Strecker stent in stenotic hemodialysis Brescia-Cimino arteriovenous fistulas

Flexible tantalum stents (Strecker) were used as an adjunct to percutaneous transluminal angioplasty (PTA) in the treatment of stenotic arterial or venous limbs of Brescia-Cimino hemodialysis fistulas. The diagnostic procedure was performed using retrograde fistulography. After PTA with unsatisfactory results, stents were placed in 5 patients with significant residual stenoses and poor fistula function. Within the mean follow-up period of 6.4 months (range 3–10 months) all fistulas were functioning. We conclude that Strecker stent is useful in the treatment of stenotic hemodialysis arteriovenous fistulas as an adjunct to PTA.     

Placement of venous stents: clinical experience with a self-expanding prosthesis.

A self-expanding vascular prosthesis was used to treat 20 venous stenoses or occlusions in 13 patients. The lesions were caused by tumor (n = 5), postoperative fibrous scars (n = 2), and chronic hemodialysis fistulas (n = 13). Follow-up ranged between 6 weeks and 53 months (mean follow-up, 14.9 months). Acute occlusion occurred in two stents, one within a tumor stenosis and one in a dialysis shunt after 3 days and 2 days, respectively. Balloon angioplasty, thrombolysis, and aspiration in the first case and balloon angioplasty and thrombolysis in the second case successfully restored patency. Definite occlusion occurred in these two patients after 8 weeks and 5 months, respectively. Ten secondary interventions were performed in three patients with 10 restenoses who had stenotic arm veins in chronic hemodialysis at presentation. Five of seven patients who received treatment for stenoses associated with hemodialysis underwent successful kidney transplantation 5-27 months after placement of vascular stents. Both patients who received treatment for benign strictures had patent stents at follow-up examinations performed at 45 and 53 months, respectively. Four of five stents placed for malignant stenoses were patent at venography (n = 3) or autopsy (n = 1).     

Comparison of SMART stent placement for arteriovenous graft salvage versus successful graft PTA

PURPOSE: To compare the SMART (shape memory alloy recoverable technology) stent with percutaneous transluminal angioplasty (PTA) alone in hemodialysis access venous stenoses. MATERIALS AND METHODS: A prospective, nonrandomized study was undertaken in 60 patients with dysfunctional polytetrafluoroethylene dialysis grafts. Indications for stent placement were acute PTA failure, rapid restenosis, and vessel perforation. The primary endpoint was improved graft patency in patients treated with stents compared with that in patients whose disease responded to PTA alone. The secondary endpoints were lower postprocedural midgraft pressures and similar complication rates compared with PTA alone. RESULTS: The key venous stenosis was at the graft-to-vein anastomosis in all but two patients. Thirty-five patients showed a response to PTA alone. Sixteen patients received stents for stenoses greater than 30% after angioplasty, six for rapidly recurrent stenosis, and three for venous rupture. Nine patients received stents across the level of the elbow joint. Stenosis after intervention was significantly less frequent in the stent group (7% vs 16%; P = .001), but the midgraft systolic pressure ratios did not significantly differ. The clinical success rates were 100% after stent implantation and 97% after PTA alone. Except for venous rupture, there were no procedure-related complications, and, excluding early graft thrombosis, there were no complications at 30 days. A single stent fracture was found on follow-up. The mean primary graft patency times were 5.6 months after PTA and 8.2 months after stent treatment (P = .050). When stents were placed across the level of the elbow joint, the mean primary graft patency time was 8.9 months. CONCLUSION: Implantation of the SMART stent is safe and effective for the treatment of residual or rapidly recurrent dialysis access venous stenoses and is associated with better patency than PTA alone.     

Balloon angioplasty of venous structures

Percutaneous transluminal angioplasty was attempted in 20 patients with stenoses of venous structures. It concerned one stenosis in a native subclavian vein, 12 stenoses in venous bypass grafts and 7 stenoses in hemodialysis-access fistulas. Primary results were excellent for the procedures in the native vein and the venous bypass grafts with success in all patients (13/13). In the arteriovenous fistulas for hemodialysis, dilatation of the venous stenoses was only possible in 5 out of 7 patients. The subclavian vein stenosis did not recur within a follow-up period of 3 years. Of the stenoses in the venous bypass grafts, two lesions reoccluded within one week and 6 lesions recurred within one year. Two of these lesions were successfully redilated so that 6 lesions remain patent with a follow-up of more than one year. Of the 5 successful dilatations in hemodialysis-access fistulas, two lesions recurred within 2 months. Only 3 veins are still accessible for hemodialysis. It is concluded that attempts at balloon dilatation of stenoses in venous bypass grafts or hemodialysis-access fistulas are meaningful in order to prolong the life of these surgical procedures. Recurrence of stenoses is however likely to occur within one or two years.     

