Transluminal stent graft repair with Wallgraft endoprosthesis in a porcine arteriovenous graft pseudoaneurysm model

PURPOSE: Pseudoaneurysm is a known complication of arteriovenous grafts in chronic hemodialysis and can result in graft disruption or thrombosis if left untreated. This study evaluated the safety and efficacy of endovascular repair with Wallgraft endoprosthesis (Boston Scientific, Inc, Watertown, Mass) in a porcine arteriovenous graft (AVG) pseudoaneurysm model. Materials and Methods: Bilateral groin AVG pseudoaneurysms (n = 18) were created with an oversized Dacron interposition graft within a polytetrafluoroethylene femoral AVG in nine domestic swine and allowed to mature 28 +/- 4 days (standard deviation). Transluminal placement of Wallgraft was performed to exclude the pseudoaneurysm from the AVG circulation. Hemodialysis was performed (400 mL/min x 1 hour, with intravenous heparin 30 units/kg) every 4 days for a total of 6 weeks via 15-gauge needles in the treated AVG pseudoaneurysm site. Arteriography and duplex ultrasound scan were performed to determine AVG patency and pseudoaneurysm flow. Histologic evaluation was performed to determine Wallgraft morphology. In vitro pulsatile flow chamber was used to determine maximal flow volume without peri-Wallgraft endoleak. RESULTS: All AVG pseudoaneurysms were successfully excluded with the Wallgrafts. Twelve AVG (67%) remained patent at the completion of the study. No Wallgraft migration occurred from hemodialysis. Transient peri-Wallgraft endoleak (<2 hours after hemodialysis) was present in 13 of 18 (72%) and four of 12 (33%) AVG pseudoaneurysms by weeks 1 and 6, respectively. With maintenance of an intraluminal pressure of 80, 100, 120, 140, and 160 mm Hg in the pulsatile flow chamber, the maximal flow rates without peri-Wallgraft endoleak were 625 +/- 120, 650 +/- 145, 620 +/- 95, 425 +/- 110, and 262 +/- 86 mL/min. Scanning electron microscopy showed a neointimal layer covered with thrombus on the Wallgraft surface. CONCLUSION: Endoluminal placement of Wallgraft endoprosthesis provides adequate structural support for continuous hemodialysis after AVG pseudoaneurysm exclusion. Transient blood flow in the pseudoaneurysm cavity may occur immediately after the hemodialysis, which may represent the effect of heparin used during hemodialysis. This study suggests Wallgraft is a safe and effective treatment for AVG pseudoaneurysm and permits continuous hemodialysis.     

A proposed management algorithm for fistulae between hemodialysis access circuits and adjacent veins

Purpose: Fistulae between an arteriovenous hemodialysis graft (AVG) or fistula (AVF) and an adjacent vein are an unusual complication of hemodialysis access. Such fistulae may theoretically cause steal syndrome, extremity edema, or access dysfunction. We sought to use our experience and existing literature to develop a management algorithm for this access complication. Methods: Twelve patients with AVG/AVF to adjacent vein fistulae found on fistulography were identified using a quality assurance database. Indications for fistulography, treatment rendered for both the fistulae and access stenosis, and outcome of treatment were determined. AVG/AVF to adjacent vein fistulae, when identified and considered to be significant, were treated with embolization. Results: Five out of twelve patients had successful embolization of their AVG/AVF to adjacent vein fistulae. Reasons for treatment included partial thrombosis of the access to the level of the fistula (n=1), contribution to bleeding during dialysis (n=1), and concern for competing flow causing thrombosis (n=5). No recurrence was identified. Seven patients did not undergo embolization either because of failure to recognize the fistula (n=3) or determination that treatment was not indicated (n=4). Two untreated fistulae were found occluded at follow-up. Additional access treatment included angioplasty (n=11), covered stent (n=1), and mechanical thrombectomy (n=3). Conclusions: The significance of AVG/AVF to adjacent vein fistulae remains unclear; some resolve spontaneously, possibly related to PTA of outflow stenosis. Embolotherapy is an effective treatment for such fistulae when determined to be significant.     

