stents. Hence our new generation covered stents based on these designs can be expected to perform better in side-branch flow preservation without compromising on their mechanical performances.

  18. Expanded sodalite-type metal-organic frameworks: increased stability and H(2) adsorption through ligand-directed catenation.

    PubMed

    Dinca, Mircea; Dailly, Anne; Tsay, Charlene; Long, Jeffrey R

    2008-01-07

    The torsion between the central benzene ring and the outer aromatic rings in 1,3,5-tri-p-(tetrazol-5-yl)phenylbenzene (H3TPB-3tz) and the absence of such strain in 2,4,6-tri-p-(tetrazol-5-yl)phenyl-s-triazine (H3TPT-3tz) are shown to allow the selective synthesis of noncatenated and catenated versions of expanded sodalite-type metal-organic frameworks. The reaction of H3TPB-3tz with CuCl2.2H2O affords the noncatenated compound Cu3[(Cu4Cl)3(TPB-3tz)8]2.11CuCl2.8H2O.120DMF (2), while the reaction of H3TPT-3tz with MnCl2.4H2O or CuCl2.2H2O generates the catenated compounds Mn3[(Mn4Cl)3(TPT-3tz)8]2.25H2O.15CH3OH.95DMF (3) and Cu3[(Cu4Cl)3(TPT-3tz)8]2.xsolvent (4). Significantly, catenation helps to stabilize the framework toward collapse upon desolvation, leading to an increase in the surface area from 1120 to 1580 m2/g and an increase in the hydrogen storage capacity from 2.8 to 3.7 excess wt % at 77 K for 2 and 3, respectively. The total hydrogen uptake in desolvated 3 reaches 4.5 wt % and 37 g/L at 80 bar and 77 K, demonstrating that control of catenation can be an important factor in the generation of hydrogen storage materials.

  19. Vessel healings after stenting with different polymers in STEMI patients

    PubMed Central

    Jin, Qin-Hua; Chen, Yun-Dai; Tian, Feng; Guo, Jun; Jing, Jing; Sun, Zhi-Jun

    2016-01-01

    Background Different stents implantation in ST-segment elevation myocardial infarction (STEMI) patients may influence the long term prognosis by affecting vessel healings after stenting. The aim of this study was to evaluate the vessel healings after implantation of drug eluting stents (DES) with biodegradable or durable polymer or of bare-metal stents (BMS) in patients with acute STEMI. Methods This study included 50 patients, who underwent follow up angiogram and optical coherence tomography (OCT) assessment about one year after percutaneous coronary intervention (PCI) for STEMI. According to the initial stents types, these patients were classified to durable (n = 19) or biodegradable polymer sirolimus-eluting stents (n = 15), or BMS (n = 16) groups. The conditions of stent struts coverage and malapposition were analyzed with OCT technique. Results A total of 9003 struts were analyzed: 3299, 3202 and 2502 from durable or biodegradable polymer DES, or BMS, respectively. Strut coverage rate (89.0%, 94.9% and 99.3%, respectively), malapposition presence (1.7%, 0.03% and 0 of struts, respectively) and average intimal thickness over struts (76 ± 12 µm, 161 ± 30 µm and 292 ± 29 µm, respectively) were significantly different among different stent groups (all P < 0.001). Conclusions Vessel healing status in STEMI patients is superior after implantation of biodegradable polymer DES than durable polymer DES, while both are inferior to BMS. PMID:27403139

  20. Innovation in aortoiliac stenting: an in vitro comparison

    NASA Astrophysics Data System (ADS)

    Groot Jebbink, E.; Goverde, P. C. J. M.; van Oostayen, J. A.; Reijnen, M. M. P. J.; Slump, C. H.

    2014-03-01

    Aortoiliac occlusive disease (AIOD) may cause disabling claudicatio, due to progression of atherosclerotic plaque. Bypass surgery to treat AIOD has unsurpassed patency results, with 5-year patency rates up to 86%, at the expense of high complication rates (local and systemic morbidity rate of 6% and 16%). Therefore, less invasive, endovascular treatment of AOID with stents in both iliac limbs is the first choice in many cases, however, with limited results (average 5-year patency: 71%, range: 63-82%). Changes in blood flow due to an altered geometry of the bifurcation is likely to be one of the contributing factors. The aim of this study is to compare the geometry and hemodynamics of various aortoiliac stent configurations in vitro. Transparent vessel phantoms mimicking the anatomy of the aortoiliac bifurcation are used to accommodate stent configurations. Bare Metal Kissing stents (BMK), Kissing Covered (KC) stents and the Covered Endovascular Reconstruction of the Aortic Bifurcation (CERAB) configuration are investigated. The models are placed inside a flow rig capable of simulating physiologic relevant flow in the infrarenal area. Dye injection reveals flow disturbances near the neobifurcation of BMK and KC stents as well. At the radial mismatch areas of the KC stents recirculation zones are observed. With the CERAB configuration no flow reversal or large disturbances are observed. In conclusion, dye injection reveals no significant flow disturbances with the new CERAB configuration as seen with the KC and BMK stents.

  1. Stent-induced coronary artery stenosis characterized by multimodal nonlinear optical microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Han-Wei; Simianu, Vlad; Locker, Mattew J.; Cheng, Ji-Xin; Sturek, Michael

    2011-02-01

    We demonstrate for the first time the applicability of multimodal nonlinear optical (NLO) microscopy to the interrogation of stented coronary arteries under different diet and stent deployment conditions. Bare metal stents and Taxus drug-eluting stents (DES) were placed in coronary arteries of Ossabaw pigs of control and atherogenic diet groups. Multimodal NLO imaging was performed to inspect changes in arterial structures and compositions after stenting. Sum frequency generation, one of the multimodalities, was used for the quantitative analysis of collagen content in the peristent and in-stent artery segments of both pig groups. Atherogenic diet increased lipid and collagen in peristent segments. In-stent segments showed decreased collagen expression in neointima compared to media. Deployment of DES in atheromatous arteries inhibited collagen expression in the arterial media.

  2. Endovascular Gene Delivery from a Stent Platform: Gene- Eluting Stents.

    PubMed

    Fishbein, Ilia; Chorny, Michael; Adamo, Richard F; Forbes, Scott P; Corrales, Ricardo A; Alferiev, Ivan S; Levy, Robert J

    A synergistic impact of research in the fields of post-angioplasty restenosis, drug-eluting stents and vascular gene therapy over the past 15 years has shaped the concept of gene-eluting stents. Gene-eluting stents hold promise of overcoming some biological and technical problems inherent to drug-eluting stent technology. As the field of gene-eluting stents matures it becomes evident that all three main design modules of a gene-eluting stent: a therapeutic transgene, a vector and a delivery system are equally important for accomplishing sustained inhibition of neointimal formation in arteries treated with gene delivery stents. This review summarizes prior work on stent-based gene delivery and discusses the main optimization strategies required to move the field of gene-eluting stents to clinical translation.

  3. Endovascular Gene Delivery from a Stent Platform: Gene- Eluting Stents

    PubMed Central

    Fishbein, Ilia; Chorny, Michael; Adamo, Richard F; Forbes, Scott P; Corrales, Ricardo A; Alferiev, Ivan S; Levy, Robert J

    2015-01-01

    A synergistic impact of research in the fields of post-angioplasty restenosis, drug-eluting stents and vascular gene therapy over the past 15 years has shaped the concept of gene-eluting stents. Gene-eluting stents hold promise of overcoming some biological and technical problems inherent to drug-eluting stent technology. As the field of gene-eluting stents matures it becomes evident that all three main design modules of a gene-eluting stent: a therapeutic transgene, a vector and a delivery system are equally important for accomplishing sustained inhibition of neointimal formation in arteries treated with gene delivery stents. This review summarizes prior work on stent-based gene delivery and discusses the main optimization strategies required to move the field of gene-eluting stents to clinical translation. PMID:26225356

  4. Airport and superficial femoral artery obstruction due to a wandering coronary stent: the possibility of airport detection of modern implant metals.

    PubMed

    Teijink, J A W; van Herwaarden, J A; van den Berg, J C; Overtoom, T C; Moll, F L

    2004-06-01

    In the treatment of coronary artery disease, peripheral loss of a coronary stent is an unusual complication. We present the case of a patient who suggested that his right leg claudication was caused by a slipped coronary stent 2 years previously. The patient was convinced about this unusual finding based on an airport security check. Examination proved him to be right. However, the ability to detect an object using eddy currents is dependent on the object's permeability and its conductivity. Ferrous (iron) content is not the critical factor. Modern implant materials and processing techniques result in implants that are difficult to magnetize i.e. their permeability is very low. In addition their conductivity is very low. This enables modern implants to escape detection at airports. For this reason the event at the airport, as described by our patient, is considered coincidental.

  5. [Stent implantation in the treatment of pharynx anastomotic stenosis after cervical esophageal resection: a case report].

    PubMed

    Zang, Chuanshan; Sun, Jian; Sun, Yan

    2016-03-01

    We report the treatment of one patient with pharynx anastomotic stenosis after cervical esophagealresection by stent implantation. The patient suffered from serious pharynx anastomotic stenosis after gastric-pha-ryngeal anastomosis. After balloon-dilatation,a domestic self-expanding Z-stents was implanted in the stricture ofthe esophagus under the X-rays. After stent implantation, the patient has been leading a normal life for threeyears. Balloon dilatation and stent implantation is an effective and safe method in the treatment of patients withpharynx anastomotic stenosis.

  6. Corrosion resistance of polyurethane-coated nitinol cardiovascular stents.

    PubMed

    Mazumder, M M; De, S; Trigwell, S; Ali, N; Mazumder, M K; Mehta, J L

    2003-01-01

    Corrosion of metal stents implanted inside an artery can have two adverse effects: (1) tissue reaction and possible toxic effects from the metal ions leaching out of the stent, and (2) loss of mechanical strength of the stent caused by corrosion. The corrosion resistance of Nitinol (Nickel-Titanium) stents and its modulation with different film thickness of polymer coating was studied against an artificial physiological solution using a Potentiostat/Galvanostat and an electrochemical corrosion cell. The corrosion rate decreased rapidly from 275 microm/year for an uncoated surface down to less than 13 microm/year for a 30 microm thick polyurethane coating. Stainless steel (316L) and Nitinol both contain potentially toxic elements, and both are subject to stress corrosion. Minimization of corrosion can significantly reduce both tissue reaction and structural degradation.

  7. [Safety of magnetic resonance imaging after coronary stenting].

    PubMed

    Sinitsyn, V E; Stukalova, O V; Kupriianova, O M; Ternovoĭ, S K

    2007-01-01

    Magnetic resonance imaging (MRI) is contraindicated to some patients with certain types of metallic devices and implants (e.g. cerebral surgical clips, defibrillators). There are some controversies concerning safety of MRI in patients with metallic coronary stents in cases when MRI examination is performed earlier then one month after stent implantation. Analysis of published data has shown that MRI performed with systems having field strength up to 3 Tesla does not cause migration and heating of both bare and coated stent and is not associated with increased risk of coronary artery thrombosis. MRI can be performed safely in first days after coronary stent implantation. Small local artifacts on MRI images do not influence interpretation of the data (except for cases of coronary magnetic resonance angiography).

