Fistula Maturation Rate Research Articles

Vas Q – An Innovative External Support Device Improves Functionality of Arteriovenous Fistulas: Pilot Study Results

Introduction: Patients in need of dialysis treatment depend on vascular access. Arteriovenous fistula (AVF), is the gold standard for access, however, while superior to other access methods, it is associated with high early failure rates which necessitates frequent interventions intended to maintain AVF functionality. Large series have shown that although native AVFs have a low rate of complications and improved longevity of use when functional, they suffer from relatively poor early patency rates with more than half being unsuitable for dialysis use by one year. The precise reasons for these early failures remain to be fully elucidated, although it is clear that inability to increase inflow often results from perianastomotic stenosis and venous neointimal hyperplasia. Turbulent flow has been identified as a driver for neointimal hyperplasia and as a cause of stenosis. VasQ, is a new external support device, implanted over the arteriovenous fistula. Targeting the juxta-anastomotic area, the VasQ adjusts anastomosis geometry, regulates flow patterns, and supports the venous wall thereby facilitating fistula maturation and longevity. We present results of a Pilot prospective study, enrolling 20 patients with a follow up period of 6 months. Study objectives included assessment of the implantation procedure and fistula maturation and patency rates. Methods: The trial was conducted as a prospective, single-arm study design so as to determine device safety and initial efficacy. The study was conducted at St. George's Vascular Institute, St. George's University Hospitals Foundation Trust, London, UK. 20 patients were enrolled. Patients were eligible if they were referred for creation of a new brachiocephalic fistula with non-stenotic vein and artery diameter ≥3 mm, and free of significant co-morbidities which can prevent study completion. The VasQ device was threaded proximally on the vein prior to anastomosis suturing and subsequently lowered distally onto the anastomosis after completion. Patients were followed for 6 months post-procedure, with Doppler ultrasound examinations performed at 1, 3, and 6 months. Fistula was considered matured if Doppler measurements showed venous outflow ≥500 ml/min and vein diameter ≥5 mm. Results: Between June 2014 and January 2015, two surgeons implanted VasQ in 20 patients. Device implantation easily integrated with the routine fistula procedure. All patients were free from any device related complications. One patient died following a myocardial infarction. At 1, and 3 months fistula maturation rate were 75% and 79%, Primary patency rates at 1, 3 and 6 months were 95%, 79% and 79%. mean outflow rates at 1, 3 and 6 months were 1130 ml/min and 1426 ml/min, and 1304 ml/min. mean vein diameters were 6.6 mm, 8.4 mm and 10 mm at 1,3 and 6 months respectively. Conclusion: The VasQ used in autogenous brachiocephalic AVFs is associated with higher short- and medium-term maturation and patency rates for externally supported AVFs than previously reported. Larger, longer-term prospective studies are required in order to confirm these promising results. VasQ may obviate some of the problems implicated in early AVF failure providing a fixed outflow diameter and shielding the anastomosis from adhesions and inflammatory reaction. Disclosure of Interest: None Declared.

Pulmonary Hypertension and Hemodialysis Access

The purpose of this project was to identify the patient's features and the technical factors related to an increased risk of heart failure with the creation of dialysis vascular access (DVA). The study included 269 patients with chronic kidney disease who had a baseline and postoperative echocardiogram within 6 months of fistula creation at a single institution between January 2000 and March 2015. There were 37 patients with α1-antitrypsin disease, pulmonary fibrosis or sarcoidosis, and a heart or lung transplant who were excluded, leaving 232 patients in the final cohort. Patients with pulmonary hypertension (pHTN; n = 70 [30.2%]) were compared with patients without pHTN (n = 162 [69.8%]). Patients with pHTN were younger (P = .01) and were less likely to have congestive heart failure (P = .032), peripheral vascular disease (P = .044), or history of a percutaneous coronary intervention (P = .018). Patients with pHTN were more likely to have obstructive sleep apnea (P = .023). Survival was not affected by pHTN status (P = .16). The overall fistula maturation rate (defined as successful two-needle cannulation for 4 weeks) was 78.9%. An upper arm arteriovenous fistula (P = .46), an infraclavicular nonautologous graft of any diameter (P = .38), a two-stage surgery (P = .14), the history of a prior dialysis catheter (P = .56), and pharmacomechanical thrombectomy (P = .98) were not associated with the development pHTN. Patients who underwent cleaner thrombectomy (P = .048) or a subsequent 4- to 7-mm chest wall graft (P = .031) after the index fistula failed were more likely to have pHTN. Only one patient had the fistula ligated for worsening heart failure. Patients who experienced the onset of pHTN after DVA (DVA-pHTN; n = 34 [48.6%]) were compared with patients who had pHTN before DVA (pHTN-DVA; n = 36 [51.4%]). pHTN-DVA patients were less likely to have a history of a myocardial infarction (P = .029). There is no difference in the mean change in right ventricular systolic function after arteriovenous fistula creation in comparing patients with pHTN with patients without pHTN (P = .067) and comparing DVA-pHTN with pHTN-DVA (P = .77). DVA surgery does lead to pHTN, and patients should be monitored for the development of clinically significant symptoms that merit intervention. In general, it is safe to create DVA and to perform the necessary maintenance interventions regardless of the presence or severity of pHTN. Direct central venous outflow may pose a higher risk for severe pHTN warranting DVA ligation.

