Native Fistula Research Articles

Frailty at the beginning of dialysis; is it a prognostic factor?

Introduction: Frailty (F) refers to the cumulative organic damage caused by aging, as a consequence of a diminished physiological reserve. Frailty’s prevalence is 73% in dialysis. Objectives: Our aim was to identify the prevalence of F in patients starting hemodialysis (HD) or hemodiafiltration online (HDF) treatment. To asses change in frailty during a six-month period of dialysis. Patients and Methods: This prospective cohort study evaluated 67 incident patient starting-HD or HDF at one year, with a follow-up period of at least six months. The frailty was assessed by the Fried frailty method. According to this test, we divided the population in two groups: Pre-frail (0-2) and frail (3-5). Results: Mean age was 64 years, 64% were male and 92% were treated with HD. A total of 35.8% of the patients were admitted to dialysis with a prosthetic or native fistula. The prevalence of F at the beginning of dialysis was 65.7%. The mean value of Charlson index (CHI) was 5.2 ± 2. There was a significant correlation between CHI and frailty test (P<0.0001). Basal F score (n=67) improved after 6 month (n=52): 3 (2-4) versus1 (1-2) (P<0.0001). Hematocrit (28 versus 32% P=0.05) and calcium levels (8.6 and 8.9 mg/dL, P<0.002) also increased after sixth-month. Global mortality was 7.5%. In the multivariate analysis CHI (P<0.001) and albumin (P=0.003) were frailty predictors. Conclusion: The prevalence of F in patients who start dialysis therapy is high. There was an improvement in F score after six-month of dialysis treatment. Patients with higher F score had higher mortality with higher CHI.

Abstract No. 67 Spontaneous and assisted recanalization of hemodialysis access after prior failed thrombectomy and abandonment: the Lazarus phenomenon

To evaluate the occurrence of spontaneous and assisted recanalization of hemodialysis accesses following failed percutaneous mechanical thrombectomy and abandonment of the access A retrospective review was performed of a prospectively managed quality assurance database of all hemodialysis (HD) access interventions performed between March 2001 and September 2020. Of 11,266 hemodialysis access interventions, 3,137 thrombectomy procedures were performed. Successful thrombectomy procedures were performed in 2,891 cases for an overall success rate of 92.2%. A total of 246 failed thrombectomy procedures were identified. An access was considered abandoned if no further attempts at thrombectomy were planned. Cases in which thrombectomy was recorded as failure due to other issues such as procedure complication but not considered abandoned, with planned subsequent return for repeat attempt, were excluded from analysis. Retrospective review of all failed thrombectomy procedures was performed to evaluate for a subset of accesses deemed abandoned that demonstrated spontaneous or assisted recanalization. Of the 246 failed mechanical thrombectomy procedures, access types included 99 native fistulas, 120 grafts, 9 hybrid access, and 18 without documented access details. There were 14 accesses (5.7% of failures) that demonstrated recanalization enabling subsequent salvage of the access after failed thrombectomy and access abandonment; all accesses exhibited trace flow beyond the (arterial) anastomosis at the time of failed thrombectomy. Of these salvaged accesses, 9 occurred in fistulas, 4 in grafts, and 1 in a hybrid access. Secondary procedures were performed in 7 patients including repeat thrombectomy with angioplasty (n = 3), thrombectomy with stent (n = 1), angioplasty (n = 1) and stent (n = 1) to maintain access function. Seven of the cases demonstrated spontaneous recanalization with no required additional intervention. All 14 salvaged accesses were successfully used for hemodialysis within 30 days post spontaneous or assisted recanalization. Spontaneous recanalization of clotted hemodialysis accesses considered abandoned after failed mechanical thrombectomy can occur. Further characterization of this phenomenon is needed to determine whether an observation period of catheter HD is warranted in the subset of patients with trace flow beyond the anastomosis following failed thrombectomy.

