scholarly journals Comparative Study of the Effect of Structural Parameters on the Flexibility of Endovascular Stent Grafts

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Ying Guan ◽  
Jing Lin ◽  
Zhihui Dong ◽  
Lu Wang
Keyword(s):  
Stent Graft ◽  
Structural Design ◽  
Structural Parameters ◽  
Apex Angle ◽  
Endovascular Stent ◽  
Spring Back ◽  
Stent Grafts ◽  
Stented Graft ◽  
The Relationship ◽  
Force Difference

The complication of stent graft-induced new entry (SINE) after thoracic endovascular aortic repair (TEVAR) may be caused by the spring-back force of both ends of the stent grafts. Spring-back force, which is exerted by the curvature and ends of stent grafts on the greater wall of the aorta, suggests poor flexibility. Research on stent graft flexibility via design optimization has been widely disregarded. Thus, this study investigates the relationship between stent graft structure and flexibility by measuring bending and spring-back forces. Stent spacing (5, 10, and 15 mm), apex angle (30° and 45°), and strut configuration (Z- and M-stented) were considered for the structural parameters. The overall tendency of spring-back and bending forces was similar. The stent graft with 15 mm spacing attained the lowest force level. The force difference between samples with 30° and 45° apex angles became prominent as the curving angle increased. The sample with 45° stent apex attained low force value. The Z-stented graft obtained a lower force than the M-stented graft with the same number of struts per hoop. Consequently, optimal flexibility was obtained when the structural design was characterized by long stent spacing, big stent apex angle, and Z-type strut configuration.

Endovascular stent-graft treatment for graft-vein anastomotic stenosis in haemodialysis patients with arteriovenous grafts

VASA ◽  
2015 ◽  
Vol 44 (6) ◽  
pp. 466-472 ◽  
Author(s):  
Chia-Hsun Lin ◽  
Yen-Yang Chen ◽  
Chai-Hock Chua ◽  
Ming-Jen Lu
Keyword(s):  
Risk Factors ◽  
Stent Graft ◽  
Target Lesion ◽  
Primary Patency ◽  
Anastomotic Stenosis ◽  
Secondary Patency ◽  
Endovascular Stent ◽  
Stent Grafts ◽  
Venous Anastomosis ◽  
Arteriovenous Grafts

Abstract. Background: In this study, we investigated the patency of endovascular stent grafts in haemodialysis patients with arteriovenous grafts, the modes of patency loss, and the risk factors for re-intervention. Patients and methods: Haemodialysis patients with graft-vein anastomotic stenosis of their arteriovenous grafts who were treated with endovascular stent-grafts between 2008 and 2013 were entered into this retrospective study. Primary and secondary patency, modes of patency loss, and risk factors for intervention were recorded. Results: Cumulative circuit primary patency rates decreased from 40.0 % at 6 months to 7.3 % at 24 months. Cumulative target lesion primary patency rates decreased from 72.1 % at 6 months to 22.0 % at 24 months. Cumulative secondary patency rates decreased from 81.3 % at 12 months to 31.6 % at 36 months. Patients with a history of cerebrovascular accident had a significantly higher risk of secondary patency loss, and graft puncture site stenosis jeopardised the results of stent-graft treatment. Conclusions: Our data can help to improve outcomes in haemodialysis patients treated with stent-grafts for venous anastomosis of an arteriovenous graft.

scholarly journals Endovascular repair of aortic aneurysm: Preliminary results

2009 ◽  
Vol 137 (1-2) ◽  
pp. 10-17 ◽  
Author(s):  
Lazar Davidovic ◽  
Momcilo Colic ◽  
Igor Koncar ◽  
Dejan Markovic ◽  
Dusan Kostic ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Stent Graft ◽  
Endovascular Aneurysm Repair ◽  
Aortic Aneurysms ◽  
Endovascular Stent ◽  
Stent Grafts ◽  
Graft Thrombosis ◽  
Abdominal Aortic