A novel factor for primary arteriovenous fistula failure: hyperinsulinism

Introduction: Dysfunction of vascular access is an important reason of morbidity for dialysis patients and it is a major factor affecting the economical burden of hemodialysis. The preferred type of vascular access is creation of an arteriovenous fistula (AVF). However, the problem of fistula maturation rate is still a challenge. Herein, we tried to search the role of hyperinsulinism and insulin resistance as a new predictor of primary AVF failure (pAVFF) that may be a cause of intimal damage.Methods: We included 119 patients (73 male and 46 female) with a diagnosis of end-stage renal disease (ESRD) who had undergone an AVF operation by a vascular surgeon. The AVF was examined for presence of thrill on the first postoperative day. A successful cannulation with two fistula needles with a blood flow of 250 mL/min for at least one complete dialysis session, after 4 weeks of AVF surgery was defined as functioning access. Insulin resistance in our patients was determined by the standard homeostasis model assessment (homa-IR). A logistic-regression analysis was performed to investigate the independent factors related with pAVFF.Findings: Detection of pAVFF occurred in 27 (22.7%) patients. The presence of thrill, amount of daily proteinuria, insulin levels, homa-IR, and serum albumin levels were found to be significantly different between patients with fistula failure and those without pAVFF. The logistic-regression analysis of preoperative factors revealed the following OR (odds ratio) and 95% CI values: homa-IR 1.205 (1.063–1.366) (p = 0.004), serum albumin 0.398 (0.178–0.892) (p = 0.025), and the amount of daily proteinuria 1.307 (1.012–1.688) (p = 0.041). Even after addition of the presence of postoperative thrill on AVF, which was a postoperative strong clinical factor to the analysis, mean homa-IR and mean serum albumin continued to be independent predictors of pAVFF.Discussion: Insulin resistance or hyperinsulinism may be a significant cause of pAVFF, which emphasizes the role of endothelium in fistula dysfunction.

Dialysis Access Surgery: Does Anesthesia Type Affect Maturation and Complication Rates?

Creation of an arteriovenous fistula (AVF) is the preferred method of establishing long-term dialysis access. There are multiple anesthetic techniques used for patients undergoing this surgery including general endotracheal intubation, laryngeal mask airway, regional anesthesia with nerve blocks, and monitored anesthesia care with local infiltration. It is unclear what effect the method of anesthesia has on AVF creation success rate. It is our objective to determine if anesthesia type affects success of these surgeries defined by complication and maturation rates. A retrospective review was performed in a single institution, single surgeon study of 253 patients who underwent AVF creation between January 2003 and December 2010. Patients were cross analyzed between 3 anesthesia types (General Endotracheal Intubation, Laryngeal Mask Airway and Local Infiltration with Monitored Anesthesia Care) and AVF creation surgeries (radiocephalic, brachiocephalic, and basilic vein transposition). No patients had regional anesthesia performed. Demographic data including comorbidities and risk factors were stratified among all categories. Analysis of variance, chi-squared testing, and Fisher's exact P testing was performed across all anesthesia types and specific operations and measured according to success of fistula maturation and complication rates (including death within 30days, myocardial infarction within 30days, respiratory insufficiency, venous hypertension, wound infections, neuropathy, and vascular steal syndrome). There were no significant differences in maturation rate in terms of all 3 anesthesia types for radiocephalic (P=0.191), brachiocephalic (P=0.191), and basilic vein transposition surgeries (P=0.305). In addition, there were no differences in complication rates between the surgeries and the 3 types of anesthesia (P=0.557). Our study shows that despite anesthesia type, outcomes in terms of maturation and complication rate are not statistically different in AVF creation surgeries. The use of monitored anesthesia care with local anesthesia may improve operative efficiency in terms of time in the operating room and in the recovery unit and therefore may be the preferred method of anesthesia. This recommendation may also parallel the preference to avoid general anesthesia in a patient population with more medical comorbidities. It is our conclusion that dialysis access surgery should therefore be performed under local anesthesia with monitored anesthesia care.