Directional atherectomy treatment for hemodialysis access: early results.

The Simpson atherectomy device was used to treat 12 intragraft stenoses, six complete subclavian vein occlusions, and 14 venous outflow stenoses in 24 patients undergoing hemodialysis. Patients were followed up clinically and by means of venography at approximately 1, 3, 6, 9, and 12 months after treatment. Twenty-eight atherectomy specimens were examined histologically. Twenty-six (81%) of 32 lesions were treated with initial technical success. Including technical failures, seven (58%) of 12 intragraft stenoses are angiographically patent at a mean of 5.0 months and five (50%) of 10 are clinically patent at 6 months. Three (50%) of six subclavian veins are angiographically patent at a mean of 5.6 months, and four (67%) of six are clinically patent at 6 months. Three (21%) of 14 venous outflow stenoses are angiographically patent at a mean of 5.0 months and five (38%) of 13 are clinically patent at 6 months. Histologic examination showed neointimal fibromuscular hyperplasia in 26 of 28 lesions. When 30% or less angiographic residual stenosis is used as the criterion for initial technical success, directional atherectomy appears to be effective therapy for intragraft stenoses and, with balloon angioplasty, for some catheter insertion-related subclavian occlusions. Directional atherectomy appears to have a recurrence rate for venous outflow stenoses similar to that for balloon angioplasty when the same criterion is used.     

Venous stenoses in dialysis shunts: treatment with self-expanding metallic stents

A flexible, self-expanding metallic endoprosthesis was employed for the treatment of venous outflow stenoses in four patients with a polytetrafluoroethylene shunt and two patients with a Brescia-Cimino shunt. The stenoses had led to shunt occlusion in five patients and to flow impairment in one. In the occluded shunts, thrombectomy and subsequent balloon angioplasty were performed in four patients, and percutaneous recanalization with angioplasty was performed in one. One shunt with decreasing flow was percutaneously dilated. Since the underlying stenoses recurred in four patients after 24 hours and did not respond sufficiently to angioplasty in two patients, up to four stents were placed in the venous segments. Thrombosis of the stents occurred in two patients after 24 hours and in one after 6 weeks and was successfully recanalized with thrombectomy in two. At 2-6 months follow-up, the stents and the shunts were patent in five patients. In three of these patients, intima hyperplasia, associated with narrowing of the stent lumen in two, was noted within 4 months after stent placement.     

Stenoses in dialysis fistulas: treatment with percutaneous angioplasty

Percutaneous transluminal angioplasty (PTA) was performed on 30 stenotic lesions in 25 dialysis access fistulas. The fistulas were in 23 patients with a mean age of 53 years. Lesions were detected with angiography within a few days after poor flow or increased venous pressure was documented during dialysis. Twenty-two lesions were in patients with polytetrafluoroethylene graft fistulas, five were in patients with bovine carotid fistulas, and three were in patients with endogenous arteriovenous fistulas. There were 28 venous stenoses (20 at the anastomotic site and eight more proximally) and two arterial stenoses. The overall success rate was 80%, with a 6-month patency of 76% and a mean patency after PTA of 9.4 months. Among the venous lesions, the success was 100% for proximal lesions and 71% for anastomotic lesions. There were two technical failures, which required surgery for revision of the fistulas, and four self-limited hematomas. PTA is a safe and effective treatment for stenoses in dialysis fistulas, particularly for lesions remote from the anastomotic sites.     

