Best threshold for diagnosis of stenosis or thrombosis within six months of access flow measurement in arteriovenous fistulae

Canadian clinical practice guidelines recommend performing angiography when access blood flow (Qa) is <500 ml/min in native vessel arteriovenous fistulae (AVF), but data on the value of Qa that best predicts stenosis are sparse. Because correction of stenosis in AVF improves patency rates, this issue seems worthy of investigation. Receiver-operating characteristic curves were constructed to examine the relationship between different threshold values of Qa and stenosis in 340 patients with AVF. Stenosis was defined by the composite outcome of access failure or angiographic stenosis occurring within 6 mo of the first Qa measurement. The Qa value was then classified as true negative, true positive, false negative, or false positive for stenosis. An additional analysis was performed in which Qa was corrected for systolic BP before assigning it to one of the four diagnostic categories. The area under the curve for the composite definition of stenosis was 0.86. Graphically, Qa thresholds of <500 and <600 ml/min had similar efficacy for detecting stenosis or access failure within 6 mo, and both seemed superior to <400 ml/min. However, the frequency of the composite definition of stenosis among AVF with Qa between 500 and 600 ml/min was only 6 (25%) of 24, as compared with 58 (76%) of 76 when Qa was <500 ml/min. This suggests that most lesions that would be found using a threshold of <600 ml/min occurred in AVF with Qa <500 ml/min and that the small gain in sensitivity associated with the <600-ml/min threshold would be outweighed by the reduced specificity compared with <500 ml/min. Correcting Qa for BP did not improve diagnostic performance or change these results, which were consistent in several sensitivity analyses. Qa measurements seemed to predict stenosis or incipient access failure equally well in groups defined by diabetic status, gender, and AVF location. In conclusion, it was found that Qa <500 ml/min seems to be the most appropriate threshold for performing angiography in patients with native vessel AVF. It is recommended that clinicians arrange angiography when Qa is <500 ml/min in AVF.     

Short- and long-term functional effects of percutaneous transluminal angioplasty in hemodialysis vascular access

The efficacy of percutaneous transluminal angioplasty (PTA) is usually expressed as the angiographic result. Access flow (Qa) measurements offer a means to quantify the functional effects. This study was performed to evaluate the short-term functional and angiographic effects of PTA and to determine the longevity of the functional effects during the follow-up period. Patients with an arteriovenous graft (AVG) or an arteriovenous fistula (AVF) who were eligible for PTA (Qa values of <600 ml/min) were included. Ultrasound-dilution Qa measurements were obtained shortly before PTA and periodically after PTA, beginning 1 wk after the procedure. The short-term effects were expressed as the increase in Qa and the reduction of stenosis. The long-term effects were expressed as patency and the decrease in Qa after PTA. Ninety-eight PTA procedures for 60 patients (65 AVG and 33 AVF) were analyzed. Qa improved from 371 +/- 17 to 674 +/- 30 ml/min for AVG and from 304 +/- 24 to 638 +/- 51 ml/min for AVF (both P < 0.0001). In 66% (AVG) and 50% (AVF) of cases, Qa increased to levels of >600 ml/min. The degree of stenosis decreased from 65 +/- 3 to 17 +/- 2% for AVG and from 72 +/- 5 to 23 +/- 7% for AVF (both P < 0.005). The reduction of stenosis was not correlated with DeltaQa (r(2) = 0.066). Six-month unassisted patency rates after PTA were 25% for AVG and 50% for AVF. The decreases in Qa were 3.7 +/- 0.8 ml/min per d for AVG and 1.8 +/- 0.9 ml/min per d for AVF. Qa values before PTA and DeltaQa were correlated with the subsequent decrease in Qa (P < 0.005). In conclusion, Qa increases after PTA but, in a substantial percentage of cases, not to levels of >600 ml/min. Qa values before PTA and the increase in Qa were correlated with long-term outcomes, whereas angiographic results were not. These data, combined with literature data, suggest that there is optimal timing for PTA.     

