Treatment of "swing point stenoses" in hemodialysis arteriovenous fistulae

AIM: This is a retrospective study of percutaneous transluminal balloon angioplasty (PTA) efficacy for treatment of surgical vein mobilization site ("swing point") stenoses in hemodialysis arteriovenous fistulae (AVF) that fail to mature or are poorly functioning. METHOD: Between February 1, 1999, and February 28, 2001, 65 non-maturing or poorly functioning AVF were studied in 63 consecutive hemodialysis patients (30 male, 33 female, aged 26-92 years). All AVF underwent contrast angiography to study the inflow artery, AVF, outflow and central veins. PTA of stenotic sites was performed to initiate or restore AVF function. RESULTS: Seventy-eight venous and 2 arterial stenoses were found and treated with PTA in the 65 AVF. All PTA were technically successful. A total of 55 stenoses were identified in the vein at the site of surgical mobilization ("swing point"). Additionally, 19 cephalic and 4 central venous stenoses were found. During the study, 13 AVF underwent repeat PTA at the "swing point". Of the 65 AVF treated, 50 were being successfully used as an access site, 4 AVF were lost during follow-up (34-688 days; mean: 258 days) and 8 patients died within the study period. The duration of functional patency of the treated AVF was 39-660 days (mean: 280 days). CONCLUSION: Non-maturing or poorly functioning AVF frequently have stenoses in the outflow vein at the original site of surgical vein mobilization. These "swing point stenoses" are amenable to PTA, which is a safe and effective treatment for prolonging AVF patency and function.     

Obesity as a predictor of vascular access outcomes: analysis of the USRDS DMMS Wave II study

Arteriovenous fistulae (AVF) are widely regarded as the preferred vascular access in hemodialysis patients due to their primary patency and patient survival benefits. While the obesity paradox has been associated with improved cardiovascular morbidity and all-cause mortality in dialysis patients, its long-term vascular access outcomes are less clear. Recent literature has suggested that obese patients may have increased early and late fistula failure. The purpose of this study was to explore the relationships between obesity and vascular access outcomes. We performed a retrospective cohort analysis using the USRDS DMMS Wave 2 data set. All incident dialysis patients as of January 1, 1996, over the age of 18, receiving only hemodialysis as mode of renal replacement therapy were eligible for inclusion. Among other variables, data collected for the DMMS Wave 2 included: type and location of vascular access, AVF maturity, vascular access revision, and failure. Logistic regression analyses were used to examine the relationships between obesity and vascular access outcomes, adjusting for important covariates. In all, 1486 hemodialysis patients were included. Using body mass index (BMI) <30 kg/m(2) as reference, obesity did not emerge as a factor in predicting vascular access revisions or failures. An increased risk of AVF failure to mature was found only in the highest BMI quartile (>or=35 kg/m(2)) (aOR 3.66 [95% CI 1.27-10.55], p = 0.017). Peripheral vascular disease was independently associated with an increased risk of AVF failure (aOR 2.78 [95% CI 1.01-7.63], p = 0.047) and arteriovenous graft (AVG) failure (aOR 1.65 [95% CI 1.03-2.64], p = 0.036). Obesity was not associated with increased AVF or AVG revision rates or failure and only associated with poorer AVF maturity at highest BMI quartile. We conclude that obesity should not preclude placement of AVF as vascular access of choice, except in the very obese where assessment should be individually based.     

Can the National Kidney Foundation guidelines for first-time arteriovenous fistula creation be met in underserved end-stage renal disease patients?

The aims of this study were to determine whether National Kidney Foundation (NKF) guidelines for native arteriovenous fistula (AVF) creation (at least 50% of all new end-stage renal disease [ESRD] patients and 40% of prevalent hemodialysis patients) could be met in an underserved population who presented in late stages of ESRD. We also sought to determine 1-year AVF patency rates and factors associated with early thrombosis. One hundred seventy-six patients underwent hemodialysis access surgery during the period 2003-2005 with a mean age of 51 years. Sixty-two percent were male, and 48% had diabetes mellitus. Ultrasound vein mapping was performed in only 37%. Temporary central venous access was necessary in 109 patients (62%) due to late presentation. Of the 160 patients who were first-time access, 137 (86%) received a native AVF and 23 (14%) had an arteriovenous graft. There was a higher rate of AVF creation in males (91% vs. 75% for females, p = 0.005). The 1-year primary patency was 90%. There were no differences in early thrombosis or 1-year patency rates with respect to gender, age, ethnicity, insurance status, presence of temporary access, or use of preoperative vein mapping. In an underserved population, NKF guidelines for native AVF for first-time access can be superseded with an excellent 1-year patency, despite late presentation.     