Preoperative vascular access evaluation for haemodialysis patients.

Haemodialysis treatment requires reliable vascular access. Optimal access is provided via functional arteriovenous fistula (fistula), which compared with other forms of vascular access, provides superior long-term patency, requires few interventions, has low thrombosis and infection rates and cost. However, it has been estimated that between 20% and 60% of fistulas never mature sufficiently to enable haemodialysis treatment. Mapping blood vessels using imaging technologies before surgery may identify vessels that are most suitable for fistula creation. We compared the effect of conducting routine radiological imaging evaluation for vascular access creation preoperatively with standard care without routine preoperative vessel imaging on fistula creation and use. We searched Cochrane Kidney and Transplant's Specialised Register to 14 April 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review. We included randomised controlled trials (RCTs) that enrolled adult participants (aged ≥ 18 years) with chronic or end-stage kidney disease (ESKD) who needed fistulas (both before dialysis and after dialysis initiation) that compared fistula maturation rates relating to use of imaging technologies to map blood vessels before fistula surgery with standard care (no imaging). Two authors assessed study quality and extracted data. Dichotomous outcomes, including fistula creation, maturation and need for catheters at dialysis initiation, were expressed as risk ratios (RR) with 95% confidence intervals (CI). Continuous outcomes, such as numbers of interventions required to maintain patency, were expressed as mean differences (MD). We used the random-effects model to measure mean effects. Four studies enrolling 450 participants met our inclusion criteria. Overall risk of bias was judged to be low in one study, unclear in two, and high in one.There was no significant differences in the number of fistulas that were successfully created (4 studies, 433 patients: RR 1.06, 95% CI 0.95 to 1.28; I² = 76%); the number of fistulas that matured at six months (3 studies, 356 participants: RR 1.11, 95% CI 0.98 to 1.25; I² = 0%); number of fistulas that were used successfully for dialysis (2 studies, 286 participants: RR 1.12, 95% CI 0.99 to 1.28; I² = 0%); the number of patients initiating dialysis with a catheter (1 study, 214 patients: RR 0.66, 95% CI 0.42 to 1.04); and in the rate of interventions required to maintain patency (1 study, 70 patients: MD 14.70 interventions/1000 patient-days, 95% CI -7.51 to 36.91) between the use of preoperative imaging technologies compared with standard care (no imaging). Based on four small studies, preoperative vessel imaging did not improve fistula outcomes compared with standard care. Adequately powered prospective studies are required to fully answer this question.

Salvage of Early-Failing Radiocephalic Fistulae with Techniques that Minimize Venous Dissection

Although radiocephalic fistulae are the preferred hemodialysis access, juxta-anastomotic stenosis is often responsible for early fistula failure. We hypothesized that wall ischemia from surgical manipulation leads to early juxta-anastomotic neointimal hyperplasia and failure of maturation and that minimal venous dissection will improve surgical salvage, increasing fistula maturation rates. For failing-to-mature radiocephalic fistulae that develop early juxta-anastomotic stenosis, we describe 3 variations to perform a new proximal anastomosis with a minimal dissection technique on the forearm cephalic vein: (1) side-to-side anastomosis, (2) radial artery deviation and reimplantation, or (3) radial artery deviation and loop reimplantation. Minimal dissection of the cephalic vein achieves fistula salvage without needing a more proximal site for access.

Increased use of brachiocephalic arteriovenous fistulas improves functional primary patency

