The use of covered nitinol stents to salvage dialysis grafts after multiple failures

The increasing number of patients requiring hemodialysis and the limited number of access sites have resulted in an increase in multiple graft revisions to maintain access for hemodialysis. Venous outflow or anastomotic stenoses in vascular grafts tend to recur and contribute to the difficulty in maintaining a functioning graft. Thus, extending the life of a failed graft becomes an important objective of this study, which was to assess the use of covered nitinol stents to salvage expanded polytetrafluoroethylene (ePTFE) grafts with venous anastomotic or outflow stenosis that have failed after multiple revisions. This is a review of 8 failed non-autogenous ePTFE grafts with isolated venous anastomotic or proximal outflow stenoses that had undergone multiple previous revisions, had failed percutaneous transluminal angioplasty (PTA), and required placement of a covered nitinol stent. Graft locations were forearm (2), upper arm (4), and femoral (2). The mean number of interventions per patient before stent placement was 5.87 thrombectomies (range 2-28) and 3.38 balloon angioplasties (range 2-19). Five patients had 0.62 interposition grafting and 3 had patch angioplasty. All 8 patients (100%) underwent successful dialysis after thrombectomy and stenting. The primary and secondary patency rates after stent placement were 50% and 75%, and 25% and 75%, at 3 and 6 months, respectively. Percutaneous thrombectomy, balloon angioplasty, and concomitant covered nitinol stent placement extend the function of hemodialysis access grafts that have previously failed multiple times.     

BRAVO I: A pilot study of vascular brachytherapy in polytetrafluoroethylene dialysis access grafts

Hemodialysis vascular access dysfunction owing to stenosis and thrombosis in polytetrafluoroethylene dialysis access grafts is a huge clinical problem for which there are currently no long lasting durable therapies. Vascular brachytherapy has been used successfully for the prevention of coronary restenosis following angioplasty and stent placement. The Beta Radiation for Treatment of Arterial-Venous Graft Outflow I study was a pilot study of vascular brachytherapy in hemodialysis patients with patent but dysfunctional grafts. Twenty-five patients were randomized to receive either radiation therapy (a single dose of 18.4 Gy) or sham radiation, following angioplasty. The primary efficacy end point of the study was target lesion primary patency at 6 months. The primary safety end point was a composite of death, emergency surgery on the graft, venous rupture, or aneurysm formation. Forty-two percent of the radiated grafts achieved the target lesion primary patency end point at 6 months as compared to 0% of the control group (P = 0.015), but this did not translate into an improvement in secondary patency at either 6 or 12 months. Radiation therapy was found to be safe in the setting of hemodialysis vascular access dysfunction. Our results suggest that vascular brachytherapy is an intervention that is worthy of further examination in the setting of non-thrombosed dialysis access grafts.     

Salvage of thrombosed dialysis access grafts with venous anastomosis stents

BACKGROUND: Thrombosis of arteriovenous (AV) grafts caused by stenosis at the venous anastomosis is a well-described problem. Surgical thrombectomy and conventional angioplasty with mechanical thrombectomy have provided good success rates in achieving immediate graft patency but with generally dismal graft survival rates in the range of 11% to 36% at 6 months' follow-up. The role of intravascular stents in patients who have failed angioplasty or surgical revision at the venous anastomosis has not been fully elucidated, particularly in older grafts that have previously undergone multiple procedures. METHODS: In this series, 34 patients had self-expanding nitinol stents placed at the venous anastomosis following graft thrombectomy and angioplasty procedures. Patients were selected for stent placement if conventional angioplasty alone was unsuccessful due to immediate elastic recoil or residual stenosis. All patients were followed after stent placement and evaluated for duration of graft patency and need for repeated endovascular procedures. RESULTS: The average graft age at the time of stent placement was 17.9 months. Eight-eight percent of grafts were functioning at 6 months' follow-up, and 63% of the entire group had survived without the need for additional procedures. Among those with need for repeat interventions, 81% had new lesions outside of the stent, and 57% had new lesions within the stent. In 38% of cases, new stenoses were located both outside and within the stent. Among grafts no longer being used, only 19% of the time was it due to disease recurring within the stent. CONCLUSION: Polytetrafluoroethylene (PTFE) graft longevity is improved when venous anastomosis stenoses are treated with stents in selected cases of older grafts that would have normally undergone abandonment or surgical revision.     

