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Sample records for expandable metal stent

  1. Expandable Metal Stents for the Palliation of Malignant Gastroduodenal Obstruction

    SciTech Connect

    Razzaq, Rubeena; Laasch, Hans-Ulrich; England, Ruth; Marriott, Angie; Martin, Derrick

    2001-09-15

    Purpose: Gastric outlet obstruction is a debilitating complication of upper gastrointestinal malignancy. We present our experience with insertion of self-expanding metal stents (SEMS).Methods: Twenty-eight patients were referred, stenting being attempted in 23. Two patients had esophageal Wallstents inserted through a gastrostomy; 21 had an endoscopic approach with enteral Wallstents.Results: One stent insertion failed, ten patients (45%) returned to a normal diet, ten patients (45%) managed semi-solid food and two patients (9%) had no significant improvement. No immediate complications were seen. One patient subsequently developed pancreatitis. Reintervention (4 stents, 1 jejunostomy, 1 gastro jejunostomy) was required in six of 22 patients (27%) for inadequate stent expansion (1), second stricture (2), stent migration (1), and tumor ingrowth (2). The mean survival was 95.4 days (SD 78.8 days, range 3-230 days). The mean follow-up time was 98.9 days (SD 86.7 days, range 3-309 days).Conclusions: SEMS are effective in palliating malignant gastric outlet obstruction. A combined endoscopic/fluoroscopic approach allows the most complete assessment of the stricture and removes the need for gastrostomy insertion. Careful assessment of the gastrointestinal tract distal to the lesion is important.

  2. Endoscopic palliation for pancreatic cancer with expandable metal stents.

    PubMed

    Spitz, J D; Arregui, M E

    2000-05-01

    Pancreatic cancer is generally not amenable to curative resection. Consequently, therapeutic efforts for these patients are most commonly directed at palliation of symptoms. Historically, surgery has been considered the most effective method of providing relief for biliary and/or enteric obstruction. However, less invasive methods have become available that can provide effective relief of jaundice and duodenal obstruction. Surgeons should still play an integral role in the management of these patients. We present a case report in which self-expanding metallic stents were used to relieve obstruction of the bile duct and duodenum in a patient with unresectable pancreatic cancer.

  3. Endoscopic Ultrasound-guided Antegrade Stenting in an Occluded Biliary Self-expandable Metal Stent

    PubMed Central

    Almadi, Majid A.; Eltayeb, Mohanned; Thaniah, Salem

    2016-01-01

    Endoscopic ultrasound-guided biliary drainage (EUS-BD) is an attractive option for patients who cannot undergo conventional endoscopic retrograde cholangiopancreatography (ERCP) and do not want surgery or percutaneous drainage procedures. We present the use of EUS-antegrade (EUS-AG) insertion of a self-expandable metal stent (SEMS) in a patient with a common hepatic duct cholangiocarcinoma, as well as a huge gastric lipoma, after recurrent biliary obstruction of a prior SEMS inserted via ERCP in the same session as a duodenal stent insertion for gastric outlet obstruction. PMID:27488330

  4. Polymeric photosensitizer-embedded self-expanding metal stent for repeatable endoscopic photodynamic therapy of cholangiocarcinoma.

    PubMed

    Bae, Byoung-chan; Yang, Su-Geun; Jeong, Seok; Lee, Don Haeng; Na, Kun; Kim, Joon Mee; Costamagna, Guido; Kozarek, Richard A; Isayama, Hiroyuki; Deviere, Jacques; Seo, Dong Wan; Nageshwar Reddy, D

    2014-10-01

    Photodynamic therapy (PDT) is a new therapeutic approach for the palliative treatment of malignant bile duct obstruction. In this study, we designed photosensitizer-embedded self-expanding nonvascular metal stent (PDT-stent) which allows repeatable photodynamic treatment of cholangiocarcinoma without systemic injection of photosensitizer. Polymeric photosensitizer (pullulan acetate-conjugated pheophorbide A; PPA) was incorporated in self-expanding nonvascular metal stent. Residence of PPA in the stent was estimated in buffer solution and subcutaneous implantation on mouse. Photodynamic activity of PDT-stent was evaluated through laserexposure on stent-layered tumor cell lines, HCT-116 tumor-xenograft mouse models and endoscopic intervention of PDT-stent on bile duct of mini pigs. Photo-fluorescence imaging of the PDT-stent demonstrated homogeneous embedding of polymeric Pheo-A (PPA) on stent membrane. PDT-stent sustained its photodynamic activities at least for 2 month. And which implies repeatable endoscopic PDT is possible after stent emplacement. The PDT-stent after light exposure successfully generated cytotoxic singlet oxygen in the surrounding tissues, inducing apoptotic degradation of tumor cells and regression of xenograft tumors on mouse models. Endoscopic biliary in-stent photodynamic treatments on minipigs also suggested the potential efficacy of PDT-stent on cholangiocarcinoma. In vivo and in vitro studies revealed our PDT-stent, allows repeatable endoscopic biliary PDT, has the potential for the combination therapy (stent plus PDT) of cholangiocarcinoma.

  5. 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.

  6. Evaluation of anti-migration properties of biliary covered self-expandable metal stents

    PubMed Central

    Minaga, Kosuke; Kitano, Masayuki; Imai, Hajime; Harwani, Yogesh; Yamao, Kentaro; Kamata, Ken; Miyata, Takeshi; Omoto, Shunsuke; Kadosaka, Kumpei; Sakurai, Toshiharu; Nishida, Naoshi; Kudo, Masatoshi

    2016-01-01

    AIM: To assess anti-migration potential of six biliary covered self-expandable metal stents (C-SEMSs) by using a newly designed phantom model. METHODS: In the phantom model, the stent was placed in differently sized holes in a silicone wall and retracted with a retraction robot. Resistance force to migration (RFM) was measured by a force gauge on the stent end. Radial force (RF) was measured with a RF measurement machine. Measured flare structure variables were the outer diameter, height, and taper angle of the flare (ODF, HF, and TAF, respectively). Correlations between RFM and RF or flare variables were analyzed using a linear correlated model. RESULTS: Out of the six stents, five stents were braided, the other was laser-cut. The RF and RFM of each stent were expressed as the average of five replicate measurements. For all six stents, RFM and RF decreased as the hole diameter increased. For all six stents, RFM and RF correlated strongly when the stent had not fully expanded. This correlation was not observed in the five braided stents excluding the laser cut stent. For all six stents, there was a strong correlation between RFM and TAF when the stent fully expanded. For the five braided stents, RFM after full stent expansion correlated strongly with all three stent flare structure variables (ODF, HF, and TAF). The laser-cut C-SEMS had higher RFMs than the braided C-SEMSs regardless of expansion state. CONCLUSION: RF was an important anti-migration property when the C-SEMS did not fully expand. Once fully expanded, stent flare structure variables plays an important role in anti-migration. PMID:27570427

  7. Self-expanding metal stents for palliative treatment of malignant biliary and duodenal stenoses.

    PubMed

    Maetani, I; Ogawa, S; Hoshi, H; Sato, M; Yoshioka, H; Igarashi, Y; Sakai, Y

    1994-10-01

    Patients with malignant biliary stenosis due to pancreatic head cancer often have the associated problem of duodenal obstruction. We report here the case of a 78-year-old woman with this clinical situation, who was treated with self-expanding Gianturco metal stents placed in the distal common bile duct and, nine months later, placed in the descending duodenum. The patient's frequent vomiting resolved, and she was able to tolerate peroral solid food; jaundice also decreased (bilirubin pre-stenting: 7.8; post-stenting: 1.2). Self-expanding metal stents therefore appear to be effective for the palliative treatment of malignant duodenal stenosis as well as biliary stenosis.

  8. Effect of the Palmaz balloon-expandable metallic stent in the trachea of pigs.

    PubMed

    Ruegemer, J L; Perkins, J A; Azarow, K S; O'Bryant, L K; Nielsen, R E; Thomas, R W

    1999-07-01

    Endoscopically placed airway stents offer a viable option in primary or adjunctive treatment of severe pediatric tracheobronchial stenoses. Optimistic clinical reports substantiate the need for experimental studies to more effectively evaluate their clinical role. Development of an animal model comparable with the pediatric airway, amenable to endoscopic instrumentation, and capable of assessing effect on growth was the purpose of this pilot project. Nine 4-week-old piglets underwent endoscopic midtracheal placement of the balloon-expandable Palmaz metallic stent. Initial expansion and stent position were verified fluoroscopically and by direct videobronchoscopy. Serial endoscopic examination and stent reexpansion were performed 2 and 4 weeks after stent insertion. Animal weight, clinical tolerance, tracheal growth, and stent integrity were observed. Tracheal inflammation was evaluated grossly and by objective histopathologic criteria. Successful endotracheal stent placement and expansion were accomplished in all piglets. One pig died of anesthesia complications less than 24 hours after stent insertion. The remaining pigs exhibited excellent clinical tolerance through experiment completion. No detrimental effect on growth was noted, and effective dilatation of the stented tracheal region was observed. Stent incorporation was evident with significant mucosal ingrowth. Inflammation in the form of nonobstructing granulation tissue was present, and no evidence of necrosis or cartilage invasion was evident. The piglet trachea appears to be an excellent model for evaluation of expandable metallic airway stents in management of congenital and acquired tracheobronchial stenoses.

  9. Self-Expandable Metallic Stent Placement in Malignant Gastric Outlet Obstruction: A Comparison Between 2 Brands of Stents.

    PubMed

    Ye, Bing-Wei; Lee, Kuei-Chuan; Hsieh, Yun-Cheng; Li, Chung-Pin; Chao, Yee; Hou, Ming-Chih; Lin, Han-Chieh

    2015-07-01

    Malignant gastric outlet obstruction is a late complication of intraabdominal malignancy. Self-expandable metallic stent placement has been a safe palliative treatment to relieve obstructive symptoms. We aimed to assess the efficacy and safety of metallic stents in our patients and analyzed the clinical outcome of different brands. Seventy-one patients with inoperable gastric outlet obstruction receiving WallFlex enteral stents (WallFlex group) or Bonastents (Bonastent group) since April 2010 were analyzed retrospectively. The overall technical and clinical success rates of stent placement were 100% and 93%, respectively. The baseline characteristics and clinical outcomes including procedure-related complications, restenosis, and reintervention rates were comparable between the 2 groups. However, the Bonastent group had a higher rate of stent fracture than the WallFlex group (13.3% vs 0%, P = 0.03). The mean duration of overall stent patency was 132.7 days. The mean duration of survival was 181.9 days. Resumption of regular diet or low residual diet at day 7 after stent insertion predicted stent patency (hazard ratio [HR]: 0.28, P = 0.01). Cancer with gastric origin (HR: 0.25, P = 0.045) and poststent chemotherapy (HR: 0.38, P = 0.006) predicted lower mortality; however, peritoneal carcinomatosis (HR: 3.09, P = 0.04) correlated with higher mortality. Metallic stent placement is a safe and effective method for relieving gastric outlet obstruction. Except higher rate of stent fracture in the Bonastent group, there is no significant difference in clinical outcomes between the Bonastent group and the WallFlex group.

  10. Palliative therapy using polyurethane-covered self-expandable metallic stents for malignant esophageal strictures: experiences in six patients.

    PubMed

    Kato, M; Saji, S; Kanematsu, M; Hoshi, H; Ishiguchi, T; Kunieda, K; Takao, H; Sugiyama, Y

    1996-12-01

    To evaluate the utility and limitations of palliative stenting with polyurethane-covered self-expandable metallic stents, 6 patients (3 males and 3 females ranging in age from 58-85 [mean 72.1] years) with malignant esophageal strictures were treated with these stents between April 1993 and October 1995. Three had esophageal carcinoma, two had gastric carcinoma and one had lung carcinoma. Song-type self-expandable metallic stents were inserted by intubation under local laryngeal anesthesia. A retriever was attached in 4 stents and an anti-reflux mechanism was attached in 2 stents placed over the esophagocardiac strictures. The stents were placed successfully in all patients, and no major complication related to intubation was encountered. All the stents fully expanded within 3 days after insertion. The grade of dysphagia was improved in 5 (83%) of the 6 patients. One stent was extracted using a retriever in one patient with no improvement. No reflux symptoms were observed in 2 patients whom received stents with an anti-reflux mechanism. No blockage of the stent due to food impaction or secondary stricture occurred in any patient during the observation period. One stent migrated into the stomach in one patient 27 days after insertion. Esophageal stenting with polyurethane-covered self-expandable metallic stents is a relatively safe and effective palliation for malignant esophageal strictures. PMID:9001352

  11. Role of self-expanding metal stents in the management of variceal haemorrhage: Hype or hope?

    PubMed Central

    Hogan, Brian J; O’Beirne, James P

    2016-01-01

    Despite the advances of medical, endoscopic and radiological therapy over recent years the mortality rates of acute variceal haemorrhage are still 16%-20% and the medium term outcome has not improved in the last 25 years. Early transjugular intrahepatic portosystemic shunt has proved to be an effective therapy for selected groups of patients with a high risk of re-bleeding and moderate liver disease. However, there is an unmet need for a therapy that can be applied in patients with a high risk of re-bleeding and advanced liver disease either as definitive therapy or as a bridge to permanent therapy. Self-expanding metal stents can be placed without the need for endoscopic or fluoroscopic control and, once in place, will provide effective haemostasis and allow a route for oral fluids and nutrition. They can remain in place whilst liver function recovers and secondary prophylaxis is initiated. We review the results of 6 case series including a total of 83 patients and the first randomised controlled trial of self-expanding metal stents vs balloon tamponade (BT) in the management of refractory variceal haemorrhage. We report that self-expanding metal stents provide effective haemostasis and perform better than BT in refractory bleeding, where they are associated with fewer complications. Whilst the most effective place for self-expanding metal stents in the management algorithm needs to be determined by further randomised controlled trials, currently they provide an effective alternative to BT in selected patients. PMID:26788260

  12. Role of self-expanding metal stents in the management of variceal haemorrhage: Hype or hope?

    PubMed

    Hogan, Brian J; O'Beirne, James P

    2016-01-10

    Despite the advances of medical, endoscopic and radiological therapy over recent years the mortality rates of acute variceal haemorrhage are still 16%-20% and the medium term outcome has not improved in the last 25 years. Early transjugular intrahepatic portosystemic shunt has proved to be an effective therapy for selected groups of patients with a high risk of re-bleeding and moderate liver disease. However, there is an unmet need for a therapy that can be applied in patients with a high risk of re-bleeding and advanced liver disease either as definitive therapy or as a bridge to permanent therapy. Self-expanding metal stents can be placed without the need for endoscopic or fluoroscopic control and, once in place, will provide effective haemostasis and allow a route for oral fluids and nutrition. They can remain in place whilst liver function recovers and secondary prophylaxis is initiated. We review the results of 6 case series including a total of 83 patients and the first randomised controlled trial of self-expanding metal stents vs balloon tamponade (BT) in the management of refractory variceal haemorrhage. We report that self-expanding metal stents provide effective haemostasis and perform better than BT in refractory bleeding, where they are associated with fewer complications. Whilst the most effective place for self-expanding metal stents in the management algorithm needs to be determined by further randomised controlled trials, currently they provide an effective alternative to BT in selected patients.

  13. Cholecystoduodenal fistula: A complication of inserted self-expandable metallic bilitary stents

    SciTech Connect

    Nishida, Hirotoshi; Inoue, Hiroki; Ueno, Kazuto; Nagata, Yukitaka; Kato, Takeshi; Miyazono, Nobuaki; Nakajo, Masayuki

    1998-05-15

    We encountered a case of hepatic hilar cholangiocarcinoma resulting in cholecystoduodenal fistula after insertion of self-expandable metallic biliary stents (EMBSs). To our knowledge, there has been no report of cholecystoduodenal fistula after insertion of EMBSs. This case suggests that immediate gallbladder decompression may be necessary if acute cholecystitis occurs after insertion of EMBSs.

  14. Cholecystoduodenal Fistula: A Complication of Inserted Self-Expandable Metallic Biliary Stents

    SciTech Connect

    Nishida, Hirotoshi; Inoue, Hiroki; Ueno, Kazuto; Nagata, Yukitaka; Kato, Takeshi; Miyazono, Nobuaki; Nakajo, Masayuki

    1998-05-15

    We encountered a case of hepatic hilar cholangiocarcinoma resulting in cholecystoduodenal fistula after insertion of self-expandable metallic biliary stents (EMBSs). To our knowledge, there has been no report of cholecystoduodenal fistula after insertion of EMBSs. This case suggests that immediate gallbladder decompression may be necessary if acute cholecystitis occurs after insertion of EMBSs.

  15. Removal of Endobronchially Placed Vascular Self-Expandable Metallic Stent Using Flexible Bronchoscopy.

    PubMed

    Kremens, Karol

    2016-04-01

    Self-expanding metallic stents (SEMS) are commonly placed in malignant airway obstruction and sometimes in benign obstruction. Complications from SEMS placement are common, especially after 30 days from deployment. SEMS removal can be complicated and often involves significant resources. We report a case of a 78-year-old man with small cell carcinoma who underwent placement of a Luminexx endovascular stent in his right main stem bronchus, complicated by stent migration after initiation of chemotherapy. Stent removal was performed by flexible bronchoscopy, utilizing forceps inserted via a working channel, as well as a goose neck snare operated parallel to the bronchoscope. The patient was discharged the same day with no complications. PMID:27197344

  16. [Trimming with argon plasma of self-expanding metal stents: report of 7 cases].

    PubMed

    Jury, Gastón; Amieva, Leandro; López, Fagalde Rafael; Jury, Rubén

    2014-06-01

    The use of self-expandable enteral stents for palliation of malignant stenosis may present the complication of concealing the ampulla of Vater behind the metallic mesh. Anchoring in the duodenal wall (distal or partial migration) may also be a complication of biliary metallic stents and therefore may cause difficulty in gaining access to the biliary tract. In these cases of difficult access, a fenestration on the prosthesis ( biliary or enteral) can be created to allow reaching the obstructed biliary tract by means of argon plasma (AP). Were retrospectively analysed 7 cases. Under endoscopic vision, AP was directed to filgurate and cut 6 biliary prosthesis and a duodenal stent. Fulguration and cut of biliary stent was performed in 5 cases of distal partial migration and cholangitis. In one case of obstruction caused by distal migration inside the duodenal stent light, cutting of the biliary stent was performed. A window was created in the enteral prosthesis in order to access the ampulla of Vater and place a biliary tract prosthesis. All cases were resolved successfully and without complications. We conclude that the use of AP to fulgurate and cut nitinol prosthesis was effective and presented no complications in this series.

  17. Efficacy of Self-Expandable Metallic Stent Inserted for Refractory Hemorrhage of Duodenal Cancer.

    PubMed

    Orii, Takashi; Karasawa, Yukihiko; Kitahara, Hiroe; Yoshimura, Masaki; Okumura, Motohiro

    2016-01-01

    Because of advances in the technology of gastrointestinal endoscopy and improvements in the quality of stents, it has become routine to place a stent as palliative therapy for malignant gastrointestinal obstruction. On the other hand, stent placement for malignant gastrointestinal hemorrhage has scarcely been reported, although it may be performed for hemorrhage of the esophageal varicose vein. We recently experienced a patient with refractory hemorrhage from an unresectable duodenal cancer who underwent placement of a self-expandable metallic stent (SEMS) and thereafter had no recurrence of the hemorrhage. A 46-year-old man underwent laparotomy to radically resect a cancer in the third portion of the duodenum, which invaded widely to the superior mesenteric vein and its branches and was considered unresectable. After stomach-partitioning gastrojejunostomy was performed, chemotherapy was initiated according to the regimen of chemotherapy of far advanced gastric cancer. One year and 4 months after induction of chemotherapy, gastrointestinal hemorrhage occurred. Upper gastrointestinal endoscopy revealed the hemorrhage oozing from the duodenal cancer, and endoscopic hemostasis, such as injection of hypertonic saline epinephrine and argon plasma coagulation, was unsuccessful. Twenty days after emergence of the hemorrhage, an endoscopic covered SEMS was placed with confirmation by fluoroscopy. Immediately after placement of the stent, the tarry stool stopped and the anemia ceased to progress. The recurrence of the hemorrhage has not been confirmed without migration of the stent. SEMS is an effective hemostatic procedure for malignant refractory hemorrhage. PMID:27403118

  18. Efficacy of Self-Expandable Metallic Stent Inserted for Refractory Hemorrhage of Duodenal Cancer

    PubMed Central

    Orii, Takashi; Karasawa, Yukihiko; Kitahara, Hiroe; Yoshimura, Masaki; Okumura, Motohiro

    2016-01-01

    Because of advances in the technology of gastrointestinal endoscopy and improvements in the quality of stents, it has become routine to place a stent as palliative therapy for malignant gastrointestinal obstruction. On the other hand, stent placement for malignant gastrointestinal hemorrhage has scarcely been reported, although it may be performed for hemorrhage of the esophageal varicose vein. We recently experienced a patient with refractory hemorrhage from an unresectable duodenal cancer who underwent placement of a self-expandable metallic stent (SEMS) and thereafter had no recurrence of the hemorrhage. A 46-year-old man underwent laparotomy to radically resect a cancer in the third portion of the duodenum, which invaded widely to the superior mesenteric vein and its branches and was considered unresectable. After stomach-partitioning gastrojejunostomy was performed, chemotherapy was initiated according to the regimen of chemotherapy of far advanced gastric cancer. One year and 4 months after induction of chemotherapy, gastrointestinal hemorrhage occurred. Upper gastrointestinal endoscopy revealed the hemorrhage oozing from the duodenal cancer, and endoscopic hemostasis, such as injection of hypertonic saline epinephrine and argon plasma coagulation, was unsuccessful. Twenty days after emergence of the hemorrhage, an endoscopic covered SEMS was placed with confirmation by fluoroscopy. Immediately after placement of the stent, the tarry stool stopped and the anemia ceased to progress. The recurrence of the hemorrhage has not been confirmed without migration of the stent. SEMS is an effective hemostatic procedure for malignant refractory hemorrhage. PMID:27403118

  19. Self-expanding metal stenting for obstructing left colon cancer: A district hospital experience.

    PubMed

    Harilingam, Mohan Raj; Khushal, Amjad; Aikoye, Abdulmalik

    2016-07-01

    Stenting of malignant colonic obstructions using self-expanding metal stents (SEMS) is commonly used for palliation and can be used as an interim procedure prior to definitive surgery. We retrospectively reviewed prospectively collected data from all consecutive colonic stenting procedures undertaken between September 2007 and December 2014 at a district general hospital. Technical and clinical success rates, mortality, colonic perforation, and other complications were documented and analyzed. Sixty-four colonic stenting procedures were undertaken. Fifty-three (83 %) were for palliation and eleven (17 %) were performed as a bridge to definitive surgery. Technical (98.4 %) and clinical (89.9 %) success rates were excellent. The single documented failure was secondary to complete luminal obstruction. Three stent occlusions (4.6 %), one colonic perforation (1.5 %), and one migration were encountered. There were no procedure-related deaths. Colonic stenting for obstructing left-sided colon cancer is a safe and effective procedure, even in the district general hospital setting. The use of SEMS as a bridge to elective surgery balances surgical and oncological considerations and, therefore, is most appropriate for high surgical risk patients in this setting. PMID:27448435

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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. PMID:27100431

  5. Gastrotracheal fistula: Treatment with a covered elf-expanding Y-shaped metallic stent

    PubMed Central

    Wang, Fei; Yu, Hong; Zhu, Ming-Hui; Li, Quan-Peng; Ge, Xian-Xiu; Nie, Jun-Jie; Miao, Lin

    2015-01-01

    A 67-year-old man had a sev-ere cough and pulmonary infection for 1 wk before seeking evaluation at our hospital. He had undergone esophagectomy with gastric pull-up and radiotherapy for esophageal cancer 3 years previously. After admission to our hospital, gastroscopy and bronchoscopy revealed a fistulous communication between the posterior tracheal wall near the carina and the upper residual stomach. We measured the diameter of the trachea and bronchus and determined the site and size of the fistula using multislice computed tomography and gastroscopy. A covered self-expanding Y-shaped metallic stent was implanted into the trachea and bronchus. Subsequently, the fistula was closed completely. The patient tolerated the stent well and had good palliation of his symptoms. PMID:25624743

  6. Self-expanding metallic stent placement with an exaggerated 5-cm proximal tumor covering for palliation of esophageal cancer

    PubMed Central

    Tahiri, Mehdi; Ferraro, Pasquale; Duranceau, André; Berthiaume, Melanie; Thiffault, Vicky; Liberman, Moishe

    2015-01-01

    Background The study aimed to evaluate the short- and long-term outcomes with a technique of self-expanding metallic stent insertion in palliative esophageal cancer patients. We hypothesized that a systematic attempt at exaggerated (5 cm) proximal tumor covering could prevent both stent migration and tumor overgrowth/undergrowth. Methods We reviewed retrospectively all patients who underwent esophageal stenting for palliation of malignant dysphagia over a 24-month period. Consecutive patients were identified from a prospective thoracic surgery interventional endoscopy database. This technique consisted of endoscopic stent insertion with the aim of landing the proximal portion of the stent 5 cm cephalad to the proximal extent of the tumor. All patients were followed at one month post-procedure and every three months thereafter, until death. Short- and long-term complications associated with the procedure and mortality were evaluated. Results Forty seven patients underwent endoscopic insertion of an esophageal stent in the context of an inoperable esophageal cancer using this technique over a 24-month period. The mean age was 70.4±9.6 years. Four (8.5%) patients underwent re-stenting due to proximal tumor overgrowth. No stent migration, perforation, tumor ingrowth or stent occlusion was reported. The mean patient survival was 146±26.5 days. Conclusions Esophageal stent insertion under endoscopic guidance with proximal tumor covering of 5 cm is effective and safe. No cases of stent migration and a low incidence of tumor overgrowth/undergrowth were observed with this technique. PMID:26126578

  7. Self-expandable metallic stents for palliation of patients with malignant gastric outlet obstruction caused by stomach cancer

    PubMed Central

    Kim, Tae Oh; Kang, Dae Hwan; Kim, Gwang Ha; Heo, Jeong; Song, Geun Am; Cho, Mong; Kim, Dong Heon; Sim, Mun Sup

    2007-01-01

    AIM: To ascertain clinical outcome and complications of self-expandable metal stents for endoscopic palliation of patients with malignant obstruction of the gastrointestinal (GI) tract. METHODS: A retrospective review was performed throughout August 2000 to June 2005 of 53 patients with gastric outlet obstruction caused by stomach cancer. All patients had symptomatic obstruction including nausea, vomiting, and decreased oral intake. All received self-expandable metallic stents. RESULTS: Stent implantation was successful in all 53 (100%) patients. Relief of obstructive symptoms was achieved in 43 (81.1%) patients. No immediate stent-related complications were noted. Seventeen patients had recurrent obstruction (tumor ingrowth in 14 patients, tumor overgrowth in 1 patient, and partial distal stent migration in 2 patients). The mean survival was 145 d. Median stent patency time was 187 d. CONCLUSION: Endoscopic placement of self-expandable metallic stents is a safe and effective treatment for the palliation of patients with inoperable malignant gastric outlet obstruction caused by stomach cancer. PMID:17352023

  8. Combined Placement of Covered Self-Expanding Metallic Stents and Nasojejunal Tube for Managing Large Lower Esophageal Perforations

    PubMed Central

    Rana, Surinder S; Gupta, Rajesh; Dahiya, Divya; Behera, Arunanshu; Bhasin, Deepak K

    2014-01-01

    Covered self-expanding metallic stents (cSEMSs) have emerged as effective treatment option for esophageal perforations. However, the large lower esophageal perforations where the cSEMS is placed across gastroesophageal junction have lower healing rates because refluxed gastric contents constantly irritate perforation and also there is increased risk of stent migration. Moreover, gastric mucosa tends to prolapse into lumen of lower end of stent causing its obstruction, leading to seepage of saliva and fluids from upper end of stent even in the patients who are on parenteral nutrition. We present our experience of a novel technique of combined cSEMS and nasojejunal tube (NJT) placement in four patients (two males) with benign large lower esophageal perforations. The NJT was placed through the stent into the jejunum through which patients were given enteral feeding. The stents were placed 5 - 21 days after esophageal perforation with the size of perforation ranging from 4 to 6 cm. As the NJT formed a loop in stomach, it prevented migration of stent. And also its presence in lumen of stent prevented its obstruction by prolapsing gastric mucosa, thereby preventing seepage of saliva and fluids from side of stent. Both stents and NJT were removed after 6 weeks and leak closed in all patients. Combined cSEMS and NJT placement seems to be safe and effective for treating large lower esophageal perforations. NJT placement seems to decrease risk of migration, prevents seepage of fluids and permits early enteral nutrition, thereby improving the healing rates.

  9. Self-expandable metal stents for achalasia: Thinking out of the box!

    PubMed Central

    Sioulas, Athanasios D; Malli, Chrysoula; Dimitriadis, George D; Triantafyllou, Konstantinos

    2015-01-01

    Achalasia is a primary motor disorder of the esophagus diagnosed manometrically in the clinical setting of dysphagia to both solids and liquids. Currently established treatment options include pneumatic dilation, laparoscopic Heller myotomy, botulinum toxin injection performed endoscopically, oral agents that relax the lower esophageal sphincter and esophagectomy for refractory, end-stage disease. Despite their effectiveness, a significant proportion of patients eventually relapses and needs retreatment. In this setting, several new techniques are under investigation promising future enrichment of our therapeutic armamentarium for achalasic patients. Among them, peroral endoscopic myotomy and self-expandable metal stents placed across the gastro-esophageal junction represent the most encouraging modalities, as initial studies assessing their efficacy and safety indicate. This review highlights the role of self-expandable metal stents in the management of patients with achalasia. Their possible position in the therapeutic algorithm of achalasia along with established and novel techniques is also assessed. Finally, the need for large prospective randomized trials is underlined in order to elucidate the numerous relevant issues. PMID:25610533

  10. Implantation of self-expanding metal stent in the treatment of severe bleeding from esophageal ulcer after endoscopic band ligation.

    PubMed

    Mishin, I; Ghidirim, G; Dolghii, A; Bunic, G; Zastavnitsky, G

    2010-09-01

    Endoscopic variceal ligation is superior to sclerotherapy because of its lower rebleeding and complication rates. However, ligation may be associated with life-threatening bleeding from postbanding esophageal ulcer. We report a case of a 49-year-old male with massive hemorrhage from esophageal ulcer on 8th day after successful band ligation of bleeding esophageal varices caused by postviral liver cirrhosis (Child-Pugh class C). A removable polyurethane membrane-covered self-expanding metal stent (SX-ELLA stent Danis, 135 mm × 25 mm, ELLA-CS, Hradec-Kralove, Czech Republic) was inserted in ICU for preventing fatal hemorrhage. Complete hemostasis was achieved and stent was removed after 8 days without rebleeding or any complications. To the best of our knowledge, this is the first report in English literature regarding life-threatening hemorrhage from postbanding esophageal ulcer successfully treated by self-expanding metal stent in a patient with portal hypertension.

  11. Endoscopic Ultrasound-Guided Self-Expandable Metal Stent Placement for the Treatment of Infected Pancreatic Pseudocysts

    PubMed Central

    Masrour, Farbod; Mallat, Damien

    2014-01-01

    The standard endoscopic ultrasound (EUS) approach of cystogastrostomy involves the use of series of plastic pigtail stents that are placed through the wall of the cyst. The use of a single stent has also been described in the literature. Here we describe five cases of EUS-guided cystogastrostomy with irrigation of infected pancreatic pseudocysts using a single self-expandable metal stent (SEMS). To our knowledge this has not been described in the literature in the United States. This novice approach will have significant implications in the management of infected pseudocysts with a lower morbidity, mortality and overall cost compared to conventional management such as surgery or percutaneous drainage.

  12. Fully Covered Self-Expandable Metal Stents for Treatment of Post-Sphincterotomy Bleeding

    PubMed Central

    Samie, Ahmed Abdel; Theilmann, Lorenz

    2012-01-01

    Endoscopic biliary sphincterotomy (ES) is the cornerstone of therapeutic endoscopic retrograde cholangiopancreatography (ERCP); however, serious complications are not uncommon. Post-sphincterotomy bleeding is one of the most frequent complications following ES and may occur in up to 10% of the patients. The spectrum of presentation may range from self-limited to severe live threatening hemorrhage. Different endoscopic treatment options are available. Angiographic embolisation and surgery are preserved for refractory cases not controlled by endoscopic means. Recently, completely covered self-expandable metal stents (CSEMS) have been applied to achieve hemostasis in severe post-sphincterotomy bleeding not controlled by other measures. We present our experience with this method to control delayed bleeding after ES in two patients requiring continuous therapeutic anticoagulation due to high cardiovascular embolic risk.

  13. Fully Covered Self-Expandable Metal Stents for Treatment of Malignant Biliary Strictures due to Pancreatic Carcinoma

    PubMed Central

    Samie, Ahmed Abdel; Stumpf, Michael; Theilmann, Lorenz

    2012-01-01

    Background Transpapillary stents are used to treat malignant biliary strictures. However, there are different stent types and data are controversial in respect to success and complications. Recently, completely covered self-expandable metal stents (CSEMS) have become available. The aim of this study is to present a consecutive series of CSEMS placed to decompress the bile duct in malignant stenosis due to pancreatic carcinoma and to evaluate the effectiveness, complication rate and extractability of these devices. Methods We retrospectively reviewed the courses of 27 consecutive patients who received CSEMS due to malignant biliary strictures because of pancreatic carcinoma regardless of presumed resectability between January 2010 and May 2012 in our endoscopic unit. Results A total of 27 patients (12 male and 15 female) were included in the study. The mean age of the patients was 75 years. Endoscopic retrograde cholangiopancreatography (ERCP), endoscopic sphincterotomy (ES) and stent placement were successful at first attempt in all cases. The mean length of the stenosis was 20 mm. In 24 patients (89%) a stent length of 4 cm was sufficient to bridge the stenosis. In three cases a stent length of 6 cm was necessary. Drainage was achieved as monitored by a significant decrease or normalization of bilirubin in all cases (mean bilirubin 8.5 mg/dL and 1.5 mg/dL before and after stent placement respectively), 15 patients underwent surgery with pylorus preserving duodenopancreatectomy. In all patients who underwent surgery stents could be removed during the operation without difficulties. Leakage of the biliodigestive anastomosis occurred in one patient (6.6%). Four (15%) of the 27 patients developed complications related to the endoscopic procedure and/or stent placement respectively (cholecystitis in two patients, stent occlusion in one patient, and post-sphincterotomy bleeding in one patient). Conclusion The prolonged patency, extractability, and low complication rate

  14. Temporary placement of fully covered self-expandable metal stents for the treatment of benign biliary strictures

    PubMed Central

    Chaput, Ulriikka; Vienne, Ariane; Audureau, Etienne; Bauret, Paul; Bichard, Philippe; Coumaros, Dimitri; Napoléon, Bertrand; Ponchon, Thierry; Duchmann, Jean-Christophe; Laugier, René; Lamouliatte, Hervé; Védrenne, Bruno; Gaudric, Marianne; Chaussade, Stanislas; Robin, Françoise; Leblanc, Sarah

    2015-01-01

    Background Endoscopic treatment of benign biliary strictures (BBS) can be challenging. Objective To evaluate the efficacy of fully covered self-expandable metal stents (FCSEMS) in BBS. Methods Ninety-two consecutive patients with BBS (chronic pancreatitis (n = 42), anastomotic after liver transplantation (n = 36), and post biliary surgical procedure (n = 14)) were included. FCSEMS were placed across strictures for 6 months before endoscopic extraction. Early success rate was defined as the absence of biliary stricture or as a minimal residual anomaly on post-stent removal endoscopic retrograde cholangiopancreatography (ERCP). Secondary outcomes were the final success and stricture recurrence rates as well as procedure-related morbidity. Results Stenting was successful in all patients. Stenting associated complications were minor and occurred in 22 (23.9%) patients. Migration occurred in 23 (25%) patients. Stent extraction was successful in all but two patients with proximal stent migration. ERCP after the 6 months stenting showed an early success in 84.9% patients (chronic pancreatitis patients: 94.7%, liver transplant: 87.9%, post-surgical: 61.5%) (p = 0.01). Final success was observed in 57/73 (78.1%) patients with a median follow-up of 12 ± 3.56 months. Recurrence of biliary stricture occurred in 16/73 (21.9%) patients. Conclusions FCSEMS placement is efficient for patients with BBS, in particular for chronic pancreatitis patients. Stent extraction after 6 months indwelling, although generally feasible, may fail in a few cases. PMID:27403307

  15. Biliary self-expandable metallic stent for unresectable malignant distal biliary obstruction: which is better: covered or uncovered?

    PubMed

    Isayama, Hiroyuki; Nakai, Yousuke; Kogure, Hirofumi; Yamamoto, Natsuyo; Koike, Kazuhiko

    2013-05-01

    Self-expandable metallic stents (SEMS) are a widely accepted biliary endoprosthesis for patients with unresectable malignant distal biliary obstruction. There are two types of SEMS: covered and uncovered. Uncovered SEMS (UCSEMS) embed into the biliary wall due to their mesh structure and self-expandability, and are resistant to migration. However, the disadvantage of UCSEMS is occlusion due to tumor ingrowth (TI) via the stent mesh, and TI is the main cause of UCSEMS occlusion. To overcome this, covered SEMS (CSEMS) were developed and showed longer patency than UCSEMS. However, migration due to the non-embedded stent body is the main cause of CSEMS dysfunction. There are some randomized studies comparing CSEMS and UCSEMS; however, the results are different according to each study. From one meta-analysis, CSEMS showed longer patency than UCSEMS. A literature review revealed that covered SEMS showed longer patency than UCSEMS. Some studies cannot clearly demonstrate the superiority of CSEMS, as the CSEMS used did not prevent TI or migration. Mechanical properties of SEMS may influence the occurrence of complications. A recent clinical study comparing the Covered Wallstent and the Covered WallFlex revealed superiority of the WallFlex for the prevention of migration. Reducing the axial force and increasing the radial force may lead to good results. Migration of CSEMS should be prevented by taking into consideration the mechanical properties of stents and development of anti-migration systems.

  16. Self-Expanding Metallic Stents for Palliation and as a Bridge to Minimally Invasive Surgery in Colorectal Obstruction

    PubMed Central

    Barbosa, Guilherme; Zeichen, Marianna S.; Mata, Wilmer N.; Maciel, Victor; Plasencia, Gustavo; Hartmann, Rene F.; Viamonte, Manuel; Fogel, Roberto

    2013-01-01

    Background and Objectives: Acute colorectal obstruction is a potentially life-threatening emergency that requires immediate surgical treatment. Emergency procedures had an associated mortality rate of 10% to 30%. This encouraged development of other options, most notably self-expanding metallic stents. The primary endpoint of this study to is to report our group's experience. Methods: We performed a retrospective review of 37 patients who underwent self-expanding metallic stent placement for colorectal obstruction between July 2000 and May 2012. Data collected were age, comorbidities, diagnosis, intent of intervention (palliative vs bridge to surgery), complications, and follow-up. Results: The study comprised 21 men (56.76%) and 16 women (43.24%), with a mean age of 67 years. The intent of the procedure was definitive treatment in 22 patients (59.46%) and bridge to surgery in 15 (40.54%). The highest technical success rate was at the rectosigmoid junction (100%). The causes of technical failure were inability of the guidewire to traverse the stricture and bowel perforation related to stenting. The mean follow-up period was 9.67 months. Pain and constipation were the most common postprocedure complications. Discussion: The use of a self-expanding metallic stent has been shown to be effective for palliation of malignant obstruction. It is associated with a lower incidence of intensive care unit admission, shorter hospital stay, lower stoma rate, and earlier chemotherapy administration. Laparoscopic or robotic surgery can then be performed in an elective setting on a prepared bowel. Therefore the patient benefits from advantages of the combination of 2 minimally invasive procedures in a nonemergent situation. Further large-scale prospective studies are necessary. PMID:23925013

  17. Endoscopic transluminal pancreatic necrosectomy using a self-expanding metal stent and high-flow water-jet system

    PubMed Central

    Hritz, István; Fejes, Roland; Székely, András; Székely, Iván; Horváth, László; Sárkány, Ágnes; Altorjay, Áron; Madácsy, László

    2013-01-01

    Walled-off pancreatic necrosis and a pancreatic abscess are the most severe complications of acute pancreatitis. Surgery in such critically ill patients is often associated with significant morbidity and mortality within the first few weeks after the onset of symptoms. Minimal invasive approaches with high success and low mortality rates are therefore of considerable interest. Endoscopic therapy has the potential to offer safe and effective alternative treatment. We report here on 3 consecutive patients with infected walled-off pancreatic necrosis and 1 patient with a pancreatic abscess who underwent direct endoscopic necrosectomy 19-21 d after the onset of acute pancreatitis. The infected pancreatic necrosis or abscess was punctured transluminally with a cystostome and, after balloon dilatation, a non-covered self-expanding biliary metal stent was placed into the necrotic cavity. Following stent deployment, a nasobiliary pigtail catheter was placed into the cavity to ensure continuous irrigation. After 5-7 d, the metal stent was removed endoscopically and the necrotic cavity was entered with a therapeutic gastroscope. Endoscopic debridement was performed via the simultaneous application of a high-flow water-jet system; using a flush knife, a Dormia basket, and hot biopsy forceps. The transluminal endotherapy was repeated 2-5 times daily during the next 10 d. Supportive care included parenteral antibiotics and jejunal feeding. All patients improved dramatically and with resolution of their septic conditions; 3 patients were completely cured without any further complications or the need for surgery. One patient died from a complication of prolonged ventilation severe bilateral pneumonia, not related to the endoscopic procedure. No procedure related complications were observed. Transluminal endoscopic necrosectomy with temporary application of a self-expanding metal stent and a high-flow water-jet system shows promise for enhancing the potential of this endoscopic

  18. 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.

  19. 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).