As vascular surgeons strive to meet the Fistula First Initiative, some authors have observed a decrease in arteriovenous fistula (AVF) maturation rates in association with an increase in AVF creation. In May 2012, we adopted a practice change in an attempt to maintain the same high level of AVF creation while leading to a decrease in fistula failures. A retrospective study was conducted of all dialysis access procedures performed by a single vascular surgeon before (period 1; before May 1, 2012) and after (period 2; after May 1, 2012) the change in practice pattern. The adopted change included favoring the brachiocephalic location unless the patient was an ideal anatomic candidate for a radiocephalic AVF, creating a larger and standardized arteriotomy, and using a large venous footplate whenever possible. The main outcome measure was primary functional patency at 1 year. Secondary outcome measures included primary patency at 1 year, time to maturation, type of fistula created, steal syndrome, and tunneled hemodialysis catheter infections. Of 213 vascular access procedures performed, 191 (90%) were AVFs. There was no difference in use of AVFs between period 1 (93% AVFs) and period 2 (88% AVFs; P = .2). Use of brachiocephalic AVFs increased from 38% in period 1 to 56% in period 2 (P = .01), with a corresponding trend toward a decrease in radiocephalic AVFs in period 2 (36% in period 1 to 27% in period 2; P = .2). Primary functional patency at 1 year was 47% in period 1 and 63% in period 2 (P = .03). Primary patency at 1 year was 51% in period 1 and 70% in period 2 (P = .001). Time to reach functional maturation was decreased in period 2 (median, 76 vs 82.5 days; P = .046). There was no difference in steal syndrome (P = 1.0), and the incidence of hemodialysis catheter infections was lower in period 2 (0 vs 7 [7%]; P = .006). Increasing brachiocephalic AVF creation and reducing our reliance on radiocephalic AVFs resulted in a significant increase in primary functional patency at 1 year. This was achieved while maintaining the same high percentage of fistulas, a lower rate of central catheter infections, and the same low incidence of steal syndrome.

Randomized controlled trial comparing primary and staged basilic vein transposition.

It is unclear if brachio-basilic vein fistula should be performed as a primary or staged procedure, particularly for smaller basilic veins. Our aim was to report on a randomized controlled trial comparing these two techniques. Sixteen patients with a basilic vein ≥2.5 mm were randomized into primary transposed brachio-basilic vein (TBBV) fistula (n = 9) and staged TBBV fistula (n = 7). Patients with basilic veins enlarged by previous arteriovenous fistulas were excluded. Baseline characteristics of the two study groups, including vein size, were comparable (median basilic vein diameter 3.5 mm, range 2.8-4.1 mm). The staged group had a brachio-basilic vein fistula performed first followed by the transposition procedure performed at least 6 weeks later to allow the basilic vein to enlarge. TBBV fistula maturation at 10 weeks, primary, assisted-primary, and secondary patency were the primary outcome measures. Early failures were included in the calculation of patency rates. Transposed brachio-basilic vein fistula maturation rate after primary procedures (3/9, 33%) was lower compared to maturation rate after staged procedures (7/7, 100%, P = 0.011, Fisher's exact test), which led to premature termination of the trial. Time to hemodialysis [median (interquartile range)] of primary and staged procedures was 54 (51.5-113.5) days and 97 (93-126) days, respectively (P = 0.16). One-year primary and assisted-primary patency rates of primary and staged procedures were equivalent (44 vs 57%, P = 0.76 and 44 vs 71%, P = 0.29, respectively); however, there was a trend toward a better 1-year secondary patency after staged procedures (86 vs 44% for primary procedures, P = 0.09). Among candidates for TBBV fistula with a small basilic vein, staged transposition achieves higher maturation rates compared to primary procedures, a difference reflected in long-term secondary patency. www.ClinicalTrials.gov, identifier NCT01274117.

Review of transposed basilic vein access for hemodialysis.

There is ongoing debate about the use of transposed basilic vein (TBV) fistula and the choice between it and prosthetic arteriovenous graft (AVG). This paper reviews the available literature relating to TBV fistula in terms of surgical technique, patency rates, complications, access survival and compares it with prosthetic AVG for hemodialysis (HD). Review of English language publications on TBV during the last two decades. The rate of fistula maturation was higher in the two-stage group, although the mean diameter of the basilic vein was smaller. Dialysis via central venous catheters at time of surgery was most prevalent in patients undergoing staged procedures—14% in one-stage TBV and 43% in two-stage TBV. Several authors report 1-year cumulative patency rate of 47% to 96% and 59% to 90% for TBV and AVG, respectively. TBV provides a more cost-effective option and should be considered the next choice when primary autogenous fistulae are not possible, whereas AVGs are easier to create, can be punctured earlier and have a greater reintervention rate if the access fails. This analysis shows that TBV has several advantages over AVG and provides a valuable access for HD but raises the need for a comparative trial between TBV and the newer generation AVGs. There is no clear superiority of the one-stage over the two-stage procedure.

Accessory veins in nonmaturing autogenous arteriovenous fistulae: analysis of anatomic features and impact on fistula maturation.