Salvaging prosthetic dialysis fistulas with stents: forearm versus upper arm grafts

OBJECTIVE: We compared results of angioplasty with those of concomitant stent placement to treat thrombosed forearm hemodialysis grafts with results for upper arm grafts. MATERIAL AND METHODS: Between October 1998 and July 2002, stents were deployed in 61 patients undergoing balloon angioplasty because of venous anastomotic stenosis causing graft thrombosis. Stents were used only in cases of inadequate angioplasty results. Twenty-three forearm grafts and 38 upper arm grafts were treated. All procedures were performed in an endovascular operating suite, with fistulography. Primary and secondary patency rates were analyzed and compared for graft location with the life table method. RESULTS: Grafts had undergone a mean of 1.56 previous revisions because of thrombosis (forearm: 1.52, upper arm: 1.58; P = NS). Excluding early thrombosis, a single graft infection was the only procedural complication. Cumulative primary patency rate at 3, 6, and 12 months (from stent placement) was 36.4%, 15.6%, and 0%, respectively, for forearm grafts, which was inferior to the 59.5%, 34.0%, and 17.0% primary patency rate observed for upper arm grafts (P =.0307) Secondary patency rate was 40.9%, 40.9%, and 30.7%, respectively, for forearm grafts, and 64.9%, 42.3%, and 19.7% for upper arm grafts (P = NS). CONCLUSION: Stent deployment can salvage thrombosed dialysis grafts. However, sustained patency occurs infrequently, with better results for upper arm grafts than for forearm grafts. Inasmuch as surgical revision of forearm grafts is usually straightforward, stenting should be reserved for use in high axillary grafts and other sites where surgical repair is difficult.     

Outcomes of thrombosed arteriovenous grafts: comparison of stents vs angioplasty

The usual radiologic approach to thrombosed grafts is a combination of thrombectomy and angioplasty of the underlying lesion. However, the primary (unassisted) graft patency after thrombectomy is quite poor. We evaluated whether graft patency following thrombectomy is improved by placement of a stent in the stenotic lesion. Using a prospective, computerized vascular access database, we identified 14 patients with thrombosed arteriovenous (A-V) grafts treated with a stent at the venous anastomosis (stent group). The outcomes of these grafts was compared to those observed in 34 sex, age-, and date-matched control patients whose thrombosed A-V grafts were angioplastied (control group). Both groups were comparable in age, sex, race, diabetic status, graft age, and number of previous graft interventions. The immediate technical success, as indicated by the post-procedure graft to systemic pressure ratio, was similar in the stent and control groups (0.33+/-0.16 vs 0.41+/-0.17, P=0.14). The primary graft patency (time from thrombectomy to next intervention) was significantly longer for the stent group (median survival, 85 vs 27 days, P=0.02). Assisted or secondary patency (time from thrombectomy to permanent graft failure) was also longer for the stent group (median survival, 1215 vs 46 days, P=0.049). In conclusion, treatment of thrombosed grafts with a stenosis at the venous anastomosis with a stent results in longer primary and secondary graft survival, as compared to treatment with angioplasty. Stent placement may be a useful treatment modality in a subset of patients with thrombosed A-V grafts and stenosis at the venous anastomosis.     