Multifrequency Bioimpedance Phase Angle as a Tool to Predict Maturation Failure of Native Fistulae for Hemodialysis

Background and objectives: An arteriovenous fistula is considered to be an ideal vascular access for patients receiving hemodialysis, its main limitation is its high failure rate to achieve maturation and long-term functionality loss. Multiple strategies have attempted to identify patients at risk. Bioelectrical impedance has shown to be a valuable resource in the determination of the hydration status, and the measurement of the phase angle through this method has demonstrated to be a good indicator of the nutritional state and it’s related as a general marker of survival. The objective of this study is to analyze the role of plasma albumin and phase angle measured through bioelectrical impedance as tools useful for predicting failure of arteriovenous fistulas.

Proximal Arteriovenous Fistulas in Hemodialysis Patients: Advantages and Disadvantages.

Introduction: The main objective of the present study is to investigate the advantages and disadvantages of proximal arteriovenous native fistulas. Hemodialysis is indispensable for patients with end-stage renal disease. For this purpose, arteriovenous fistulas (AVFs) are used. Among the native fistulas, distal radiocephalic AVF is the most preferred. However, brachiocephalic AVF (BCAVF) and brachiobasilic AVF with basilic vein transposition (basilic vein transposition arteriovenous fistula [BVTAVF]) can be used for a long time in dialysis patients whose distal vascular bed is depleted.Methods: This is a retrospective study of 117 AVFs (BCAVF and BVTAVF), in patients with end-stage chronic renal disease, that were opened with a surgical technique (2012-2018). The postoperative two-year patency rates, AVF locations, complications, and the advantages and disadvantages of these fistulas are reviewed and recorded in the light of the literature.Results: The mean age of the patients (52 men and 65 women) was 60.6 ± 13.6 years. The percentages of primary patency rates at 3, 6, 9, 12, and 24 months were 96.6%, 93.1%, 92%, 87.4%, and 82.8% in BCAVF patients, and 96.7%, 93.3%, 90%, 86.7%, and 80% in BVTAVF patients, respectively. The percentages of secondary patency rates at 6, 12, and 24 months were 100%, 93.3%, and 86.7% in BCAVF patients, and 100%, 100% and 87.7% in BVTAVF patients, respectively. Fistula thrombosis was seen as the most common complication. The early complication was bleeding/hematoma. As late complications, we encountered steal syndrome, ischemic pain in the relevant extremity, pseudoaneurysm, and high-output heart failure.Conclusion: Proximal AVFs are preferable fistulas with early maturation and high primary patency rates. We believe that relatively high complications can be avoided by opening fistulas with an appropriate surgical technique.

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<0.001), blood pump speed (291±49 vs 313±34, p<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<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<0,001), and higher weekly iron supplement dosing (60±61 vs 41±54mg/week, p<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.

New Onset Viral COVID19 Infection in Two End Stage Renal Disease Patients on Extracorporeal Hemodialysis Treatment

The first patient is a 62-years-old Caucasian male, affected by adult polycystic kidney disease in extracorporeal hemodialysis through an arterio-venous native fistula. The subject had presented fever for about a month and a half before being admitted.

Stima della portata della fistola artero-venosa mediante termodiluizione nei pazienti in emodialisi cronica: esperienza monocentrica.

Purpose: Vascular access surveillance in hemodialysis is today an important challenge for nephrologist. Low blood flow is a risk factor for development of thrombosis of native fistula or graft.
 The aim of the study is to evaluate the correspondence between flow measurement by thermodilution and Color Doppler, and to identify flow rate values using the Blood temperature monitor (BTM) method in the case of stenosis.
 Methods: We evaluated 29 patients on chronic hemodialysis. The evaluation of blood flow with BTM were performed during the first hour of the hemodialysis session. All patients underwent a color doppler of vascular access within 10 days from the BTM measurements.
 Results: The mean vascular access flow calculated with BTM resulted 1142 ± 700 ml/min and there was a correlation with color doppler data 1199 ± 644 ml/min (p=0,0001 r=0,829). The flow of patients with hemodynamically significant stenosis was 332 ± 92 ml/min with a minimum value of 270 ml/min and a maximum value of 440 ml/min.
 Conclusion: the correspondence between thermodilution and color doppler support the implementation of intradialitic evaluation of the vascular access blood flow with the BTM method. Thermodilution allows to identify earlier patients with high risk of vascular access failure and the need for further diagnostic and therapeutic investigations.