Creation of secondary arteriovenous fistulas: maximizing fistulas in prevalent hemodialysis patients

National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) guideline 29 suggests that a patient should be evaluated for a secondary arteriovenous fistula (AVF) following each episode of dialysis access failure. Regretfully, it does not appear that this approach is used, even though recent data have emphasized that veins suitable for the creation of a secondary AVF can be identified in dialysis patients who are receiving dialysis via a synthetic arteriovenous graft (AVG) or other type of potentially dysfunctional vascular access. In this study nine patients (five with an AVG and four with an AVF) with vascular access dysfunction undergoing percutaneous interventions were evaluated for secondary AVF creation. All were found to have suitable vascular anatomy and had the AVF created. The secondary fistula was successful in all nine patients with a mean follow-up of 4.8 +/- 1.4 months in post-AVG cases and 5.6 +/- 1.7 months in the post-AVF patients. In addition, it was possible to continue uninterrupted dialysis without the use of a tunneled dialysis catheter in three of the patients with AVGs. This experience demonstrates the validity and success of this approach to the management of dialysis access dysfunction. In the ongoing effort to optimize vascular health status, we suggest that during percutaneous interventions, patients should routinely have identification of vessels suitable for creation of a secondary AVF.     

Improvements in dialysis access survival with increasing use of arteriovenous fistulas in a Veterans Administration medical center

BACKGROUND: Native arteriovenous fistulas (AVFs) have been found to exhibit higher survival rates and lower complication rates than prosthetic grafts (AVGs). METHODS: Between August 2001 and December 2003, 93 patients with end stage renal disease (ESRD) had primary dialysis access placed at a single Veterans Administration medical center. Of these 93 patients, 67 had AVFs created and 26 patients had AVGs implanted. RESULTS: The percentage of patients who did not require additional intervention was 84% (56 of 67) for AVF and 78% (21 of 26) for AVG after 4 to 31 months of follow-up evaluation. In the AVF group, repeat interventions were as follows: collateral ligation (4), angioplasty owing to central stenosis (2), AVF ligation due to arterial steal phenomenon (1), and new AVF creation owing to clotting (1). Four AVFs were later converted to AVG. In the AVG group there were 4 venous anastomosis stenosis seen in 3 patients who required angioplasty. Two patients needed thrombectomy and revision, and 1 graft was removed because of infection. AVF prevalence in our dialysis patients was 63%, with 33% AVG and 4% temporary catheter. CONCLUSIONS: The National Kidney Foundation-Dialysis Outcome Quality Initiative (NKF-DOQI) guidelines for dialysis access reawakened interest in maximizing the use of renal veins for AVF. AVFs created by using the patient's native vein provides the best vascular access for dialysis when compared with prosthetic grafts. AVF has better long-term patency with fewer complications.     

Endovascular Stent-Graft Treatment of Traumatic Arterial Lesions

Twenty-nine cases of post-traumatic false aneurysms and arteriovenous fistulas (AVF), with a mean follow-up of 24 months (1-65 months), are presented here. Diagnosis was established by color duplex and arteriogram. The time between injury and treatment varied between 3 days and 61 months. Endovascular treatment was accomplished using a covered Palmaz stent [vein, polytetrafluoroethylene (PTFE), or polyester], Corvita endoluminal graft, or a Wallgraft. Complimentary treatment of a branch injury was performed using a detachable balloon in one patient. The initial result was favorable for all patients. One case of asymptomatic stenosis of an iliac stent graft and three occlusions of the stent (one subclavian, one axillary, and one internal carotid) were registered during the follow-up period, and no clinical manifestations of the occlusions were reported. Endovascular treatment of post-traumatic false aneurysms and AVF appears to be a promising alternative for treatment of these lesions. Less pain and disability as well as rapid recovery time and lower cost after endovascular treatment compare favorably to the standard surgical technique.     