The appropriate management of nonmaturing arteriovenous (AV) fistulae continues to be a controversial issue. While coil embolization of accessory side-branch veins can be performed to encourage maturation of nonmaturing AV fistulae, the true efficacy and optimal patient population are not well understood. Fistulagrams performed on nonmaturing AV fistulae were retrospectively reviewed in 145 patients (86 males, median age 63years) for the presence of accessory veins. Fistula and accessory vein measurements were obtained, as were rates of eventual fistula maturation after accessory vein coil embolization. Of 145 nonmaturing fistulae, 49 (34%) had a stenosis without any accessory veins, 76 (52%) had a stenosis and one or more accessory veins, and 20 (14%) had an accessory vein without concurrent stenosis. Eighteen AV fistulae had one or more accessory veins without coexisting stenosis. Nine fistulae had a caliber decrease immediately downstream from the accessory vein. Coil embolization of dominant accessory veins with a caliber decrease immediately downstream (n=6) resulted in a 100% eventual fistula maturation rate versus 67% for fistulae without this configuration (n=6, p=0.15). Accessory vein size was not correlated with maturation rates (p=0.51). The majority of nonmaturing fistulae with accessory veins had a coexisting stenosis. Higher maturation rates may result with selected anatomic parameters, although additional studies with more robust sample sizes are needed prior to definitive conclusions.

Effect of clinical examination and anatomical location on native arteriovenous fistula maturation rate in high risk patients

Introduction: Maximal use of native arteriovenous fistulas (AVFs) for patients on hemodialysis therapy remains a clinical challenge. Primary failure rates remain high with risk factors such as female gender, diabetes mellitus, lower arm AVF and higher age. We wondered if a strategy of careful clinical examination prior to AVF creation and a preference towards an upper arm AVF in case of doubt about the quality of the vein in patients with any of the above mentioned risk factors, would lead to better maturation rates.Methods: The records of all patients who received an AVF between January 2005 and December 2009 at our University Hospitals Leuven were studied retrospectively. Demographic data, comorbidity, fistula characteristics, fistula maturation and fistula complications were recorded and analyzed.Results: Of 344 patients enrolled, 156 (45.3%) received a lower arm AVF and 188 (54.7%) an upper arm AVF. Two hundred and seventy-six (80.2%) fistulas had a normal maturation. Lower arm AVF was a significant risk factor for non-maturation in this series (73.1% versus 86.2%; p = 0,0024). Female gender, diabetes and high age were not, but female gender showed a significant difference in distribution in upper arm versus lower arm fistulas (62.40% versus 37.6%; p = 0,0218).Conclusion: Careful clinical examination prior to upper or lower arm AVF creation together with the integration of risk assessment in the planning of AVF is worthwhile. A preference towards upper arm fistulas if major risk factors are present can improve overall maturation rates and lead to the same maturation rates as in the overall dialysis population. Therefore, the presence of risk factors for non-maturation should not lead to the underuse of native AVFs.

Outcomes of Single‐Stage Compared to Two‐Stage Basilic Vein Transposition Fistulae

Basilic vein transposition (BVT) fistulae are increasing in prevalence in the United States. We examined outcomes of BVT fistulae created in a single stage compared to those created in two stages. Prospective QA databases identified a consecutive cohort of 144 patients with BVT fistulae. Of these, 42% were created in one stage and 58% in two stages. Fistula maturation rates, mean time to fistula use and intensity of percutaneous interventions were compared; patency rates were compared from time of first intervention. Maturation rates (including assisted maturation) were 90% among 1-stage and 75% among 2-stage BVT (p = 0.02). Mean time to initiation of fistula use was 142 days (1-stage) and 146 days (2-stage) (p = 0.92). Intensity of percutaneous interventions was 1.84/patient-year of dialysis (PYD) (1-stage) and 2.15/PYD (2-stage) (p = 0.57). Secondary patency at 1, 2, 3, and 4 years for 1-stage BVT was 86%, 75%, 69%, and 57%; secondary patency at 1, 2, 3, and 4 years for 2-stage BVT was 76%, 71%, 49%, and 25%, respectively (p = 0.12). BVT creation in two stages confers only a modest reduction in maturation rates and secondary patency and therefore should be considered over a synthetic graft in patients with basilic veins deemed inadequate for 1-stage BVT.