Introduction. Endovascular aneurysm repair (EVAR) has been introduced into clinical practice at the beginning of the 90's of the last century. Because of economic, political and social problems during the last 25 years, the introduction of this procedure in Serbia was not possible. Objective. The aim of this study was to present preliminary experiences and results of the Clinic for Vascular Surgery of the Serbian Clinical Centre in Belgrade in endovascular treatment of thoracic and abdominal aortic aneurysms. Methods. The procedure was performed in 33 patients (3 female and 30 male), aged from 42 to 83 years. Ten patients had a descending thoracic aorta aneurysm (three atherosclerotic, four traumatic - three chronic and one acute as a part of polytrauma, one dissected, two penetrated atherosclerotic ulcers), while 23 patients had the abdominal aortic aneurysm, one ruptured and two isolated iliac artery aneurysms. The indications for EVAR were isthmic aneurismal localisation, aged over 80 years and associated comorbidity (cardiac, pulmonary and cerebrovasular diseases, previous thoracotomy or multiple laparotomies associated with abdominal infection, idiopatic thrombocitopaenia). All of these patients had three or more risk factors. The diagnosis was established using duplex ultrasonography, angiography and MSCT. In the case of thoracic aneurysm, a Medtronic-Valiant? endovascular stent graft was implanted, while for the abdominal aortic aneurysm Medtronic-Talent? endovascular stent grafts with delivery systems were used. In three patients, following EVAR a surgical repair of the femoral artery aneurysm was performed, and in another three patients femoro-femoral cross over bypass followed implantation of aortouniiliac stent graft. Results. During procedure and follow-up period (mean 1.6 years), there were: one death, one conversion, one endoleak type 1, six patients with endoleak type 2 that disappeared during the follow-up period, one early graft thrombosis. No other complications, including aneurysm expansion, collapse, deformity and migration of the endovascular stent grafts, were registered. Conclusion. According to all medical and economic aspects, we recommend EVAR to treat acute traumatic thoracic aortic aneurysm, as well as in elderly and high-risk patients with abdominal or thoracic aneurysms, when open surgery is related to a significantly higher mortality and morbidity.

Development of an In Vitro Porcine Aorta Model to Study the Stability of Stent Grafts in Motor Vehicle Accidents

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Kurosh Darvish ◽  
Mehdi Shafieian ◽  
Vasily Romanov ◽  
Vittorio Rotella ◽  
Michael D. Salvatore ◽  
...  
Keyword(s):  
Stent Graft ◽  
Motor Vehicle ◽  
Motor Vehicle Accidents ◽  
Aortic Aneurysms ◽  
Endovascular Stent ◽  
Stent Grafts ◽  
Vehicle Accidents ◽  
Impact System ◽  
The Stability

Endovascular stent grafts for the treatment of thoracic aortic aneurysms have become increasingly utilized and yet their locational stability in moderate chest trauma is unknown. A high speed impact system was developed to study the stability of aortic endovascular stent grafts in vitro. A straight segment of porcine descending aorta with stent graft was constrained in a custom-made transparent urethane casing. The specimen was tested in a novel impact system at an anterior inclination of 45deg and an average deceleration of 55G, which represented a frontal automobile crash. Due to the shock of the impact, which was shown to be below the threshold of aortic injury, the stent graft moved 0.6mm longitudinally. This result was repeatable. The presented experimental model may be helpful in developing future grafts to withstand moderate shocks experienced in motor vehicle accidents or other dynamic loadings of the chest.

Endovascular Stent-Graft in Abdominal Aortic Aneurysms: The Relationship between Patent Vessels that Arise from the Aneurysmal Sac and Early Endoleak

Radiology ◽  
2001 ◽  
Vol 218 (1) ◽  
pp. 176-182 ◽  
Author(s):  
Chieh-Min Fan ◽  
Elizabeth A. Rafferty ◽  
Stuart C. Geller ◽  
John A. Kaufman ◽  
David C. Brewster ◽  
...  
Keyword(s):  
Stent Graft ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Endovascular Stent ◽  
Endovascular Stent Graft ◽  
Abdominal Aortic ◽  
The Relationship

Penetration Mechanics of Endovascular Stent Graft Barbs in Aortic Tissue

2011 ◽  
Author(s):  
Kathleen Lin ◽  
Benjamin Berkowitz ◽  
Madhavan L. Raghavan
Keyword(s):  
Stent Graft ◽  
Aortic Wall ◽  
Soft Tissues ◽  
The Body ◽  
Aortic Aneurysms ◽  
Fixation Strength ◽  
Aortic Tissue ◽  
Endovascular Stent ◽  
Penetration Mechanics ◽  
The Relationship

Endovascular stent grafts with barbs — tiny needle-like pins that provide active fixation — are increasingly used for treating aortic aneurysms and dissections. Characterization of barb penetration mechanics may help improve stent-graft designs. Barb angle varies among manufacturers (10–50°). But little is known regarding aortic wall penetration characteristics in relationship to barb angle. There is a body of work on needle insertion properties such as insertion forces into soft tissues. However, there have not been specific studies involving the aorta and the relationship between entry angle and entry force. Kratzberg et al. [1,2] demonstrated that barb angle was closely related to penetration angle and that lower angles between the barb and the body of the aortic stent-graft resulted in better penetration probability and fixation strength in the aortic wall. In order to assess why lower barb angles (i.e., barb axis closer to the graft axis) resulted in better penetration, this study investigates the relationship between barb penetration angle and aortic tissue entry force and compared it to a homogeneous control membrane made of silicone.