  8. Stent Recanalization of Chronic Portal Vein Occlusion in a Child

    SciTech Connect

    Cwikiel, Wojciech; Solvig, Jan; Schroder, Henrik

    2000-07-15

    An 8-year-old boy with a 21/2 year history of portal hypertension and repeated bleedings from esophageal varices, was referred for treatment. The 3.5-cm-long occlusion of the portal vein was passed and the channel created was stabilized with a balloon-expandable stent; a portosystemic stent-shunt was also created. The portosystemic shunt closed spontaneously within 1 month, while the recanalized segment of the portal vein remained open. The pressure gradient between the intrahepatic and extrahepatic portal vein branches dropped from 17 mmHg to 0 mmHg. The pressure in the portal vein dropped from 30 mmHg to 17 mmHg and the bleedings stopped. The next dilation of the stent was performed 12 months later due to an increased pressure gradient; the gastroesophageal varices disappeared completely. Further dilation of the stent was planned after 2, 4, and 6 years.

  9. Functional Nanoarchitectures For Enhanced Drug Eluting Stents.

    PubMed

    Saleh, Yomna E; Gepreel, Mohamed A; Allam, Nageh K

    2017-01-12

    Different strategies have been investigated to allow for optimum duration and conditions for endothelium healing through the enhancement of coronary stents. In this study, a nanoarchitectured system is proposed as a surface modification for drug eluting stents. Highly oriented nanotubes were vertically grown on the surface of a new Ni-free biocompatible Ti-based alloy, as a potential material for self-expandable stents. The fabricated nanotubes were self-grown from the potential stent substrate, which are also proposed to enhance endothelial proliferation while acting as drug reservoir to hinder Vascular Smooth Muscle Cells (VSMC) proliferation. Two morphologies were synthesized to investigate the effect of structure homogeneity on the intended application. The material was characterized by field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Nanoindentation technique was used to study the mechanical properties of the fabricated material. Cytotoxicity and proliferation studies were performed and compared for the two fabricated nanoarchitectures, versus smooth untextured samples, using in-vitro cultured endothelial cells. Finally, the drug loading capacity was experimentally studied and further supported by computational modeling of the release profile.

  10. Functional Nanoarchitectures For Enhanced Drug Eluting Stents

    NASA Astrophysics Data System (ADS)

    Saleh, Yomna E.; Gepreel, Mohamed A.; Allam, Nageh K.

    2017-01-01

    Different strategies have been investigated to allow for optimum duration and conditions for endothelium healing through the enhancement of coronary stents. In this study, a nanoarchitectured system is proposed as a surface modification for drug eluting stents. Highly oriented nanotubes were vertically grown on the surface of a new Ni-free biocompatible Ti-based alloy, as a potential material for self-expandable stents. The fabricated nanotubes were self-grown from the potential stent substrate, which are also proposed to enhance endothelial proliferation while acting as drug reservoir to hinder Vascular Smooth Muscle Cells (VSMC) proliferation. Two morphologies were synthesized to investigate the effect of structure homogeneity on the intended application. The material was characterized by field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Nanoindentation technique was used to study the mechanical properties of the fabricated material. Cytotoxicity and proliferation studies were performed and compared for the two fabricated nanoarchitectures, versus smooth untextured samples, using in-vitro cultured endothelial cells. Finally, the drug loading capacity was experimentally studied and further supported by computational modeling of the release profile.

  11. Functional Nanoarchitectures For Enhanced Drug Eluting Stents

    PubMed Central

    Saleh, Yomna E.; Gepreel, Mohamed A.; Allam, Nageh K.

    2017-01-01

    Different strategies have been investigated to allow for optimum duration and conditions for endothelium healing through the enhancement of coronary stents. In this study, a nanoarchitectured system is proposed as a surface modification for drug eluting stents. Highly oriented nanotubes were vertically grown on the surface of a new Ni-free biocompatible Ti-based alloy, as a potential material for self-expandable stents. The fabricated nanotubes were self-grown from the potential stent substrate, which are also proposed to enhance endothelial proliferation while acting as drug reservoir to hinder Vascular Smooth Muscle Cells (VSMC) proliferation. Two morphologies were synthesized to investigate the effect of structure homogeneity on the intended application. The material was characterized by field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Nanoindentation technique was used to study the mechanical properties of the fabricated material. Cytotoxicity and proliferation studies were performed and compared for the two fabricated nanoarchitectures, versus smooth untextured samples, using in-vitro cultured endothelial cells. Finally, the drug loading capacity was experimentally studied and further supported by computational modeling of the release profile. PMID:28079127

  12. Bioabsorbable Stent Quo Vadis: A Case for Nano-Theranostics

    PubMed Central

    Gundogan, Buket; Tan, Aaron; Farhatnia, Yasmin; Alavijeh, Mohammad S.; Cui, Zhanfeng; Seifalian, Alexander M.

    2014-01-01

    Percutaneous coronary intervention (PCI) is one of the most commonly performed invasive medical procedures in medicine today. Since the first coronary balloon angioplasty in 1977, interventional cardiology has seen a wide array of developments in PCI. Bare metal stents (BMS) were soon superseded by the revolutionary drug-eluting stents (DES), which aimed to address the issue of restenosis found with BMS. However, evidence began to mount against DES, with late-stent thrombosis (ST) rates being higher than that of BMS. The bioabsorbable stent may be a promising alternative, providing vessel patency and support for the necessary time required and thereafter degrade into safe non-toxic compounds which are reabsorbed by the body. This temporary presence provides no triggers for ST, which is brought about by non-endothelialized stent struts and drug polymers remaining in vivo for extended periods of time. Likewise, nano-theranostics incorporated into a bioabsorbable stent of the future may provide an incredibly valuable single platform offering both therapeutic and diagnostic capabilities. Such a stent may allow delivery of therapeutic particles to specific sites thus keeping potential toxicity to a minimum, improved ease of tracking delivery in vivo by embedding imaging agents, controlled rate of therapy release and protection of the implanted therapy. Indeed, nanocarriers may allow an increased therapeutic index as well as offer novel post-stent implantation imaging and diagnostic methods for atherosclerosis, restenosis and thrombosis. It is envisioned that a nano-theranostic stent may well form the cornerstone of future stent designs in clinical practice. PMID:24672583

  13. Endovascular Stenting for Unsuccessful Angioplasty of the Aorta in Aortoarteritis

    SciTech Connect

    Tyagi, Sanjay; Kaul, Upkar A.; Arora, Ramesh

    1999-11-15

    Purpose: The efficacy and safety of endovascular stent implantation to correct dissection or a suboptimal result after percutaneous transluminal angioplasty (PTA) was evaluated in patients suffering from aortic stenosis due to aortoarteritis. Methods: Twelve children and young adults [aged (mean {+-} SD) 18.2 {+-} 8.7 years] underwent stent implantation after PTA of the aorta, seven for obstructive dissection, four for ineffective balloon dilatation, and one for recurrent restenosis. Nine patients underwent implantation of self-expandable stents and three received balloon-expandable Palmaz stents. Results: Stent implantation could be successfully performed in all 12 patients. After stent implantation, the peak systolic pressure gradient decreased from 91 {+-} 33.5 mmHg to 12.4 {+-} 12.5 mmHg (p < 0.001). The diameter of the stenosed segment increased from 4.6 {+-} 0.8 mm to 11.1 {+-} 1.9 mm (p < 0.001). The dissection was completely covered in all seven patients with dissection. Except for epigastric pain with vomiting in one patient, there was no complication. On follow-up, over 12-57 months (mean 26.8 {+-} 10.8 months), 11 patients (91.6%) had marked improvement in their blood pressure. Patients with congestive heart failure and claudication also showed improvement. Repeat catheterization in five patients, between 6-30 months (mean 16.8 {+-} 9.1 months) after stent implantation, showed sustained improvement in four and a fusiform, long segment, intrastent restenosis after 30 months in one child. The stenosis was safely redilated. Conclusion: Endovascular aortic stent implantation is safe and provides good immediate relief in patients with unsatisfactory results after balloon angioplasty. Improvement is sustained in most patients on intermediate-term follow-up.

  14. Biomechanical Challenges to Polymeric Biodegradable Stents.

    PubMed

    Soares, Joao S; Moore, James E

    2016-02-01

    Biodegradable implants have demonstrated clinical success in simple applications (e.g., absorbable sutures) and have shown great potential in many other areas of interventional medicine, such as localized drug delivery, engineered tissue scaffolding, and structural implants. For endovascular stenting and musculoskeletal applications, they can serve as temporary mechanical support that provides a smooth stress-transfer from the degradable implant to the healing tissue. However, for more complex device geometries, in vivo environments, and evolving load-bearing functions, such as required for vascular stents, there are considerable challenges associated with the use of biodegradable materials. A biodegradable stent must restore blood flow and provide support for a predictable appropriate period to facilitate artery healing, and subsequently, fail safely and be absorbed in a controllable manner. Biodegradable polymers are typically weaker than metals currently employed to construct stents, so it is difficult to ensure sufficient strength to keep the artery open and alleviate symptoms acutely while keeping other design parameters within clinically acceptable ranges. These design challenges are serious, given the general lack of understanding of biodegradable polymer behavior and evolution in intimal operating conditions. The modus operandi is mainly empirical and relies heavily on trial-and-error methodologies burdened by difficult, resource-expensive, and time-consuming experiments. We are striving for theoretical advancements systematizing the empirical knowledge into rational frameworks that could be cast into in silico tools for simulation and product development optimization. These challenges are evident when one considers that there are no biodegradable stents on the US market despite more than 30 years of development efforts (and currently only a couple with CE mark). This review summarizes previous efforts at implementing biodegradable stents, discusses the

  15. Transradial approach for vertebral artery stenting

    PubMed Central

    Tekieli, Łukasz; Kabłak-Ziembicka, Anna; Paluszek, Piotr; Trystuła, Mariusz; Wójcik-Pędziwiatr, Magdalena; Machnik, Roman; Pieniążek, Piotr

    2015-01-01

    Introductuion Symptomatic severe vertebral artery (VA) stenosis may be treated safely with stent supported angioplasty via femoral access. There is limited clinical data on transradial approach for VA angioplasty in case of peripheral artery disease. Aim To evaluate the safety and efficacy of transradial angioplasty of symptomatic VA stenosis. Material and methods Fifteen patients (age 66 ±7.4 years, 73% men, with VA > 80% stenosis, 11 right-side, all symptomatic from posterior circulation (history of stroke, TIA, or chronic ischaemia symptoms)) with peripheral artery disease (PAD) or unsuccessful attempt via femoral approach were scheduled for VA angioplasty by radial access. Clinical and duplex ultrasound (DUS) follow-up were performed before discharge and 1, 12, and 24 months after VA angioplasty. Results The technical success rate was 100%. In all cases VA angioplasty was performed with the use of single balloon-mounted stent (9 bare metal stents, 6 drug-eluting stents). The mean NASCET VA stenosis was reduced from 85.3% to 5.3% (p < 0.001). No periprocedural death, stroke, myocardial infarction, or transient ischaemic attack occurred. During 24-months follow-up, in 12 of 15 patients chronic ischaemia symptoms release was observed, and no new acute ischaemic neurological symptoms were diagnosed in all patients. One patient died 20 months after intervention from unknown causes. There was one symptomatic borderline VA in-stent stenosis 12 months after angioplasty. Conclusions Transradial VA stenting may be a very effective and safe procedure, and it may constitute an alternative to the femoral approach in patients with symptomatic VA stenosis. PMID:25848368

  16. An integrated semicompliant balloon ultrasound catheter for quantitative feedback and image guidance during stent deployment.