Percutaneous transluminal angioplasty (PTA) and venous stenting in hemodialysis patients with vascular access-related venous stenosis or occlusion

Aim of the studyTo present our experience with PTA and venous stenting in hemodialysis patients with vascular access (VA) related venous stenosis or occlusion.Patients – methodsWe studied retrospectively 22 hemodialysis patients with VA-related venous stenosis or occlusions that were treated with PTA and subsequent stenting. The following lesions were detected by digital subtraction venography: occlusion of the brachiocephalic and/or subclavian veins in four patients, stenosis (80–90%) of the same veins in 10 patients, stenosis (80–95%) of the axillary vein in four patients, brachial vein stenosis in two patients, and cephalic vein stenosis in two patients. The follow-up period ranged from 3 to 29 months (mean 15.4 ± 9.8 months). Primary and cumulative stent patency was recorded.ResultsTwenty-two primary venous PTA–stent implantation procedures were performed using 25 stents. The initial deployment of these 25 stents was technically successful, with complete opening (>80%) of the vein's lumen in all but one patient (95.4%). The patency of the vein immediately after the stenting procedure was greater than 90% in 13 patients, 80–90% in eight patients, and less than 40% in the case involving failure. Seventeen episodes of re-obstruction occurred in 13 patients (59%), and all were treated with the same PTA–stent procedures. At the end of the study period 47 stents had been placed in patients. The 3, 6, 12 and 24-month primary patency rates were 88.3%, 65.3%, 45.6% and 25.5%, respectively. Overall cumulative stent patency was 95.4% after 3 months, 79% after 6 months, 74% after 12 months, and 62.8% after 24 months.ConclusionPTA with primary venous stenting is an effective method for the treatment of VA-related stenosis or occlusion. However, repeat and sometimes multiple interventions are usually needed for the treatment of re-stenosis or re-occlusion episodes.     

血管成形术和内支架置入术对放射治疗后动脉损伤的治疗

目的评价经皮穿刺血管成形术和内支架置入术在放射治疗（简称放疗）后所致动脉疾病的治疗,及靶血管和内支架的长期支撑开放作用。方法１４例患者,因为放疗所致１８处动脉性病变,而给予血管球囊成形术治疗。并将１３个内支架置入于８例患者,分别治疗血管闭塞３例,动脉瘤１例,残存狭窄２例,多发狭窄１例,球囊成形术后再发狭窄１例。所有病例均用ＣＴ扫描和（或）多普勒超声检查,观察内支架及其靶血管内的血流情况。结果血管成形术成功治疗１４例,其中８例患者在动脉病变处置入内支架。随访８个月至５年,１１例动脉病变基本消失,血管造影示狭窄＜２０％,临床症状完全解除,３例狭窄＜３０％,临床症状改善。结论单一的血管成形术以及多技术综合运用,可有效治疗放疗所致的动脉性病变,应考虑其为动脉损伤性病变的首选治疗方法     

Use of the peripheral cutting balloon to treat hemodialysis-related stenoses

PURPOSE: To compare the effectiveness and safety of use of the peripheral cutting balloon (PCB) versus standard percutaneous transluminal angioplasty (PTA) for the treatment of hemodialysis-related stenoses. MATERIALS AND METHODS: This prospective, randomized multicenter clinical trial included 340 patients with stenotic or thrombosed hemodialysis grafts who were randomized to receive treatment with the PCB or PTA for venous outflow stenosis. One hundred seventy-three patients underwent treatment with the PCB, 101 with stenotic grafts and 72 with thrombosed grafts. PTA was used to treat 167 patients, 94 patients with stenotic grafts and 73 with thrombosed grafts. The follow-up period extended for 6 months. RESULTS: The procedural success rates were 80.8% and 75.4% for the PCB and PTA groups, respectively (P = .24). With use of the PCB, the primary patency rates of the target lesions were 84.3%, 65.8%, and 47.9% at 1 month, 3 months, and 6 months, respectively. With PTA, the primary patency rates of the target lesions were 77.7%, 63.4%, and 40.5% at 1 month, 3 months, and 6 months, respectively. The primary patency rates of the entire vascular access circuit were 82.6%, 61.0%, and 43.3% at 1 month, 3 months, and 6 months, respectively, with use of the PCB. For patients who were treated with PTA, the primary patency rates of the vascular access circuit were 75.9%, 61.0%, and 36.3% at 1 month, 3 months, and 6 months, respectively. When comparing the PCB and PTA, there was no difference in the 6-month primary patency rates in the target lesion (P = .373) or the entire vascular access circuit (P = .531). There were nine device-related complications in the PCB group (5.2%): five venous ruptures (2.9%), three venous dissections (1.7%), and one case of thrombosis (0.6%). There were no device-related complications in the PTA group. CONCLUSION: This prospective, randomized trial comparing use of the PCB versus standard PTA for treatment of hemodialysis-related venous stenoses demonstrated that the PCB provides equivalent 6-month patency to PTA for stenotic and thrombosed grafts.     