A comparison of patch angioplasty and stenting for axillary venous stenoses of thrombosed hemodialysis grafts

The efficacy of balloon angioplasty with stent placement is compared to surgical patch angioplasty for thrombosed upper arm hemodialysis grafts with stenotic lesions at the venous anastomosis. Patients with thrombosed hemodialysis grafts terminating at the axillary vein were reviewed. Thirty-eight stents were placed after thrombectomy and venous balloon angioplasty in 26 patients. Fifteen case-matched controls underwent 23 polytetrafluoroethylene patch angioplasties for similar lesions. Kaplan-Meier survival analysis was used for statistical comparison. Primary patency for stent placement compared with patch angioplasty was not statistically different at any time through 1-year follow-up (37% vs 55% at 3 months, 25% vs 45% at 6 months, and 25% vs 15% at 12 months, respectively; p = 0.37). Secondary patency rates were slightly better for patch angioplasty compared with stent placement (78% vs 59% at 3 months, 78% vs 48% at 6 months, and 54% vs 32% at 12 months, respectively) however these differences were not statistically significant (p = 0.13). There was no difference in complication rates between groups. Sustained patency is poor for both angioplasty with stent placement and surgical patch angioplasty when revising thrombosed dialysis grafts with anastomotic axillary vein stenosis. These data suggest slightly better patency for the routine use of patch angioplasty for these lesions. However, the endovascular approach appears to be a reasonable alternative when surgical exposure is difficult.     

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.     

Axillary loop grafts for hemodialysis access: midterm results from a single-center study

PURPOSE: This study reports our midterm results with arteriovenous axillary loop grafts (AVALG) and evaluates their role in construction of vascular access for patients on chronic hemodialysis. METHODS: The clinical data of 27 patients who underwent construction of an AVALG for hemodialysis access at our institution between July 2002 and December 2006 were analyzed retrospectively. Outcome measures included graft patency, the complication rate, and the frequency and morbidity of secondary procedures after AVALG creation. The Kaplan-Meier method was used to calculate the primary and secondary patency curves. RESULTS: AVALG was constructed as the first access procedure in eight patients: five patients with no suitable vein to construct an adequate angioaccess on the upper limbs, and three patients with elbow and forearm arteritis. The 19 other patients had all had two to five failed prior vascular accesses leading to exhaustion of venous access sites on the upper extremities (18 cases), or a steal syndrome (one case). No postoperative death occurred, but four patients died of causes unrelated to the intervention between the second and the tenth postoperative months. The mean follow-up was 15 months (range, 2-48 months). The primary patency rate at 12 months and the secondary patency rate at 18 months were 51% and 80%, respectively. Infection (three cases), thrombosis (seven cases), and stenosis of the outflow vein (two cases) were the main complications, occurring in 10 of the 27 patients (41%). Twelve secondary procedures were performed in these 10 patients with little additional morbidity. Five of the 27 patients developed irreversible AVALG occlusion leading to access loss: two patients with concomitant graft infection and three patients with a history of subclavian vein catheterization. CONCLUSION: AVALG may represent a supplementary option for chronic hemodialysis patients with vascular steal or inadequate upper extremity venous access sites.     

Results of aggressive graft surveillance and endovascular treatment on secondary patency rates of Vectra Vascular Access Grafts

OBJECTIVE: The aim of the present study was to determine the effect of an aggressive graft surveillance and endovascular treatment protocol on secondary patency rates of a polyetherurethaneurea vascular access graft, specially designed to provide early access and rapid hemostasis. METHODS: One hundred and ninety Vectra Vascular Access Grafts (C. R. Bard, Inc, Murray Hill, NJ) were placed in 176 patients (78 females and 98 males, mean age 61.7 years). There were 41 forearm grafts, 145 upper arm grafts and four thigh grafts. Graft surveillance was performed by using clinical and hemodialysis parameters to detect a failing/failed graft and followed by endovascular treatment, rheolytic thrombectomy (AngioJet, Possis Medical Inc, Minneapolis, Minn) and/or angioplasty +/- stenting of the anatomical lesion (arterial anastomosis, graft, venous outflow, draining or central veins). RESULTS: Hemodialysis started after a median of 15.5 days, as soon as from the day of the operation in some cases. Bleeding complications occurred in six patients (3.2%), venous hypertension in seven (3.7%), steal syndrome in two (1.1%), neurological complications in two (1.1%), while late infection (range 2.7-14.6 months) was seen in six patients (3.2%). Thrombectomy and angioplasty (median number of sessions 1, interquartile range 1-2) was performed in 43 grafts. Isolated angioplasty, not associated with thrombosis (median number of sessions 1, interquartile range 1-2), was performed in 50 grafts. These interventions increased primary assisted patency from 69% and 63% at 12 and 18 months, respectively to a secondary patency rate of 86%. Taking into account grafts removed for late infection, functional secondary patency rate dropped to 83% and 81%, at 12 and 18 months, respectively. Arterial anastomosis angioplasty was performed more frequently in thrombosed grafts (28.6%) than failing grafts (6.7%), P < .001 and had a significant negative predictive value on secondary patency rates at 12 and 18 months, which were 60.5% compared with 89% for grafts that had no interventions performed (P = .007) and 90.9% for grafts that had any intra-graft, venous outflow, or draining or central vein stenosis treated with angioplasty at any stage (P = .002). Multivariate analysis identified the presence of arterial anastomosis stenosis as the single predictor of secondary patency (relative risk 0.247, P = .002). CONCLUSIONS: Aggressive graft surveillance and endovascular treatment increases significantly secondary patency rates of Vectra Vascular Access Grafts. Longer follow-up will determine the effectiveness of this policy. The role of inflow stenosis on graft longevity and alternative treatment options warrant further investigation.     