    PubMed

    Choi, Charles D; Savage, James; Stephens, Douglas N; O'Donnell, Matthew

    2005-09-01

    An integrated balloon ultrasound catheter prototype was designed to image from inside the balloon for real-time guidance during stent deployment. It was fabricated using a semicompliant balloon material (polyethylene) and a 20 MHz, 64-element circumferential ultrasound array. A commercial stent, nominally 4.4 mm in diameter and 12 mm in length, was used for a phantom study and placed along the length of the integrated balloon ultrasound catheter. A rubber phantom was created with an elastic modulus of 175 kPa with a 4.36 mm diameter lumen. Real-time balloon pressure measurements were recorded using a digital pressure sensor, and real-time radio-frequency (RF) data were captured as the balloon was inflated. The slope of the area-pressure ratio (APR) was compared to a reference measure of the balloon and stent expanded in water to determine a measure for optimal stent deployment. The results clearly indicate stent deployment at 11.1 atm using this metric. The APR slope could serve as quantitative feedback parameter for guiding stent deployment to reduce arterial injury and subsequent restenosis. After the stent deployment experiment, RF data were captured as the balloon catheter was moved along the length of the stent in pullback mode to confirm successful stent deployment. Ultimately, an integrated balloon ultrasound catheter could serve as a single catheter intervention device by providing real-time intravascular ultrasound (IVUS) imaging and quantitative feedback during stent deployment.

  17. Assessment of a Polyester-Covered Nitinol Stent in the Canine Aorta and Iliac Arteries

    SciTech Connect

    Castaneda, Flavio; Ball-Kell, Susan M.; Young, Kate; Li Ruizong

    2000-09-15

    Purpose: To evaluate the patency and healing characteristics of a woven polyester fabric-covered stent in the canine model.Methods: Twenty-four self-expanding covered stents were placed in the infrarenal aorta and bilateral common iliac arteries of eight dogs and evaluated at 1 (n = 2), 3 (n = 2), and 6 (n = 4) months. Stent assessment was done using angiography prior to euthanasia, and light and scanning electron microscopy.Results: Angiographically, just prior to euthanasia, 8 of 8 aortic and 14 of 16 iliac endovascular covered stents were patent. Histologically, the stented regions showed complete endothelialization 6 months after graft implantation. A neointima had formed inside the stented vessel regions resulting in complete encasement of the fabric-covered stent by 3 months after graft implantation. Medial compression with smooth muscle cell atrophy was present in all stented regions. Explanted stent wires, examined by scanning electron microscopy, showed pitting but no cracks or breakage.Conclusion: The covered stent demonstrated predictable healing and is effective in preventing stenosis in vessels 10.0 mm or greater in diameter but does not completely preclude stenosis in vessels 6.0 mm or less in diameter.

  18. Renal Artery Stent Outcomes

    PubMed Central

    Murphy, Timothy P.; Cooper, Christopher J.; Matsumoto, Alan H.; Cutlip, Donald E.; Pencina, Karol M.; Jamerson, Kenneth; Tuttle, Katherine R.; Shapiro, Joseph I.; D’Agostino, Ralph; Massaro, Joseph; Henrich, William; Dworkin, Lance D.

    2016-01-01

    BACKGROUND Multiple randomized clinical trials comparing renal artery stent placement plus medical therapy with medical therapy alone have not shown any benefit of stent placement. However, debate continues whether patients with extreme pressure gradients, stenosis severity, or baseline blood pressure benefit from stent revascularization. OBJECTIVES The study sought to test the hypothesis that pressure gradients, stenosis severity, and/or baseline blood pressure affects outcomes after renal artery stent placement. METHODS Using data from 947 patients with a history of hypertension or chronic kidney disease from the largest randomized trial of renal artery stent placement, the CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) study, we performed exploratory analyses to determine if subsets of patients experienced better outcomes after stent placement than the overall cohort. We examined baseline stenosis severity, systolic blood pressure, and translesion pressure gradient (peak systolic and mean) and performed interaction tests and Cox proportional hazards analyses for the occurrence of the primary endpoint through all follow-up, to examine the effect of these variables on outcomes by treatment group. RESULTS There were no statistically significant differences in outcomes based on the examined variables nor were there any consistent nonsignificant trends. CONCLUSIONS Based on data from the CORAL randomized trial, there is no evidence of a significant treatment effect of the renal artery stent procedure compared with medical therapy alone based on stenosis severity, level of systolic blood pressure elevation, or according to the magnitude of the transstenotic pressure gradient. (Benefits of Medical Therapy Plus Stenting for Renal Atherosclerotic Lesions [CORAL]; NCT00081731) PMID:26653621

  19. Promoting endothelial recovery and reducing neointimal hyperplasia using sequential-like release of acetylsalicylic acid and paclitaxel-loaded biodegradable stents

    PubMed Central

    Lee, Cheng-Hung; Yu, Chia-Ying; Chang, Shang-Hung; Hung, Kuo-Chun; Liu, Shih-Jung; Wang, Chao-Jan; Hsu, Ming-Yi; Hsieh, I-Chang; Chen, Wei-Jan; Ko, Yu-Shien; Wen, Ming-Shien

    2014-01-01

    Introduction This work reports on the development of a biodegradable dual-drug-eluting stent with sequential-like and sustainable drug-release of anti-platelet acetylsalicylic acid and anti-smooth muscle cell (SMC) proliferative paclitaxel. Methods To fabricate the biodegradable stents, poly-L-lactide strips are first cut from a solvent-casted film. They are rolled onto the surface of a metal pin to form spiral stents. The stents are then consecutively covered by acetylsalicylic acid and paclitaxel-loaded polylactide-polyglycolide nanofibers via electrospinning. Results Biodegradable stents exhibit mechanical properties that are superior to those of metallic stents. Biodegradable stents sequentially release high concentrations of acetylsalicylic acid and paclitaxel for more than 30 and 60 days, respectively. In vitro, the eluted drugs promote endothelial cell numbers on days 3 and 7, and reduce the proliferation of SMCs in weeks 2, 4, and 8. The stents markedly inhibit the adhesion of platelets on days 3, 7, and 14 relative to a non-drug-eluting stent. In vivo, the implanted stent is intact, and no stent thrombosis is observed in the stent-implanted vessels without the administration of daily oral acetylsalicylic acid. Promotion of endothelial recovery and inhibition of neointimal hyperplasia are also observed on the stented vessels. Conclusion The work demonstrates the efficiency and safety of the biodegradable dual-drug-eluting stents with sequential and sustainable drug release to diseased arteries. PMID:25206303

  20. Radiation and ethylene oxide terminal sterilization experiences with drug eluting stent products.

    PubMed

    Lambert, Byron J; Mendelson, Todd A; Craven, Michael D

    2011-12-01

    Radiation and ethylene oxide terminal sterilization are the two most frequently used processes in the medical device industry to render product within the final sterile barrier package free from viable microorganisms. They are efficacious, safe, and efficient approaches to the manufacture of sterile product. Terminal sterilization is routinely applied to a wide variety of commodity healthcare products (drapes, gowns, etc.) and implantable medical devices (bare metal stents, heart valves, vessel closure devices, etc.) along with products used during implantation procedures (catheters, guidewires, etc.). Terminal sterilization is also routinely used for processing combination products where devices, drugs, and/or biologics are combined on a single product. High patient safety, robust standards, routine process controls, and low-cost manufacturing are appealing aspects of terminal sterilization. As the field of combination products continues to expand and evolve, opportunity exists to expand the application of terminal sterilization to new combination products. Material compatibility challenges must be overcome to realize these opportunities. This article introduces the reader to terminal sterilization concepts, technologies, and the related standards that span different industries (pharmaceutical, medical device, biopharmaceuticals, etc.) and provides guidance on the application of these technologies. Guidance and examples of the application of terminal sterilization are discussed using experiences with drug eluting stents and bioresorbable vascular restoration devices. The examples provide insight into selecting the sterilization method, developing the process around it, and finally qualifying/validating the product in preparation for regulatory approval and commercialization. Future activities, including new sterilization technologies, are briefly discussed.

  1. Percutaneous Palliation of Pancreatic Head Cancer: Randomized Comparison of ePTFE/FEP-Covered Versus Uncovered Nitinol Biliary Stents

    SciTech Connect

    Krokidis, Miltiadis; Fanelli, Fabrizio; Orgera, Gianluigi; Tsetis, Dimitrios; Mouzas, Ioannis; Bezzi, Mario; Kouroumalis, Elias; Pasariello, Roberto; Hatzidakis, Adam

    2011-04-15

    The purpose of this study was to compare the clinical effectiveness of expanded polytetrafluoroethylene/fluorinated-ethylene-propylene (ePTFE/FEP)-covered stents with that of uncovered nitinol stents for the palliation of malignant jaundice caused by inoperable pancreatic head cancer. Eighty patients were enrolled in a prospective randomized study. Bare nitinol stents were used in half of the patients, and ePTFE/FEP-covered stents were used in the remaining patients. Patency, survival, complications, and mean cost were calculated in both groups. Mean patency was 166.0 {+-} 13.11 days for the bare-stent group and 234.0 {+-} 20.87 days for the covered-stent group (p = 0.007). Primary patency rates at 3, 6, and 12 months were 77.5, 69.8, and 69.8% for the bare-stent group and 97.5, 92.2, and 87.6% for the covered-stent group, respectively. Mean secondary patency was 123.7 {+-} 22.5 days for the bare-stent group and 130.3 {+-} 21.4 days for the covered-stent group. Tumour ingrowth occurred exclusively in the bare-stent group in 27.5% of cases (p = 0.002). Median survival was 203.2 {+-} 11.8 days for the bare-stent group and 247.0 {+-} 20 days for the covered-stent group (p = 0.06). Complications and mean cost were similar in both groups. Regarding primary patency and ingrowth rate, ePTFE/FEP-covered stents have shown to be significantly superior to bare nitinol stents for the palliation of malignant jaundice caused by inoperable pancreatic head cancer and pose comparable cost and complications. Use of a covered stent does not significantly influence overall survival rate; nevertheless, the covered endoprosthesis seems to offer result in fewer reinterventions and better quality of patient life.