Body mass index and cardiovascular risk factors and biomarkers in hemodialysis patients

BACKGROUND: Being overweight and obesity are associated with improved survival in hemodialysis (HD) patients, based on mechanisms that are presently uncertain. We compared traditional and uremia-related cardiovascular risk factors in HD patients stratified according to their body mass index (BMI). METHODS: One hundred sixteen HD patients were stratified into 4 groups according to the BMI: underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9) and obese (> or =30). Blood samples were obtained before the HD session to measure serum albumin, high-sensitivity C-reactive protein, fibrinogen, ferritin, total cholesterol, LDL cholesterol, HDL cholesterol, apolipoprotein A-I and apolipoprotein B-100, apolipoprotein B (apoB) to apolipoprotein A (apoA) ratio and Lp(a) lipoprotein. RESULTS: There were 3 underweight (excluded from the analysis), 58 normal weight, 35 overweight and 20 obese patients. Their mean age was 62.1 +/- 14.1 years. There were 68 men and 45 women. Mean dialytic age was 5.32 +/- 3.2 years. The mean BMI of the study population was 25.2 +/- 4.1. The prevalence of smoking habit was similar in the 3 groups (17.2%, 8.5% and 25%, respectively; p=0.28). The prevalence of hypertension was higher in overweight (77.1%) and obese (65%) patients than in leaner counterparts (53.4%), although the difference was not significant. Conversely, diabetes prevalence was significantly higher in overweight and obese patients (22.8% and 30%, respectively) than in normal weight patients (6.9%; p=0.02). The serum levels of total cholesterol, HDL cholesterol, LDL cholesterol, Lp(a) lipoprotein, apolipoprotein A-I, apolipoprotein B-100, and apoA/apoB ratio were similar in the 3 BMI groups. Triglycerides levels were significantly higher in obese (221.2 +/- 132.7 mg/dL) and overweight (230.5 +/- 119.3 mg/dL) patients than in those of normal weight (154.6 +/- 78.8 mg/dL; p=0.02). Most of the uremia-related cardiovascular risk factors (anemia, hyperparathyroidism, chronic inflammation) were comparable among BMI categories as well as the levels of C-reactive protein, fibrinogen and ferritin. CONCLUSION: The present study suggests that almost all traditional and uremia-related cardiovascular risk factors do not differ significantly among different categories of BMI in hemodialysis patients.     

Discordant utility of ideal body weight and body mass index as predictors of mortality in lung transplant recipients.

BACKGROUND: An upper limit of 130% predicted ideal body weight (PIBW) has been promulgated for assessing lung transplant (LTx) candidacy, but no data in the lung transplant population support this value. A prior study used body mass index (BMI) to suggest greater mortality risk in obese allograft recipients, but the number of studied patients was small. METHODS: Pre-operative PIBW percentage and BMI were obtained for all first-time, adult LTx recipients at our institution (n = 283). We compared survival data at 90 days and as of July 31, 2002, using multivariable regression and Cox modeling. RESULTS: There were 46 obese (BMI > or = 30) patients and 72 patients >130% PIBW, including 43 patients previously thought to fall within a normal PIBW range who were reclassified as overweight for this analysis. Cox modeling revealed no significant impact of PIBW (>130% or continuous) or BMI (>30 kg/m(2) or continuous) on overall survival. Predicted ideal body weight also had no influence on 90-day mortality. When we tested PIBW in the group previously deemed of acceptable weight, we likewise found no association with mortality at 90 days or overall. For BMI only, 90-day odds ratios for death were significantly greater for obese (BMI > or = 30; odds ratio, 3.16; 95% confidence interval, 1.05-9.48) patients than for normal-weight patients. CONCLUSION: Indices of pre-operative obesity did not predict long-term outcome in this large cohort of LTx recipients. The data suggest that BMI stratification may identify a group of patients at risk for increased short-term mortality, whereas PIBW is not a significant outcome predictor.     

