• Journal of the Korean Society of Radiology
• /
• v.84 no.1
• /
• pp.197-211
• /
• 2023

Purpose To evaluate the circuit patency after nitinol bare-metal stent (BMS) placement according to the type of access and location of the stent in dysfunctional hemodialysis access. Materials and Methods Between January 2017 and December 2019, 159 patients (mean age, 64.1 ± 13.2 years) underwent nitinol BMS placement for dysfunctional access. The location of stents was as follows: 18 brachiocephalic vein, 51 cephalic arch, 40 upper arm vein, 10 juxta-anastomotic vein, 7 arteriovenous (AV) anastomosis, and 33 graft-vein (GV) anastomosis. Circuit patency was evaluated by the Kaplan-Meier method, and cox regression model. Results A total of 159 stents were successfully deployed in 103 AV fistula (AVF) and 56 AV graft (AVG). AVG showed lower primary and secondary patency at 12-months compared with AVF (primary patency; 25.0% vs. 44.7%; p = 0.005, secondary patency; 76.8% vs. 92.2%; p = 0.014). Cox regression model demonstrated poorer primary patency at 12 months after stenting in the cephalic arch and GV anastomosis compared with the other sites. Conclusion AVF showed better primary and secondary circuit patency at 12 months following the placement of BMS compared with AVG. Stents in the cephalic arch and GV anastomosis were associated with poorer primary patency at 12 months compared to those in other locations.

• Progress in Medical Physics
• /
• v.20 no.3
• /
• pp.139-144
• /
• 2009

Recently, the mathematical analysis of stent simulation has been improved, with the help of development of various tool which measure mechanical property and location of stent in artery. The most crucial part of the stent modeling is how to design ideal stent and to evaluate the interaction between stent and artery. While there has been great deal of researches on the evaluation of the expansion, stress distribution, deformation of the stent in terms of the various parameters, few verification through computer simulation has been performed about deformation and stress distribution of the stent. In this study, we have produced the corresponding results between experimental test using Universal Testing Machine and computer simulation for the ideal model of stent. Also, we have analyzed and compared stress distribution of stent in the cases of that with membrane and that without membrane. The results of this study would provide minimum change of plan and good quality for ideal stent replacing damaged artery through the analysis using computer simulation in the early stage of stent design.

• Clinical and Experimental Pediatrics
• /
• v.48 no.5
• /
• pp.512-517
• /
• 2005

Purpose : In adults, endoscopic tracheobronchial balloon dilatation and stenting have become valuable methods to establish and maintain an adequate airway lumen when tracheomalacia or neoplastic growth compromise the airways. But in children, only a few cases were reported due to technical problems. We report six children who were treated with stent implantation and describe the use and safety of airway stents. Methods : Six patients with severe airway obstruction were treated. We investigated the underlying medical problems, stenotic site, symptomatic improvement and complications, and the size and location of stent. Results : The median age of the six patients was 21 months. Three of them were mechanically ventilated and one had an endotracheal tube to maintain the patency of airway. Diagnoses were : congenital tracheal stenosis with or without bronchomalacia, granulation tissue formation after right upper lobectomy by bronchial carcinoid or after prolonged intubation, endobronchial tuberculosis, and airway compression by mediastinal undifferentiated sarcoma. Nitinol stents were implanted in the airway guided by bronchoscopy and fluoroscopy simultaneously. Three cases were placed in trachea, the others were in the bronchus. After stent implantation, all patients showed marked improvements of their airway obstructive symptoms. Four patients are doing well, although two expired due to underlying diseases. Four patients had granulation tissue formation around stents, but that was tolerable after removing the stent. Conclusion : We suggest that the use of expandible metallic stent implantation can offer safe therapeutic option even in extremely severe, life threatening and inoperable airway stenosis in children.

• Korean Journal of Radiology
• /
• v.2 no.3
• /
• pp.145-150
• /
• 2001

Objective: To investigate the effectiveness of the newly designed Niti-S stent in the management of iliac arterial stenoses and occlusions. Materials and Methods: Stenoses (n=25) or occlusions (n=5) in the iliac arteries of 25 patients (30 limbs) were treated. The site of the lesions was the common (n=15) or external (n=11) iliac artery, or both (n=4). Eight limbs were treated for diffuse disease, six for highly eccentric lesion, five for occlusive lesion, and 11 for failed angioplasty. Results: In all patients, technical success was achieved without major complications. One death, not procedure-related, occurred within 30 days. Ankle-brachial indexes improved from 0.63 0.30 to 0.99 0.21, and ischemic symptoms showed improvement in 22 patients (88%). Fontaine classifications before stenting, namely IIa(n=3), IIb(n=16), III(n=2), and IV(n=4) improved to I(n=17), IIa(n=5), and IV(n=3). Follow-up over a 27 (mean, 19.8 8)-month period showed that cumulative patency rates were 95.8% at 1 year and 86.2% at 2 and 3 years. No significant decrease in the mean ankle-brachial index was observed. Conclusion: The Niti-S stent appears to be a safe and effective device for the treatment of iliac stenoses and occlusions. These preliminary results require confirmation with a larger series.

• Journal of Chest Surgery
• /
• v.42 no.1
• /
• pp.53-58
• /
• 2009

Background: The goal of this study was to compare the patency and complications of femoropopliteal bypass with superficial femoral artery stenting for patients with atherosclerotic superficial femoral artery occlusive disease. Material and Method: Between July 2005 and July 2008, we reviewed 29 femoropopliteal bypass procedures (24 patients) with prosthetic grafts (the bypass group) and 19 superficial femoral artery stentings (15 patients) with nitinol stent (the stent group). There were 35 male patients (89.7%) and the mean age of the patients was 69.2 years (range: 48~84). The number of patients who had DM, hypertension and a smoking history was 25 patients (64.1%), 17 patients (43.6%) and 30 patients (76.9%), respectively. 23 (59.0%) patients had skin ulceration or tissue gangrene at admission. Result: There were 27 cases (93.0%) of TASC C&D lesion in the bypass group and 16 cases (84.2%) of TASC A&B lesion in the stent group. There were significant differences for the indications for a procedure between the two groups (p<0.01). The primary patency rates at 6 months, 12 months and 24 months were 91.9%, 79.7% and 79.7% for the bypass group and 93.3%, 86.2% and 86.2% for the stent group, respectively. There were no statistical difference between the two groups (p=0.48). Conclusion: There were no significant differences in the outcome between two groups. TASC C&D lesion and failed intervention therapy should be treated with femoropopliteal bypass surgery, and TASC A&B lesion and the high-risk patients should be treated with femoral artery stent insertion.