Outpatient treatment of arterial inflow stenoses of dysfunctional hemodialysis access fistulas by retrograde venous access puncture and catheterization

OBJECTIVE: To determine the feasibility of endovascular treatment of inflow stenoses in arteriovenous fistulae (AVFs) through retrograde venous access catheterization. METHODS: We included all 22 dysfunctional AVFs with arterial inflow stenoses at access imaging between January 2002 and September 2006. Following retrograde venous access puncture, an interventional radiologist intended to cross the arteriovenous anastomosis and advance a catheter into the aortic arch. After depiction of the complete vascular access tree, angioplasty and/or stent placement was aimed for stenoses with a >50% luminal diameter reduction at digital subtraction angiography (DSA). RESULTS: In one radiocephalic AVF, a catheter could not be positioned into the aortic arch after retrograde venous access puncture. DSA depicted 28 inflow stenoses in the remaining 21 patients (11 radiocephalic AVFs and 10 brachiocephalic AVFs). Clinical improvement was obtained in 18 out of 19 patients with a technically successful intervention (<30% residual stenosis after angioplasty or stent placement). Following endovascular therapy, access flow of 12 patients with a low flow access improved from 431 +/- 150 ml/min to 818 +/- 233 ml/min, and four patients with steal symptoms became symptom free. One nonmaturing fistula could be salvaged by angioplasty, and access cannulation problems were solved in another patient following angioplasty. Brachial artery stent placement did not reduce steal symptoms in one case, whereas two patients, in whom stent placement was not thought desirable, showed a >30% residual arterial stenosis after angioplasty. No complications were observed at DSA and endovascular intervention. CONCLUSION: Retrograde venous access puncture and catheterization, as an alternative to a potentially more hazardous brachial artery or more invasive femoral artery approach, should be considered for the visualization of the arterial inflow and endovascular treatment of inflow stenoses.     

Monthly access flow monitoring with increased prophylactic angioplasty did not improve fistula patency

BACKGROUND: Regular access monitoring is recommended to detect and treat access stenosis in order to prevent access thrombosis and failure. METHODS: In 1999, we instituted monthly access blood flow monitoring using the ultrasound dilution technique (UDT). In a sequential observational trial, 222 patients were studied for the impact of UDT monitoring on patency of their first arteriovenous autogenous fistula. Group 1, the historic group (before 1999), had 146 arteriovenous fistulas (50.7% upper arm), followed for 259 access-years. Group 2, the UDT-monitored group, had 76 arteriovenous fistulas (60.5% upper arm), followed for 123 access-years. Decision to refer for angiography was based on clinical criteria for group 1, and clinical criteria plus results of UDT flow monitoring in group 2. RESULTS: Cumulative patency was longer (P < 0.01) and the thrombosis rate was lower (P < 0.05) in group 2. However, the improvement occurred prior to initiation of UDT flow monitoring. Comparing outcomes in group 2 patients whose fistula survived to start flow monitoring with group 1 patients whose fistula survived at least 160 days (the median time to starting UDT monitoring in group 2), there was a sevenfold increase in angioplasty procedures (0.67 vs. 0.09 per access-year) but no improvement in the thrombosis rate or cumulative fistula patency. CONCLUSION: UDT monitoring increased the rate of angioplasty procedures and thereby shortened primary unassisted patency, but did not decrease the thrombosis rate or improve cumulative fistula patency.     

Can blood flow surveillance and pre-emptive repair of subclinical stenosis prolong the useful life of arteriovenous fistulae? A randomized controlled study.