Surgical Revision for Non-Maturing Arteriovenous Fistulas

Arteriovenous fistulas (AVF) are the preferred access for patients who require hemodialysis. However, some AVFs require additional surgery to augment maturation. This study determined the effectiveness of AVF revision and the clinical characteristics of patients with poorly maturing fistulas. All AVFs performed over a 5-year period (January 2006-December 2011) were reviewed, classified as radial-cephalic (RC), brachial-cephalic (BC), brachial-basilic transposition (BVT), and brachial-brachial (BB). Technical factors and co-morbidities for patients with AVFs that matured without assistance were compared with fistulas that required revision or were abandoned. Data were evaluated on a per-patient basis (χ2 and t-test, P value <.05) 292 AVFs were created in 250 patients. 134/250 fistulas (53.6%) matured without assistance within an average of 71 days. Patients with AVFs that matured without revision were more likely to be male (60.6% vs 42.1%; P < .01), have a lower BMI (26.9 vs 29.8; P < .01), and a larger preoperative vein diameter (3.83 mm vs 3.42 mm; P < .02). 54 of 116 non-matured AVFs were revised (70% RC, 26% BC, 4% BVT). The more common revisions were branch ligation (52%), superficial transposition (31%), and anastomotic revision (30%). 89% required one, 9% two, and 2% required three revisions to achieve maturation. Average time from index AVF creation to maturation in revised patients was 209 days. 42/54 patients (79.2%) developing a usable fistula, increasing the overall maturation rate to 70.4%. The most common cause for abandoning a non-mature fistula was thrombosis (62%). Surgical revision for poorly maturing AVFs increases overall fistula maturation rates as much as 17%.

8:08 AM Abstract No. 71 - Accessory veins in failure-to-mature autogenous av fistulas: correlation with fistula caliber changes and success rates of maturation after coil embolization

Purpose The clinical significance and hemodynamic impact of accessory veins on AV fistula maturation is poorly understood. While fistula maturation depends on arterialized flow, accessory veins divert flow away from the downstream aspect of the fistula. The purpose of this study was to determine if the size and presence of accessory veins correlates with caliber changes in the fistula and whether any such characteristics correlate with fistula maturation when accessory veins are embolized. Materials and Methods Between 1/2006 and 7/2011, 145 patients (86 males, mean age, 62 years) were referred for an AV fistulagram for failure to mature. Fistulagrams were retrospectively reviewed for presence of accessory veins at least 20% of the diameter of the fistula. Fistula diameters were measured immediately upstream and downstream to the dominant accessory vein, as was the diameter of the accessory vein. A drop in fistula diameter was deemed present if the fistula diameter downstream to the accessory vein was greater than a 5% decrease from the upstream diameter. Medical records were reviewed to determine the rate of eventual fistula maturation after accessory vein coil embolization. Results Of the 96 AV fistulas with accessory veins, 49% demonstrated a drop in fistula diameter immediately downstream to the accessory vein. The caliber of the accessory vein did not correlate significantly with the likelihood of a downstream drop in AV fistula caliber. A co-existing >50% stenosis in the AV fistula or outflow was present in 76 patients. In the 20 AV fistulas with accessory veins but without any co-existing stenosis, a drop in AV fistula diameter downstream to the accessory vein (n=9) was associated with a 100% rate of fistula maturation after accessory vein embolization compared to a 45% maturation rate for fistulas without a drop in fistula caliber (n=11, p=0.01, chi-square test). Conclusion The caliber of accessory veins in failure-to-mature AV fistulas did not correlate with a drop in the downstream fistula diameter. However, coil embolization of accessory veins was significantly more successful if the fistula caliber dropped at least 5% immediately downstream to the accessory vein.

8:16 AM Abstract No. 72 - Outcomes of single-stage compared to two-stage basilic vein transposition fistulae

Purpose Basilic vein transposition (BVT) fistulae are increasing in prevalence in the U.S. as more patients undergo dialysis through an autologous access. We examined whether BVT fistulae created in a single operation (1-stage) differ in outcomes compared to those requiring two stages due to small caliber ( Materials and Methods Surgical access records and IR QA databases were used to identify a consecutive cohort of 144 patients with BVT fistulae (66 M: 78F). Of these, 61 (42%) underwent BVT fistula creation in a single operation; 83 (58%) underwent BVT fistula creation in two stages. Fistula maturation rates and mean time to initiation of fistula use were compared. Intensity of percutaneous interventions (including angioplasty, stenting and thrombectomy) was compared as interventions/patient-year of dialysis (PYD); secondary patency rates were compared from time of first intervention with the Kaplan Meier method. Results More women than men required BVT creation in 2 stages (62% vs 32%). Maturation rates (inclusive of fistulae needing percutaneous angioplasty to assist maturation) were 55/61 (90%) among 1-stage BVT, and 62/83 (75%) among 2-stage BVT (p = 0.02). Mean time to initiation of fistula use was 142 days among 1-stage BVT and 146 days among 2-stage BVT (p = 0.92). Intensity of percutaneous interventions was 1.84/PYD among 1-stage BVT and 2.15/PYD among 2-stage BVT. Secondary patency at 1, 2, 3 and 4 years for 1-stage BVT was 86±5.6, 75±9.1, 69±10.2 and 57±13%; secondary patency at 1, 2, 3 and 4 years for 2-stage BVT was 76±7.4, 71 ± 8.5, 49 ±14 and 25 ± 19 %, respectively (p=0.12). Conclusion Both forms of BVT were associated with high maturation rates, low intensity of interventions, and high secondary patency rates. When a basilic vein is small, BVT creation in two stages confers only a modest reduction in maturation and secondary patency outcomes; this access strategy should therefore be considered over a synthetic graft in patients not otherwise deemed suited to fistula creation.