血液透析动-静脉造瘘术后并发症的处理

目的 总结血液透析（血透）患者动静脉造瘘手术后并发症的处理经验。方法 收集我院120例患者,造瘘手术144例次,其中行内瘘134例次,人工血管瘘10例次。结果 术后扩要并发症：（1）血栓形成,AVF：17%、AVG：60%。内瘘血栓形成多发生于6周以内,治疗以重建新瘘道为主,或改建人工血管瘘;人工血管瘘血栓以取栓治疗为主,同时尽可能修复静脉流出道。（2）感染,AVG感染率为10%,行引流行移植物切除手术。（3）充血性心功能衰竭：3.5%,超滤、强心治疗。（4）窃血：1.4%,行血管成型和旁路架桥手术治疗。结论 积极预防和正确处理造瘘术后并发症可延长瘘道的通畅时间。     

介入导管技术在动静脉内瘘失功治疗中的应用

目的:探讨动静脉内瘘(AVF)失功后介入手术的治疗方法,评估其治疗效果及应用价值。方法:回顾性分析自2006年4月—2015年1月行介入手术治疗的20例自体AVF失功患者的临床资料。结果:20例患者中,16例经静脉端造影,4例经股动脉-主动脉-腋动脉路径造影;单纯吻合口狭窄4例,行球囊扩张后狭窄明显改善;吻合口狭窄伴血栓形成有5例,切开取栓后再行球囊扩张治疗;静脉端血栓形成3例,切开取栓后返血良好;静脉端狭窄合并血栓形成7例,行切开取栓后再行球囊扩张治疗;头静脉长段闭塞1例,改用人工血管行AVF术。术后全部患者经该血管通路恢复透析治疗,透析时流量均200 m L/min。共17例患者获得随访,平均随访时间13.2个月,12个月通畅率为47.1%。结论:介入导管技术在治疗AVF失功方面是安全、有效的。     

Outcomes of Elderly Patients after Predialysis Vascular Access Creation

Uniform vascular access guidelines for elderly patients may be inappropriate because of the competing risk of death, high rate of arteriovenous fistula (AVF) maturation failure, and poor vascular access outcomes in this population. However, the outcomes in elderly patients with advanced CKD who receive permanent vascular access before dialysis initiation are unclear. We identified a large nationally representative cohort of 3418 elderly patients (aged ≥70 years) with CKD undergoing predialysis AVF or arteriovenous graft (AVG) creation from 2004 to 2009, and assessed the frequencies of dialysis initiation, death before dialysis initiation, and dialysis-free survival for 2 years after vascular access creation. In all, 67% of patients with predialysis AVF and 71% of patients with predialysis AVG creation initiated dialysis within 2 years of access placement, but the overall risk of dialysis initiation was modified by patient age and race. Only one half of patients initiated dialysis with a functioning AVF or AVG; 46.8% of AVFs were created <90 days before dialysis initiation. Catheter dependence at dialysis initiation was more common in patients receiving predialysis AVF than in patients receiving AVG (46.0% versus 28.5%; P<0.001). In conclusion, most elderly patients with advanced CKD who received predialysis vascular access creation initiated dialysis within 2 years. As a consequence of late predialysis placement or maturation failure, almost one half of patients receiving AVFs initiated dialysis with a catheter. Insertion of an AVG closer to dialysis initiation may serve as a “catheter-sparing” approach and allow delay of permanent access placement in selected elderly patients with CKD.     

Epidemiology of vascular access and complications in patients undergoing maintenance hemodialysis in Tianjin

Objective To investigate the use of vascular access and complication incidence in patients undergoing maintenance hemodialysis in Tianjin. Methods Patients undergoing maintenance hemodialysis in the third level of first-class hospital in Tianjin were investigated. The investigate method was live interview. Two thousand six hundred and fifty-one cases were available. Basic data, age of dialysis, type of vascular access, age of vascular access and complications were recorded. The differences in clinic data and complications between patients using arteriovenous fistulas (AVF) and central venous catheter (CVC) as vascular access were compared. Results There were 2047 (77.22%) patients using AVF as vascular access, 559 (22.59%) patients using tunnel type central venous catheter, and 5 (0.19%) patients using arteriovenous graft (AVG) for maintenance hemodialysis. Most patients used temporary catheter as the first vascular access [2484(93.70%)]. Compared to AVF, CVC had high incidence of thrombosis and infection in the first four years (P=0.003). Conclusions AVF remains the first choice for maintenance hemodialysis. Most patients use AVF as their vascular access. The second preferred choice is CVC. The management of late chronic kidney disease should be enhanced to avoid the high usage of temporary catheter.     