BACKGROUND: Stenosis is the main cause of arteriovenous fistula (AVF) failure. It is unclear, however, if surveillance for stenosis enhances AVF function and longevity and if there is an ideal time for intervention. METHODS: In a 5-year randomized, controlled, open trial we compared blood flow surveillance and pre-emptive repair of subclinical stenoses (one or both of angioplasty and open surgery) with standard monitoring and intervention based upon clinical criteria alone to determine if the former prolonged the longevity of mature forearm AVFs. Surveillance with blood pump flow (Qb) monitoring during dialysis sessions and quarterly shunt blood flow (Qa) or recirculation measurements identified 79 AVFs with angiographically proven, significant (>50%) stenosis. The AVFs were randomized to either a control group (intervention done in response to a decline in the delivered dialysis dose or thrombosis; n = 36) or to a pre-emptive treatment group (n = 43). To evaluate a possible relationship between outcome and haemodynamic status of the access, AVFs were divided into functional and failing subgroups, according to Qa values higher or lower than 350 ml/min or the absence or presence of recirculation. RESULTS: A Kaplan-Meier analysis showed that pre-emptive treatment reduced failure rate (P = 0.003) and the Cox hazards model identified treatment (P = 0.009) and higher baseline Qa (P = 0.001) as the only variables associated with favourable outcome. Primary patency rates were higher in treatment than in control AVFs in both functional (P = 0.021) and failing subgroups (P = 0.005). They were also higher in functional than in failing AVFs in both control (P<0.001) and treatment groups (P = 0.023). Access survival was significantly higher in pre-emptively treated than in control AVFs (P = 0.050), a higher post-intervention Qa being the only variable associated with improved access longevity (P = 0.044). Secondary patency rates were similar in pre-emptively treated and control AVFs in both functional (P = 0.059) and failing subgroups (P = 0.394). They were also similar in functional and failing AVFs in controls (P = 0.082), but were higher in pre-emptively treated functional AVFs than in pre-emptively treated failing AVFs (P = 0.033) or in the entire control group (P = 0.019). CONCLUSIONS: We provide evidence that active blood flow surveillance and pre-emptive repair of subclinical stenosis reduce the thrombosis rate and prolong the functional life of mature forearm AVFs. We also show that Qa is a crucial indicator of access patency and a Qa >350 ml/min portends a superior outcome with pre-emptive action in AVFs.     

Native arteriovenous fistulas: correlation of intra-access blood flow with characteristics of stenoses found during diagnostic angiography

Surveillance of the intra-access blood flow (Qa) has improved identification of thrombosis risk (Qa < or = 500 ml/minute), and these patients are referred for angiogram and angioplasty. The purpose of this study was to correlate the Qa with patient and stenotic lesion characteristics both before and after angioplasty in a retrospective cohort of 210 patients who were preselected on the basis of reduced Qa (369 +/- 121 ml/minute). Angiograms revealed a total of 643 stenoses, and all patients had at least one significant stenosis (>50% luminal narrowing). There was no significant association between the preangioplasty Qa and the number, location, or length of stenoses, but there was a significant negative correlation between the degree of stenosis and the preangioplasty Qa. Five hundred eighty stenoses in 190 patients were treated with angioplasty; the postangioplasty Qa was 633 +/- 208 ml/minute. Of the residual stenoses, all had less than 50% narrowing. There was no correlation between the postangioplasty Qa and the length or degree of stenoses, but there was a significant negative correlation between the postangioplasty Qa and the number of stenoses. We conclude that the primary determinant of reduced preangioplasty Qa is the degree of stenosis, when stenoses are over 50%, whereas the primary determinant of reduced postangioplasty Qa is the number of stenosis. For patients with two or more residual stenoses and failure to achieve Qa > 500 p;ml/minute postangioplasty, the alternative procedure is a prompt surgical revision in order to maintain the goal of access patency.     

