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Characterization of Partially Covered Self-Expandable Metallic Stents for Esophageal Cancer Treatment: In Vivo Degradation.

ABSTRACT: Partially covered self-expandable metallic esophageal stent (SEMS) placement is the most frequently applied palliative treatment in esophageal cancer. Structural characterization of explanted 16 nitinol-polyurethane SEMS (the group of 6 females, 10 males, age 40-80) was performed after their removal due to dysfunction. The adverse bulk changes in the polymer structure were identified using differential scanning calorimetry (DSC), differential mechanical thermal analysis (DMTA), and attenuated total reflectance infrared spectroscopy (ATR-IR) and discussed in terms of melting point shift (9 °C), glass-transition shift (4 °C), differences in viscoelastic behavior, and systematic decrease of peaks intensities corresponding to C-H, C═O, and C-N polyurethane structural bonds. The scanning electron and confocal microscopic observations revealed all major types of surface degradation, i.e., surface cracks, peeling off of the polymer material, and surface etching. The changes in the hydrophobic polyurethane surfaces were also revealed by a significant decrease in wettability (74°) and the corresponding increase of the surface free energy (31 mJ/m²). To understand the in vivo degradation, the in vitro tests in simulated salivary and gastric fluids were performed, which mimic the environments of proximal and distal ends, respectively. It was concluded that the differences in the degradation of the proximal and distal ends of prostheses strongly depend on the physiological environment, in particular stomach content. Finally, the necessity of the in vivo tests for SEMS degradation is pointed out.

SUBMITTER: Chytrosz P

PROVIDER: S-EPMC8045022 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Self-expandable metallic stents (SEMSs) have been widely used in the treatment of malignant central airway obstruction. However, few reports focus on the treatment of atelectasis and how to estimate the prior probability of success via SEMSs placement, This current study aimed to study the safety and effectiveness of SEMSs for the treatment of obstructive atelectasis, and the value of preoperative CT enhancement for ventilation of atelectasis via SEMSs placement. A total of 35 patients with obstructive atelectasis (29 male and 6 female) was included from February 2012 to March 2018. The procedures were performed under fluoroscopic guidance, and bronchoscopic laser resection was performed for severe restenosis cases after SEMSs 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. Thirty-eight SEMSs were successfully implanted in 34 patients, included 29 Y type tracheal stents, 4 small y stents, and 5 straight airway stents. After stenting, 26 cases showed full ventilation, and 3 cases were partially ventilated. The technical success and clinical success was 97.1% and 82.9%, respectively. A higher maximum enhancement CT value was found in patients with full ventilation. Mean follow-up time was 18.8 ± 4.0 months. Eight cases showed restenosis and received endoscopic laser resection, included 1 case underwent removal and 3 cases received second stenting. There were 2 cases of perioperative non-operative death, and 11 cases of post-discharge death (2 cardiac deaths and 9 malignant tumors). The survival rates of 3 months, 1 year and 2 years were 78.6%, 58.5% and 58.5%, respectively. In conclusion, SEMSs placement is safe and effective for obstructive atelectasis, and the preoperative CT enhancement played an important role in estimating the prior probability of success in the treatment of atelectasis via SEMSs placement.

Project description:AimTo compare the efficacy of using covered self-expandable metal stents (CSEMSs) and uncovered self-expandable metal stents (UCSEMSs) to treat objective jaundice caused by an unresectable malignant tumor.MethodsWe performed a comprehensive electronic search from 1980 to May 2015. All randomized controlled trials comparing the use of CSEMSs and UCSEMSs to treat malignant distal biliary obstruction were included.ResultsThe analysis included 1417 patients enrolled in 14 trials. We did not detect significant differences between the UCSEMS group and the CSEMS group in terms of cumulative stent patency (hazard ratio (HR) 0.93, 95% confidence interval (CI) 0.19-4.53; p = 0.93, I2 = 0%), patient survival (HR 0.77, 95% CI 0.05-10.87; p = 0.85, I2 = 0%), overall stent dysfunction (relative ratio (RR) 0.85, M-H, random, 95% CI 0.57-1.25; p = 0.83, I2 = 63%), the overall complication rate (RR 1.26, M-H, fixed, 95% CI 0.94-1.68; p = 0.12, I2 = 0%) or the change in serum bilirubin (weighted mean difference (WMD) -0.13, IV fixed, 95% CI 0.56-0.3; p = 0.55, I2 = 0%). However, we did detect a significant difference in the main causes of stent dysfunction between the two groups. In particular, the CSEMS group exhibited a lower rate of tumor ingrowth (RR 0.25, M-H, random, 95% CI 0.12-0.52; p = 0.002, I2 = 40%) but a higher rate of tumor overgrowth (RR 1.76, M-H, fixed, 95% CI 1.03-3.02; p = 0.04, I2 = 0%). Patients with CSEMSs also exhibited a higher migration rate (RR 9.33, M-H, fixed, 95% CI 2.54-34.24; p = 0.008, I2 = 0%) and a higher rate of sludge formation (RR 2.47, M-H, fixed, 95% CI 1.36-4.50; p = 0.003, I2 = 0%).ConclusionsOur meta-analysis indicates that there is no significant difference in primary stent patency and stent dysfunction between CSEMSs and UCSEMSs during the period from primary stent insertion to primary stent dysfunction or patient death. However, when taking further management for occluded stents into consideration, CSEMSs is a better choice for patients with malignant biliary obstruction due to their removability.

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Characterization of Partially Covered Self-Expandable Metallic Stents for Esophageal Cancer Treatment: In Vivo Degradation.

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