Looking Beyond “Fistula First” in the Elderly on Hemodialysis

Vascular access preparation, a pervasive challenge in hemodialysis (HD), is emerging as a multidimensional subject in geriatric nephrology. Previously published guidelines declared arteriovenous fistulas (AVF) as the preferred vascular access for all patients on HD. In this article, the benefit–risk evidence for using AVF versus an alternative access (arteriovenous graft [AVG] or tunneled central venous catheter [TCVC]) in the elderly is pondered. Compared to their younger counterparts, the elderly have significantly lower survival rates independent of the vascular access used for HD. Recent studies point to comparable dialysis survival rates between AVF and AVG or TCVC in subgroups of elderly patients, as well as lower rates of access‐related infections, and lower catheter dependence after AVG compared to AVF construction in these patients. Comprehensive and longitudinal assessments that integrate comorbidities, physical function, cognitive status, and quality of life to estimate prognosis and assist with vascular access selection ought to be employed. In circumstances where patient survival is limited by comorbidities and functional status, AVF is unlikely to confer meaningful benefits compared to AVG or even TCVC in the ill elderly.     

Cutting balloon angioplasty in hemodialysis arteriovenous fistula stenosis resistant to conventional balloon angioplasty

Objective To investigate the efficacy and safety of cutting balloon angioplasty for the treatment of hemodialysis arteriovenous fistula stenosis resistant to conventional percutaneous transluminal angioplasty (PTA). Methods The patients with arteriovenous fistula stenosis who had suboptimal results (residual stenosis ＞30%) by conventional PTA from December 2011 to February 2015 were enrolled. All the patients received cutting balloon angioplasty were rechecked every three months. Results A total of 25 patients with age of (60.7±12.9) years had suboptimal PTA results. Eleven patients with native arteriovenous fistula (AVF) and 14 patients with graft fistula (AVG) underwent cutting PTA for 30 times. The technical success rate was 86.7% and clinical success rate was 100%. The diameter stenosis pre-procedural and post-procedural of cutting PTA was (1.7±0.6) mm and (4.5±0.8) mm respectively (P＜0.05). Six patients had multiple lesions and the stenosis consisted of 21 outflow venous, 6 graft-to-vein anastomosis, 6 cephalic arch, 2 artery and 1 puncture hole stenosis. The primary access patency at 3 and 6 months for AVF group were 70.0% and 10.0%, while for AVG group the figures were 64.3% and 7.1% (P＞0.05). The secondary access patency at 3 and 6 months for AVF group were 70.0% and 30.0%, while for AVG group the figures were 85.7% and 64.3% (P＞0.05). The follow-up time was (8.1±7.3) months. The restenosis rate was 64.0%. Cutting PTA failed to achieve technical success for four times, of whom 2 patients required graft stent implantation and 2 patients required ultra-high-pressure balloons angioplasty to finally achieve technical success. The median survival time of fistula was 173 days. Conclusions Cutting balloon angioplasty have well short-term patency and safety in arteriovenous fistula stenosis resistant to conventional PTA, especially for calcified lesion or "balloon waist". Although it could provide a satisfied long patency by recurrent PTA, the use of cutting balloon would be not advocated as the first-line treatment for fistula stenosis. The efficacy superiority of cutting balloon between AVF and AVG, as well as the cost-effect comparison between cutting balloon and high-pressure balloon, remains unclear, the verification of which requires large-sampled, prospective and randomized studies.     

Repair of a combined femoral pseudoaneurysm and arteriovenous fistula using a covered stent graft

Our purpose was to demonstrate clinical efficacy of covered stent use in the peripheral vasculature. A 68-year-old man was transferred from an outlying hospital for evaluation and treatment of a pulsatile mass in his right groin after cardiac catheterization. Imaging with duplex ultrasound and diagnostic arteriogram demonstrated a 6-cm pseudoaneurysm (PSA) of the right superficial femoral artery (SFA) and an arteriovenous fistula (AVF) of the SFA and the profunda vein. Using a covered stent extending from the proximal SFA across the origins of the AVF and PSA, complete exclusion was attained. Follow-up ultrasound at 6 weeks revealed a patent stent, no AVF, and thrombosis of the PSA. Endovascular treatment of peripheral lesions (AVF/PSA) in an elective to semi-elective setting offers patients a safe, less invasive treatment option to consider over traditional open surgery. Consequently, a formidable reduction in incision length, wound infection, and postoperative immobility can be expected.     