Predictive value of access blood flow and stenosis in detection of graft failure

AIMS: Low access flow and the diagnosis of high degrees of venous stenosis have been recommended as indications for prophylactic angioplasty. However, recent studies have shown that prophylactic angioplasty for > 50% stenosis did not prolong graft patency, and that a single flow measurement may not accurately predict graft failure. In this study we compared the value of monthly measurement of access flow and of the maximal degree of stenosis in the detection of graft failure over a three-month period. METHODS: Thirty-nine hemodialysis patients with polytetrafluoroethylene (PTFE) grafts were evaluated by Doppler ultrasound at monthly intervals for three months. Graft failures were defined as thrombosis, or surgical and angioplastic revisions required because of the presence of access recirculation, and patients with graft failure were followed within the subsequent one-month periods of observation. RESULTS: Twelve graft failures occurred during the three-month period of observation. The risk for subsequent graft failure significantly increased at flows < 300 ml/min. Nine (20%) graft failures occurred with stenoses of 30 to 50%, and three (13%) with stenoses of> 50%. The grafts that failed in the second and the third study months had a 25.8% (380 +/- 62 vs. 287 +/- 190 ml/min, p < 0.05) and a 36.5% (393 +/- 142 vs. 226 +/- 41 ml/min, p < 0.05) decrease in access flow, respectively. There was no significant change in access flow for the grafts patent throughout the study (911 +/- 333, 794 +/- 302, and 919 +/383 ml/min, p = ns). No significant increases in maximal stenosis were found for the grafts that failed in the second month (44 +/- 6.1 vs. 48 +/- 15%, p = ns) and the third month (48 +/- 9 vs. 51 +/- 16%, p = ns). There were no significant changes in the maximum stenosis for the grafts patent throughout the three-month study periods (37 +/- 15,43 +/- 11, and 44 +/- 15%, p = ns). CONCLUSIONS: Access flow is a more sensitive predictor of graft failure than stenosis. Examination of trend in decline of access flow is a more powerful indicator to detect graft dysfunction than an individual single flow value.     

The role of surveillance in mature arteriovenous fistula management

The existing guidelines recommend arteriovenous fistulae (AVF) surveillance by access blood flow (Qa) measurement and the correction of hemodynamically significant stenoses to prolong access survival. Unfortunately, many studies supporting these recommendations are inadequate methodologically; therefore, both the optimal criteria for surveillance and the value of preventive stenosis repair in AVF remain controversial. Recent literature confirms that Qa measurement allows an accurate identification of both stenosis (area under the curve (AUC) ranging from 0.80-0.93) and access at risk of failure (AUC ranging from 0.82-0.98) in AVFs and suggests a Qa <700-1000 ml/min and/or a reduction in Qa >25% as optimal predictors for stenosis and a Qa <400 ml/min for incipient thrombosis. Recent prospective studies evaluated whether Qa surveillance could improve AVF patency rates compared to monitoring based on clinical and dialysis-related criteria alone. The majority of studies have historical, rather than concurrent, control groups and provide conflicting results, some showing a reduction and some showing no change in thrombosis rates by Qa monitoring. On the other hand, the few randomized controlled studies available show that Qa surveillance, when coupled with preemptive intervention, reduces the already low thrombosis rate in AVF and suggest that the functional access life can be prolonged. However, there is still the need for additional methodologically adequate studies to understand fully the role of surveillance in AVF management.     

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.     

Far-infrared therapy: a novel treatment to improve access blood flow and unassisted patency of arteriovenous fistula in hemodialysis patients