A preliminary investigation of balloon angioplasty versus surgical treatment of thrombosed dialysis access grafts

It has been estimated that 180,000 patients in the United States have end-stage renal disease requiring hemodialysis, and this number is currently increasing at a rate of 10 per cent per year. With the growing number of patients requiring hemodialysis the insertion and maintenance of dialysis access has become a common task for vascular surgeons. In fact dialysis access is now the most common vascular operation and may account for as much as 40 to 50 per cent of the practice of a busy vascular surgeon. The two major techniques for repairing thrombosed dialysis access grafts are open surgical revision and balloon angioplasty. Surgical revisions of access sites include patch angioplasty and interposition jump grafts. Balloon angioplasty involves declotting the graft mechanically or chemically followed by dilation of the stenotic segment by an angioplasty balloon under fluoroscopy. Few studies have compared the two methods of repair, and the studies that have been done reveal conflicting results. A retrospective chart review of patients treated at the New Hanover Regional Medical Center for repair of thrombosed dialysis access grafts was conducted. The final sample available for analysis consisted of 16 patients with balloon angioplasty and 44 patients with surgical revision. These two groups were compared in terms of demographics, past medical history, surgery time, complications, length of stay, length of graft patency, and typical costs. Overall balloon angioplasty as compared with surgical revision was associated with longer patency (5.5 vs 3.2 months), shorter surgical time (43.9 vs 64.5 minutes), shorter length of hospital stay (less than one day vs one day or more), and fewer complications (12% vs 30% of the patients). We concluded from this analysis that endovascular treatment of thrombosed dialysis grafts is an acceptable alternative to surgical revision and should be the first option after primary failure of the grafts caused by stenotic lesions.     

Vascular rupture during angioplasty of hemodialysis raft-related stenoses

Purpose: To retrospectively determine the incidence and outcome of angioplasty-induced ruptures that occurred during treatment of hemodialysis graft-related stenoses. Materials and Methods: During a five year period 1222 patients with dysfunctional or thrombosed polytetrafluoroethylene (PTFE) hemodialysis grafts underwent angioplasty procedures at our institution. Angioplasty-induced vascular ruptures occurred in 24 (2.0%) patients. The locations of these ruptures were: basilic vein (10), venous anastomosis (7), cephalic vein (5), brachial vein (1) and intragraft (1). The mean length of the treated stenoses was 2.4 centimeters. Results: Manual compression was used to treat the vascular rupture in ten patients. One patient was treated with endovascular balloon tamponade and one patient underwent stenting of the rupture site. Despite the rupture, 15 patients had completion of the angioplasty procedure. In nine patients the procedure was abandoned due to persistent stenosis at the rupture site. There were no major complications as a result of these ruptures. Follow-up was available in ten of these patients. All ten underwent at least one successful hemodialysis treatment. In five of these patients the hemodialysis graft failed within 30 days after the rupture. The mean primary patency following rupture in the ten patients with follow-up was 87.5 days (range 5 - 225 days). Conclusion: The incidence of angioplasty-induced vascular rupture of hemodialysis-related stenoses is low and despite the injury, the majority (62%) of procedures can be completed. However, in our experience the long-term patency of the vascular access was suboptimal.     