Ultrasound evaluation and interventional therapy for peripheral vascular access stenosis in dialysis patients

Objective To investigate the patency rate and restenosis after percutaneous transluminal angioplasty (PTA) for the treatment of arteriovenous fistula (AVF) and arteriovenous graft (AVG) stenosis in dialysis patients. Methods The patients who were successfully treated by PTA for the first time in the blood purification center of the 2nd Affiliated Hospital of Nanjing Medical University from January 2016 to June 2017, including 71 cases of AVF in the forearm, 52 cases of AVF in the upper arm and 59 cases of AVG were recorded. The data of different stenosis parts were analyzed before and after treatment and followed up for 12 months. The initial patency rate and assisted-PTA patency rate were observed at 3 months, 6 months, 9 months, and 12 months after ultrasound interventional therapy, and the initial patency time for patients who needed to reintervention among all types of pathways were recorded. Results The initial patency rates at 3 months, 6 months, 9 months and 12 months after ultrasound interventional therapy were 98.59%, 90.14%, 71.93%, 54.93% respectively in forearm AVF, 90.38%, 65.38%, 42.31%, 32.69% respectively in upper arm AVF, 91.53%, 32.20%, 6.78%, 1.69% respectively in AVG, and the PTA-assisted patency rates were 98.59%, 97.18%, 95.77%, 94.37% respectively in forearm AVF, 92.31%, 86.54%, 84.62%, 80.77% respectively in upper arm AVF, 100.00%, 98.31%, 96.61%, 93.22% respectively in AVG, while the initial patency time was (8.99±3.54) months in forearm AVF, (6.33±3.01) months in upper arm AVF, (4.80±1.40) months in AVG respectively. Conclusions Ultrasound can comprehensively evaluate the function of peripheral vascular access, guide PTA treatment, and evaluate treatment outcomes. Ultrasound intervention therapy has best initial patency rate for forearm AVF stenosis. The prognosis of upper arm AVF stenosis PTA is relatively poor due to the easy cephalic stenosis. Although AVG has a short interval of restenosis, it can achieve a better long-term patency rate through regular intervention with ultrasound intervention.     

下肢人工血管移植物内瘘的应用及中远期效果观察

背景与目的：终末期肾病（ESRD）是各种原因导致的慢性肾脏疾病进展到终末期阶段,大部分ESRD患者选择血液透析肾脏替代治疗,而功能良好且通畅率令人满意的血管通路对其至关重要。上肢是患者构建血液透析通路的首选位置,但部分患者因各种原因存在上肢血管或中心静脉资源耗竭等问题,无法构建上肢血管通路。对此,可以考虑构建下肢人工血管移植物内瘘（AVG）作为患者长期血液透析的通路,本研究回顾性分析构建下肢AVG患者的临床资料与中远期随访结果,以期为此提供经验证据。 方法：回顾2014年3月—2018年11月南方医科大学南方医院血管外科32例构建下肢AVG的ESRD患者临床资料与随访资料,分析患者的相关临床指标,用Kaplan-Meier法计算患者术后的初级通畅率和次级通畅率。 结果：全组患者术后均能触及AVG震颤,围术期1例患者出现慢性心功能不全急性发作,予药物、加强透析治疗后未见明显好转后死亡;2例患者出现移植物血栓形成,切开导管取栓后造影未见吻合口及流出道静脉狭窄,术后AVG恢复通畅,顺利透析。所有患者围术期间无感染、透析通路相关性肢端缺血综合征（HAIDI）、假性动脉瘤等并发症发生。术后随访1~60个月,中位随访时间14.1个月。随访期间出现AVG狭窄13例（40.6%）,闭塞10例（31.3%）,经外科手术或腔内手术修复后恢复AVG通畅;人工血管移植物感染3例（9.4%）,其中1例患者移植物局段感染,行人工血管移植物感染段切除,自体静脉移植术后顺利保留AVG并用于透析,2例患者因移植物全段感染予全段切除。期间未出现假性动脉瘤、HAIDI等并发症。患者术后初级通畅时间为（20.4±3.32）个月,1、2、3年初级通畅率为64.6%、44.7%、19.6%;次级通畅时间为（38.7±5.52）个月,1、2、3年次级通畅率为79.6%、79.6%、54.6%。 结论：下肢AVG经修复后可达到较满意的次级通畅率,对于无法建立上肢血管通路患者而言,是安全、有效的通路选择。规范的术前评估、手术及穿刺中严格的无菌操作以及规律的随访是保证其远期通畅的重要因素。     