  20. Self-Expandable Metal Stents for Persisting Esophageal Variceal Bleeding after Band Ligation or Injection-Therapy: A Retrospective Study

    PubMed Central

    Müller, Martin; Seufferlein, Thomas; Perkhofer, Lukas; Wagner, Martin; Kleger, Alexander

    2015-01-01

    Background and Study Aims Despite a pronounced reduction of lethality rates due to upper gastrointestinal bleeding, esophageal variceal bleeding remains a challenge for the endoscopist and still accounts for a mortality rate of up to 40% within the first 6 weeks. A relevant proportion of patients with esophageal variceal bleeding remains refractory to standard therapy, thus making a call for additional tools to achieve hemostasis. Self-expandable metal stents (SEMS) incorporate such a tool. Methods We evaluated a total number of 582 patients admitted to our endoscopy unit with the diagnosis “gastrointestinal bleeding” according to our documentation software between 2011 and 2014. 82 patients suffered from esophageal variceal bleeding, out of which 11 cases were refractory to standard therapy leading to SEMS application. Patients with esophageal malignancy, fistula, or stricture and a non-esophageal variceal bleeding source were excluded from the analysis. A retrospective analysis reporting a series of clinically relevant parameters in combination with bleeding control rates and adverse events was performed. Results The initial bleeding control rate after SEMS application was 100%. Despite this success, we observed a 27% mortality rate within the first 42 days. All of these patients died due to non-directly hemorrhage-associated reasons. The majority of patients exhibited an extensive demand of medical care with prolonged hospital stay. Common complications were hepatic decompensation, pulmonary infection and decline of renal function. Interestingly, we found in 7 out of 11 patients (63.6%) stent dislocation at time of control endoscopy 24 h after hemostasis or at time of stent removal. The presence of hiatal hernia did not affect obviously stent dislocation rates. Refractory patients had significantly longer hospitalization times compared to non-refractory patients. Conclusions Self-expandable metal stents for esophageal variceal bleeding seem to be safe and

  1. Treatment of esophageal anastomotic leakage with self-expanding metal stents: analysis of risk factors for treatment failure

    PubMed Central

    Persson, Saga; Rouvelas, Ioannis; Kumagai, Koshi; Song, Huan; Lindblad, Mats; Lundell, Lars; Nilsson, Magnus; Tsai, Jon A.

    2016-01-01

    Background and study aim: The endoscopic placement of self-expandable metallic esophageal stents (SEMS) has become the preferred primary treatment for esophageal anastomotic leakage in many institutions. The aim of this study was to investigate possible risk factors for failure of SEMS-based therapy in patients with esophageal anastomotic leakage. Patients and methods: Beginning in 2003, all patients with an esophageal leak were initially approached and assessed for temporary closure with a SEMS. Until 2014, all patients at the Karolinska University Hospital with a leak from an esophagogastric or esophagojejunal anastomosis were identified. Data regarding the characteristics of the patients and leaks and the treatment outcomes were compiled. Failure of the SEMS treatment strategy was defined as death due to the leak or a major change in management strategy. The risk factors for treatment failure were analyzed with simple and multivariable logistic regression statistics. Results: A total of 447 patients with an esophagogastric or esophagojejunal anastomosis were identified. Of these patients, 80 (18 %) had an anastomotic leak, of whom 46 (58 %) received a stent as first-line treatment. In 29 of these 46 patients, the leak healed without any major change in treatment strategy. Continuous leakage after the application of a stent, decreased physical performance preoperatively, and concomitant esophagotracheal fistula were identified as independent risk factors for failure with multivariable logistic regression analysis. Conclusion: Stent treatment for esophageal anastomotic leakage is successful in the majority of cases. Continuous leakage after initial stent insertion, decreased physical performance preoperatively, and the development of an esophagotracheal fistula decrease the probability of successful treatment. PMID:27092321

  2. SU-E-T-115: Dose Perturbation Study of Self-Expandable Metal and Polyester Esophageal Stents in Proton Therapy Beams

    SciTech Connect

    Lee, S; Li, Z; Jalaj, S; McGaw, C; B K, John; J S, Scolapio; J C, Munoz

    2014-06-01

    Purpose: This work investigates dose perturbations due to Self-expandable metal and polyester esophageal stents undergoing proton radiotherapy for esophageal cancer. Methods: Five commercially available esophageal stents made of nitinol (Evolution, Wallflex and Ultraflex), stainless steel (Z-Stent) and polyester (Polyflex) were tested. Radiochromic film (GafChromic EBT3 film, Ashland, Covington, KY) wrapped around a stent and a 12cc syringe was irradiated with 2CGE (Cobalt Gray Equivalent) of proton beam in a custom fabricated acrylic phantom. An air-hollow syringe simulates the esophagus. Results: The Z-stent created the largest dose perturbations ranges from -14.5% to 6.1% due to the steel composition. The WallFlex, Evolution and Ultraflex stents produced the dose perturbation ranges of (−9.2%∼8.6%), (−6.8%∼5.7%) and (−6.2%∼6.2%), respectively. The PolyFlex stent contains the radiopaque tungsten markers located top, middle and bottom portions. When the focal cold spots induced by the markers were excluded in the analysis, the dose perturbation range was changed from (−11.6%∼6.4%) to (−0.6%∼5.0%). Conclusion: The magnitude of dose perturbation is related to material of a metallic stent. The non-metallic stent such as PolyFlex shows relatively lower dose perturbation than metallic stents except a radiopaque marker region. Overall Evolution and Ultraflex stent appear to be less dose perturbations. The largest dose perturbations (cold spots) were located at both edges of stents in distal area for the single proton beam irradiation study. The analysis of more than two proton beam which is more typical clinical beam arrangement would be necessary to minimize the doe perturbation effect in proton ratiotherapy.

  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. Comparative retrospective study on the use of plastic prostheses and self-expanding metal stents in the palliative treatment of malignant strictures of the esophagus and cardia.

    PubMed

    Mosca, F; Consoli, A; Stracqualursi, A; Persi, A; Portale, T R

    2003-01-01

    Palliative treatment of malignant strictures of the esophagus and cardia is usually carried out by the endoscopic placement of a prosthesis. The aim of this retrospective study was to evaluate short- and long-term outcomes of the use of expandable stents, compared with conventional plastic prostheses. One hundred and thirteen endoscopic intubations were carried out in 120 patients affected by malignant stenosis of the esophagus and cardia using plastic prosthesis and self-expanding metal stents. Dysphagia was scored according to Atkinson and Ferguson's classification and the preoperative median score (3.6) was comparable in both groups. The technical success rate was 94.4% with plastic prosthesis and 93.7% with self-expanding metal stent while the functional success rate was, respectively, 85.2% and 88.8%. Three deaths occurred with plastic prostheses (4.4%), while no deaths were observed with metal stents. A comparative analysis of the results of this study suggests that the endoscopic placement of self-expanding metal stents is effective and safe and has to be preferred to the conventional plastic prosthesis for easier implantation and lower morbidity. PMID:12823210

  5. 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

  6. Fully covered self-expandable metal stent in the treatment of postsurgical colorectal diseases: outcome in 29 patients

    PubMed Central

    Cereatti, Fabrizio; Fiocca, Fausto; Dumont, Jean-Loup; Ceci, Vincenzo; Vergeau, Bertrand-Marie; Tuszynski, Thierry; Meduri, Bruno; Donatelli, Gianfranco

    2016-01-01

    Background: Self-expandable metal stent (SEMS) placement is a minimally invasive treatment for palliation of malignant colorectal strictures and as a bridge to surgery. However, the use of SEMS for benign colorectal diseases is controversial. The purpose of this retrospective study is to evaluate the efficacy and safety of fully covered SEMS (FCSEMS) placement in postsurgical colorectal diseases. Methods: From 2008 to 2014, 29 patients with 32 FCSEMS deployment procedures were evaluated. The indications for stent placement were: 17 anastomotic strictures (3/17 presented complete closure of the anastomosis); four anastomotic leaks; seven strictures associated with anastomotic leak; and one rectum-vagina fistula. Results: Clinical success was achieved in 18 out of 29 patients (62.1%) being symptom-free at an average of 19 months. In the remaining 11 patients (37.9%), a different treatment was needed: four patients required multiple endoscopic dilations, 4 patients colostomy confection, one patient definitive ileostomy and three patients revisional surgery. The FCSEMS were kept in place for a mean period of 34 (range: 6–65) days. Major complications occurred in 12 out of 29 patients (41.4%) and consisted of stent migration. Minor complications included two cases of transient fever, eight cases of abdominal or rectal pain, and one case of tenesmus. Conclusion: FCSEMS are considered a possible therapeutic option for treatment of postsurgical strictures and leaks. However, their efficacy in guaranteeing long-term anastomotic patency and leak closure is moderate. A major complication is migration. The use of FCSEMS for colonic postsurgical pathologies should be carefully evaluated for each patient. PMID:26929780

  7. Treatment of malignant gastric outlet obstruction with endoscopically placed self-expandable metal stents.

    PubMed

    Gaidos, Jill K J; Draganov, Peter V

    2009-09-21

    Malignant gastroduodenal obstruction can occur in up to 20% of patients with primary pancreatic, gastric or duodenal carcinomas. Presenting symptoms include nausea, vomiting, abdominal distention, pain and decreased oral intake which can lead to dehydration, malnutrition, and poor quality of life. Endoscopic stent placement has become the primary therapeutic modality because it is safe, minimally invasive, and a cost-effective option for palliation. Stents can be successfully deployed in the majority of patients. Stent placement appears to lead to a shorter time to symptomatic improvement, shorter time to resumption of an oral diet, and shorter hospital stays as compared with surgical options. Recurrence of the obstructive symptoms resulting from stent occlusion, due to tumor ingrowth or overgrowth, can be successfully treated with repeat endoscopic stent placement in the majority of the cases. Both endoscopic stenting and surgical bypass are considered palliative treatments and, to date, no improvement in survival with either modality has been demonstrated. A tailored therapeutic approach, taking into consideration patient preferences and involving a multidisciplinary team including the therapeutic endoscopist, surgeon, medical oncologist, radiation therapist, and interventional radiologist, should be considered in all cases. PMID:19764086

  8. Self-expandable metallic stents in the treatment of post-esophagogastrostomy/post-esophagoenterostomy fistula.

    PubMed

    Nowakowski, P; Ziaja, K; Ludyga, T; Kuczmik, W; Biolik, G; Cwik, P; Ziaja, D

    2007-01-01

    Esophageus or gaster resection in patients with malignant disease is still a treatment of choice. It is obvious that each surgical procedure in these patients carries some possibility of complications. Esophageo-gastric or esophageo-jejuno anastomosis has a 4-27% frequency of fistula occurrence. All these result in 65% mortality in cases of poorer prognosis. The aim of this paper is not to present all types of complications but to objectively analyse the usefulness of the covered stent placement in the treatment of anastomotic fistulas. We present six patients who were treated for postoperative fistula of esophageo-gastric anastomosis (1 case) or esophageo-jejuno anastomosis (5 cases). All patients were treated with stapler suture for digestive tract reconstruction after malignancy removal during the primary surgical procedure. Signs and symptoms of suture leak between 5-8 days post-surgery were observed. Conservative therapy was not effective. Thus a new method of treatment was employed - covered stent placement. The procedure was performed under X-ray control. In all treated patients there was change for the better and quick reduction of secretion from the fistulas was observed. All patients were discharged from the department after several days and all had survived at 30 days follow-up. Covered esophageal stent placement seems to be a safe and promising method of treatment for patients with anastomotic fistula which significantly reduces mortality and improves quality of live. Our experiences confirms that of other investigators.

  9. [Extraordinary role of self-expanding metal stent (SEMS) in the malignant colorectal obstruction: different care in two cases].

    PubMed

    Siquini, Walter; Macarri, Giampiero; Freddara, Umberto; Stortoni, Pierpaolo; Ridolfo, Raffaella; Petrolati, Paolo; Fianchini, Aroldo; Landi, Edoardo

    2007-01-01

    The colorectal cancer presents with bowel obstruction in 10%-30% of patients. Established treatment of this evolutive condition, until 15 years ago, was emergency surgery. Primary resection with or without ileostomy, staged resection, Hartmann's procedure, or definitive colostomy are the therapeutical options. There is ongoing controversy on the best procedure to apply, because the choice depends on the patient's condition, age, electrolyte imbalances, nutritional status, obstructional grade, comorbidity and surgeon's attitude. However, the obstruction and the emergency operation add risk of complications and mortality instead of elective surgery. The efficacy of self-expanding metal stent to solve the obstruction had recently changed the management of malignant luminal obstruction: it is safe, effective, with very low mortality, low morbidity and also cheap. In the inoperable cases it represents the first line therapy avoiding the colostomy. In the operable patients, instead of two-step surgery, the SEMS had to be preferred because is a one-time and election surgery and avoid colostomy too, even if temporary. SEMS versus emergency primary surgery, without randomized and controlled study, allows a safer single-staged surgery. Finally it improves the quality of life avoiding colostomy, and reducing operative risk. We present two different use of SEMS: the palliation in inoperable patient and the "bridge to surgery" in critical obstructed patient.

  10. Uncovered Self-Expanding Metal Stent (SEMS) Four Years After Placement for Long-Term Treatment of a Benign Colonic Obstruction

    PubMed Central

    Lewis, Ayanna; Buscaglia, Jonathan M.

    2014-01-01

    Self-expanding metal stents (SEMS) have emerged as an alternative to surgery in the treatment of malignant colorectal obstructions. There is limited data about their use for benign colonic obstructions, especially in regards to safety and long-term patency. We present a case in which long-term SEMS placement proved to be a durable option for over 4 years in a patient with a benign colonic stricture. PMID:26157878

  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. Square Stent: A New Self-Expandable Endoluminal Device and Its Applications

    SciTech Connect

    Pavcnik, Dusan; Uchida, Barry; Timmermans, Hans; Keller, Frederick S.; Roesch, Josef

    2001-07-15

    The square stent is a new, simply constructed, self-expanding device that has recently been described. Compared with other stents, the square stent has a minimal amount of metal and thus requires a smaller-diameter catheter for introduction. Despite the small amount of metal present, the square stent has adequate expansile force. We have been evaluating the square stent for various interventional applications. In addition to the basic square stent, combinations of square stents and coverings for square stents were developed and evaluated to expand its uses and indications. One of the coverings tested is a new biomaterial: small intestinal submucosa (SIS). This paper will discuss the various applications of the square stent, which include a retrievable inferior vena cava filter, vascular occluder, graft adapter, and venous and aortic valves. In addition, we will review the important properties of SIS as a covering for the square stent.

  13. Post-biliary sphincterotomy bleeding despite covered metallic stent deployment

    PubMed Central

    Donatelli, Gianfranco; Cereatti, Fabrizio; Dumont, Jean-Loup; Dhumane, Parag; Tuszynski, Thierry; Vergeau, Bertrand Marie; Meduri, Bruno

    2016-01-01

    Objectives: Several endoscopic techniques have been proposed for the management of post-sphincterotomy bleeding. Lately, self-expandable metal stents deployment has gained popularity especially as a rescue therapy when other endoscopic techniques fail. Methods-results: We report the case report of a massive post-sphincterotomy bleeding in a patient with a self-expandable metal stent in the biliary tree. Despite the presence of a correctly positioned self-expandable metal stent, a new endoscopic session was required to control the bleeding. Conclusions: Self-expandable metal stent may be useful to manage post-endoscopic sphincterotomy bleeding. However, up to now there is no specifically designed self-expandable metal stent for such complication. Large new designed self-expandable metal stent may be a useful tool for biliary endoscopist. PMID:27489716

  14. 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.

  15. Endoscopic ultrasound (EUS)-guided transhepatic anterograde self-expandable metal stent (SEMS) placement across malignant biliary obstruction.

    PubMed

    Nguyen-Tang, T; Binmoeller, K F; Sanchez-Yague, A; Shah, J N

    2010-03-01

    Endoscopic retrograde cholangiopancreatography (ERCP) with placement of self-expandable metal stents (SEMS) for palliation of malignant obstruction may not be possible in patients with an inaccessible biliary orifice. Endoscopic ultrasound (EUS)-guided drainage methods may be useful in this setting. This study aimed to determine the outcomes of EUS-guided anterograde SEMS placement across malignant strictures in patients with an inaccessible biliary orifice. Over a 2-year period, procedural and outcomes data on all patients undergoing EUS-guided anterograde SEMS drainage after failed ERCP were prospectively entered into a database and reviewed. Five patients underwent EUS-guided anterograde SEMS. Indications included: advanced pancreatic cancer (n = 3), metastatic cancer (n = 1), and anastomotic stricture (n = 1). The biliary orifice could not be reached endoscopically due to duodenal stricture (n = 4) or inaccessible hepaticojejunostomy (n = 1). EUS-guided punctures were performed transgastrically into left intrahepatic ducts (n = 4) or transbulbar into the common bile duct (n = 1). Guide wires were passed and SEMS were successfully deployed across strictures in an anterograde fashion in all patients. Jaundice resolved and serum bilirubin levels decreased in all cases. No procedure-related complications were noted during a mean follow-up of 9.2 months. EUS-guided anterograde SEMS placement appears to be a safe and efficient technique for palliation of biliary obstruction in patients with an endoscopically inaccessible biliary orifice. The procedure can be performed at the time of failed standard ERCP, and provides an alternative drainage option to percutaneous or surgical decompression and to EUS-guided creation of bilioenteric fistulae.

  16. Basic Knowledge about Metal Stent Development.

    PubMed

    Jeong, Seok

    2016-03-01

    Biliary self-expandable metal stents (SEMS), a group of non-vascular stents, have been used in the palliative management of biliary obstruction around the world. However, there are still unmet needs in the clinical application of biliary SEMS. Comprehensive understanding of the SEMS is required to resolve the drawbacks and difficulties of metal stent development. The basic structure of SEMS, including the materials and knitting methods of metal wires, covering materials, and radiopaque markers, are discussed in this review. What we know about the physical and mechanical properties of the SEMS is very important. With an understanding of the basic knowledge of metal stents, hurdles such as stent occlusion, migration, and kinking can be overcome to develop more ideal SEMS.

  17. Basic Knowledge about Metal Stent Development

    PubMed Central

    Jeong, Seok

    2016-01-01

    Biliary self-expandable metal stents (SEMS), a group of non-vascular stents, have been used in the palliative management of biliary obstruction around the world. However, there are still unmet needs in the clinical application of biliary SEMS. Comprehensive understanding of the SEMS is required to resolve the drawbacks and difficulties of metal stent development. The basic structure of SEMS, including the materials and knitting methods of metal wires, covering materials, and radiopaque markers, are discussed in this review. What we know about the physical and mechanical properties of the SEMS is very important. With an understanding of the basic knowledge of metal stents, hurdles such as stent occlusion, migration, and kinking can be overcome to develop more ideal SEMS. PMID:27000423

  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. 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

  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.

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

    PubMed

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

    2013-06-16

    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.

  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. Transhepatic contemporary palliation of biliary and duodenal stenoses by means of metallic stents.

    PubMed

    Cozzi, G; Chiaraviglio, F; Bonfanti, G; Civelli, E M

    2004-01-01

    We describe the treatment of a stenosing lesion of the horizontal duodenum by means of a large-bore metallic stent inserted percutaneously in a patient with transhepatic biliary drainage. In the same session, we used an expandable metallic stent in the biliary tree to relieve jaundice. We recommend the transhepatic approach for duodenal metallic stent insertion in patients with percutaneous biliary drainage.

  6. [An Analysis of Placement of a Self-Expanding Metallic Stent as Bridge to Surgery for Surgical Resection of StageⅣ Obstructive Colorectal Cancers].

    PubMed

    Kawahara, Yohei; Terada, Itsuro; Terai, Shiro; Watanabe, Toshifumi; Amaya, Koji; Yamamoto, Seiichi; Kaji, Masahide; Maeda, Kiichi; Shimizu, Koichi

    2015-11-01

    In our institution, placement of a self-expanding metallic stent (SEMS) for obstructive colorectal cancer to avoid emergency operations, namely as a bridge to surgery (BTS), was introduced in April 2012. Here, we assess the efficacy and safety of pre-operative SEMS placement for treatment of Stage Ⅳ obstructive colorectal cancer. We analyzed a total of 44 cases of Stage Ⅳ colorectal cancer, which consisted of 13 obstructive cases that were surgically resected following SEMS placement as BTS (BTS group), and 31 cases that were resected in elective operations without pre-operative SEMS placement (Ope group), from April 2012 to August 2014. None of the patients had any adverse events during the SEMS procedure or after SEMS placement, and all patients of BTS group could undergo the planned operations after sufficient decompression. In the postoperative period, 1 patient of BTS group (7.7%) had anastomosis bleeding, but no other complications, including anastomosis leakage, were observed in BTS group. However more progressive primary tumors were resected in BTS group (p=0.0115), there were no significant differences for post-operative course between the 2 groups; this indicated avoiding high-risk emergency operations contributed to adequate short-term outcomes in BTS group comparable to those in Ope group. SEMS placement as BTS could be performed safely for Stage Ⅳ obstructive colorectal cancer cases, and was 1 of the effective strategies for local treatment. PMID:26805087

  7. In situ cooling with ice water for the easier removal of self-expanding nitinol stents

    PubMed Central

    Merkel, Daniel; Brinkmann, Eckhard; Wiens, Daniel; Derwahl, Karl-Michael

    2015-01-01

    Background: It is yet to be determined what effects temperature has on the properties of nitinol in order to simplify the process of removing nitinol self-expanding metal stents (SEMS). Materials and methods: We describe the procedure for removal of SEMS in a total of 11 cases with 9 patients. A study involving cooling of nitinol stents in situ with ice water just before their removal was attempted. Results: All stents were removed successfully. In partially covered and in fully covered stents, the stent rigidity was noticeably reduced following cooling. Stent removal was performed by inversion, which was achieved by pulling on the stent from its distal end. No adverse events were observed during this trial. Conclusion: The higher pliability of the stents after ice-water cooling facilitates stent removal. With this method, a mobilization of all stents by the invagination technique was achieved. The separation of the uncoated stent ends from the intestinal wall by the invagination technique, as well as the mucosal vasoconstriction resulting from the cooling, lead to an easier SEMS removal and may serve to prevent severe bleeding of the mucosal wall during this process. PMID:26134772

  8. Past, Present, and Future of Gastrointestinal Stents: New Endoscopic Ultrasonography-Guided Metal Stents and Future Developments

    PubMed Central

    Lee, Hee Seung; Chung, Moon Jae

    2016-01-01

    Innovations in stent technology and technological advances in endoscopic ultrasonography have led to rapid expansion of their use in the field of gastrointestinal diseases. In particular, endoscopic ultrasonography-guided metal stent insertion has been used for the management of pancreatic fluid collection, bile duct drainage, gallbladder decompression, and gastric bypass. Endoscopic ultrasonography-guided drainage of intra-abdominal fluid collections using a plastic or metal stent is well established. Because of the various limitations—such as stent migration, injury and bleeding in the lumen—recently developed, fully covered self-expanding metal stents or lumen-apposing metal stents have been introduced for those fluids management. This article reviews the recent literature on newly developed endoscopic ultrasonography-guided metal stents and the efficacy thereof. PMID:27000424

  9. Past, Present, and Future of Gastrointestinal Stents: New Endoscopic Ultrasonography-Guided Metal Stents and Future Developments.

    PubMed

    Lee, Hee Seung; Chung, Moon Jae

    2016-03-01

    Innovations in stent technology and technological advances in endoscopic ultrasonography have led to rapid expansion of their use in the field of gastrointestinal diseases. In particular, endoscopic ultrasonography-guided metal stent insertion has been used for the management of pancreatic fluid collection, bile duct drainage, gallbladder decompression, and gastric bypass. Endoscopic ultrasonography-guided drainage of intra-abdominal fluid collections using a plastic or metal stent is well established. Because of the various limitations-such as stent migration, injury and bleeding in the lumen-recently developed, fully covered self-expanding metal stents or lumen-apposing metal stents have been introduced for those fluids management. This article reviews the recent literature on newly developed endoscopic ultrasonography-guided metal stents and the efficacy thereof. PMID:27000424

  10. Stenting for malignant ureteral obstruction: Tandem, metal or metal-mesh stents.

    PubMed

    Elsamra, Sammy E; Leavitt, David A; Motato, Hector A; Friedlander, Justin I; Siev, Michael; Keheila, Mohamed; Hoenig, David M; Smith, Arthur D; Okeke, Zeph

    2015-07-01

    Extrinsic malignant compression of the ureter is not uncommon, often refractory to decompression with conventional polymeric ureteral stents, and frequently associated with limited survival. Alternative options for decompression include tandem ureteral stents, metallic stents and metal-mesh stents, though the preferred method remains controversial. We reviewed and updated our outcomes with tandem ureteral stents for malignant ureteral obstruction, and carried out a PubMed search using the terms "malignant ureteral obstruction," "tandem ureteral stents," "ipsilateral ureteral stents," "metal ureteral stent," "resonance stent," "silhouette stent" and "metal mesh stent." A comprehensive review of the literature and summary of outcomes is provided. The majority of studies encountered were retrospective with small sample sizes. The evidence is most robust for metal stents, whereas only limited data exists for tandem or metal-mesh stents. Metal and metal-mesh stents are considerably more expensive than tandem stenting, but the potential for less frequent stent exchanges makes them possibly cost-effective over time. Urinary tract infections have been associated with all stent types. A wide range of failure rates has been published for all types of stents, limiting direct comparison. Metal and metal-mesh stents show a high incidence of stent colic, migration and encrustation, whereas tandem stents appear to produce symptoms equivalent to single stents. Comparison is difficult given the limited evidence and heterogeneity of patients with malignant ureteral obstruction. It is clear that prospective, randomized studies are necessary to effectively scrutinize conventional, tandem, metallic ureteral and metal-mesh stents for their use in malignant ureteral obstruction.

  11. 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.

  12. 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.

  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. 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.

  15. Transjugular intrahepatic portosystemic shunting (TIPS) with balloon-expandable and self-expanding stents: Technical and clinical aspects after 3 1/2 years' experience

    SciTech Connect

    Tesdal, I. Kaare; Jaschke, Werner; Buehler, Mathias; Adamus, Ralf; Filser, Thomas; Holm, Eggert; Georgi, Max

    1997-01-15

    Purpose. To evaluate prospectively our experience with transjugular intrahepatic portosystemic shunt (TIPS) using four different metallic stents. Methods. Between November 1991 and April 1995, 57 patients (41 men and 16 women; age 35-72 years, mean 54 years) underwent the TIPS procedure. Techniques for portal vein localization before and during TIPS were fluoroscopy, computed tomography (CT) studies, wedged hepatic venography, arterial portography, and ultrasound. After predilation we deployed balloon-expandable (n=48) and self-expanding (n=45) metallic stents. Fifteen patients underwent variceal embolization. Initial follow-up angiograms (mean 6.9 months, range 3-24 months) were obtained in 39 of these patients. Results. Fifty-three patients (93%) had successful TIPS placement. The mean decrease in portal pressure was 42.7%. Besides fluoroscopy, the most helpful techniques for portal vein localization were venography and CT. Residual stenosis (n=1) and late shortening (n=4) of Wallstents resulted in shunt dysfunction. The technical problems encountered with the Palmaz stent resulted from its lack of flexibility. We combined balloon-expandable and self-expanding stents in 12 patients. The 30-day and late follow-up (mean 11.9 months) percutaneous reintervention rates were 11.3% and 64.2%, respectively. There were no clinically significant complications related to the TIPS insertions. Conclusion. An ideal stent does not exist for TIPS, and the authors recommend combining a Palmaz stent with a flexible self-expanding stent.

  16. 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.

  17. Virtual optimization of self-expandable braided wire stents.

    PubMed

    De Beule, Matthieu; Van Cauter, Sofie; Mortier, Peter; Van Loo, Denis; Van Impe, Rudy; Verdonck, Pascal; Verhegghe, Benedict

    2009-05-01

    At present, the deployment of self-expandable braided stents has become a common and widely used minimally invasive treatment for stenotic lesions in the cardiovascular, gastrointestinal and respiratory system. To improve these revascularization procedures (e.g. increase the positioning accuracy) the optimal strategy lies in the further development of the stent design. In the context of optimizing braided stent designs, computational models can provide an excellent research tool complementary to analytical models. In this study, a finite element based modelling strategy is proposed to investigate and optimize the mechanics of braided stents. First a geometrical and finite element model of a braided Urolume endoprosthesis was built with the open source pyFormex design tool. The results of the reference simulation of the Urolume stent are in close agreement with both analytical and experimental data. Subsequently, a simplex-based design optimization algorithm automatically adjusts the reference Urolume geometry to facilitate precise positioning by reducing the foreshortening with 20% while maintaining the radial stiffness. Therefore, the proposed modelling strategy appears to be a promising optimization methodology in braided stent design.

  18. 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.

  19. Treatment of an iatrogenic vertebral artery laceration with the Symbiot self expandable covered stent.

    PubMed

    Katsaridis, Vasilios; Papagiannaki, Chrysanthi; Violaris, Constantinos

    2007-07-01

    Vertebral artery laceration is difficult to treat surgically. Endovascular treatment with balloon expandable covered stents often fails due to their rigidity and poor navigability. We present a case of iatrogenic vertebral artery laceration where endovascular treatment with a balloon expandable covered stent failed. Eventually a self expandable symbiot covered stent was deployed over the laceration, securing hemostasis and preserving the vessel patency. The newer self expandable covered stents seem promising in the treatment of vertebral artery injury.

  20. Pancreatitis-Associated Splenic Artery Pseudoaneurysm: Endovascular Treatment with Self-Expandable Stent-Grafts

    SciTech Connect

    Brountzos, Elias N.; Vagenas, Kostantinos; Apostolopoulou, Sotiria C.; Panagiotou, Irene; Lymberopoulou, Dimitra; Kelekis, Dimitrios A.

    2003-02-15

    We present a patient with a splenic arterypseudoaneurysm (SAPA) treated with placement of self-expandable stent-grafts. The procedure was complicated by stent-graft migration,but successful management resulted in lasting exclusion of the SAPA,while the patency of the splenic artery was preserved. This is the first report of self-expandable stent-graft treatment of SAPA.

  1. Fluoroscopy Guided Transurethral Placement of Ureteral Metallic Stents

    PubMed Central

    Myung Gyu, Song; Seo, Tae Seok; Park, Cheol Min; Choi, Jae Woong; Lee, Jong Mee; Park, Yang Shin

    2015-01-01

    Ureteral stent exchange is usually performed under both fluoroscopic and cystoscopic guidance. We experienced two cases with retrograde placement of metallic ureteral stent via urethra under fluoroscopic guidance. When patients with double-J ureteral stent (DJUS)have symptom and want to change DJUS to metallic stent, fluoroscopic guided transurethral placement of ureteral metallic stent is a good option as alternative of cystoscopic procedure or percutaneous procedure through percutaneous nephrostomy tract. PMID:26557281

  2. 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.

  3. Clinical outcomes of self-expandable stent placement for benign esophageal diseases: A pooled analysis of the literature

    PubMed Central

    van Halsema, Emo E; van Hooft, Jeanin E

    2015-01-01

    AIM: To analyze the outcomes of self-expandable stent placement for benign esophageal strictures and benign esophageal leaks in the literature. METHODS: The PubMed, Embase and Cochrane databases were searched for relevant articles published between January 2000 and July 2014. Eight prospective studies were identified that analyzed the outcomes of stent placement for refractory benign esophageal strictures. The outcomes of stent placement for benign esophageal leaks, perforations and fistulae were extracted from 20 retrospective studies that were published after the inclusion period of a recent systematic review. Data were pooled and analyzed using descriptive statistics. RESULTS: Fully covered self-expandable metal stents (FC SEMS) (n = 85), biodegradable (BD) stents (n = 77) and self-expandable plastic stents (SEPS) (n = 70) were inserted in 232 patients with refractory benign esophageal strictures. The overall clinical success rate was 24.2% and according to stent type 14.1% for FC SEMS, 32.9% for BD stents and 27.1% for SEPS. Stent migration occurred in 24.6% of cases. The overall complication rate was 31.0%, including major (17.7%) and minor (13.4%) complications. A total of 643 patients were treated with self-expandable stents mainly for postsurgical leaks (64.5%), iatrogenic perforations (19.6%), Boerhaave’s syndrome (7.8%) and fistulae (3.7%). FC SEMS and partially covered SEMS were used in the majority of patients. Successful closure of the defect was achieved in 76.8% of patients and according to etiology in 81.4% for postsurgical leaks, 86.0% for perforations and 64.7% for fistulae. The pooled stent migration rate was 16.5%. Stent-related complications occurred in 13.4% of patients, including major (7.8%) and minor (5.5%) complications. CONCLUSION: The outcomes of stent placement for refractory benign esophageal strictures were poor. However, randomized trials are needed to put this into perspective. The evidence on successful stent placement for benign

  4. 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.

  5. Carotid Artery Stenting Using a Novel Self-Expanding Braided Nickel-Titanium Stent: Feasibility and Safety Porcine Trial

    SciTech Connect

    Ahlhelm, Frank Kaufmann, Ralf; Ahlhelm, Dirk Ong, Mai Fang; Roth, Christian Reith, Wolfgang

    2009-09-15

    We studied the deliverability and safety of a braided, self-expanding, closed-cell nickel-titanium (NiTi) stent (E-volution, Jotec GmbH, Hechingen, Germany) especially designed for the endovascular treatment of carotid artery bifurcation stenosis with special regard to in-stent stenosis and thrombosis compared with a laser-cut reference nitinol stent in a porcine model of percutaneous vascular interventions. We aimed to assess histopathologic response in minipig carotid and subclavian arteries. Eight minipigs received a total of 42 stents: 14 reference stents and 28 E-volution stents. Eleven of the E-volution stents were additionally coated with heparin. Control angiography was obtained immediately before and after vascular intervention as well as 4 weeks after the procedure. Primary endpoints were 28 days of angiographic analyses as well as histomorphometric analysis, including injury score, inflammation score, luminal diameter, vessel diameter, maximal neointimal thickness, and area of in-stent stenosis. Secondary end points were procedural success, 28-day mortality, and stent thrombosis. All stents could be delivered successfully without procedural complications, morbidity, or mortality during our observation time. As confirmed by histology, no in-stent thrombosis was observed. Compared with common carotid arteries, subclavian arteries are significantly more vulnerable to developing in-stent stenosis caused by neointima proliferation (p < 0.05). Compared with the use of 1 single stent/artery, serial application of two stents leads to a more excessive but not significantly different neointimal proliferation (p > 0.05). The E-volution stent, especially when heparin coated, is in line with the comparison to the laser-cut reference stent displaying similar results of angiographic, histologic, and histomorphometric analyses (p > 0.05). Compared with the reference laser-cut stent, the self-expanding nitinol stent (E-volution) with its advanced braiding technology is

  6. 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.

  7. Trimming a Metallic Biliary Stent Using an Argon Plasma Coagulator

    SciTech Connect

    Rerknimitr, Rungsun Naprasert, Pisit; Kongkam, Pradermchai; Kullavanijaya, Pinit

    2007-06-15

    Background. Distal migration is one of the common complications after insertion of a covered metallic stent. Stent repositioning or removal is not always possible in every patient. Therefore, trimming using an argon plasma coagulator (APC) may be a good alternative method to solve this problem. Methods. Metallic stent trimming by APC was performed in 2 patients with biliary Wallstent migration and in another patient with esophageal Ultraflex stent migration. The power setting was 60-100 watts with an argon flow of 0.8 l/min. Observations. The procedure was successfully performed and all distal parts of the stents were removed. No significant collateral damage to the nearby mucosa was observed. Conclusions. In a patient with a distally migrated metallic stent, trimming of the stent is possible by means of an APC. This new method may be applicable to other sites of metallic stent migration.

  8. Metallic stents in malignant biliary obstruction

    SciTech Connect

    Rieber, Andrea; Brambs, Hans-Juergen

    1997-01-15

    Purpose. Retrospective analysis of our results with metallic stent placement for malignant biliary strictures. We sought to determine parameters that influence stent patency. Methods. A total of 95 Wallstents were implanted in 65 patients (38 men, 27 women; mean age, 65.1 years) with malignant biliary obstruction. Serum bilirubin levels were assessed in 48 patients; the mean value prior to intervention was 15.0 mg/dl. Results. In 12 patients (21%) complications occurred as a result of percutaneous transhepatic drainage. Stent implantation was complicated in 13 patients, but was possible in all patients. A significant decrease in bilirubin level was seen in 83.3% of patients following stent implantation. Approximately 30% of patients developed recurrent jaundice after a mean 97.1 days. In 9 patients (15%) the recurrent jaundice was caused by stent occlusion due to tumor growth. The mean follow-up was 141.8 days, the mean survival 118.7 days. Patients with cholangiocarcinomas and gallbladder carcinomas had the best results. Worse results were seen in patients with pancreatic tumors and with lymph node metastases of colon and gastric cancers. Conclusions. The main predictive factors for occlusion rate and survival are the type of primary tumor, tumor stage, the decrease in bilirubin level, and the general condition of the patient.

  9. 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.

  10. 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.

  11. 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.

  12. A two-center comparative study of plastic and lumen-apposing large diameter self-expandable metallic stents in endoscopic ultrasound-guided drainage of pancreatic fluid collections

    PubMed Central

    Ang, Tiing Leong; Kongkam, Pradermchai; Kwek, Andrew Boon Eu; Orkoonsawat, Piyachai; Rerknimitr, Rungsun; Fock, Kwong Ming

    2016-01-01

    Background and Objectives: Endoscopic ultrasound-guided drainage of walled-off pancreatic fluid collections (PFCs) (pseudocyst [PC]; walled-off necrosis [WON]) utilizes double pigtail plastic stents (PS) and the newer large diameter fully covered self-expandable stents (FCSEMS) customized for PFC drainage. This study examined the impact of type of stent on clinical outcomes and costs. Patients and Methods: Retrospective two-center study. Outcome variables were technical and clinical success, need for repeat procedures, need for direct endoscopic necrosectomy (DEN), and procedure-related costs. Results: A total of 49 (PC: 31, WON: 18) patients were analyzed. Initially, PS was used in 37 and FCSEMS in 12. Repeat transmural drainage was required in 14 (PS: 13 [9 treated with PS, 4 treated with FCSEMS]; FCSEMS: 1 [treated with PS]) due to stent migration (PS: 3; FCSEMS: 1) or inadequate drainage (PS: 10). Technical success was 100%. Initial clinical success was 64.9% (25/38) for PS versus 91.7% (11/12) for FCSEMS (P = 0.074). With repeat transmural stenting, final clinical success was achieved in 94.6% and 100%, respectively (P = 0.411). Compared to FCSEMS, PS was associated with greater need for repeat drainage (34.2% vs. 6.3%, P = 0.032). The need for and frequency of DEN was similar between both groups, but PS required more frequent balloon dilatation. PS was significantly cheaper for noninfected PC. Costs were similar for infected PC and WON. Conclusion: PS was associated with a higher need for a second drainage procedure to achieve clinical success. The use of FCSEMS did not increase procedural costs for infected PC and WON. PMID:27803905

  13. Initial Experience with the Resonance Metallic Stent for Antegrade Ureteric Stenting

    SciTech Connect

    Wah, Tze M. Irving, Henry C.; Cartledge, Jon

    2007-07-15

    Background and purpose. We describe our initial experience with a new metallic ureteric stent which has been designed to provide long-term urinary drainage in patients with malignant ureteric strictures. The aim is to achieve longer primary patency rates than conventional polyurethane ureteric stents, where encrustation and compression by malignant masses limit primary patency. The Resonance metallic double-pigtail ureteric stent (Cook, Ireland) is constructed from coiled wire spirals of a corrosion-resistant alloy designed to minimize tissue in-growth and resist encrustation, and the manufacturer recommends interval stent change at 12 months. Methods. Seventeen Resonance stents were inserted via an antegrade approach into 15 patients between December 2004 and March 2006. The causes of ureteric obstruction were malignancies of the bladder (n = 4), colon (n = 3), gynecologic (n = 5), and others (n = 3). Results. One patient had the stent changed after 12 months, and 3 patients had their stents changed at 6 months. These stents were draining adequately with minimal encrustation. Four patients are still alive with functioning stents in situ for 2-10 months. Seven patients died with functioning stents in place (follow-up periods of 1 week to 8 months). Three stents failed from the outset due to bulky pelvic malignancy resulting in high intravesical pressure, as occurs with conventional plastic stents. Conclusion. Our initial experience with the Resonance metallic ureteric stent indicates that it may provide adequate long-term urinary drainage (up to 12 months) in patients with malignant ureteric obstruction but without significantly bulky pelvic disease. This obviates the need for regular stent changes and would offer significant benefit for these patients with limited life expectancy.

  14. Metallic stent in the endoscopic treatment of pancreatic fluid collections

    PubMed Central

    Tozlu, M.; Kocaman, O.; Baysal, B.; Ince, A.; Danalioglu, A.; Kayar, Y.; Senturk, H.

    2014-01-01

    Background and Aims: The endoscopic treatment of pancreatic fluid collections (PFCs) has become the preferred first-line approach. Fully covered self-expandable metal stents (FCSEMS) were considered as an alternative to multiple double pigtail stents. The aim of this study was to evaluate the results of the endosonography guided drainage (EUS-GD) of PFCs with FCEMS. Materials and Methods: A total of 33 consecutive patients were included. Cystogastrostomy and cystoduodenostomy were created with a linear echoendoscope under endosonographic and fluoroscopic control. Procedures were performed in a standard way of, puncture with a 19 gauge needle, bougie dilation and insertion of FCSEMS. Results: A total of 33 patients (mean age 52 years, 21 men, range: 18-77 years), were included. PFCs were 22 non-infected symptomatic pseudocyst and 11 walled-off necrosis or abscess. EUS-GD was successful in 30 (90.9%) patients. Stent insertion failed in one patient. Two patients needed surgery. Complications were observed in 8 (25%) patients (stent dislocation in 3, perforation in 2, bleeding in 2 and pneumoperitoneum in 1 patient). Procedure related mortality was not seen. The mean cyst size was 11.3 cm (5-22). FCSEMS were successful in the treatment of pseudocysts (after 1 month mean cyst size is 6.2 cm, range: 0-15 cm, with 54.8% decrement rate). During a mean follow-up of 15 months complete resolution was 66.6% (20 patients) and recurrence due to stent malfunction was 10%. All these cases were submitted to a new session of endoscopic drainage. Conclusions: EUS-GD, FCSEMS insertion provides an effective, minimally invasive, and safe approach in the management of PFCs. PMID:26425505

  15. 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.

  16. In-situ investigation of stress conditions during expansion of bare metal stents and PLLA-coated stents using the XRD sin(2)ψ-technique.