  2. Direct Adsorption of Anti-CD34 Antibodies on the Nano-Porous Stent Surface to Enhance Endothelialization

    PubMed Central

    Fu, Guowei; Yu, Zhanjiang; Chen, Yongqiang; Chen, Yundai; Tian, Feng; Yang, Xiaoda

    2016-01-01

    Background In-stent restenosis following the insertion of conventional drug-eluting stent has become an extremely serious problem due to coating techniques, with polymer matrices used to bind biological ingredients to the stent surface. However, several studies have indicated that new pro-healing technique could prevent stent thrombosis that can be caused by conventional drug-eluting stents. Methods A novel method of attaching anti-CD34 antibodies directly on the porous surface of a 316L stainless steel bare metal stent was developed in this study, which achieved both high stability of attached anti-CD34 antibodies on the metal stent surface and high antibody activity for stem cell capture. Results The in vitro and in vivo experimental results indicated that the new stent with directly coupled anti-CD34 antibodies can efficiently enhance stent endothelialization. Conclusions This study indicates that we have developed a unique method of attaching anti-CD34 antibodies directly on the porous surface of a 316L stainless steel bare metal stent, which provides a novel polymer-free approach for developing pro-healing stents. PMID:27274167

  3. Shrinking the Supply Chain for Implantable Coronary Stent Devices.

    PubMed

    Moore, Sean S; O'Sullivan, Kevin J; Verdecchia, Francesco

    2016-02-01

    Stenting treatments for the management of disease in the heart, arterial and venous systems, biliary ducts, urethras, ureters, oesophageal tract and prostate have made enormous technical advances since their introduction into clinical use. The progression from metallic to polymer based bio-absorbable stents, coupled with the advances in additive manufacturing techniques, present a unique opportunity to completely re-envision the design, manufacture, and supply chain of stents. This paper looks at current stenting trends and proposes a future where the stent supply chain is condensed from ~150 days to ~20 min. The Cardiologist therefore has the opportunity to become a designer, manufacturer and user with patients receiving custom stents specific to their unique pathology that will be generated, delivered and deployed in the Cath-lab. The paper will outline this potentially revolutionary development and consider the technical challenges that will need to be overcome in order to achieve these ambitious goals. A high level overview of the generating eluting stents in situ program-GENESIS-is outlined including some early experimental work.

  4. Radiotherapy Dose Perturbation of Esophageal Stents Examined in an Experimental Model

    SciTech Connect

    Atwood, Todd F.; Hsu, Annie; Ogara, Maydeen M.; Luba, Daniel G.; Tamler, Bradley J.; DiSario, James A.; Maxim, Peter G.

    2012-04-01

    Purpose: To investigate the radiotherapy dose perturbations caused by esophageal stents in patients undergoing external beam treatments for esophageal cancer. Methods and Materials: Four esophageal stents were examined (three metallic stents: WallFlex, Ultraflex, and Alveolus; one nonmetallic stent with limited radiopaque markers for visualization: Polyflex). All experiments were performed in a liquid water phantom with a custom acrylic stent holder. Radiochromic film was used to measure the dose distributions adjacent to the stents at locations proximal and distal to the radiation source. The stents were placed in an air-filled cavity to simulate the esophagus. Treatment plans were created and delivered for photon energies of 6 and 15 MV, and data analysis was performed on uniform regions of interest, according to the size and geometric placement of the films, to quantify the dose perturbations. Results: The three metallic stents produced the largest dose perturbations with distinct patterns of 'hot' spots (increased dose) measured proximal to the radiation source (up to 15.4%) and both 'cold' (decreased dose) and hot spots measured distal to the radiation source (range, -6.1%-5.8%). The polymeric Polyflex stent produced similar dose perturbations when the radiopaque markers were examined (range, -7.6%-15.4%). However, when the radiopaque markers were excluded from the analysis, the Polyflex stent produced significantly smaller dose perturbations, with maximum hot spots of 7.3% and cold spots of -3.2%. Conclusions: The dose perturbations caused by esophageal stents during the treatment of esophageal cancer using external beam radiotherapy should be understood. These perturbations will result in hot and cold spots in the esophageal mucosa, with varying magnitudes depending on the stent. The nonmetallic Polyflex stent appears to be the most suitable for patients undergoing radiotherapy, but further studies are necessary to determine the clinical significance of the

  5. Behaviour of implantable coronary stents during magnetic resonance imaging.

    PubMed

    Friedrich, Matthias G; Strohm, Oliver; Kivelitz, Dietmar; Gross, Werner; Wagner, Anja; Schulz-Menger, Jeanette; Liu, Xiaomeng; Hamm, Bernd

    1999-01-01

    BACKGROUND: Magnetic resonance imaging (MRI) becomes more and more a routine diagnostic tool in clinical cardiology. In patients undergoing MRI, metallic implants may be harmful by motion or heating under certain circumstances. Many cardiac patients have implanted intracoronary stents. However, the safety of these metallic implants and especially their temperature behaviour during MRI has not been sufficiently tested. METHODS: This study investigated motion and temperature changes of 14 different stents for intracoronary application in two clinical scanners at field strengths of 1.0 and 1.5 T. At 1.5 T these studies were repeated after implantation of the stents into the coronary arteries of excised porcine hearts. Furthermore, the clinical status of 33 patients was assessed after a cardiac MR study and compared with a group of 33 patients matched for age, sex and risk factors for restenosis. RESULTS: No visible motion of the stents was observed. Furthermore, using a highly sensitive infrared camera any significant heating of the stents during MRI could be excluded. The rate of clinical events was not different in patients after MRI as compared with the control group. CONCLUSION: It is concluded that MRI is safe in patients with the currently available intracoronary stents.

  6. Heating of cardiovascular stents in intense radiofrequency magnetic fields.

    PubMed

    Foster, K R; Goldberg, R; Bonsignore, C

    1999-01-01

    We consider the heating of a metal stent in an alternating magnetic field from an induction heating furnace. An approximate theoretical analysis is conducted to estimate the magnetic field strength needed to produce substantial temperature increases. Experiments of stent heating in industrial furnaces are reported, which confirm the model. The results show that magnetic fields inside inductance furnaces are capable of significantly heating stents. However, the fields fall off very quickly with distance and in most locations outside the heating coil, field levels are far too small to produce significant heating. The ANSI/IEEE C95.1-1992 limits for human exposure to alternating magnetic fields provide adequate protection against potential excessive heating of the stents.

  7. Postcatheterization Femoral Arteriovenous Fistulas: Endovascular Treatment with Stent-Grafts

    SciTech Connect

    Onal, Baran Kosar, Sule; Gumus, Terman; Ilgit, Erhan T.; Akpek, Sergin

    2004-09-15

    Purpose: To report our results of stent-graft implantation for the endovascular treatment of postcatheterization femoral arteriovenous fistulas (AVFs) occurring between the deep femoral artery and the femoral vein.Methods: Endovascular treatment of iatrogenic femoral AVFs as a result of arterial puncture for coronary angiography and/or angioplasty was attempted in 10 cases. Balloon-expandable stent-grafts, one for each lesion, were used to repair the fistulas, which were between the deep femoral artery and the femoral vein in all cases. Stent-graft implantation to the deep femoral artery was performed by a contralateral retrograde approach.Results: All stent-grafts were deployed successfully. Complete closure of the fistulas was accomplished immediately in nine of 10 cases. In one case, complete closure could not be obtained but the fact that the complaint subsided was taken to indicate clinical success. In three cases, side branch occlusion of the deep femoral artery occurred. No complications were observed after implantation. Follow-up for 8-31 months (mean 18.5 months) with color Doppler ultrasonography revealed patency of the stented arterial segments without recurrent arteriovenous shunting in those nine patients who had successful immediate closure of their AVFs.Conclusion: Our results with a mean follow-up 18.5 months suggest that stent-graft implantation for the closure of postcatheterization femoral AVFs originating from the deep femoral artery is an effective, minimally invasive alternative procedure.

  8. [Mechanical analysis on a new type of biodegradable magnesium-alloy stent].

    PubMed

    Wang, Xiaoping; Cui, Fuzhai; Li, Jianguo; Zhao, Xingshan

    2009-04-01

    Biodegradable magnesium-alloy stents have been employed in animal experiments and clinical researches in recent years. Magnesium-alloy stents have been reported to be biocompatible, and degradable due to corrosion after being implanted into blood vessel. However, magnesium alloy is brittle compared with stainless steel. This may cause strut break under large deformation. In this paper, a finite element model of magnesium-alloy stent was set up, with reference to pictures from Biotronik Corporation, to simulate the expanding and bending processes. The results of analysis show that the maximum strain during expanding reaches 20%, being greater than the elongation limit of the commercially available magnesium alloys. Therefore, to avoid strut breakage during expanding, the magnesium alloys should be custom-made. The plasticity of the material should be improved by grain refinement processes before practicable magnesium-alloy stents could be developed.

  9. Impact of a Newly Developed Short Double-Balloon Enteroscope on Stent Placement in Patients with Surgically Altered Anatomies

    PubMed Central

    Tsutsumi, Koichiro; Kato, Hironari; Okada, Hiroyuki

    2017-01-01

    A newly developed short double-balloon enteroscope with a working channel enlarged to a diameter of 3.2 mm is a novel innovation in stent placement for patients with surgically altered anatomies. Herein, we report three patients in whom this new scope contributed to an efficient technique and ideal treatment. In the first case, the double guidewire technique was efficient and effective for multiple stent placements. In the second case, covered self-expandable metal stent (SEMS) placement, which is the standard treatment for malignant biliary obstruction, could be performed in a technologically sound and safe manner. In the third case, SEMS placement was performed as palliative treatment for malignant afferent-loop obstruction; this procedure could be performed soundly and safely using the through-the-scope technique. The wider working channel of this new scope also facilitates a smoother accessory insertion and high suction performance, which reduces procedure time and stress on endoscopists. Furthermore, this new scope, which has advanced force transmission, adaptive bending, and a smaller turning radius, is expected to be highly successful in both diagnosis and therapy for various digestive diseases in patients with surgically altered anatomies. PMID:28208009

  10. Late Recurrence of a Hepatic Artery Aneurysm After Treatment Using an Endovascular Stent

    SciTech Connect

    Downer, Jonathan; Choji, Kiyoshi

    2008-11-15

    Endovascular stent placement and coil embolization have become established options in the treatment of visceral arterial aneurysms. In this article we report the case of an 83-year-old presenting with gastrointestinal hemorrhage due to a recurrent hepatic arterial aneurysm occurring 12 years after treatment with an endovascular stent. The recurrent aneurysm had resulted from stent fracture and was successfully treated by coil embolization. To our knowledge, stent fracture complicating the endovascular treatment of a visceral artery aneurysm has not been described in the published literature. With the increasing use of metallic endoprostheses in interventional radiology, recognizing and reporting device failure are of critical importance.

