Arteriovenous Fistula Malfunction Research Articles

The influence of near-infrared therapy on arteriovenous fistula patency in haemodialysis patients: A multicentre, randomised, controlled clinical trial.

Arteriovenous fistula (AVF) is the preferred vascular access for patients undergoing haemodialysis (HD). AVF malfunction remains a major clinical problem and is a significant independent risk factor for death. Although far-infrared (FIR) therapy has been shown to reduce complications and improve the patency rate of AVFs in various studies, it has been cautiously recommended by the Kidney Disease Outcome Quality Initiative (KDOQI) guidelines for AVF care due to insufficient evidence. Therefore, it is necessary to identify more effective methods for preventing AVF dysfunction. Many in vitro studies and few clinical studies have examined the effects of near-infrared (NIR) therapy on the vasculature. This study will examine the effects of NIR therapy on AVF. A randomised, controlled, open-label, multicentre trial will compare the effect of NIR on AVF patency after 1 year of therapy with that of a control group of patients with existing AVF. One group of patients received NIR treatment above their AVFs, whereas the control group received regular care. The primary outcome is the primary fistula patency rate within 12 months. In addition, acute changes in inflammatory, vasodilatory and haemodynamic parameters after a single treatment in the first 40 participants will be examined. This study was registered in the Clinical Trials Registry (ChiCTR2300071305) at https://register.clinicaltrials.gov/. This study will explore the long-term and acute effects of NIR on AVFs. The study findings will provide information that can be used to develop new technical support for the prevention of AVF dysfunction in patients undergoing haemodialysis.

High Neutrophil-to-Lymphocyte and Platelet-to-Lymphocyte Ratios Are Associated with a Higher Risk of Hemodialysis Vascular Access Failure.

Our aim was to determine the predictive role of the preoperative neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in vascular access malfunctioning in patients who had undergone their first native arterio-venous fistula (AVF) for hemodialysis. Methods: This was a single-center retrospective observational study. All patients who underwent the procedure of the creation of a first native AVF for hemodialysis from January 2019 to December 2020 were considered eligible to be part of this study. Reinterventions for AVF malfunctioning were registered and the population was subdivided into two groups with respect to AVF malfunctioning. ROC curves were obtained to find the appropriate cut-off values for the NLR and PLR. A multivariate analysis was used to identify the independent predictors for an AVF malfunction. Kaplan–Meier curves were used to evaluate the AVF patency rates. A total of 178 patients were enrolled in the study, of them 70% (n = 121) were male. The mean age was 67.5 ± 12 years. Reinterventions for AVF malfunctioning were performed on 102 patients (57.3%). An NLR > 4.21 and a PLR > 208.8 was selected as the cut-off for AVF malfunctioning. The study population was divided into two groups depending on the NLR and PLR values of the individual. For the NLR < 4.21 group, the AVF patency rates were 90.7%, 85.3%, and 84% at the 3-, 6-, and 12-month follow-up, respectively, and 77.5%, 65.8%, and 39.3% at 3, 6, and 12 months for the NLR > 4.21 group, respectively (p < 0.0001). For the PLR < 208.8 group, the patency rates were 85.6%, 76.7%, and 67.7% at the 3-, 6-, and 12-month follow-up. For the PLR > 208.28 group, the patency rates were 80.8%, 71.2%, and 50.7% for the 3-, 6-, and 12-month follow-up, respectively (p = 0.014). The multivariate analysis highlighted that diabetes mellitus, the neutrophil count, the lymphocyte count, and the NLR were independent risk factors for an AVF failure. In our experience, the NLR and PLR are useful markers for the stratification of vascular access failure in hemodialysis patients. The inexpensive nature and ready availability of the values of these biomarkers are two points of strength for everyday clinical practice.

