New approach to radial expansive force measurement of self expandable esophageal metal stents

In Vitro Evaluation of Mechanical Properties of Segmented Esophageal Self-Expandable Metal Stents: Innovative Test Methods Are Needed

Background: Self-expanding metal stents (SEMSs) in different geometric shapes are well established treatment options in diseases of the esophagus. Mechanical properties and stent design may have an impact on patient comfort, migration rate, and removability. In this in vitro study, we evaluated mechanical properties of three segmented SEMSs (segSEMSs) for the esophagus with regard to distinct stent sections. Materials and Methods: Radial forces were measured using a testing method distinguishing between circumferential radial and local radial force. The center parts of the segSEMSs were measured for circumferential radial forces without being affected by the flared ends. Axial forces were measured at 20° bending. Results: Circumferential radial force measurements over the full stent length showed substantial differences against measurements of the center parts of the stents as the flared ends falsify test results by up to 53%. Although circumferential radial forces of the center parts were about the same (<10% variances) for all segSEMSs, local radial forces showed considerable differences of up to 26%. One segSEMS showed high axial forces, whereas the other two only needed half of the force (up to 53%) to be bent to 20°. Conclusion: Flared ends of segSEMSs have a substantial impact on radial force measurements and therefore alter test results, confirmed by our separated center part test of segSEMSs. Our innovative setup whereby we compressed the stent in an asymmetric manner (local radial force) and evaluated sections of stents separately, indeed revealed differences to circumferential measurements, leading to a more in-depth knowledge of stent characteristics.

[Endoscopic management of complications after laparoscopic sleeve gastrectomy]

Laparoscopic sleeve gastrectomy (SG) is currently the most commonly performed standalone bariatric procedure worldwide. Gastric staple line leakage is the feared immanent complication of the operation, which is difficult to treat and often persists. This article presents the endoscopic treatment options for complications after laparoscopic SG, particularly the treatment of gastric staple line leakage. Most important for a successful treatment is the understanding of the underlying pathophysiological causes, the exact surgical comprehension of the procedure and advanced endoscopic skills. The choice of endoscopic intervention depends on the available strategies as well as on the skills of the executing endoscopist. Currently, internal drainage seems to be the most expedient method.

Optimal radial force and size for palliation in gastroesophageal adenocarcinoma: a comparative analysis of current stent technology

BACKGROUND

The optimal use of esophageal stents for malignant and benign esophageal strictures continues to be plagued with variability in pain tolerance, migration rates, and reflux-related symptoms. The aim of this study was to evaluate the differences in radial force exhibited by a variety of esophageal stents with respect to the patient's esophageal stricture.

METHODS

Radial force testing was performed on eight stents manufactured by four different companies using a hydraulic press and a 5000 N force gage. Radial force was measured using three different tests: transverse compression, circumferential compression, and a three-point bending test. Esophageal stricture composition and diameters were measured to assess maximum diameter, length, and proximal esophageal diameter among 15 patients prior to stenting.

RESULTS

There was a statistically significant difference in mean radial force for transverse compression tests at the middle (range 4.25-0.66 newtons/millimeter N/mm) and at the flange (range 3.32-0.48 N/mm). There were also statistical differences in mean radial force for circumferential test (ranged from 1.19 to 10.50 N/mm, p < 0.001) and the three-point bending test (range 0.08-0.28 N/mm, p < 0.001). In an evaluation of esophageal stricture diameters and lengths, the smallest median diameter of the stricture was 10 mm (range 5-16 mm) and the median proximal diameter normal esophagus was 25 mm (range 22-33 mm), which is currently outside of the range of stent diameters.

CONCLUSIONS

Tested stents demonstrated significant differences in radial force, which provides further clarification of stent pain and intolerance in certain patients, with either benign or malignant disease. Similarly, current stent diameters do not successfully exclude the proximal esophagus, which can lead to obstructive-type symptoms. Awareness of radial force, esophageal stricture composition, and proximal esophageal diameter must be known and understood for optimal stent tolerance.

Endoscopic management of difficult or recurrent esophageal strictures

Esophageal strictures are a common problem in gastroenterological practice. In general, the management of malignant or benign esophageal strictures is different and requires a different treatment approach. In daily clinical practice, stent placement is a commonly used modality for the palliation of incurable malignant strictures causing dysphagia, whereas, if available, intraluminal brachytherapy can be considered in patients with a good performance status. Recurrent dysphagia frequently occurs in malignant cases. In case of tissue in- or overgrowth, a second stent is placed. If stent migration occurs, the stent can be repositioned or a second (preferably partially covered) stent can be placed. Food obstruction of the stent lumen can be resolved by endoscopic cleansing. The cornerstone of the management of benign strictures is still dilation therapy (Savary-Gilliard bougie or balloon). There are a subgroup of strictures that are refractory or recur and an alternative approach is required. In order to prevent stricture recurrence, steroid injections into the stricture followed by dilation can be considered. In case of anastomotic strictures or Schatzki rings, incisional therapy is a safe method in experienced hands. Temporary stent placement is a third option before considering self-bougienage or surgery as a salvage treatment. In this review, the most frequently used endoscopic treatment modalities for malignant and benign stricture management will be discussed based on the available literature, and some practical information for the management in daily clinical practice will be provided.