  11. Covered Biodegradable Stent: New Therapeutic Option for the Management of Esophageal Perforation or Anastomotic Leak

    SciTech Connect

    Cerna, Marie; Koecher, Martin Valek, Vlastimil; Aujesky, Rene; Neoral, Cestmir; Andrasina, Tomas; Panek, Jiri; Mahathmakanthi, Shankari

    2011-12-15

    Purpose: This study was designed to evaluate our experience with the treatment of postoperative anastomotic leaks and benign esophageal perforations with covered biodegradable stents. Materials and Methods: From 2008 to 2010, we treated five men with either an anastomotic leak or benign esophageal perforation by implanting of covered biodegradable Ella-BD stents. The average age of the patients was 60 (range, 38-74) years. Postoperative anastomotic leaks were treated in four patients (1 after esophagectomy, 1 after resection of diverticulum, 2 after gastrectomy). In one patient, perforation occurred as a complication of the treatment of an esophageal rupture (which occurred during a balloon dilatation of benign stenosis) with a metallic stent. Results: Seven covered biodegradable stents were implanted in five patients. Primary technical success was 100%. Clinical success (leak sealing) was achieved in four of the five patients (80%). Stent migration occurred in three patients. In two of these patients, the leak had been sealed by the time of stent migration, therefore no reintervention was necessary. In one patient an additional stent had to be implanted. Conclusion: The use of biodegradable covered stents for the treatment of anastomotic leaks or esophageal perforations is technically feasible and safe. The initial results are promising; however, larger number of patients will be required to evaluate the capability of these biodegradable stents in the future. The use of biodegradable material for coverage of the stent is essential.

  12. Dramatic effects of chlorine addition on expanding synthesis conditions for fluorine-free metal-organic decomposition YBa2Cu3O y films

    NASA Astrophysics Data System (ADS)

    Motoki, Takanori; Ikeda, Shuhei; Honda, Genki; Nagaishi, Tatsuoki; Nakamura, Shin-ichi; Shimoyama, Jun-ichi

    2017-02-01

    The synthesis conditions of fluorine-free metal-organic decomposition (FF-MOD)-processed YBa2Cu3O y (YBCO) films on buffered metallic substrates have been systematically investigated. Chlorine addition to the starting solution was found to be quite effective for expanding the synthesis conditions of highly c-axis-oriented YBCO films. YBCO films showing a high critical current, ˜100 A/cm (77 K, ˜0 T), were successfully obtained by sintering at 740 °C, which is ˜50 °C lower than the typical sintering temperature for FF-MOD-processed YBCO films. This strongly indicated that chlorine addition is promising for the development of long and homogeneous YBCO tapes even by sintering at a low temperature of ˜740 °C.

  13. [Stent, endovascular prosthesis, net or strut? What would British dentist Charles Stent (1807-1885) have to say on all this?].

    PubMed

    Lukenda, Josip; Biocina-Lukenda, Dolores

    2009-01-01

    The word stent appears in the Index Medicus as of 1952, while in Croatian articles as of 1993. The origin of the word has been attributed to British dentist Charles. T. Stent (1807-1885), maker of the compound for dental impressions (Stent's compound). Viennese surgeon, Johannes F. S. Esser (1877-1946) used the compound in plastic surgery of the face calling it an eponym Stent's mould. During the 1950's, William H. ReMine and John H. Grindlay used Stent's principle for omentum lined plastic tubes in the bile duct of a dog. The development of today's vascular stents began in 1912 when French Nobel Prize winner Alexis Carrel (1873-1944) implanted glass tubes in the arteries of dogs. The first metal spirals were implanted in the arteries of dogs by Charles T. Dotter (1920-1985), while the first stents in human arteries were implanted by French doctors Ulrich Sigwart and Jacques Puel in Toulouse in 1986. Some authors claim that the origin of the word stent is associated with the Scotish word stynt or stent, meaning stretched out river fishing nets.

  14. ISR II study: a long-term evaluation of sirolimus-eluting stent in the treatment of patients with in-stent restenotic native coronary artery lesions.

    PubMed

    Commeau, Philippe; Barragan, Paul T; Roquebert, Pierre O; Siméoni, Jean B

    2005-10-01

    The aim of this pilot study was to determine the safety and long-term efficacy of treating intrastent restenosis (ISR) with the slow-release sirolimus-eluting stent Bx Velocity (Cypher stent) without intravascular ultrasound (IVUS) guidance. Of patients who received a bare metal stent implantation and presented an ISR, 30-80% of the patients will develop a second restenosis within the stent, at the stent edges or both. To date, intravascular brachytherapy using beta- and gamma-radiation has been the only effective treatment for ISR. Twenty-three patients with ISR and evidence of ischemia were treated with Cypher stent. Clinical information was collected 1, 8, 12, and 24 months after stent implantation. During the first 8 months of the study, in-stent lumen diameter remained essentially unchanged from postprocedure in 80% of the case. The target lesion repeat revascularization (TLR) was 17%, of which 50% were oculostenotic reflexes. Only one patient presented a restenosis greater than 70%. During the 2-year study period, the TLR rate was 17%; the major adverse coronary event rate was 26%, and the non-Q-wave myocardial infarction (MI) rate was 9%. There were no reports of death, coronary artery bypass grafting, or Q-wave MI during the study. This study demonstrates the feasibility of using sirolimus-eluting stents without IVUS guidance for the treatment of ISR, providing long-term stability of immediate results.

  15. Point-of-care seeding of nitinol stents with blood-derived endothelial cells.

    PubMed

    Jantzen, Alexandra E; Noviani, Maria; Mills, James S; Baker, Katherine M; Lin, Fu-Hsiung; Truskey, George A; Achneck, Hardean E

    2016-11-01

    Nitinol-based vascular devices, for example, peripheral and intracranial stents, are limited by thrombosis and restenosis. To ameliorate these complications, we developed a technology to promote vessel healing by rapidly seeding (QuickSeeding) autologous blood-derived endothelial cells (ECs) onto modified self-expanding nitinol stent delivery systems immediately before implantation. Several thousand micropores were laser-drilled into a delivery system sheath surrounding a commercial nitinol stent to allow for exit of an infused cell suspension. As suspension medium flowed outward through the micropores, ECs flowed through the delivery system attaching to the stent surface. The QuickSeeded ECs adhered to and spread on the stent surface following 24-h in vitro culture under static or flow conditions. Further, QuickSeeded ECs on stents that were deployed into porcine carotid arteries spread to endothelialize stent struts within 48 h (n = 4). The QuickSeeded stent struts produced significantly more nitric oxide in ex vivo flow circuits after 24 h, as compared to static conditions (n = 5). In conclusion, ECs QuickSeeded onto commercial nitinol stents within minutes of implantation spread to form a functional layer in vitro and in vivo, providing proof of concept that the novel QuickSeeding method with modified delivery systems can be used to seed functional autologous endothelium at the point of care. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1658-1665, 2016.

  16. A numerical study on the application of the functionally graded materials in the stent design.

    PubMed

    Khosravi, Arezoo; Bahreinizad, Hossein; Bani, Milad Salimi; Karimi, Alireza

    2017-04-01

    Undesirable deformation of the stent can induce a significant amount of injure not only to the blood vessel but also to the plaque. The objective of this study was to reduce/minimize these undesirable deformations by the application of Functionally Graded Materials (FGM). To do this, Finite Element (FE) method was employed to simulate the expansion of a stent and the corresponding displacement of the stenosis plaque. Three hyperelastic plaque types as well as five elastoplastic stents were simulated. Dogboning, foreshortening, maximum stress in the plaque, and the pressure which is needed to fully expand the stent for different stent materials, were acquired. While all FGMs had lower dogboning in comparison to the stents made of the uniform materials, the stent with the lowest heterogeneous index displayed the lowest amount of dogboning. Steel stent showed the lowest foreshortening and fully expansion pressure but the difference was much lower than that the one for dogboning. Therefore, the FGM with the heterogeneous index of 0.5 is expected to exhibit the most suitable results. In addition, the results revealed that the material parameters has crucial effects on the deformation of the stent and, as a result, as a design point of view the FGM parameters can be tailored to achieve the goal of the biomechanical optimization.

  17. [Stents in iliac vascular changes].

    PubMed

    Gross-Fengels, W; Friedmann, G; Fischbach, R; Erasmi, H; Bulling, B

    1991-01-01

    The results of 79 iliac stent placements in 64 patients are reported. The technical success rate was 96%. The systolic pressure gradient dropped from 44 mmHg before to 2.8 mmHg after stent placement. This differed significantly as compared to a group treated by conventional PTA (gradient 5.8 mmHg). The cumulative patency after 18-20 months was 90%. Angiographic controls up to 19 months after "stenting" demonstrated only one secondary stent occlusion. Iliac stents therefore are a very valuable supplement to classic PTA.

  18. Customized covered stent graft for percutaneous closure of Fontan baffle leak.

    PubMed

    Binder, Ronald K; Nietlispach, Fabian; Carere, Ronald G

    2013-05-01

    We report the innovation of both a partly-covered and completely-covered, variable-diameter, balloon-expandable stent that was custom-designed by NuMed, Inc for percutaneous closure of a baffle leak after total caval pulmonary connection (TCPC). A 50-year-old patient, born with tricuspid atresia, who had undergone TCPC, developed severe persistent cyanosis due to a right-to-left shunt through a TCPC baffle leak. Re-operation was deemed too high risk. Therefore, considering his complex anatomy, a custom-made, partly-covered, tapered, balloon-expandable stent was designed and successfully deployed. Months later, the shunt recurred at the junction of the covered to uncovered stent cells; subsequently, a second fully-covered, custom-made, tapered stent was implanted with an excellent outcome. The use of covered or partly-covered customized variable-diameter stents for closure of baffle leak after TCPC is feasible and resulted in marked clinical improvement. Customized balloon-expandable stents may be superior to traditional cylindrical stents because of better anchoring and apposition.

  19. Long-term effects of forgotten biliary stents: a case series and literature review.

    PubMed

    Odabasi, Mehmet; Arslan, Cem; Akbulut, Sami; Abuoglu, Haci Hasan; Ozkan, Erkan; Yildiz, Mehmet Kamil; Eris, Cengiz; Gunay, Emre; Tekesin, Kemal; Muftuoglu, Tolga

    2014-01-01

    There are many studies about the biliary stents, however there is a little information about the long-term stayed forgotten biliary stents except a few case reports. We have reported the results of a number of cases with biliary stents that were forgotten or omitted by the patient and the endoscopist. During February 2010 to May 2013, five patients were referred to the general surgery clinic of Haydarpasa Numune Training and Research Hospital, Istanbul Turkey. Past history and medical documents submitted by the patient did not indicate a replacement of the biliary stent in 3 patients. Two patients knew that they had biliary stents. We also conducted a literature review via the PubMed and Google Scholar databases of English language studies published until March 2014 on forgotten biliary stent. There were 3 men and 2 women ranging in age from 22 to 68 years (mean age 41.6 years). Patients presented with pain in the upper abdomen, jaundice, fever, abnormal liver function tests or dilatation of the biliary tract alone or in combination. Patients' demographic findings are presented in Table 1. A review of three cases reported in the English medical literature also discussed. The mean duration of the patency of the stent is about 12 months. The biliary stenting is performed either with plastic or metal stents, studies recommending their replacement after 3-6 months. Patients with long stayed forgotten biliary stents are inevitably treated with surgical intervention. We recommend for all endoscopic retrograde cholangiopancreatography units provide a stent registry system that the stents placed for various therapeutic procedures are not forgotten both by the patient as well as the physician. There should be a deadline for biliary stents in the registry system for each patient.