MO782: Evaluation of Acceleromet Reuse for Method of Measurement for Turbulent Blood Flow in Arteriovenous Fistulas in Haemodialysis Patients

Abstract BACKGROUND AND AIMS Haemodialysis (HD) is the primary treatment for end-stage renal disease. HD therapy requires access to the vascular system. This can be achieved through surgically constructing an arteriovenous fistula (AVF). Post-surgery up to 30% of patients experience dysfunction of the AVF, which may lead to a chronically damaged AVF and render the patient without HD treatment [1]. At present no satisfactory post-surgery monitoring of the AVF exist and, therefore, malfunction of the AVF is recognized too late at a time where no rescue is possible. The functionality of the AVF is normally assessed by auscultation of the murmurs produced by the blood flow. Narrowing of the AVF caused by thrombosis or stenosis causes changes in the blood flow, thus causing changes in the murmurs [2]. The changes in murmurs have not been widely studied but may be of importance to gain knowledge on AVF malfunction. This could be used in developing a method for monitoring the AVF post-surgery. METHOD Acoustic recordings was obtained from 21 patient post AVF-surgery at Aalborg University Hospital. Recordings were made with a Silicon Designs 1521 accelerometer encapsulated in a 3D printed box, attached to the skin using double adhesive tape 2–5 cm proximal to the AVF. A total of 11 patients were recorded twice resulting in a total of 32 recordings. Data were sampled at 5000Hz. All data processing and analysis were performed using MATLAB 2021b (MathWorks Inc.). Every recording was manually analysed and labelled with or without audible murmurs. Before processing every recording was split into segments of 3 sec length resulting in a total of 697 segments. Data was processed with a signal processing method [wavelet packet decomposition (Daubechies 4)] to analyse if the frequencies of the sounds differed between recordings with and without murmurs. Energy of the wavelet scales (Scale Energy) was calculated for each frequency band. The scale energy was then log-transformed using natural logarithm to make data normally distributed, and converted to decibel (dB). RESULTS A total of 654 segments contained murmurs and 43 segments did not contain murmurs. In all frequency bands, murmurs resulted in a significant change in energy level (P &amp;lt; 0.05). CONCLUSION This study shows AVF murmurs results in a significant change in acoustic energy across all frequency bands. This demonstrates that accelerometers can be used to quantify murmurs from AVFs post-surgery.

P1351MARKERS FOR AVF DYSFUNCTION; A RETROSPECTIVE ANALYSIS

Abstract Background and Aims The native Arterio venous fistula (AVF) is the recommended first choice for regular hemodialysis treatment. However, its patency is mainly limited due to stenosis and thrombosis, leading to insufficient dialysis, costly interventions, subsequent in-hospital care and follow ups. Primary aim: To find medical or laboratory markers associated with dysfunctional AVF. Method Retrospective analysis of radiologic examinations and medical records was made due to clinical suspicion of AVF dysfunction (cases) from two hospitals during 2006-2014. Comparison was made with data from 52 patients without complications (controls) with repeated blood sampling during the same period. Differences between groups were calculated with Mann- Whitney test and paired statistics with Wilcoxon U test before and after examination. Results Mean age in both groups was 65 years. In 153 patients 473 radiological examinations were performed due to clinical suspicion of dysfunction. Angiography and PTA were made when suitable according to guidelines. In 171 of these examinations no intervention was performed. Cases versus controls had lower access flow (599±442 vs 1140±523, p&amp;lt;0.001), blood pump speed (291±49 vs 313±34, p&amp;lt;0.001), PTH (31±39 vs 39±29 pmol/L, p=0,021), Ca-phosphate product (3.9±1.1 vs 4.2±1.0, p=0.025), C-reactive protein (17±25 vs 24±38, p=0.004) and, higher in regard to recirculation (5.1±11 vs 0.5±3.4, p&amp;lt;0.001), HbA1c (52±16 vs 47±17, p=0.027), dose of tinzaparin (14330±8000 vs 12743±5400U/week, p= 0.025), weekly dose of erythropoietin stimulating agent (ESA, 8900±7100 vs 4900±4600U/week, p&amp;lt;0,001), and higher weekly iron supplement dosing (60±61 vs 41±54mg/week, p&amp;lt;0.001). Alfa- and Beta-blockers against hypertension were more often used among cases. Conclusion The reason for AVF problems in cases showed limited disturbances in Ca-phosphate hemostasis and inflammation. Instead, it seems that higher dosing of ESA and LMWH (as indicator of clotting) are factors that could be associated with development of AVF malfunction.