SMART stent for salvage of hemodialysis access grafts

PURPOSE: To evaluate the SMART stent for treating angioplasty-resistant hemodialysis access venous stenoses. MATERIALS AND METHODS: A retrospective study of 64 patients with polytetrafluoroethylene grafts who were treated with the SMART stent at 69 locations in the venous outflow tract was undertaken. Stents were used for elastic recoil after percutaneous transluminal angioplasty, venous rupture, or recurrent stenosis less than 3 months after angioplasty. When angiographic follow-up was available, the degree of in-stent restenosis was measured. Primary patency was determined, and, when applicable, compared with that of previous angioplasty treatments of the same lesion. RESULTS: The SMART stent was placed in 15 central veins and 54 peripheral veins, with a 98% technical success rate and a 97% clinical success rate. The mean primary access patency times were 14.9 months and 8.9 months in patients who received central and peripheral stents, respectively. In 19 patients whose central or peripheral venous stenoses were previously treated with angioplasty, the mean primary access patency was increased from 2.5 months to 10.6 months after placement of the SMART stent (P = .0003). Angiography in 29 patients after an average of 348 days showed 55% mean in-stent stenosis. The only stent-related complication occurred in a patient who had venous dissection associated with the edge of a SMART stent placed at the elbow. CONCLUSION: The SMART stent is safe and effective for treating dialysis access venous stenoses that are resistant to standard angioplasty.     

Percutaneous treatment of portal venous stenosis in children and adolescents with segmental hepatic transplants: long-term results

PURPOSE: To evaluate the long-term effectiveness of the percutaneous treatment of portal venous stenoses in children and adolescents with reduced-size hepatic transplants. MATERIALS AND METHODS: During the past 5 years, percutaneous transhepatic balloon venoplasty was attempted in 25 children and adolescents with anastomotic portal venous stenoses that occurred after reduced-size hepatic transplantation. All procedures were performed with direct puncture of the intrahepatic portal vein and with subsequent balloon dilation. Intravascular stents were deployed in patients with suboptimal results after dilation or with recurrent stenoses. RESULTS: Percutaneous venoplasty was technically successful in 19 of 25 patients. In the remaining six patients, portal venous occlusion precluded access to the extrahepatic portal vein. Intravascular stents were deployed in 12 patients for "elastic" (n = 5) or recurrent (n = 7) stenoses. Seven patients who underwent successful venoplasty without stent placement have required no further intervention. All stents have remained patent without further intervention. Portal venous patency has been maintained for 5-61 months (mean time, 46 months) in all 19 patients. CONCLUSION: Percutaneous treatment of portal venous stenoses is effective and long lasting in children with reduced-size hepatic transplants. In patients with elastic or recurrent lesions, portal venous stents have excellent long-term primary patency despite continued patient growth. Successful, percutaneous transhepatic venoplasty eliminates the need for surgical revision, portacaval shunting, or repeat transplantation.     

Peripheral venous stenoses of hemodialysis shunts: improved long-term patency rates with stent placement

PURPOSE: The purpose of this study was to evaluate the effectiveness of endovascular stents placed in the peripheral veins of hemodialysis shunts. MATERIALS AND METHODS: 156 endovascular stents were placed in the peripheral veins of 155 hemodialysis shunts with 220 stenoses. Among these, 106 stenoses of 93 hemodialysis shunts had been treated by percutaneous transluminal angioplasty (PTA) before stent placement. RESULTS: The initial success rate was 97.7%. Primary radiologic patency rates of the stents at 6 months, 1 year, and 2 years were 69.8%, 49.1%, and 45.8%, respectively. Secondary radiologic patency rates at 1 year, 2 years, and 3 years were 94.0%, 91.8%, and 88.0%, respectively. Primary clinical patency rates at 6 months, 1 year, and 2 years were 64.4%, 43.4%, and 27.3%; while secondary clinical patency rates at 1 year, 2 years, and 3 years were 93.5%, 86.5%, and 73.4%, respectively. Radiologic and clinical primary patency rates of 106 stenoses and 93 hemodialysis shunts were significantly higher than those of PTA that had been performed before stents were placed. CONCLUSION: Stent placement for stenoses of the peripheral veins of hemodialysis shunts recurring in three months and treated by PTA alone can improve long-term patency.     