SUN-278 EFFECT OF NATIVE VASCULAR ACCESS FLOW ON 3-YEARS PATIENT SURVIVAL IN HEMODIALYSIS PATIENTS

Vascular access has paramount importance in hemodialysis (HD) patients. However it is also associated with many complications such as aneurysm, thrombosis, infection and congestive cardiac failure. This study is aimed to look at impact of vascular access flow on patient survival in HD patients and its contributing associated factors. A prospective cohort observational study were conducted in hemodialysis unit of Hospital Tuanku Jaafar, Seremban, Malaysia from March 2016 to March 2019.A total of 68 patients were recruited. Inclusion criteria were: age > 18 years old and been on HD at least 3 months using a native fistula. Patients who had to switch to vascular catheter temporarily for various reasons more than 3 months were excluded. Recruited patients were categorized on 3 groups based on their vascular access flow (Qa): Group 1 (<1000ml/min), Group 2 (Qa 1001-1500 ml/min) and Group 3 (Qa >1501ml/min). Demographic data and biochemical results were documented. The Univariate Cox Hazard Regression analyses were conducted for all possible predictor factors of survival(access flow volume, haemoglobin, calcium, phosphate, albumin, iPTH, CRP, diabetes, kT/V, BCM and ejection fraction (EF)based on Echocardiography). Baseline patient characteristics and biochemical results between the 3 groups did not vary significantly. The overall median survival time was 18 months. 3-year patient survival was 45% vs 22.6% vs 34% in Group 1, 2 and 3 respectively. None of the factors (access flow volume, haemoglobin, calcium, phosphate, albumin, iPTH, CRP, diabetes, kT/V, BCM and EF) were found to be significant in predicting patient survival. However it was noted patients with lower phosphate level (1.44 mmol/l vs. 2.28. mmol/l, p= 0.7), lower iPTH (321 pg/ml vs 369 pg/ml, p =0.5) and higher kT/V level (1.9 vs. 1.76, p=0.96) lives longer though statistically not significant. Our study showed that patients with access flow of less than 1000mls/min has better patient survival compared to above 1000 mls/min. Lower phosphate, lower iPTH and kT/V> 1.7 were associated with better patient survival.

SAT-252 The association of genotype polymorphisms of endothelial function-related genes with restenosis of arteriovenous access after angioplasty in hemodialysis patients

Venous intimal hyperplasia is more aggressive than arterial intimal hyperplasia after angioplasty. Veins tend to produce less nitric oxide, which could predispose to endothelial dysfunction. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase and contributes to vascular disease. In human, dimethylarginine dimethylaminohydrolase 1 (DDAH1) is the major enzyme degrading ADMA. We aimed to determine whether venous intimal hyperplasia in dialysis vascular access is influenced by common polymorphisms in the DDAH1 genes. This is a prospective observational cohort study. A total of 473 hemodialysis patients referred for angioplasty of hemodialysis vascular accesses were enrolled. There were 190 grafts and 283 native fistulas. Follow-up lasted for two years after interventions. Seven single nucleotide polymorphisms in DDAH1 were genotyped and ADMA were measured at baseline. Primary outcome was restenosis after angioplasty. Among the seven single nucleotide polymorphisms, plasma ADMA levels were significantly different in DDAH1 rs233112 (GA+GG vs. AA, 0.86 ± 0.23 vs. 0.82 ± 0.19μM, P=0.03) and rs1498373 (CT+TT vs. CC, 0.87 ± 0.23 vs. 0.82 ± 0.20 μM, P=0.02) genotypes. The native-access group with GG+GA genotype of rs233112 and CT+TT genotype of rs1498373 had higher risks of early restenosis at 3 months. In graft-access groups, only GG+GA genotype of rs233112 was associated with early restenosis. Combined analysis of graft- and native- access groups showed that patients with rs233112 GA+GG genotype and rs1498373 CT+TT genotype had higher risks of early restenosis (both p <0.001). In the multivariate analysis, the association of these genotypes with early restenosis is independent of clinical, access or biochemical Our findings suggest that certain DDAH1 polymorphisms modulate circulating ADMA levels and are associated with venous intimal hyperplasia.