    PubMed

    Kowalski, Wolfgang; Dammer, Markus; Bakczewitz, Frank; Schmitz, Klaus-Peter; Grabow, Niels; Kessler, Olaf

    2015-09-01

    Drug eluting stents (DES) consist of platform, coating and drug. The platform often is a balloon-expandable bare metal stent made of the CoCr alloy L-605 or stainless steel 316 L. The function of the coating, typically a permanent polymer, is to hold and release the drug, which should improve therapeutic outcome. Before implantation, DES are compressed (crimped) to allow implantation in the human body. During implantation, DES are expanded by balloon inflation. Crimping, as well as expansion, causes high stresses and high strains locally in the DES struts, as well as in the polymer coating. These stresses and strains are important design criteria of DES. Usually, they are calculated numerically by finite element analysis (FEA), but experimental results for validation are hardly available. In this work, the X-ray diffraction (XRD) sin(2)ψ-technique is applied to in-situ determination of stress conditions of bare metal L-605 stents, and Poly-(L-lactide) (PLLA) coated stents. This provides a realistic characterization of the near-surface stress state and a validation option of the numerical FEA. XRD-results from terminal stent struts of the bare metal stent show an increasing compressive load stress in tangential direction with increasing stent expansion. These findings correlate with numerical FEA results. The PLLA-coating also bears increasing compressive load stress during expansion.

  17. Shape optimization of stress concentration-free lattice for self-expandable Nitinol stent-grafts.

    PubMed

    Masoumi Khalil Abad, Ehsan; Pasini, Damiano; Cecere, Renzo

    2012-04-01

    In a mechanical component, stress-concentration is one of the factors contributing to reduce fatigue life. This paper presents a design methodology based on shape optimization to improve the fatigue safety factor and increase the radial stiffness of Nitinol self-expandable stent-grafts. A planar lattice free of stress concentrators is proposed for the synthesis of a stent with smooth cell shapes. Design optimization is systematically applied to minimize the curvature and reduce the bending strain of the elements defining the lattice cells. A novel cell geometry with improved fatigue life and radial supportive force is introduced for Nitinol self-expandable stent-grafts used for treating abdominal aortic aneurism. A parametric study comparing the optimized stent-graft to recent stent designs demonstrates that the former exhibits a superior anchoring performance and a reduction of the risk of fatigue failure. PMID:22304844

  18. 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

  19. 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.

  20. 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.

  1. Polyurethane-Covered Self-expandable Nitinol Stent for Malignant Biliary Obstruction: Preliminary Results

    SciTech Connect

    Han, Young-Min; Hwang, Seung-Bae; Lee, Soo-Teik; Lee, Jeong-Min; Chung, Gyung-Ho

    2002-10-15

    Purpose: To evaluate the immediate and long-term results in ten patients with malignant biliary obstruction using a polyurethane-covered, self-expandable nitinol stent.Methods: A nitinol stent, fully covered with high-elasticity polyurethane, with an unconstrained diameter of 10 mm and a total length of 60-80 mm, was placed transhepatically under fluoroscopic guidance in ten patients. The length of the biliary obstruction varied between 30-50 mm. The follow-up examination included a clinical assessment, serum bilirubin measurement, and ultrasound examinations at one-month intervals in all patients. Results: Initial stent deployment was successful in eight patients. Two patients experienced proximal migration,which was solved by insertion of two, uncovered Wallstents. One patient had the stent removed after two weeks because of severe nausea and vomiting. One patient had delayed migration of the covered stent after 40 weeks. The follow-up duration was 3-40 weeks (Mean: 16.9 weeks). Seven patients died(3-26 weeks) and three patients survived (24-40 weeks). The bilirubin measurements in all patients had significantly decreased one week after stent insertion. The levels of amylase and lipase had did not increase after stent insertion. Conclusions: Apolyurethane-covered, self-expandable nitinol stent can be used effectively and safely in the treatment of malignant biliary obstruction. The preliminary results are favorable, but there is a need for further large studies to determine both long-term survival and patency.

  2. Mechanisms of Biliary Plastic Stent Occlusion and Efforts at Prevention

    PubMed Central

    Kwon, Chang-Il; Lehman, Glen A.

    2016-01-01

    Biliary stenting via endoscopic retrograde cholangiopancreatography has greatly improved the quality of patient care over the last 30 years. Plastic stent occlusion limits the life span of such stents. Attempts to improve plastic stent patency duration have mostly failed. Metal stents (self-expandable metal stents [SEMSs]) have therefore replaced plastic stents, especially for malignant biliary strictures. SEMS are at least 10 times more expensive than plastic stents. In this focused review, we will discuss basic mechanisms of plastic stent occlusion, along with a systematic summary of previous efforts and related studies to improve stent patency and potential new techniques to overcome existing limitations. PMID:27000422

  3. 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.

  4. Crush implantation of a self-expanding interwoven stent over a subintimally recanalized standard stent in a TASC D lesion of the superficial femoral artery.

    PubMed

    Vogel, B; Strothmeyer, A; Cebola, R; Katus, H; Blessing, E

    2012-11-01

    We demonstrate feasibility of implantation of a self-expanding interwoven nitinol stent in a claudicant, where recanalization attempt of a heavily calcified, occluded superficial femoral artery (TASC D lesion) was complicated by a previously implanted, fractured standard stent. Wire passage through the occlusion and beyond the fractured stent could only be achieved through the subintimal space. A dedicated reentry device was used to allow distal wire entry into the true lumen at the level of the popliteal artery. Despite crushing of the fractured stent with a series of increasingly sized standard balloons, a significant recoil remainded in the area of the crushed stent. To secure patency of the femoro-popliteal artery we therefore decided to implant the novel self-expanding interwoven nitinol stent (Supera Veritas (TM), IDEV), whose unique feature is an exceptional high radial strength. Patient presented asymptomatic without any impairment of his walking capacity at three month follow up and duplex ultrasound confirmed patency of the stent. Subintimal recanalizations can be complicated by previously implanted stents, in particular in the presence of stent fracture, where intraluminal wire passage often can not be achieved. Considering the high radial strength and fracture resistance, interwoven nitinol stents represent a good treatment option in those challenging cases and they can be used to crush standard nitinol and ballonexpandable stents. PMID:23129042

  5. Impact of stent strut design in metallic stents and biodegradable scaffolds.

    PubMed

    Foin, Nicolas; Lee, Renick D; Torii, Ryo; Guitierrez-Chico, Juan Luis; Mattesini, Alessio; Nijjer, Sukhjinder; Sen, Sayan; Petraco, Ricardo; Davies, Justin E; Di Mario, Carlo; Joner, Michael; Virmani, Renu; Wong, Philip

    2014-12-20

    Advances in the understanding of healing mechanisms after stent implantation have led to the recognition of stent strut thickness as an essential factor affecting re-endothelialization and overall long term vessel healing response after Percutaneous Coronary Interventions (PCI). Emergence of Drug-eluting stents (DESs) with anti-proliferative coating has contributed to reducing the incidence of restenosis and Target Lesion Revascularization (TVR), while progress and innovations in stent materials have in the meantime facilitated the design of newer platforms with more conformability and thinner struts, producing lesser injury and improving integration into the vessel wall. Recent advances in biodegradable metal and polymer materials now also allow for the design of fully biodegradable platforms, which are aimed at scaffolding the vessel only temporarily to prevent recoil and constrictive remodeling of the vessel during the initial period required, and are then progressively resorbed thereby avoiding the drawback of leaving an unnecessary implant permanently in the vessel. The aim of this article is to review recent evolution in stent material and stent strut design while understanding their impact on PCI outcomes. The article describes the different metallic alloys and biodegradable material properties and how these have impacted the evolution of stent strut thickness and ultimately outcomes in patients.

  6. Treatment of anastomotic leaks with metallic stent after esophagectomies.

    PubMed

    Eizaguirre, E; Larburu, S; Asensio, J I; Rodriguez, A; Elorza, J L; Loyola, F; Urdapilleta, G; Navascués, J M E

    2016-01-01

    The diagnosis and the treatment of anastomotic leak after esophagectomy are the keys to reduce the morbidity and mortality after this surgery. The stent plays an important role in the treatment of the leakage and in the prevention of reoperation. We have analyzed the database of the section of the esophagogastric surgery of Donostia University Hospital from June 2003 to May 2012. It is a retrospective study of 113 patients with esophagectomy resulting from tumor, and 24 (21.13%) of these patients developed anastomotic leak. Of these 24 patients, 13 (54.16%) have been treated with a metallic stent and 11 (45.84%) without a stent. The average age of the patients was 55.69 and 62.45 years, respectively. All patients treated with and without a stent have been males. Eight (61.5%) stents were placed in the neck and five (38.5%) in the chest. However, among the 11 fistulas treated without a stent, 9 patients had cervical anastomosis (81.81%) and 2 patients (18.18%) had anastomosis in the chest. Twelve patients (92.30%) with a stent preserve digestive continuity, and 10 patients (90.90%) were treated without a stent. One patient died in the stent group and one in the nonstent group. The treatment with metallic stent of the anastomotic leak after esophagectomy is an option that can prevent reoperation in these patients, but it does not decrease the average of the hospital stay. The stent may be more useful in thoracic anastomotic leaks.

  7. Results of the self-expandable BA9 stent for treatment of large angle coronary bifurcation.

    PubMed

    Lucisano, L; Calcagno, S; Pennacchi, M; Stio, R E; Mancone, M; Sardella, G

    2014-02-01

    Since the advent of coronary angioplasty the treatment of bifurcation lesions has always proved a complex issue resulting in lower angiographic success rates, increased risk of restenosis, higher rates of dissection, myocardial infarction, and acute vessel closure. The advent of coronary stenting reduced the risks, but in-stent restenosis was noted to be frequent at the ostium of the side branch; for this reasons two-stent techniques were developed to try to combat this phenomenon. Novel dedicated stents have recently been developed to provide easier access to the SB and to scaffold more effectively its ostium, matching the stent configuration more closely to the anatomy of the bifurcation. Most of bifurcation lesions that require treatment and which have a wide angle involving the left main coronary artery (LMCA). The impact of the angle and the asymmetry of bifurcation on flow dynamic are very important and may influence clinical outcome. More recently, percutaneous coronary intervention (PCI) to treat wide angle disease has increased in frequency, and is associated with improvements in interventional techniques and adjunctive drug therapy. Several studies have shown that stenting in LMCA, especially using drug-eluting stents (DES), is a safe and effective treatment strategy both at mid- and long-term follow-up. The AXXESS System is a self-expanding, conically-shaped stent from nitinol (nickel-titanium alloy) with strut thickness, specifically designed to conform to the anatomy at the level of the bifurcation carina. A special version of the AXXESS System has been designed for left main bifurcation lesions, allowing for larger diameters (up to 4.75 mm) and distinct bifurcation angles (flare-end diameters of 8, 10 and 12 mm). The AXXENT trial is the first study to evaluate the vascular response of the self-expanding biolimus-eluting AXXESS stent for the treatment of LMCA bifurcation lesions. It was designed to evaluate the safety and efficacy of the AXXESS

  8. 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.

  9. Deployment of self-expandable stents in aneurysmatic cerebral vessels: comparison of different computational approaches for interventional planning.

    PubMed

    Bernardini, A; Larrabide, I; Petrini, L; Pennati, G; Flore, E; Kim, M; Frangi, A F

    2012-01-01

    In the last few years, there has been a growing focus on faster computational methods to support clinicians in planning stenting procedures. This study investigates the possibility of introducing computational approximations in modelling stent deployment in aneurysmatic cerebral vessels to achieve simulations compatible with the constraints of real clinical workflows. The release of a self-expandable stent in a simplified aneurysmatic vessel was modelled in four different initial positions. Six progressively simplified modelling approaches (based on Finite Element method and Fast Virtual Stenting--FVS) have been used. Comparing accuracy of the results, the final configuration of the stent is more affected by neglecting mechanical properties of materials (FVS) than by adopting 1D instead of 3D stent models. Nevertheless, the differences showed are acceptable compared to those achieved by considering different stent initial positions. Regarding computational costs, simulations involving 1D stent features are the only ones feasible in clinical context.

  10. Fully Covered Metallic Stents for the Treatment of Benign Airway Stenosis

    PubMed Central

    Ocak, Sebahat; Gourdin, Maximilien; d'Odémont, Jean-Paul

    2016-01-01

    Introduction. We herein report our experience with new fully covered self-expanding metallic stents in the setting of inoperable recurrent benign tracheobronchial stenosis. Methods. Between May 2010 and July 2014, 21 Micro-Tech® FC-SEMS (Nanjing Co., Republic of Korea) were placed in our hospital in 16 patients for inoperable, recurrent (after dilatation), and symptomatic benign airway stenosis. Their medical files were retrospectively reviewed in December 2014, with focus on stent's tolerance and durability data. Results. Twenty-one stents were inserted: 13 for posttransplant left main bronchus anastomotic stricture, seven for postintubation tracheal stenosis, and one for postlobectomy anastomotic stricture. Positioning was easy for all of them. Stents were in place for a mean duration of 282 days. The most common complications were granulation tissue development (35%), migration (30%), and sputum retention (15%). Fifty-five % of the stents (11/20) had to be removed because of various complications, without difficulty for all of them. None of the patients had life-threatening complications. Conclusion. Micro-Tech FC-SEMS were easy to position and to remove. While the rate of complications requiring stent removal was significant, no life-threatening complication occurred. Further studies are needed to better define their efficacy and safety in the treatment of benign airway disease. PMID:27777507

  11. Modeling smooth muscle cell proliferation of coronary artery expanded with a drug eluting stent

    NASA Astrophysics Data System (ADS)

    Lyu, Suping

    2010-03-01

    The drug eluting coronary stent is for the treatment of narrowed coronary artery. A high strength balloon is used to open the narrowed vessel and leave behind a tiny metal mesh, or stent, to mechanically prevent the vessel from re-narrowing and biologically slow down proliferation of the smooth muscle cells. However, the drug eluting stents that had better performance also more seriously prevented the healing processes of the vessels, which could cause serious thrombotic reactions. In this study, we assume the healing process is controlled by proper proliferation of smooth cells. We also assume that the inflammation reactions and mechanical traction drive the smooth muscle cells to proliferate while the drug loaded in the stents drives the processes at the opposite direction. Numerical calculation was applied to the system. The drug distribution and elution durations, inflammation reactions and mechanical traction were discussed.

  12. 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.

  13. 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.

  14. 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

  15. Self-Expanding Nitinol Renal Artery Stents: Comparison of Safety and Efficacy of Bare Versus Polyzene-F Nanocoated Stents in a Porcine Model

    SciTech Connect

    Kurz, P.; Stampfl, U.; Christoph, P.; Henn, C.; Satzl, S.; Radeleff, B.; Berger, I.; Richter, G. M.

    2011-02-15

    Objective: To investigate the safety and efficacy of a Polyzene-F nanocoat on new low-profile self-expandable nitinol stents in minipig renal arteries. Materials and Methods: Ten bare nitinol stents (BNS) and 10 stents coated with a 50 nm-thin Polyzene-F coating were randomly implanted into renal arteries of 10 minipigs (4- and 12-week follow-up, 5 animals/group). Thrombogenicity, on-stent surface endothelialization, vessel wall injury, late in-stent stenosis, and peristrut vessel wall inflammation were determined by quantitative angiography and postmortem histomorphometry. Results: In 6 of 10 BNS, >50% stenosis was found, but no stenosis was found in stents with a nanothin Polyzene-F coating. Histomorphometry showed a statistically significant (p < 0.05) different average maximum luminal loss of 55.16% {+-} 8.43% at 12 weeks in BNS versus 39.77% {+-} 7.41% in stents with a nanothin Polyzene-F coating. Stents with a nanothin Polyzene-F coating had a significantly (p < 0.05) lower inflammation score after 12 weeks, 1.31 {+-} 1.17 versus 2.17 {+-} 0.85 in BNS. The results for vessel wall injury (0.6 {+-} 0.58 for Polyzene-F-coated stents; 0.72 {+-} 0.98 for BNS) and re-endothelialization, (1.16 {+-} 0.43 and 1.23 {+-} 0.54, respectively) were not statistically significant at 12-week follow-up. No thrombus deposition was observed on the stents at either follow-up time point. Conclusion: Nitinol stents with a nanothin Polyzene-F coating successfully decreased in-stent stenosis and vessel wall inflammation compared with BNS. Endothelialization and vessel wall injury were found to be equal. These studies warrant long-term pig studies ({>=}120 days) because 12 weeks may not be sufficient time for complete healing; thereafter, human studies may be warranted.

  16. 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

  17. A Double-Layered Covered Biliary Metal Stent for the Management of Unresectable Malignant Biliary Obstruction: A Multicenter Feasibility Study

    PubMed Central

    Park, Jin-Seok; Jeong, Seok; Lee, Don Haeng; Moon, Jong Ho; Lee, Kyu Taek; Dong, Seok Ho

    2016-01-01

    Background/Aims The covered self-expandable metal stent (CMS) was developed to prevent tumor ingrowth-induced stent occlusion during the treatment of malignant biliary obstruction. However, complications such as cholecystitis, pancreatitis, and stent migration can occur after the endoscopic insertion of CMSs. The aim of the present study was to assess the efficacy and safety of a double-layered CMS (DCMS) for the management of malignant bile duct obstruction. Methods DCMSs were endoscopically introduced into 59 patients with unresectable malignant extrahepatic biliary obstruction at four tertiary referral centers, and the patient medical records were retrospectively reviewed. Results Both the technical and functional success rates were 100%. Procedure-related complications including pancreatitis, cholangitis, stent migration, and liver abscess occurred in five patients (8.5%). The median follow-up period was 265 days (range, 31 to 752 days). Cumulative stent patency rates were 68.2% and 40.8% at 6 and 12 months, respectively. At the final follow-up, the rate of stent occlusion was 33.9% (20/59), and the median stent patency period was 276 days (range, 2 to 706 days). Conclusions The clinical outcomes of DCMSs were comparable to the outcomes previously reported for CMSs with respect to stent patency period and complication rates. PMID:27172927

  18. Endoscopic management of unresectable malignant gastroduodenal obstruction with a nitinol uncovered metal stent: A prospective Japanese multicenter study

    PubMed Central

    Sasaki, Reina; Sakai, Yuji; Tsuyuguchi, Toshio; Nishikawa, Takao; Fujimoto, Tatsuya; Mikami, Shigeru; Sugiyama, Harutoshi; Yokosuka, Osamu

    2016-01-01

    AIM: To determine the safety and efficacy of endoscopic duodenal stent placement in patients with malignant gastric outlet obstruction. METHODS: This prospective, observational, multicenter study included 39 consecutive patients with malignant gastric outlet obstruction. All patients underwent endoscopic placement of a nitinol, uncovered, self-expandable metal stent. The primary outcome was clinical success at 2 wk after stent placement that was defined as improvement in the Gastric Outlet Obstruction Scoring System score relative to the baseline. RESULTS: Technical success was achieved in all duodenal stent procedures. Procedure-related complications occurred in 4 patients (10.3%) in the form of mild pneumonitis. No other morbidities or mortalities were observed. The clinical success rate was 92.3%. The mean survival period after stent placement was 103 d. The mean period of stent patency was 149 d and the patency remained acceptable for the survival period. Stent dysfunction occurred in 3 patients (7.7%) on account of tumor growth. CONCLUSION: Endoscopic management using duodenal stents for patients with incurable malignant gastric outlet obstruction is safe and improved patients’ quality of life. PMID:27076769

  19. 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.

  20. Preprocedural Albumin Levels and Risk of In-Stent Restenosis After Coronary Stenting With Bare-Metal Stent.

    PubMed

    Celik, Ibrahim Etem; Yarlioglues, Mikail; Kurtul, Alparslan; Duran, Mustafa; Koseoglu, Cemal; Oksuz, Fatih; Aksoy, Ozlem; Murat, Sani Namik

    2016-05-01

    In-stent restenosis (ISR) remains a significant clinical problem in patients with coronary artery disease treated with percutaneous coronary intervention. Decreased serum albumin (SA) level is related to an increased risk of cardiovascular events. The aim of the present study was to assess whether SA levels at admission are an independent predictor of ISR in patients undergoing bare-metal stent (BMS) implantation. A total of 341 patients (aged 61 ± 11, 65.4% men) with a history of BMS implantation and a further control coronary angiography due to stable angina pectoris (SAP) were included. The study population was classified into 2 groups: patients with and without ISR. The ISR was observed in 140 (41.1%) patients. We found significantly lower SA levels in patients who developed ISR than in those who did not (3.69 ± 0.41 vs 4.07 ± 0.35 mg/dL,P< .001). Multivariate analysis revealed that SA level (odds ratio 0.109, 95% confidence interval 0.017-0.700,P= .020), stent diameter, reason for stent implantation, and body mass index were independent risk factors for the development of ISR. The SA level at admission is inversely associated with ISR in patients with SAP.

  1. 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.

  2. Primary Self-Expandable Nitinol Stent Placement in Focal Lesions of Infrarenal Abdominal Aorta: Long Term Results

    SciTech Connect

    Lastovickova, Jarmila Peregrin, Jan H.

    2008-01-15

    Purpose. To evaluate the technical and clinical success, safety and long term results of percutaneous transluminal angioplasty/self-expandable nitinol stent placement of infrarenal abdominal aorta focal lesions. Materials and Methods. Eighteen patients underwent PTA of focal atherosclerotic occlusive disease of distal abdominal aorta. Two symptomatic occlusions and 16 stenoses in 10 male and 8 female patients (mean age 68.2 years) were treated with primary self-expandable nitinol stent placement. Results. Primary self-expandable nitinol stent placement was technically successful in all 18 procedures; clinical success was achieved in 100% of patients. No complications associated with the procedure occurred. During the 49.4 months of mean follow up (range 3-96, 4 months) all treated aortic segments remained patent. Conclusions. Endovascular treatment (primary self-expandable nitinol stent placement) of focal atherosclerotic lesions of distal abdominal aorta is a safe method with excellent primary technical and clinical success rates and favourable Long term results.

  3. 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.

  4. 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

  5. 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.

  6. Use of Self-Expanding Stents for the Treatment of Vertebral Artery Ostial Stenosis: a Single Center Experience

    PubMed Central

    Chung, Sun Young; Choi, Jin Woo; Choi, Byung Se; In, Hyun Sin; Kim, Sun Mi; Choi, Choong Gon; Kim, Sang Joon; Suh, Dae Chul

    2010-01-01

    Objective To evaluate our early experience using self-expanding stents to treat atherosclerotic vertebral artery ostial stenosis (VAOS), with respect to technical feasibility and clinical and imaging follow-up results. Materials and Methods A total of 20 lesions in 20 patients underwent stenting of the VAOS using a self-expanding stent (Precise RX; Cordis Neurovascular, Miami Lakes, FL). Two patients were asymptomatic. We analyzed the technical success rate, causes of technical failure, occurrence of any vascular or neurological event, and the occurrence of any neurological abnormality or in-stent restenosis (ISR) seen on follow-up. The imaging follow-up was performed with Doppler ultrasound (DUS) as a primary screening modality. Results One instance of technical failure was caused by failure of the guidewire passage. The stent diameter was 5 mm, and post-stenting balloon dilatations were necessary in all cases. Stent misplacement requiring placement of an additional stent occurred in four cases. Following a 14.8 month average clinical follow-up time, two patients showed anterior circulation ischemia, which was not attributed to the VAOS we treated. Following a 13.7 month average DUS follow-up, five patients showed a mild degree of diffuse or focal intimal thickening in the stent lumen; however, none of the stenosis showed luminal loss of more than 50% and no stent fracture was noted. Conclusion The use of self-expanding stents for treating VAOS was technically feasible and helped to improve artery patency during our limited follow-up interval. PMID:20191062

  7. Stent selection in patients with myocardial infarction: drug eluting, biodegradable polymers or bare metal stents?

    PubMed

    Mieres, Juan; Rodríguez, Alfredo E

    2012-08-01

    Percutaneous coronary intervention (PCI) has been increasingly used in the last years during interventional procedures in patients with acute coronary syndromes (ACS) including ST elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI). In patients with either STEMI, NSTEMI, high risk ACS with EKG changes or cardiac enzymes rises; PCI with bare metal stent (BMS) implantation has been associated with a significant improvement in clinical outcome. Therefore, BMS implantation during primary PCI in STEMI has become a standard of practice. With the introduction of drug eluting stents (DESs) in this decade, the use of these new devices instead of BMSs in patients with STEMI has emerged as a rational PCI alternative in this particular subgroup of patients. In spite of the unquestionable benefits of DESs in terms of reduction of restenosis and TVR, specific concerns have arisen with regard to their long-term safety. High incidence of very late stent thrombosis has been described with these devices, and special attention should be paid in patients with unstable coronary lesions, in which plaque composition and remodeling may play a main role in their safety and long-term outcome. Intraluminal thrombus caused by plaque rupture is the most frequent mechanism of STEMI, in which the necrotic core and thin fibrous cap play a major role. In this context, the use of first DESs designs may be futile or even unsafe because delayed healing may further contribute to plaque instability. Adjunctive invasive imaging tools can improve stent deployment and safety outcome in these lesions with intravascular findings of plaque instability. Recently, other players such as new dedicated antithrombotic BMS designs, including selfexpanding stents or drug-eluting coated balloons, are exploring their potential indications in patients with ACS and myocardial infarction. This paper reports and discusses new stent devices and adjunctive pharmacologic agents. It

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

    PubMed

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

    2015-06-28

    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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Stent thrombosis in real-world patients: a comparison of drug-eluting with bare metal stents

    PubMed Central

    de Man, F.H.; Stella, P.R.; Nathoe, H.; Kirkels, H.; Hamer, B.; Meijburg, H.W.; Doevendans, P.A.

    2007-01-01

    Background Although the introduction of drugeluting stents (DES) has been associated with an impressive reduction in target vessel revascularisation, there has been concern about the safety profile. The aim of this study was to determine the incidence of stent thrombosis in real-world patients and evaluate the contribution of drug-eluting stents. Methods A prospective observational cohort study was conducted at a high-volume centre in Utrecht, the Netherlands. All patients who underwent a percutaneous coronary intervention (PCI) between 1 January and 31 December 2005 were evaluated. The patients were pretreated with aspirin and clopidogrel, which was continued for six months in bare metal stents (BMS) and 12 months in DES. Results In 2005, 1309 patients underwent a percutaneous coronary intervention procedure with stent implantation. After a median follow-up of nine months, 1.8% (n=23) of the patients had suffered from stent thrombosis. Two cases could be attributed to incorrect use of antiplatelet agents. In 8/23 cases, a technical reason was found such as an unrecognised dissection or stent underexpansion. The timing of stent thrombosis was acute in 1/23 patients, subacute in 20/23 patients and late in 2/23 patients. In both cases of late stent thrombosis, a BMS had been used. There were no differences in stent thrombosis rates between DES and BMS (1.4 vs. 1.9%, ns.). This is remarkable since DES were used in more complex and longer lesions. Conclusion The use of DES in routine daily practice does not appear to be associated with a higher rate of stent thrombosis than BMS. (Neth Heart J 2007;15:382-6.18176640Neth Heart J 2007;15:382-6). PMID:18176640

  16. Mechanical properties of different airway stents.

    PubMed

    Ratnovsky, Anat; Regev, Noa; Wald, Shaily; Kramer, Mordechai; Naftali, Sara

    2015-04-01

    Airway stents improve pulmonary function and quality of life in patients suffering from airway obstruction. The aim of this study was to compare main types of stents (silicone, balloon-dilated metal, self-expanding metal, and covered self-expanding metal) in terms of their mechanical properties and the radial forces they exert on the trachea. Mechanical measurements were carried out using a force gauge and specially designed adaptors fabricated in our lab. Numerical simulations were performed for eight different stent geometries, inserted into trachea models. The results show a clear correlation between stent diameter (oversizing) and the levels of stress it exerts on the trachea. Compared with uncovered metal stents, metal stents that are covered with less stiff material exert significantly less stress on the trachea while still maintaining strong contact with it. The use of such stents may reduce formation of mucosa necrosis and fistulas while still preventing stent migration. Silicone stents produce the lowest levels of stress, which may be due to weak contact between the stent and the trachea and can explain their propensity for migration. Unexpectedly, stents made of the same materials exerted different stresses due to differences in their structure. Stenosis significantly increases stress levels in all stents.

  17. 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. PMID:25590491

  18. 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

  19. 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.

  20. Clinical utility of platinum chromium bare-metal stents in coronary heart disease

    PubMed Central

    Jorge, Claudia; Dubois, Christophe

    2015-01-01

    Coronary stents represent a key development for the treatment of obstructive coronary artery disease since the introduction of percutaneous coronary intervention. While drug-eluting stents gained wide acceptance in contemporary percutaneous coronary intervention practice, further developments in bare-metal stents remain crucial for patients who are not candidates for drug-eluting stents, or to improve metallic platforms for drug elution. Initially, stent platforms used biologically inert stainless steel, restricting stent performance due to limitations in flexibility and strut thickness. Later, cobalt chromium stent alloys outperformed steel as the material of choice for stents, allowing latest generation stents to be designed with significantly thinner struts, while maintaining corrosion resistance and radial strength. Most recently, the introduction of the platinum chromium alloy refined stent architecture with thin struts, high radial strength, conformability, and improved radiopacity. This review will provide an overview of the novel platinum chromium bare-metal stent platforms available for coronary intervention. Mechanical properties, clinical utility, and device limitations will be summarized and put into perspective. PMID:26345228

  1. Clinical utility of platinum chromium bare-metal stents in coronary heart disease.

    PubMed

    Jorge, Claudia; Dubois, Christophe

    2015-01-01

    Coronary stents represent a key development for the treatment of obstructive coronary artery disease since the introduction of percutaneous coronary intervention. While drug-eluting stents gained wide acceptance in contemporary percutaneous coronary intervention practice, further developments in bare-metal stents remain crucial for patients who are not candidates for drug-eluting stents, or to improve metallic platforms for drug elution. Initially, stent platforms used biologically inert stainless steel, restricting stent performance due to limitations in flexibility and strut thickness. Later, cobalt chromium stent alloys outperformed steel as the material of choice for stents, allowing latest generation stents to be designed with significantly thinner struts, while maintaining corrosion resistance and radial strength. Most recently, the introduction of the platinum chromium alloy refined stent architecture with thin struts, high radial strength, conformability, and improved radiopacity. This review will provide an overview of the novel platinum chromium bare-metal stent platforms available for coronary intervention. Mechanical properties, clinical utility, and device limitations will be summarized and put into perspective. PMID:26345228

  2. Metallic Zinc Exhibits Optimal Biocompatibility for Bioabsorbable Endovascular Stents

    PubMed Central

    Bowen, Patrick K.; Guillory, Roger J.; Shearier, Emily R.; Seitz, Jan-Marten; Drelich, Jaroslaw; Bocks, Martin; Zhao, Feng; Goldman, Jeremy

    2015-01-01

    Although corrosion resistant bare metal stents are considered generally effective, their permanent presence in a diseased artery is an increasingly recognized limitation due to the potential for long-term complications. We previously reported that metallic zinc exhibited an ideal biocorrosion rate within murine aortas, thus raising the possibility of zinc as a candidate base material for endovascular stenting applications. This study was undertaken to further assess the arterial biocompatibility of metallic zinc. Metallic zinc wires were punctured and advanced into the rat abdominal aorta lumen for up to 6.5 months. This study demonstrated that metallic zinc did not provoke responses that often contribute to restenosis. Low cell densities and neointimal tissue thickness, along with tissue regeneration within the corroding implant, point to optimal biocompatibility of corroding zinc. Furthermore, the lack of progression in neointimal tissue thickness over 6.5 months or the presence of smooth muscle cells near the zinc implant suggest that the products of zinc corrosion may suppress the activities of inflammatory and smooth muscle cells. PMID:26249616

  3. Metallic zinc exhibits optimal biocompatibility for bioabsorbable endovascular stents.

    PubMed

    Bowen, Patrick K; Guillory, Roger J; Shearier, Emily R; Seitz, Jan-Marten; Drelich, Jaroslaw; Bocks, Martin; Zhao, Feng; Goldman, Jeremy

    2015-11-01

    Although corrosion resistant bare metal stents are considered generally effective, their permanent presence in a diseased artery is an increasingly recognized limitation due to the potential for long-term complications. We previously reported that metallic zinc exhibited an ideal biocorrosion rate within murine aortas, thus raising the possibility of zinc as a candidate base material for endovascular stenting applications. This study was undertaken to further assess the arterial biocompatibility of metallic zinc. Metallic zinc wires were punctured and advanced into the rat abdominal aorta lumen for up to 6.5months. This study demonstrated that metallic zinc did not provoke responses that often contribute to restenosis. Low cell densities and neointimal tissue thickness, along with tissue regeneration within the corroding implant, point to optimal biocompatibility of corroding zinc. Furthermore, the lack of progression in neointimal tissue thickness over 6.5months or the presence of smooth muscle cells near the zinc implant suggest that the products of zinc corrosion may suppress the activities of inflammatory and smooth muscle cells.

  4. A Novel Method for Insertion of the Straight Metallic Tracheal Stent.

    PubMed

    Prasad, Kuruswamy Thurai; Ram, Babu; Sehgal, Inderpaul Singh; Dhooria, Sahajal; Agarwal, Ritesh

    2016-10-01

    A straight metallic tracheal stent can be inserted either during flexible or rigid bronchoscopy. However, in patients with significant airway obstruction or those requiring tumor debulking, rigid bronchoscopy is the method of choice. A tracheoscope size 12 or larger is generally required for the introduction of the straight metallic tracheal stent. Herein, we describe a novel method that facilitates the introduction of the straight metallic tracheal stent through a size 8.5 tracheoscope by using the introducer tube of the silicone stent applicator. PMID:27645990

  5. Mechanisms and Patterns of Intravascular Ultrasound In-Stent Restenosis Among Bare Metal Stents and First- and Second-Generation Drug-Eluting Stents.

    PubMed

    Goto, Kosaku; Zhao, Zhijing; Matsumura, Mitsuaki; Dohi, Tomotaka; Kobayashi, Nobuaki; Kirtane, Ajay J; Rabbani, LeRoy E; Collins, Michael B; Parikh, Manish A; Kodali, Susheel K; Leon, Martin B; Moses, Jeffrey W; Mintz, Gary S; Maehara, Akiko

    2015-11-01

    The most common causes of in-stent restenosis (ISR) are intimal hyperplasia and stent under expansion. The purpose of this study was to use intravascular ultrasound (IVUS) to compare the ISR mechanisms of bare metal stents (BMS), first-generation drug-eluting stents (DES), and second-generation DES. There were 298 ISR lesions including 52 BMS, 73 sirolimus-eluting stents, 52 paclitaxel-eluting stents, 16 zotarolimus-eluting stents, and 105 everolimus-eluting stent. Mean patient age was 66.6 ± 1.1 years, 74.2% were men, and 48.3% had diabetes mellitus. BMS restenosis presented later (70.0 ± 66.7 months) with more intimal hyperplasia compared with DES (BMS 58.6 ± 15.5%, first-generation DES 52.6 ± 20.9%, second-generation DES 48.2 ± 22.2%, p = 0.02). Although reference lumen areas were similar in BMS and first- and second-generation DES, restenotic DES were longer (BMS 21.8 ± 13.5 mm, first-generation DES 29.4 ± 16.1 mm, second-generation DES 32.1 ± 18.7 mm, p = 0.003), and stent areas were smaller (BMS 7.2 ± 2.4 mm(2), first-generation DES 6.1 ± 2.1 mm(2), second-generation DES 5.7 ± 2.0 mm(2), p <0.001). Stent fracture was seen only in DES (first-generation DES 7 [5.0%], second-generation DES 8 [7.4%], p = 0.13). In conclusion, restenotic first- and second-generation DES were characterized by less neointimal hyperplasia, smaller stent areas, longer stent lengths, and more stent fractures than restenotic BMS.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. Drug-Eluting or Bare-Metal Stents for Coronary Artery Disease.

    PubMed

    Bønaa, Kaare H; Mannsverk, Jan; Wiseth, Rune; Aaberge, Lars; Myreng, Yngvar; Nygård, Ottar; Nilsen, Dennis W; Kløw, Nils-Einar; Uchto, Michael; Trovik, Thor; Bendz, Bjørn; Stavnes, Sindre; Bjørnerheim, Reidar; Larsen, Alf-Inge; Slette, Morten; Steigen, Terje; Jakobsen, Ole J; Bleie, Øyvind; Fossum, Eigil; Hanssen, Tove A; Dahl-Eriksen, Øystein; Njølstad, Inger; Rasmussen, Knut; Wilsgaard, Tom; Nordrehaug, Jan E

    2016-09-29

    Background Limited data are available on the long-term effects of contemporary drug-eluting stents versus contemporary bare-metal stents on rates of death, myocardial infarction, repeat revascularization, and stent thrombosis and on quality of life. Methods We randomly assigned 9013 patients who had stable or unstable coronary artery disease to undergo percutaneous coronary intervention (PCI) with the implantation of either contemporary drug-eluting stents or bare-metal stents. In the group receiving drug-eluting stents, 96% of the patients received either everolimus- or zotarolimus-eluting stents. The primary outcome was a composite of death from any cause and nonfatal spontaneous myocardial infarction after a median of 5 years of follow-up. Secondary outcomes included repeat revascularization, stent thrombosis, and quality of life. Results At 6 years, the rates of the primary outcome were 16.6% in the group receiving drug-eluting stents and 17.1% in the group receiving bare-metal stents (hazard ratio, 0.98; 95% confidence interval [CI], 0.88 to 1.09; P=0.66). There were no significant between-group differences in the components of the primary outcome. The 6-year rates of any repeat revascularization were 16.5% in the group receiving drug-eluting stents and 19.8% in the group receiving bare-metal stents (hazard ratio, 0.76; 95% CI, 0.69 to 0.85; P<0.001); the rates of definite stent thrombosis were 0.8% and 1.2%, respectively (P=0.0498). Quality-of-life measures did not differ significantly between the two groups. Conclusions In patients undergoing PCI, there were no significant differences between those receiving drug-eluting stents and those receiving bare-metal stents in the composite outcome of death from any cause and nonfatal spontaneous myocardial infarction. Rates of repeat revascularization were lower in the group receiving drug-eluting stents. (Funded by the Norwegian Research Council and others; NORSTENT ClinicalTrials.gov number, NCT00811772 .).

  12. Development of a polymer stent with shape memory effect as a drug delivery system.

    PubMed

    Wache, H M; Tartakowska, D J; Hentrich, A; Wagner, M H

    2003-02-01

    The article presents a new concept for vascular endoprothesis (stent). Almost all commercially available stents are made of metallic materials. A common after effect of stent implantation is restenosis. Several studies on metal stents coated with drug show, that the use of a drug delivery system may reduce restenosis. The purpose of this work is to develop a new stent for the drug delivery application. The shape memory properties of thermoplastic polyurethane allow to design a new fully polymeric self-expandable stent. The possibility to use the stent as a drug delivery system is described.

  13. 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

  14. 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

  15. 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

  16. [Our experience with the use of a plastic prosthesis and self-expanding stents in the palliative treatment of malignant neoplastic stenoses of the esophagus and cardia. Comparative analysis of results].

    PubMed

    Mosca, Francesco; Consoli, Antonino; Stracqualursi, Antonio; Persi, Achille; Lipari, Giuseppe; Portale, Teresa Rosanna

    2002-01-01

    Rapid palliation of malignant dysphagia is usually possible by means of the endoscopic implantation of a plastic prosthesis, but this device has a high morbidity rate. Recently, expandable metal stents have become available and may reduce the morbidity and mortality rates. The aim of this retrospective study was to evaluate self-expanding metal stents compared with conventional plastic prosthesis in malignant strictures of the oesophagus and cardia. One hundred and thirteen endoscopic tube implantations were carried out in 120 patients with malignant stenosis of the oesophagus and cardia using a plastic prosthesis over the period 1980-1993 (72 cases) and self-expanding metal stents over the period 1993-2001 (48 cases). The underlying causes of strictures were oesophageal or cardial cancer in 108 cases and oesophageal invasion by lung cancer in 12. The indications for endoscopic intubation were advanced tumour stage and/or risk factors which made resection inadvisable. The stents used in the conventional group were the Celestin pulsion tube in 18, the Atkinson prosthesis in 23 and the Wilson-Cook tube in 27, while the Ultraflex stent was always employed in the other group. Dysphagia was scored according to the Atkinson and Ferguson classification and the preoperative median score (3.6) was comparable in the two groups. The technical success rate was 94.4% with the plastic prosthesis (68/72) and 93.7% with the self-expanding metal stents (45/48) because in 4 and 3 patients, respectively, it proved impossible to implant the stent. After intubation the dysphagia score was improved in both groups (median score = 0.9) and the functional success rates were 85.2% (58/68) and 88.8% (40/45), respectively, while 10 and 5 patients showed no improvement of symptoms. The early complication rate was 5.9% (4/68) in the conventional stent group (1 perforation, 2 severe bleedings and 1 stent proximal migration) and nil in the other group. Late complications occurred in 14 (20.6%) (7

  17. [Our experience with the use of a plastic prosthesis and self-expanding stents in the palliative treatment of malignant neoplastic stenoses of the esophagus and cardia. Comparative analysis of results].

    PubMed

    Mosca, Francesco; Consoli, Antonino; Stracqualursi, Antonio; Persi, Achille; Lipari, Giuseppe; Portale, Teresa Rosanna

    2002-01-01

    Rapid palliation of malignant dysphagia is usually possible by means of the endoscopic implantation of a plastic prosthesis, but this device has a high morbidity rate. Recently, expandable metal stents have become available and may reduce the morbidity and mortality rates. The aim of this retrospective study was to evaluate self-expanding metal stents compared with conventional plastic prosthesis in malignant strictures of the oesophagus and cardia. One hundred and thirteen endoscopic tube implantations were carried out in 120 patients with malignant stenosis of the oesophagus and cardia using a plastic prosthesis over the period 1980-1993 (72 cases) and self-expanding metal stents over the period 1993-2001 (48 cases). The underlying causes of strictures were oesophageal or cardial cancer in 108 cases and oesophageal invasion by lung cancer in 12. The indications for endoscopic intubation were advanced tumour stage and/or risk factors which made resection inadvisable. The stents used in the conventional group were the Celestin pulsion tube in 18, the Atkinson prosthesis in 23 and the Wilson-Cook tube in 27, while the Ultraflex stent was always employed in the other group. Dysphagia was scored according to the Atkinson and Ferguson classification and the preoperative median score (3.6) was comparable in the two groups. The technical success rate was 94.4% with the plastic prosthesis (68/72) and 93.7% with the self-expanding metal stents (45/48) because in 4 and 3 patients, respectively, it proved impossible to implant the stent. After intubation the dysphagia score was improved in both groups (median score = 0.9) and the functional success rates were 85.2% (58/68) and 88.8% (40/45), respectively, while 10 and 5 patients showed no improvement of symptoms. The early complication rate was 5.9% (4/68) in the conventional stent group (1 perforation, 2 severe bleedings and 1 stent proximal migration) and nil in the other group. Late complications occurred in 14 (20.6%) (7

  18. Comparison of neointimal morphology of in-stent restenosis with sirolimus-eluting stents versus bare metal stents: virtual histology-intravascular ultrasound analysis.