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。     

Prospective,randomized evaluation of a cuffed expanded polytetrafluoroethylene graft for hemodialysis vascular access

BACKGROUND: A cuffed expanded polytetrafluoroethylene (ePTFE) hemodialysis graft was developed to address the problem of recurrent stenosis at the graft-vein anastomosis. The purpose of this study was to compare graft patency and blood flow rates of cuffed and noncuffed (standard) ePTFE grafts placed for hemodialysis access. METHODS: Forty-eight patients were prospectively randomized and followed for up to 24 months after placement of a cuffed or standard ePTFE graft for hemodialysis access. Study end points included time to graft failure and blood flow rates on hemodialysis. RESULTS: Risk factors for graft failure were similar in both groups. However, the overall incidence of graft failure was significantly lower in the cuffed ePTFE graft group (P =.039). Graft patency rates in the cuffed versus standard groups were 64% versus 32% at 12 months (P =.037) and 58% versus 21% at 24 months (P =.0213). No cuffed ePTFE graft failed as a result of venous outflow stenosis. Average graft flow rates were similar when first measured 3 months postoperatively (845 mL/min, cuffed vs 715 mL/min, standard; P =.51) but declined more rapidly in the standard group (12 months, 623 vs 253 mL/min [P =.037]; 24 months, 531 vs 121 mL/min [P =.012]). CONCLUSIONS: The cuffed ePTFE graft was associated with increased blood flow rates during hemodialysis and improved graft patency compared with a standard ePTFE graft. Our results suggest a beneficial effect of the cuffed venous geometry for hemodialysis vascular access.     

A randomized controlled trial of drug-coated balloon angioplasty in venous anastomotic stenosis of dialysis arteriovenous grafts

ObjectivePaclitaxel-coated balloons are used to reduce neointimal hyperplasia in native arteriovenous (AV) fistulas. However, no study specifically evaluated their effect on venous anastomotic stenosis of dialysis grafts. We aimed to compare the efficacy of angioplasty with drug-coated balloons (DCBs) and angioplasty with conventional balloons (CBs) for venous anastomotic stenosis in dysfunctional AV grafts.MethodsIn this investigator-initiated, single-center, single-blinded, prospective randomized controlled trial, we randomly assigned 44 patients who had venous anastomotic stenosis to undergo angioplasty with DCBs (n = 22) or CBs (n = 22) from July 2015 to August 2018. Access function was observed per the hemodialysis center's protocols; ancillary angiographic follow-up was performed every 2 months for 1 year after the interventions. The primary end point was target lesion primary patency at 6 months. Secondary outcomes included anatomic and clinical success after angioplasty, circuit primary patency at 6 months and 1 year, and target lesion primary patency at 1 year.ResultsAt 6 months, target lesion primary patency in the DCB group was significantly greater than that in the CB group (41% vs 9%; hazard ratio [HR], 0.393; 95% confidence interval [CI], 0.194-0.795; P = .006), as was the primary patency of the entire access circuit (36% vs 9%; HR, 0.436; 95% CI, 0.218-0.870; P = .013). At 1 year, the target lesion primary patency in the DCB group remained greater than that in the CB group (23% vs 9%; HR, 0.477; 95% CI, 0.243-0.933; P = .019) but not the primary patency of the access circuit (14% vs 9%; HR, 0.552; 95% CI, 0.288-1.059; P = .056). No difference in anatomic or clinical success was observed; no major complications were noted.ConclusionsAngioplasty with DCBs showed a modest improvement in primary patency of venous anastomotic stenosis and all dialysis AV grafts at 6 months. The short-term benefit was not durable to 1 year, and reinterventions were eventually needed.     