  20. Carotid stenting using tapered and nontapered stents: associated neurological complications and restenosis rates.

    PubMed

    Brown, Katherine E; Usman, Asad; Kibbe, Melina R; Morasch, Mark D; Matsumura, Jon S; Pearce, William H; Amaranto, Daniel J; Eskandari, Mark K

    2009-01-01

    Self-expanding stent design systems for carotid artery stenting (CAS) have morphed from nontapered (NTS) to tapered (TS); however, the impact of this change is unknown. We reviewed the outcomes of CAS with these two broad categories of stents in a single-center retrospective review of 308 CAS procedures from May 2001 to July 2007. Nitinol self-expanding TS or NTS coupled with cerebral embolic protection devices were used to treat extracranial carotid occlusive disease. Data analysis included demographics, procedural records, duplex exams, and conventional arteriography. Mean follow-up was 18 months (range 1-69). Restenosis was defined as >or=80% in-stent carotid artery stenosis by angiography. The mean age of the entire cohort was 71.3 years (75% men, 25% women). Of the 308 cases, 233 were de novo lesions and 75 had a prior ipsilateral carotid endarterectomy (n = 44) or external beam radiation exposure (n = 31). Preprocedure neurological symptoms were present in 30% of patients. TS were used in 156 procedures and NTS in 152 procedures. The 30-day ipsilateral stroke and death rates were 1.3% and 0.3%, respectively. An additional three (1.0%) posterior circulation strokes occurred. There was no statistically significant difference in the 30-day total stroke rates between TS (3.2%, n = 5) and NTS (1.3%, n = 2) (p = 0.5). At midterm follow-up, restenosis or asymptomatic occlusion was detected in eight cases (2.6%). All occurred in arteries treated with NTS, and this was statistically different when compared to arteries treated with TS (p = 0.03). Furthermore, a post-hoc subgroup analysis revealed significant correlation (chi(2) = 0.02) for restenosis in "hostile necks" when separated by TS vs. NTS. Early CAS outcomes between TS and NTS are comparable. In contrast, self-expanding nitinol TS may have a lower incidence of significant restenosis or asymptomatic occlusion when compared to NTS.

  1. Antiplatelet therapy in patients undergoing coronary stenting

    PubMed Central

    ten Berg, J.M.; van Werkum, J.W.; Heestermans, A.A.C.M.; Jaarsma, W.; Hautvast, R.M.A.; den Heijer, P.; de Boer, M.J.

    2006-01-01

    Background Anticoagulation after coronary stenting is essential to prevent stent thrombosis. Drug-eluting stents, which are the preferred therapy, may be associated with a higher tendency for stent thrombosis. Methods Patients who underwent coronary stent placement and presented with late stent thrombosis are described. Results Eight patients with stent thrombosis are presented. Early discontinuation of the antithrombotic medication is associated with the occurrence of these complications. Conclusion Long-term antithrombotic therapy seems essential to prevent stent thrombosis, especially for patients treated with drug-eluting stents. PMID:25696663

  2. Collagen Matrix Remodeling in Stented Pulmonary Arteries after Transapical Heart Valve Replacement.

    PubMed

    Ghazanfari, Samaneh; Driessen-Mol, Anita; Hoerstrup, Simon P; Baaijens, Frank P T; Bouten, Carlijn V C

    2016-01-01

    The use of valved stents for minimally invasive replacement of semilunar heart valves is expected to change the extracellular matrix and mechanical function of the native artery and may thus impair long-term functionality of the implant. Here we investigate the impact of the stent on matrix remodeling of the pulmonary artery in a sheep model, focusing on matrix composition and collagen (re)orientation of the host tissue. Ovine native pulmonary arteries were harvested 8 (n = 2), 16 (n = 4) and 24 (n = 2) weeks after transapical implantation of self-expandable stented heart valves. Second harmonic generation (SHG) microscopy was used to assess the collagen (re)orientation of fresh tissue samples. The collagen and elastin content was quantified using biochemical assays. SHG microscopy revealed regional differences in collagen organization in all explants. In the adventitial layer of the arterial wall far distal to the stent (considered as the control tissue), we observed wavy collagen fibers oriented in the circumferential direction. These circumferential fibers were more straightened in the adventitial layer located behind the stent. On the luminal side of the wall behind the stent, collagen fibers were aligned along the stent struts and randomly oriented between the struts. Immediately distal to the stent, however, fibers on both the luminal and the adventitial side of the wall were oriented in the axial direction, demonstrating the stent impact on the collagen structure of surrounding arterial tissues. Collagen orientation patterns did not change with implantation time, and biochemical analyses showed no changes in the trend of collagen and elastin content with implantation time or location of the vascular wall. We hypothesize that the collagen fibers on the adventitial side of the arterial wall and behind the stent straighten in response to the arterial stretch caused by oversizing of the stent. However, the collagen organization on the luminal side suggests that

  3. Experimental Study of Poly-l-Lactic Acid Biodegradable Stents in Normal Canine Bile Ducts

    SciTech Connect

    Yamamoto, Kiyosei Yoshioka, Tetsuya; Furuichi, Kinya; Sakaguchi, Hiroshi; Anai, Hiroshi; Tanaka, Toshihiro; Morimoto, Kengo; Uchida, Hideo; Kichikawa, Kimihiko

    2011-06-15

    Purpose: This study was designed to clarify the advantages of biodegradable stents in terms of mucosal reaction and biodegradation after placement. We designed a biodegradable stent and assessed stent degradation and changes in the normal bile ducts of dogs. Methods: The biodegradable stent is a balloon-expandable Z stent consisting of poly-l-lactic acid (PLLA) with a diameter of 6 mm and a length of 15 mm. We assessed four groups of three beagle dogs each at 1, 3, 6, and 9 months of follow-up. After evaluating stent migration by radiography and stent and bile duct patency by cholangiography, the dogs were sacrificed to remove the bile duct together with the stent. The bile duct lumen was examined macroscopically and histologically, and the stent degradation was examined macroscopically and by scanning electron microscopy (SEM). Results: Bile duct obstruction was absent and none of the stents migrated. Macroscopic evaluation showed moderate endothelial proliferation in the bile ducts at the implant sites at 3 and 6 months and a slight change at 9 months. Slight mononuclear cell infiltration was histologically identified at all time points and epithelial hyperplasia that was moderate at 3 months was reduced to slight at 6 and 9 months. Stent degradation was macroscopically evident in all animals at 9 months and was proven by SEM in two dogs at 6 months and in all of them at 9 months. Conclusions: Our results suggest that PLLA bioabsorbable stents seems to be useful for implantation in the biliary system with further investigation.

  4. Collagen Matrix Remodeling in Stented Pulmonary Arteries after Transapical Heart Valve Replacement

    PubMed Central

    Ghazanfari, Samaneh; Driessen-Mol, Anita; Hoerstrup, Simon P.; Baaijens, Frank P.T.; Bouten, Carlijn V.C.

    2016-01-01

    The use of valved stents for minimally invasive replacement of semilunar heart valves is expected to change the extracellular matrix and mechanical function of the native artery and may thus impair long-term functionality of the implant. Here we investigate the impact of the stent on matrix remodeling of the pulmonary artery in a sheep model, focusing on matrix composition and collagen (re)orientation of the host tissue. Ovine native pulmonary arteries were harvested 8 (n = 2), 16 (n = 4) and 24 (n = 2) weeks after transapical implantation of self-expandable stented heart valves. Second harmonic generation (SHG) microscopy was used to assess the collagen (re)orientation of fresh tissue samples. The collagen and elastin content was quantified using biochemical assays. SHG microscopy revealed regional differences in collagen organization in all explants. In the adventitial layer of the arterial wall far distal to the stent (considered as the control tissue), we observed wavy collagen fibers oriented in the circumferential direction. These circumferential fibers were more straightened in the adventitial layer located behind the stent. On the luminal side of the wall behind the stent, collagen fibers were aligned along the stent struts and randomly oriented between the struts. Immediately distal to the stent, however, fibers on both the luminal and the adventitial side of the wall were oriented in the axial direction, demonstrating the stent impact on the collagen structure of surrounding arterial tissues. Collagen orientation patterns did not change with implantation time, and biochemical analyses showed no changes in the trend of collagen and elastin content with implantation time or location of the vascular wall. We hypothesize that the collagen fibers on the adventitial side of the arterial wall and behind the stent straighten in response to the arterial stretch caused by oversizing of the stent. However, the collagen organization on the luminal side suggests that

  5. Overlap stenting for in-stent restenosis after carotid artery stenting

    PubMed Central

    Nishihori, Masahiro; Ohshima, Tomotaka; Yamamoto, Taiki; Goto, Shunsaku; Nishizawa, Toshihisa; Shimato, Shinji; Izumi, Takashi; Kato, Kyozo

    2016-01-01

    ABSTRACT Our aim was to assess the clinical safety and efficacy of overlap stenting for in-stent restenosis after carotid artery stenting. The study was conducted between July 2008 and February 2015. A database of consecutive carotid artery stenting procedures was retrospectively assessed to identify the cases of in-stent restenosis that were treated with overlap stenting under proximal or distal protection. The clinical and radiological records of the patients were then reviewed. Of the 155 CAS procedures in 149 patients from the database, 6 patients met the inclusion criteria. All the 6 patients were initially treated with moderate dilatation because of the presence of an unstable plaque. The technical success rate of the overlap stenting was 100%, with no 30-day mortality or morbidity. In addition, there was no further in-stent restenosis during a follow-up period of over 12 months. These results indicated that overlap stenting for in-stent restenosis after carotid artery stenting was both safe and effective in our cohort. PMID:27303101

  6. Coronary artery bypass is superior to drug-eluting stents in multivessel coronary artery disease.

    PubMed

    Guyton, Robert A

    2006-06-01

    Percutaneous intervention for the treatment of multivessel coronary artery disease continues to displace coronary artery bypass graft surgery. But controlled trials of percutaneous intervention versus coronary bypass, in meta-analysis, have shown a significant survival advantage for coronary bypass. Studies of bare metal stents have not presented any data to prompt reversal of this conclusion for all but the small portion of patients most suited for stenting. Drug-eluting stents have no survival advantage compared with bare metal stents. Data from real-world registries have shown that the current therapy of multivessel disease patients has resulted in a relative excess mortality of as much as 46% in patients with initial stenting compared with patients with initial coronary bypass. Ethical considerations demand that patients with multivessel disease be informed of the documented mortality benefit of coronary bypass graft surgery.

  7. Coronary covered stents.

    PubMed

    Kilic, Ismail Dogu; Fabris, Enrico; Serdoz, Roberta; Caiazzo, Gianluca; Foin, Nicolas; Abou-Sherif, Sara; Di Mario, Carlo

    2016-11-20

    Covered stents offer an effective bail-out strategy in vessel perforations, are an alternative to surgery for the exclusion of coronary aneurysms, and have a potential role in the treatment of friable embolisation-prone plaques. The aim of this manuscript is to offer an overview of currently available platforms and to report results obtained in prior studies.