Assessment of brachial artery mechanics using velocity vector imaging does not predict arteriovenous fistula failure; a feasibility study

Strain measurements by US have been suggested as a method of assessing arterial elasticity prior to arterio venous fistula creation. This pilot study sought to develop an imaging protocol to measure strain in the brachial artery via velocity vector imaging (VVI) and determine if differences in strain could be observed between a healthy group and a group with end-stage renal disease (ESRD), and if VVI measurements were associated with arterio-venous fistula malfunction. 40 healthy volunteers and 33 patients with ESRD were included in this study. All participants underwent US assessment of brachial artery strain via VVI. Peak velocity, strain, strain-rate and velocity were assessed. Patients with and without AVF failure at 3-months were assessed for differences in VVI measurement. Mean VVI measurements between the patient and volunteer groups were similar, and no significant differences were observed. Measurements were reproducible. No significant differences were observed in patients with or without AVF dysfunction. The results from this pilot study suggest VVI measurements of brachial artery mechanics are feasible and that VVI measurements may be used to assess age related changes of the brachial artery.

Reconstruction of aneurismal arteriovenous fistula after arrosive bleeding

Aneurysmal transformation of arteriovenous fistula (AVF) is a common complication and associated with increased risk of arrosive bleeding. Ligation of fistulous vein is conventional surgery for bleeding. This is followed by AVF malfunction and need for implantation of central venous catheter. We report reconstructive surgery and maintaining the function of AVF in a patient with aneurysmal transformation of AVF after arrosive bleeding. Reconstructive vascular surgery can significantly extend the period of patent AVF for hemodialysis. This is extremely important in patients with reduced resources of native vessels suitable for AVF formation. The same is true if conversion of the type of renal replacement therapy is associated with significant difficulties.

Association of Genetic Polymorphisms of Renin-Angiotensin-Aldosterone System-Related Genes with Arterio-Venous Fistula Malfunction in Hemodialysis Patients.

Hemodialysis (HD) is the most commonly-used renal replacement therapy for patients with end-stage renal disease worldwide. Arterio-venous fistula (AVF) is the vascular access of choice for HD patients with lowest risk of infection and thrombosis. In addition to environmental factors, genetic factors may also contribute to malfunction of AVF. Previous studies have demonstrated the effect of genotype polymorphisms of angiotensin converting enzyme on vascular access malfunction. We conducted a multicenter, cross-sectional study to evaluate the association between genetic polymorphisms of renin-angiotensin-aldosterone system and AVF malfunction. Totally, 577 patients were enrolled. Their mean age was 60 years old and 53% were male. HD patients with AVF malfunction had longer duration of HD (92.5 ± 68.1 vs. 61.2 ± 51.9 months, p < 0.001), lower prevalence of hypertension (44.8% vs. 55.3%, p = 0.025), right-sided (31.8% vs. 18.4%, p = 0.002) and upper arm AVF (26.6% vs. 9.7%, p < 0.001), and higher mean dynamic venous pressure (DVP) (147.8 ± 28.3 vs. 139.8 ± 30.0, p = 0.021). In subgroup analysis of different genders, location of AVF and DVP remained significant clinical risk factors of AVF malfunction in univariate and multivariate binary logistic regression in female HD patients. Among male HD patients, univariate binary logistic regression analysis revealed that right-side AVF and upper arm location are two important clinical risk factors. In addition, two single nucleotide polymorphisms (SNPs), rs275653 (Odds ratio 1.90, p = 0.038) and rs1492099 (Odds ratio 2.29, p = 0.017) of angiotensin II receptor 1 (AGTR1), were associated with increased risk of AVF malfunction. After adjustment for age and other clinical factors, minor allele-containing genotype polymorphisms (AA and CA) of rs1492099 still remained to be a significant risk factor of AVF malfunction (Odds ratio 3.63, p = 0.005). In conclusion, we demonstrated that rs1492099, a SNP of AGTR1 gene, could be a potential genetic risk factor of AVF malfunction in male HD patients.