Feasibility of Trans‐Radial Approach in Percutaneous Intervention for Upper Arm Dialysis Access

Background: This retrospective study evaluated the feasibility and efficacy of trans‐radial intervention for upper arm dialysis access. Methods: This study retrospectively reviewed 165 trans‐radial interventions performed for upper arm dialysis access in 101 patients. Sixty‐nine patients had arteriovenous graft (AVG), and 32 had arteriovenous fistula (AVF). Balloon angioplasty was performed in 66 stenotic dialysis accesses and 99 thrombosed dialysis accesses. Thrombosed dialysis access was further managed by additional balloon thrombectomy with or without urokinase injection. Results: Procedural time was 46.7 ± 25.5 minutes. Anatomic and clinical success rates were 89.7% and 84.2%, respectively. The rate of complications, most of which involved lesion rupture with contrast‐media extravasation and distal embolism, was 9.7%. Pretreatment stenosis was more severe (p = 0.01) and the prevalence of total occlusion was higher (p < 0.01) in the AVG group than the AVF group. The success rate and complication rate did not statistically differ (p = 0.59). Additionally, the thrombosed group had a lower success rate (p = 0.02), a higher complication rate (p < 0.01) and a longer procedural time (p < 0.01) than the stenotic group. Conclusions: Comparison with previous studies employing the traditional approach reveals that trans‐radial intervention has a comparable success rate, procedural time and complication rate for upper arm dialysis access. Therefore, trans‐radial intervention is a safe and feasible technique for upper arm dialysis access.     

Predicting vascular access failure: A collective review

SUMMARY: The maintenance of vascular access for haemodialysis contributes a large burden of morbidity and cost to any dialysis unit. Identifying vascular access at risk of thrombosis is an evolving and important aspect to the management of any haemodialysis patient. Haemodynamic profiles of native fistulas and arteriovenous grafts differ significantly, and, as such, the sensitivity of the specific monitoring techniques to detect dysfunction varies depending on access type. Multiple strategies are now available for monitoring vascular access including measuring intra-access pressure and access blood flow, or screening for significant stenoses with Doppler ultrasonography. the ability of each strategy to detect significant stenosis is reviewed by looking at the evidence for both arteriovenous fistula (AVF) and arteriovenous grafts (AVG), separately. the majority of published literature involves AVG, and measuring access blood flow is the modality of choice. the best method for measuring flow is not known. For AVF, much less is known, and it is not clear whether monitoring will decrease the thrombosis risk and prolong access life. Recommendations for AVF cannot be made until more evidence becomes available.     

Effect of Secondary Interventions on Patency of Vascular Access Sites for Hemodialysis

PURPOSE: To determine the impact of secondary procedures performed to maintain arteriovenous fistula (AVF) and arteriovenous graft (AVG) patency. METHODS: There hundred and eighty six vascular access procedures were retrospectively evaluated. 156 (40.4%) patients required radiological interventions to treat acute thrombosis, swelling of the extremity with the access site, insufficient hemodialysis, or stenosis at an anastomotic site. RESULTS: The 386 cases comprised 106 AVGs and 280 AVFs. In 138 of the 156 cases, which required a radiological intervention, the treatment was successful and saved the vascular access site. The unassisted post-intervention patency time for these 138 successful cases was 13.1 +/- 12 months (range, 1-65 months). Twenty-nine (63%) of the 46 access sites treated with surgical thrombectomy were saved. CONCLUSIONS: Frequent, regular follow-up of hemodialysis patients with vascular access sites is the best way to diagnose problems early and allow the best chance of long-term function.     

When Should a Patient Receive an Arteriovenous Graft Rather Than a Fistula?