    PubMed

    Yamamoto, Yoshihiro; Otani, Hajime; Iwasaka, Junji; Park, Haengnam; Sakuma, Takao; Kamihata, Hiroshi; Iwasaka, Toshiji

    2011-09-01

    Sirolimus-eluting stents (SES) have reduced the incidence of restenosis and target lesion revascularization compared to bare metal stents (BMS). However, inhibition of endothelialization and neointimal formation after SES implantation may produce vulnerable plaques. The present study compared the neointimal morphology of in-stent restenosis (ISR) between SES and BMS using virtual histology-intravascular ultrasound (VH-IVUS). Thirty ISR lesions (SES n = 15, BMS n = 15) demonstrated by coronary angiography in 30 patients with stable angina pectoris were analyzed with VH-IVUS between 6 months to 3 years after stent implantation. Tissue maps were reconstructed from radiofrequency data using VH-IVUS software. ISR lesions after SES implantation consisted of a significantly increased necrotic core (NC) compared to BMS (12.9 vs. 5.6% of neointimal volume, p < 0.01). However, the NC in ISR lesions after SES implantation was covered with a thick fibrous cap. An increase in the size of NC covered with a thick fibrous cap is a characteristic morphological feature of ISR after SES implantation. Further studies are needed to clarify whether such a morphological change is related to the attenuation of stent thrombosis after SES implantation.

  19. 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.

  20. Chronic vascular response after self-expanding nitinol stent implantation in superficial femoral arteries: a serial intravascular ultrasound analysis.

    PubMed

    Nishimura, Machiko; Fujii, Kenichi; Fukunaga, Masashi; Kawasaki, Daizo; Miki, Kojiro; Saita, Ten; Horimatsu, Tetsuo; Tamaru, Hiroto; Imanaka, Takahiro; Naito, Yoshiro; Masuyama, Tohru

    2016-10-01

    The mechanical properties of the self-expanding nitinol stents (SENS) and chronic biological stimulation on the wall from the SENS have not been fully investigated. This study evaluated the mechanical vascular response to SENS implantation in superficial femoral artery (SFA) lesions using serial volumetric intravascular ultrasound (IVUS). Twenty-five symptomatic patients due to de novo SFA lesions scheduled for SENS placement were prospectively enrolled. Serial IVUS studies were performed immediately after crossing with a guidewire, immediately after the procedure, and at a 8-month follow-up. Serial IVUS volumetric analysis was conducted after stent deployment and at follow-up. Mean stent, lumen and neointimal areas were calculated as the volume divided by the stent length, and the calcium arc was measured. At follow-up, SENS had increased 40.6 % in overall volume. The chronic stent expansion tended to be larger, and the mean neointimal area at the 8-month follow-up was significantly larger in less calcified lesions compared to heavily calcified lesions. As a result, the mean late lumen area loss was significantly larger in lesions with calcium arcs of 0° and in the first and second quadrants than in those with calcium arcs in the third and fourth quadrants (2.8 ± 7.2, 1.3 ± 5.6, 0.6 ± 5.9, 1.2 ± 5.4, -0.8 ± 5.2 mm(2), respectively; p < 0.001). SENSs continued to enlarge with intimal proliferation over 8 months in all lesions. Although arterial calcium affected the degree of chronic stent expansion during the follow-up period, neointimal proliferation was smaller in heavily calcified lesion compared to less calcified lesion following SENS implantation.

  1. Common bile duct perforation sealed with a metal fully-covered stent.

    PubMed

    García-Cano, Jesús; Ferri-Bataller, Ramón; Gómez-Ruiz, Carmen Julia

    2016-08-01

    A common bile duct perforation due to sphincteroplasty is reported. It was managed by temporary insertion of a metal fully covered stent with good outcomes. Images from the procedure are provided. PMID:27554382

  2. Self expandable stent application to prevent limb occlusion in external iliac artery during endovascular aneurysm repair

    PubMed Central

    Lee, Jae Hoon

    2016-01-01

    Purpose Iliac extension of stent-graft during endovascular aneurysm repair (EVAR) increases the incidence of limb occlusion (LO). Hypothetically, adjunctive iliac stent (AIS) could offer some additional protection to overcome this anatomic hostility. But still there is no consensus in terms of effective stent characteristics or configuration. We retrospectively reviewed our center's experience to offer a possible answer to this question. Methods Our study included 30 patients (38 limbs) with AIS placed in the external iliac artery (EIA) from January 2010 to December 2013. We classified iliac tortuosity based on anatomic characteristics. AIS's were deployed in EIA with a minimum 5-mm stick-out configuration from the distal edge of the stent-graft. Results According to the iliac artery tortuosity index, grade 0, grade 1, and grade 2 were 5 (13.2%), 30 (78.9%), and 3 (7.9%), respectively. The diameter of all AIS was 12 mm, which was as large as or larger than the diameter of the stent-graft distal limb. SMART stents were preferred in 34 limbs (89.5%) and stents with 60-mm length were usually used (89.5%). During a mean follow-up of 9.13 ± 10.78 months, ischemic limb pain, which could be the sign of LO, was not noticed in any patients. There was no fracture, kinking, migration, in-stent restenosis, or occlusion of AIS. Conclusion The installation of AIS after extension of stent-graft to EIA reduced the risk of LO without any complications. AIS should be considered as a preventive procedure of LO if stent-graft needs to be extended to EIA during EVAR.

  3. Self expandable stent application to prevent limb occlusion in external iliac artery during endovascular aneurysm repair

    PubMed Central

    Lee, Jae Hoon

    2016-01-01

    Purpose Iliac extension of stent-graft during endovascular aneurysm repair (EVAR) increases the incidence of limb occlusion (LO). Hypothetically, adjunctive iliac stent (AIS) could offer some additional protection to overcome this anatomic hostility. But still there is no consensus in terms of effective stent characteristics or configuration. We retrospectively reviewed our center's experience to offer a possible answer to this question. Methods Our study included 30 patients (38 limbs) with AIS placed in the external iliac artery (EIA) from January 2010 to December 2013. We classified iliac tortuosity based on anatomic characteristics. AIS's were deployed in EIA with a minimum 5-mm stick-out configuration from the distal edge of the stent-graft. Results According to the iliac artery tortuosity index, grade 0, grade 1, and grade 2 were 5 (13.2%), 30 (78.9%), and 3 (7.9%), respectively. The diameter of all AIS was 12 mm, which was as large as or larger than the diameter of the stent-graft distal limb. SMART stents were preferred in 34 limbs (89.5%) and stents with 60-mm length were usually used (89.5%). During a mean follow-up of 9.13 ± 10.78 months, ischemic limb pain, which could be the sign of LO, was not noticed in any patients. There was no fracture, kinking, migration, in-stent restenosis, or occlusion of AIS. Conclusion The installation of AIS after extension of stent-graft to EIA reduced the risk of LO without any complications. AIS should be considered as a preventive procedure of LO if stent-graft needs to be extended to EIA during EVAR. PMID:27617255

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

    PubMed

    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

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

    PubMed

    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.

  6. Repeat Procedures Within 30 days in Patients Stented for Malignant Distal Biliary Strictures: Experience of 508 Patients at a Tertiary Referral Center

    PubMed Central

    Byrne, Michael F; Chan, Calvin HY; Branch, Malcolm S; Jowell, Paul S; Baillie, John

    2012-01-01

    Background Stent related occlusion and migration remains a problem despite attempts to improve stent design over this time period. Flanged polyethylene plastic stents (FPS) remains the stent of choice in most centers. Early failure of stents placed for malignant extrahepatic biliary strictures (MEBS) has not previously been studied in detail. We set out to determine the incidence and reasons for biliary stent change within 30 days of the index procedure in a large tertiary center population during a period where (FPS) was the sole plastic stent used. Methods Retrospective analysis of endoscopic retrograde cholangiography (ERCP) was undertaken in patients who were stented for presumed or known MEBS between 1993 and 2001. Patients who required repeat stenting within 30 days were identified. Results All 508 patients were stented for MEBS. 5.7% of patients had a total of 34 repeat stenting procedures within 30 days of the index procedure; 27of 29 index stents were plastic, 2 were self-expandable metal stents (SEMS), 20 (3.9%) patients had stent failure as the reason for a stent exchange (plastic stent occlusion n = 15, mean time to stent change 14 ± 8.3 days; metal stent occlusion n = 2, mean time to stent change 24.5 ± 7.8 days; plastic stent migration n = 3, mean time to stent change 25 ± 5.3 days). There was a statistically significant difference in the time to stent change between the occluded plastic stent and migrated plastic stent cases (P = 0.045, 95% CI -21.7 to -0.29). 6 patients spent at least 2 additional days in hospital as a result of stent failure. Conclusions Early stent failure is an uncommon problem, especially in patients with SEMS. Early plastic stent failure appears to occur sooner with stent occlusion than with stent migration. Early stent failure is associated with significant morbidity and bears an economic impact in additional procedures and hospital stay.

  7. 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 %.

  8. Improved vascular healing after the successful treatment of very late sirolimus-eluting stent thrombosis with a bare metal stent implantation - A serial optical coherence tomography study.

    PubMed

    Bouki, Konstantina P; Vlad, Delia; Riga, Maria; Stergiouli, Ifigenia; Toutouzas, Konstantinos P

    2016-01-01

    We present the case of a patient with non-ST-elevated myocardial infarction due to very late stent thrombosis 2 years after a sirolimus-eluting stent implantation (SES). Optical coherence tomography (OCT) imaging identified vessel wall destruction of the whole stented coronary segment with multiple cavity formations along the entire stent length, severe strut malapposition and thrombi. The patient was treated successfully with the implantation of a bare metal stent (BMS). Follow-up OCT imaging at 12 months revealed the improvement of vascular healing with complete re-endothelialization of the distal parts of the new BMS, while the stent body remained partly uncovered, suggesting vascular toxicity due to the old SES. PMID:27445030

  9. An Efficient Finite Element Framework to Assess Flexibility Performances of SMA Self-Expandable Carotid Artery Stents

    PubMed Central

    Ferraro, Mauro; Auricchio, Ferdinando; Boatti, Elisa; Scalet, Giulia; Conti, Michele; Morganti, Simone; Reali, Alessandro

    2015-01-01

    Computer-based simulations are nowadays widely exploited for the prediction of the mechanical behavior of different biomedical devices. In this aspect, structural finite element analyses (FEA) are currently the preferred computational tool to evaluate the stent response under bending. This work aims at developing a computational framework based on linear and higher order FEA to evaluate the flexibility of self-expandable carotid artery stents. In particular, numerical simulations involving large deformations and inelastic shape memory alloy constitutive modeling are performed, and the results suggest that the employment of higher order FEA allows accurately representing the computational domain and getting a better approximation of the solution with a widely-reduced number of degrees of freedom with respect to linear FEA. Moreover, when buckling phenomena occur, higher order FEA presents a superior capability of reproducing the nonlinear local effects related to buckling phenomena. PMID:26184329

  10. 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.

  11. 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

  12. An overview on laser microfabrication of bicompatible metallic stent for medical therapy

    NASA Astrophysics Data System (ADS)

    Kathuria, Yash P.

    2004-04-01

    With the established technique of laser in precision micromaterial processing, the fabrication of cardiovascular metallic stent with high quality has now become feasible. From the actual CAD design and FEM analysis of the stent fabrication, the need for the surface modification properties becomes essential in enduring its extended life duration. This paper describes the current status as well as fabrication of such metallic stent of length 20 mm and dia. 2.1 mm with an annular tube thickness of 0.2 mm, by using the short pulse Nd-YAG laser. Fine structures with slit width of 0.1 mm and pitch better than 0.2 mm are created with sharpness and low roughness in the cut surface. Some features on improving the surface characteristics of the cut surfaces of the stent, excimer laser coronary angioplasty and ultrasound ablation of plaque as well as a few techniques on preventing restenosis are well documented.

  13. Long term impact of balloon post-dilatation on neointimal formation: an experimental comparative study between second-generation self-expanding versus balloon-expandable stent technologies.

    PubMed

    Aboodi, Michael S; Milewski, Krzysztof; Tellez, Armando; Cheng, Yanping; Yi, Geng-Hua; Kaluza, Greg L; Granada, Juan F

    2014-02-15

    Background: Self-expanding stents (SES) are reemerging as therapeutic alternatives to treat coronary artery disease. It has been proposed that SES can improve clinical outcomes by inducing less injury at implantation and achieving better vessel wall apposition.To date, little data exists comparing the vascular response to both methods of deployment in a controlled experimental setting. Objective: To quantify differences in vascular injury and healing between second-generation SES and balloon-expandable stents (BES) and the effects of balloon post-dilatation in a porcine coronary model. Methods: Seventy-five bare SES (AXXESS or vProtect) and 42 BES (Vision) were implanted in porcine coronaries. A subset of these received balloon post-dilatation(SES 1 D 5 22, BES 1 D 5 20). Follow-up was scheduled at 30 (BES 5 10, BES 1 D 56, SES 5 19, SES 1 D 5 8), 90 (BES 5 6, BES 1 D 5 8, SES 5 19, SES 1 D 5 8), and 180 days (BES 5 6, BES 1 D 5 6, SES 5 15, SES 1 D 5 6). Results: In vivo imaging and histological analysis showed that neointimal formation peaks early (30 days) in BES. Conversely, for SES, the peak occurred later (90 days). However, the neointimal formation achieved in either group equalized at 180 days. For SES, post-dilatation shortened the peak of neointimal formation to 30 days. Conversely, for BES, post-dilatation delayed the peak of neointimal formation to 90 days. At 30 days, histology showed that SES had significantly less injury. However, at 90 days, injury scores tended to be higher for SES. By 180 days, injury scores were comparable between both groups. Conclusions: The mechanism of stent expansion influences the degree of vascular injury and healing. The synergistic use of balloon post dilatation changes the dynamics of healing and may impact the potential beneficial effects inherent to SES technologies.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Balloon-Expandable Stent Placement in Patients with Immediate Reocclusion after Initial Successful Thrombolysis of Acute middle Cerebral Arterial Obstruction

    PubMed Central

    Lee, H.K.; Kwak, H.S.; Chung, G.H.; Hwang, S.B.

    2012-01-01

    Summary We present the results of our approach for treating 12 consecutive cases of acute middle cerebral artery (MCA) stroke by performing balloon-expandable stent (BES) placement after immediate reocclusion due to the underlying stenosis after intra-arterial thrombolysis (IAT). We retrospectively reviewed the clinical outcomes of 12 patients with acute MCA stroke who underwent recanalization by BES placement in an underlying stenosis after IAT. The time to treatment, urokinase dose, duration of the procedure, recanalization rates and symptomatic hemorrhage were analyzed. Clinical outcome measures were assessed on admission and at discharge (the National Institutes of Health stroke scores [NIHSS]) as well as three months after treatment (modified Rankin scales [mRS]). The median NIHSS score on admission was 8.6. Four patients received IV rtPA. The median time from symptom onset to IAT was 236 minutes and the median duration of IAT was 62 minutes. The median dose of urokinase was 140,000 units. Initial recanalization after stent deployment (thrombolysis in cerebral ischemia attack grade of II or III) was achieved in all patients. Two patients died in the hospital due to aspiration pneumonia during medical management. In two patients, in-stent reocclusion occurred within 48 hours after stent deployment. At discharge, the median NIHSS score in ten patients (including the patients with reobstruction) was 2.4. The three-month outcome was excellent (mRS, 0-1) in eight patients. In this study, BES deployment was safe and effective in patients with an immediately reoccluded MCA after successful IAT. PMID:22440605

  19. 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.

  20. 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.

  1. 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. PMID:26384666

  2. 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

  3. 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.

  4. 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.

  5. Use of the Viatorr Expanded Polytetrafluoroethylene-Covered Stent-Graft for Transjugular Intrahepatic Portosystemic Shunt Creation in Children: Initial Clinical Experience

    SciTech Connect

    Mermuys, Koen; Maleux, Geert Heye, Sam; Lombaerts, Rita; Nevens, Frederik

    2008-07-15

    Four children, three boys and one girl, with a median age of 9 years 8 months, underwent transjugular intrahepatic portosystemic shunt creation with an expanded polytetrafluoroethylene (e-PTFE)-covered nitinol stent. The stent-graft was successfully placed in all four patients without any complication. Clinical and biochemical improvement was noted in all four patients during follow-up. Radiological follow-up with use of duplex ultrasound showed a recurrent stenosis of the shunt 180 days after stent-graft implantation in one patient. This was treated with placement of an additional stent-graft, re-expanding completely the recurrent stenosis. In the other three patients, the stent-graft remained fully patent until the end of the study or until orthotopic liver transplantation. These preliminary results suggest that use of the Viatorr ePTFE-covered stent-graft in children is safe and feasible, with potentially the same high patency rate and improved clinical outcome as reported in adult patients.

  6. Serial insertion of bilateral uncovered metal stents for malignant hilar obstruction using an 8 Fr biliary system: a case series of 17 consecutive patients

    PubMed Central

    Thosani, Amar; Grunwald, Matthew; Nagula, Satish; Bucobo, Juan Carlos; Buscaglia, Jonathan M.

    2015-01-01

    Controversy exists over the need for unilateral versus bilateral stent placement in patients with malignant obstruction at the biliary hilum. Placement of bilateral uncovered self-expanding metal stent (UCSEMS) at this location is technically challenging, and generally associated with lower rates of procedural success. Serial insertion of side-by-side UCSEMS may be especially difficult when simultaneous deployment is not possible using larger stent delivery catheters. In this single-center, retrospective case series of all patients who underwent bilateral placement of uncovered WallflexTM biliary stents between July 2008 and July 2014, we evaluate the feasibility, technical success, and safety of patients undergoing serial insertion of bilateral UCSEMS using the 8 Fr WallflexTM biliary system for malignant hilar obstruction. A total of 17 patients were included. Primary cholangiocarcinoma, Bismuth IV, was the most common diagnosis. Mean procedure time was 54.4 minutes. Overall procedural technical success was achieved in 17/17 patients. Stricture dilation was necessary prior to WallflexTM insertion in 8/17 patients (47.1%). Transpapillary extension of two stents was performed in all patients. There were no cases of stent deployment malfunction, or inability to insert or deploy the 2nd stent. Nine of 17 patients (52.9%) required inpatient hospitalization following ERCP; the most common indications were abdominal pain and need for IV antibiotics. There was one case of ERCP-related cholangitis otherwise; there were no other major complications. Bilateral, serial insertion of UCSEMS using the 8 Fr WallflexTM biliary system in malignant hilar obstruction is feasible with an excellent technical success profile. Using this device for side-by-side deployment of UCSEMS appears to be safe in the majority of patients. PMID:26605283

  7. Metallic stent and flexible bronchoscopy without fluoroscopy for acute respiratory failure.

    PubMed

    Lin, S-M; Lin, T-Y; Chou, C-L; Chen, H-C; Liu, C-Y; Wang, C-H; Lin, H-C; Yu, C-T; Lee, K-Y; Kuo, H-P

    2008-05-01

    Stent implantation has been reported to facilitate liberation from mechanical ventilation in patients with respiratory failure due to central airway disease. The present retrospective cohort study sought to evaluate the risk and benefit of stent implantation via bronchoscopy without fluoroscopic guidance in mechanically ventilated patients. From July 2001 to September 2006, 26 patients with acute respiratory failure were recruited. A bronchoscope was inserted through a mouth guard into the space between the tracheal wall and the endotracheal tube. A guide wire was inserted via the flexible bronchoscope to the lesion site. The bronchoscope was reintroduced through the endotracheal tube. Under bronchoscopic visualisation, the delivery catheter was advanced over the guide wire to deploy the stent. These procedures were successfully performed in 26 patients, with 22 stents placed in the trachea and seven in the main bronchus. Of the 26 patients, 14 (53.8%) became ventilator independent during their stay in the intensive care unit. Severe pneumonia was the most common cause, in seven (58.3%) out of 12 patients, for continued ventilator dependence after stenting. Granulation tissue formation was found in seven patients during the follow-up period. It is concluded that metallic stents can be safely implanted without fluoroscopic guidance in patients with respiratory failure, to facilitate ventilator independence.

  8. Small Bowel Stent-in-Stent Placement for Malignant Small Bowel Obstruction Using a Balloon-Assisted Overtube Technique

    PubMed Central

    Popa, Daniel; Ramesh, Jayapal; Peter, Shajan; Wilcox, C. Mel

    2014-01-01

    Self-expanding metal stents are a useful therapy to palliate malignant and benign luminal gastrointestinal obstruction. Self-expanding metal stents has been widely reported for colonic, esophageal, and gastric obstruction. However, endoscopic delivery and placement to the small bowel is more challenging and difficult. This case illustrates the usefulness and technical advantages of the balloon-overtube and enteroscopy technique for the palliative treatment of neoplastic stenosis affecting the small intestine. PMID:24570892

  9. 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

  10. [Usefulness of Metallic Stent for Left-Sided Obstructive Colon Cancer].

    PubMed

    Shimizu, Yosuke; Tominaga, Harumi; Yamashita, Shinya; Kimura, Yuri; Odagiri, Kazuki; Kurokawa, Tomoaki; Yamaguchi, Megumi; Takahashi, Gen; Sawada, Genta; Inoue, Masashi; Jeongho, Moon; Irei, Toshimitsu; Nakahira, Shin; Hatanaka, Nobutaka

    2015-11-01

    The aim of this study was to compare the efficacy of self-expandable metallic stent (SEMS) and transanal tube as preoperative treatments for left-sided obstructive colon cancer. Forty-three patients (the SEMS group: 28 cases, the tube group: 15 cases) were included in this study. Clinicopathological data (age, sex, tumor location, depth, histological type, stage) were comparable between the 2 groups. In addition, there was no difference in intestinal decompression rate between the SEMS group and the tube group (technical success rate: 100% vs 86.7%, clinical success rate: 92.8% vs 73.3%, complication rate: 7.1% vs 0%). A significantly higher number of patients in the SEMS group underwent laparoscopic surgery because of difference of historical background. However, no significant difference was observed between the 2 groups in postoperative outcome(complication rate, hospital stay duration). SEMS insertion had several benefits compared to transanal tube placement, such as the resumption of oral intake because of rapid resolution of obstruction and easier management because SEMSs do not require washing. SEMS insertion could be a safe and effective bridge to subsequent surgery in patients with left-sided obstructive colon cancer. PMID:26805322

  11. 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.

  12. 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

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

    PubMed

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

    2016-08-10

    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

  14. Lethal post-endoscopic retrograde cholangiopancreatography pancreatitis following fully covered metal stent placement in distal biliary obstruction due to unresectable cholangiocarcinoma.

    PubMed

    Itoi, Takao; Tsuchiya, Takayoshi; Tanaka, Reina; Ikeuchi, Nobuhito; Sofuni, Atsushi

    2013-05-01

    Biliary self-expandable metallic stent (SEMS) is the preferred and first-line therapy for unresectable malignant biliary obstruction. To date, several reports have revealed the relatively high incidence of acute complications such as pancreatitis and cholecystitis due to mechanical stent compression. In the present case, we encountered fatal pancreatitis following fully covered metal stent placement. An 85-year-old man had middle bile duct strictures due to cholangiocarcinoma. A 10-mm diameter fully covered SEMS was placed across the papilla for biliary decompression. Laboratory data and physical evidence the following day revealed acute pancreatitis. Therefore, antibiotics and protein degeneration enzyme inhibitors were given. However, his condition did not improve. Two days after the procedure, we removed the stent and returned him to his original hospital. Serum amylase level decreased below 400 mg/dL 6 h after the procedure. However, the acute pancreatitis worsened. Although we treated the patient in the intensive care unit, he died 32 days after the second admission.

  15. 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. PMID:27158397

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. A Survival Analysis of Patients with Malignant Biliary Strictures Treated by Percutaneous Metallic Stenting

    SciTech Connect

    Brountzos, Elias N. Ptochis, Nikolaos; Panagiotou, Irene; Malagari, Katerina; Tzavara, Chara; Kelekis, Dimitrios

    2007-02-15

    Background. Percutaneous metal stenting is an accepted palliative treatment for malignant biliary obstruction. Nevertheless, factors predicting survival are not known. Methods. Seventy-six patients with inoperable malignant biliary obstruction were treated with percutaneous placement of metallic stents. Twenty patients had non-hilar lesions. Fifty-six patients had hilar lesions classified as Bismuth type I (n = 15 patients), type II (n = 26), type III (n = 12), or type IV (n = 3 patients). Technical and clinical success rates, complications, and long-term outcome were recorded. Clinical success rates, patency, and survival rates were compared in patients treated with complete (n = 41) versus partial (n = 35) liver parenchyma drainage. Survival was calculated and analyzed for potential predictors such as the tumor type, the extent of the disease, the level of obstruction, and the post-intervention bilirubin levels. Results. Stenting was technically successful in all patients (unilateral drainage in 70 patients, bilateral drainage in 6 patients) with an overall significant reduction of the post-intervention bilirubin levels (p < 0.001), resulting in a clinical success rate of 97.3%. Clinical success rates were similar in patients treated with whole-liver drainage versus partial liver drainage. Minor and major complications occurred in 8% and 15% of patients, respectively. Mean overall primary stent patency was 120 days, while the restenosis rate was 12%. Mean overall secondary stent patency was 242.2 days. Patency rates were similar in patients with complete versus partial liver drainage. Mean overall survival was 142.3 days. Survival was similar in the complete and partial drainage groups. The post-intervention serum bilirubin level was an independent predictor of survival (p < 0.001). A cut-off point in post-stenting bilirubin levels of 4 mg/dl dichotomized patients with good versus poor prognosis. Patient age and Bismuth IV lesions were also independent predictors

  2. The expanding indications for virtual histology intravascular ultrasound for plaque analysis prior to carotid stenting.

    PubMed

    Schiro, B J; Wholey, M H

    2008-12-01

    Complications of carotid artery stenting (CAS), including stroke, remain relatively high when compared with carotid endarterectomy (CEA). Current selection criteria for patients undergoing CAS are based predominately on surgical risk related to other comorbidities. Little attention is given to the morphology of the atherosclerotic plaque, although studies have shown that extensive variability exists which confers certain risks for plaque vulnerability. Virtual Histology intravascular ultrasound (VH IVUS) offers a unique method of assessing plaque morphology prior to CAS. Herein, the authors review the concepts of atherosclerotic plaque morphology and discuss the background of VH IVUS and illustrate its use in the carotid system. With selection of the appropriate patient and the appropriate plaque, more favorable outcomes of CAS may be achieved which will solidify its place as a frontline treatment of carotid vascular disease.

  3. 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

  4. 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

  5. The impact of material characteristics on the mechanical properties of a poly(L-lactide) coronary stent.

    PubMed

    Grabow, N; Martin, H; Schmitz, K P

    2002-01-01

    Biodegradable polymer stents as an alternative to metallic vascular stents have long been under discussion. However, for various reasons no such stent concept has been made available for commercial use until today. One reason may be, that still little is known about the mechanical properties of polymer stents and their dependency on the material characteristics. In this study, finite element analysis is used to investigate the mechanical properties of a balloon expandable PLLA stent under various load conditions. It is shown, how material parameters, such as elastic modulus, yield level and material hardening, influence stent recoil and collapse behavior. PMID:12451906

  6. 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.

  7. 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

  8. Late Migration of Covered Metal Stent to the Stomach Through a Spontaneous Choledochoduodenal Fistula in a Patient With Malignant Biliary Obstruction

    PubMed Central

    Katakura, Yoshiki; Asaki, Tsutoshi; Adachi, Seitaro; Yasuda, Ikuma; Toyomizu, Michifumi; Fukita, Yosho

    2012-01-01

    We report a case in which a spontaneous choledochoduodenal fistula occurred after biliary covered self-expanding metal stent (SEMS) placement and a late transfistula migration of the stent in a patient with malignant distal biliary obstruction. A partially covered WallFlex biliary stent (Boston Scientific) was appropriately implanted in the common bile duct. Subsequently the patient received chemotherapy with gemcitabine. After 7 months of the SEMS insertion, the patient presented with frequent vomiting. Abdominal computed tomography revealed the obstruction of the duodenal descending part and the migrated stent in the stomach. A choledochoduodenal fistula was observed endoscopically at the proximal point of the duodenal obstruction. These findings can cleanly account for the SEMS migration through the fistula. The mechanism of formation of the fistula is mostly associated with a mechanical contact between the bile duct wall and the SEMS edge, which is pushed up in the direction of the duodenum because of the enlargement of the primary tumor, finally penetrating through the duodenal wall. To our knowledge, this is an extreme unusual case, which has been unreported previously. Therefore, we emphasize the necessity of being alert to the potential for such complications in cases involving placement of SEMS for malignant biliary obstruction.

  9. Medical Devices; Gastroenterology-Urology Devices; Classification of the Metallic Biliary Stent System for Benign Strictures. Final order.

    PubMed

    2016-07-13

    The Food and Drug Administration (FDA) is classifying the metallic biliary stent system for benign strictures into class II (special controls). The special controls that will apply to the device are identified in this order and will be part of the codified language for the metallic biliary stent system for benign strictures' classification. The Agency is classifying the device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device. PMID:27411238

  10. Evaluation of IVOCT imaging of coronary artery metallic stents with neointimal coverage.

    PubMed

    Elahi, Sahar; Ho, Derek; Feldman, Marc D; Dijkstra, Jouke; Milner, Thomas E

    2015-03-01

    Accuracy of IVOCT for measurement of neointimal thickness and effect of neointima in the appearance of metallic struts in IVOCT images was investigated. Phantom vessels were constructed and coronary stents were deployed and covered with thick (250-400 μm) and thin (30-70 μm) phantom neointima. High resolution Micro-CT images of the stent struts were recorded as a gold standard. IVOCT images of the phantom vessels were acquired with various luminal blood scattering strengths and measured neointimal thicknesses from IVOCT and Micro-CT images were compared. In transparent lumen, comparison of IVOCT and Micro-CT neointima thickness measurements found no significant difference (p > 0.05) in the thick neointima phantom but a significant difference (p < 0.05) in the thin neointima phantom. For both thick and thin neointima, IVOCT neointimal thickness measurements varied from Micro-CT values by as much as ±35%. Increased luminal scattering due to presence of blood at concentrations <5% did not interfere with measurement of thin neointimas and was validated by ANOVA analysis (p = 0.95). IV-OCT measurement of strut feature size with an overlying thin neointima match true values determined with Micro-CT (p = 0.82). Presence of a thick neointima resulted in lateral elongation or merry-go-rounding of stent strut features in IVOCT images. Phantom IVOCT images suggest that thick neointimal layers can result in more than 40 % lateral elongation of stent strut features. Simulated IVOCT images of metallic stent struts with varying neointimal thickness suggest that neointimal light scattering can introduce the merry-go-round effect. PMID:25395364

  11. Evaluation of IVOCT imaging of coronary artery metallic stents with neointimal coverage.

    PubMed

    Elahi, Sahar; Ho, Derek; Feldman, Marc D; Dijkstra, Jouke; Milner, Thomas E

    2015-03-01

    Accuracy of IVOCT for measurement of neointimal thickness and effect of neointima in the appearance of metallic struts in IVOCT images was investigated. Phantom vessels were constructed and coronary stents were deployed and covered with thick (250-400 μm) and thin (30-70 μm) phantom neointima. High resolution Micro-CT images of the stent struts were recorded as a gold standard. IVOCT images of the phantom vessels were acquired with various luminal blood scattering strengths and measured neointimal thicknesses from IVOCT and Micro-CT images were compared. In transparent lumen, comparison of IVOCT and Micro-CT neointima thickness measurements found no significant difference (p > 0.05) in the thick neointima phantom but a significant difference (p < 0.05) in the thin neointima phantom. For both thick and thin neointima, IVOCT neointimal thickness measurements varied from Micro-CT values by as much as ±35%. Increased luminal scattering due to presence of blood at concentrations <5% did not interfere with measurement of thin neointimas and was validated by ANOVA analysis (p = 0.95). IV-OCT measurement of strut feature size with an overlying thin neointima match true values determined with Micro-CT (p = 0.82). Presence of a thick neointima resulted in lateral elongation or merry-go-rounding of stent strut features in IVOCT images. Phantom IVOCT images suggest that thick neointimal layers can result in more than 40 % lateral elongation of stent strut features. Simulated IVOCT images of metallic stent struts with varying neointimal thickness suggest that neointimal light scattering can introduce the merry-go-round effect.

  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. Rare and fatal complication of Gianturco tracheobronchial stent.

    PubMed

    Asopa, Sanjay; Moorjani, Narain; Saad, Rasheed A; Turner, Jonathan T; Amer, Khalid M

    2007-11-01

    Tracheobronchial stents are increasingly being used for the management of compromised large airways. Traditionally they have been used to palliate malignant conditions; however, they are now being used more frequently for nonmalignant conditions. The use of Gianturco self-expanding metal stent (William Cook, Bjaeverskov, Denmark) has been challenged for treatment of tracheobroncheomalacia, as fracture of the metal work could prove fatal. In this report we describe a case of fracture in the metal framework of a Gianturco stent resulting in recurrent pneumothoraces; heralding fatal haemoptysis as a result of perforation of the left subclavian artery.

  14. Internally folded expanded metal electrode for battery construction

    NASA Technical Reports Server (NTRS)

    Korinek, Paul D. (Inventor); Morgan, Maurice C. (Inventor); Pierce, Doug C. (Inventor)

    1993-01-01

    A battery system is disclosed which includes folded grids of expanded metal inserted through non-conductive substrates and pasted with electrochemically active materials. In the most preferred embodiment, a frame is provided with a plastic insert, and slots are provided in the latter to receive the expanded metal grid. After suitable coinage of the grid and insertion through the plastic film, the grid is sealed and pasted on opposite sides with positive and negative active material. A battery is assembled using one or a plurality of the resulting electrode elements, with separators, to produce a high-power, lead-acid battery. The folded grid provides many of the design benefits of standard bipolar construction.

  15. Endoscopic metal enteral stent placement for malignant afferent loop syndrome after pancreaticoduodenectomy

    PubMed Central

    Huang, Jiaxin; Hao, Sijie; Yang, Feng; Di, Yang; Yao, Lie; Li, Ji; Jiang, Yongjian; Zhong, Liang; Fu, Deliang

    2015-01-01

    Introduction Afferent loop syndrome (ALS) is a rare and dreaded complication after pancreaticoduodenectomy (PD). Malignant ALS after PD is usually difficult to manage due to patients’ poor condition. Effective and safe therapeutic strategies for these patients are reported scarcely at present. Aim To analyze and evaluate the clinical characteristics and treatment of these patients. Material and methods We analyzed 3 patients with malignant ALS after PD. They were treated by endoscopic enteral metal stent placement in our hospital. Meanwhile we retrospectively reviewed 49 cases with ALS after PD through available English literature. All these patients’ clinical features, laboratory study, treatment and outcome were evaluated. Results A total of 52 cases were analyzed in the study. The most common presenting symptoms of ALS after PD were jaundice (56.5%), upper abdominal pain (45.7%), fever (26.1%), and vomiting (23.9%). Sixty percent of ALS cases were caused by tumor recurrence. The mean time from prior surgery to diagnosis of ALS was 13.3 months. The rates of treatment with the endoscopic approach, percutaneous stenting or drainage, surgery, and the conservative method were 40.4%, 32.7%, 11.5%, and 15.4%, respectively. Endoscopic enteral metal stent placement proved more effective and less invasive in the treatment of malignant ALS after PD. Conclusions Cholangitis and cholangiectasis are the major manifestations of malignant ALS after PD. Invasive interventions are enjoying more and more acceptance for treatment. Endoscopic enteral metal stent placement appears to be a promising technique with effective palliation in these patients. PMID:26240626

  16. Carotid artery stenting: current and emerging options

    PubMed Central

    Morr, Simon; Lin, Ning; Siddiqui, Adnan H

    2014-01-01

    Carotid artery stenting technologies are rapidly evolving. Options for endovascular surgeons and interventionists who treat occlusive carotid disease continue to expand. We here present an update and overview of carotid stenting devices. Evidence supporting carotid stenting includes randomized controlled trials that compare endovascular stenting to open surgical endarterectomy. Carotid technologies addressed include the carotid stents themselves as well as adjunct neuroprotective devices. Aspects of stent technology include bare-metal versus covered stents, stent tapering, and free-cell area. Drug-eluting and cutting balloon indications are described. Embolization protection options and new direct carotid access strategies are reviewed. Adjunct technologies, such as intravascular ultrasound imaging and risk stratification algorithms, are discussed. Bare-metal and covered stents provide unique advantages and disadvantages. Stent tapering may allow for a more fitted contour to the caliber decrement between the common carotid and internal carotid arteries but also introduces new technical challenges. Studies regarding free-cell area are conflicting with respect to benefits and associated risk; clinical relevance of associated adverse effects associated with either type is unclear. Embolization protection strategies include distal filter protection and flow reversal. Though flow reversal was initially met with some skepticism, it has gained wider acceptance and may provide the advantage of not crossing the carotid lesion before protection is established. New direct carotid access techniques address difficult anatomy and incorporate sophisticated flow-reversal embolization protection techniques. Carotid stenting is a new and exciting field with rapidly advancing technologies. Embolization protection, low-risk deployment, and lesion assessment and stratification are active areas of research. Ample room remains for further innovations and developments. PMID:25349483

  17. Primary Patency of Wallstents in Malignant Bile Duct Obstruction: Single vs. Two or More Noncoaxial Stents

    SciTech Connect

    Maybody, Majid Brown, Karen T.; Brody, Lynn A.; Covey, Anne M.; Sofocleous, Constantinos T.; Thornton, Raymond H.; Getrajdman, George I.

    2009-07-15

    The purpose of this study was to determine the primary patency of two or more noncoaxial self-expanding metallic Wallstents (Boston Scientific, Natick, MA) and to compare this with the primary patency of a single stent in malignant bile duct obstruction. From August 2002 to August 2004, 127 patients had stents placed for malignant bile duct obstruction. Forty-five patients were treated with more than one noncoaxial self-expanding metallic stents and 82 patients had a single stent placed. Two patients in the multiple-stent group were lost to follow-up. The primary patency period was calculated from the date of stenting until the first poststenting intervention for stent occlusion, death, or the time of last documented follow-up. The patency of a single stent was significantly different from that of multiple stents (P = 0.0004). In the subset of patients with high bile duct obstruction, the patency of a single stent remained significantly different from that of multiple stents (P = 0.02). In the single-stent group, there was no difference in patency between patients with high vs. those with low bile duct obstruction (P = 0.43). The overall median patency for the multistent group and the single-stent group was 201 and 261 days, respectively. In conclusion, the patency of a single stent placed for malignant low or high bile duct obstruction is similar, and significantly longer than, that of multiple stents placed for malignant high bile duct obstruction. Given the median patency of 201 days, when indicated, percutaneous stenting of multiple bile ducts is an effective palliative measure for patients with malignant high bile duct obstruction.

  18. 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.

  19. 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.

  20. Fabrication and in vitro deployment of a laser-activated shape memory polymer vascular stent

    PubMed Central

    Baer, Géraldine M; Small, Ward; Wilson, Thomas S; Benett, William J; Matthews, Dennis L; Hartman, Jonathan; Maitland, Duncan J

    2007-01-01

    Background 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. Methods 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. Results 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 ~8 W. Conclusion 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. PMID:18042294

  1. Percutaneous transhepatic hybrid biliary endoprostheses using both plastic and metallic stents for palliative treatment of malignant common bile duct obstruction.

    PubMed

    Fujita, T; Tanabe, M; Takahashi, S; Iida, E; Matsunaga, N

    2013-11-01

    To evaluate clinical safety and efficacy of percutaneous transhepatic hybrid biliary prostheses for palliative treatment in patients with common bile duct obstruction caused by advanced malignancies. A total of 13 consecutive patients was treated with percutaneous transhepatic biliary endoprostheses concurrently using both plastic and metallic stents. Serum total bilirubin levels before and after stent placement were evaluated. The technical success rate, the period with no obstructive jaundice, patient survival and complications were also assessed. Median bilirubin levels decreased from 3.8 mg/dL before to 1.2 mg/dL after stent placement, and this difference was statistically significant. The median no-jaundice period after bile duct stent placement was 6.0 months (range: 2-11 months), and overall survival time was 7.0 months. Of the 13 patients, nine did not have recurrent jaundice by the time of death, whereas four (31%) had recurrent jaundice. A second intervention was performed in these four patients. A new plastic stent was placed and jaundice did not recur up to the time of death. No serious complications such as cholangitis, pancreatitis or bile duct perforation developed. Percutaneous transhepatic hybrid biliary endoprostheses using both plastic and metallic stents can be useful as non-invasive palliative treatment to relieve jaundice in patients with malignant obstructive jaundice.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Endoureteral Management of Renal Graft Ureteral Stenosis by the Use of Long-Term Metal Stent: An Appealing Treatment Option

    PubMed Central

    Treacy, Patrick-Julien; Rastinehad, Art R.; Imbert de la Phalecque, Laetitia; Albano, Laetitia

    2016-01-01

    Abstract Background: Ureteral stenosis is part of the common complications of renal graft reported in 3% to 7% of cases. Multiple treatments have been introduced regarding length and position of the stenosis. Metal stents for urologic purpose were created in 1998. Double percutaneous antegrade and transurethral retrograde access to a ureteral stenosis to a long-term metal stent procedure has been rarely described. Case Presentation: Here, we present a case of a ureteral stricture in a double ipsilateral kidney graft with a common ureter. A 67-year-old patient presented with obstructive nephritis associated with acute renal failure 6 years after a double renal graft with a uretero-ureteral end-to-side anastomosis. Abdominal CT scan showed double pelvic dilation. The patient underwent double percutaneous nephrostomies and antegrade pyelogram showed both renal pelvic and ureter dilations caused by a severe chronic ureteral stenosis at junction into the bladder. A Double-J ureteric stent was then inserted retrogradely over a guidewire as first-line treatment. Due to recurrent urinary tract infections (UTIs), removal and replacement of Double-J stents were carried out by placing a thermoexpandable metal stent Memokath® 051 (Bard, Pnn Medical) through the common ureter by a double antegrade and retrograde approach. Treatment was effective with a good renal function maintained after a 3-year follow-up without UTIs. Conclusion: Double antegrade and retrograde access to a long-term metal stent treatment can be seen as an alternative treatment to either endoscopy or open surgery. Further studies should be continued using larger series. PMID:27704056

  10. 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.

  11. Does endovascular treatment of infra-inguinal arterial disease with drug-eluting stents offer better results than angioplasty with or without bare metal stents?