  8. Endovascular Management of Chronic Type B Dissecting Aortic Aneurysm Utilizing Aortic and Renal Stents

    SciTech Connect

    Taylor, J. D. Dunckley, M.; Thompson, M.; Morgan, R. A.

    2008-07-15

    Over the last 10 years endovascular stent-graft placement has been increasingly used to treat complicated acute Type B thoracic aortic dissections. While studies have demonstrated the use of additional aortic stent-grafts to treat continued false lumen perfusion and case reports have detailed the use of renal artery stents to treat renal ischemia related to aortic dissection, to our knowledge the adjuvant use of renal artery stents to reduce false lumen perfusion has not been reported. We present the case of a 72-year-old male who had previously undergone endovascular repair of a complicated Type B thoracic aortic dissection and presented with an expanding false lumen in the peridiaphragmatic aorta despite coverage of the entire thoracic aorta. This was treated by closure of a right renal fenestration using a renal stent.

  9. Rotational Atherectomy and Stent Implantation for Calcified Left Main Lesions

    PubMed Central

    Schwartz, Bryan G.; Mayeda, Guy S.; Economides, Christina; Kloner, Robert A.; Shavelle, David M.; Burstein, Steven

    2011-01-01

    Background Left main coronary artery (LMCA) bifurcation and heavily calcified lesions are common and challenging to treat percutaneously. Rotational atherectomy (RA) may be beneficial in this setting to facilitate stent placement though direct supporting evidence is lacking. This study sought to analyze patients who underwent RA of the LMCA. Methods Consecutive cases involving RA of the LMCA between 1/1/2004 and 12/31/2009 at a private, tertiary referral hospital were reviewed retrospectively. Medical records, angiograms and clinically driven follow-up were reviewed. Results Thirty-one cases were identified (20 protected, 11 unprotected), including 23 with stent implantation (21 drug-eluting, 2 bare metal). All 31 lesions had moderate to severe calcification, 84% involved the distal segment. Mean burr-to-vessel ratio was 0.43. Overall angiographic success was 90% (28/31) and was higher with a drug-eluting stent versus no stent (100% vs. 62%; P = 0.0153). In-hospital major adverse cardiovascular events (MACE) occurred in 1 patient (3%). Mid-term MACE occurred in 6 patients (26%) and tended to occur less frequently in patients with protected LMCAs (P = 0.0697). At final follow-up, patients were more likely to be alive and free from angina with a protected LMCA (94% vs. 57% unprotected; P = 0.0564) and with a drug-eluting stent (89% vs. 50% with no stent; P = 0.0281). Conclusions RA of the LMCA to facilitate stent implantation appears to be safe and effective with favorable mid-term outcomes. In the setting of severe calcification and distal LMCA involvement RA and drug-eluting stent implantation should be considered.

  10. Colonic stent placement as a bridge to surgery in patients with left-sided malignant large bowel obstruction. An observational study

    PubMed Central

    OCCHIONORELLI, S.; TARTARINI, D.; CAPPELLARI, L.; STANO, R.; VASQUEZ, G.

    2014-01-01

    Background Acute left-sided malignant colonic obstruction is common in elderly patients, in which emergency surgery is related with high morbidity and mortality rates, and often necessitates a two-step resection. Although the use of self-expanding metallic stents (SEMS) in elderly patients has not been adequately described yet, there are almost two international important trials which are still in progress, the stenting technique is established to be, by the international literature, an useful treatment with low morbidity and mortality. It’s also a bridge to surgery, since the insertion of a SEMS can decompress the obstruction, making bowel and patient preparation possible and facilitating single-stage surgical resection. Palliative stenting can improve quality of life when compared to surgery in patients with metastasis or high co-morbidity. The aim of this study is to analyze mortality, avoidance of stoma, short- and long-term survival in patient with malignant left-sided large bowel obstruction who underwent to stent placement in our Emergency Surgery Unit, which is operative since November 2010 in our city Hospital in Ferrara. Patients and methods Between November 2010 and December 2012 a total of 15 patients with acute left-sided malignant large bowel obstruction suitable for colonic stent application were admitted to Emergency Surgery Unit. Among these patients, 9 underwent to self-expanding metallic stent placement (group A), the other (group B) 6 patient underwent to emergency surgery. In this observational not-randomized study we analyzed the efficacy and safety of SEMS placement for patients either as a bridge to surgery or as a palliation, beside the short term and long term outcomes, versus those patients operated straight. Results Self-expanding metallic stents were successfully implanted in 9 of the 15 patients with acute left-sided malignant large bowel obstruction. No acute procedure-related complication was observed. All the patients in group A

  11. Thermodynamics of phase coexistence and metal-nonmetal transition in mercury: assessment of effective potentials via expanded Wang-Landau simulations.

    PubMed

    Desgranges, Caroline; Delhommelle, Jerome

    2014-03-20

    We present molecular simulation results on the thermodynamics of phase transitions (specifically, the vapor-liquid and metal-nonmetal transitions) in mercury, as predicted by effective potential models. We use a recently developed method, known as Expanded Wang-Landau simulations, to determine the grand-canonical partition function of systems of mercury atoms. Using the statistical mechanics formalism, we are then able to determine all thermodynamic properties of the system, including the Gibbs free energy and entropy. Prior experimental and theoretical work has emphasized the strong interplay between the vapor-liquid coexistence and the metal-nonmetal transition. We therefore start by assessing the accuracy of the effective potentials considered in this work through a comparison to the available experimental data. We then analyze the thermodynamics of the nonmetal liquid-metal liquid transition, characterized by sharp variations in the rate of change of Gibbs free energy and enthalpy as a function of density. We also identify a crossover density (10.5 g/cm(3)) consistent with the results of recent ab initio calculations and with the experiment.

  12. Endovascular Exclusion of Visceral Artery Aneurysms with Stent-Grafts: Technique and Long-Term Follow-up

    SciTech Connect

    Rossi, Michele; Rebonato, Alberto Greco, Laura; Citone, Michele; David, Vincenzo

    2008-01-15

    This paper describes four cases of visceral artery aneurysms (VAAs) successfully treated with endovascular stent-grafts and discusses the endovascular approach to VAAs and the long-term results. Four balloon expandable stent-grafts were used to treat three splenic artery aneurysms and one bleeding common hepatic artery pseudoaneurysm. The percutaneous access site and the materials were chosen on the basis of CT angiography findings. In all cases the aneurysms were successfully excluded. In one case a splenic infarction occurred, with nonrelevant clinical findings. At 16- to 24-month follow-up three patients had patent stents and complete exclusion and shrinkage of the aneurysms. One patient died due to pancreatitis and sepsis, 16 days after successful stenting and exclusion of a bleeding pseudoaneurysm. We conclude that endovascular treatment using covered stent-grafts is a valid therapeutic option for VAAs. Multislice CT preoperative study helps in planning stent-graft positioning.

  13. PALMAZ stent in the treatment of peripheral arterial disease

    NASA Astrophysics Data System (ADS)

    Henry, Michel; Amor, Max; Ethevenot, Gerard; Henry, Isabelle; Amicabile, Claude; Beron, Richard; Mentre, Bernard; Allaoui, Mohamed

    1994-02-01

    To overcome problems associated with angioplasty, placement of a balloon-expandable vascular prosthesis was studied. Two hundred sixty-eight patients had a stent or stents implanted for reasons of restenosis, occlusion or dissection. One hundred forty-eight patients presented with iliac lesions, 108 with femoro-popliteal lesions and 12 patients had lesions within bypass grafts. Patients were followed up for an average of 19.89 months with angiographic, Doppler ultrasound and clinical evaluation. Only five cases of restenosis were not able to be corrected by secondary angioplasty. The primary patency rate at 3 years for iliac stents was 91%, and for femoropopliteal lesions was 72%. Secondary patency rates did not differ appreciable for femoropopliteal and iliac lesions and for stenoses and occlusions.

  14. Leo Stent for Endovascular Treatment of Broad-Necked and Fusiform Intracranial Aneurysms

    PubMed Central

    Juszkat, R.; Nowak, S.; Smól, S.; Kociemba, W.; Blok, T.; Zarzecka, A.

    2007-01-01

    Summary The advent of intracranial stents has widened the indications for endovascular treatment of broad-necked and fusiform aneurysms. Leo stent is a self-expandable, nitinol, braided stent dedicated to intracranial vessels. The aim of this study is to present our experience in endovascular treatment of broad-necked and fusiform intracranial aneurysms using self-expanding, nitinol Leo stents. Between February 2004 and November 2006, 25 broad-necked and three fusiform aneurysms in 28 patients were treated using Leo stents in our centre. There were 18 patients who experienced acute subarachnoid haemorrhage due to aneurysm rupture, two patients who experienced SAH at least 12 months ago and in eight patients aneurysms were found incidentally. Aneurysms were located as follows: internal carotid artery15, basilar artery5, basilar tip3, posterior inferior cerebral artery2, M1/M2 segment1, A2 segment1 and vertebral artery1. There were no difficulties with stent deployment and delivery. All patients after acute SAH (n=18) underwent stent implantation and coil embolization in one procedure. The remaining patients underwent coil embolization in a staged procedure. Immediate aneurysm occlusion of more than 95% was achieved in all patients who underwent stent placement and coil embolization in one procedure. There were three thromboembolic complications encountered in patients in an acute setting of SAH, preloaded only on acetylsalicylic acid. Use of abciximab led to patency within the stent and parent vessel. However, one of these patients presented rebleeding from the aneurysm during administration of abciximab and died. Application of Leo stents in cases of broadnecked and fusiform intracranial aneurysms is safe and effective with a low complication rate. PMID:20566117

  15. Geometry parameterization and multidisciplinary constrained optimization of coronary stents.

    PubMed

    Pant, Sanjay; Bressloff, Neil W; Limbert, Georges

    2012-01-01

    Coronary stents are tubular type scaffolds that are deployed, using an inflatable balloon on a catheter, most commonly to recover the lumen size of narrowed (diseased) arterial segments. A common differentiating factor between the numerous stents used in clinical practice today is their geometric design. An ideal stent should have high radial strength to provide good arterial support post-expansion, have high flexibility for easy manoeuvrability during deployment, cause minimal injury to the artery when being expanded and, for drug eluting stents, should provide adequate drug in the arterial tissue. Often, with any stent design, these objectives are in competition such that improvement in one objective is a result of trade-off in others. This study proposes a technique to parameterize stent geometry, by varying the shape of circumferential rings and the links, and assess performance by modelling the processes of balloon expansion and drug diffusion. Finite element analysis is used to expand each stent (through balloon inflation) into contact with a representative diseased coronary artery model, followed by a drug release simulation. Also, a separate model is constructed to measure stent flexibility. Since the computational simulation time for each design is very high (approximately 24 h), a Gaussian process modelling approach is used to analyse the design space corresponding to the proposed parameterization. Four objectives to assess recoil, stress distribution, drug distribution and flexibility are set up to perform optimization studies. In particular, single objective constrained optimization problems are set up to improve the design relative to the baseline geometry-i.e. to improve one objective without compromising the others. Improvements of 8, 6 and 15% are obtained individually for stress, drug and flexibility metrics, respectively. The relative influence of the design features on each objective is quantified in terms of main effects, thereby suggesting the