A Meta‐analysis of Stent Placement vs. Angioplasty for Dialysis Vascular Access Stenosis

Dysfunction of arteriovenous fistulas (AVF) and arteriovenous grafts (AVG) contribute significantly to morbidity and hospitalization in the dialysis population. Despite advances in endovascular techniques, the incidence of vascular access stenosis remains problematic. Currently, the role of endovascular stent placement in the treatment of vascular access stenosis is poorly defined. This meta‐analysis compares the primary patency rates of stenotic vascular access treated with stent placement vs. angioplasty. We searched Medline for English language publications from 1980 through December 2013, along with national conference proceedings and reference lists of all included publications. Inclusion criteria were a measure of primary patency, secondary patency, or access dysfunction. Studies were excluded if they were not in English or if they included pediatric patients. Ten studies with a total of 860 subjects met the inclusion criteria, including six experimental studies and four observational studies. There was significantly higher overall primary patency in those receiving stent placement than in those treated with angioplasty (pooled relative risk [RR] = 0.79; 95% confidence interval [CI]: 0.65–0.96). The estimate did not differ by study design. The effect of treatment differed significantly (p = 0.001) by the type of stents used, however. In studies including nitinol stents (six studies, 678 patients), 6‐month patency was significantly better for stent placement than angioplasty (pooled RR = 0.67; 95% CI: 0.54–0.84), whereas there was no significant differences between stent placement and angioplasty in those studies using bare metal stents exclusively (four studies, 182 patients; pooled RR = 1.09; 95% CI: 0.91–1.32). There was significant heterogeneity between studies (I² = 70.6%; p < 0.0001). Our results suggest that stent placement may confer an advantage over balloon angioplasty in primary patency of dialysis access stenoses.     

Randomized comparison of 6-mm straight grafts versus 6- to 8-mm tapered grafts for brachial-axillary dialysis access

OBJECTIVE: This report presents the results of a prospective randomized study that compared 2 grafts of different diameter: 6 mm, and 8 mm tapered to 6 mm at the arterial site, placed in the upper arm for hemodialysis in a selected population of patients younger than 71 years without diabetes. METHODS: Seventy consecutive patients younger than 71 years without diabetes who required an upper arm graft between January 1997 and January 2002 and without previous access in the same limb were randomly allocated to receive either a 6-mm graft or 6- to 8-mm graft. Graft flow was measured every 3 months with the Doppler dilution technique. When access flow was less than 600 mL/min, fistulography was performed, and any stenosis was surgically treated with venous outflow replacement. Thrombectomy and associated stenosis treatment in the same stage was performed in all cases immediately after detection of thrombosis. Complication rate, and primary, assisted primary, and secondary patency rates were compared between the two groups with the Student t test and life table analysis. RESULTS: Mean access flow was 975 mL/min for 6-mm grafts (range, 600-1500 mL/min; 95% confidence interval [CI], 889-1070), and for 6- to 8-mm grafts was 1397 mL/min (range, 1122-2700 mL/min; 95% CI, 1122-1672). This difference was significant (P <.01). Complication rate was 0.45 episodes per graft-year in 6-mm grafts, and 0.19 episodes per graft-year in 6- to 8-mm grafts (P <.01). At 1, 2, and 3 years, primary patency rates were 62%, 58%, and 44%, respectively, for 6-mm grafts, and 85%, 78%, and 73% for 6- to 8-mm grafts; log-rank comparison between curves was P =.0259. At 1, 2, and 3 years, secondary patency rates were 85%, 85%, and 85%, respectively, for 6-mm grafts, and 90%, 90%, and 90% for 6- to 8-mm grafts; log-rank comparison between curves was not significant, at P =.0603. At 1, 2, and 3 years, assisted primary patency rates were 84%, 79%, and 76%, respectively, for 6-mm grafts, and 90% for 6- to 8-mm grafts; log-rank comparison was P =.0414. CONCLUSIONS: The results of this study show an advantage in terms of primary and assisted primary patency rates, and complication rate for upper arm grafts with diameter 6 mm to 8 mm over grafts with 6-mm diameter in a patient population younger than 70 years without diabetes. The finding of a similar secondary patency rate in both groups is probably due to the surveillance program with sequential measurement of access flow and prompt surgical treatment of stenosis. However, we needed twice the number of rescue procedures in 6-mm grafts to achieve a similar patency rate as with large-bore grafts. These study results must be carefully evaluated, taking into consideration the small number of patients and the selected patient population.     