    PubMed

    Antoniou, George A; Georgakarakos, Efstratios I; Antoniou, Stavros A; Georgiadis, George S

    2014-08-01

    A best evidence topic in vascular and endovascular surgery was developed according to a structured protocol. The question addressed was whether treatment of infra-inguinal arterial occlusive disease with drug-eluting stents (DESs) provides improved outcomes compared with bare metal stents (BMSs) or percutaneous balloon angioplasty (PTA) alone. Altogether, 136 papers were found using the reported searches, of which 5 provided the best evidence to answer the question. All papers represent either level 1 or 2 evidence. The authors, journal, date, country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Main outcome measures varied among the studies, and included patency, in-stent restenosis, target lesion revascularization, major adverse events, clinical improvement and limb salvage. Evidence on the comparative efficacy of DESs in femoro-popliteal arterial disease is mainly based on two randomized, controlled trials. Paclitaxel-eluting stents were evaluated in the Zilver PTX trial and demonstrated superior 2-year results to either BMSs or PTA, as indicated/shown by patency (DES vs PTA, 74.8 vs 26.5%, P < 0.01), clinical benefit (DES vs PTA, P < 0.01) and event-free survival (DES vs PTA, 86.6 vs 77.9%, P = 0.02). However, the SIROCCO trial found that the sirolimus-eluting stent did not exhibit statistically significant differences in 2-year in-stent restenosis (22.9 vs 21.1%) and target lesion revascularization (6 vs 13%) compared with the BMS. Treatment of infra-politeal arterial disease with DESs was related with superior outcomes to those of BMSs, as indicated/shown by patency, freedom from target lesion revascularization and freedom from major adverse events. Furthermore, the ACHILLES trial, the only published trial comparing the infra-popliteal DES with PTA, revealed lower angiographic restenosis (22.4 vs 41.9%, P = 0.019) and greater vessel patency (75 vs 57.1%, P = 0.025) in the DES group at 1 year

  12. Bioresorbable Stents in PCI.

    PubMed

    Lindholm, Daniel; James, Stefan

    2016-08-01

    The evolution of percutaneous coronary intervention has been considerable. Coronary stents were introduced to avoid vessel recoil and reduce acute and late vessel complications. Later, drug-eluting stents were developed to decrease the neointimal hyperplasia associated with bare metal stents in order to reduce restenosis. However, very late stent thrombosis remains problematic, and the permanent presence of a metal stent could be associated with local inflammation and impaired vascular physiology. Thus, bioresorbable stents have been developed, to prevent recoil initially when this risk is the highest, with subsequent degradation over time, to avoid long-term complications of the presence of stents in the coronary vasculature. Here, we review the current status of bioresorbable stents in percutaneous coronary intervention (PCI), with focus on the platforms that have been studied the most: ABSORB, DESolve, and DREAMS. In terms of clinical outcomes, bioresorbable stents have not yet shown superiority compared with current generation drug-eluting stents, but rather a signal of increased stent thrombosis. Further development and longer-term studies are needed before the routine implementation of bioresorbable stents in clinical practice. PMID:27312934

  13. Impact on in-hospital outcomes with drug-eluting stents versus bare-metal stents (from 665,804 procedures).

    PubMed

    Badheka, Apurva O; Arora, Shilpkumar; Panaich, Sidakpal S; Patel, Nileshkumar J; Patel, Nilay; Chothani, Ankit; Mehta, Kathan; Deshmukh, Abhishek; Singh, Vikas; Savani, Ghanshyambhai T; Agnihotri, Kanishk; Grover, Peeyush; Lahewala, Sopan; Patel, Achint; Bambhroliya, Chirag; Kondur, Ashok; Brown, Michael; Elder, Mahir; Kaki, Amir; Mohammad, Tamam; Grines, Cindy; Schreiber, Theodore

    2014-12-01

    Contemporary large-scale data, regarding in-hospital outcomes depending on the types of stent used for percutaneous coronary intervention (PCI) is lacking. We queried the Healthcare Cost and Utilization Project's Nationwide Inpatient Sample from 2006 to 2011 using the International Classification of Diseases, Ninth Revision, Clinical Modification procedure code 36.06 (bare-metal coronary artery stent, BMS) or 36.07 (drug-eluting coronary artery stent, DES) for PCI. All analyses were performed using the designated weighting specified to the Nationwide Inpatient Sample database to minimize bias. Primary outcome was in-hospital mortality. Wald's chi-square test was used for categorical variables. We built a hierarchical 2 level model adjusted for multiple confounding factors, with hospital identification incorporated as random effects in the model and propensity match analyses were used to adjust confounding variables. A total of 665,804 procedures were analyzed, which were representative of 3,277,884 procedures in the United States. Use of bare-metal stents (BMS) was associated with greater occurrence of in-hospital mortality compared with that of drug-eluting stents (DES; 1.4% vs 0.5%, p <0.001). The association stayed significant after adjustment of various possible confounding factors (odds ratio for DES versus BMS 0.59 [0.54 to 0.64, p <0.001]) and also in propensity matched cohorts (1.2% vs 0.7%, p <0.001). The results continued to be similar in the following high-risk subgroups: diabetes (0.57 [0.50 to 0.64, <0.001]), acute myocardial infarction and/or shock (0.53 [0.49 to 0.57, <0.001]), age >80 (0.66 [0.58 to 0.74, <0.001]), and multivessel PCI (0.55 [0.46 to 0.66, <0.001]). In conclusion, DES use was associated with lesser in-hospital mortality compared with BMS. This outcome benefit was seen across subgroups in various subgroups including elderly, diabetics, and acute myocardial infarction as well as multivessel interventions. PMID:25439448

  14. 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.

  15. 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. PMID:24115449

  16. Fluoroscopic management of complications after colorectal stent placement.

    PubMed

    Lopera, Jorge E; De Gregorio, Miguel Angel

    2010-09-01

    Colorectal self-expanding metal stents have been widely used as a bridge to surgery in patients with acute malignant colonic obstruction by allowing a single-stage operation, or as a definitive palliative procedure in patients with inoperable tumors. Colonic stents are placed under either fluoroscopic or combined endoscopic and fluoroscopic guidance, with similar technical-success and complication rates. Placement of colonic stents is a very safe procedure with a low procedure-related mortality rate, but serious complications can develop and reinterventions are not uncommon. Most of the complications can be treated by minimally invasive or conservative techniques, while surgical interventions are required for most patients with perforation.

  17. 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

  18. Surface modification of metallic cardiovascular stents by strongly adhering aliphatic polyester coatings.

    PubMed

    Jérôme, Christine; Aqil, Abdelhafid; Voccia, Samuël; Labaye, David-Emmanuel; Maquet, Véronique; Gautier, Sandrine; Bertrand, Olivier F; Jérôme, Robert

    2006-03-01

    This article reports on a novel two-step strategy for the coating of cardiovascular stents by strongly adhering biocompatible and biodegradable aliphatic polyesters. First, a precoating of poly(ethylacrylate) (PEA) was electrografted onto the metallic substrate by cathodic reduction of the parent monomer in dimethylformamide (DMF). The electrodeposition of PEA, in a good solvent of it, was confirmed by both Infra-red and Raman spectroscopies. The pendant ester groups of PEA were then chemically reduced into aluminum alkoxides, able to initiate the ring-opening polymerization (ROP) of either D,L-lactide (LA) or epsilon-caprolactone (CL). Growth of biodegradable PLA or PCL coatings from the adhering precoating was confirmed by both Infra-red and Raman spectroscopies, and directly observed by scanning electron microscopy (SEM). This type of coating can act as an anchoring layer for the subsequent casting of drug-loaded polyester films allowing the controlled release of antiproliferative agents for the treatment of in-stent restenosis. PMID:16317721

  19. 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

  20. 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.

  1. 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.

  2. Endoscopic Ultrasound-Guided Biliary Drainage Using a Fully Covered Metallic Stent after Failed Endoscopic Retrograde Cholangiopancreatography.

    PubMed

    Guo, Jintao; Sun, Siyu; Liu, Xiang; Wang, Sheng; Ge, Nan; Wang, Guoxin

    2016-01-01

    Background and Study Aims. Endoscopic ultrasound- (EUS-) guided biliary drainage (EUS-BD) is an alternative treatment for biliary obstruction after failed endoscopic retrograde cholangiopancreatography (ERCP). In this study, we present the outcomes of inpatients with obstructive jaundice treated with EUS-BD using a fully covered metallic stent after failed ERCP. Patients and Methods. A total of 21 patients with biliary obstruction due to malignant tumors and prior unsuccessful ERCP underwent EUS via an intra- or extrahepatic approach with fully covered metallic stent between March 2014 and October 2015. A single endoscopist performed all procedures. Results. Seven patients underwent hepatogastrostomy (HGS) and 14 underwent choledochoduodenostomy (CDS). The technical and clinical success rates were both 100%. There was no difference in efficacy between HGS and CDS. Adverse events occurred in three patients, including two in the HGS group (1 bile leakage and 1 sepsis) and one in the CDS group (sepsis). Four patients died as a result of their primary tumors during a median follow-up period of 13 months (range: 3-21 months). No patient presented with stent migration. Conclusion. EUS-BD using a fully covered metallic stent appears to be a safe and effective method for the treatment of obstructive jaundice. PMID:27594881

  3. Process for making electroformed stents

    DOEpatents

    Hines, Richard A.

    2000-02-01

    This invention is directed to an expandable stent useful for implantation into an artery or the like. The stents are made using electroforming techniques in which an electrically-conductive mandrel is coated with a suitable resist material, after which the resist is exposed to an appropriate light pattern and frequency so as to form a stent pattern in the resist. The mandrel is then electroplated with a suitable stent material. The mandrel is etched away once a sufficient layer of stent material is deposited, leaving a completed stent.

  4. Memokath Metallic Stent in the Treatment of Transplant Kidney Ureter Stenosis or Occlusion

    SciTech Connect

    Boyvat, Fatih E-mail: boyvatf@yahoo.com; Aytekin, Cuneyt; Colak, Turan; Firat, Ali; Karakayali, Hamdi; Haberal, Mehmet

    2005-04-15

    Purpose. To determine the efficacy of the Memokath 051 stent (Engineers and Doctors, Hornbaek, Denmark) in the treatment of recurrent ureteral stenosis or occlusion in transplant kidneys. Methods. From October 1985 through January 2004, 1,131 renal transplantations were performed at our center. Four patients who developed recurrent renal transplant ureter obstruction had nephrostomy catheters placed. Antegrade pyelography showed ureteral stenosis in three cases and complete occlusion in one patient. In each case, a Memokath 051 stent was inserted via an antegrade approach. Mean follow-up was 20 months (range 18-21 months). Creatinine levels were measured and ultrasonography was performed during follow-up. Results. All stent procedures were technically successful. During follow-up, one stent migrated within 10 days after stent insertion and was removed cystoscopically. Another stent had to be removed in the 14th month due to resistant infection, and was replaced with a new Memokath 051 stent which remained patent for another 8 months. The other two stents were fully patent at the 18th and 21st month of follow-up, respectively. Conclusion. Placement of a Memokath 051 stent appears to be a promising treatment alternative to balloon dilation, double-J stents and open surgical intervention for ureteral stenosis or occlusion in kidney transplant recipients. Further study of larger series is necessary.

  5. Percutaneous Placement of Metallic Stents in Malignant Biliary Obstruction: One-Stage or Two-Stage Procedure? Pre-Dilate or Not?

    SciTech Connect

    Inal, Mehmet; Aksungur, Erol; Akguel, Erol; Oguz, Mahmut; Seydaoglu, Guelsah

    2003-02-15

    The aim of this paper was to evaluate the necessity of percutaneous transhepatic catheter drainage and balloon dilation procedures performed before stent insertion. One hundred and twenty-six patients with unresectable malignant biliary obstruction underwent palliative therapy by means of percutaneous transhepatic placement of 183 metallic biliary endoprotheses. Forty-four (35%) patients underwent metallic stent insertion in a one-stage procedure and 82(65%) had undergone percutaneous transhepatic catheter drainage before stent insertion. Balloon dilation of the stenosis before stent placement (pre-dilation) was performed in 53 (42%) of 126 patients. The rate of the 30-day mortality was 11%, with no procedure-related deaths. The total rate of early complications was 29%, and 84% of these complications were due to percutaneous transhepatic catheter drainage and pre-dilation procedures. Percutaneous transhepatic catheter drainage and pre-dilation had no clinical or statistically significant effect on the patients' survival and stent patency rate. Percutaneous transhepatic catheter drainage and balloon dilation increased the cost of stent placement 18% and 19%, respectively. Palliation of malignant biliary obstruction with percutaneous transhepatic stent insertion should be done directly, in the simplest way, without performing percutaneous transhepatic catheter drainage and balloon dilation before stent placement. It is more useful, safe, and cost-effective.

  6. Novel oesophago-gastro-duodenal stenting for gastric leaks after laparoscopic sleeve gastrectomy.

    PubMed

    Liu, Shirley Yuk-Wah; Wong, Simon Kin-Hung; Ng, Enders Kwok-Wai

    2015-01-01

    The management of gastric leak after laparoscopic sleeve gastrectomy (LSG) can be complex and challenging. Whilst operative interventions are mostly complicated and reserved for unstable or refractory cases, endoscopic self-expandable metal stenting (SEMS) is increasingly preferred as a safer treatment option. Yet, SEMS carries the problems of frequent stent migration and inconsistent healing as ordinary SEMS is designed mainly for stenotic disease. We hereby present two cases of early and chronic post-LSG leakage that were respectively failed to be treated by surgery and ordinary SEMS but were successfully managed by a dedicated extra-long oesophago-gastro-duodenal stent. In oesophago-gastro-duodenal stenting, the characteristics of extra-long stent length allow total gastric exclusion between the mid-oesophagus and the first part of duodenum to prevent stent migration and to equalise high pressure gradient within the gastric sleeve to promote fistula healing.

  7. An in vitro model for preclinical testing of thrombogenicity of resorbable metallic stents.

    PubMed

    Walker, Emily K; Nauman, Eric A; Allain, Jean Paul; Stanciu, Lia A

    2015-06-01

    Vascular stents that can biodegrade and disappear in time have been reported as a promising solution to the problems of late-stent thrombosis and in-stent restenosis. Iron alloys in particular have many advantages in terms of cytocompatibility and mechanical properties. Despite mechanical behavior and biocompatibility studies, little attention has been given to the thrombogenic potential of these stents. This article presents the first study that aims to close this gap by addressing the hemocompatibility of resorbable iron-based alloys and composites in an in vitro porcine blood model. The investigated braided biodegradable stents included 99.95% pure Fe (50% cold worked), Fe35Mn alloy, Fe35Mn-25% ZM21 (ZM21 is 2% Zn, 0.5% Mn, balance Mg), Fe-25% Mg, and Fe-57% Mg. All stents were formed by braiding 127 µm diameter wires into stents with an outer diameter of 6.35 mm. Inflammatory reaction and thrombocyte activation were examined by assessment of β-thromboglobulin, thrombin-antithrombin complex, and polymorphonuclear elastase levels. The potential of Fe35Mn for use in vascular stenting is demonstrated by its exhibition of the least thrombogenic potential among tested materials. All bioresorbable Fe-Mn alloy compositions showed a reduced propensity towards platelet adhesion compared to 316L stainless steel, further indicating a general positive shift towards reduced thrombogenicity compared to traditional stents.

  8. Early pain detection and management after esophageal metal stent placement in incurable cancer patients: A prospective observational cohort study

    PubMed Central

    Reijm, Agnes N.; Didden, Paul; Bruno, Marco J.; Spaander, Manon C.W.

    2016-01-01

    Background and study aims: Studies of esophageal self-expandable metal stents (SEMS) mainly focus on efficacy and recurrent dysphagia. Retrosternal pain has been described in up to 14 % of these patients, however, prospective daily pain assessment has not yet been performed. We conducted a prospective study to evaluate the occurrence and management of pain after esophageal SEMS deployment. Patients and methods: A total of 65 patients who underwent SEMS placement for incurable malignant esophageal stenosis were included. Patients used a diary to record intensity of pain twice daily for 2 weeks, according to the Numeric Rating Scale (NRS). A pain score ≥ 4 was used to determine whether patients experienced significant pain. If pain occurred, acetaminophen was used and, in cases of ongoing pain, an opiate was prescribed. Dose, duration, and kind of analgesic were noted. Results: The rate of significant pain increased from 0 % at baseline to 60 % on Day 1 (P < 0.001), followed by 37 % and 25 % on Days 7 and 14, respectively. The rate of analgesics use increased from 20 % at baseline to 78 % on Day 1 (P < 0.001), followed by 72 % and 62 % on Days 7 and 14, respectively. The use of opiates increased from 14 % at baseline to 42 % on Day 1 (P < 0.001). No variables associated with SEMS related pain were found. Conclusions: Two-thirds of patients experience significant pain after esophageal SEMS insertion and analgesics, including opiates, are frequently required. Patients need to be informed and preventive prescription of analgesia should be considered in order to improve quality of life. PMID:27540579

  9. Stent-grafts for the treatment of TIPS dysfunction: Fluency stent vs Wallgraft stent

    PubMed Central

    Luo, Xue-Feng; Nie, Ling; Wang, Zhu; Tsauo, Jiaywei; Liu, Ling-Jun; Yu, Yang; Zhou, Biao; Tang, Cheng-Wei; Li, Xiao

    2013-01-01

    AIM: To evaluate the clinical efficacy of an expanded polytetrafluoro-ethylene-covered Fluency stent compared with that of a polyethylene terephthalate-covered Wallgraft stent for the management of transjugular intrahepatic portosystemic shunt (TIPS) dysfunction. METHODS: A retrospective review of patients who underwent TIPS revision with stent-grafts between May 2007 and June 2011 was conducted. The patients were divided into two groups according to the stent-grafts implanted: the Fluency stent (Bard Incorporated, Karlsruhe, Germany) and the Wallgraft stent (Boston Scientific, Galway, Ireland). The primary patency rates were calculated and compared using the Kaplan-Meier method. RESULTS: A total of 73 patients were evaluated in this study: 33 with Fluency stents and 40 with Wallgraft stents. The primary patency rates at 12 and 24 mo were 91% and 85%, respectively, in the Fluency stent group and 78% and 63%, respectively, in the Wallgraft stent group. The primary shunt patency rates after TIPS revision were significantly better with the Fluency stent than with the Wallgraft stent (P = 0.033). CONCLUSION: TIPS revision with the Fluency stent has higher medium-term patency rates than that with the Wallgraft stent. PMID:23946607

  10. Drug-eluting stents to prevent stent thrombosis and restenosis.

    PubMed

    Im, Eui; Hong, Myeong-Ki

    2016-01-01

    Although first-generation drug-eluting stents (DES) have significantly reduced the risk of in-stent restenosis, they have also increased the long-term risk of stent thrombosis. This safety concern directly triggered the development of new generation DES, with innovations in stent platforms, polymers, and anti-proliferative drugs. Stent platform materials have evolved from stainless steel to cobalt or platinum-chromium alloys with an improved strut design. Drug-carrying polymers have become biocompatible or biodegradable and even polymer-free DES were introduced. New limus-family drugs (such as everolimus, zotarolimus or biolimus) were adopted to enhance stent performances. As a result, these new DES demonstrated superior vascular healing responses on intracoronary imaging studies and lower stent thrombotic events in actual patients. Recently, fully-bioresorbable stents (scaffolds) have been introduced, and expanding their applications. In this article, the important concepts and clinical results of new generation DES and bioresorbable scaffolds are described. PMID:26567863

  11. Drug-eluting stents to prevent stent thrombosis and restenosis.

    PubMed

    Im, Eui; Hong, Myeong-Ki

    2016-01-01

    Although first-generation drug-eluting stents (DES) have significantly reduced the risk of in-stent restenosis, they have also increased the long-term risk of stent thrombosis. This safety concern directly triggered the development of new generation DES, with innovations in stent platforms, polymers, and anti-proliferative drugs. Stent platform materials have evolved from stainless steel to cobalt or platinum-chromium alloys with an improved strut design. Drug-carrying polymers have become biocompatible or biodegradable and even polymer-free DES were introduced. New limus-family drugs (such as everolimus, zotarolimus or biolimus) were adopted to enhance stent performances. As a result, these new DES demonstrated superior vascular healing responses on intracoronary imaging studies and lower stent thrombotic events in actual patients. Recently, fully-bioresorbable stents (scaffolds) have been introduced, and expanding their applications. In this article, the important concepts and clinical results of new generation DES and bioresorbable scaffolds are described.

  12. 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.

  13. Duodenal stents for malignant duodenal strictures.

    PubMed Central

    Johnston, S. D.; McKelvey, S. T. D.; Moorehead, R. J.; Spence, R. A. J.; Tham, T. C. K.

    2002-01-01

    Duodenal obstruction may be caused by inoperable malignant disease. Symptoms of nausea and vomiting have been traditionally palliated by surgery. The aim of the study was to determine the efficacy of the endoscopic placement of metal self expanding duodenal stents for the palliation of malignant duodenal obstruction. Four patients with malignant gastric outlet obstruction are described. One patient had a history of oesophagectomy for oesophageal adenocarcinoma and presented with further dysphagia. At endoscopy the recurrent oesophageal tumour and an adenocarcinoma involving the pylorus were both stented. In the other three patients there was a previous history of colonic carcinoma, cholangiocarcinoma and oesophageal adenocarcinoma respectively. All four patients were successfully stented with good palliation of their symptoms. Duodenal Wallstents are a useful alternative to surgery in patients with inoperable malignant duodenal obstruction or those who are unfit for surgery. Images Fig 1 Fig 2 PMID:12137161

  14. Gel phantom study with high-intensity focused ultrasound: influence of metallic stent containing either air or fluid.

    PubMed

    Kang, Koung Mi; Lee, Jae Young; Kim, Haeri; Han, Joon Koo; Choi, Byung-Ihn

    2014-12-01

    We aimed to investigate whether a cylindrical structure containing either air or fluid and with or without a metallic stent affects the volume and density of cavitation produced by high-intensity focused ultrasound via a gel phantom study. Sixteen tissue-mimicking phantoms based on a polyacrylamide gel mixed with bovine serum albumin with a cylindrical hole 1 cm in diameter and 7.5 cm in length were divided into four groups of four phantoms with air in the holes (group 1), four phantoms with fluid in the holes (group 2), four phantoms with air-containing metallic stents (group 3) and four phantoms with fluid-containing metallic stents (group 4). A pulsed high-intensity focused ultrasound beam (50% duty cycle, 40-Hz pulse repetition frequency) at 75 W of acoustic power was directed perpendicularly to the longitudinal axis of the hole, with its focus at the posterior wall of the hole. The size of the cavitation on the x-, y-, and z-axes was measured, and the volumes of cavitation and coagulation were calculated using the formula for the volume of an elliptical cone. The density of cavitation was measured in the tissue phantom anterior to the hole with a 1 × 1-cm square region of interest. For statistical analysis, the Kruskal-Wallis test and Mann-Whitney U-test were used. The phantoms with air-containing holes (groups 1 and 3) developed larger and denser cavitations anterior to the focus, without unnecessary coagulation posterior to the focus, compared with the phantoms with fluid-containing holes (groups 2 and 4), regardless of the presence of stents. All of the axes and volumes of the anterior cavitations were significantly larger than those of the posterior cavitations in groups 1 and 3 (all p-values <0.05). The results of this study might be applied to maximize cavitation to enhance drug delivery into tumors.

  15. 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.

  16. 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)

  17. Efficacy of Covered Metallic Stents in the Treatment of Unresectable Malignant Biliary Obstruction

    SciTech Connect

    Miyayama, Shiro Matsui, Osamu; Akakura, Yukari; Yamamoto, Toru; Nishida, Hiroto; Yoneda, Kenji; Kawai, Keiichi; Toya, Daisyu; Tanaka, Nobuyoshi; Mitsui, Takeshi; Asada, Yasuyuki

    2004-08-15

    We evaluated the efficacy of covered stents for malignant biliary obstruction. We studied 62 patients with obstruction distal to the hilar confluence who survived longer than 10 weeks and divided them into a covered stent group (group 1, n = 22), a Z stent group (group 2, n = 19), and a mesh stent group (group 3, n = 21), according to their type of the stent. Patency rates of each group were compared. Early stent revision was required after 3 days in 18% (4/22) of group 1, 26% (5/19) of group 2, and 0% (0/21) of group 3. The 10, 20, and 40-week primary patency rates were 77%, 77%, and 59% (group 1), 42%, 25%, and 8% (group 2), and 76%, 71%, and 55% (group 3), respectively. Primary patency rates of groups 1 and 3 were significantly higher than those of group 2 (p < 0.05), and there was no statistically difference between those of group 1 and group 3. The 10, 20, and 40-week assisted primary (secondary) patency rates were 96%, 96%, and 96% (group 1), 68%, 49%, and 39% (group 2), and 86%, 74%, and 58% (group 3), respectively. Assisted primary patency (secondary) rates of group 1 were significantly higher than those of groups 2 and 3 (p < 0.01 and p < 0.05, respectively). Our study suggests that the primary patency rates of the covered stents are equal to those of mesh stents, but these may be improved further if covered stents, which avoid the need for early revision, are used.

  18. Comparison of in vitro human endothelial cell response to self-expanding stent deployment in a straight and curved peripheral artery simulator

    PubMed Central

    Ghriallais, Ríona Ní; McNamara, Laoise; Bruzzi, Mark

    2013-01-01

    Haemodynamic forces have a synergistic effect on endothelial cell (EC) morphology, proliferation, differentiation and biochemical expression profiles. Alterations to haemodynamic force levels have been observed at curved regions and bifurcations of arteries but also around struts of stented arteries, and are also known to be associated with various vascular pathologies. Therefore, curvature in combination with stenting might create a pro-atherosclerotic environment compared with stenting in a straight vessel, but this has never been investigated. The goal of this study was to compare EC morphology, proliferation and differentiation within in vitro models of curved stented peripheral vessel models with those of straight and unstented vessels. These models were generated using both static conditions and also subjected to 24 h of stimulation in a peripheral artery bioreactor. Medical-grade silicone tubes were seeded with human umbilical vein endothelial cells to produce pseudovessels that were then stented and subjected to 24 h of physiological levels of pulsatile pressure, radial distention and shear stress. Changes in cell number, orientation and nitric oxide (NO) production were assessed in straight, curved, non-stented and stented pseudovessels. We report that curved pseudovessels lead to higher EC numbers with random orientation and lower NO production per cell compared with straight pseudovessels after 24 h of biomechanical stimulation. Both stented curved and stented straight pseudovessels had lower NO production per cell than corresponding unstented pseudovessels. However, in contrast to straight stented pseudovessels, curved stented pseudovessels had fewer viable cells. The results of this study show, for the first time, that the response of the vascular endothelium is dependent on both curvature and stenting combined, and highlight the necessity for future investigations of the effects of curvature in combination with stenting to fully understand effects on

  19. 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

  20. 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.

  1. Endoscopic ultrasound-guided placement of AXIOS stent for drainage of pancreatic fluid collections

    PubMed Central

    Patil, Rashmee; Ona, Mel A.; Papafragkakis, Charilaos; Anand, Sury; Duddempudi, Sushil

    2016-01-01

    Pancreatic fluid collections (PFCs) have conventionally been treated with surgery, percutaneous drainage, or with the more recently established endoscopic ultrasound (EUS)-guided drainage modality. Currently, endoscopic plastic or metallic stents are used for PFC drainage. Plastic stents present issues with stent migration and premature occlusion requiring frequent stent exchanges or placement of additional stents. Metallic stents are tubular and may migrate, resulting in inefficient drainage, content leakage, retrieval and replacement, and possible mucosal injury. The aim of this review was to summarize and evaluate the clinical and technical effectiveness of EUS-guided placement of the recently developed AXIOS stent, a lumen-apposing self-expandable metallic stent (LASEMS)for PFC drainage. A literature review was performed to identify the studies describing this technique. In this review article we have summarized case series or reports describing EUS-guided LASEMS placement. The indications, techniques, limitations and complications reported are discussed. A total of 298 patients were included across all studies described thus far in the literature. Overall, a 97% technical success rate and a 96% clinical success rate have been reported. Early and late complications related to the placement or removal of LASEMS have been reported, however few cases have presented life-threatening results. EUS-guided PFC drainage and LASEMS placement can be a safe and effective alternative approach in the management of selected patients. PMID:27065729

  2. 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

  3. Severe compression of a bailout self-expanding chimney stent for rescuing the miscoverage of left common carotid artery during TEVAR of a type B aortic dissection.

    PubMed

    Wang, Lixin; Guo, Daqiao; Jiang, Junhao; Shi, Zhenyu; Fu, Weiguo; Wang, Yuqi

    2014-04-01

    A 54-year-old man who suffered from paraplegia due to type B aortic dissection was treated with a Valiant stent-graft. However, attempts to gain secure proximal sealing resulted in an inadvertent coverage of the left common carotid artery by the endograft. The blood flow in the left common carotid artery was restored by a transcarotid Smart Control stent in a chimney fashion. At 6- and 18-month follow-up, computed tomography scan showed that the chimney stent was severely compressed by the stent graft, although the patient remained neurologically asymptomatic. PMID:24309751

  4. Spectral Imaging for Intracranial Stents and Stent Lumen

    PubMed Central

    Chen, David Yen-Ting; Chen, Chi-Jen; Hsu, Hui-Ling

    2016-01-01

    Introduction Application of computed tomography for monitoring intracranial stents is limited because of stent-related artifacts. Our purpose was to evaluate the effect of gemstone spectral imaging on the intracranial stent and stent lumen. Materials and Methods In vitro, we scanned Enterprise stent phantom and a stent–cheese complex using the gemstone spectral imaging protocol. Follow-up gemstone spectral images of 15 consecutive patients with placement of Enterprise from January 2013 to September 2014 were also retrospectively reviewed. We used 70-keV, 140-keV, iodine (water), iodine (calcium), and iodine (hydroxyapatite) images to evaluate their effect on the intracranial stent and stent lumen. Two regions of interest were individually placed in stent lumen and adjacent brain tissue. Contrast-to-noise ratio was measured to determine image quality. The maximal diameter of stent markers was also measured to evaluate stent-related artifact. Two radiologists independently graded the visibility of the lumen at the maker location by using a 4-point scale. The mean of grading score, contrast/noise ratio and maximal diameter of stent markers were compared among all modes. All results were analyzed by SPSS version 20. Results In vitro, iodine (water) images decreased metallic artifact of stent makers to the greatest degree. The most areas of cheese were observed on iodine (water) images. In vivo, iodine (water) images had the smallest average diameter of stent markers (0.33 ± 0.17mm; P < .05) and showed the highest mean grading score (2.94 ± 0.94; P < .05) and contrast/noise ratio of in-stent lumen (160.03 ±37.79; P < .05) among all the modes. Conclusion Iodine (water) images can help reduce stent-related artifacts of Enterprise and enhance contrast of in-stent lumen. Spectral imaging may be considered a noninvasive modality for following-up patients with in-stent stenosis. PMID:26731534

  5. Use of self-expanding covered stent and negative pressure wound therapy to manage late rectal perforation after injury from an improvised explosive device: a case report.

    PubMed

    Ozer, M Tahir; Coskun, Ali K; Sinan, Huseyin; Saydam, Mehmet; Akay, Emin O; Peker, Subutay; Ogunc, Gokhan; Demirbas, Sezai; Peker, Yusuf

    2014-06-01

    Blast injuries, caused by explosions accompanied by high-pressure waves, produce tissue damage in the acute period, followed in the later period by circulatory disorders due to vascular endothelial damage and related tissue necrosis. Blunt rectal perforation is rare and difficult to diagnose. In the acute period following blast pelvic injuries, the main objectives are to stop bleeding, minimise contamination and preserve the patient's life. The patient in this report had major vascular injuries, severe pelvic injury and, in the later period, rectal perforation because of vascular endothelial damage caused by the blast effect. Our aim was to treat the patient conservatively because of his poor general condition. We placed a self-expanding covered stent (SECS) into the rectum and then applied negative pressure wound therapy (NPWT; V.A.C.® Therapy, KCI) to the pelvic region and perirectal area. At the end of the treatment, the rectal perforation was closed, and the patient was discharged with healing. In this article, we discuss the novel use of an SECS with NPWT and review related literature.

  6. Use of self-expanding covered stent and negative pressure wound therapy to manage late rectal perforation after injury from an improvised explosive device: a case report.

    PubMed

    Ozer, M Tahir; Coskun, Ali K; Sinan, Huseyin; Saydam, Mehmet; Akay, Emin O; Peker, Subutay; Ogunc, Gokhan; Demirbas, Sezai; Peker, Yusuf

    2014-06-01

    Blast injuries, caused by explosions accompanied by high-pressure waves, produce tissue damage in the acute period, followed in the later period by circulatory disorders due to vascular endothelial damage and related tissue necrosis. Blunt rectal perforation is rare and difficult to diagnose. In the acute period following blast pelvic injuries, the main objectives are to stop bleeding, minimise contamination and preserve the patient's life. The patient in this report had major vascular injuries, severe pelvic injury and, in the later period, rectal perforation because of vascular endothelial damage caused by the blast effect. Our aim was to treat the patient conservatively because of his poor general condition. We placed a self-expanding covered stent (SECS) into the rectum and then applied negative pressure wound therapy (NPWT; V.A.C.® Therapy, KCI) to the pelvic region and perirectal area. At the end of the treatment, the rectal perforation was closed, and the patient was discharged with healing. In this article, we discuss the novel use of an SECS with NPWT and review related literature. PMID:24851734

  7. Comparison of Bare Metal and Drug-Eluting Stents in Patients with Chronic Kidney Disease (From the NHLBI Dynamic Registry)

    PubMed Central

    Green, Sandy M.; Selzer, Faith; Mulukutla, Suresh R.; Tadajweski, Edward J.; Green, Jamie A.; Wilensky, Robert L.; Laskey, Warren K.; Cohen, Howard A.; Rao, Sunil V.; Weisbord, Steven D.; Lee, Joon S.; Reis, Steven E.; Kip, Kevin E.; Kelsey, Sheryl F.; Williams, David O.; Marroquin, Oscar C.

    2011-01-01

    Patients with chronic kidney disease (CKD) have a disproportionate burden of coronary artery disease and commonly undergo revascularization. The role and safety of percutaneous coronary intervention (PCI) using drug eluting stents (DES) verses bare metal stents (BMS) in CKD patients not on renal replacement therapy has not been fully evaluated. This study investigated the efficacy and safety of DES in patients with CKD not on renal replacement therapy. Patients where drawn from the National Heart, Lung, and Blood Institute Dynamic Registry and were stratified by renal function based on estimated glomerular filtration rate (GFR). Of the 4157 participants, 1108 had CKD (“low-GFR” <60 ml/min/1.73m2), while 3049 patients had normal renal function (“normal-GFR”≥60 ml/min/1.73m2). For each strata of renal function, we compared the risk of death, myocardial infarction (MI), or repeat revascularization between subjects who received DES and BMS at the index procedure. Patients with low-GFR had higher one-year rates of death and MI and a decreased rate of repeat revascularization when compared to patients with a normal-GFR. The use of DES was associated with a decreased need for repeat revascularization in the normal-GFR group (adjusted hazard ratio [HR] 0.63, 95% CI 0.50–0.79, p<0.001) but not in the low-GFR group (HR 0.69, 95% CI 0.45–1.06, p=0.09). The risks of death and MI were not different between the two stents in either patient population. In conclusion, the presence of CKD predicted poor outcomes after PCI with high rates of mortality regardless of stent type. The effect of DES in reducing repeat revascularization appeared to be attenuated in these patients. PMID:21890077

  8. Development of Biliary and Enteral Stents by the Korean Gastrointestinal Endoscopists

    PubMed Central

    Shim, Chan Sup; Kim, Jin Hong; Bok, Gene Hyun

    2016-01-01

    Stenting in the gastrointestinal tract is a common procedure used for palliation of obstruction in the enteral and biliary tract. Today, stenting of malignant and benign strictures is performed at almost every major tertiary hospital in Korea. Moreover, Korea has become a major global supplier of cutting edge technology in the field of self-expanding metal stents. However, the history of stenting in Korea is relatively short and was far behind that of other nations such as Japan and Germany. The authors are humbled and gratified to have been able to observe the development and application of these stents in Korea, first hand. In this article, the authors review the overall history of stenting with a specific focus on the development of stenting in Korea. The development of esophageal, gastroduodenal, biliary, and colonic stents in Korea are reviewed in this article from a chronological and historical point of view, and a personal account of some of the significant moments of stent development in Korea are described. PMID:26956192

  9. Biodegradable stents with elastic memory.

    PubMed

    Venkatraman, Subbu S; Tan, Lay Poh; Joso, Joe Ferry D; Boey, Yin Chiang Freddy; Wang, Xintong

    2006-03-01

    This work reports, for the first time, the development of a fully biodegradable polymeric stent that can self-expand at body temperatures (approximately 37 degrees C), using the concept of elastic memory. This self-expansion is necessary in fully polymeric stents, to overcome the problem of elastic recoil following balloon expansion in a body vessel. Bi-layered biodegradable stent prototypes were produced from poly-L-lactic acid (PLLA) and poly glycolic acid (PLGA) polymers. Elastic memory was imparted to the stents by temperature conditioning. The thickness and composition of each layer in the stents are critical parameters that affect the rate of self-expansion at 37 degrees C, as well as the collapse strengths of the stents. The rate of self-expansion of the stents, as measured at 37 degrees C, exhibits a maximum with layer thickness. The Tg of the outer layer is another significant parameter that affects the overall rate of expansion.

  10. Dose perturbation of a novel cobalt chromium coronary stent on {sup 32}P intravascular brachytherapy: A Monte Carlo study

    SciTech Connect

    Mourtada, Firas; Horton, John L.

    2005-01-01

    Intravascular brachytherapy has been adopted for the indication of in-stent restenosis on the basis of results of clinical trials using mainly stainless steel stents. Recently, a new stent made of cobalt-chromium L-605 alloy (CoCr, {rho}=9.22 g/cm{sup 3}) (MULTI-LINK VISION{sup TM}) was introduced as an alternative to the 316L stainless steel stent design (SS, {rho}=7.87 g/cm{sup 3}) (MULTI-LINK PENTA{sup TM}). In this work, we used the Monte Carlo code MCNPX to compare the dose distribution for the {sup 32}P GALILEO{sup TM} source in CoCr and SS 8 mm stent models. The dose perturbation factor (DPF), defined as the ratio of the dose in water with the presence of a stent to the dose without a stent, was used to compare results. Both stent designs were virtually expanded to diameters of 2.0, 3.0, and 4.0 mm using finite element models. The complicated strut shapes of both the CoCr and SS stents were simplified using circular rings with an effective width to yield a metal-to-tissue ratio identical to that of the actual stents. The mean DPF at a 1 mm tissue depth, over the entire stented length of 8 mm, was 0.935 for the CoCr stent and 0.911 for the SS stent. The mean DPF at the intima (0.05 mm radial distance from the strut outer surface), over the entire stented length of 8 mm, was 0.950 for CoCr, and 0.926 for SS. The maximum DPFs directly behind the CoCr and SS struts were 0.689 and 0.644, respectively. All DPF estimates have a standard deviation of {+-}0.6%(k=2), approximating the 95% confidence interval. Although the CoCr stent has a higher effective atomic number and greater density than the SS stent, the DPFs for the two stents are similar, probably because the metal-to-tissue ratio and strut thickness of the CoCr stent are lower than those of the SS stent.

  11. Expanding iClick to group 9 metals

    DOE PAGES

    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.

  12. 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.

  13. Bleeding Risk of Stent Removal After EUS-Guided Cystgastrostomy and Metal Stent Placement for Drainage of a Pancreatic Fluid Collection.

    PubMed

    Jalali, Farid; Samarasena, Jason; Lee, John G

    2016-07-01

    Endoscopists are keenly aware of bleeding risks during and immediately after cystgastrostomy and reduce this risk by endoscopic ultrasound guidance to avoid manipulation near major vessels. Bleeding risk associated with cystgastrostomy stent removal after resolution of a pancreatic fluid collection, however, is less evident. We present our experience with bleeding during cystgastrostomy stent removal in a patient with resolved walled-off necrosis and will discuss the significance of unexplained spontaneous upper gastrointestinal bleeding in this setting, which may serve as a warning sign for possible stent erosion into major vessels. PMID:27622199

  14. Bleeding Risk of Stent Removal After EUS-Guided Cystgastrostomy and Metal Stent Placement for Drainage of a Pancreatic Fluid Collection

    PubMed Central

    Samarasena, Jason; Lee, John G.

    2016-01-01

    Endoscopists are keenly aware of bleeding risks during and immediately after cystgastrostomy and reduce this risk by endoscopic ultrasound guidance to avoid manipulation near major vessels. Bleeding risk associated with cystgastrostomy stent removal after resolution of a pancreatic fluid collection, however, is less evident. We present our experience with bleeding during cystgastrostomy stent removal in a patient with resolved walled-off necrosis and will discuss the significance of unexplained spontaneous upper gastrointestinal bleeding in this setting, which may serve as a warning sign for possible stent erosion into major vessels. PMID:27622199

  15. Numerical simulation of a novel expanded metal tubular structure for crashworthiness application

    NASA Astrophysics Data System (ADS)

    Abdelaal, A. H. A.; Tarlochan, F.

    2015-12-01

    Search for new geometries and materials that would serve in crashworthiness applications is a cumulative process. Recent studies investigated the performance of expanded metal tubes and the possible ways to enhance its energy absorption capability. The aim of this work is to investigate the crashworthiness characteristics of new concept is proposed where expanded metal tube is suited into a double-walled tube made of the same material to form one structure. The tube was then numerically tested through a verified model using ABAQUS software. Moreover, the influence of the size of the expanded metal cell was also investigated in the present study. The new concept showed an enhanced energy absorption characteristics related to the change in the mass of the tubular structure. The enhancement was related to both the change in deformation pattern, and the increase in crushed mass.

  16. 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

  17. A Comprehensive Review of Esophageal Stents

    PubMed Central

    Hong, Jinwha; Lam-Tsai, Yvette; Gress, Frank

    2012-01-01

    Esophageal stents are important tools for palliative treatment of inoperable esophageal malignancies. With the development of multiple self-expandable stents, there are now several therapeutic options for managing benign and malignant esophageal diseases. This paper discusses the various types of esophageal stents currently available, indications for their placement, challenges and complications that gastroenterologists face when placing these stents, and some of the innovations that will become available in the near future. PMID:23293566

  18. An improved technique of expanding metal ring experiment under high explosive loading.

    PubMed

    Tang, Tiegang; Ren, Guowu; Guo, Zhaoliang; Li, Qingzhong

    2013-04-01

    An experimental technique for metal expanding ring subjected to high explosive loading is conducted to significantly improve the loading stability compared with the traditional setup of two-end detonator initiation. Aspects of the circuit design, experimental arrangement, and initiation principle are illustrated in great detail. In terms of this experimental platform, we examine the velocity response of an individual ring, which demonstrates the experimental reproducibility. Moreover, fragmentation of multiple rings stacked on a metal driver is discussed.