长期维持性血液透析患者并发的肺动脉高压

目的 研究长期维持性血液透析(MHD)患者肺动脉高压(PHT)的特征及相关因素.方法 参照2010年美国心脏超声协会右心检测指南,肺动脉收缩压(PASP)＞35 mm Hg诊为PHT.超声心动图和脉搏波传导速度(baPWV)于透析后次日集中检测.自体动静脉内瘘(AVF)流量采用超声稀释法检测.收集及评估患者的透析相关信息,取血检测血常规、钙、磷、甲状旁腺激素(iPTH)、肝肾功能等指标.结果 我院透析中心进行MHD 6个月以上,采用自体AVF并除外其他疾病引起并发PHT者,共111例,其中男性45例,女性66例,平均年龄( 57.32±12.49)岁,平均透析龄为(70.51±44.98)个月.28例诊为PHT,占25.23％,平均PASP为(45.68±10.83) mm Hg.PHT组的左室舒张功能不全明显较非PHT组常见(53.60％比6.02％,P＜0.01).PHT组左室射血分数(EF)值(62.06％±14.90％比69.72％±8.60％)、左室内径缩短分数(36.46％±10.04％比40.20％±7.86％)均低于非PHT组(均P＜0.01).EF＜50％者在PHT组和非PHT组分别占21.43％和3.61％.但PHT组和非PHT组在年龄、性别、透析龄、身高、体质量指数(BMl)、透析间期平均每日体质量增长、透析前血压、血红蛋白、血白蛋白、前白蛋白、血钙、血磷、iPTH、标准化蛋白分解率(nPCR)、Kt/V、baPWV以及AVF流量等差异均无统计学意义.结论 PHT是维持性血液透析常见的并发症,其发生与左室收缩和舒张功能下降密切相关;与钙磷代谢、AVF流量、血红蛋白、透析充分性及营养状态等无明显相关性.     

Ultrasonographic maturation of native arteriovenous fistulae: a follow-up study

BACKGROUND/AIMS: Ideal time needed for arteriovenous fistula (AVF) maturation is still controversial. In this study, we aimed to investigate the natural course of AVF maturation and also investigated the factors affecting AVF maturation. METHODS: We studied 31 (21M/10F, mean age 55.8 +/- 16.2) chronic renal failure patients. We evaluated the patients with color Doppler ultrasound examination before the fistula operation, at the first day, and at the first, second, third, and sixth months. Radial artery (RA) diameter, flow velocity, flow, resistance index, fistula vein diameter, flow velocity, and flow were measured. RESULTS: Patency rates at the first post-operative day and the sixth month were 87.1% and 67.1%, respectively. Cephalic vein flow was 451.2 +/- 248.6 mL/min at the first month and 528.6 +/- 316.5 mL/min at the sixth month. Baseline RA diameter was lower in failing fistulas than that of patent fistulas. Failing fistulas were more common in women. CONCLUSION: Blood flow was enough for hemodialysis at the end of the first month. However, fistula maturation had continued until the end of the study; women and patients with low RA diameter are particularly prone to fistula failure. Therefore, especially in these patients, AVF must be created at least three or four months before the predicted hemodialysis initiation time.     

Impact of ultrasonographic vascular mapping on constructing autogenous arteriovenous fistulas for permanent hemodialysis access?

PURPOSE: We used high resolution ultrasonography to identify usable veins and arteries in the forearm for creation of autogenous arteriovenous fistulas (AVF) for permanent hemodialysis access. The effect of preoperative vascular mapping followed by intraoperative controls on the outcome of AVF should be reported. METHODS: study subjects were adults referred for primary permanent hemodialysis access between January 2001 and November 2002. In all patients sonographic assessment was performed before surgical evaluation. A feeding artery was considered adequate if the diameter was more than 1.5 mm, the vein more than 2.0 mm. All AVF were controlled by intraoperative sonographic measurements of PSV and diameter of the fistula-vein. RESULTS: AVF were placed in 94.1% of all patients. The early failure rate of AVF was 6.3%. Primary patency rate of AVF after 24 hours: 93.7%, after 30 days: 91.4%, after 3 months: 86.9%, preliminary patency rate after 1 year: 70.1%. No unsuccessful surgical explorations were performed. 85.5 % of AVF were constructed as forearm fistulas. Suboptimal vessels (artery < 2.0 mm, vein < 3.0 mm) were used in 31.3% of patients. Patency rates did not differ in this subgroup. In 2 patients synthetic grafts were placed because of non-maturation of AVF. In 15 patients the AVF had to be cannulated by experts for 3 to 6 months. 50.0% of all AVF were constructed in diabetic patients. Patency rates were equal to that of non-diabetic patients. No patient suffered on signs of steal-syndrome. CONCLUSION: the assessment of forearm vessels by high resolution sonographic vascular mapping helps to find the optimal location for constructing an arteriovenous wrist fistula in almost all patients needing a permanent hemodialysis access. The aggressive approach to the creation of autogenous fistulas could be realized without unsuccessful surgical explorations and with a minimal early failure rate, a high maturation rate including patients with diabetes mellitus and no signs of steal-syndrome     