Intravascular Ultrasound in Endovascular Stent-Grafts for Peripheral Aneurysm: A Clinical Study

1998 ◽  
Vol 5 (2) ◽  
pp. 106-112 ◽  
Author(s):  
Marc RHM van Sambeek ◽  
Elma J. Gussenhoven ◽  
Hans van Overhagen ◽  
Jan Honkoop ◽  
Aad van der Lugt ◽  
...  
Keyword(s):  
Intravascular Ultrasound ◽  
Stent Graft ◽  
Endovascular Stent ◽  
Stent Grafts ◽  
Stent Grafting ◽  
Graft Stenosis ◽  
Graft Rupture ◽  
Initial Procedure ◽  
Peripheral Aneurysms ◽  
Selection Of

Purpose: To evaluate the potential diagnostic information of intraprocedural intravascular ultrasound (IVUS) in patients undergoing endovascular stent-grafting for peripheral aneurysm. Methods: IVUS was used in 17 patients preprocedurally to measure the diameter of the proximal and distal neck and the length of the aneurysm. Balloon and stent-graft sizes were selected based on these measurements. Following stent-graft deployment, angiography and IVUS were used to document stent apposition and the configuration and diameter of the stent-graft. Results: Stent-graft insertion was considered successful in 8 patients based on angiography and IVUS images. In 9 others, both imaging modalities showed inadequate results, necessitating 12 additional procedures: balloon angioplasty for stent-graft stenosis (2) and inadequate stent-graft apposition (1); an additional stent-graft (4); an extra stent (1); thrombectomy (2); and conversion (2) for inadequate stent-graft position and a graft rupture. In these patients, intraprocedural IVUS was superior to angiography in contributing vital information to aid in the selection of the additional interventions. Conclusions: During management of peripheral aneurysms with endovascular stent-grafts, IVUS monitoring was a useful adjunct when the initial procedure was unsatisfactory and/or when intraprocedural angiographic studies were inconclusive.

Utilization of stent grafts in the management of arteriovenous access pseudoaneurysms

Vascular ◽  
2017 ◽  
Vol 26 (4) ◽  
pp. 368-371 ◽  
Author(s):  
Afsha Aurshina ◽  
Anil Hingorani ◽  
Natalie Marks ◽  
Enrico Ascher
Keyword(s):  
Stent Graft ◽  
Primary Patency ◽  
Chronic Hemodialysis ◽  
Endovascular Stent ◽  
Technical Success ◽  
Stent Grafts ◽  
Clinical Safety ◽  
Endovascular Stent Graft ◽  
Technical Success Rate ◽  
Arteriovenous Access

Objective Endovascular stent graft repair for exclusion of pseudoaneurysm is currently being explored to replace open surgical repair as current management. The objective of the study was to evaluate the clinical safety and efficacy of endovascular stent graft intervention in pseudoaneurysms complicating arteriovenous reconstructions in patients on chronic hemodialysis. Methods A retrospective analysis of all pseudoaneurysms treated with stent grafts at our institution over a period of five years was performed. The indications for endovascular intervention included bleeding from the pseudoaneurysm, infection, and significant skin compromise overlying the pseudoaneurysm or combination of the above. The rates of technical success, complication, and primary patency were measured at one-week, one-month, and six-month follow-up. Results A total of 33 endovascular stent graft interventions in 29 patients were performed for the treatment of pseudoaneurysms. The average age of patients was 68 years (range 31–90 years), with 13 female. Diabetes and hypertension were present in 15 and 22 patients, respectively. In eight patients, there was evidence of active infection at the fistula site. The choice of stent grafts include Viabahn ( n = 31), Wallgraft ( n = 1), and i-Cast ( n = 1). The initial technical success rate was 94%. The two failed interventions included occlusion of inflow artery with immediate conversion to open procedure ( n = 1) and incomplete pseudoaneurysm exclusion ( n = 1). Primary patency at one month and six months was 83 and 60%, respectively. An additional balloon angioplasty of outflow tract or central stenosis was performed in 18 cases (54%). The explanation of stent grafts due to persistent or recurrent bacteremia/site infection was required in four out of eight patients. The average time to explanation was 93 days (range 6–204 days). Conclusion The stent graft implantation is a safe, minimally invasive and efficient way to control and manage arteriovenous accesses with pseudoaneurysms. In the presence of infection, this approach may be less durable.