Genotype polymorphisms of genes regulating nitric oxide synthesis determine long-term arteriovenous fistula patency in male hemodialysis patients

Objectives Nitric oxide (NO) is a pivotal vasoactive substance modulating arteriovenous fistula (AVF) patency for hemodialysis (HD). Since genetic background could be the predicting factor of AVF malfunction, we aimed to investigate whether the NO-related genotype polymorphisms determine AVF survival rates. Methods This is a retrospective, observational, multi-center study involving eight HD units in Taiwan, enrolled 580 patients initiating maintenance HD via AVFs. Genotype polymorphisms of NO-biosynthesis regulating enzymes (DDAH-1, DDAH-2, eNOS and PRMT1) were compared between HD patients with (n = 161) and without (n = 419) history of AVF malfunction. Subgroup analyses by gender were performed to evaluate the genetic effect in difference sexes. Results In overall population, statistically significant associations were not found between AVF malfunction and the genetic polymorphisms. In the male subgroup (n = 313), a single nucleotide polymorphism (SNP) of PRMT1, rs10415880 (IVS9-193 A/G), showed a significant association with AVF malfunction. Male patients with AA/AG genotype had inferior AVF outcomes compared to GG genotype, regarding primary patency (70.6% vs. 40.9%, p = 0.001), assisted primary patency (81.0% vs. 58.4%, p < 0.001) and secondary patency (83.7% vs. 63.3%, p < 0.001) at a 5-year observation period. From multivariate Cox regression model, the AA/AG genotypes of PRMT1 were an independent risk factor for AVF malfunction in men (HR: 4.539, 95% CI 2.015–10.223; p < 0.001). However, such associations were not found in women. Conclusions rs10415880, the SNP of PRMT1 could be a novel genetic marker associated with AVF malfunction risk in male HD patients. Those with AA and AG genotypes of rs10415880 may predict a poorer long-term patency of AVF.

Ultrasound-guided Endovascular Treatment for Vascular Access Malfunction: Results in 4896 Cases

For the protracted maintenance of vascular access, countermeasures against stenosis are important. Between March 2004 and October 2011 superficial ultrasound-guided percutaneous transluminal angioplasty (PTA) was performed in our hospital for arteriovenous fistula malfunction in 4869 cases in 1011 patients, and the utility of the treatment was assessed on the basis of early results. In cases where vascular intervention was deemed necessary, the procedure was conducted under ultrasound guidance as first option, with fluoroscopy and radiography used additionally as necessary. The ultrasound apparatus used was primarily the 11 MHz linear-type probe (GE-Yokogawa Logiq S6). For subclavian and brachiocephalic veins, the microconvex-type probe was used to visualize the lesion through the intercostal space. In obstruction cases, ultrasound-guided PTA was performed after superficial ultrasound-guided aspiration or thrombus removal. In stenosis cases, early success (technical and clinical) was obtained in 4288 of 4414 cases (97.1%). In obstruction cases, early success was obtained in 443 cases and 91.9% for obstruction cases. Assistance by intra-operative fluoroscopy or radiography was required in 55 cases, and surgical reconstruction was required in 42 cases. Serious complications occurred in 12 of 4869 cases (0.2%). Ultrasound-guided PTA for arteriovenous fistula malfunction could be used as a substitute for fluoroscopy-guided PTA, and enables the use of safe and rapid intervention techniques.

Effect of Far Infrared Therapy on Arteriovenous Fistula Maturation: An Open-Label Randomized Controlled Trial

Malfunction of the arteriovenous fistula (AVF) is an important cause of morbidity and hospitalization in hemodialysis (HD) patients. The aim of this study is to evaluate the effect of far infrared therapy on the maturation and patency of newly created AVFs in patients with chronic kidney disease stage 4 or 5. Randomized controlled study. Patients with estimated glomerular filtration rate of 5-20 mL/min/1.73 m². 40 minutes of far infrared therapy 3 times weekly for a year. The primary outcome is the rate of AVF malfunction within 12 months, with malfunction defined as either: (1) thrombosis without thrill for AVFs not undergoing HD or (2) receiving any type of interventional procedure due to a lower Kt/V (<1.2) for patients undergoing HD. Secondary outcomes include: (1) cumulative primary unassisted AVF patency, defined as time from creation of the AVF to the first episode of AVF malfunction; (2) physiologic maturation of the AVF by the definition of AVF access blood flow (Qa) ≥500 mL/min and AVF diameter ≥4 mm at 3 months; and (3) clinical maturation of the AVF suitable for HD at 1 year. AVF Qa was measured by Doppler ultrasonography at 2 days and 1, 2, 3, and 12 months. We enrolled 122 patients who were randomly allocated to the intervention (n = 60) and control (n = 62) groups. In comparison to controls, patients in the intervention group had higher Qa values at 1, 2, 3, and 12 months; a higher rate of physiologic maturation (90% vs 76%; P = 0.04) at 3 months; and a lower rate of AVF malfunction (12% vs 29%; P = 0.02) but higher rates of AVF cumulative unassisted patency (87% vs 70%; P = 0.01) and clinical maturation (82% vs 60%; P = 0.008) within 12 months. This is a single-center nonblinded study. Far infrared therapy improves the access flow, maturation, and patency of newly created AVFs in patients with chronic kidney disease stages 4 and 5.