There has been a dramatic increase in the placement and use of arteriovenous fistulas (AVF) in US patients with chronic kidney disease over the past few years, in accordance with strong recommendations by Fistula First Initiative and KDOQI guidelines. However, AVF nonmaturation remains a substantial obstacle to achieving functional AVFs in a subset of patients, despite the widespread use of preoperative vascular mapping to assist surgeons in planning access surgery, and the growing use of interventions to salvage nonmaturing AVFs. In the right patient, aggressive efforts result in a functioning AVF, which provides adequate dialysis with relatively few interventions required to maintain its long‐term patency for dialysis. In the wrong patient, aggressive efforts to achieve a mature AVF may result in numerous failed surgical and percutaneous procedures and prolonged catheter dependence, with all its associated complications. Thus, strict recommendations to place an AVF in all dialysis patients might not benefit every patient, and may actually harm some patients. There are no randomized clinical trials to address which patients are more suitable for placement of an arteriovenous graft (AVG), rather than an AVF. However, there is a wealth of observational studies, which taken cumulatively, may assist clinicians in identifying those patients who should receive an AVG. In this article, we review the relevant published literature regarding this topic and provide suggestions for stratifying patients who should receive each type of vascular access.     

Vascular screening prior to placement of tunnelled and cuffed hemodialysis catheters

Purpose: To demonstrate the importance of venous vascular screening before the placement of tunneled and cuffed hemodialysis catheters in patients requiring hemodialysis prior to placement and/or maturation of an arteriovenous fistula (AVF) or graft (AVG). Methods: Between October 1998 and March 2000, all patients requiring hemodialysis access placement were prospectively evaluated with duplex ultrasound for status of upper extremity vessels and central veins prior to selection of a permanent access site. When interim tunneled and cuffed hemodialysis catheters were required, they were placed on the side contralateral to proposed AVF/AVG placement. No catheters were placed without initial vascular screening. The study group was compared to historical controls during a similar period (April 1997 through September 1998) when no vascular screening was performed. Results: During the study period, 234 screening duplex ultrasound examinations were performed in 244 patients. Ten patients required no screening prior to access site placement. Overall, 353 catheters were placed, 243 (69%) on the right side and 110 (31%) on the left side. During the control period, 394 catheters were placed in 255 patients, 306 (78%) right-sided and 88 (22%) left-sided. The increase in left-sided catheters with ultrasound screening and careful planning for future access sites was significant (p<0.01). Conclusion: Vascular-screening-directed catheter placement significantly alters the side of catheter placement when compared to a management protocol without prior screening. Such screening helps identify the side of permanent access placement, while directing interim catheters to the contralateral side such that central veins may be preserved for permanent access.     

球囊扩张联合覆膜支架植入治疗人造血管动静脉内瘘狭窄

目的 探讨球囊扩张联合覆膜支架植入治疗人造血管动静脉内瘘(AVG)狭窄的临床疗效.方法 前瞻性选取15例经皮腔内血管成型术(PTA)疗效欠佳的AVG狭窄患者,且具备以下特点:狭窄长度不超过7 cm,狭窄程度大于50％;PTA后3个月内狭窄复发2次或以上;扩张后残余狭窄＞30％或狭窄部位立即弹性回缩.所有患者在数字减影血管造影(DSA)下行球囊扩张后植入不同内径的聚四氟乙烯覆膜支架.结果 男3例,女12例,平均年龄(66±12)岁.支架植入前内瘘平均使用时间为(19.5±15.0)个月.共植入支架16枚,技术成功率100％,植入部位为静脉吻合口9例(9/15);静脉流出道6例(6/15),其中头静脉3例,肱静脉2例,腋静脉1例.首次开通率3个月为40％,6个月为19％,12个月为13％.再次开通率3个月为93％,6个月为88％,12个月为87％.术后平均随访时间为(14.9±5.3)个月,再窄狭率为87％(13/15).术后PTA 36例次,支架内狭窄36％ (13/36);支架远端狭窄8％ (3/36);支架近端狭窄22％(8/36);与支架无关的狭窄33％ (12/36).AVG中位生存时间为25个月.结论 球囊扩张联合覆膜支架植入治疗AVG狭窄技术成功率高,并发症少,首次开通率不高,但再次开通率令人满意.