  16. Novel A20-gene-eluting stent inhibits carotid artery restenosis in a porcine model

    PubMed Central

    Zhou, Zhen-hua; Peng, Jing; Meng, Zhao-you; Chen, Lin; Huang, Jia-Lu; Huang, He-qing; Li, Li; Zeng, Wen; Wei, Yong; Zhu, Chu-Hong; Chen, Kang-Ning

    2016-01-01

    Background Carotid artery stenosis is a major risk factor for ischemic stroke. Although carotid angioplasty and stenting using an embolic protection device has been introduced as a less invasive carotid revascularization approach, in-stent restenosis limits its long-term efficacy and safety. The objective of this study was to test the anti-restenosis effects of local stent-mediated delivery of the A20 gene in a porcine carotid artery model. Materials and methods The pCDNA3.1EHA20 was firmly attached onto stents that had been collagen coated and treated with N-succinimidyl-3-(2-pyridyldithiol)propionate solution and anti-DNA immunoglobulin fixation. Anti-restenosis effects of modified vs control (the bare-metal stent and pCDNA3.1 void vector) stents were assessed by Western blot and scanning electron microscopy, as well as by morphological and inflammatory reaction analyses. Results Stent-delivered A20 gene was locally expressed in porcine carotids in association with significantly greater extent of re-endothelialization at day 14 and of neointimal hyperplasia inhibition at 3 months than stenting without A20 gene expression. Conclusion The A20-gene-eluting stent inhibits neointimal hyperplasia while promoting re-endothelialization and therefore constitutes a novel potential alternative to prevent restenosis while minimizing complications. PMID:27540277

  17. Comparing coronary stent material performance on a common geometric platform through simulated bench testing.

    PubMed

    Grogan, J A; Leen, S B; McHugh, P E

    2012-08-01

    Absorbable metallic stents (AMSs) are a newly emerging cardiovascular technology which has the potential to eliminate long-term patient health risks associated with conventional permanent stents. AMSs developed to date have consisted of magnesium alloys or iron, materials with inferior mechanical properties to those used in permanent stents, such as stainless steel and cobalt-chromium alloys. However, for AMSs to be feasible for widespread clinical use it is important that their performance is comparable to modern permanent stents. To date, the performances of magnesium, iron, and permanent stent materials have not been compared on a common stent platform for a range of stent performance metrics, such as flexibility, radial strength, and recoil. In this study, this comparison is made through simulated bench testing, based on finite-element modelling. The significance of this study is that it allows potential limitations in current AMS performance to be identified, which will aid in focusing future AMS design. This study also allows the identification of limitations in current AMS materials, thereby informing the on-going development of candidate biodegradable alloys. The results indicate that the AMSs studied here can match the recoil characteristics and radial strength of modern permanent stents; however, to achieve this, larger strut dimensions are required. It is also predicted that the AMSs studied are inferior to permanent stents in terms of maximum absolute curvature and longitudinal stiffness.

  18. Effect of force-induced mechanical stress at the coronary artery bifurcation stenting: Relation to in-stent restenosis

    SciTech Connect

    Lee, Cheng-Hung; Jhong, Guan-Heng; Hsu, Ming-Yi; Wang, Chao-Jan; Liu, Shih-Jung; Hung, Kuo-Chun

    2014-05-28

    The deployment of metallic stents during percutaneous coronary intervention has become common in the treatment of coronary bifurcation lesions. However, restenosis occurs mostly at the bifurcation area even in present era of drug-eluting stents. To achieve adequate deployment, physicians may unintentionally apply force to the strut of the stents through balloon, guiding catheters, or other devices. This force may deform the struts and impose excessive mechanical stresses on the arterial vessels, resulting in detrimental outcomes. This study investigated the relationship between the distribution of stress in a stent and bifurcation angle using finite element analysis. The unintentionally applied force following stent implantation was measured using a force sensor that was made in the laboratory. Geometrical information on the coronary arteries of 11 subjects was extracted from contrast-enhanced computed tomography scan data. The numerical results reveal that the application of force by physicians generated significantly higher mechanical stresses in the arterial bifurcation than in the proximal and distal parts of the stent (post hoc P < 0.01). The maximal stress on the vessels was significantly higher at bifurcation angle <70° than at angle ≧70° (P < 0.05). The maximal stress on the vessels was negatively correlated with bifurcation angle (P < 0.01). Stresses at the bifurcation ostium may cause arterial wall injury and restenosis, especially at small bifurcation angles. These finding highlight the effect of force-induced mechanical stress at coronary artery bifurcation stenting, and potential mechanisms of in-stent restenosis, along with their relationship with bifurcation angle.

  19. Preventing in-stent restenosis using lipoprotein (a), lipid and cholesterol adsorbent materials.

    PubMed

    Kazemian, Mohammad Reza; Solouk, Atefeh; Tan, Aaron; Seifalian, Alexander M

    2015-12-01

    Atherosclerosis is one of the major cause of mortality in developed countries. The characteristic lesion of atherosclerosis is the atheroma or plaque that forms through thickening of the inner layer of the vessel wall (called the intima). The development of stent in 1980s revolutionised treatment of cardiovascular diseases, including atherosclerosis. However the advent of stenting was hindered by the new problem of in-stent restenosis. It was demonstrated that in-stent restenosis was the result of a new pathology in the form of neointimal hyperplasia, which was a maladaptive healing response to bare-metal stent implantation. Recent evidence suggests that although drug-eluting stent (DES) have reduced restenosis rates, important concerns have been raised regarding increased late stent thrombosis, myocardial infarction and death. With advances in nanotechnology and smart materials, covered stents has been proposed to overcome this problem. This is due to in-stent late restenosis and thromboses are mainly caused by smooth muscle cells (SMC) proliferation. Studies showed that there is a relation between high low-density lipoprotein (LDL) and lipoprotein (a) [Lp(a)] level in blood stream and chance of in-stent restenosis, moreover studies show that Lp(a) could stimulate SMC proliferation. We hypothesis development of covered stent with novel design and use of smart materials which could adsorb cholesterol and prevent contact between Lp(a) and vessel wall to overcome problem indicated in DES. In addition cost of stents will significantly reduce by elimination of drugs as well as complex manufacturing of the drug incorporation.

  20. Newly designed “pieced” stent in a rabbit model of benign esophageal stricture

    PubMed Central

    Liu, Jin; Shang, Liang; Liu, Ji-Yong; Qin, Cheng-Yong

    2015-01-01

    AIM: To investigate a newly designed stent and its dilatation effect in a rabbit model of benign esophageal stricture. METHODS: Thirty-four New Zealand white rabbits underwent a corrosive injury in the middle esophagus for esophageal stricture formation. Thirty rabbits with a successful formation of esophageal strictures were randomly allocated into two groups. The control group (n = 15) was implanted with a conventional stent, and the study group (n = 15) was implanted with a detachable “pieced” stent. The study stent (30 mm in length, 10 mm in diameter) was composed of three covered metallic pieces connected by surgical suture lines. The stent was collapsed by pulling the suture lines out of the mesh. Two weeks after stricture formation, endoscopic placement of a conventional stent or the new stent was performed. Endoscopic extraction was carried out four weeks later. The extraction rate, ease of extraction, migration, complications, and survival were evaluated. RESULTS: Stent migration occurred in 3/15 (20%) animals in the control group and 2/15 (13%) animals in the study group; the difference between the two groups was not statistically significant. At the end of four weeks, the remaining stents were successfully extracted with the endoscope in 100% (11/11) of the animals in the study group, and 60% (6/10) of the animals in the control group; this difference was statistically significant (P < 0.05). There was no difference in the mean number of follow-up days between the control and study groups (25.33 vs 25.85). Minor bleeding was reported in five cases in the study group and four in the control group. There were no severe complications directly associated with stent implantation or extraction in either of the two groups. CONCLUSION: In this experimental protocol of benign esophageal strictures, the novel “pieced” stent demonstrated a superior removal rate with a similar migration rate compared to a conventional stent. PMID:26229404

  1. Delayed complications after flow-diverter stenting: reactive in-stent stenosis and creeping stents.

    PubMed

    Cohen, José E; Gomori, John Moshe; Moscovici, Samuel; Leker, Ronen R; Itshayek, Eyal

    2014-07-01

    We assessed the frequency and severity of changes in stent configuration and location after the treatment of intracranial aneurysms, and patterns of in-stent stenosis. We retrospectively reviewed data for consecutive aneurysm patients managed with endovascular implantation of flow-diverter stents (Silk Flow Diverter [Balt Extrusion, Montmorency, France] and Pipeline Embolization Device [ev3/Coviden, Minneapolis, MN, USA]) from October 2011 to July 2012. Routine 2, 6, 9-12, and 16-20 month follow-up angiograms were compared, with a focus on changes in stent configuration and location from immediately after deployment to angiographic follow-up, and the incidence and development of in-stent stenosis. Thirty-four patients with 42 aneurysms met inclusion criteria. The Silk device was implanted in 16 patients (47%, single device in 15), the Pipeline device in 18 (53%, single device in 16). On first follow-up angiography, in-stent stenosis was observed in 38% of Silk devices and 39% of Pipeline devices. In-stent stenosis was asymptomatic in 12 of 13 patients. One woman presented with transient ischemic attacks and required stent angioplasty due to end tapering and mild, diffuse in-stent stenosis. Configuration and location changes, including stent creeping and end tapering were seen in 2/16 patients (13%) with Silk devices, and 0/18 patients with Pipeline devices. We describe stent creeping and end tapering as unusual findings with the potential for delayed clinical complications. In-stent stenosis, with a unique behavior, is a frequent angiographic finding observed after flow-diverter stent implant. The stenosis is usually asymptomatic; however, close clinical and angiographic monitoring is mandatory for individualized management.

  2. Nanoporous CREG-Eluting Stent Attenuates In-Stent Neointimal Formation in Porcine Coronary Arteries

    PubMed Central

    Sun, Mingyu; Tao, Jie; Yan, Chenghui; Kang, Jian; Li, Shaohua

    2013-01-01

    Background The goal of this study was to evaluate the efficacy of a nanoporous CREG-eluting stent (CREGES) in inhibiting neointimal formation in a porcine coronary model. Methods In vitro proliferation assays were performed using isolated human endothelial and smooth muscle cells to investigate the cell-specific pharmacokinetic effects of CREG and sirolimus. We implanted CREGES, control sirolimus-eluting stents (SES) or bare metal stents (BMS) into pig coronary arteries. Histology and immunohistochemistry were performed to assess the efficacy of CREGES in inhibiting neointimal formation. Results CREG and sirolimus inhibited in vitro vascular smooth muscle cell proliferation to a similar degree. Interestingly, human endothelial cell proliferation was only significantly inhibited by sirolimus and was increased