Vascular access malfunction, usually presenting with an inadequate access flow (Qa), is the leading cause of morbidity and hospitalization in hemodialysis (HD) patients. Many methods of thermal therapy have been tried for improving Qa but with limited effects. This randomized trial was designed to evaluate the effect of far-infrared (FIR) therapy on access flow and patency of the native arteriovenous fistula (AVF). A total of 145 HD patients were enrolled with 73 in the control group and 72 in the FIR group. A WS TY101 FIR emitter was used for 40 min, and hemodynamic parameters were measured by the Transonic HD(02) monitor during HD. The Qa(1)/Qa(2) and Qa(3)/Qa(4) were defined as the Qa measured at the beginning/at 40 min later in the HD session before the initiation and at the end of the study, respectively. The incremental change of Qa in the single HD session with FIR therapy was significantly higher than that without FIR therapy (13.2 +/- 114.7 versus -33.4 +/- 132.3 ml/min; P = 0.021). In comparison with control subjects, patients who received FIR therapy for 1 yr had (1) a lower incidence (12.5 versus 30.1%; P < 0.01) and relative incidence (one episode per 67.7 versus one episode per 26.7 patient-months; P = 0.03) of AVF malfunction; (2) higher values of the following parameters, including Delta(Qa(4) - Qa(3)) (36.2 +/- 82.4 versus -12.7 +/- 153.6 ml/min; P = 0.027), Delta(Qa(3) - Qa(1)) (36.3 +/- 166.2 versus -51.7 +/- 283.1 ml/min; P = 0.035), Delta(Qa(4) - Qa(2)) (99.2 +/- 144.4 versus -47.5 +/- 244.5 ml/min; P < 0.001), and Delta(Qa(4) - Qa(2)) - Delta(Qa(3) - Qa(1)) (62.9 +/- 111.6 versus 4.1 +/- 184.5 ml/min; P = 0.032); and (3) a better unassisted patency of AVF (85.9 versus 67.6%; P < 0.01). In conclusion, FIR therapy, a noninvasive and convenient therapeutic modality, can improve Qa and survival of the AVF in HD patients through both its thermal and its nonthermal effects.     

Economic implications of screening strategies in arteriovenous fistulae

Practice guidelines recommend performing angiography in arteriovenous fistulae (AVF) when access blood flow (Qa) is < 500 ml/min, but a Qa threshold of <750 ml/min is more sensitive for stenosis. No economic evaluation has evaluated the optimal Qa threshold for angiography in AVF, or Determined whether screening AVF is more economically efficient than intervening only when AVF is thrombosed. We compared two screening strategies using Qa thresholds of <750 and <500 ml/min, respectively, with no access screening. Expected per-patient access-related costs (in 2002 Canadian dollars) were $3910, $5130, and $5250 in the no screening, QA500, and QA750 arms, respectively over 5 years. Notably, screening strategies did not reduce expected access-related costs under any clinically plausible scenario. The cost to prevent one episode of AVF failure appeared to be approximately $8000-$10,000 over 5 years for both screening strategies, compared with no screening. Although the incremental cost effectiveness of screening (compared to no screening) was similar in the base case for the QA500 and QA750 strategies, the relative economic attractiveness of the QA750 strategy was adversely affected under several plausible scenarios. Also, the QA750 strategy would require many additional angiograms to prevent an additional episode of AVF failure compared with the QA500 strategy. Screening of AVF resulted in a modest increase in net costs and seems to require a net expenditure of approximately $9000 to prevent one episode of AVF failure. If screening is adopted, our findings suggest that angiography should be performed when Qa is <500 rather than <750 ml/min, especially when access to angiography is limited.     

The natural history of autogenous radio-cephalic wrist arteriovenous fistulas of haemodialysis patients: a prospective observational study.