Conversion of tunneled hemodialysis catheter-consigned patients to arteriovenous fistula

OBJECTIVE: Despite their high incidence of complications, costs, morbidity, and mortality, nearly 27% of the chronic hemodialysis (HD) patients are receiving treatment via a tunneled hemodialysis catheter (TDC). METHODS: In this prospective analysis, an interventional nephrology team employed an organized program consisting of vascular access (VA) education and vascular mapping (VM) to TDC-consigned patients. A full range of surgical approaches for arteriovenous fistula (AVF) creation, including vein transpositions, was exercised. Physical examination was performed every 1 to 2 weeks after surgery to assess the development of the AVF. Fistulas that failed to develop adequately to support HD (early failure) underwent salvage [percutaneous transluminal angioplasty (PTA), accessory vein obliteration (AVL)] procedures. RESULTS: One hundred twenty-one TDC-consigned patients received VA education. Eighty-six (71%) agreed to undergo VM. Two groups were identified. Group I (N= 66; using TDC for 7.2 +/- 1.8 SD months) had never had an arteriovenous access; group II (N= 20; using TDC for 12.3 +/- 4.0 months) had a history of one or more previously failed arteriovenous accesses. Upon VM, 64/66 (97%) in group I and 18/20 (90%) in group II were found to have adequate veins for AVF creation. Seven patients (11%) in group I and 3 (17%) in group II refused surgery. In group I, 57 (89%) received an arteriovenous access (radiocephalic AVF = 15, brachiocephalic AVF = 35, transposed brachiobasilic AVF = 3, brachiobasilic AVG = 4). In group II, 15 (83%) received a transposed AVF (radiobasilic = 2, brachiobasilic = 13). Sixteen fistulas (30%) in group I and 8 (53%) in group II had early failure. All except for one fistula in each group were salvaged using PTA and/or AVL. All 70 accesses (AVF = 66, AVG = 4) remain functional, with a mean follow-up of 8.5 +/- 3.6 months. CONCLUSION: These results demonstrate that an organized approach based upon a comprehensive program utilizing VA counseling, VM, application of full range of surgical techniques, and salvage procedures can be very successful in providing optimum vascular access to the catheter-dependent patient.     

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.     

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.     

Axillary artery to contralateral axillary vein graft fistula in chronic hemodialysis patients

BACKGROUND: Vascular access failure is a severe and common complication for hemodialysis patients. The possible vascular access sites are limited in dialysis patients. Axillary artery to contralateral axillary vein arteriovenous fistula (AVF) is one of the possibilities. However, the clinical outcome of this procedure is still un-defined. OBJECT: The purpose of this study is to review the clinical outcome of axillary artery to contralateral axillary vein AVF as a hemodialysis vascular access. PATIENTS AND METHODS: We retrospectively reviewed native or graft arteriovenous fistula records for chronic hemodialysis patients at Chang Gung Memorial Hospital in Kaohsiung, Taiwan, from January 1986 to March 2001. Records were reviewed for all chronic hemodialysis patients, with more than 2000 individuals receiving more than 10,000 fistulas. Eight patients received axillary artery to contralateral axillary vein AVF. RESULTS: The mean age for these patients was 61.7 +/- 16.3 year-old at time of surgery. All patients had received multiple native or graft arteriovenous fistula creation. The 2-year and 4-year AVF graft survival is 87.5% and 43.8% respectively. One patients developed brachial plexopathy after operation. Another patient had venous hypertension distal to the AVF site. Both patients were managed conservatively. There is no AVF-related mortality in these patients. CONCLUSION: We conclude that axillary artery to contralateral axillary vein graft fistula may be a feasible alternative choice for chronic hemodialysis access.     