  19. Transjugular Insertion of Bare-Metal Biliary Stent for the Treatment of Distal Malignant Obstructive Jaundice Complicated by Coagulopathy

    SciTech Connect

    Tsauo Jiaywei Li Xiao Li Hongcui Wei Bo Luo Xuefeng Zhang Chunle Tang Chengwei; Wang Weiping

    2013-04-15

    This study was designed to investigate retrospectively the feasibility of transjugular insertion of biliary stent (TIBS) for the treatment of distal malignant obstructive jaundice complicated by coagulopathy. Between April 2005 and May 2010, six patients with distal malignant obstructive jaundice associated with coagulopathy that was unable to be corrected underwent TIBS at our institution for the palliation of jaundice. Patients' medical record and imaging results were reviewed to obtain information about demographics, procedure details, complications, and clinical outcomes. The intrahepatic biliary tract was successfully accessed in all six patients via transjugular approach. The procedure was technically successfully in five of six patients, with a bare-metal stent implanted after traversing the biliary strictures. One procedure failed, because the guidewire could not traverse the biliary occlusion. One week after TIBS, the mean serum bilirubin in the five successful cases had decreased from 313 {mu}mol/L (range 203.4-369.3) to 146.2 {mu}mol/L (range 95.8-223.3) and had further decreased to 103.6 {mu}mol/L (range 29.5-240.9) at 1 month after the procedure. No bleeding, sepsis, or other major complications were observed after the procedure. The mean survival of these five patients was 4.5 months (range 1.9-5.8). On imaging follow-up, there was no evidence of stent stenosis or migration, with 100 % primary patency. When the risks of hemorrhage from percutaneous transhepatic cholangiodrainage are high, TIBS may be an effective alternative for the treatment of distal malignant obstructive jaundice.

  20. Very late mesenteric bare metal stent thrombosis in the setting of cessation of antiplatelet agents.

    PubMed

    Ait-Mokhtar, O; Bayet, G; Benamara, S; Brunet, J; Hager, F X; Sainsous, J

    2015-06-01

    We report a case of a 73 year-old man admitted for acute mesenteric ischaemia. Eight years before, he had a first mesenteric ischaemic event treated by left colectomy and angioplasty of both main coeliac artery (MCA) and superior mesenteric artery (SMA); the patient was discharged on lifelong clopidogrel and aspirin. One month before his admission for the index event, he had a major haematuria; clopidogrel was stopped first, then aspirin because of recurrent haematuria. Five days after withdrawal of both antiplatelet drugs, the patient presented with acute mesenteric ischaemia. Urgent aortography showed in-stent occlusion of SMA and in-stent restenosis of MCA; we performed ad hoc thrombus aspiration of SMA and balloon angioplasty of MCA. The patient was discharged seven days after, without complications. This case shows that very late stent thrombosis in digestive artery can occur in the setting of antiplatelet arrest and urgent endovascular intervention constitutes a seductive alternative for surgery when performed early after symptoms onset.

  1. 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.

  2. Three-dimensional CT imaging and virtual endoscopy for the placement of self-expandable stents in oesophageal and tracheobronchial neoplastic stenoses.

    PubMed

    Di Simone, M P; Mattioli, S; D'Ovidio, F; Bassi, F

    2003-01-01

    We examined the value of multislice computed tomography (CT) with three-dimensional (3D) reconstruction of the images as a pre-treatment examination in order to plan endoluminal stenting in 14 patients with large tumours involving the oesophagus and/or the tracheobronchial tree. The measurement of the stenosis obtained during 3D reconstruction of the CT images corresponded to that obtained by endoscopy and to the prosthesis chosen in all cases, with the exception of one patient undergoing double stenting due to inadequate gaseous distension of the oesophageal lumen. 3D CT may add information with respect to axial imaging, and be helpful to better plan and perform stenting of the oesophagus and airways without burdening the preoperative work-up.

  3. 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.

  4. Degradable metallic biomaterials: design and development of Fe-Mn alloys for stents.

    PubMed

    Hermawan, Hendra; Dubé, Dominique; Mantovani, Diego

    2010-04-01

    Designing materials having suitable mechanical properties and targeted degradation behavior is the key for the development of biodegradable materials for medical applications, including stents. A series of Fe-Mn alloys was developed with the objective to obtain mechanical properties similar to those of stainless steel 316L and degradation behavior more suited than pure iron. Four alloys with Mn content ranging between 20 and 35 wt % were compared in this study. Their microstructure, mechanical properties, magnetic properties as well as degradation behavior were carefully investigated. Results show that their microstructure is mainly composed of gamma phase with the appearance of epsilon phase in alloys having a lower Mn content. The yield strength and elongation of alloys was comprised between 234 MPa and 32% for Fe-35%Mn alloy to 421 MPa and 7.5% for the Fe-20%Mn alloy. All alloys show similar magnetic susceptibility ( approximately 1.8 x 10(-7) m(3)/kg) in the quenched condition. This magnetic susceptibility remains constant after plastic deformation for all the tested alloys except for the Fe-20%Mn alloy. The corrosion rate was higher than pure iron. Among the alloys studied in this work, the Fe-35%Mn alloy shows mechanical properties and degradation behavior closely approaching those required for biodegradable stents application.

  5. Degradable metallic biomaterials: design and development of Fe-Mn alloys for stents.

    PubMed

    Hermawan, Hendra; Dubé, Dominique; Mantovani, Diego

    2010-04-01

    Designing materials having suitable mechanical properties and targeted degradation behavior is the key for the development of biodegradable materials for medical applications, including stents. A series of Fe-Mn alloys was developed with the objective to obtain mechanical properties similar to those of stainless steel 316L and degradation behavior more suited than pure iron. Four alloys with Mn content ranging between 20 and 35 wt % were compared in this study. Their microstructure, mechanical properties, magnetic properties as well as degradation behavior were carefully investigated. Results show that their microstructure is mainly composed of gamma phase with the appearance of epsilon phase in alloys having a lower Mn content. The yield strength and elongation of alloys was comprised between 234 MPa and 32% for Fe-35%Mn alloy to 421 MPa and 7.5% for the Fe-20%Mn alloy. All alloys show similar magnetic susceptibility ( approximately 1.8 x 10(-7) m(3)/kg) in the quenched condition. This magnetic susceptibility remains constant after plastic deformation for all the tested alloys except for the Fe-20%Mn alloy. The corrosion rate was higher than pure iron. Among the alloys studied in this work, the Fe-35%Mn alloy shows mechanical properties and degradation behavior closely approaching those required for biodegradable stents application. PMID:19437432

  6. Use of the Memokath Urethral Stent in the management of ileal conduit stomal stenosis

    PubMed Central

    Pan, Tzong-Yang; Al-Sameraaii, Ahmad

    2015-01-01

    Intoduction Ileal conduit stomal stenosis is a difficult complication to manage. Definitive treatment usually requires refashioning or a reconstruction of the conduit. There remains a need for minimally invasive procedures that can restore function to the stoma while avoiding the risks associated with a significant surgical procedure. This case illustrates a novel approach to the management of this complication. Presentation of case An 84 year old female with muscle-invasive bladder cancer underwent cystectomy with formation of an ileal conduit urinary diversion system. Her recovery was complicated by stomal stenosis leading to recurrent urinary tract infections. The Memokath Stent 045 is a thermo-expandable nickel–titanium stent designed for treatment of urethral strictures. The stent was inserted into the stoma under direct vision without the need for general anaesthesia or intraoperative radiography. The conduit remains patent 12 months after insertion and the metal stent showed no evidence of migration, calcification, oxidation or degradation. Discussion The use of a thermo-expandable nickel–titanium stent is able to provide the patency required to treat ileal conduit stomal stenosis. In this case, insertion of the stent was a simple procedure and no adverse events or degradation of the stent was identified at 12 months after insertion. The need for a significant surgical procedure such as a refashioning or reconstruction was avoided and general anaesthesia was not required to perform the procedure. Conclusion This case report highlights the possibility of using the thermo-expandable Memokath Stent 045 as an alternative to the long-term management of ileal conduit stomal stenosis. PMID:26745318

  7. Comparison of bare-metal and drug-eluting stents in patients with chronic kidney disease (from the NHLBI Dynamic Registry).

    PubMed

    Green, Sandy M; Selzer, Faith; Mulukutla, Suresh R; Tadajweski, Edward J; Green, Jamie A; Wilensky, Robert L; Laskey, Warren K; Cohen, Howard A; Rao, Sunil V; Weisbord, Steven D; Lee, Joon S; Reis, Steven E; Kip, Kevin E; Kelsey, Sheryl F; Williams, David O; Marroquin, Oscar C

    2011-12-01

    Patients with chronic kidney disease (CKD) have a disproportionate burden of coronary artery disease and commonly undergo revascularization. The role and safety of percutaneous coronary intervention (PCI) using drug-eluting stents (DESs) verses bare-metal stents in patients with CKD not on renal replacement therapy has not been fully evaluated. This study investigated the efficacy and safety of DES in patients with CKD not on renal replacement therapy. Patients were drawn from the National Heart, Lung, and Blood Institute Dynamic Registry and were stratified by renal function based on estimated glomerular filtration rate (GFR). Of the 4,157 participants, 1,108 had CKD ("low GFR" <60 ml/min/1.73 m(2)), whereas 3,049 patients had normal renal function ("normal GFR" ≥60 ml/min/1.73 m(2)). For each stratum of renal function we compared risk of death, myocardial infarction, or repeat revascularization between subjects who received DESs and bare-metal stents at the index procedure. Patients with low GFR had higher 1-year rates of death and myocardial infarction and a decreased rate of repeat revascularization compared to patients with normal GFR. Use of DESs was associated with a decreased need for repeat revascularization in the normal-GFR group (adjusted hazard ratio 0.63, 95% confidence interval 0.50 to 0.79, p <0.001) but not in the low-GFR group (hazard ratio 0.69, 95% confidence interval 0.45 to 1.06, p = 0.09). Risks of death and myocardial infarction were not different between the 2 stents in either patient population. In conclusion, presence of CKD predicted poor outcomes after PCI with high rates of mortality regardless of stent type. The effect of DES in decreasing repeat revascularization appeared to be attenuated in these patients.

  8. Coronary artery stents: evaluating new designs for contemporary percutaneous intervention.

    PubMed

    Kandzari, David E; Tcheng, James E; Zidar, James P

    2002-08-01

    Intracoronary stents have markedly improved the short- and long-term safety and efficacy of percutaneous coronary intervention by improving acute gains in luminal dimensions, decreasing abrupt vessel occlusion, and reducing restenosis. At present, nearly 90% of all coronary interventions involve stenting. A variety of advances in stent technology and design have expanded the clinical application of stenting to include complex coronary lesions, multivessel disease, and small-diameter vessels. In addition, the development of stents as drug delivery systems for antithrombotic or antiproliferative agents has the potential to expand the role of coronary stenting, and early clinical experience appears promising. The purpose of this review is to describe recent developments in stent design, examine the results of clinical trials of contemporary stents, and present future directions for investigation of new stent technologies. PMID:12124974

  9. 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

  10. The Development of Carotid Stent Material

    PubMed Central

    He, Dongsheng; Liu, Wenhua; Zhang, Tao

    2015-01-01

    Endovascular angioplasty with stenting is a promising option for treating carotid artery stenosis. There exist a rapidly increasing number of different stent types with different materials. The bare-metal stent is the most commonly used stent with acceptable results, but it leaves us with the problems of thrombosis and restenosis. The drug-eluting stent is a breakthrough as it has the ability to reduce the restenosis rate, but the problem of late thrombosis still has to be addressed. The biodegradable stent disappears after having served its function. However, restenosis and degradation rates remain to be studied. In this article, we review every stent material with its characteristics, clinical results and complications and point out the standards of an ideal carotid stent. PMID:26019710

  11. Safety and efficacy of a novel iopromide-based paclitaxel-eluting balloon following bare metal stent implantation in rabbit aorta abdominalis

    PubMed Central

    Zhu, Zhengbin; Han, Hui; Zhu, Jinzhou; Zhang, Jing; Du, Run; Ni, Jingwei; Ying, Chen; An, Xuanqi; Zhang, Ruiyan

    2015-01-01

    BACKGROUND: Drug-eluting balloons (DEB) may be promising technology for treating atherosclerotic arterial disease. In fact, several DEBs have been clinically available for the treatment of coronary in-stent restenosis (ISR), de novo coronary lesions, and peripheral artery disease. OBJECTIVE: We sought to elucidate the mechanism of action and in vivo safety and efficacy of a novel iopromide-based paclitaxel-eluting balloon. METHODS: In vitro cytotoxicity of a novel DEB on human umbilical vein endothelial cells (HUVECs) and in vivo pharmacokinetics of DEB in a rabbit aorta abdominalis were assessed. Then, bare metal stents (BMS) were implanted at both the proximal and distal sites of the rabbit aorta abdominalis. Stented vascular segments were immediately dilated with a bare balloon (control group) or the DEB (DEB group) randomly. Histological evaluation was performed in all treated segments at 28 days. Because paclitaxel is a tubulin-disrupting agent that binds preferentially to β-tubulin, we measured β-tubulin expression in aortal stent specimens via immunohistochemistry. RESULTS: We observed that DEB was compatible and could reduce neointimal hyperplasia compared with the bare balloon. Meanwhile, immunohistochemistry revealed that β-tubulin expression in the DEB group increased compared with the control group, indirectly suggesting successful uptake of paclitaxel by vessel walls after DEB dilation. CONCLUSIONS: The novel DEB is safe and has a favorable vascular healing response on neointimal hyperplasia. PMID:26484558

  12. 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.

  13. Diphenylalanine peptide nanotubes self-assembled on functionalized metal surfaces for potential application in drug-eluting stent.

    PubMed

    Zohrabi, Tayebeh; Habibi, Neda; Zarrabi, Ali; Fanaei, Maryam; Lee, Lai Yeng

    2016-09-01

    This study focuses on the potential of diphenylalanine self-assembled peptide nanotubes (FF Nts) for delivery of flufenamic acid (FA) from metal implants. Self-assembly of FF Nts was studied in solution and on surfaces of glass, silicone and gold substrates. FA was loaded inside the shell of FF Nts and subsequently FF/FA Nts were attached to gold surfaces. The substrate were characterized by Field Emission Scanning Electron Microscopy (FESEM), fluorescence microscopy, confocal microscopy, and UV-vis spectroscopy. Release of FA from FF Nts were investigated by immersing coated metal substrates in phosphate-buffered saline for 12 days. Self-assembly of FF in water and solvent resulted in formation of nanotubes, which efficiently loaded 98% of FA with concentration of 20 µg/mL. FESEM images confirmed successful attachment of FF/FA Nts to functionalized gold substrates. In vitro release studies indicated using FF Nts has prolonged the release rate of FA for several days. Biocompatibility studied confirmed more than 50% of the cells were alive in concentration of 250-1000 µg/mL of FF Nts thus suggesting the potential of peptide based self-assemble nanostructures as an alternate system for polymer coating in drugs eluting stents. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2280-2290, 2016.

  14. Flexibility and trackability of laser cut coronary stent systems.

    PubMed

    Szabadíts, Péter; Puskás, Zsolt; Dobránszky, János

    2009-01-01

    Coronary stents are the most important supports in present day cardiology. Flexibility and trackability are two basic features of stents. In this paper, four different balloon-expandable coronary stent systems were investigated mechanically in order to compare their suitability. The coronary stent systems were assessed by measurements of stent flexibility as well as by comparison of forces during simulated stenting in a self-investigated coronary vessel model. The stents were cut by laser from a single tube of 316L stainless steel or L-605 (CoCr) cobalt chromium alloy. The one-and four-point bending tests were carried out to evaluate the stent flexibility E x I (Nmm(2)), under displacement control in crimped and expanded configurations. The flexibility of stents would be rather dependent on the design than on raw material. In general a more flexible stent needs lower tracking force during the implantation. The L-605 raw material stents need lower track force to pass through in the vessel model than the 316L raw material stents. The sort and long stents passed through the curved vessel model in different ways. The long stents nestled to the vessel wall at the outer arc and bent, while the short stents did not bend in the curve, only the delivery systems bent.

  15. Therapies targeting inflammation after stent implantation.

    PubMed

    Okura, Hiroyuki; Takagi, Tsutomu; Yoshida, Kiyoshi

    2013-07-01

    Since the introduction of coronary vessel scaffold by metallic stent, percutaneous coronary intervention has become widely performed all over the world. Although drug-eluting stent technology has further decrease the incidence of in-stent restenosis, there still remaining issues related to stent implantation. Vessel inflammation is one of the causes that may be related to stent restenosis as well as stent thrombosis. Therefore, systemic therapies targeting inflammation emerged as adjunctive pharmacological intervention to improve outcome. Statins, corticosteroids, antiplatelets, and immunosuppresive or anti-cancer drugs are reported to favorably impact outcome after bare-metal stent implantation. In type 2 diabetic patients, pioglitazone may be the most promising drug that can lower neointimal proliferation and, as a result, lower incidence of restenosis and target lesion revascularization. On the other hand, several new stent platforms that might decrease inflammatory response after drug-eluting stent implantation have been introduced. Because durable polymer used in the first generation drug-eluting stents are recognized to be responsible for unfavorable vessel response, biocompatible or bioabsorbable polymer has been introduce and already used clinically. Furthermore, polymer-free drug-eluting stent and bioresorbable scaffold are under investigation. Although vessel inflammation may be reduced by using these new drug-eluting stents or scaffold, long-term impact needs to be investigated further. PMID:23905635

  16. 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

  17. Transtracheal single-point stent fixation in posttracheotomy tracheomalacia under cone-beam computer tomography guidance by transmural suturing with the Berci needle – a perspective on a new tool to avoid stent migration of Dumon stents

    PubMed Central

    Hohenforst-Schmidt, Wolfgang; Linsmeier, Bernd; Zarogoulidis, Paul; Freitag, Lutz; Darwiche, Kaid; Browning, Robert; Turner, J Francis; Huang, Haidong; Li, Qiang; Vogl, Thomas; Zarogoulidis, Konstantinos; Brachmann, Johannes; Rittger, Harald

    2015-01-01

    Tracheomalacia or tracheobronchomalacia (TM or TBM) is a common problem especially for elderly patients often unfit for surgical techniques. Several surgical or minimally invasive techniques have already been described. Stenting is one option but in general long-time stenting is accompanied by a high complication rate. Stent removal is more difficult in case of self-expandable nitinol stents or metallic stents in general in comparison to silicone stents. The main disadvantage of silicone stents in comparison to uncovered metallic stents is migration and plugging. We compared the operation time and in particular the duration of a sufficient Dumon stent fixation with different techniques in a patient with severe posttracheotomy TM and strongly reduced mobility of the vocal cords due to Parkinson’s disease. The combined approach with simultaneous Dumon stenting and endoluminal transtracheal externalized suture under cone-beam computer tomography guidance with the Berci needle was by far the fastest approach compared to a (not performed) surgical intervention, or even purely endoluminal suturing through the rigid bronchoscope. The duration of the endoluminal transtracheal externalized suture was between 5 minutes and 9 minutes with the Berci needle; the pure endoluminal approach needed 51 minutes. The alternative of tracheobronchoplasty was refused by the patient. In general, 180 minutes for this surgical approach is calculated. The costs of the different approaches are supposed to vary widely due to the fact that in Germany 1 minute in an operation room costs on average approximately 50–60€ inclusive of taxes. In our own hospital (tertiary level), it is nearly 30€ per minute in an operation room for a surgical approach. Calculating an additional 15 minutes for patient preparation and transfer to wake-up room, therefore a total duration inside the investigation room of 30 minutes, the cost per flexible bronchoscopy is per minute on average less than 6

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Engineering Stent Based Delivery System for Esophageal Cancer Using Docetaxel.

    PubMed

    Shaikh, Mohsin; Choudhury, Namita Roy; Knott, Robert; Garg, Sanjay

    2015-07-01

    Esophageal cancer patients are often diagnosed as "advanced" cases. These patients are subjected to palliative stenting using self-expanding metallic stents (SEMS) to maintain oral alimentation. Unfortunately, SEMS get reoccluded due to tumor growth, in and over the stent struts. To investigate potential solutions to this problem, docetaxel (DTX) delivery films were prepared using PurSil AL 20 (PUS), which can be used as a covering material for the SEMS. Drug-polymer miscibility and interactions were studied. Bilayer films were prepared by adhering the blank film to the DTX loaded film in order to maintain the unidirectional delivery to the esophagus. In vitro release and the local DTX delivery were studied using in vitro permeation experiments. It was found that DTX and PUS were physically and chemically compatible. The bilayer films exhibited sustained release (>30 days) and minimal DTX permeation through esophageal tissues in vitro. The rate-determining step for the DTX delivery was calculated. It was found that >0.9 fraction of rate control lies with the esophageal tissues, suggesting that DTX delivery can be sustained for longer periods compared to the in vitro release observed. Thus, the bilayer films can be developed as a localized sustained delivery system in combination with the stent.

  3. 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

  4. 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.

  5. Paclitaxel Drug-Eluting Stents in Peripheral Arterial Disease: A Health Technology Assessment

    PubMed Central

    2015-01-01

    Background Peripheral arterial disease is a condition in which atherosclerotic plaques partially or completely block blood flow to the legs. Although percutaneous transluminal angioplasty and metallic stenting have high immediate success rates in treating peripheral arterial disease, long-term patency and restenosis rates in long and complex lesions remain unsatisfactory. Objective The objective of this analysis was to evaluate the clinical effectiveness, safety, cost-effectiveness and budget impact of Zilver paclitaxel self-expanding drug-eluting stents for the treatment of de novo or restenotic lesions in above-the-knee peripheral arterial disease. Data Sources Literature searches were performed using Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid Embase, EBSCO Cumulative Index to Nursing & Allied Health Literature (CINAHL), and EBM Reviews. For the economic review, a search filter was applied to limit search results to economics-related literature. Data sources for the budget impact analysis included expert opinion, published literature, and Ontario administrative data. Review Methods Systematic reviews, meta-analyses, randomized controlled trials, and observational studies were included in the clinical effectiveness review, and full economic evaluations were included in the economic literature review. Studies were included if they examined the effect of Zilver paclitaxel drug-eluting stents in de novo or restenotic lesions in above-the-knee arteries. For the budget impact analysis, 3 scenarios were constructed based on different assumptions. Results One randomized controlled trial reported a significantly higher patency rate with Zilver paclitaxel drug-eluting stents for lesions ≤ 14 cm than with angioplasty or bare metal stents. One observational study showed no difference in patency rates between Zilver paclitaxel drug-eluting stents and paclitaxel drug-coated balloons. Zilver paclitaxel drug-eluting stents were associated with

  6. 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

  7. Sequential Stenting for Extensive Malignant Airway Stenosis

    PubMed Central

    Takahama, Makoto; Nakajima, Ryu; Kimura, Michitaka; Tei, Keiko; Yamamoto, Ryoji

    2014-01-01

    Purpose: Malignant airway stenosis extending from the bronchial bifurcation to the lower lobar orifice was treated with airway stenting. We herein examine the effectiveness of airway stenting for extensive malignant airway stenosis. Methods: Twelve patients with extensive malignant airway stenosis underwent placement of a silicone Dumon Y stent (Novatech, La Ciotat, France) at the tracheal bifurcation and a metallic Spiral Z-stent (Medico’s Hirata, Osaka, Japan) at either distal side of the Y stent. We retrospectively analyzed the therapeutic efficacy of the sequential placement of these silicone and metallic stents in these 12 patients. Results: The primary disease was lung cancer in eight patients, breast cancer in two patients, tracheal cancer in one patient, and thyroid cancer in one patient. The median survival period after airway stent placement was 46 days. The Hugh–Jones classification and performance status improved in nine patients after airway stenting. One patient had prolonged hemoptysis and died of respiratory tract hemorrhage 15 days after the treatment. Conclusion: Because the initial disease was advanced and aggressive, the prognosis after sequential airway stent placement was significantly poor. However, because respiratory distress decreased after the treatment in most patients, this treatment may be acceptable for selected patients with extensive malignant airway stenosis. PMID:25273272

  8. Correlation between the ultimate elongations of rapidly expanding rings and stretching metal jets

    SciTech Connect

    Gourdin, W.H.

    1990-08-01

    The recent work of Duffy and Golaski and Lichtenberger demonstrated that the initial metallurgical condition of a material can significantly affect its performance when used as a shaped-charge liner. Duffy and Golaski showed that the penetration of copper shaped charges increases by 10--20% when the grain size of the liner is reduced from 150 to 25 {mu}m and the uniformity of the microstructure is improved. Lichtenberger confirmed this behavior in liners made from oxygen-free electronic (OFE) grade copper and also showed that the purity of the liner material can produce similar effects. These observations suggest that some characteristic of the liner material itself can be correlated with shaped-charge performance. Such a characteristic, along with a corresponding laboratory test procedure, would be very useful as a means of identifying promising candidate materials prior to the expensive testing of prototype munitions. Lichtenberger has suggested that the recrystallization temperature'' is one such characteristic, and he has successfully demonstrated a correlation with jet behavior. In this paper, I suggest that the ultimate elongation of specimen rings expanded by means of the electromagnetic launch technique is another material characteristic that appears to correlate with the breakup behavior of stretching metal jets. I briefly discuss in general terms why such a correlation may exist and then offer some limited experimental evidence for it.

  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. 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

  11. 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

  12. 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.

  13. Colonic perforation after stent placement for malignant colorectal obstruction--causes and contributing factors.

    PubMed

    Datye, Arundhati; Hersh, Jeff

    2011-05-01

    Self-expanding metal stents (SEMS) are used to manage malignant colorectal obstruction. Colonic perforation is the most worrisome complication from colonic stenting. We reviewed causes and contributing factors of perforation with colonic stent placement in patients with malignant colorectal obstruction. Articles from both English and foreign language publications were identified from Medline. Data were collected on causes, timing, treatment and mortality related to perforation. A total of 2287 patients from 82 articles were included in this analysis, which showed an overall perforation rate of 4.9%. Perforation rates for palliation and bridge to surgery (BTS) were not significantly different (4.8% vs. 5.4%, p = 0.66); over 80% occurred within 30 days of stent placement (half during or within one day of the procedure). The mortality rate related to perforation was 0.8% per stented patient, but the mortality of patients experiencing perforation was 16.2%. There was no significant difference (p = 0.78) in the mortality rates between the palliation and the BTS group and concomitant chemotherapy, steroids, and radiotherapy are risk factors of perforation. The overall perforation related mortality is far less than that of patients undergoing emergency surgery for bowel obstruction. PMID:20929424

  14. 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

  15. Targeting In-Stent-Stenosis with RGD- and CXCL1-Coated Mini-Stents in Mice.

    PubMed

    Simsekyilmaz, Sakine; Liehn, Elisa A; 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.

  16. Esophageal Stent for Refractory Variceal Bleeding: A Systemic Review and Meta-Analysis

    PubMed Central

    Guo, Xiao-Zhong

    2016-01-01

    Background. Preliminary studies suggest that covered self-expandable metal stents may be helpful in controlling esophageal variceal bleeding. Aims. To evaluate the effectiveness and safety of esophageal stent in refractory variceal bleeding in a systematic review and meta-analysis. Methods. A comprehensive literature search was conducted on PubMed, EMBASE, and Cochrane Library covering the period from January 1970 to December 2015. Data were selected and abstracted from eligible studies and were pooled using a random-effects model. Heterogeneity was assessed using I2 test. Results. Five studies involving 80 patients were included in the analysis. The age of patients ranged from 18 to 91 years. The mean duration of follow-up was 46.8 d (range, 30–60 d). The success rate of stent deployment was 96.7% (95% CI: 91.6%–99.5%) and complete response to esophageal stenting was in 93.9% (95% CI: 82.2%–99.6%). The incidence of rebleeding was 13.2% (95% CI: 1.8%–32.8%) and the overall mortality was 34.5% (95% CI: 24.8%–44.8%). Most of patients (87.4%) died from hepatic or multiple organ failure, and only 12.6% of patients died from uncontrolled bleeding. There was no stent-related complication reported and the incidence of stent migration was 21.6% (95% CI: 4.7%–46.1%). Conclusion. Esophageal stent may be considered in patients with variceal bleeding refractory to conventional therapy. PMID:27517043

  17. Longitudinal stent deformation during coronary bifurcation stenting.

    PubMed

    Vijayvergiya, Rajesh; Sharma, Prafull; Gupta, Ankush; Goyal, Praveg; Panda, Prashant

    2016-03-01

    A distortion of implanted coronary stent along its longitudinal axis during coronary intervention is known as longitudinal stent deformation (LSD). LSD is frequently seen with newer drug eluting stents (DES), specifically with PROMUS Element stent. It is usually caused by impact of guide catheter tip, or following passage of catheters like balloon catheter, IVUS catheter, guideliner, etc. We hereby report a case of LSD during coronary bifurcation lesion intervention, using two-stents technique. Patient had acute stent thrombosis as a complication of LSD, which was successfully managed. PMID:26811144

  18. 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.

  19. Endoluminal stenting of obstructed colorectal tumours.

    PubMed Central

    Boorman, P.; Soonawalla, Z.; Sathananthan, N.; MacFarlane, P.; Parker, M. C.

    1999-01-01

    A series of patients were selected to evaluate the clinical efficacy of a new self expanding metallic endoprosthesis in the management of left-sided colonic obstruction. The aim was to reduce the morbidity and mortality associated with the surgical management of patients with distal colonic obstruction. Six patients with complete sigmoid colon obstruction were managed with the Wallstent Enteral Endoprosthesis [Schneider (USA) Inc.]. Four underwent subsequent elective colonic resection, while two were placed for palliation. Stent placement was successful in all cases with resulting bowel decompression and there were no procedural complications. All four patients with resectable tumours avoided emergency surgery. Stenting allowed time for medical improvement and staging investigations in this group. Two patients with advanced metastatic colonic carcinoma were successfully palliated. We found the Wallstent Enteral Endoprosthesis to be safe and effective in relieving obstruction in patients with resectable colonic tumours, permitting elective surgery and avoiding a temporary stoma. It can also be used to palliate those patients with advanced disease. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:10615192

  20. [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.

  1. Esophageal stenting for benign and malignant disease: European Society of Gastrointestinal Endoscopy (ESGE) Clinical Guideline.

    PubMed

    Spaander, Manon C W; Baron, Todd H; Siersema, Peter D; Fuccio, Lorenzo; Schumacher, Brigitte; Escorsell, Àngels; Garcia-Pagán, Juan-Carlos; Dumonceau, Jean-Marc; Conio, Massimo; de Ceglie, Antonella; Skowronek, Janusz; Nordsmark, Marianne; Seufferlein, Thomas; Van Gossum, André; Hassan, Cesare; Repici, Alessandro; Bruno, Marco J

    2016-10-01

    This Guideline is an official statement of the European Society of Gastrointestinal Endoscopy (ESGE), endorsed by the European Society for Radiotherapy and Oncology (ESTRO), the European Society of Digestive Endoscopy (ESDO), and the European Society for Clinical Nutrition and Metabolism (ESPEN). 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 for malignant disease 1 ESGE recommends placement of partially or fully covered self-expandable metal stents (SEMSs) for palliative treatment of malignant dysphagia over laser therapy, photodynamic therapy, and esophageal bypass (strong recommendation, high quality evidence). 2 For patients with longer life expectancy, ESGE recommends brachytherapy as a valid alternative or in addition to stenting in esophageal cancer patients with malignant dysphagia. Brachytherapy may provide a survival advantage and possibly a better quality of life compared to SEMS placement alone. (Strong recommendation, high quality evidence.) 3 ESGE recommends esophageal SEMS placement as the preferred treatment for sealing malignant tracheoesophageal or bronchoesophageal fistula (strong recommendation, low quality evidence). 4 ESGE does not recommend the use of concurrent external radiotherapy and esophageal stent treatment. SEMS placement is also not recommended as a bridge to surgery or prior to preoperative chemoradiotherapy. It is associated with a high incidence of adverse events and alternative satisfactory options such as placement of a feeding tube are available. (Strong recommendation, low quality evidence.) Main recommendations for benign disease 1 ESGE recommends against the use of self-expandable stents (SEMSs) as first-line therapy for the management of benign esophageal strictures because of the potential for adverse events, the availability of alternative therapies, and costs (strong

  2. Percutaneous coronary angioscopy and stents

    NASA Astrophysics Data System (ADS)

    Heuser, Richard R.

    1994-05-01

    With the expanding array of therapies available for coronary intervention, the invasive cardiologist has many choices for treating a specific lesion in an individual patient. Certain types of lesions might respond more effectively with stents, particularly the rigid Palmax- Schatz device. Thrombus and dissection immediately following stent placement are associated with early occlusion, and the interventionist must be able to assess their presence pre- and post-stenting. Angiography is deficient in quantifying minimal disease and in defining lesion architecture and composition, as well as the plaque rupture and thrombosis associated with unstable angina. It is also imprecise in detecting dissection and thrombus. Intravascular ultrasound (IVUS) provides high-resolution images that delineate irregularities and other structures inside the lumen and within the vessel wall and surrounding tissues. Like angiography, IVUS has limited specificity for thrombus differentiation. Angioscopy is superior to angiography and IVUS in detecting thrombus and dissection. Angioscopy allows the clinician to assess the appearance of stent struts after deployment and at follow-up. This may aid in reducing acute complications as well as restenosis. Follow-up angioscopy of stents to detect thrombus or exposed struts may guide therapy in a patient who has clinical symptoms of restenosis.

  3. Plasma pentraxin 3 may be a more sensitive marker of inflammatory response than high-sensitivity C-reactive protein after bare-metal stent compared to drug-eluting stent implantation.

    PubMed

    Hudzik, Bartosz; Szkodzinski, Janusz; Pietka-Rzycka, Anna; Danikiewicz, Aleksander; Wojnar, Rafal; Lekston, Andrzej; Polonski, Lech; Zubelewicz-Szkodzinska, Barbara

    2013-05-01

    C-reactive protein (CRP) and pentraxin 3 (PTX3) are members of a highly conserved pentraxin superfamily. CRP is synthesized in the liver and may represent a systemic response to local inflammation. PTX3 is synthesized locally at the inflammatory sites and may represent a marker for local inflammation at sites of vessel injury. We compared plasma high-sensitivity CRP (hsCRP) and PTX3 concentrations after bare-metal stent (BMS) and drug-eluting stent (DES) implantation. Fifty-three patients with stable coronary artery disease who underwent percutaneous coronary intervention were divided into 2 groups: 1-24 patients (BMS group) and 2-29 patients (DES group). Patients were scheduled for an elective, 6-month clinical follow-up. Major adverse cardiovascular events (MACEs) (death, myocardial infarction, target vessel revascularization) were assessed. Baseline clinical characteristics were similar in both groups. Patients after BMS implantation had a higher median PTX3 concentration 1.02 ng/mL compared to patients after DES implantation 0.80 ng/mL, P=0.045. Median hsCRP concentrations were similar in both groups: 0.9 mg/L versus 0.89 mg/L, respectively. Six-month follow-up was available in 33 patients. Four out of 33 patients had MACEs during follow-up. The cut-off value to predict MACEs for PTX3 was >1.16 ng/mL (P=0.004) and for hsCRP was >0.95 mg/L (P<0.001). Patients after DES implantation showed significantly lower plasma PTX3 levels compared with patients after BMS implantation. hsCRP showed no difference between the study groups. PTX3 may be a more sensitive marker of local inflammatory response due to vessel injury by BMS than hsCRP. DES implantation may attenuate the early inflammatory response. Lower PTX3 levels may reflect potent anti-inflammatory properties of DES.

  4. Biodegradable esophageal stents in benign and malignant strictures – a single center experience

    PubMed Central

    Sigounas, Dimitrios E.; Siddhi, Sandeep; Plevris, John N.

    2016-01-01

    Background and study aims: Biodegradable (BD) esophageal stents were recently developed mainly for refractory benign strictures, but experience and available literature are limited. Patients and methods: This was a retrospective observational study. All patients who had BD stents inserted due to refractory benign esophageal strictures or malignant strictures, or were awaiting radical radiotherapy/chemotherapy or neo-adjuvant therapy and esophagectomy between March 2011 and July 2015 were included. Results: Stent placement was successful in all patients. Ten patients with benign strictures (3 male, median age 80.5 years, IQR: 68.75 – 89.5) were followed-up for a median of 171.5 weeks (IQR: 24 – 177.25). The interval between dilatations prior to the first BD stent placement (median: 34.25 days, IQR: 23.06 – 48.29) was significantly shorter than the interval between the first BD stent placement and the first intervention required (median: 149.5 days, IQR: 94.25 – 209.5) and this difference was statistically significant (P = 0.012). Ten patients with esophageal cancer (8 male, median age: 69 years, IQR: 59.25 – 80.75) were included and they were followed up for a median of 36 weeks (IQR: 26 – 58). Only 1 completed radical radiotherapy successfully, but developed refractory post-radiotherapy stricture. No one proceeded to esophagectomy and 50 % required a self-expanding metal stent (SEMS) at a median of 134 days (IQR: 100 – 263) following stent placement. Conclusions: BD stents were successfully deployed in both benign and malignant strictures. They offered a prolonged dilatation-free interval in benign strictures, yet in the majority of patients, strictures recurred. In malignant strictures, stent patency was similar to that of benign strictures, which suggests a potential value in ensuring adequate oral intake during oncologic therapy. In our cohort, however, use of stents did not contribute to improved outcome. PMID

  5. 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.

    2016-09-01

    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.

  6. Recanalization Results After Intracranial Stenting of Atherosclerotic Stenoses

    SciTech Connect

    Blasel, Stella Yuekzek, Zeynep; Kurre, Wiebke; Berkefeld, Joachim; Neumann-Haefelin, Tobias; Hattingen, Elke; Mesnil de Rochemont, Richard du

    2010-10-15

    The purpose of this investigation was to provide a detailed description of the angiographic results after stenting of high-grade intracranial stenosis using balloon-expandable stents. Forty consecutive patients with symptomatic atherosclerotic intracranial stenosis >50% received endovascular treatment by placement of balloon-expandable stents using the concept of slight underdilation and strict avoidance of overdilation. Intra-arterial digital subtraction angiography images before and after stenting in the same projection were reviewed for pre- and post-therapeutic measurement of the degree of stenosis and evaluation of morphologic criteria like plaque coverage, stent apposition, patency of side branches, and signs of dissection or vasospasm. Stenting decreased the mean percentage stenosis from 76.2 (WASID criteria) to 20.8%. Residual stenosis ranged from 0 to 55% with residual stenosis >50% in two of 40 cases. Technical success rate was 95%. There were no major vessel complications, but minor abnormalities like incomplete stent apposition (8/40) or plaque coverage (7/40), incomplete filling of side branches (13/40), and minor dissections after stenting (2/40) were seen. One case with incomplete stent apposition and two cases with side branch compromise were associated with clinical symptoms. In conclusion, intracranial stenting with slight underdilation avoided major vessel complication and created reliable luminal gain. Suboptimal recanalization results were frequently detected and may be the source of neurological complications in individual cases.

  7. Transition-Metal-Mediated Release of Nitric Oxide (NO) from S-Nitroso-N-acetyl-d-penicillamine (SNAP): Potential Applications for Endogenous Release of NO at the Surface of Stents Via Corrosion Products.

    PubMed

    McCarthy, Connor W; Guillory, Roger J; Goldman, Jeremy; Frost, Megan C

    2016-04-27

    Nitric oxide (NO), identified over the last several decades in many physiological processes and pathways as both a beneficial and detrimental signaling molecule, has been the subject of extensive research. Physiologically, NO is transported by a class of donors known as S-nitrosothiols. Both endogenous and synthetic S-nitrosothiols have been reported to release NO during interactions with certain transition metals, primarily Cu(2+) and Fe(2+). Ag(+) and Hg(2+) have also been identified, although these metals are not abundantly present in physiological systems. Here, we evaluate Pt(2+), Fe(2+), Fe(3+), Mg(2+), Zn(2+), Mn(2+), Co(2+), Ni(2+), and Cu(2+) for their ability to generate NO from S-nitroso-N-acetyl-d-penicillamine (SNAP) under physiological pH conditions. Specifically, we report NO generation from RSNOs initiated by three transition metal ions; Co(2+), Ni(2+), and Zn(2+), which have not been previously reported to generate NO. Additionally, preliminary in vivo evidence of zinc wires implanted in the rat arterial wall and circulating blood is presented which demonstrated inhibited thrombus formation after 6 months. One potentially useful application of these metal ions capable of generating NO from RSNOs is their use in the fabrication of biodegradable metallic stents capable of generating NO at the stent-blood interface, thereby reducing stent-related thrombosis and restenosis.

  8. Measurement and Comparison of Mechanical Properties of Nitinol Stents

    NASA Astrophysics Data System (ADS)

    Hanus, Josef; Zahora, Jiri

    2005-01-01

    The self expandable Nitinol stents or stentgrafts are typically used for miniinvasive treatment of stenosis and aneurysms in the cardiovascular system. The minimal traumatisation of the patient, shorter time of hospitalization are typical advantages of these methods. More than ten years of experience has yielded also important information about the performance of stents in interaction with biological system and the possible problems related with it. The leakage or the shift of stent are some typical disadvantages, that can be related among other in the construction of the stent. The problem is that the mechanical properties, dimensions and the dynamical properties of the stent do not exactly correspond to the properties of the vessel or generally of tissue where this stent is introduced. The measurement, the description and the comparison of the relations between the mechanical properties of stents and tissues can be one of the possible ways to minimize these disadvantages. The developed original computer controlled measuring system allows the measurement of mechanical properties of stents, the measurement of strain-stress curves or simulation of interaction of the stent and vessel for exactly defined hemodynamic conditions. We measured and compared the mechanical parameters of different selfexpandable Nitinol stents, which differed in geometry (radius and length), in the type of construction (number of branches and rising of winding) and in the diameter of used wire. The results of measurements confirmed the theoretical assumptions that just the diameter of the Nitinol wire significantly influences the rigidity and the level of compressibility of the stent as well. A compromise must be found between the required rigidity of the stent and the minimal size of the delivery system. The exact description of the relation between the mechanical properties and geometry and construction of the stents enables to design the stent to fit the patient and it is expected that

  9. 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.

  10. Fast Virtual Stenting with Active Contour Models in Intracranical Aneurysm.

    PubMed

    Zhong, Jingru; Long, Yunling; Yan, Huagang; Meng, Qianqian; Zhao, Jing; Zhang, Ying; Yang, Xinjian; Li, Haiyun

    2016-02-15

    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.