BACKGROUND: Clinical practice guidelines have supported vascular access surveillance programmes on the premise that the natural history of the vascular access will be altered by radiological or surgical interventions after vascular access dysfunction is detected. The primary objective of this study was to assess the actual risk of thrombosis of autogenous radio-cephalic (RC) wrist arteriovenous fistulas (AVFs) without any pre-emptive interventions. METHODS: We enrolled 52 randomly selected adult Caucasian prevalent haemodialysis (HD) patients, all with autogenous RC wrist AVFs, into this prospective, observational study aimed to follow the natural history of their AVFs for 4 years. The protocol prescribed avoiding any surgical or interventional radiological procedures until access failure (AVF thrombosis or a vascular access not assuring a single-pool Kt/V > or =1.2). The subjects underwent yearly assessments of vascular access blood flow rate by means of a saline ultrasound dilution method. RESULTS: All failures of vascular access were due to AVF thrombosis; none were attributed to an inadequacy of the dialysis dose. AVF thrombosis occurred in nine cases; a rate of 0.043 AVF thrombosis per patient-year at risk. A receiver operating characteristic curve, evaluating the diagnostic accuracy of baseline vascular access blood flow rate values in predicting AVF failure, showed an under-the-curve area of 0.82+/-0.05 SD (P = 0.01). The value of vascular access blood flow rate, identified as a predictor of AVF failure, was <700 ml/min with an 88.9% sensitivity and 68.6% specificity. When subdividing the population of AVFs into two groups according to the baseline vascular access blood flow rates, two out of the nine thromboses occurred among the AVFs that had baseline blood flow rates >700 ml/min (n = 31), whereas seven occurred among the AVFs that had baseline blood flow rates <700 ml/min (n = 21). The 4 year cumulative actuarial survival was 74.36 and 20.80%, respectively (log-rank test, P = 0.04). The 24 AVFs that remained patent at the end of the 4 years maintained a median blood flow rate > or =900 ml/min at all time points studied. Worth noting is that, five of them (20.8%) remained patent throughout the study with a blood flow rate consistently < or =500 ml/min. CONCLUSIONS: This study shows a very low rate of AVF thrombosis per patient-year at risk and a high actuarial survival of autogenous RC wrist AVFs, particularly of those having a blood flow rate >700 ml/min. Thus, a vascular access blood flow rate <700 ml/min appears to be a reliable cut-off point at which to start a closer monitoring of this parameter-which may lead to further investigations and possibly interventions relevant to the function of the AVFs.     

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.     

球囊扩张成形术处理透析用动静脉内瘘狭窄性病变及短中期结果

目的:探讨球囊扩张成形技术在治疗血液透析用动静脉内瘘(AVF)狭窄的临床效果。方法:回顾性分析2014年5月—2015年12月间采用球囊扩张成形技术治疗的31例血液透析用AVF狭窄性病变患者的临床资料。结果:31例患者中,男18例,女13例;桡动脉-头静脉内瘘27例,桡动脉-贵要静脉内瘘2例,尺动脉-贵要静脉内瘘2例;均接受球囊扩张技术治疗。28例(90.3%)获得技术上的成功,围手术期无患者死亡。1例患者术后出现动脉穿刺处假性动脉瘤,1例患者术后出现AVF血栓形成,1例患者出现前臂皮下血肿,其他所有患者AVF恢复通畅并能够以正常流量进行血液透析治疗。术后随访3~12个月,3、6、12个月初次通畅率分别为92.9%,75.0%,50.0%。结论:球囊扩张成形术处理AVF狭窄性病变微创、安全,是AVF狭窄性病变的合理治疗方法,但其中长期疗效仍有待于进一步改善。     

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。     

Hemodialysis arteriovenous access: detection of stenosis and response to treatment by vascular access blood flow