Correlation Between Hand Ischemia Questionnaire and Peak Systolic Velocity of Radial Artery and Ulnar Artery in Hemodialysis Patients with Upper Arm Native Fistula Arteriovenosa

Introduction: Steal syndrome that occurs due to vascular access is one of the most feared complications after making a fistula arteriovenous (FAV). It is necessary to develop an assessment for early detection. Hand ischemia questionnaire (HIQ) and measurement of peak systolic velocity (PSV) of the radial artery and the ulnar artery are a form of subjective and objective examinations used to detect steal syndrome. The aim is to determine the correlation between HIQ and PSV of the radial artery and ulnar artery in hemodialysis patients with upper arm’s native FAV to detect symptoms of steal syndrome. Method: This is a cross-sectional study conducted in Cipto Mangunkusumo National Hospital from March to May 2019. Patients undergoing hemodialysis using upper arm native access FAV with or without symptoms of ischemia in the hands were included. Patients were asked to fill HIQ by interview, and then continued with measurement of PSV of the radial arteries and distal ulnar arteries from the hands with FAV. Results: A total of 80 samples were taken with 43 were women (53.8%), and 37 were men (46.2%). About 91.2% of the samples were FAV at the brachiocephalic level. The median age of the samples was 53 years. From the total HIQ score obtained, the results were a minimum of 0, maximum of 70, and a median value of 3. PSV of radial artery were minimum of 20 cm/s, maximum of 79 cm/s, and median 40 cm/s. The minimum PSV of the ulnar artery was 16 cm/s, the maximum was 70 cm/s, and the median was 41 cm/s. There was a significant correlation between the hand ischemia questionnaire and the peak systolic velocity of the radial artery and the ulnar artery in patients with native upper arm FAV (p &lt;0.001), but after diagnostic testing, it was found that sensitivity was only 15% and specificity was 100%. Conclusion: There was a significant correlation between hand ischemia questionnaire and peak systolic velocity of the radial artery and ulnar artery in patients with upper arm native FAV, but due to the low sensitivity, the hand ischemia questionnaire cannot be used as an initial examination to detect steal syndrome in patients with no symptoms of hand ischemia. Keywords: steal syndrome, Peak Systolic Velocity, Hand Ischemia Questionnaire.

Fistuloplasty using a radiation-and-time-saving sheathless balloon catheter

Introduction:Sheath placement in dialysis access interventions is traditionally necessary to obtain imaging, guide percutaneous angioplasty, and evaluate results. The aim of this study was to assess the feasibility of performing sheathless Arterio-venous (AV) access interventions using a novel percutaneous angioplasty balloon catheter.Methods:Between May and September 2017, data on all dialysis access interventions using a novel percutaneous angioplasty balloon with a dedicated injection port were collected. All procedures were performed without a sheath. Success was established as no conversion to sheath placement. Demographic data, location of lesion, time to perform procedure, amount of contrast used, radiation exposure, and access complications were recorded. Ultrasound was used to evaluate access site complications.Results:Sheathless interventions were successful in 24 patients with the mean age of 62 years (29–94). There were 5 PTFE grafts and 19 native fistulas. Lesions were located anywhere from the arterial anastomosis to the cephalic arch. The average balloon size was 6 mm (5–7 mm), and the procedure time was 15.8 min (8–45 min). No access site complications were observed.Conclusion:Sheathless intervention is feasible with several potential advantages, including short procedure time, minimal contrast volume, and reduced radiation exposure. Finally, the lower profile at the access site may result in fewer complications.