  11. 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

  12. 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. PMID:10816295

  13. Evaluation of safety and efficacy of NexGen – an ultrathin strut and hybrid cell design cobalt-chromium bare metal stent implanted in a real life patient population – the Polish NexGen Registry

    PubMed Central

    Milewski, Krzysztof; Gąsior, Paweł; Samborski, Stefan; Buszman, Piotr P.; Błachut, Aleksandra; Młodziankowski, Adam; Mendyk, Artur; Król, Marek; Wojakowski, Wojciech; Buszman, Paweł E.

    2016-01-01

    Introduction Despite the dominance of drug-eluting stents in modern interventional cardiology, there is still a niche for bare metal stents. Aim The aim of the Polish NexGen registry was to evaluate the safety and efficacy of a new generation cobalt-chromium NexGen stent in a real life patient population. Material and methods A prospective multi-center registry was conducted in five clinical sites of American Heart of Poland. Three hundred and eighty-three patients who underwent percutaneous coronary intervention (PCI) with NexGen stent implantation were included. Clinical follow-up was performed at 1, 6 and 12 months. Additionally, a group of 42 randomly selected patients underwent control angiography at 6 months (10.96% of study population). The primary endpoint was occurrence of target vessel revascularization (TVR) at 6-month follow-up. Angiographic endpoints included rates of binary restenosis and late lumen loss at 6-month follow-up based on QCA analysis. Multivessel disease was present in more than 70% of patients, and 52.4% of lesions were complex. The main indications for angiography were non-ST elevation acute coronary syndromes (54.8%) and ST elevation myocardial infarction (34.99%). Results At 6-month follow-up 47 (12.7%) patients reached the primary endpoint of TVR. The composite of major acute cardiac event rates at 30-day and 6- and 12-month follow-up was 6.01% (n = 23), 18.5% (n = 69) and 25.21% (n = 92) respectively. Control angiography performed after 6 months showed in-stent late loss of 0.66 ±0.71 mm and a binary restenosis rate of 16.7%. Conclusions Our study showed that PCI with the NexGen stent is safe and effective at 6- and 12-month follow-up. Angiographic results showed a satisfactory restenosis rate and low late lumen loss. PMID:27625684

  14. Evaluation of safety and efficacy of NexGen – an ultrathin strut and hybrid cell design cobalt-chromium bare metal stent implanted in a real life patient population – the Polish NexGen Registry

    PubMed Central

    Milewski, Krzysztof; Gąsior, Paweł; Samborski, Stefan; Buszman, Piotr P.; Błachut, Aleksandra; Młodziankowski, Adam; Mendyk, Artur; Król, Marek; Wojakowski, Wojciech; Buszman, Paweł E.

    2016-01-01

    Introduction Despite the dominance of drug-eluting stents in modern interventional cardiology, there is still a niche for bare metal stents. Aim The aim of the Polish NexGen registry was to evaluate the safety and efficacy of a new generation cobalt-chromium NexGen stent in a real life patient population. Material and methods A prospective multi-center registry was conducted in five clinical sites of American Heart of Poland. Three hundred and eighty-three patients who underwent percutaneous coronary intervention (PCI) with NexGen stent implantation were included. Clinical follow-up was performed at 1, 6 and 12 months. Additionally, a group of 42 randomly selected patients underwent control angiography at 6 months (10.96% of study population). The primary endpoint was occurrence of target vessel revascularization (TVR) at 6-month follow-up. Angiographic endpoints included rates of binary restenosis and late lumen loss at 6-month follow-up based on QCA analysis. Multivessel disease was present in more than 70% of patients, and 52.4% of lesions were complex. The main indications for angiography were non-ST elevation acute coronary syndromes (54.8%) and ST elevation myocardial infarction (34.99%). Results At 6-month follow-up 47 (12.7%) patients reached the primary endpoint of TVR. The composite of major acute cardiac event rates at 30-day and 6- and 12-month follow-up was 6.01% (n = 23), 18.5% (n = 69) and 25.21% (n = 92) respectively. Control angiography performed after 6 months showed in-stent late loss of 0.66 ±0.71 mm and a binary restenosis rate of 16.7%. Conclusions Our study showed that PCI with the NexGen stent is safe and effective at 6- and 12-month follow-up. Angiographic results showed a satisfactory restenosis rate and low late lumen loss.

  15. Stent migration during transcatheter management of coarctation of aorta.

    PubMed

    Kannan, Bhava R J; Srinivasan, Muthusamy

    2012-02-15

    A 13-year-old girl underwent endovascular stent placement for coarctation of aorta. The fully expanded stent migrated to ascending aorta which could be stabilized, recrimped, and repositioned with a 20-mm goose neck snare. Postdilatation was performed from the left brachial route resulting in a good outcome.

  16. Indications for stenting during thrombolysis.

    PubMed

    Bækgaard, N; Broholm, R; Just, S

    2013-03-01

    The most important vein segment to thrombolyse after deep venous thrombosis (DVT) is the outflow tract meaning the iliofemoral vein. Iliofemoral DVT is defined as DVT in the iliac vein and the common femoral vein. Spontaneous recanalization is less than 50%, particularly on the left side. The compression from adjacent structures, predominantly on the left side is known as the iliac vein compression syndrome. Therefore, it is essential that supplementary endovenous procedures have to be performed in case of persistent obstructive lesions following catheter-directed thrombolysis. Insertion of a stent in this position is the treatment of choice facilitating the venous flow into an unobstructed outflow tract either from the femoral vein or the deep femoral vein or both. The stent, made of stainless steel or nitinol, has to be self-expandable and flexible with radial force to overcome the challenges in this low-pressure system. The characteristics of the anatomy with external compression and often a curved vein segment with diameter difference make stent placement necessary. Ballooning alone has no place in this area. The proportion of inserted stents varies in the published materials with catheter-directed thrombolysis of iliofemoral deep venous thrombosis. PMID:23482545

  17. Chemical etching of nitinol stents.

    PubMed

    Katona, Bálint; Bognár, Eszter; Berta, Balázs; Nagy, Péter; Hirschberg, Kristóf

    2013-01-01

    At present the main cause of death originates from cardiovascular diseases. Primarily the most frequent cause is vessel closing thus resulting in tissue damage. The stent can help to avoid this. It expands the narrowed vessel section and allows free blood flow. The good surface quality of stents is important. It also must have adequate mechanical characteristics or else it can be damaged which can easily lead to the fracture of the implant. Thus, we have to consider the importance of the surface treatment of these implants. In our experiments the appropriate design was cut from a 1.041 mm inner diameter and 0.100 mm wall thickness nitinol tube by using Nd:YAG laser device. Then, the stent was subjected to chemical etching. By doing so, the burr created during the laser cutting process can be removed and the surface quality refined. In our research, we changed the time of chemical etching and monitored the effects of this parameter. The differently etched stents were subjected to microscopic analysis, mass measurement and in vivo environment tests. The etching times that gave suitable surface and mechanical features were identified.

  18. The Supralimus sirolimus-eluting stent.

    PubMed

    Lemos, Pedro A; Bienert, Igor

    2013-05-01

    The use of biodegradable polymeric coatings has emerged as a potential bioengineering target to improve the vascular compatibility of coronary drug-eluting stents (DESs). This review summarizes the main features and scientific facts about the Supralimus sirolimus-eluting stent (Sahajanand Medical Technologies Ltd, Surat, India), which is a biodegradable polymer-based, sirolimus-eluting metallic stent that was recently introduced for routine use in Europe. The novel stent is built on a stainless steel platform, coated with a blend of biodegradable polymers (poly-l-lactide, poly-dl-lactide-co-glycolide and polyvinyl pyrrolidone; coating thickness is 4-5 µm). The active agent is the antiproliferative sirolimus in a dose load of 1.4 µg/mm(2), which is released within 48 days. The Supralimus stent was initially evaluated in the single-arm SERIES-I study, which showed binary angiographic restenosis rates of 0% (in-stent) and 1.7% (in-segment) and an in-stent late lumen loss of 0.09 ± 0.28 mm. The multicenter randomized PAINT trial compared two DESs with identical metallic platforms and biodegradable polymer carriers, but different agents (Infinnium [Sahajanand Medical Technologies Pvt Ltd] paclitaxel-eluting stent or Supralimus sirolimus-eluting stent) against bare stents. After 3 years, the pooled DES population had similar rates of cardiac death or myocardial infarction (9 vs 7.1%; p = 0.6), but a lower risk of repeat interventions (10 vs 29.9%; p < 0.01) than controls with bare stents. The incidence of definite or probable stent thrombosis in the pooled DES group was 2.3% (1st year: 1.8%; 2nd year: 0.4% and 3rd year: 0%). These results demonstrate that the novel Supralimus stents are effective in reducing reintervention, while potentially improving the safety profile by decreasing the risk of late-term thrombosis, even though further studies would be necessary to confirm these findings.

  19. The Supralimus sirolimus-eluting stent.

    PubMed

    Lemos, Pedro A; Bienert, Igor

    2013-05-01

    The use of biodegradable polymeric coatings has emerged as a potential bioengineering target to improve the vascular compatibility of coronary drug-eluting stents (DESs). This review summarizes the main features and scientific facts about the Supralimus sirolimus-eluting stent (Sahajanand Medical Technologies Ltd, Surat, India), which is a biodegradable polymer-based, sirolimus-eluting metallic stent that was recently introduced for routine use in Europe. The novel stent is built on a stainless steel platform, coated with a blend of biodegradable polymers (poly-l-lactide, poly-dl-lactide-co-glycolide and polyvinyl pyrrolidone; coating thickness is 4-5 µm). The active agent is the antiproliferative sirolimus in a dose load of 1.4 µg/mm(2), which is released within 48 days. The Supralimus stent was initially evaluated in the single-arm SERIES-I study, which showed binary angiographic restenosis rates of 0% (in-stent) and 1.7% (in-segment) and an in-stent late lumen loss of 0.09 ± 0.28 mm. The multicenter randomized PAINT trial compared two DESs with identical metallic platforms and biodegradable polymer carriers, but different agents (Infinnium [Sahajanand Medical Technologies Pvt Ltd] paclitaxel-eluting stent or Supralimus sirolimus-eluting stent) against bare stents. After 3 years, the pooled DES population had similar rates of cardiac death or myocardial infarction (9 vs 7.1%; p = 0.6), but a lower risk of repeat interventions (10 vs 29.9%; p < 0.01) than controls with bare stents. The incidence of definite or probable stent thrombosis in the pooled DES group was 2.3% (1st year: 1.8%; 2nd year: 0.4% and 3rd year: 0%). These results demonstrate that the novel Supralimus stents are effective in reducing reintervention, while potentially improving the safety profile by decreasing the risk of late-term thrombosis, even though further studies would be necessary to confirm these findings. PMID:23597097

  20. A method for investigating the mechanical properties of intracoronary stents using finite element numerical simulation.

    PubMed

    Tan, L B; Webb, D C; Kormi, K; Al-Hassani, S T

    2001-03-01

    The proliferation of stent designs poses difficult problems to clinicians, who have to learn the relative merits of all stents to ensure optimal selection for each lesion, and also to regulatory authorities who have the dilemma of preventing the inappropriate marketing of substandard stents while not denying patients the benefits of advanced technology. Of the major factors influencing long-term results, those of patency and restenosis are being actively studied whereas the mechanical characteristics of devices influencing the technical results of stenting remain under-investigated. Each different stent design has its own particular features. A robust method for the independent objective comparison of the mechanical performance of each design is required. To do this by experimental measurement alone may be prohibitively expensive. A less costly option is to combine computer analysis, employing the standard numerical technique of the finite element method (FEM), with targeted experimental measurements of the specific mechanical behaviour of stents. In this paper the FEM technique is used to investigate the structural behaviour of two different stent geometries: Freedom stent geometry and Palmaz-Schatz (P-S) stent geometry. The effects of altering the stent geometry, the stent wire diameter and contact with (and material properties of) a hard eccentric intravascular lesion (simulating a calcified plaque) on stent mechanical performance were investigated. Increasing the wire diameter and the arterial elastic modulus by 150% results in the need to increase the balloon pressure to expand the stent by 10-fold. Increasing the number of circumferential convolutions increases the pressure required to initiate radial expansion of mounted stents. An incompressible plaque impinging on the mid portion of a stent causes a gross distortion of the Freedom stent and an hour-glass deformity in the P-S stent. These findings are of relevance for future comparative studies of the

  1. Intracranial Stenting in the Treatment of Wide-Necked Aneurysms

    PubMed Central

    Leonardi, M.; Dall'olio, M.; Cenni, P.; Raffi, L.; Simonetti, L.

    2007-01-01

    Summary We positioned the following self-expanding stents certified for intracranial application: 16 Neuro form (Boston Scientific), three INX (Medtronic), one Leo (Balt). 6F calibre femoral introducers and guiding catheters were used for stent placement changing to 5F calibre introducers and guiding catheters (Envoy, Cordis) for the Neuroform 2 and 3 stents. All procedures were carried out under general anaesthesia and heparinization. Our pharmacological protocol consisted of adjunctive treatment with anti-aggregants during the interventional procedure and for the following six months, without premedication. From November 2000 to August 2006 we treated 28 patients (27 F/1M) with giant wide-necked aneurysms and one dissecting basilar artery aneurysm requiring the placement of 29 stents. We successfully positioned 20 stents: 11 stents combined with coils (8 immediate; 3 late) with complete exclusion of the aneurysm from the circulation in seven cases and subtotal exclusion in four; nine stents not followed by embolization with complete exclusion of the aneurysm from the circulation in six cases and subtotal exclusion in three. Stenting was not possible in nine cases due to extreme vessel tortuosity and the poor flexibility of release systems for the first stents. No late stent occlusion or subarachnoid haemorrhage were encountered after treatment. PMID:20566126

  2. New approach to quantitative angiographic assessment after stent implantation.

    PubMed

    Reimers, B; Di Mario, C; Di Francesco, L; Moussa, I; Blengino, S; Martini, G; Reiber, J H; Colombo, A

    1997-04-01

    The new generation quantitative angiographic systems apply the interpolated technique to calculate the reference diameter at the site of the stenosis by integrating measurements of the segments proximal and distal to the stenosis. After stent implantation these measurements can be misleading as the treated segment, which is frequently larger than the adjacent not stented segments, is included in the measurements. The consequence is an overestimation of the reference diameter and the residual diameter stenosis. The present study was performed to compare this conventional technique of measurement with a new method which excludes the stented segment for the calculation of the reference diameter. Fifty-two lesions treated with poorly radiopaque stents (56% Palmaz-Schatz, 28% NIR, 10% Gianturco-Roubin, 6% Wallstent) expanded at high pressure (> = or 16 atm) were analyzed according to the conventional and stent excluded method. After stent implantation the reference diameter was 3.39 +/- 0.48 mm with conventional measurements and 3.02 +/- 0.45 mm with the stent excluded method (P < 0.05). The corresponding % diameter stenosis was 13 +/- 9 for the conventional technique and 1 +/- 13 for the stent excluded analysis (P < 0.05). The new approach to quantitative coronary analysis after stenting provides higher accuracy in reference diameter calculations and allows a more appropriate matching of stented segments with adjacent normal segments.

  3. 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.

  4. Thermal processing and characterization of 316LVM cardiovascular stent.

    PubMed

    Verma, Arpana; Choubey, Animesh; Raval, Ankur; Kothwala, Devesh

    2006-01-01

    In the current investigation, annealing was employed as a means to improve the mechanical performance of 316LVM coronary stents. Two different temperatures (1000 degrees C and 1150 degrees C) were explored for the thermal processing of the device. Acid pickling was done as a pre-annealing step to remove the debris and slag material attached to the stent after laser cutting. Post annealing operation involved the electrochemical polishing of the device which was also a parameter for assessment of the feasibility of the annealing process. Microstructural characterization, balloon expandability and tensile testing of the stents were performed to characterize the properties after thermal treatment. A fine grained austenitic structure with marked improvement in the % elongation (>40%) could be achieved after annealing the stents at 1000 degrees C. Balloon expandability tests of the stents annealed at 1000 degrees C indicated that the device was implantable. PMID:17119277

  5. Expanding Boundaries: N2 Cleavage and Functionalization beyond Early Transition Metals.

    PubMed

    Bezdek, Máté J; Chirik, Paul J

    2016-07-01

    Early transition metals are well known to catalyze the cleavage and functionalization of N2 . In this Highlight, recent work showing that a rhenium catalyst is also capable of carrying out this difficult task is summarized, and a synthetic cycle for the stoichiometric incorporation of atmospheric N2 into acetonitrile is presented. PMID:27248360

  6. Advances in stent technologies and their effect on clinical efficacy and safety

    PubMed Central

    Nikam, Navin; Steinberg, Toby B; Steinberg, Daniel H

    2014-01-01

    The introduction of intracoronary stents represented a major advance in interventional cardiology. While bare metal stents set the benchmark for improved safety over angioplasty, intimal hyperplasia and subsequent restenosis were important limitations. First-generation drug-eluting stents demonstrated significant improvements in efficacy, but not necessarily safety, and further technologic developments have focused on optimizing both. Current advances and understanding in stent design continue to improve on these concepts. This review summarizes past and present technology with particular emphasis on the principles underlying the efficacy and safety of drug-eluting stents, and offers a glimpse into the next generations of stents aimed at treating symptomatic coronary artery disease. PMID:24940085

  7. Coronary artery stents: advances in technology.

    PubMed

    Sheth, Sameer D; Giugliano, Robert P

    2014-10-01

    The introduction of percutaneous coronary intervention (PCI) in the late 1970s revolutionized the management of stable and unstable coronary artery disease, providing an effective, quick, safe, and increasingly widely available method for coronary revascularization for many patients. Rapid development in this field led to the introduction of a number of new technologies, including intracoronary stents that have resulted in improved efficacy and long-term safety. In this manuscript we review the experience with the 2 major available classes of stents (bare metal [BMS], drug-eluting [DES]) and describe the delivery systems for these stents. An evidence review of the large trial data comparing balloon angioplasty, BMS, and DES demonstrates the incremental advances over time, with the latest generation of DES achieving the lowest rates of restenosis, stent thrombosis, and recurrent myocardial infarction. In addition, we provide an overview of the latest developments in stent technology, including the introduction of bioresorbable stents and new stent delivery systems. These latest advances are hoped to further improve outcomes while reducing costs due to a reduction in the need for future procedures and hospitalizations due to recurrent coronary disease.

  8. Treating bilio-duodenal obstruction: combining new endoscopic technique with 6 Fr stent introducer.

    PubMed

    Maetani, Iruru; Nambu, Tomoko; Omuta, Shigefumi; Ukita, Takeo; Shigoka, Hiroaki

    2010-06-14

    Periampullary cancer may cause not only biliary but also duodenal obstructions. In patients with concomitant duodenal obstructions, endoscopic biliary stenting remains technically difficult and may often require percutaneous transhepatic biliary drainage. We describe a method of metal stent placement via a thin forward-viewing endoscope in patients with simultaneous biliary and duodenal obstruction. In two consecutive patients with biliary and duodenal obstruction due to pancreatic cancer, a new biliary metal stent mounted in a slim delivery catheter was placed via a thin forward viewing endoscope after passage across the duodenal stenosis without balloon dilation. In both patients, with our new placement technique, metallic stents were successfully placed in a short time without adverse events. After biliary stenting, one patient received curative resection and the other received duodenal stenting for palliation. Metallic stent placement with a forward-viewing thin endoscope is a beneficial technique, which can avoid percutaneous drainage in patients with bilio-duodenal obstructions due to periampullary cancer.

  9. Quantification of biomechanical interaction of transcatheter aortic valve stent deployed in porcine and ovine hearts.

    PubMed

    Mummert, Joseph; Sirois, Eric; Sun, Wei

    2013-03-01

    Success of the deployment and function in transcatheter aortic valve replacement is heavily reliant on the tissue-stent interaction. The present study quantified important tissue-stent contact variables of self-expanding transcatheter aortic valve stents when deployed into ovine and porcine aortic roots, such as the stent radial expansion force, stent pullout force, the annulus deformation response and the coefficient of friction on the tissue-stent contact interface. Braided Nitinol stents were developed, tested to determine stent crimped diameter vs. stent radial force from a stent crimp experiment, and deployed in vitro to quantify stent pullout, aortic annulus deformation, and the coefficient of friction between the stent and the aortic tissue from an aortic root-stent interaction experiment. The results indicated that when crimped at body temperature from 26 mm to 19, 21 and 23 mm stent radial forces were approximately 30-40% higher than those crimped at room temperature. Coefficients of friction leveled to approximately 0.10 ± 0.01 as stent wire diameter increased and annulus size decreased from 23 to 19 mm. Regardless of aortic annulus size and species tested, it appeared that a minimum of about 2.5 mm in annular dilatation, caused by about 60 N of radial force from stent expansion, was needed to anchor the stent against a pullout into the left ventricle. The study of the contact biomechanics in animal aortic tissues may help us better understand characteristics of tissue-stent interactions and quantify the baseline responses of non-calcified aortic tissues.

  10. Trends in Bare-Metal Stent Use in the United States in Patients Aged ≥65 Years (from the CathPCI Registry).

    PubMed

    Rymer, Jennifer A; Harrison, Robert W; Dai, David; Roe, Matthew T; Messenger, John C; Anderson, H Vernon; Peterson, Eric D; Wang, Tracy Y

    2016-10-01

    In 2006, the United States (US) Food and Drug Administration published advisory highlighting concerns for late drug-eluting stent thrombosis; its impact on US bare-metal stent (BMS) utilization is unknown. We examined rates of BMS use among Medicare patients at 946 US hospitals in the CathPCI Registry who underwent percutaneous coronary intervention (PCI) during 3 periods: (1) 2004 to 2006 preadvisory (n = 166,458); (2) 2007 to 2008 postadvisory (n = 216,318); and (3) 2012 to 2014 contemporary (n = 827,948). We examined predicted risks of target vessel revascularization and bleeding among BMS recipients by period. We compared 1-year repeat revascularization and death/myocardial infarction risks among BMS recipients immediately preadvisory and postadvisory. BMS were used in 15.8% of preadvisory, 40.9% of postadvisory, and 20.0% of contemporary PCI procedures. Although 19.5% of preadvisory BMS patients had a predicted target vessel revascularization risk ≥15%/year, this decreased to 16.7% postadvisory (p <0.001), and increased back to 18.7% among contemporary BMS recipients (p <0.001). In contrast, 12.3% of preadvisory BMS recipients had a predicted bleeding risk ≥5%/year, compared with 14.6% postadvisory (p <0.001), and 18.2% in contemporary BMS recipients (p <0.001). Postadvisory BMS recipients had a lower risk of repeat revascularization (12.8% vs 14.6%, adjusted hazard ratio 0.87, 95% CI 0.84 to 0.90) but no difference in the composite risk of death/myocardial infarction (15.9% vs 15.9%, adjusted hazard ratio 0.97, 95% CI 0.93 to 1.00). In conclusion, a surge in BMS use after the advisory was not associated with an increased risk of repeat revascularization or adverse outcomes in BMS-treated patients. One in 5 contemporary PCI procedures still involve BMS implantation. PMID:27614853

  11. Computational micromechanics of bioabsorbable magnesium stents.

    PubMed

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

    2014-06-01

    Magnesium alloys are a promising candidate material for an emerging generation of absorbable metal stents. Due to its hexagonal-close-packed lattice structure and tendency to undergo twinning, the deformation behaviour of magnesium is quite different to that of conventional stent materials, such as stainless steel 316L and cobalt chromium L605. In particular, magnesium exhibits asymmetric plastic behaviour (i.e. different yield behaviours in tension and compression) and has lower ductility than these conventional alloys. In the on-going development of absorbable metal stents it is important to assess how the unique behaviour of magnesium affects device performance. The mechanical behaviour of magnesium stent struts is investigated in this study using computational micromechanics, based on finite element analysis and crystal plasticity theory. The plastic deformation in tension and bending of textured and non-textured magnesium stent struts with different numbers of grains through the strut dimension is investigated. It is predicted that, unlike 316L and L605, the failure risk and load bearing capacity of magnesium stent struts during expansion is not strongly affected by the number of grains across the strut dimensions; however texturing, which may be introduced and controlled in the manufacturing process, is predicted to have a significant influence on these measures of strut performance.

  12. 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

  13. iStent trabecular micro-bypass stent for open-angle glaucoma.

    PubMed

    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.

  14. [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. PMID:26027299

  15. [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.

  16. 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.

  17. [Endovascular stent implantation as a treatment for iliac artery disease].

    PubMed

    Tetteroo, E; van Engelen, A D; van der Graaf, Y; Mali, W P

    2000-01-22

    A stent is an endovascular prosthesis that may be used in the treatment of intermittent claudication caused by lesions of the A. iliaca communis and the A. iliaca externa in which earlier balloon dilatation has proved insufficiently effective. The expansion is caused by inflation of an angioplasty balloon (plastic remodelling: Palmaz stent) or by self-expansion due to elastic transformation as in the Wail stent or to thermic memory metal, as in the Memotherm stent. Evaluation of the literature shows that stent placement is a safe method of treatment. The proportion of initial technical success appears to be higher than that of balloon angioplasty, especially in the treatment of total occlusions. The haemodynamic situation immediately after treatment also appears to be better in case of stent placement. Long-term comparison of the clinical efficacy is not well possible because the published studies differ with regard to patient population, definition of indication and criteria of success. PMID:10668541

  18. 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.

  19. Aortic stenting.

    PubMed

    Droc, Ionel; Calinescu, Francisca Blanca; Droc, Gabriela; Blaj, Catalin; Dammrau, Rolf

    2015-01-01

    The approach to aortic pathology is nowadays more and more endovascular at both thoracic and abdominal levels. Thoracic stenting has gained worldwide acceptance as first intention to treat pathologies of the descending thoracic aorta. Indications have been extended to aortic arch aneurysms and also to diseases of the ascending aorta. The current devices in use for thoracic endovascular repair (TEVAR) are Medtronic Valiant, Gore TAG, Cook Tx2 and Jotec. The choice of the endograft depends on the thoracic aortic pathology and the anatomical suitability. The technological evolution of the abdominal aortic endografts was very rapid, arriving now at the fourth generation. We report the results of 55 elective cases of endovascular abdominal aortic repair (EVAR) performed in two vascular surgical centers in Romania and Germany. The prostheses used were 16 E-vita Abdominal XT, 12 Excluder, eight Talent, seven PowerLink, three Endurant and nine custom-made, fenestrated or branched from Jotec. The mean follow-up was 18 months with CT-scan, duplex ultrasound and contrast-enhanced ultrasound. The mortality was 2%. EVAR tends to become the gold standard for abdominal aortic aneurysm repair. Technological development of the devices with lowest profile introduction systems will permit to extend the anatomical indications to new frontiers. PMID:26200430

  20. 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.

  1. Exclusion of Atherosclerotic Plaque from the Circulation Using Stent-Grafts: Alternative to Carotid Stenting with a Protection Device?

    SciTech Connect

    Peynircioglu, Bora Geyik, Serdar; Yavuz, Kivilcim; Cil, Barbaros E.; Saatci, Isil; Cekirge, Saruhan

    2007-09-15

    Purpose. To retrospectively assess the feasibility, safety, and clinical mid-term outcome of patients undergoing carotid artery stenting with stent-grafts. Methods. Over a 4 year period stent-grafts were used in the endovascular treatment of symptomatic internal carotid artery stenosis in 12 patients (2 women, 10 men, aged 47-83 (mean 64) years). Protection devices were not used. Possible microembolic complications were evaluated by magnetic resonance imaging (MRI) examinations of the brain before and the day after the procedure in all patients. Mean follow-up was 22 months (range 1-42 months), by Doppler ultrasonography and conventional angiography as well as clinical examination .Results. The technical success rate was 100%. A total of 13 coronary stent-grafts were used. The mean stenosis rate (in terms of diameter) was 85% and the mean length of stent-grafts used was 20.9 mm. The mean diameter to which the stent-grafts were dilated was 4.66 mm. In-hospital complications occurred in 1 patient who suffered a minor femoral access hematoma that did not require transfusion or surgical decompression. Post-stenting diffusion-weighted MRI revealed several ipsilateral silent microemboli in only 1 case, which was completely asymptomatic. Two patients had a major stroke after 2 years of follow-up. Restenosis was found in 2 patients who underwent successful balloon dilatation followed by placement of a self-expandable bare stent within the stent-grafts. Conclusions. Stent-grafts may prevent microembolic complications during stenting of atherosclerotic carotid lesions in selected cases, offering immediate exclusion of the atherosclerotic lesion from the circulation by pressing the plaque against the vessel wall. Comparative, randomized studies in larger series of patients are needed with carotid-dedicated stent-graft designs.

  2. Expanded organic building units for the construction of highly porous metal-organic frameworks.

    PubMed

    Kong, Guo-Qiang; Han, Zhi-Da; He, Yabing; Ou, Sha; Zhou, Wei; Yildirim, Taner; Krishna, Rajamani; Zou, Chao; Chen, Banglin; Wu, Chuan-De

    2013-10-25

    Two new organic building units that contain dicarboxylate sites for their self-assembly with paddlewheel [Cu2(CO2)4] units have been successfully developed to construct two isoreticular porous metal-organic frameworks (MOFs), ZJU-35 and ZJU-36, which have the same tbo topologies (Reticular Chemistry Structure Resource (RCSR) symbol) as HKUST-1. Because the organic linkers in ZJU-35 and ZJU-36 are systematically enlarged, the pores in these two new porous MOFs vary from 10.8 Å in HKUST-1 to 14.4 Å in ZJU-35 and 16.5 Å in ZJU-36, thus leading to their higher porosities with Brunauer-Emmett-Teller (BET) surface areas of 2899 and 4014 m(2) g(-1) for ZJU-35 and ZJU-36, respectively. High-pressure gas-sorption isotherms indicate that both ZJU-35 and ZJU-36 can take up large amounts of CH4 and CO2, and are among the few porous MOFs with the highest volumetric storage of CH4 under 60 bar and CO2 under 30 bar at room temperature. Their potential for high-pressure swing adsorption (PSA) hydrogen purification was also preliminarily examined and compared with several reported MOFs, thus indicating the potential of ZJU-35 and ZJU-36 for this important application. Studies show that most of the highly porous MOFs that can volumetrically take up the greatest amount of CH4 under 60 bar and CO2 under 30 bar at room temperature are those self-assembled from organic tetra- and hexacarboxylates that contain m-benzenedicarboxylate units with the [Cu2(CO2)4] units, because this series of MOFs can have balanced porosities, suitable pores, and framework densities to optimize their volumetric gas storage. The realization of the two new organic building units for their construction of highly porous MOFs through their self-assembly with [Cu2(CO2)4] units has provided great promise for the exploration of a large number of new tetra- and hexacarboxylate organic linkers based on these new organic building units in which different aromatic backbones can be readily incorporated

  3. 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

  4. A new stent with streamlined cross-section can suppress monocyte cell adhesion in the flow disturbance zones of the endovascular stent.

    PubMed

    Chen, Zengsheng; Zhan, Fan; Ding, Jun; Zhang, Xiwen; Deng, Xiaoyan

    2016-01-01

    We proposed a new stent with streamlined cross-sectional wires, which is different from the clinical coronary stents with square or round cross-sections. We believe the new stent might have better hemodynamic performance than the clinical metal stents. To test the hypothesis, we designed an experimental study to compare the performance of the new stent with the clinical stents in terms of monocyte (U-937 cells) adhesion. The results showed that when compared with the clinical stents, the adhesion of U-937 cells were much less in the new stent. The results also showed that, when Reynolds number increased from 180 (the rest condition for the coronary arteries) to 360 (the strenuous exercise condition for the coronary arteries), the flow disturbance zones in the clinical stents became larger, while they became smaller with the new stent. The present experimental study therefore suggests that the optimization of the cross-sectional shape of stent wires ought to be taken into consideration in the design of endovascular stents.

  5. Corrosion Resistance of Ti-O Film Modified 316L Stainless Steel Coronary Stents In Vitro

    NASA Astrophysics Data System (ADS)

    Liu, Hengquan; Leng, Yongxiang; Huang, Nan

    2012-03-01

    This article dealt with improving corrosion resistance of stent modified using Ti-O film. Ti-O films of various thicknesses were grown on the surface of 316L stainless steel (SS) stents by metal vacuum arc source deposition technology, and the phase composition, the thickness and the adhesion between films and substance were investigated by micro-x-ray diffraction (Micro-XRD), surface profilometer, and scanning electron microscopy (SEM) separately. The corrosion resistance of modified stent was assessed by polarization test in phosphate buffered solution (37 ± 1 °C). The result shows that the Ti-O films were very smooth and uniform. There were not any cracks and delaminations after dilation by angioplasty, the adhesion between Ti-O film and stent is satisfactory. The open circuit potential (OCP) of the Ti-O film modified stents was higher than that of the bare stents; it shows that the electrochemical stability of modified stents was more than bare stents. The polarization test result indicates that the passivation stability and anti-breakdown performance of Ti-O film stents had better than bare stents, and no pitting was observed on the surface of both modified stents, but the local film striations were found on the stent surface of the thicker film, which indicated that the Ti-O film stents with certain thickness has good corrosion resistance.

  6. Palliative stenting of the digestive tract: a case series of a single centre

    PubMed Central

    Dekkers, Pascale E.P.

    2013-01-01

    Background and aim Obstruction of the gastrointestinal tract due to cancer can be treated with stenting. The aim was to review the local experience with endoscopic stenting. All patients treated with stenting in a ten years period from 2001-2010 were studied. Results Fifty one patients received 57 stents because of oesophageal cancer. Mean survival after stent placement was 141 days. No case of perforation occurred. In nine cases (17%) clogging with food occurred. Tumour overgrowth was noted in four cases. Twenty four patients received 28 stents in their colon or rectum. The stents were placed in the rectum (n=6), the sigmoid (n=14), the descending colon (n=1), and the transverse colon (n=3). Mean survival was 276 days. Perforation did not occur. Tumour ingrowth was seen in two patients. One patient received a second stent. Dislocation occurred in two cases. There were two cases of clogging (8%) by stool. Fourteen patients received a total of 18 stents because of obstructing stomach cancer. Mean survival after placement was 121 days. There was no perforation, one case of clogging, and four cases of tumour ingrowth. Eight patients had stent placement in their duodenum. Mean survival after stent placement was 84 days. No perforation or clogging occurred. But three cases of tumour ingrowth were seen. Conclusions The present series shows that placement of expandable stents in the digestive tract in normal daily practice is feasible, safe, with a low number of complications, and provides good palliation for their remaining life. PMID:23450097

  7. Mechanical properties and in vitro degradation of bioresorbable knitted stents.

    PubMed

    Nuutinen, Juha-Pekka; Välimaa, Tero; Clerc, Claude; Törmälä, Pertti

    2002-01-01

    The aim of this study was to characterize the mechanical properties and in vitro degradation of bioresorbable knitted stents. Each stent was knitted using a single self-reinforced fibre made out of either PLLA or 96L/4D PLA or 80L/20G PLGA. The mechanical and physical properties of the fibres and stents were measured before and after gamma sterilization, as well as during in vitro degradation. The mechanical properties of the knitted stents made out of bioresorbable fibres were similar to those of commercially available metallic stents. The knitting geometry (loop height) had a marked effect on the mechanical properties of the stents. The rate of in vitro degradation in mechanical and physical properties for the PLLA and 96L/4D PLA stents was similar and significantly lower than that of the 80L/20G PLGA stents. The 80L/20G PLGA stents lost about 35% of their initial weight at 11 weeks. At this time, they had lost all their compression resistance strength. These data can be used as a guideline in planning further studies in vivo. PMID:12555898

  8. 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.

  9. Unintentional Long-Term Esophageal Stenting due to a Complete Response in a Patient with Stage UICC IV Adenocarcinoma of the Gastroesophageal Junction.

    PubMed

    Paeschke, Anna; Bojarski, Christian; Küpferling, Susanne; Hucklenbroich, Thomas; Siegmund, Britta; Daum, Severin

    2016-01-01

    Endoscopic stent implantation is a common short-treatment option in palliative settings in patients with esophageal cancer. Advanced disease is associated with low survival rates; therefore, data on the long-term outcome are limited. So far, cases of long-term remission or even cure of metastasized adenocarcinoma of the gastroesophageal junction or stomach (AGS) have only been reported from Asia. A 51-year-old male patient primarily diagnosed with metastasized adenocarcinoma of the gastroesophageal junction (GEJ) [type I, cT3cN+cM1 (hep), CEA positive, UICC stage IV] received palliative esophageal stenting with a self-expandable metal stent. As disease progressed after four cycles with epirubicin, oxaliplatin, and capecitabin, treatment was changed to 5-FU and Irinotecan. The patient did not return after 5 cycles of FOLFIRI, but presented 4 years later with mild dysphagia. Endoscopy surprisingly revealed no relevant stenosis or stent migration. Repeated histological analyses of a residual mass at the GEJ did not detect malignancy. Since the initially diagnosed hepatic metastases were no longer detectable by computed tomography, cure from esophageal cancer was assumed. Dysphagia was ascribed to esophageal motility disorder by a narrowed esophageal lumen after long-term stenting. Thus, endoscopic stent implantation is an important method in palliative treatment of dysphagia related to AGS. New systemic treatment strategies like trastuzumab in Her2neu positive cases or new VEGF-inhibitors like ramucirumab will lead to more long-time survivors with AGS. In conclusion, future endoscopic treatment strategies in AGS represent a challenge for the development of new stent techniques in either extraction or programmed complete dissolution. PMID:27462189

  10. Unintentional Long-Term Esophageal Stenting due to a Complete Response in a Patient with Stage UICC IV Adenocarcinoma of the Gastroesophageal Junction

    PubMed Central

    Paeschke, Anna; Bojarski, Christian; Küpferling, Susanne; Hucklenbroich, Thomas; Siegmund, Britta; Daum, Severin

    2016-01-01

    Endoscopic stent implantation is a common short-treatment option in palliative settings in patients with esophageal cancer. Advanced disease is associated with low survival rates; therefore, data on the long-term outcome are limited. So far, cases of long-term remission or even cure of metastasized adenocarcinoma of the gastroesophageal junction or stomach (AGS) have only been reported from Asia. A 51-year-old male patient primarily diagnosed with metastasized adenocarcinoma of the gastroesophageal junction (GEJ) [type I, cT3cN+cM1 (hep), CEA positive, UICC stage IV] received palliative esophageal stenting with a self-expandable metal stent. As disease progressed after four cycles with epirubicin, oxaliplatin, and capecitabin, treatment was changed to 5-FU and Irinotecan. The patient did not return after 5 cycles of FOLFIRI, but presented 4 years later with mild dysphagia. Endoscopy surprisingly revealed no relevant stenosis or stent migration. Repeated histological analyses of a residual mass at the GEJ did not detect malignancy. Since the initially diagnosed hepatic metastases were no longer detectable by computed tomography, cure from esophageal cancer was assumed. Dysphagia was ascribed to esophageal motility disorder by a narrowed esophageal lumen after long-term stenting. Thus, endoscopic stent implantation is an important method in palliative treatment of dysphagia related to AGS. New systemic treatment strategies like trastuzumab in Her2neu positive cases or new VEGF-inhibitors like ramucirumab will lead to more long-time survivors with AGS. In conclusion, future endoscopic treatment strategies in AGS represent a challenge for the development of new stent techniques in either extraction or programmed complete dissolution. PMID:27462189

  11. Coronary Stent Thrombosis: Current Insights into New Drug-Eluting Stent Designs

    PubMed Central

    Kim, Hyun Kuk

    2012-01-01

    The advances of interventional cardiology have been achieved by new device development, finding appropriate drug regimes, and understanding of pathomechanism. Drug-eluting stents (DES) implantation with dual anti-platelet therapy reduced revascularization without increasing mortality or myocardial infarction compared with bare-metal stenting. However, late-term stent thrombosis (ST) and restenosis limited its value and raised the safety concern. Main mechanisms of this phenomenon are impaired endothelialization and hypersensitivity reaction with polymer. The second generation DES further improved safety and/or efficacy by using thinner stent strut and biocompatible polymer. Recently, new concept DES with biodegradable polymer, polymer-free and bioabsorbable scaffold are under investigation in the quest to minimize the risk of ST. PMID:23323218

  12. High fidelity virtual stenting (HiFiVS) for intracranial aneurysm flow diversion: in vitro and in silico.

    PubMed

    Ma, Ding; Dumont, Travis M; Kosukegawa, Hiroyuki; Ohta, Makoto; Yang, Xinjian; Siddiqui, Adnan H; Meng, Hui

    2013-10-01

    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.

  13. Aortic rupture due to pneumococcal infection in aortoiliac stents.

    PubMed

    Mlynski, Amélie; Mordant, Pierre; Dufour, Guillaume; Augustin, Pascal; Lesèche, Guy; Castier, Yves

    2011-06-01

    We report a rare case of pneumococcal aortitis secondary to endovascular bare-metal stent infection. The patient was a 70-year-old man presenting with back pain 1 year after aortoiliac implantation of bare-metal kissing stents. Final diagnosis was microbial aortitis due to Streptococcus pneumoniae involving the stents that resulted in a contained aortic rupture requiring urgent surgical treatment. Emergency extra-anatomic revascularization, excision of the infected tissues, and appropriate antibiotic therapy led to a favorable outcome. A high index of suspicion is required in such a situation because the mortality rate is very high in the absence of appropriate treatment. PMID:21498029

  14. 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

  15. Nitinol Stent Fatigue in a Peripheral Human Artery Subjected to Pulsatile and Articulation Loading

    NASA Astrophysics Data System (ADS)

    Harvey, Sean Michael

    2011-07-01

    Nitinol self-expanding stents are used to treat peripheral occluded vessels such as the superficial femoral artery or the carotid. The complex vessel articulation requires a stent device that is flexible and kink resistant yet durable. The present study shows how the latest advances in commercially available engineering software tools permit engineering simulations of the many aspects of the Nitinol stent design and analysis. Two stent geometries are evaluated: a helical type stent design, and a more traditional straight strut, with multiple crowns design. The fatigue performance of the two stents is compared. The results show that advanced nonlinear finite element simulations and fatigue predictions of the Nitinol stent are possible today inside realistic simulated human arteries. The finite element analysis software used in this study is SimXpert, Marc, and Mentat (MSC Software, Santa Ana, CA).

  16. 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.

  17. Virtual stenting workflow with vessel-specific initialization and adaptive expansion for neurovascular stents and flow diverters.