Arteriovenous fistula reconstruction in patients with kidney allograft failure

Abstract: Background:  Kidney recipients with failing allograft function face the vascular access problem again before returning to hemodialysis. An autologous arteriovenous fistula (AVF), according to the recent Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines, is the optimal vascular access and the use of prosthetic grafts and catheters should be limited. The objective of this study was to assess the feasibility of AVF reconstruction in patients reentering hemodialysis after kidney allograft failure.
Materials and methods:  Two hundred and forty-one transplant recipients reentered hemodialysis between 1990 and 2005. Before kidney transplantation, 221 patients had a functioning AVF on the forearm. Fistula reconstruction was attempted in 112 (51%) patients because of AVF thrombosis. Three strategies were applied according to forearm vein patency: a new radial-cephalic fistula, a radial-perforating vein fistula, or a radial-basilic forearm transposition was created.
Results:  Forearm AVFs were successfully reconstructed in 85 of the 112 patients (73%). The primary patency of the reconstructed AVFs was 57.6% and 44% at 12 and 24 months. Secondary patency was 64.9% and 54.9% at 12 and 24 months, respectively.
Conclusions:  The reconstruction of an old, thrombosed AVF is possible in kidney recipients returning to dialysis, even if the time from thrombosis to fistula repair is a few years.     

Failure of arteriovenous fistula maturation: an unintended consequence of exceeding dialysis outcome quality Initiative guidelines for hemodialysis access

PURPOSE: The Dialysis Outcome Quality Initiative (DOQI) guidelines recommend that arteriovenous fistulas (AVF) be constructed in at least 50% of hemodialysis access procedures. Preoperative duplex ultrasound (US) scanning and venography may increase options for AVF with identification of veins that are not clinically evident. However, maturation of autogenous fistulas created on the basis of findings at duplex US scanning and venography has not been carefully examined. METHODS: From January 1999 to July 2002, 256 new hemodialysis access procedures were performed in 202 patients in an academic tertiary care center. If physical examination failed to disclose adequate vessels for hemodialysis access, patients underwent duplex US scanning mapping. Venography was performed when no usable vein or only a basilic vein was identified at duplex US scanning. Functional maturation rate and mean maturation time (time from fistula creation to initiation of hemodialysis) were determined. This experience was compared with that in a group of 128 patients in whom 148 hemodialysis access fistulas were created before we implemented liberal use of preoperative duplex US scanning and venography (January 1997-December 1998). RESULTS: From January 1999 to July 2002, preoperative duplex US scanning was performed in 68% of patients, and venography in 32% of patients. Autogenous fistula creation rate increased from 61% to 73% in all patients with hemodialysis access fistulas (P =.15) and from 66% to 83% in patients undergoing a first access procedure (P <.05). The use of basilic vein transposition also increased, from 3% in the earlier period to 13% in the later period (P <.05). Mean maturation time for arteriovenous fistulas was 70 days. Functional maturation rate decreased from 73% to 57% (P <.05) after implementation of preoperative imaging and more aggressive vein use. CONCLUSION: Implementation of preoperative duplex US scanning and venography as a component of a more aggressive protocol to create native fistulas was pivotal in exceeding DOQI guidelines for hemodialysis access. However, this approach resulted in the unintended sequela of decreased fistula maturation rate. Our experience suggests that improved selection criteria based on findings at preoperative imaging are needed to further refine and optimize arteriovenous access surgery.     

Prospective evaluation of factors associated with early failure of arteriovenous fistulae in hemodialysis patients

Recent guidelines have recommended performing native arteriovenous fistulae (AVF) in hemodialysis patients rather than synthetic grafts whenever possible. However, early failure of AVF may reach up to 50%. The purpose of this study was to assess the factors associated with early failure of such procedures in hemodialysis patients. A prospective study was performed on all patients with end-stage renal disease who had an AVF between June 2003 and March 2005. Data including patient characteristics and the type of AVF were recorded. The internal diameter of the vein and artery and intraoperative blood flow were measured. Patients were followed up for 3 months. One hundred twenty-six AVF were included in this study. Early failure was in 14 (9%) patients. The internal diameter of the vein and artery and intraoperative blood flow were significantly lower in the failure group than in the patent group. The failure rate was not significantly related to other parameters. Our data showed that intraoperative blood flow is a reliable parameter that determines the early failure of an AVF. Careful selection of the vein and the artery may reduce the rate of failure.     