Treatment of Thoracic Aortic Dissection with Stent-Grafts: Midterm Results

2002 ◽  
Vol 9 (6) ◽  
pp. 817-821 ◽  
Author(s):  
Won-Heum Shim ◽  
Bon-Kwon Koo ◽  
Young-Sup Yoon ◽  
Donghoon Choi ◽  
Yangsoo Jang ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Stent Graft ◽  
False Lumen ◽  
Endovascular Stent ◽  
Stent Grafts ◽  
Endovascular Stent Graft ◽  
Thoracic Aortic Dissection ◽  
Stent Graft Implantation ◽  
Graft Implantation

Purpose: To evaluate the early and midterm outcomes after stent-graft implantation for dissection in the descending thoracic aorta. Methods: Sixteen custom-made endovascular stent-grafts were implanted in 15 patients (10 men; mean age 55.9 ± 13.7 years, range 32–82) with descending thoracic aortic dissection. Indications for stent-graft implantation were persistent symptoms unresponsive to medical treatment or progressive enlargement of the false lumen. Clinical and imaging surveillance with computed tomography was performed within 1 month of the procedure and at 3 to 6-month intervals in follow-up. Results: Endovascular stent-graft implantation at the target site was successful in 14 (93%) patients; 1 device migrated, leaving the false lumen open to flow in the failed case. One (7%) patient who was treated emergently for rupture died suddenly 2 days after the procedure. Over an average follow-up of 31.5 ± 23.8 months, 1 (7%) patient died and 2 (14%) patients underwent surgical treatment due to recurrent dissection. The remaining 10 patients showed complete thrombosis of the false lumen; in 3, the false lumen completely resolved. Conclusions: Endovascular stent-graft implantation in descending thoracic aortic dissection is a feasible, safe, and effective treatment modality. However, further studies are necessary in a greater number of patients to determine if wider application of this minimally invasive procedure is justified.

scholarly journals A Miniature Four-Channel Ion Trap Array Based on Non-silicon MEMS Technology

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 831
Author(s):  
Qi Zhang ◽  
Xichi Lu ◽  
Ting Chen ◽  
Yu Xiao ◽  
Rujiao Yao ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Structural Design ◽  
High Performance ◽  
Extraction Efficiency ◽  
Ion Trap ◽  
Structural Parameters ◽  
Mass Resolution ◽  
Miniature Mass Spectrometer ◽  
Mems Technology ◽  
The Relationship

With the increasing application field, a higher requirement is put forward for the mass spectrometer. The reduction in size will inevitably cause a loss of precision; therefore, it is necessary to develop a high-performance miniature mass spectrometer. Based on the researches of rectangular ion trap, the relationship between mass resolution and structural parameters of the ion trap array was analyzed by further simulation. The results indicate that, considering the balance of mass resolution and extraction efficiency, the preferable values for the field radius of exit direction y0 and ion exit slot width s0 are 1.61 mm and 200 μm, respectively. Afterwards, a miniature four-channel ion trap array (MFITA) was fabricated, by using MEMS and laser etching technology, and mass spectrometry experiments were carried out to demonstrate its performance. The mass resolution of butyl diacetate with m/z = 230 can reach 324. In addition, the consistency of four channels is verified within the error tolerance, by analyzing air samples. Our work can prove the correctness of the structural design and the feasibility of MEMS preparation for MFITA, which will bring meaningful guidance for its future development and optimization.

Infection of endovascular abdominal aortic aneurysm stent graft after urosepsis: case report and review of the literature

Vascular ◽  
2012 ◽  
Vol 21 (1) ◽  
pp. 10-13
Author(s):  
H T C Veger ◽  
P Ph Hedeman Joosten ◽  
S R Thoma ◽  
M J T Visser
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Stent Graft ◽  
Open Repair ◽  
Graft Infection ◽  
Endovascular Stent ◽  
Review Of The Literature ◽  
Stent Grafts ◽  
Abdominal Aneurysm ◽  
Abdominal Aortic

Infection of endovascular abdominal aneurysm stent grafts is an uncommon but known complication. Inoculation with bacteria of the endovascular abdominal aneurysm stent graft during the actual implantation, in the periprocedural hospitalization or later due to an aortoenteric fistula, has been described in the literature. We report a case of endovascular abdominal aortic aneurysm stent graft infection occurring 40 months after implantation in a patient doing well up to an episode of urosepsis. In conclusion, we postulate that poor intraluminal healing of stent grafts, as observed in several explant studies, may result in a higher susceptibility to episodes of bacteremia than prosthetic vascular grafts inserted during open repair. We therefore consider the administration of prophylactic antibiotics in patients with endovascular stent grafts during periods with a likelihood of bacteremia.

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