Equivalent secondary patency rates of upper extremity Vectra Vascular Access Grafts and transposed brachial-basilic fistulas with aggressive access surveillance and endovascular treatment

OBJECTIVES: The 2006 update of the DOQI guidelines has stated that in patients with end-stage renal disease, autogenous radial-cephalic, or brachial-cephalic fistulas are the preferred access modalities, followed by transposed brachial-basilic (TBB) fistulas and prosthetic arteriovenous (AV) grafts. AV grafts are in general least preferred; however, there is very limited data comparing directly the last two modalities. The aim of the present study is to compare outcomes of the TBB fistula and the Vectra Vascular Access Graft. METHODS: Seventy-six patients had a prosthetic brachial-axillary Vectra graft placed, while in 41 patients brachial-basilic upper arm transposition was performed. Graft surveillance to detect a failing/failed access was followed by endovascular treatment, rheolytic thrombectomy (AngioJet, Possis Medical), and/or angioplasty +/- stenting of the responsible anatomical lesion(s). RESULTS: Use of Vectra grafts and TBB fistulas started after a median (interquartile range) of 14 (7-30) and 70 (52-102) days, respectively (P < .001), as early as the operative day in some patients with grafts. Postoperative complications were more frequent in TBB fistulas and late complications (mainly access thrombosis) in Vectra grafts. Total number of thrombectomy sessions performed for graft or fistula occlusion was 45 and 7, respectively (P = .032); total number of isolated angioplasty sessions, performed for failing graft or fistula was 31 and 45, respectively (P = .004). Although primary patency of the two access modalities was equivalent, primary assisted patency was significantly reduced in Vectra grafts (70% at 12 months and 58% at 18 months), compared with TBB fistulas (82% at 12 months and 78% at 18 months, P = .033); however, as a result of endovascular intervention, secondary patency rates at 12 months (87% vs 88%) and 18 months (87% vs 83%) were equivalent (P = .91). Presence of arterial anastomosis stenosis treated with angioplasty at any stage had a significant negative predictive value on secondary patency rates at 12 and 18 months which were 61%, compared with 96% for Vectra grafts that had any intra-graft, venous outflow, draining or central vein stenosis treated with angioplasty at any stage (P = .010). CONCLUSIONS: Aggressive graft surveillance and endovascular treatment methods can yield equivalent long-term secondary patency rates between Vectra graft and TBB fistulas. The advantage of earlier use of Vectra graft must be balanced against the need for more frequent secondary interventions and the risk of graft infection.     

Balloon angioplasty as a treatment of failing infrainguinal autologous vein bypass grafts

PURPOSE: The purpose of this study was to evaluate the role of balloon angioplasty in the treatment of failing infrainguinal vein bypass (IVB) grafts. METHODS: A retrospective chart review of patients undergoing revision of a failing IVB graft by vascular surgeons at a tertiary care center from 1990 to 2001 was performed. Failing bypass grafts were identified by routine duplex scan surveillance and physical examination. The criteria for endovascular intervention varied on the basis of surgeon preferences and time period; factors considered when choosing balloon angioplasty included significant comorbidities that precluded operative intervention, the lack of adequate conduit for surgical revision, or poor accessibility of the stenotic lesion. Data recorded included demographic patient data, type of IVB graft, patency status, further procedures performed, and all complications and mortalities. Cumulative primary and assisted patency rates were calculated by using Kaplan-Meier life-table analysis. RESULTS: A total of 45 balloon angioplasties were performed in 36 patients. There were 36 angioplasties of vein bypass grafts, and additional balloon angioplasties were performed on nine of these patients. Locations of IVB grafts included femoropopliteal (13 patients), femorodistal (13), and popliteal to distal (10). Initial success was achieved in 33 of 36 vein bypass grafts (91.7%). In these bypass grafts, the stenotic lesions were identified and treated at the proximal anastomosis (3 patients), mid-bypass graft (6 patients), and distal anastomosis (27 patients). Autogenous vein was used for all bypass grafts. Cumulative vein bypass graft (life-table analysis) primary patency rates (those free of occlusion or bypass graft threatening stenosis) were 74.2% at 6 months, 62.7% at 12 months, and 58.2% at 24 months. Repeat interventions included surgical thrombectomy with vein patch angioplasty or bypass graft revision, as well as repeat balloon angioplasty with or without thrombolysis. Cumulative assisted vein bypass graft patency rates (those free of occlusion or bypass graft threatening stenosis) were 87.0%, 83.2%, and 78.9% at 6, 12, and 24 months, respectively. Two patients (4%) developed thigh hematomas; no other procedure-related complications were noted, and there were no deaths in the perioperative period. CONCLUSION: Balloon angioplasty of failing infrainguinal vein bypass grafts can be successfully performed with a low rate of complications. Acceptable short-term patency can be achieved. This procedure should be considered as an initial option in failing IVB grafts.     