Transposed Basilic Vein Fistula: A Credible Option.

Objective: Native fistula creation for hemodialysis in patients who have exhausted all their superficial veins presents a challenge to vascular practice. We review our experience in transposed basilic vein fistula (BVT) creation and its usage for hemodialysis.Materials and Methods: We analyzed the hospital operative registry from January 2009 till June 2012 to identify the total number of BVT created in our center. Medical records of all patients were traced, and patients were interviewed using a standard proforma. In our center, BVT is performed as a two-stage procedure. All patients were routinely assessed with duplex scan preoperatively and postoperatively.Results: Two hundred thirty-nine patients were recruited in the study. Of these patients, 50.6% were male and 49.4% were female. Mean age was 53.4 years. Of these patients, 81.2% had history of other previous fistula creation. Risk factors profile includes diabetes mellitus in 59.8%, hypertension in 86.2%, and smoking in 13.0%. Of these patients, 84.5% had no operative complication. Commonest complication was wound infection, 6.3%, followed by hemorrhage or hemotoma required surgical intervention, 5.9%, and pseudoaneurysm, 1.3%. Primary and secondary patencies were at 84.2% and 86.1% at 1 year and 67.7% and 70.5% at 3 years, respectively.Conclusion: BVT is a credible option for challenging patients with absence of superficial veins for native fistula creation with good patency and low operative complication rate. Preoperative ultrasound assessment improves patient selection and outcome of BVT.

Efficacy of ProLumen in percutaneous thrombectomy of clotted dialysis access: a single-center prospective study.

To prospectively evaluate the efficacy of the ProLumen thrombectomy device for declot of dialysis access. 16 women and 4 men suffering from end-stage renal disease (ESRD) dependent on hemodialysis (mean age, 66.4 years) and presenting with thrombosed dialysis access were enrolled form October 2005 through February 2006. Sixteen patients had synthetic grafts and 4 had native fistulas. Mean age of access was 24.65 months (range, 2 to 96 months). A history of previous intervention was noted for seven patients (6 percutaneous, 1 surgical). A mean of 2.7 passes of the ProLumen device were required for the venous limb (range, 1 to 6) and 2.35 passes for the arterial limb (range, 0 to 5). Average procedure time was 48 minutes (range 32-81 minutes). Adjunctive thrombectomy devices were utilized in 5 cases. Good angiographic and clinical results were reported in 19 patients; one patient had a poor result. Dialysis flow rate prior to thrombosis was 425 mL/min (range, 300 to 550). The mean post-thrombectomy flow rate was 380 mL/min (range, 200 to 480; n=19). "Ease of use" of Pro Lumen thrombectomy device was rated good in 17 patients. Maneuverability was good in 14 patients and clot removal around the opposite sheath was rated as good in 18 patients. ProLumen is effective in thrombectomy of dialysis access. The device is easy to use, and effectively removes clot around the opposite sheath.

No association between hyperhomocysteinemia and vascular access thrombosis in chronic hemodialysis.