Percutaneous transluminal angioplasty of stenotic lesions in dialysis vascular accesses

Forty-five stenoses behind arteriovenous fistulas in 35' haemodialysed patients were treated with percutaneous transluminal angioplasty (PTA). Immediate stenoses dilatation results in relation to the AVF type were haemodynamically significant in 40 cases (88%), with poorer results on bovine heterograft stenoses. Dilatation results in relation to the site of the lesion showed haemodynamically efficient angioplasty on stenoses next to the anastomosis (67.5%) but a poor result on distal lesions (4 cases). We observed 4 cases of thrombosis but 2 recovered after treatment, one after local fibrinolytic perfusion one after surgical thrombectomy. Follow-up over a period of one to 18 months (mean 8 months) including angiography and appreciation of the dialysis quality were performed in 30 patients who had a successful dilatation. PTA appears to be a technically feasible and clinically effective method of treating stenoses lying on the venous limb fistula in patients on chronic haemodialysis.     

A comparison study of self-expandable stents vs balloon angioplasty alone in femoropopliteal artery occlusions

In a group of 26 patients percutaneous transluminal (balloon) angioplasty (PTA) and stents (Wallstents) were applied and in another 26 matched patients PTA alone was used as primary treatment for femoropopliteal occlusions of 3 cm or longer. Five patients with stents showed early thrombosis necessitating catheter thrombolysis and/or thrombus aspiration. Ten patients had recurrent stenoses within 12 months, mostly due to neointimal hyperplasia. Following three late catheter reinterventions, a cumulative secondary patency rate of 69% was achieved after 12 months. The group of patients treated by PTA alone showed a 12 months patency rate of 65% without reinterventions. In 8 other patients, stents were inserted for recurrent obstructive or PTA-resistant lesions, and similar results as with the stents above were obtained. Thus, these stents do not improve primary results of PTA in femoropopliteal occlusions but may be useful secondarily after unsuccessful PTA.     

Drug-eluting stent insertion in the treatment of in-stent renal artery restenosis in three renal transplant recipients

Percutaneous transluminal angioplasty (PTA) with or without stent insertion is the treatment of choice in transplant renal artery stenosis. However, in-stent restenosis occurs in as many as 13% of patients after PTA and stent insertion. This article describes three patients with recurrent transplant renal artery in-stent stenosis who were treated with paclitaxel-eluting stents. In two patients, the transplant renal artery remained patent after insertion of the drug-eluting stent (DES), and one patient required balloon angioplasty 7 months after the DES was inserted.     

Endovascular stent placement for angioplasty-induced venous rupture related to the treatment of hemodialysis grafts.

PURPOSE: To assess the use of endovascular stents for treating rupture after percutaneous transluminal angioplasty (PTA) in the maintenance of hemodialysis grafts. MATERIALS AND METHODS: From February 1, 1994, to August 1, 1997, 683 hemodialysis-related angioplasty procedures were performed on 277 patients to treat thrombosed or poorly functioning polytetrafluoroethylene (PTFE) hemodialysis bridge grafts. In each of these procedures, angioplasty of the venous anastomosis or the outflow vein was performed. This study is a retrospective review to analyze uncovered endovascular stents placed to treat ruptures after PTA. RESULTS: Fourteen ruptures were treated with use of an uncovered metal stent. Stent placement was technically successful in 11 of 14 patients, with clinical success in 11 of 14 cases. The primary patencies at 30, 60, 90, and 120 days were calculated by means of Kaplan-Meier life-table analysis; these were 63%, 54%, 46%, and 46%, respectively. The secondary patencies at 60, 120, and 180 days were 85%, 75%, and 75%, respectively. No complications were attributable to stent placement. The results are comparable to those of stents placed for reasons other than rupture, and support the efficacy of their use for this indication. CONCLUSION: Endovascular stent placement is a safe and effective means of salvaging angioplasty-induced rupture that occurs during the treatment of hemodialysis grafts.     