The Clinical Utility of Doppler Ultrasound Prior to Arteriovenous Fistula Creation

Arteriovenous fistula (AVF) is the preferred access for long-term hemodialysis, with superior long-term patency rates; however, early failure rates are significant. Recent evidence has brought into question the preferred site of AVF creation in many patient groups. A preoperative test that could reliably predict the outcome of a proposed AVF would be of great benefit. Doppler ultrasound has been the most extensively studied and widely used test to guide access creation. Accurate and validated measurements of internal vessel diameter, both arterial and venous, and blood flow in the upper extremity are obtainable by Doppler ultrasound. Studies evaluating the utility of Doppler ultrasound prior to AVF creation suggest that vessel size and blood flow are predictive of AVF outcome. An AVF created using a cephalic vein and/or radial artery smaller than 1.5–2.0 mm is likely to fail; such preoperative data may indicate that an upper arm AVF should be the primary access attempted. Further prospective studies are needed to evaluate the utility of Doppler ultrasound.     

Secondary arteriovenous fistulas: converting prosthetic AV grafts to autogenous dialysis access

As existing arteriovenous grafts (AVGs) fail, the National Kidney Foundation KDOQI Guidelines and the AV Fistula First Breakthrough Initiative ("Fistula First") project recommend that each patient be re-evaluated for conversion to an arteriovenous fistula (AVF). AVFs created following failure of an AVG have been termed secondary fistulas (SAVF). We review our experience and outcomes converting AVGs to SAVFs, utilizing the mature outflow vein of the AVG when possible, otherwise creating a new AVF at a remote site. We reviewed two groups of consecutive patients undergoing operations for vascular access at different centers. Group 1 had a SAVF protocol in place during the study period with specific criteria for timing SAVF construction. Patients from group 2 were referred for evaluation by nephrologists or dialysis nurses as access problems were recognized, without a formal protocol in place. All patients had preoperative ultrasound or contrast imaging in addition to physical examination. Indications for creating a SAVF were AVG thrombosis, dysfunction, erosion, bleeding, or steal syndrome involving the existing AVG. The simple presence of a functional AVG without evidence of dysfunction was not an indication for conversion to a SAVF. SAVFs were classified according to location and the potential for utilizing the existing mature AVG outflow vein. Group 1: 40 consecutive patients, age 26-78 (mean = 62), 42% were female; 55% were diabetic. These patients had 1-22 previous access operations (mean = 3). 92.5% underwent SAVF surgery prior to loss of the AVG, minimizing catheter use. Cumulative patency was 92.5% at 1 year and 87.5% at 2 years. Group 2: 102 consecutive patients, age 24-87 (mean = 55), 52% were female; 50% were diabetic. These patients had 1-50 previous access operations (mean = 3). Only 19.3% were referred for SAVF surgery prior to loss of the AVG or outflow vein. Cumulative patency was 94.4% at 1 year and 91.6% at 2 years. Failure, dysfunction, or complications of AVGs may be resolved by conversion to a SAVF. Further, the limited lifespan of AVGs and the superiority of AVFs dictates that a plan be in place to transition the AVG patient to an AVF. Most, if not all, hemodialysis patients whose access is an AVG will have one or more anatomic sites and vessels suitable for an autogenous SAVF. Vessel mapping is critical in the evaluation of failing AVGs and in preparation for a SAVF. Cumulative patency rates exceeded 90% at 12 months for SAVFs in both patient groups in this report. The need for catheters was dramatically less in the patient group with an established SAVF conversion plan.     

Vascular access outcomes as a predictor of development of chronic allograft nephropathy

INTRODUCTION: The vascular condition influences the outcomes of arteriovenous fistula (AVF) surgery. However, it has not been established how it influences the outcomes of renal transplantation and the development of chronic allograft nephropathy (CAN). The aim of this study was to define the relationship between AVF failure in the pretransplant period and the development of CAN. PATIENTS AND METHODS: In this study we included all patients who underwent AVF surgery and then first kidney allotransplantations from January 1, 1999 to December 31, 2002. Patients were divided into two groups according to the AVF surgery outcomes: group 1 (n = 45, mean age 50 +/- 13 years, male/female ratio 27/18) had no vascular access complications and were dialysed through a native AVF. Group 2 (n = 39, mean age 51 +/- 11 years, male/female ratio 17/22) had additional interventions due to AVF failure. We analyzed the incidence of CAN in both groups. RESULTS: During the follow-up period CAN was observed in five patients in group 1 and 11 patients in group 2 (11,1% vs 28,2%, P < .05). There was a statistically significant relationship between CAN and acute rejection episodes (P < .005) and diabetes mellitus (P < .05). CONCLUSION: Failures of arteriovenous fistulas in hemodialysis patients were associated with an increased incidence of CAN in the posttransplant period.     