BACKGROUND: Hemodialysis access to the circulation is best provided by native and synthetic arteriovenous fistulae (AVF and AVG). Thromboses caused by venous outflow stenoses prevent the long-term use of AV access. This pilot study was performed to evaluate the ability of ultrasound dilution-derived access blood flows to detect AV access stenosis and to evaluate the response to treatment. METHODS: This pilot study was a single-center, prospective observational intervention trial. The monitoring technique used was ultrasound dilution access blood flow measurements performed monthly and after any intervention. Screening criteria for interventions were decrements in access flow of 20% when the flow value fell under 1000 mL/min or absolute flow of <600 mL/min. The primary intervention when flow criteria were met was biplanar venography of the access with percutaneous transluminal angioplasty (PTA) of detected stenoses. Stenoses unresponsive to PTA were sent for surgical revision. Access thrombosis was considered a study ending event. RESULTS: Baseline access flow at study entry for AVF was 919 and 1237 mL/min for AVG. Sequential measurement of AV access flow detected AV access stenosis. PTA and surgical revision significantly restored AV access flow back toward the baseline flow measurement. Failure to restore access flow by at least 20% following intervention occurred in 14% of AVF and 21% of AVG PTA attempts. Transluminal angioplasty, once successfully performed, was required at a mean of 5.8-month intervals in order to maintain AVG flow. In contrast, AVF flow was restored for a much longer period of time following angioplasty (11.4 month follow-up at the time of study end). Compared with historic controls, which used venous dialysis pressure as the primary monitoring technique, the overall (AVF-AVG) thrombosis rates improved from 25 to 16% per patient year, and AVF thrombosis rates improved from 16 to 7% per patient year. When flow was not successfully restored, thrombosis ensued. Eight of 10 thrombosis episodes were predicted based on inability to improve access flow either as a result of stenosis treatment failure or unsuccessful referral for treatment. CONCLUSION: Sequential measurement of AV access flow is an acceptable means of both monitoring for the development of access stenoses and assessing response to therapy. PTAs of AVF are more durable than PTAs of AV grafts.     

Access blood flow as a predictor of early failures of native arteriovenous fistulas in hemodialysis patients.

Blood flow imaging using color doppler has proven effective in predicting graft failures in hemodialysis patients, but its effect on native arteriovenous fistulas (AVF) is not well known. This study was performed to investigate whether measurements of the access blood flow can be used as predictors of an early failure of a native AVF in hemodialysis patients. Fifty-three consecutive patients who received native AVF operations were included in this study. Access blood flow was measured at 1 week after operations, and AVF function was followed for 4 months. During the follow-up, access failures developed in 10 patients at 9.8 +/- 3.5 weeks. AVF blood flow was significantly lower in the failure group (n = 10) than in the patent group (n = 43) (450 +/- 214 vs. 814 +/- 348 ml/min, p = 0.003). The incidence of access failures was higher in the patients with a flow <350 ml/min (n = 9) compared to the patients with a flow >350 ml/min (n = 44) (55.5 vs. 11.3%, p = 0.008). The diameters of veins were significantly smaller in the failure group than in the patent group (3.5 +/- 0.5 vs. 4.1 +/- 0.7 mm, p = 0.018). The incidence of diabetes mellitus was higher in the failure group than in the patent group (90 vs. 51%, p = 0.025). However, age, sex, duration from an operation to first cannulation, and different AVF sites did not make a significant difference between the two groups. Our data suggest that access blood flow measurements using color doppler ultrasound during early postoperative periods are useful parameters in predicting an early failure of a native AVF in hemodialysis patients.     

Color doppler ultrasonography imaging to guide transluminal angioplasty of venous stenosis

BACKGROUND: The objective of access surveillance is the early recognition of dysfunction in order to be able to correct the stenosis by angioplasty or surgery before access thrombosis occurs. The advent of color Doppler imaging has enabled studies of color Doppler ultrasonography (CDU) for the guidance of percutaneous transluminal angioplasty (PTA). The aim of the present study was to investigate whether color Doppler imaging alone can be safely and effectively used to diagnose vascular graft access stenoses and guide subsequent PTA. METHODS: Using the ultrasound velocity dilution method, we measured access blood flow (Qa) during the first hour of hemodialysis every month in patients with grafts as vascular access. When the decrease in Qa from the baseline value was 40% or more, CDU was performed and immediately followed by PTA in the presence of a stenosis of more than 50%. The Qa was then measured during the first dialysis after PTA and one month later. Repeated-measure analysis of variance was applied to evaluate the early and late (after one month) effect of PTA. RESULTS: Twelve PTAs were performed under CDU guidance in nine patients and led to the elimination of the stenosis or its reduction (two cases). The mean Qa was 809 +/- 263 mL/min at baseline, 468 +/- 153 before PTA, and 820 +/- 281 after PTA. The difference between the pre-PTA and post-PTA values was highly significant (P < 0.001), and the mean value after PTA was not different from baseline (P = 0.672). There were no relevant complications directly related to the procedure. CONCLUSIONS: The CDU procedure is effective for the diagnosis of vascular access stenosis and as a guide during the PTA procedure. It could improve stenosis screening by avoiding the risks of exposure to ionizing radiation and of adverse reactions to contrast media.     

