Stent Kinking Research Articles

Analysis of Closed-Cell Intracranial Stent Characteristics Using Cone-Beam Computed Tomography With Contrast Material

The intracranial nitinol stent named the Enterprise Vascular Reconstruction Device has poor radiographic visibility. The characteristics of closed-cell intracranial stents were investigated and the efficacy of intraoperative stent visualization examined with the 80 kV high-resolution XperCT protocol, which is a flat detector C-arm volume acquisition functionality system integrated with the angiography equipment. We treated 39 aneurysms with stent-assisted coil embolization. The aneurysms were located on the internal carotid artery in 24 cases, the anterior communicating artery (AcomA) in three, the basilar artery (BA) in 10, and the vertebral artery in two. Intraoperative 80 kV XperCT was performed in all cases after deposition of the stent. We evaluated the coverage of the aneurysm neck, incomplete stent apposition (ISA), and shift of vessels. Accurate stent visualization was achieved in 29 of the 39 cases without coil and delivery wire artifact. Coverage of the aneurysm neck succeeded in 28 cases; there was one case of BA top Y-configuration stenting in which the stent was dislocated into the aneurysm. ISA was detected in nine cases, including seven kinks and one flattening in the carotid siphon and one kink in the BA top. We detected linearization of vessels due to stent deployment in three AcomA cases and three BA top cases. We conclude that intraoperative 80 kV XperCT is an efficient modality for the evaluation of ISA. Stent kinking in the carotid siphon and linearization in distal vessels can be detected with this protocol.

TCT-189 Plaque Excision as a Treatment Option for Popliteal Atherosclerotic Disease: 1-Year Results from the DEFINITIVE LE Study

The popliteal artery is often referred to as the “no-stent zone” due to concern for stent fracture, kinking or occlusion secondary to the constant torsion, compression and flexion applied to the vessel. The DEFINITIVE LE study was a global study that assessed the effectiveness of atherectomy

Covered stents versus uncovered stents for the palliation of malignant extrahepatic biliary obstruction caused by direct tumor invasion: a cohort comparative study

Biliary stenting is a well-established palliative treatment in patients with unresectable malignant biliary strictures. The aim of the present study was to compare clinical outcomes of covered and uncovered stents in patients with malignant extrahepatic biliary obstruction caused by direct tumor invasion. Patients diagnosed with malignant extrahepatic biliary obstruction caused by direct tumor invasion were enrolled in this study. Of these patients, 37 received ePTFE-covered stent placement and were prospectively studied, and 47 received uncovered stent placement and were retrospectively studied. The technical success rate, tumor ingrowth rate, complication rate, stent patency, and patient survival were evaluated for both groups. Stent placement was successful in all cases except one in the covered group due to stent kinking. Tumor ingrowth occurred exclusively in the uncovered group. No significant differences were observed for the complication rate and patient survival between the two groups. Three patients in the covered group experienced stent migration, whereas no patients did in the uncovered group. A significant difference was found regarding stent patency, which was greater for the covered group compared to the uncovered group. The placement of ePTFE-covered stents for the treatment of malignant biliary obstruction caused by direct tumor invasion was a safe and an effective method characterized by greater stent patency.

Su1438 Efficacy and Safety of a Newly Developed Fully Covered Biliary Metallic Stent in Comparison With the Partially Covered WallFlex Biliary RX Stent for Unresectable Malignant Biliary Stricture

Su1438 Efficacy and Safety of a Newly Developed Fully Covered Biliary Metallic Stent in Comparison With the Partially Covered WallFlex Biliary RX Stent for Unresectable Malignant Biliary Stricture Takahisa Ogawa, Kei Ito, Naotaka Fujita, Yutaka Noda, Go Kobayashi, Takashi Obana, Jun Horaguchi, Shinsuke Koshita, Yoshihide Kanno Department of Gastroenterology, Sendai City Medical Center, Sendai, Japan Background and aim: Endoscopic self-expandable metallic stent (SEMS) placement is widely accepted as a palliative therapy in patients with unresectable malignant biliary stricture. Although a covered SEMS has been reported to have a longer stent patency than an uncovered SEMS, complications such as stent migration and kinking of the bile duct can occur after deployment. A newly developed fully covered biliary metallic stent (ZEOSTENT Covered (ZEO), Zeon Medical Inc., Tokyo, Japan) which has an uneven outer surface, a low shortening ratio, and a low axial force might reduce such complications. The aim of this study was to evaluate the efficacy and safety of this new covered biliary stent in comparison with the partially covered WallFlex Biliary RX Stent (Wall) (Boston Scientific, Co., Ltd., Natic, MA, USA). Patients and methods: Between March 2010 and November 2010, endoscopic placement of a ZEO was performed in 24 patients (mean age, 77 10 yrs; 10 males, 14 females) with unresectable malignant biliary stricture. Fifteen patients had pancreatic cancer, 4 had bile duct cancer, 2 had gallbladder cancer, 2 had ampullary cancer and 1 had lymph node metastases from other cancers. Main outcome measurements were success rate of the procedure, early complications, late complications, and stent patency. Early complications were defined as those which occurred within 3 days after stent placement. Such data were compared with those of 24 patients (mean age, 75 12 yrs; 13 males, 11 females) who had undergone endoscopic placement of a Wall between April 2009 and July 2010. Results: Mean follow-up duration of the ZEO group and the Wall group were 77 days and 124 days, respectively (P 0.024). Stent placement was successful and improvement of jaundice was obtained in all patients of both groups. ZEO and Wall were transpapillarily placed in 18 and 22 patients, respectively. Transduodenal and transgastric stent placement utilizing the endosonography-guided biliary drainage route was performed in 5 and 2 patients, respectively. Early complications occurred in 1 patient in the ZEO group (pancreatitis, 1) and in 4 in the Wall group (pancreatitis, 3; cholecystitis,1) (P 0.17). Late complications occurred in 5 patients of the ZEO group (stent occlusion, 4; stent migration, 1; cholecystitis, 1) and in 6 of the Wall group (stent occlusion, 1; stent migration, 2; cholecystitis, 3; cholangitis without stent occlusion, 1) (P 1.00). In 3 cases of the ZEO group, tumor ingrowth occurred due to breakage of the cover, whereas there were no such cases in the Wall group. Mean stent patency duration of the ZEO group and the Wall group were 243 days and 382 days, respectively (P 0.20). Conclusion: The short-term efficacy and safety of ZEO were comparable with those of Wall. However, improvement of the cover of the ZEO is indispensable for prevention of tumor ingrowth.