Treatment of refractory central vein stenosis in hemodialysis patients with stents

Central venous stenosis is a frequent complication in hemodialysis patients, which can manifest clinically with ipsilateral upper extremity edema. When symptomatic, it is usually treated by percutaneous transluminal angioplasty. When angioplasty is unsuccessful, stent deployment is a therapeutic option. The goal of the present study was to evaluate the primary and secondary patency of refractory central vein stenosis after treatment with a stent. Using a prospective vascular access database we retrospectively identified 23 patients presenting with unilateral upper extremity edema and a significant (> 50%) central vein stenosis, who underwent stent placement due to refractory stenosis following angioplasty. The primary (unassisted) central vein patency was determined from the initial intervention to the next angioplasty for recurrent central vein stenosis, and the secondary (assisted) patency from the initial intervention to permanent central vein occlusion. An immediate technical success was achieved in all patients after the stent deployment. However, the median primary central vein patency was only 138 days, with a 19% patency at 1 year. Recurrence of ipsilateral edema was always due to in-stent restenosis. The median secondary central vein patency was 1036 days, with a 64% patency at 1 year. In patients with symptomatic central vein stenosis that is refractory to percutaneous transluminal angioplasty, stent deployment provides short-term relief of the stenosis and ipsilateral upper extremity edema. However, long-term symptomatic relief can be achieved with multiple subsequent interventions in many patients.     

Regular ultrasonographic screening significantly prolongs patency of PTFE grafts

BACKGROUND: Polytetrafluoroethylene (PTFE) dialysis grafts have considerably shorter patency than native arteriovenous fistulas, despite the use of a complex of screening monitoring methods (venous pressure, access flow). PTFE grafts are used often in subjects with depleted subcutaneous veins after previous abandoned accesses, so keeping the access patent is crucial. We hypothesized that regular duplex Doppler ultrasound screening for access stenoses, together with their sooner treatment, would prolong PTFE graft patency. METHODS: We performed a randomized, prospective study of PTFE grafts' cumulative patency in 192 subjects. In group 1, regular ultrasound examinations performed every 3 months was added to traditional screening (i.e., regular access examination at hemodialysis unit, monitoring of venous pressure and access flow). Group 2 was screened only traditionally (without ultrasound). Interventions of suspected stenoses were indicated by nephrologists, vascular surgeon, and, in group 1, also by ultrasonography. Classic ultrasound criteria for significant stenosis were used, even if the access flow had not been decreased. The mean follow-up lasted 392 +/- 430 days. RESULTS: Groups were similar with respect to age, gender, diabetes status, and number of previous abandoned accesses. Group 1 had significantly longer access patency (P < 0.001). Number of interventions per graft was 2.1 +/- 1.8 and 1.3 +/- 1.0 in group 1 and group 2. CONCLUSIONS: Regular screening duplex Doppler ultrasonography results in significantly longer PTFE graft patency due to early detection of access stenosis and, thus, more frequent elective interventions of access stenoses.