Length polymorphisms of heme oxygenase-1 determine the effect of far-infrared therapy on the function of arteriovenous fistula in hemodialysis patients: a novel physicogenomic study

The objective of this study was to evaluate the interaction between the length polymorphism of the guanosine thymidine repeat [(GT)n] in the heme oxygenase-1 (HO-1) gene and far-infrared (FIR) therapy on access flow (Qa) and arteriovenous fistula (AVF) patency in hemodialysis (HD) patients. A total of 280 HD patients were randomized into a control group (n = 141) and the FIR group (n = 139) who received 40 min of FIR therapy three times weekly for a year during the study period from May 2005 to December 2007. Access flow was measured during HD. The [(GT)n] was determined with the definition of long (L) allele as [(GT)n] ≥ 30 and short (S) allele as [(GT)n] < 30. The Qa decreased from S/S to S/L and further to the L/L group but increased by FIR therapy with the highest Qa increase in the S/S group. The incidence of AVF malfunction decreased both from the L/L, S/L to S/S group (32.4 versus 17.2 versus 10.9%, P = 0.007) and from the control group to FIR group (27.5 versus 12.6%, P = 0.004). Significant associations were found between AVF malfunction and the following factors (hazard ratio, P-value): a past history of AVF malfunction (2.45, P = 0.044), FIR therapy (0.369, P = 0.03) and L/L genotypes of HO-1 (2.531 versus S/S + S/L genotypes). The 1-year unassisted patency decreased from 91.9 and 77.6% in S/S and S/L subgroups with and without FIR therapy to 75.8 and 60% for L/L subgroup with and without FIR therapy, respectively (P < 0.001). FIR therapy improves Qa and patency of AVF in HD patients, with the best protective effect in those with S/S genotype of HO-1.

Superoxide in AVF dysfunction: a new target for intervention

an adequately functioning vascular access is an absolute requisite for patients receiving hemodialysis. Among the three currently available (fistulae, grafts, and tunneled catheters) vascular accesses, the arteriovenous fistula (AVF) is considered the “gold standard” and is the most common mode

Anthropometric Parameters of Nutritional Assessment as Predictive Factors of Arteriovenous Fistula Malfunction in Patients Undergoing Hemodialysis

To evaluate the role of body mass index (BMI), waist circumference (W-C) and waist/hip ratio (WHR) on arteriovenous fistula (AVF) dysfunction. We evaluated 84 HD patients with an average follow-up period of 31.3 ± 8.1 months, identifying 8 stenosis (STN) and 17 thrombosis (THR) cases. The association between paired variables was tested with Pearson's coefficient (r) and p-value, whereas the prognostic value on STN and THR was analysed using Cox's regression. The significant independent variables were indentified with an inverse step-wise approach defining the data as hazard ratio (HR). A double-event (Stenosis/Thrombosis) model, function of Body mass index and Waist/hip ratio was used. Arteriovenous fistula survival was assessed with the Kaplan-Meyer curve and the calculations were carried out with Graph-Pad. On univariate analysis, THR showed direct correlation with BMI (r=0.44, p<0.01), W-C (r=0.39, p<0.05) WHR (r=0.37, p<0.01), Hemoglobin (p<0.001), C-Reactive protein (p=0.01), Calcium/Phosforus product (p=0.03), Parathyroid hormone (p=0.03) and inverse with albumin (p<0.001) and systolic blood pressure (p=0.003). On multivariate analysis, BMI variations were not predictive of STN and THR, whereas each unitary WHR and W-C increase was predictive of an increase of risk of events (3.8% and 2.1% respectively). The prognostic power of W-C per STN (HR 1: 1.19; p<0.05) and THR (HR: 1.28; p<0.01) remained significant even after being adjusted to account for traditional risk factors. Abdominal obesity increases the risk of AVF dysfunction. The W-C and WHR parameters, not BMI, emerge as independent STN and THR predictors.