A systematic review of preoperative duplex ultrasonography and arteriovenous fistula formation

Arteriovenous fistula (AVF) formation for dialysis access is a common procedure. Fistula maturation is unpredictable. Preoperative duplex mapping may increase procedural success. We undertook a systematic review to assess the effect of preoperative duplex mapping on subsequent AVF patency. The published literature was searched on PubMed and the Cochrane Library using the following keywords: 'arteriovenous fistula,' 'venous mapping,' 'ultrasound,' 'hemodialysis,' 'vascular access,' and 'perioperative vessel mapping.' Conference proceedings were hand searched for otherwise unpublished trials. Only randomized controlled trials in which preoperative duplex mapping was compared with clinical evaluation were eligible. Three trials (402 patients) were identified. More patients who underwent ultrasound successfully started using their fistula for dialysis access, although the difference did not reach statistical significance (174/214 vs 130/188; pooled odds ratio, 1.96; P = .11). Preoperative duplex mapping may improve fistula maturation rates. However, the results do not reach statistical significance and there are no cost-effectiveness data. Further work is required.

Editorial: The Issues Related to Hemodialysis Catheter Lock Prophylaxis with Recombinant Tissue Plasminogen Activator

Arteriovenous fistulas (AVF) are the most preferred and promoted form of dialysis access due to their lowest complication rates. However, the changing demographic profile of end- stage renal disease (ESRD) with an increasing elderly and diabetic population having relatively poor vasculature, relative lack of prudent pre-ESRD planning for AV fistula creation, late referrals, and comparatively lower fistula maturation rates, are essentially the factors accountable for our continued dependence upon central venous catheters (CVCs) [1-3]. Moreover, CVCs remain the only means to provide instant access to the circulation during emergency situations arising from the unpredictable course of chronic kidney disease. Virchow's described three broad categories of factors that contribute to thrombus formation -hypercoagulability, stasis and vascular endothelial injury. The placement of this relatively large foreign body traumatizes the host vessel and significantly alters hemodynamics fulfilling Virchow’s triad for thrombus formation and provides a nidus for bacterial entry into the circulation. However, catheter malfunction limits the life span of CVCs. Inadequate blood flow and catheter-related bloodstream infections (CRBSI) are common causes of recurrent use of thrombolytic therapy, antibiotics and often result in catheter removal. Generally, standard heparin (5000 U/ mL) is used to lock the CVCs to maintain catheter patency during the interdialytic period. Locking with heparin however, does not prevent bacterial colonization and subsequent development of CRBSI. Moreover, in vitro studies have shown that heparin may induce biofilm formation [4]. Replacing heparin with recombinant tissue plasminogen activator (rt-PA) once a week, as a dialysis catheter locking solution significantly reduced the incidence of catheter malfunction and CRBSI in a well conducted multicenter, double-blind, randomized controlled trial from Canada by Hemmelgarn and colleagues [5]. The authors were able to decrease the rates of catheter malfunction by 50% and

Increasing the Proportion of Autologous Arteriovenous Fistulas Does Not Diminish Fistula Patency

Arteriovenous fistulas (AVF) constructed before and after initiating the kidney disease outcomes and quality initiative (KDOQI) guidelines were reviewed at a single academic center to identify decreased patency with use of potentially inferior vein conduits. Primary access procedures performed pre- and post-adoption of KDOQI guidelines were compared for the primary outcomes of maturation rate and primary patency and the secondary outcome of access utilization. The proportion of autologous AVFs created was higher post-KDOQI (73% vs 35%, P < .001), and an increased use of the basilic vein was observed (20% vs 2%, P < .05). The failure rate of fistula maturation was reduced post-KDOQI (24% vs 38%, P < .05); however, access utilization was also decreased (59% vs 75%, P < .001). Adherence to KDOQI guidelines for AVFs does not compromise fistula patency and increased use of the basilic vein may lead to superior fistula maturation rates. Early referral may result in lower fistula utilization rates, however.