Drug-coated balloon angioplasty for dialysis access fistula stenosis

Maintaining vascular access patency represents a tremendous challenge in hemodialysis patients. Although “native” arteriovenous fistula (AVF) is currently recommended as primary vascular access, neointimal hyperplasia stenoses frequently develop, with a risk for AVF thrombosis and vascular access loss. For years, first-line treatment of AVFs stenoses has been percutaneous transluminal angioplasty, generally with high-pressure or cutting uncoated balloons. However, restenosis and reintervention rates remain incredibly high and occur, according to recent studies, in up to 60% and 70% of patients at 6 and 12 months, respectively. Drug-coated balloons delivering paclitaxel at the angioplasty site have proved their superiority in the treatment of coronary and peripheral arterial stenoses. Paclitaxel reduces neointimal hyperplasia and drug-coated balloons, therefore, it represents an attractive option for AVF stenoses. Because data are scarce, the aim of this paper was to review the concepts and current results of drug-coated balloons in AVF stenosis management.     

Prospective validation of an algorithm to maximize native arteriovenous fistulae for chronic hemodialysis access

OBJECTIVE: The purpose of this study was to evaluate an algorithm to maximize native arteriovenous fistulae (AVF) for hemodialysis access. METHODS: The prospective study design was set in an academic, tertiary care medical center. The study subjects were adults referred for permanent, upper extremity hemodialysis access between April 1999 and May 2001. Intervention included Doppler arterial pressures/waveforms and duplex imaging of the basilic, cephalic, and central veins. The optimal configuration for an AVF was determined (criteria: vein >3 mm, no arterial inflow stenosis, no venous outflow stenosis) on the basis of the noninvasive studies, and unilateral arteriography/venography was performed to confirm the choice. Permanent hemodialysis access was created on the basis of the imaging studies, and remedial imaging/intervention was performed if the AVF failed to mature. Outcome measures included impact of the noninvasive/invasive imaging, perioperative morbidity/mortality, incidence of successful AVF, time to cannulation, and predictors of AVF failure with multivariate analysis. RESULTS: A total of 139 new access procedures was performed in 131 patients (age, 53 +/- 16 years; male, 51%; white, 60%; diabetic, 49%; actively undergoing dialysis, 50%; prior permanent access, 26%). The noninvasive imaging showed that 83% of the patients were candidates for AVF, with a mean of 2.7 +/- 2.1 possible configurations. Invasive imaging was abnormal in 38% (forearm arterial disease > central vein stenosis > inflow stenosis) and impacted the operative plan in 19%. AVF were performed in 90% of the cases (brachiobasilic > brachiocephalic > radiocephalic > radiobasilic), with prosthetic AVF performed primarily because of inadequate veins. Among the patients who underwent AVF, the 30-day mortality rate was 1%, the complication rate was 20% (wound, 10%; hand ischemia, 8%), and 24% needed a remedial procedure. The AVF matured sufficiently for cannulation in 84% of those with sufficient follow-up and was suitable for cannulation by 3.4 +/- 1.8 months. On the basis of an intention to treat approach, an AVF sufficient for cannulation developed in 71% of the 139 cases referred for access. The multivariate analysis predicted that female gender (odds ratio, 9.7; 95% CI, 2.2 to 43.5) and the radiocephalic configuration (odds ratio, 4.6; 95% CI, 1.1 to 18.6) were both independent predictors of failure of the fistula to mature. CONCLUSION: With the aggressive algorithm, the construction of native AVF is possible in the overwhelming majority of patients presenting for new hemodialysis access.