Should a Double-Lumen Catheter be withdrawn?

Haemodialysis needs a credible and recurrent access to the systemic circulation which can be accomplished by way of central vein catheterization. We report the case of bleeding after withdrawal of the double lumen catheter. A 36-year-old woman who was a known case of end-stage renal disease referred to a dialysis center because of her arteriovenous fistula malfunction. A double-lumen catheter was inserted via the right internal jugular vein but failed to become functional so in the emergency department we decided to withdrawal catheter under cardiac monitoring and pulse oximetry but unfortunately A few minutes after the withdrawal of the double lumen Catheter the patient became agitated and confused. The resuscitation team after infusing IV fluid and blood decided to emergent thoracotomy. We control bleeding by direct pressure and repaired a rupture of the posterior aspect of the right internal jugular and right subclavian vein junction. Six hours later she became alert and one week after discharged, she was in well general condition.

Long-term Effects of Arteriovenous Fistula Closure on Echocardiographic Functional and Structural Findings in Hemodialysis Patients: A Prospective Study

The arteriovenous fistula (AVF) provides an effective vascular access for hemodialysis; however, the associated hemodynamic effects may alter cardiac structure and function. The objective of this study is to evaluate the effect of AVF closure on functional and structural echocardiographic findings. Prospective observational study. In a single center between 2003 and 2006, we enrolled 25 consecutive hemodialysis patients with AVF malfunction who underwent AVF closure and conversion to a tunneled central venous catheter because of exhaustion of alternative vascular sites and 36 matched controls with a well-functioning AVF. AVF closure. Outcomes were changes in findings on echocardiograms obtained before and 6 months after AVF closure for patients in the AVF-closure group and at baseline and 6 months later for controls. Echocardiographic measurements included left ventricular (LV) internal diastolic diameter, interventricular septum thickness, diastolic posterior wall thickness, LV mass (LVM), LVM index (LVMi), and LV ejection fraction (LVEF). Dialysis modality and scheme were unchanged. In the AVF-closure group, LVM decreased from 225 +/- 55 to 206 +/- 51 g (P < 0.001) and LVMi decreased from 135 +/- 40 to 123 +/- 35 g/m(2) (P < 0.001). LV internal diastolic diameter, interventricular septum thickness, and diastolic posterior wall thickness decreased significantly, whereas LVEF increased from 56% +/- 7% to 59% +/- 6% (P < 0.001). No significant changes were observed in controls. In patients with AVF closure, LV morphologic characteristics showed a decrease in both eccentric and concentric hypertrophy in favor of normalization or a pattern of concentric remodeling. No significant changes were observed in controls. Use of matched rather than randomized controls. Closure of an AVF determines a significant decrease in LV internal diastolic diameter, interventricular septum thickness, and diastolic posterior wall thickness. This is associated with significant improvement in LVEF, a significant decrease in LVM and LVMi, and a more favorable shift of cardiac geometry toward normality.

Why “fistula first” matters: Increased durability, less interventions, and decreased costs