External beam irradiation as an adjunctive treatment in failing dialysis shunts

PURPOSE: To evaluate the utility of low-dose irradiation as adjunctive treatment for failing dialysis shunts related to stenoses. MATERIALS AND METHODS: Thirty-one patients with 41 lesions in their dialysis shunts were successfully enrolled for this study. After imaging of the shunt and calculation of venous stenoses, each patient was randomized into one of two segments of the protocol: (i) angioplasty and/or stent placement alone, and (ii) angioplasty and/or stent placement followed by external beam irradiation. All patients with significant venous stenoses (> or =50%) were treated with appropriately sized PTA (percutaneous transluminal angioplasty) and Wallstents. Patients randomized to the external irradiation segment underwent localized irradiation via a Theratron cobalt unit of 7 Gy 0-24 hours and 24-48 hours after intervention. Those patients randomized to the control group received no additional treatment. Clinical follow-up included resumption of successful dialysis with appropriate hemodynamic parameters. Two follow-up shunt images were obtained, follow-up 1 (fu-1) from 90 to 179 days and follow-up 2 (fu-2) from 180 to 365 days. Percentages of significant recurrent stenoses, defined as greater than 50%, were recorded and re-treated as needed. RESULTS: Sixteen of the 31 patients underwent external beam irradiation. There were 21 lesions in the test group that underwent irradiation after intervention, and 20 lesions were treated with intervention alone. There were seven native arteriovenous fistulas and 24 Gore-tex grafts. All stenoses were either venous outflow stenoses (68%) or central stenoses (32%). The authors utilized chi2 analysis to compare restenoses rates between the control and irradiated groups at fu-1 (P<.99) and fu-2 (P<.10). CONCLUSIONS: Although the results show that external beam irradiation has minimal effects on the restenoses of dialysis grafts when used in conjunction with PTA and stent placement, further studies with a larger, more homogenous population are needed to assess the trend of improving patency rates after external beam irradiation.     

Arterial stent placement with use of the Wallstent: midterm results of clinical experience

Self-expandable stents of the Wallstent type were used in 26 iliac and 15 femoropopliteal artery lesions of 31 patients to treat stenoses or occlusions. The indications were confined to complex lesions, including residual stenoses and dissections after percutaneous procedures or previous surgery in the iliac artery lesions, and long-segment (mean, 13.5 cm) occlusions with inadequate response to percutaneous recanalization in the femoropopliteal artery lesions. In the iliac artery group, after stent placement, 96% of the lesions were patent at a mean follow-up of 16 months (range, 6-30 months). In the femoropopliteal artery group, of 11 patients available for follow-up, only six had patent stents at 7-26 months (mean, 20 months). Four of these six patients required one to three secondary interventions. Self-expanding endoprostheses are of great value in complex iliac artery lesions where simple balloon dilation is insufficient. Stent placement for long femoral artery lesions should be performed with utmost reserve, and the extent of stent placement should be as short as possible.     

Metallic stents deployed in synthetic arteriovenous hemodialysis grafts

OBJECTIVE: The purpose of our study was to review the success of metallic stent treatment of intragraft stenoses in patients with synthetic arteriovenous hemodialysis grafts. MATERIALS AND METHODS: Between May 1993 and May 1997, 19 metallic stents were placed in 11 patients (seven women, four men; age range, 41-83 years) to treat elastic intragraft stenoses or graft dissections. Before stent placement, all patients had experienced multiple episodes of graft thrombosis, had very limited vascular access for hemodialysis, and were considered poor surgical candidates. RESULTS: The technical success rate was 100%, and there were no procedural complications. Using life-table analysis, we found primary patency to be 36% at 6 months after stent placement, 12% at 12 months, and 12% at 18 months. Secondary patency was 91% at 6 months after stent placement, 71% at 12 months, and 47% at 18 months. The mean and median patencies per intervention were 4.2 and 3.6 months, respectively. Mean and median secondary graft patencies were both 14 months (range, 3 days-32 months). Puncture through the stents occurred during dialysis, causing stent distortion and fracture. Eight stents had a linear fracture suggesting compression contributed to the stent distortion. No clinically evident complications related to stent placement occurred. CONCLUSION: Metallic stent deployment can salvage access in synthetic arteriovenous grafts by alleviating intragraft stenoses. Patency of intragraft stents is similar to venous stents used to treat other hemodialysis-related stenoses; however, fracture of Wall-stents occurs with prolonged graft use, especially in areas of needle punctures.