A Multicenter Prospective Study of the Short-Term Outcome of a Newly Developed Partially Covered Self-Expandable Metallic Biliary Stent (WallFlex®)

Self-expandable metallic stent (SEMS) placement is a widely used, effective therapy for unresectable malignant stricture of the lower bile duct. We evaluated the short-term outcome of the newly developed WallFlex(®) Biliary RX Partially Covered Stent in patients with malignant lower and middle biliary stricture in five tertiary referral centers. The subjects of this study were 52 patients in whom WallFlex(®) Biliary RX Stents were inserted into the bile duct for malignant stenosis of the middle and lower bile duct at five medical facilities between April 2009 and November 2009. The stent placement success rate was 100%. Effective biliary decompression was achieved in all patients. The incidence of early complications was 7.7% (4/52). Stent occlusion occurred in two patients (3.8%) (one dislocation, one migration); cholecystitis occurred in two patients (3.8%). Neither acute pancreatitis nor stent kinking in the bile duct occurred. The present results revealed that the new WallFlex(®) Biliary RX Partially Covered SEMSs were useful for the short-term relief of biliary obstruction due to unresectable distal biliary malignancies.

Technical Development and Initial Animal Experience With a Novel, Uncovered, Self-Expanding, Highly Flexible Aortic Stent With Improved Side Branch Access

To present a novel, uncovered, self-expanding aortic stent for use as a thoracoabdominal stent-graft extension to improve distal flow in aortic dissections complicated by malperfusion syndrome and to enhance the remodeling process in the abdominal aorta after thoracic endovascular aortic repair. This aortic prosthesis is a laser cut, self-expanding nitinol stent that is designed to provide an optimal balance between radial support and flexibility to negotiate tortuous arterial anatomy. Undulating circumferential rings provide radial force, while flexibility is achieved through the shape and configuration of the longitudinal connectors that extend from the valley of one ring to the offset peak of the next ring. Delivery and deployment characteristics, in vivo flexibility of the stent, and side branch accessibility through the bare stent struts were evaluated in 4 anesthetized domestic swine weighing 68 to 73 kg. All 11 attempted stent implantations were successful in the 4 pigs using a retrograde transiliac access. The stents were positioned and deployed exactly at the intended target locations and conformed well to the aortic anatomy, even in the tortuous aortic arch, with no evidence of stent kinking or collapse. Overall, 21 major aortic side branches were intentionally covered with the bare stent struts; perfusion was not impaired in any branch vessel. Superselective catheterization of the side branches with coronary guiding catheters through the stent struts was possible for all vessels, as was side branch stenting in 3/3 attempts. This initial feasibility study demonstrates the ability to deploy this novel self-expanding aortic stent in pigs. The high flexibility of the stent allowed conformability with tortuous aortic anatomy. Access to side branches overstented with bare stent struts was excellent. Clinical evaluation of the device is planned for the near future.

Analysis of ureteric stent kinking forces: the role of curvature in stent failure

To further characterize the kinking forces and degree of curvature that result in failure of various stents, as malignant obstruction of the ureter causes failure of about half of ureteric stents. Several stents (Silhouette 4.6 F and 6 F, Applied Medical, Rancho Santa Margarita, CA; Sof-Curl Tecoflex 6 F, Gyrus ACMI, Southborough, MA; Polaris Ultra 6 and 7 F, and Percuflex 6, 7 and 8 F stents, Boston Scientific, Natick, MA, USA) were tested. The amount of force necessary to result in kinking of the stent was measured, and the degree of curvature at failure was calculated for each stent. The Silhouette 4.6 and 6 F stents were the most resistant to failure by kinking and curvature. In general, smaller stents allowed more curvature before failing than their larger counterparts. The greater allowable curvature and resistance to kinking achieved by the Silhouette ureteric stents might result in fewer stent failures in cases of malignant obstruction or other retroperitoneal processes.

Early complication after hybrid thoracic aortic aneurysm repair

This brief report describes an unusual hybrid approach complication of aortic arch disease. An acute stent kinking in the first post-operative day promoted ventricular fibrillation and death. Adequate oversizing was achieved and intraoperative angiogram showed no proximal or distal leaks. Unfavorable outcomes are highly under-reported and describing complications are a key instrument to improve this technique.

Spatio-temporal changes and migration of stent grafts after endovascular aortic aneurysm repair

In this paper we present an approach to analyse the migration of stent grafts after endovascular aortic aneurysm repair. Stent graft migration and kinking or buckling of the graft can cause the perilous risk of rupture. Our approach allows describing the occurring movements quantitatively towards the aim to find common patterns related to different endograft devices or to dangerous changes in morphology. We proceed by defining the spinal canal as reference system and by investigating the movements of the graft relative to it. Here, we segment the spinal canal as well as the stent graft at different time points and we apply a point set registration algorithm in order to calculate the transformation to the spinal canal reference system and to determine the occurring motion of the stent. First results illustrate that essentially rigid motion occurs in case of thoracic aortic aneurysms.