PURPOSE. Hyperhomocysteinemia, recognized as a risk factor for cardiovascular diseases, has also been related with controversy to vascular access thrombosis in hemodialysis. Our objective was to determine if such an association could be found in our hemodialysis population. METHODS. The survey was conducted in a cohort of 165 chronic hemodialysis patients. Their vascular access history was considered from hemodialysis initiation until November 1999, including the number of vascular accesses created (either native or synthetic fistulae), focussing on vascular access thrombotic events, and excluding primary vascular access dysfunction. Diabetes, hemoglobin, erythropoietin dose, anticoagulation, and methyltetrahydrofolate reductase (MTHFR) status were considered. Serum total homocysteine (tHcy) measures were sampled for all patients in June 1998 and repeated yearly. Patients had not been supplemented routinely with hydrosoluble vitamins until June 1998, after which all received DiaVite (R&D Laboratories, CA, USA) daily. RESULTS. Median survival of native fistulae was significantly longer (81 months, 95%CI 35-127) than for synthetic fistulae (31 months, 95%CI 27-51). Median vascular access survival was reduced for diabetics vs non diabetics (28 vs 57 months) (p<0.05), whereas sex, age and smoking had no impact. No correlation was found between tHcy concentration and the number of vascular access thrombotic events; homozygotes for MTHFR had higher tHcy but no more vascular access thrombotic events. The 38 patients with a mean vascular access survival of less than 12 months (63 months) were compared to the 127 patients with a mean vascular access survival of >= 12 months (3925 months) (p<0.05): no difference in their respective tHcy concentrations before and after DiaVite introduction was found (3113 and 208 vs 3417 and 226 mol/L), but the first group presented more numerous synthetic fistulae (p<0.0001), lower hemoglobin levels, and higher erythropoietin doses. CONCLUSIONS. No significant association between hyperhomocysteinemia and vascular access thrombosis could be found in our population. DiaVite introduction allowed a significant reduction in tHcy, but had no impact on vascular access survival, except for a slight but not significant reduction in the prevalence of vascular access thrombotic events during the year on DiaVite. Potential benefits of approaches to reduce tHcy for vascular access time-life prolongation remain to be demonstrated.

Management of infected brachial-axillary prosthesis for hemodialysis: Report of three cases

Brachial-axillary bridge graft is an alternative to native fistula in the absence of vein access or defect of maturation. Infection of the prosthetic graft is a serious complication. It is a relatively common complication and is the second leading cause of graft loss. It should be prevented by the adoption of extreme rigor concerning monitoring of access, their care and punctures. We report three cases with different aspect clinic and therapeutic of infected brachial-axillary prosthesis for hemodialysis.

Endovascular Covered Stenting to Treat an Arteriovenous Graft to Native Vein Fistula, Caused by Dialysis Needle Cannulation

Endovascular Covered Stenting to Treat an Arteriovenous Graft to Native Vein Fistula, Caused by Dialysis Needle Cannulation

Cryopreserved venous allograft is an acceptable conduit in patients with current or prior angioaccess graft infection

ObjectiveThe durability of cryopreserved allograft has been previously demonstrated in the setting of infection. The objective of this study was to examine the safety, efficacy, patency, and cost per day of graft patency associated with using cryopreserved allograft (vein and artery) for hemodialysis access in patients with no autogenous tissue for native fistula creation and with arteriovenous graft infection or in patients at high risk for infection. MethodsPatients implanted with cryopreserved allograft for hemodialysis access between January 2004 and January 2014 were reviewed using a standardized, multi-institutional database that evaluated demographic, comorbidity, procedural, and outcomes data. ResultsThere were 457 patients who underwent placement of cryopreserved vein (femoral: n = 337, saphenous: n = 11) or artery (femoral: n = 109) for hemodialysis access at 20 hospitals. Primary indications for allograft use included high risk of infection in 191 patients (42%), history of infected prosthetic graft in 169 (37%), and current infection in 97 (21%). Grafts were placed more frequently in the arm (78%) than in the groin, with no difference in allograft conduit used. Mean time from placement to first hemodialysis use was 46 days (median, 34 days). Duration of functional graft use was 40 ± 7 months for cryopreserved vein and 21 ± 8 months for cryopreserved artery (P < .05), and mean number of procedures required to maintain patency at follow-up of 58 ± 21 months was 1.6 for artery and 0.9 for vein (P < .05). Local access complications occurred in 32% of patients and included late thrombosis (14%), graft stenosis (9%), late infection (9%), arteriovenous access malfunction (7%), early thrombosis (3%), and early infection (3%). Early and late infections both occurred more frequently in the groin (P = .030, P = .017, respectively), and late thrombosis occurred more frequently with cryopreserved artery (P < .001). Of the 82 patients (18%) in whom the cryopreserved allograft was placed in the same location as the excised infected prosthetic graft, 13 had infection of the allograft during the study period (early: n = 4; late: n = 9), with no significant difference in infection rate (P = .312) compared with the remainder of the study population. The 1-, 3-, and 5-year primary patency was 58%, 35%, and 17% for cryopreserved femoral vein and 49%, 17%, and 8% for artery, respectively (P < .001). Secondary patency at 1, 3, and 5 years was 90%, 78%, and 58% for cryopreserved femoral vein and 75%, 53%, and 42% for artery, respectively (P < .001). Mean allograft fee per day of graft patency was $4.78 for cryopreserved vein and $6.97 for artery (P < .05), excluding interventional costs to maintain patency. ConclusionsCryopreserved allograft provides an excellent conduit for angioaccess when autogenous tissue is not available in patients with current or past conduit infection. Cryopreserved vein was associated with higher patency and a lower cost per day of graft patency. Cryopreserved allograft allows for immediate reconstruction through areas of infection, reduces the need for staged procedures, and allows early use for dialysis.