Color Doppler US Evaluation of Feeding Artery after Balloon Angioplasty of the Drainage Vein in Dysfunctional Hemodialysis AVF

Purpose.?The aim of this study was to investigate flow rate and resistive index (RI) parameters of the feeding artery after balloon angioplasty of the drainage vein in dysfunctional hemodialysis arteriovenous fistula (AVF) due to venous stenosis/thrombosis.?Methods.?A cohort of 10 patients with native dysfunctional hemodialysis AVF was evaluated prospectively. Three of the 10 patients had a thrombosed drainage vein, and the remaining seven patients had a stenotic drainage vein. Flow rate and RI of the feeding artery of AVF were calculated by Color Doppler ultrasound (CDU) before and after balloon angioplasty and in the follow-up period. The flow rates and RI values before and after angioplasty and in the follow-up were compared.?Results.?Increased flow rate and decreased RI values were detected after balloon angioplasty in all patients. We detected restenosis or thrombosis of drainage vein in six of the patients in the follow-up period. Decreased flow rate and increased RI values compared with previous measurements were calculated in these patients.?Conclusions.?Increased flow rate and decreased RI in the feeding artery of native dysfunctional AVF were demonstrated in patients who underwent balloon angioplasty on the stenotic vein. If restenosis develops in the follow-up period, the previous high resistance flow pattern is observed again. Feeding artery flow parameters as calculated by CDU can be used as a simple indicator of possible drainage vein problems of native AVF.     

体重指数及年龄对人工关节置换术后下肢深静脉血栓形成的影响

目的探讨体重指数及年龄对人工关节置换术后下肢深静脉血栓形成(deepveinthrombosis,DVT)的影响。方法采用病例对照研究,分析2004年4月～2004年8月符合纳入条件行髋、膝人工关节置换术的95例患者的临床资料。其中男27例,女68例。年龄23～78岁,平均60岁。体重指数(bodymassindex,BMI)14.34～40.39kg/m2,平均25.88kg/m2。人工髋关节置换43例48髋,人工膝关节置换52例80膝。患者按WHOBMI标准分层,即:非肥胖BMI≤25.00kg/m2、超重BMI25.01～27.00kg/m2、肥胖BMI27.01～30.00kg/m2、病理性肥胖BMI>30.00kg/m2,以及按年龄分为≤40岁、41～60岁、61～70岁、>70岁4层,研究其与关节置换术后DVT的相关性。患者术前及术后7～10d均行低分子肝素抗凝预防术后DVT,并于术后7～10d采用彩色多普勒检查双下肢深静脉血流通畅情况及DVT发生率。结果术后45例患者发生DVT,发生率为47.4%,近端DVT发生率为3.2%。DVT组BMI为27.50±3.18kg/m2,高于无DVT组(24.42±4.51kg/m2),差异有统计学意义(P<0.05);分层后,BMI>25kg/m2的患者发生DVT的风险是BMI≤25kg/m2患者的2.24倍(P<0.05);BMI按WHO标准进行分层后,超重、肥胖及病理性肥胖的患者发生DVT的风险分别是非肥胖患者的7.04、4.80及9.60倍,差异均有统计学意义(P<0.05),肥胖患者发生DVT的风险比其他两层患者低,而病理性肥胖患者发生DVT的风险最高。DVT组年龄为65.24±6.98岁,高于无DVT组(54.84±15.11岁),差异有统计学意义(P<0.05)。41～60岁、61～70岁及>70岁组患者发生DVT的风险分别是年龄≤40岁患者的24.0、38.2及24.4倍,差异均有统计学意义(P<0.05)。结论肥胖(BMI>25kg/m2)及高龄(年龄>40岁)是影响人工关节置换术后DVT形成的高危因素,其中61～70岁的患者发生DVT的风险最高。肥胖、高龄患者行人工关节置换术时应予足够预防性抗凝治疗,术后严密观察双下肢情况,必要时行超声或静脉造影检查,防止发生致命性肺栓塞。