Two-Stage Basilic Vein Transposition—A New Approach for Pediatric Dialysis Access

Conclusion: Rates of arteriovenous fistula (AVF) maturation and patency in pediatric patients are higher for two-stage basilic vein transposition (BVT) than for BVT performed in one stage. Summary: BVT can be performed as a one-stage or a two-stage procedure. Advantages of a two-stage procedure are potential maturation of smaller veins before the actual transposition, thereby potentially improving ultimate success of the transposition. The two-stage procedure is technically easier than a one-stage transposition but does involve two separate procedures. The authors sought to determine whether using two-stage BVTs in children improves fistula maturation rates, fistula use, and overall patency compared with one-stage BVTs, other types of AVFs, and AV grafts. The study took place at two tertiary care children's hospitals. Between 1997 and 2008, 31 patients underwent AV access creation. Forty-two access procedures were performed: 15 two-stage BVTs (36%), 13 one-stage BVTs (31%), 6 radiocephalic fistulas (14%), 3 brachiocephalic fistulas (7%), 1 brachiobrachial fistula (2%), and 4 AV grafts (10%). Average follow-up was 20.4 ± 3.2 months for two-stage BVT and 47.9 ± 4.1 months for other AVFs. All two-stage BVTs matured, but only 14 of 27 (52%) other AVFs matured (P = .001). More two-stage BVTs (87%) were used for dialysis than other AVFs (48%; P = .024). The fistula failure rate in the two-stage BVT was 7% compared with 59% for other AVFs (P = .001). The patency at 1-year was 91% for two-stage BVT vs 47% for other AVFs (P = .003). The size of the basilic vein increased from 0.3 ± 0.027 cm before the performance of the first stage of the BVT to 0.79 ± 0.08 cm after the first stage of the two-stage BVT. Of the 16 failures in the other AVF group, 11 were primary failures occurring before attempted access. One case of steal syndrome occurred in the two-stage BVT group. Comment: Establishing durable hemodialysis access is difficult in all patients and is particularly difficult in the pediatric population because of the overall small caliber of the vessels. Most of the patients in this study, however, were not small children but adolescents with reasonable size vessels to work with. It is therefore a bit unclear whether the apparent advantage of the two-stage BVT in these patients was due to converting a more difficult procedure to a less difficult procedure for performance by surgeons who do not perform large volumes of dialysis access surgery. Two-stage BVT requires two operations, but the first is a relatively small procedure. Given the big picture, there appears to be no great disadvantage to the two-stage procedure and there may be a significant advantage in pediatric patients. The authors' contention that two-stage BVT should be preferred hemodialysis access in the pediatric population deserves consideration.

Basilic Vein Transposition: What is the Optimal Technique?

Objectives To compare the outcome of the one-stage basilic vein transposition (BVT) fistula with a modified, two-stage technique. Design Retrospective case-controlled study, performed in an academic centre. Material A total of 173 candidates for BVT fistula (87 males, mean age 61 years). Methods In one-stage BVT, the basilic vein is mobilised through a single incision, placed inside an anterolateral arm tunnel and anastomosed with the brachial artery. In two-stage procedures, the fistula–arterial anastomosis is created first, followed by the second stage, after fistula maturation several weeks later, when the basilic vein is mobilised through two skip incisions, transected near the anastomosis, placed inside an anterolateral arm tunnel and reanastomosed. Morbidity and fistula maturation rate were the main outcome measures. Results In one-stage BVT ( n = 76), the incidence of venous hypertension, wound haematomas and all complications (17%, 13% and 43%, respectively) was significantly higher than in two-stage procedures ( n = 98) (4%, p = 0.004, 3%, p = 0.012 and 11%, p < 0.001, respectively). Time (68 days) to fistula use was significantly decreased in one-stage BVT than in two-stage procedures (132 days, p < 0.001) but failure to mature rate was equivalent (15% vs. 18%, p = 0.49). Conclusions Our results indicate that the two-stage BVT fistula through two skip-arm incisions is superior to the established one-stage procedure in terms of less morbidity but at the cost of a second operation and longer time to access use. Further research comparing these two techniques is necessary. Until this issue is resolved, an individualised approach is suggested.