Are Non-Newtonian Effects Important in Hemodynamic Simulations of Patients With Autogenous Fistula?

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practice, namely Quemada and Casson. Because of the specific interest in neointimal hyperplasia and the onset of stenosis in this study, particular attention is placed on differences in nonhomeostatic wall shear stress (WSS) as that drives the venous adaptation process that leads to venous geometric evolution over time in ESRD patients. Surprisingly, the CFD results exhibit no major differences in the flow field and general flow characteristics of a non-Newtonian simulation and a corresponding identical Newtonian counterpart. It is found that the vein's geometric features and the dialysis-induced flow rate have far greater influence on the WSS distribution within the numerical domain.

Dialysis Catheter Placement in Patients With Exhausted Access

Patients with end-stage renal disease undergo renal transplant, peritoneal dialysis, or intermittent hemodialysis for renal replacement therapy. For hemodialysis, native fistulas or grafts are preferred but hemodialysis catheters are often necessary. Per KDOQI, the right jugular vein is the preferred vessel of access for these catheters. However, in patients with long-standing end-stage renal disease vein thrombosis, stenosis and occlusion occurs. In these patients with end-stage vascular access, unconventional routes of placement of dialysis catheters are needed. These methods include placing them by means of sharp recanalization, via a translumbar route directly into the inferior vena cava, and via transhepatic and transrenal routes. These difficult, but potentially lifesaving methods of gaining vascular access are reviewed in this article.

Vertebral and internal mammary artery steal syndrome in patients with hemodialysis access.

Increased flow in the subclavian artery feeding a vascular access for hemodialysis can induce steal phenomena in the vertebral (VA) and internal mammary artery (IMA). The aim of this study was to describe the hemodynamic effects of access flow on the VA and IMA in patients with native fistulas and grafts. Peak systolic (PSV) and end diastolic (EDV) velocity measurements of the VA, IMA and carotid arteries, as well as flow volume measurements of the subclavian artery, were performed. Flow measurements at the side of the vascular access were compared with the contralateral side. Fifty-five patients were consecutively included, most with a radio-cephalic fistula on the left arm with a mean shunt volume of 1156 ml/min. Pathologic flow patterns were observed in the ipsilateral VA in four patients (7.3 %); contralateral VA flow was normal in all patients. Peak systolic velocity of the VA was significantly decreased at the side of the shunt arm with a PSV of 42.6 ± 11.8 cm/s compared to 48.4 ± 15.6 cm/s contralateral (p < 0.05). The IMA flow pattern were normal in all patients. The PSV of the IMA was significantly decreased (p < 0.01) at the side of the shunt arm (87.5 ± 29.1 cm/s) compared to the non-shunt arm (95.9 ± 27.4 cm/s). We describe significant hemodynamic effects of fistulas to the vertebral and internal mammary arteries. Doppler spectral analysis of the vertebral and internal mammary arteries should be integrated in ultrasound, especially in patients with cerebrovascular or cardiac symptoms.