Over the past 15 year, the National Kidney Foundation has recognized the overall poorer results with prosthetic arteriovenous graft (AVG) placement over an arteriovenous fistula (AVF) creation. To this end, it made clear recommendations that AVF creation should approach 65% of all hemodialysis access thru the now well-known Kidney Disease Outcomes and Quality Initiative (KDOQI) guidelines. AVF creation over AVG placement has now become the ‘‘gold-standard’’ and is primarily done by most surgeons when technically feasible. Unfortunately, AVF malfunction occurs from three major sources: stenoses of the juxta-anastomotic region, intra-AVF stenosis likely due to vein mobilization during the AVF creation, or outflow venous stenosis formation due to intimal hyperplasia and hemodynamic strain. Hence, when AVFs malfunction, intervention thru percutaneous transluminal angioplasty (PTA) is usually required. Conversely, AVGs tend to thrombose more readily than AVFs but because it is a synthetic conduit, the majority of the stenoses are anastomotic (venous primarily and, rarely, arterial). Therefore, when an AVG malfunctions, it is usually due to a thrombotic event, necessitating a percutaneous thrombectomy with an adjunctive PTA and/or stenting procedure to treat the underlying lesion. The AVF vs. AVG issue is further complicated by the fact that various studies have found that AVF creation is associated with a prolonged maturation time and, therefore, an increased initial central venous catheter use. Given these two types of accesses, what are the economic costs associated with keeping them functional and does an aggressive angiography program help prevent access thrombosis? Bittl et al tackle these questions in this issue of CCI through a 7-year economic analysis of over 800 patients with stage V chronic kidney disease, 560 of who required at least one intervention. They found that the median number of access angiograms per patient was 3, underscoring the commitment required for such a patient population to keep an access functional. Their results are in line with the growing literature that in per patient years, AVGs require almost twice as many interventions than AVFs to maintain patency. Moreover, they found a fourfold greater rate of thrombotic events in AVGs over AVF; as the rate of AVF creation increased, there was a decrease in the thrombotic rate. They next attempted to determine if a lower thrombosis rate was due to a preemptive angiography program of AV accesses. Logistic regression did suggest that both of these contributed to the lowering of the thrombotic rates independently; however, because of the increased rate of AVF creation during the study period, it is difficult to separate these two possibly confounding variables. So, is it cost-saving to do preemptive angiography on arteriovenous accesses? The answer is yes, if the rate of AVF creation is also high (over 65% as KDOQI guidelines suggest). A predominance of AVF creation is likely the largest contributor of cost-reduction. In the future, studies to determine which AVF stenoses should be treated to keep them functional will help guide how aggressive a preemptive angiography program to implement. In the mean time, we can conclude that KDOQI guidelines also seem to make economic sense.

Stent placement for treatment of central and peripheral venous obstruction: A long-term multi-institutional experience

Purpose: The clinical success and patency of central and peripheral venous stents in patients with symptomatic venous obstruction (SVO) were assessed. Methods: The records of patients with SVO treated with venous stents from 1992 to 1999 were reviewed. Demographic and procedural variables were analyzed to determine their effect on clinical success, primary patency, and secondary patency. Patency was determined by means of a follow-up duplex scan or venogram. Results: Forty central venous (CV) and 14 peripheral venous (PV) obstructions were treated in 49 patients. Sixty-five stents were placed (50 CV and 15 PV), 54 in previously unstented lesions and 11 in previously stented lesions. Causes of CV lesions included catheter placement (82%), tumor compression (6%), arteriovenous fistula (AVF) and no prior catheter (2%), and other (10%). All PV lesions resulted from complications of dialysis. Indications for CV stents included limb edema (46%), AVF malfunction (30%), both limb edema and AVF malfunction (14%), and other (10%). PV stent indications were AVF malfunction (86%) and limb edema (14%). Thirteen CV stents indicated to treat tumor compression (three cases), May-Thurner syndrome (one case), deep venous thrombosis (three cases), superior vena cava syndrome (one case), and lower-extremity catheter-related lesions (five cases) were excluded from the analysis of clinical outcome. Fifty-two stents (37 CV and 15 PV) were included in the analysis of clinical outcome. All CV lesions included in the analysis were complications of prolonged catheterization. Eighty-nine percent of patients had end-stage renal disease and an AVF. Complications developed in 26% of patients with PV stents and in no patients with CV stents (P <.002). The mean follow-up period was 16 months. Sixty-two percent of patients required a reintervention for recurrent SVO. Only 32% of the interventions resulted in sustained symptomatic improvement. For CV stents, the primary patency rate was 85%, 27%, and 9% at 3, 12, and 24 months, respectively; the secondary patency rate was 91%, 71%, and 39% at 3, 12, and 24 months, respectively; and the clinical success rate was 94%, 94%, and 79%, at 3, 12, and 24 months, respectively. For PV stents, the primary patency rate was 73%, 17% and 17% at 3, 12, and 24 months, respectively; the secondary patency rate was 80%, 56%, and 35% at 3, 12, and 24 months, respectively; and the clinical success rate was 92%, 75%, and 42% at 3, 12 and 24 months, respectively. Conclusion: Stents provide a temporary benefit in most patients with central or peripheral upper-extremity SVO. Regular follow-up and reinterventions are required to maintain patency and achieve long-term clinical success. Stents used for CV lesions have higher clinical success rates than stents used for PV lesions. Patients with a reasonable life expectancy or who are unable to return for subsequent procedures should be considered for undergoing alternative therapy. (J Vasc Surg 2000;32:760-9.)