    PubMed

    Paliwal, Nikhil; Yu, Hongyu; Xu, Jinhui; Xiang, Jianping; Siddiqui, Adnan H; Yang, Xinjian; Li, Haiyun; Meng, Hui

    2016-10-01

    Endovascular intervention using traditional neurovascular stents and densely braided flow diverters (FDs) have become the preferred treatment strategies for traditionally challenging intracranial aneurysms. 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.

  18. 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

  19. Histological analysis of cobalt-chromium stents with and without Camouflage® polymer coating: experimental porcine carotid artery model.

    PubMed

    Grudtner, Marco Aurélio; de Lara Elesbão, Joao Luiz; Gutierrez, Paulo Sérgio; Meyer, Fabíola Schons; Pereira, Adamastor Humberto

    2011-04-01

    This study evaluated the arterial response to cobalt-chromium stents with and without polymer coating (Camouflage®, Hemoteq AG, Wuerselen, Germany) implanted in pigs. Cobalt-chromium balloon-expandable stents (4 × 16 mm) were implanted in the common carotid arteries of nine pigs. Histological analysis of endothelialization, inflammation and injury was performed one month later. All stents were successfully deployed, and all but one animal survived the 30 study days. All arteries were patent. Endothelialization was nearly complete in most sections of all carotid stents in both groups. There were mild inflammatory infiltrate and mild-to-moderate injury, which were associated with the stent shafts and not significantly different between groups. Our findings suggest that, in porcine carotid arteries, the histological response to balloon-expandable cobalt-chromium stents coated with polymer (Camouflage®, Hemoteq AG) is similar to the response to non-coated cobalt-chromium stents.

  20. Stent thrombosis: incidence and related factors in the R.I.S.E. Registry(Registro Impianto Stent Endocoronarico)

    PubMed

    De Servi, S; Repetto, S; Klugmann, S; Bossi, I; Colombo, A; Piva, R; Giommi, L; Bartorelli, A; Fontanelli, A; Mariani, G; Klersy, C

    1999-01-01

    Although stent thrombosis has been greatly reduced by adequate stent expansion with high-pressure balloon inflations and by the use of antiplatelet drugs, this event is still frightening, as it may lead to acute myocardial ischemia resulting in acute myocardial infarction or sudden death. Therefore, the definition of factors associated with stent thrombosis may provide a better understanding of the mechanisms underlying this phenomenon and may permit us to define therapeutic strategies to further reduce its occurrence. The purpose of this study was to assess factors responsible for the occurrence of stent thrombosis after coronary stent implantation in 939 consecutive patients enrolled in the Registro Impianto Stent Endocoronarico (R.I.S.E. Study Group). Consecutive patients undergoing coronary stent implantation at 16 medical centers in Italy were prospectively enrolled in the registry. Clinical data, and qualitative and quantitative angiographic findings were obtained from data collected in case report forms at each investigator site. The study group consisted of 781 men and 158 women with a mean age of 59 yr: 1,392 stents were implanted in 1,006 lesions and expanded at a maximal inflation pressure of 14.7 +/- 3 atm. The great majority of patients (92%) received only antiplatelet drugs after coronary stenting. During hospitalization there were 45 major ischemic complications in 39 patients (4.2%): 13 events were related to acute or subacute thrombosis (1.4%). Another stent thrombotic event occurred in the first month of follow-up. On multivariate logistic regression analysis, stent thrombosis was related to the following factors: unplanned stenting (OR 3.46, 95% CI 1.65-7.23), unstable angina (OR 3.37, 95% CI 1.11-10.14) and maximal inflation pressure (OR 0.83, 95% CI 0.75-0.93). In conclusion, this registry shows that in an unselected population of patients undergoing coronary stenting, stent thrombosis occurs in less than 2% of patients and is significantly

  1. 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.

  2. A numerical framework for the mechanical analysis of dual-layer stents in intracranial aneurysm treatment.

    PubMed

    Alherz, Ali I; Tanweer, Omar; Flamini, Vittoria

    2016-08-16

    Dual-layer stents and multi-layer stents represent a new paradigm in endovascular interventions. Multi-layer stents match different stent designs in order to offer auxiliary functions. For example, dual-layer stents used in the endovascular treatment of intracranial aneurysms, like the FRED(TM) (MicroVention, CA) stent, combine a densely braided inner metallic mesh with a loosely braided outer mesh. The inner layer is designed to divert blood flow, whereas the outer one ensures microvessels branching out of the main artery remain patent. In this work, the implemented finite element (FE) analysis identifies the key aspects of dual-stent mechanics. In particular, dual-layer stents used in the treatment of intracranial aneurysms require the ability to conform to very narrow passages in their closed configuration, while at the same time they have to provide support and stability once deployed. This study developed a numerical framework for the analysis of dual-layer stents for endovascular intracranial aneurysm treatment. Our results were validated against analytical methods. For the designs considered, we observed that foreshortening was in average 37.5%±2.5%, and that doubling the number of wires in the outer stent increased bending moment by 23%, while halving the number of wires of the inner stent reduced von Mises stress by 2.3%. This framework can be extended to the design optimization of multi-layer stents used in other endovascular treatments.

  3. 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.

  4. Comparison of Devices Used for Stent-Assisted Coiling of Intracranial Aneurysms

    PubMed Central

    Izar, Benjamin; Rai, Ansaar; Raghuram, Karthikram; Rotruck, Jill; Carpenter, Jeffrey

    2011-01-01

    Introduction Two self-expandable stents, the Neuroform and the Enterprise stent, are widely used for stent-assisted coiling (SAC) of complex shaped intracranial aneurysms. However, comparative knowledge about technical feasibility, peri- and post-procedural morbidity and mortality, packing densities as well as follow-up data is limited. Material and Methods We conducted a retrospective study to investigate differences in aneurysms stented with the Enterprise or Neuroform stents. Angiographic follow-up (mean 19.42 months) was available in 72.6% (61/84) of aneurysms treated with stent-assisted coiling. We further sought to compare stent-assisted coiling to a matched patient population with aneurysms treated by conventional coil embolization. Results The stenting success rate of the Enterprise was higher compared to the Neuroform stent (46/48 and 42/51, respectively). In 5 of 9 cases in which the Neuroform stent was not navigable to the landing zone, we successfully deployed an Enterprise stent instead. Eventually, 42 aneurysms were coiled after stenting in each group. We observed no significant differences in peri-procedural complication rate, post-procedural hospital stay, packing density, recurrence rate or number of in-stent stenosis. Strikingly, 36.1% of followed aneurysms in the SAC group showed progressive occlusion on angiographic follow-up imaging. The packing density was significantly higher in aneurysms treated by SAC as compared to conventionally coiled aneurysms, while recanalization rate was significantly lower in the SAC group. Conclusion The procedural success rate is higher using the Enterprise, but otherwise both stents exhibited similar characteristics. Lower recurrence frequency and complication rates comparable to conventional coil embolization emphasize the importance of stent-assisted coiling in the treatment of complex aneurysms. Progressive occlusion on angiographic follow-up was a distinct and frequent observation in the SAC group and may in

  5. Novel nanocomposite stent coating releasing resveratrol and quercetin reduces neointimal hyperplasia and promotes re-endothelialization.

    PubMed

    Kleinedler, James J; Foley, John D; Orchard, Elysse A; Dugas, Tammy R

    2012-04-10

    Late-term thrombosis associated with drug-eluting stents may be due to the non-selective actions of antimitogenic drugs on endothelial cells, leading to delayed vascular healing after stenting angioplasty. Currently, there is a need for stent-based therapies that can both attenuate neointimal hyperplasia and promote re-endothelialization. The aim of this study was to compare the effects of a resveratrol (R)- and quercetin (Q)-eluting stent with that of a bare metal stent (BMS) on neointimal hyperplasia and re-endothelialization in a rat model of arterial angioplasty and stenting. Miniature stents (2.5×1.25mm) were sprayed with nanocomposite coatings containing two concentrations of R:Q (50:25μg/cm(2) (RQ1) or 150:75μg/cm(2) (RQ2)). The stents were deployed into the common carotid artery of rats and their impact on vascular remodeling was compared to that of BMS. Luminal stenosis in arteries stented with RQ2-eluting stents was reduced by 64.6% (p<0.05) compared to arteries stented with BMS. Accompanying this effect was a 59.8% reduction in macrophage infiltration (p<0.05). There were no differences found between RQ1 and BMS. Finally, the RQ2-coated stent accelerated re-endothelialization by 50% compared with BMS (p<0.05). Thus, compared with BMS, local delivery of R and Q from a stent platform significantly reduced in-stent stenosis, while promoting re-endothelialization. These data suggest that R and Q may be favorable candidates for novel stent coatings, potentially reducing the risk of late thrombosis associated with drug-eluting stents.

  6. Conservative reconstruction using stents as salvage therapy for disruption of esophago-gastric anastomosis.

    PubMed

    Oshikiri, Taro; Yamamoto, Yoshinobu; Miki, Ikuya; Tsuda, Masahiro; Nakamura, Tetsu; Fujino, Yasuhiro; Tominaga, Masahiro; Kakeji, Yoshihiro

    2015-07-28

    Esophagectomy with extended lymphadenectomy and gastric conduit reconstruction is a radical procedure for the treatment of esophageal cancer that is associated with a high morbidity rate. Gastric conduit necrosis is a fatal complication that occurs in 2% of patients. Conventionally, two-stage salvage surgery consisting of removal of the necrotic gastric conduit followed by reconstruction has been performed; however, this procedure has a high morbidity rate. We describe a 61-year-old man who underwent minimally invasive esophagectomy complicated by slowly progressive gastric conduit necrosis associated with complete neck drainage and a stable overall condition. There was a 2 cm gap in the anastomosis. Because there was no evidence of residual gastric conduit necrosis, a removable, covered self-expanding metal stent (SEMS) was inserted to bridge the anastomosis. The stent was fixed to the patient's ear with silk thread through the lasso on its proximal end to prevent migration. Eight weeks after insertion, the stent was removed easily without any associated complications. The anastomotic defect was completely bridged with granulation tissue, showing progressive epithelialization without leakage or stenosis. The patient was discharged home in good general health. This is the first report of the successful conservative management of esophago-gastric conduit anastomosis disruption with SEMS placement. PMID:26229414

  7. 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

    2015-04-01

    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.

  8. In vivo Evaluation of Cenderitide-Eluting Stent (CES) II.

    PubMed

    Huang, Yingying; Ng, Xu Wen; Lim, Soon Ghim; Chen, Horng Haur; Burnett, John C; Boey, Yin Chiang Freddy; Venkatraman, Subbu S

    2016-02-01

    The use of drug-eluting coronary stents has led to significant reduction in in-stent restenosis (ISR), but led to delayed endothelialization, necessitating the prolonged use of expensive anti-thrombotic drugs with their side-effects. Cenderitide (CD-NP) is a novel anti-proliferative chimeric peptide of semi-endothelial origin. Our previous work in vitro has demonstrated; that the smooth muscle cells were inhibited significantly more than endothelial cells which is the desirable feature of an anti-restenosis drug. This work reports the effects of implantation of a centeritide-eluting stent (CES) on ISR and endothelialization in an in vivo model. CESs were produced by coating bare metallic stents with CD-NP entrapped in biodegradable poly(ε-caprolactone) using an ultrasonic spray coater. A total of 32 stents were successfully implanted into 16 pigs, and all animal survived for 28 days. The plasma levels of CD-NP were significantly higher in the CES group than in the control group (bare metal stents and polymer-coated stent) at post-stenting, indicating the successful release of CD-NP from the stent in vivo. Furthermore, SEM analysis results showed the greater endothelial coverage of the stent struts, as well as between the struts in CES group. Moreover, histological results showed mild inflammation, and low fibrin score at 28 days. However, plasma cGMP (second messenger, cyclic 3',5' guanosine monophosphate) does not show a significant difference, and the CES is also unable to show significant difference in terms on neointimal area and stenosis, in comparison to BMS at 28 days.

  9. 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

    2008-01-01

    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.

  10. [Recent developments of drug eluting stent coatings].

    PubMed

    Chen, Wen-ping; Zhan, Hong-bing

    2011-11-01

    Drug eluting stents (DESs) have revolutionized the interventional cardiology over the past decade since the first DES became commercially available in Europe in 2002. Compared to bare metal stents that are deployed to keep the vessel open by mechanical force, DESs have an additional function of reducing restenosis by the action of the drug on the target site. Coatings on the stent surface which ensure the maximum delivery of therapeutic agents to the target site with minimal systematic toxicity, also play an important role in adjusting the drug release profile. Coating material and technology not only affect the surface biocompatibility and the integrity maintenance during the implanting process, but also decide the way of drug delivering and transmitting from the coating. This paper reviews the basic principles of DES coating design, the categories of DES coatings, the commonly used clinical DES coatings and their efficiency in reducing restenosis, and finally provides the future perspectives for DES coatings. PMID:22260019

  11. 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

  12. 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.

  13. Temporary Strecker Stent for Management of Acute Dissection in Popliteal and Crural Arteries

    SciTech Connect

    Manke, Christoph; Geissler, Angela; Seitz, Johannes; Lenhart, Markus; Kasprzak, Piotr; Gmeinwieser, Josef; Feuerbach, Stefan

    1999-03-15

    Stent placement is a widely used bail-out treatment for dissection of peripheral arteries. Below the level of the superficial femoral artery permanent stenting is complicated by a high incidence of subacute thrombosis and restenosis. We present two cases of arterial occlusion due to acute iatrogenic dissection of the popliteal and distal fibular arteries. Successful treatment was achieved with a new bail-out procedure. Strecker stents were implanted to seal off the dissection flap. Stents were retrieved easily after 24 hr using a myocardial biopsy forceps. After stent retrieval the temporarily stented segments were patent and showed a larger lumen compared with segments treated by balloon dilatation alone. Temporary stenting is a simple and safe procedure and offers the advantage of tacking up dissection membranes and preventing recoil. Persistent presence of a metallic implant as a source of continued injury and stimulus for intimal proliferation is avoided.

  14. Microwave Spectrometry for the Assessment of the Structural Integrity and Restenosis Degree of Coronary Stents

    NASA Astrophysics Data System (ADS)

    Arauz-Garofalo, Gianluca; Lopez-Dominguez, Victor; Garcia-Santiago, Antoni; Tejada, Javier; O'Callaghan, Joan; Rodriguez-Leor, Oriol; Bayes-Genis, Antoni; Gmag Team; Hugtp Team; Upc Team

    2013-03-01

    Cardiovascular disease is the main cause of death worldwide. Coronary stents are one of the most important improvements to reduce deaths from cardiovascular disorders. Stents are prosthetic tube-shaped devices which are used to rehabilitate obstructed arteries. Despite their obvious advantages, reocclusion occurs in some cases arising from restenosis or structural distortions, so stented patients require chronic monitoring (involving invasive or ionizing procedures). We study microwave scattering spectra (between 2.0 - 18.0 GHz) of metallic stents in open air, showing that they behave like dipole antennas in terms of microwave scattering. They exhibit characteristic resonant frequencies in their microwave absorbance spectra that are univocally related to their length and diameter. This fact allows one to detect stent fractures or collapses. We also investigate the ``dielectric shift'' in the frequency of the resonances mentioned above due to the presence of different fluids along the stent lumen. This shift could give us information about the restenosis degree of implanted stents.

  15. Midterm Outcome of Femoral Artery Stenting and Factors Affecting Patency

    PubMed Central

    Yu, Jae Seoung; Park, Keun-Myoung; Jeon, Yong Sun; Cho, Soon Gu; Hong, Kee Chun; Shin, Woo Young; Choe, Yun-Mee; Shin, Seok-Hwan; Kim, Kyung Rae

    2015-01-01

    Purpose: The purpose of this study was to evaluate the early and midterm results of superficial femoral artery (SFA) stenting with self-expanding nitinol stents and to identify the factors affecting patency. Materials and Methods: SFA stenting was performed in 165 limbs of 117 patients from January 2009 to December 2013. Patients were followed-up for the first occurrence of occlusion or stenosis based on computed tomography and duplex scan results and a decrease in ankle brachial index of >15%. Results: During the follow-up period (mean, 15.3±3.2 months), no early thrombotic reocclusions occurred within 30 days, but in-stent restenosis developed in 78 limbs. The primary patency rates at 6, 12, 18, and 24 months were 78%, 66%, 42%, and 22%, respectively, and the secondary patency rates were 85%, 72%, 58%, and 58%, respectively. TASC II C or D lesions, stent length >8 cm, number of patent tibial arteries and diabetes were significantly associated with reintervention. Conclusion: The midterm results of stenting for SFA occlusive disease were disappointing because the primary and secondary patency rates at two years were 22% and 58%, respectively. Reintervention after SFA stenting remains a major problem, particularly in patients with diabetes mellitus or long TASC II C or D lesions. PMID:26719837

  16. 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

  17. [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.

  18. [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. PMID:27382696

  19. New avenues for ligand-mediated processes--expanding metal reactivity by the use of redox-active catechol, o-aminophenol and o-phenylenediamine ligands.

    PubMed

    Broere, Daniël L J; Plessius, Raoul; van der Vlugt, Jarl Ivar

    2015-10-01

    Redox-active ligands have evolved from being considered spectroscopic curiosities - creating ambiguity about formal oxidation states in metal complexes - to versatile and useful tools to expand on the reactivity of (transition) metals or to even go beyond what is generally perceived possible. This review focusses on metal complexes containing either catechol, o-aminophenol or o-phenylenediamine type ligands. These ligands have opened up a new area of chemistry for metals across the periodic table. The portfolio of ligand-based reactivity invoked by these redox-active entities will be discussed. This ranges from facilitating oxidative additions upon d(0) metals or cross coupling reactions with cobalt(iii) without metal oxidation state changes - by functioning as an electron reservoir - to intramolecular ligand-to-substrate single-electron transfer to create a reactive substrate-centered radical on a Pd(ii) platform. Although the current state-of-art research primarily consists of stoichiometric and exploratory reactions, several notable reports of catalysis facilitated by the redox-activity of the ligand will also be discussed. In conclusion, redox-active ligands containing catechol, o-aminophenol or o-phenylenediamine moieties show great potential to be exploited as reversible electron reservoirs, donating or accepting electrons to activate substrates and metal centers and to enable new reactivity with both early and late transition as well as main group metals. PMID:26148803

  20. New avenues for ligand-mediated processes--expanding metal reactivity by the use of redox-active catechol, o-aminophenol and o-phenylenediamine ligands.

    PubMed

    Broere, Daniël L J; Plessius, Raoul; van der Vlugt, Jarl Ivar

    2015-10-01

    Redox-active ligands have evolved from being considered spectroscopic curiosities - creating ambiguity about formal oxidation states in metal complexes - to versatile and useful tools to expand on the reactivity of (transition) metals or to even go beyond what is generally perceived possible. This review focusses on metal complexes containing either catechol, o-aminophenol or o-phenylenediamine type ligands. These ligands have opened up a new area of chemistry for metals across the periodic table. The portfolio of ligand-based reactivity invoked by these redox-active entities will be discussed. This ranges from facilitating oxidative additions upon d(0) metals or cross coupling reactions with cobalt(iii) without metal oxidation state changes - by functioning as an electron reservoir - to intramolecular ligand-to-substrate single-electron transfer to create a reactive substrate-centered radical on a Pd(ii) platform. Although the current state-of-art research primarily consists of stoichiometric and exploratory reactions, several notable reports of catalysis facilitated by the redox-activity of the ligand will also be discussed. In conclusion, redox-active ligands containing catechol, o-aminophenol or o-phenylenediamine moieties show great potential to be exploited as reversible electron reservoirs, donating or accepting electrons to activate substrates and metal centers and to enable new reactivity with both early and late transition as well as main group metals.

  1. 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.

  2. 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.

  3. In vitro and in vivo testing of a novel, hyperelastic thin film nitinol flow diversion stent.

    PubMed

    Kealey, C P; Chun, Y J; Viñuela, F E; Mohanchandra, K P; Carman, G P; Viñuela, F; Levi, D S

    2012-04-01

    A flexible, low profile, flow diversion stent could replace endovascular coiling for the treatment of intracranial aneurysms. Micropatterned-thin film nitinol (TFN) is a novel biomaterial with high potential for use in next-generation endovascular devices. Recent advancements in micropatterning have allowed for fabrication of a hyperelastic thin film nitinol (HE-TFN). In this study, the authors describe in vitro and in vivo testing of novel HE-TFN based flow diverting stents. Two types of HE-TFN with expanded pores having long axes of 300 and 500 μm were used to fabricate devices. In vitro examination of the early thrombotic response in whole blood showed a possible mechanism for the device's function, whereby HE-TFN serves as a scaffold for blood product deposition. In vivo testing in swine demonstrated rapid occlusion of model wide-neck aneurysms. Average time to occlusion for the 300-μm device was 10.4 ± 5.5 min. (N = 5) and 68 ± 30 min for the 500-μm device (N = 5). All aneurysms treated with bare metal control stents remained patent after 240 min (N = 3). SEM of acutely harvested devices supported in vitro results, demonstrating that HE-TFN serves as a scaffold for blood product deposition, potentially enhancing its flow-diverting effect. Histopathology of devices after 42 days in vivo demonstrated a healthy neointima and endothelialization of the aneurysm neck region. HE-TFN flow-diverting stents warrant further investigation as a novel treatment for intracranial aneurysms.

  4. [Coronary Artery Bypass Grafting for In-stent Restenosis Probably Caused by Allergic Response;Report of a Case].

    PubMed

    Eda, Tadahito; Teshima, Yuto; Suga, Kazumasa; Hayashi, Kazutaka; Miyake, Yuji; Umeda, Hisashi; Ishiki, Ryoji

    2016-07-01

    A 58-year-old female presented to our hospital with recurrence of chest pain. She had undergone coronary intervention using biolimus-eluting-stent for total occlusion of the left anterior descending artery(LAD) 3 years before. Since then in-stent restenosis had repeated 4 times in 3 years. In the interim, another everolimus-eluting-stent had been placed on the same lesion. The contact metal allergic patch test revealed the existence of allergic response to nickel and cobalt which were the structural components of these stents. She underwent off-pump coronary artery bypass grafting, and these stents were removed. The invasions of macrophages and eosinophils around the stent-s were pathologically proven. One year after surgery she is doing well without angina or allergic symptom. These observations suggested the allergic reaction of the coronary artery against the stents. PMID:27365069

  5. 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

  6. 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.

  7. 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.

  8. Comparison of endoscopic stenting for malignant biliary obstruction: A single-center study

    PubMed Central

    Yamamoto, Ryuichi; Takahashi, Masatomo; Osafune, Yasuyo; Chinen, Katsuya; Kato, Shingo; Nagoshi, Sumiko; Yakabi, Koji

    2015-01-01

    AIM: To evaluate the efficacy and safety of single-step endoscopic placement of self-expandable metallic stents (SEMS) for treatment of obstructive jaundice. METHODS: A retrospective study was performed among 90 patients who underwent transpapillary biliary metallic stent placement for malignant biliary obstruction (MBO) between April 2005 and October 2012. The diagnosis of primary disease and MBO was based on abdominal ultrasound, computed tomography, magnetic resonance imaging, endoscopic ultrasound, endoscopic retrograde cholangiopancreatography with brush cytology, biopsy, and/or a combination of these modalities. The type of SEMS (covered or non-covered, 8 mm or 10 mm in diameter) was determined by the endoscopist. Ninety patients were divided into two groups: group 1 (49 patients) who underwent a single-step SEMS placement and group 2 (41 patients) who underwent a two-step SEMS placement. The technical success rate, complication rate, stent patency, and patient survival rate were compared between the groups. In addition, to identify the clinical prognostic factors associated with patient survival, the following variables were evaluated in Cox-regression analysis: gender, age, etiology of MBO (pancreatic cancer or non-pancreatic cancer), clinical stage (IVb; with distant metastases or IVa >; without distant metastases), chemotherapy (with or without), patency of the stent, and the use of single-step or two-step SEMS. RESULTS: Immediate technical success was achieved in 93.9% (46/49) in group 1 and in 95.1% (39/41) in group 2, with no significant difference (P = 1.0). Similarly, there was no difference in the complication rates between the groups (group 1, 4.1% and group 2, 4.9%; P = 0.62). Stent failure was observed in 10 cases in group 1 (20.4%) and in 16 cases in group 2 (39.0%). The patency of stent and patient survival revealed no difference between the two groups with Kaplan-Meier analysis, with a mean patency of 111 ± 17 d in group 1 and 137 ± 19 d in

  9. 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

  10. 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.

  11. Late Migration of Two Covered Biliary Stents Through a Spontaneous Bilioenteric Fistula in a Patient with Malignant Biliary Obstruction

    SciTech Connect

    Krokidis, Miltiadis E.; Hatzidakis, Adam A. Manousaki, Eirini G.; Gourtsoyiannis, Nicholas C.

    2008-01-15

    We report a case of simultaneous late migration of two ePTFE-FEP covered biliary endoprostheses (Viabil, W.L. Gore, Flagstaff, AZ, USA) that were percutaneously implanted for the treatment of malignant obstructive jaundice. The first Viabil covered stent was placed successfully without any evidence of dislocation or other complication during follow-up. Occlusion of the stent occurred 4 months later and was treated with the placement of a second stent of the same type. Thirteen months later the patient became symptomatic. Percutaneous transhepatic cholangiography (PTC) revealed the presence of a choledocho-duodenal fistula and the disappearance of the two endoprostheses previously implanted. A third metallic stent was then percutaneously positioned through the bilioenteric fistula. The computed tomography scan that followed for the detection of the metallic bodies did not reveal the dislocated metallic stents. Stent migration is a well-known complication of uncovered metallic stents, though Viabil stent migration is assumed to be most unlikely to happen due to the stent's anchoring barbs. Furthermore, the stent had already been tightly fixed by tumor over- and ingrowth, as recognized in previous imaging. This is a very unusual case, describing the disappearance of two metallic foreign bodies encapsulated by tumor.

  12. Next generation covered stents made from nanocomposite materials: A complete assessment of uniformity, integrity and biomechanical properties.

    PubMed

    Farhatnia, Yasmin; Pang, Jun Hon; Darbyshire, Arnold; Dee, Ryan; Tan, Aaron; Seifalian, Alexander M

    2016-01-01

    Covered stents are stents wrapped with a thin polymeric membrane, and are typically used to treat vessel aneurysms and seal perforated arteries. Current covered stents suffer from restenosis due to limitations in material and fabrication methods which leaves metallic struts directly exposed to blood. We have developed a biocompatible and haemocompatible nanocomposite polymer, polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU). We devised a novel combination of ultrasonic spray atomisation system and dip-coating process to produce small calibre covered stents with metal struts fully embedded within the membrane, which also yields greater coating uniformity. Stent-polymer bonding was enhanced via silanisation and coating of reactive pre-polymer. Platelet studies supported the non-thrombogenicity of POSS-PCU. Biomechanical performances including diametrical compliance, bending strength, radial strength and recoil were evaluated and optimised. This proof-of-principle manufacturing technique could lead to the development of next-generation small calibre adult and paediatric covered stents. These stents are currently undergoing preclinical trial. From the Clinical Editor: The use of stents to treat vascular diseases is now the standard of care in the clinical setting. Nonetheless, a major problem of the current stents is the risk of restenosis and thrombosis. The authors developed a nanocomposite material using polyhedral oligomeric silsesquioxane and poly(carbonate-urea) urethane (POSS-PCU) and incorporated into metallic stents. Preliminary data have already shown promising results. It is envisaged that this would further lead to better stent technology in the future.

  13. 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

  14. Should transjugular intrahepatic portosystemic shunt stent grafts be underdilated?

    PubMed

    Gaba, Ron C; Parvinian, Ahmad; Minocha, Jeet; Casadaban, Leigh C; Knuttinen, M Grace; Ray, Charles E; Bui, James T

    2015-03-01

    Although underdilation of transjugular intrahepatic portosystemic shunt (TIPS) stent grafts is commonly performed to limit complications arising from excessive portosystemic shunting, it is uncertain whether underdilated stents retain their smaller diameter indefinitely or eventually expand to nominal caliber. In this investigation, postprocedure computed tomography (CT) was used to compare diameters of underdilated TIPSs and TIPSs expanded to a nominal diameter of 10 mm in 61 cases. The groups had comparable shunt diameters on post-TIPS imaging (9.8 mm vs 9.9 mm; P = .079), with similar incidences of hepatic encephalopathy (34% vs 20%; P = .372), indicating stent self-expansion over time, and bringing into question the advantages of underdilation for customization of shunt caliber.

  15. 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. PMID:26438449

  16. 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.

  17. 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

  18. State of the Art: Which Stent for Which Lesion in Peripheral Interventions?

    PubMed Central

    Henry, Michel; Klonaris, Christos; Amor, Max; Henry, Isabelle; Tzvetanov, Kiril

    2000-01-01

    Applications of endovascular procedures have been expanded dramatically throughout the human body for both occlusive and aneurysmal disease; arteries at the aortoiliac and femoropopliteal levels are no exception. Currently, interventional procedures are the 1st treatment option for most patients who have peripheral artery disease. Although balloon angioplasty alone offers good immediate and long-term results, the addition of stents has been proposed to improve the procedural success of angioplasty and extend its application to more patients with vascular disease. Stenting, however, is controversial. Its use is considered acceptable in the aortoiliac vessels but is more in dispute for the femoro-popliteal vessels. Moreover, the rapid development of endovascular stents for peripheral applications has made stent selection a complicated task for clinical practitioners. Many factors influence the type of stent selected; therefore, knowledge of the stents available—including various designs and individual properties—is mandatory. Appropriate selection depends on adequate preprocedural evaluation of the lesion; the choice of approach; the choice of primary versus selective stent placement; the location and characteristics of the lesion; the availability of stents in the intervention suite; and the experience of the operator. Several stents are now available, but they are not equivalent; it is important to select the stent that is best suited to the lesion. On the basis of our experience using different types of stents, as well as our review of the world medical literature, we summarize the properties of various stents and specific indications for their application. This report is intended for use as a practical guide to stent selection. PMID:10928499

  19. Nanomaterial coatings applied on stent surfaces.

    PubMed

    Bagheri, Mahsa; Mohammadi, Marzieh; Steele, Terry Wj; Ramezani, Mohammad

    2016-05-01

    The advent of percutaneous coronary intervention and intravascular stents has revolutionized the field of interventional cardiology. Nonetheless, in-stent restenosis, inflammation and late-stent thrombosis are the major obstacles with currently available stents. In order to enhance the hemocompatibility of stents, advances in the field of nanotechnology allow novel designs of nanoparticles and biomaterials toward localized drug/gene carriers or stent scaffolds. The current review focuses on promising polymers used in the fabrication of newer generations of stents with a short synopsis on atherosclerosis and current commercialized stents, nanotechnology's impact on stent development and recent advancements in stent biomaterials is discussed in context.

  20. Coronary Stents: The Impact of Technological Advances on Clinical Outcomes.

    PubMed

    Mennuni, Marco G; Pagnotta, Paolo A; Stefanini, Giulio G

    2016-02-01

    Percutaneous coronary interventions (PCI) were proposed in the late 1970s as an alternative to surgical coronary artery bypass grafting for the treatment of coronary artery disease. Important technological progress has been made since. Balloon angioplasty was replaced by bare metal stents, which allowed to permanently scaffold the coronary vessel avoiding acute recoil and abrupt occlusion. Thereafter, the introduction of early generation drug-eluting stents (DES) has significantly improved clinical outcomes, primarily by markedly reducing the risk of restenosis. New generation DES with thinner stent struts, novel durable or biodegradable polymer coatings, and new limus antiproliferative agents, have further improved upon the safety and efficacy profile of early generation DES. The present article aims to review the impact of technological advances on clinical outcomes in the field of PCI with coronary stents, and to provide a brief overview on clinical margins of improvement and unmet needs of available DES.

  1. 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.

  2. Percutaneous Treatment of Malignant Jaundice Due to Extrahepatic Cholangiocarcinoma: Covered Viabil Stent Versus Uncovered Wallstents

    SciTech Connect

    Krokidis, Miltiadis; Fanelli, Fabrizio; Orgera, Gianluigi; Bezzi, Mario; Passariello, Roberto; Hatzidakis, Adam

    2010-02-15

    To compare clinical effectiveness of Viabil-covered stents versus uncovered metallic Wallstents, for palliation of malignant jaundice due to extrahepatic cholangiocarcinoma, 60 patients were enrolled in a prospective and randomized study. In half of the patients a bare Wallstent was used, and in the other half a Viabil biliary stent. Patients were followed up until death. Primary patency, survival, complication rates, and mean cost were calculated in both groups. Stent dysfunction occurred in 9 (30%) patients in the bare stent group after a mean period of 133.1 days and in 4 (13.3%) patients in the covered stent group after a mean of 179.5 days. The incidence of stent dysfunction was significantly lower in the covered stent group (P = 0.046). Tumor ingrowth occurred exclusively in the bare stent group (P = 0.007). Median survival was 180.5 days for the Wallstent and 243.5 days for the Viabil group (P = 0.039). Complications and mean cost were similar in the two groups. Viabil stent-grafts proved to be significantly superior to Wallstents for the palliation of malignant jaundice due to extrahepatic cholangiocarcinoma, with comparable cost and complication rates. Appropriate patient selection should be performed prior to stent placement.

  3. 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.

  4. In vivo biocompatibility of a plasma-activated, coronary stent coating.

    PubMed

    Waterhouse, Anna; Wise, Steven G; Yin, Yongbai; Wu, Buchu; James, Barbara; Zreiqat, Hala; McKenzie, David R; Bao, Shisan; Weiss, Anthony S; Ng, Martin K C; Bilek, Marcela M M

    2012-11-01

    Bare metal and drug-eluting coronary stents suffer an inherent lack of vascular cell and blood compatibility resulting in adverse patient responses. We have developed a plasma-activated coating (PAC) for metallic coronary stents that is durable, withstands crimping and expansion, has low thrombogenicity and can covalently bind proteins, linker-free. This has been shown to enhance endothelial cell interactions in vitro and has the potential to promote biointegration of stents. Using the rabbit denuded iliac artery model, we show for the first time that PAC is a feasible coating for coronary stents in vivo. The coating integrity of PAC was maintained following implantation and expansion. The rate of endothelialization, strut coverage, neointimal response and the initial immune response were equivalent to bare metal stents. Furthermore, the initial thrombogenicity caused by the PAC stents showed a reduced trend compared to bare metal stents. This work demonstrates a robust, durable, non-cytotoxic plasma-based coating technology that has the ability to covalently immobilize bioactive molecules for surface modification of coronary stents. Improvements in the clinical performance of implantable cardiovascular devices could be achieved by the immobilization of proteins or peptides that trigger desirable cellular responses.

  5. Questioning Antiferromagnetic Ordering in the Expanded Metal, Li(NH3)4: A Lack of Evidence from μSR.

    PubMed

    Seel, Andrew G; Baker, Peter J; Cottrell, Stephen P; Howard, Christopher A; Skipper, Neal T; Edwards, Peter P

    2015-10-01

    We present the results of a muon spin relaxation study of the solid phases of the expanded metal, Li(NH3)4. No discernible change in muon depolarization dynamics is witnessed in the lowest temperature phase (≤25 K) of Li(NH3)4, thus suggesting that the prevailing view of antiferromagnetic ordering is incorrect. This is consistent with the most recent neutron diffraction data. Discernible differences in muon behavior are reported for the highest temperature phase of Li(NH3)4 (82-89 K), attributed to the onset of structural dynamics prior to melting. PMID:26722900

  6. [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. PMID:19348354

  7. Biodegradable polymeric stents for vascular application in a porcine carotid artery model: English version.

    PubMed

    Kischkel, S; Grabow, N; Püschel, A; Erdle, B; Kabelitz, M; Martin, D P; Williams, S F; Bombor, I; Sternberg, K; Schmitz, K-P; Schareck, W; Bünger, C M

    Obwohl die Entwicklung biodegradierbarer Polymerstents in den letzten Jahren große Fortschritte gemacht hat, verbleiben entscheidende noch zu lösende Probleme bestehen. Veränderungen im Design und in der chemischen Zusammensetzung sollen die Eigenschaften biodegradierbarer Stents optimieren und ihre Schwächen beseitigen.Der neue PLLA/P4HB-Stent konnte erfolgreich endovaskulär in die A. carotis communis von 10 Landschweinen implantiert werden, bei vergleichbaren mechanischen Eigenschaften zu 316L-Metallstents als Kontrollgruppe. 4 Wochen nach Implantation erfolgte eine Angio-CT zur Stenosegradbestimmung. Es zeigten sich deutlich höhere Stenosegrade in der PLLA/P4HB-Stent-Gruppe (52,05 ± 5,80 %) gegenüber der Metall-Stent-Gruppe (35,65 ± 3,72 %). Durch die orale Gabe von Atorvastatin konnte der distale Stenosegrad nach NASCET in der PLLA/P4HB-Stent-Gruppe (39,81 ± 8,57 %) auf das Niveau der Metall-Stent-Gruppe (44,21 % ± 2,34) gesenkt werden.Der PLLA/P4HB-Stent stellt einen vielversprechenden Ansatz zur Lösung der bestehenden Probleme beim Einsatz permanenter Stents dar. Nur wenn sich ein Stent vollständig auflöst, ist eine Heilung im Sinne einer Restitutio ad integrum möglich.

  8. Long-term effects of forgotten biliary stents: a case series and literature review

    PubMed Central

    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. PMID:25232385

  9. 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.

  10. Preliminary report on a new concept stent prototype designed for venous implant.

    PubMed

    Lugli, M; Maleti, O

    2015-08-01

    Venous obstruction at iliocaval level in both forms, primary and secondary, is a significant cause of severe chronic venous insufficiency. A new therapeutic approach to this pathology emerged with the introduction of stenting procedures that proved effective, leading to good long-term results. However, at present, the majority of implanted stents have been designed for arterial implant and this can pose a limit in particular districts. The purpose of this preliminary acute study was to verify the deliverability and safety of a new stent specially designed for venous-vessel implant. We assess the safety and deliverability of two braided, self-expanding, nickel-titanium stents (Jotec GmbH, Hechingen, Germany) specially designed for endovascular implant in veins. The two stents, despite being based on the same concept, have a different design: stent A presents a proximal tapering shape specially designed to reduce migration, while stent B does not. Both of them are enlarged at their distal extremity and present variable radial force the length of the stent itself, the said force becoming very high in the intermediate segment. Stents were implanted in the internal jugular vein of a sheep, showing optimal deliverability. The completion venography showed the migration of stent B into the right atrium. Stent A maintained its location, confirmed by intravascular ultrasound examination. No scaffolding effect was detected and an adequate adherence and adaptability to the vein wall was obtained. In conclusions, the stent A design matches the characteristics required by vein implants. Stability is achieved even where difficult anatomical conditions apply, such as in the jugular vein. Deployment is easy and precise in a given landing zone. Radial resistive force is very high, as required in specific vein districts, but is also associated with good flexibility. Following this preliminary acute report, further studies are required. PMID:24920424

  11. 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

  12. 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.

  13. 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. PMID:19128933

  14. 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

  15. Overlap stenting for in-stent restenosis after carotid artery stenting.

    PubMed

    Nishihori, Masahiro; Ohshima, Tomotaka; Yamamoto, Taiki; Goto, Shunsaku; Nishizawa, Toshihisa; Shimato, Shinji; Izumi, Takashi; Kato, Kyozo

    2016-05-01

    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

  16. 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.

  17. 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.

  18. A predictive study of the mechanical behaviour of coronary stents by computer modelling.

    PubMed

    Migliavacca, Francesco; Petrini, Lorenza; Montanari, Valeria; Quagliana, Isabella; Auricchio, Ferdinando; Dubini, Gabriele

    2005-01-01

    Intravascular stents are small tube-like structures expanded into stenotic arteries to restore blood flow perfusion to the downstream tissues. The stent expansion is an important factor to define the effectiveness of the surgical procedure: it depends on the stent geometry and includes large displacements and deformations, geometric and material non-linearity. Numerical analyses seem appropriate to study such a complex behaviour after a free stent expansion. In this study the finite element method (FEM) was applied to a new generation coronary stent. Results from computations were compared with those from a laboratory experiment in terms of radial expansion and elastic recoil. By means of a scanning electronic microscopy the area of plastic deformation were also detected and compared with those obtained in the numerical simulation. Matching between the different measurements was quite satisfactory even if some discrepancies were present due to the absence of the balloon in the numerical model. PMID:15604000

  19. Billowing Of Endologix Powerlink Stent Mimicking Endoleaks

    PubMed Central

    Wu, Alex; Karuppasamy, Karunakaravel; Wang, Weiping

    2016-01-01

    Introduction: Endoleaks remains one of the primary concerns of endovascular aortic aneurysm repair (EVAR) and is routinely followed with CT angiography (CTA). However, certain imaging findings can mimic endoleaks. Case Presentation: A 65-year-old woman who had endovascular aortic repair (EVAR) of an abdominal aortic aneurysm with Endologix Powerlink system developed marked new circumferential cauliflower-like bulging of contrast-filled sacs at mid-stent-graft with enlargement of the excluded aneurysm at 3-year follow-up. Conclusions: Considering the unique construct of the Powerlink stents, this is thought to represent aneurysmal degeneration of the outer fabric material from the metal struts and may potentially pressurize the excluded sac with risk for rupture. PMID:26949697

  20. Stent-Induced Esophageal Perforation: Treatment by Means of Placing a Second Stent After Removal of the Original Stent

    SciTech Connect

    Jung, Gyoo-Sik Park, Sung-Dal; Cho, Young Duk

    2008-05-15

    A case of esophageal perforation caused by a retrievable covered stent is presented. The distal end of the stent was protruding into the mediastinum, which made it impossible to negotiate a guidewire through the stent into the distal esophagus. The stent was successfully removed with use of a stent retrieval set, and esophageal perforation was treated with a second, covered stent with a good result. Fatality associated with this complication might be prevented by virtue of the retrievability of the stent we used. This result points to the effectiveness of a retrievable stent for the palliative treatment of malignant esophageal stricture.

  1. 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.

  2. 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.

  3. 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

  4. Effect of force-induced mechanical stress at the coronary artery bifurcation stenting: Relation to in-stent restenosis

    NASA Astrophysics Data System (ADS)

    Lee, Cheng-Hung; Jhong, Guan-Heng; Hsu, Ming-Yi; Liu, Shih-Jung; Wang, Chao-Jan; Hung, Kuo-Chun

    2014-05-01

    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.

  5. 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.

  6. 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. PMID:26364047

  7. 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.

  8. Delayed complications after flow-diverter stenting: reactive in-stent stenosis and creeping stents.

    PubMed

    Cohen, José E; Gomori, John Moshe; Moscovici, Samuel; Leker