Peptide-coated vascular grafts: An in vivo study in sheep

The data on function and patency of prosthetic vascular grafts in various clinical settings are limited. The purpose of this in vivo study was to compare the function and patency of P15‐coated expanded polytetrafluoroethylene (ePTFE) vascular grafts to uncoated ePTFE grafts in sheep. The P15 cell‐binding peptide was covalently immobilized onto the surface of ePTFE grafts by a novel atmospheric plasma coating method. We evaluated the amount of neointimal tissue ingrowth present at the arterial and venous sides of the anastomoses and the degree of endothelial cell resurfacing of the luminal surface of the graft. Four P15‐coated grafts and two control grafts were implanted as arteriovenous grafts between the femoral artery and vein and the carotid artery and jugular vein in two sheep (n = 6). One animal was euthanized after 14 days and the other after 28 days. The study showed the intimal ingrowth was significantly less. The average intimal thickness of P15‐coated grafts (658 µm) was approximately two and a half times less than that of uncoated samples (1657 µm). The newly formed endothelial cell lining was thicker and its coverage was more uniform for P15‐coated grafts compared to the uncoated controls.     

Radio‐cephalic fistula recovered with drainage to forearm basilic vein

Dysfunction problems with vascular access are a concern to patients and dialysis units. The vascular surgeon should analyse such dysfunction and perform a careful assessment of the vascular network in order to find new fistula layouts. We introduce and discuss the case of creation of a radio‐cephalic fistula with outflow into the forearm basilic vein through rotation of the forearm basilic vein toward the cephalic vein in the forearm of an 88‐year‐old hemodialysis male patient. This technique enables extending fistula patency and improves cost efficiency.     

Treatment of symptomatic coronary artery disease in patients with end‐stage renal disease on hemodialysis with paclitaxel‐eluting TAXUS stent

Percutaneous coronary intervention (PCI) utilizing drug‐eluting stents is becoming a very common revascularization technique in the dialysis cohort; therefore, we sought to identify the impact of dialysis on outcomes in this group of patients. This is a multicenter registry comparing results of 290 patients (186 with normal kidney function, 104 on dialysis) who underwent PCI with exclusive use of paclitaxel‐eluting TAXUS stent. The primary endpoint was an assessment of major adverse cardiac events (MACE) at 1‐ and 2‐year observation. Mean follow‐up was 23.3 ± 6.1 months. Results at 12 months showed: MACE 11.8% vs. 7.7% (P = not significant [ns]), composite major adverse cardiac and cerebrovascular events (MACCE) 12.4% vs. 11.5% (P = ns), all‐cause death 2.7% vs. 8.6% (P < 0.05), cardiac death 2.7% vs. 1.9% (P = ns), target vessel revascularization (TVR) 9.1% vs. 6.7% (P = ns), acute myocardial infarction (AMI) 3.8% vs. 2.9% (P = ns), cerebrovascular events (CVA) 0.5% vs. 1.0% (P = ns); and results at 24 months showed: MACE 17.7% vs. 18.3% (P = ns), MACCE 21.5% vs. 26.0% (P = ns), all‐cause death 4.3% vs. 14.4% (P < 0.01), cardiac death 3.2% vs. 1.9% (P = ns), TVR 14.0% vs. 16.3% (P = ns), AMI 5.4% vs. 5.8% (P = ns), CVA 3.2% vs. 2.9% (P = ns) for non–end‐stage renal disease (ESRD) and dialysis group, respectively. Prior coronary artery bypass graft (CABG) was found to be single risk factor for MACE, TVR, and MACCE in patients with ESRD, while dialysis and prior CABG were found to be single risk factors for death in the entire population. PCI with TAXUS is a feasible procedure and presents promising results in dialysis‐dependent patients.     

Efficacy of percutaneous angioplasty in non‐maturing Brescia‐Cimino fistulas

Purpose:  To evaluate efficacy of percutaneous transluminal angioplasty (PTA) in non‐maturing Brescia‐Cimino fistulas. Methods:  Between January 1997 and December 2003, we treated 22 patients with non‐maturing Brescia‐Cimino fistulas by PTA. Retrospective analysis was performed on the findings of fistulogram, techniques and success rate of PTA, and patency rate. Results:  Seventeen segmental stenoses and 5 segmental occlusions of cephalic veins were identified. Sixteen stenoses and 2 occlusions were located at the cephalic vein adjacent to the anastomosis site, and 3 occlusions and 1 stenosis were seen at the proximal vein near the elbow joint. In addition to venous stenosis, a focal arterial stenosis at the anastomosis site and two accompanying accessory veins that might hamper maturation of main cephalic vein was seen in each of two patients, respectively. Simultaneous occlusion of left innominate vein as well as occlusion of cephalic vein were noted in one patient. Initial success rate of PTA was 95.5%(21/22). Overall success rate including 11 additional PTAs performed during follow‐up was 96.9%(32/33). No major complication occurred. Primary and secondary patency rates were 72% and 95% at 3 months, and 50% and 77% at 6 months, respectively. Conclusion:  PTA is an effective and safe method in salvaging non‐maturing Brescia‐Cimino fistulas.     

Dialysis access venous stenosis: Treatment with balloon angioplasty 30‐second vs. 1‐minute inflation times

Percutaneous balloon angioplasty is the standard of care in the endovascular treatment of dialysis access venous stenosis. The significance of balloon inflation times in the treatment of these stenoses is not well defined. Our objective was to examine the outcomes of 30‐second vs. 1‐minute balloon inflation times on primary‐assisted patency of arteriovenous fistulae and grafts. Using a prospectively collected vascular access database, we identified a total of 75 patients referred for access dysfunction during a 5‐year period. These patients received 223 interventions (178 with 30‐second inflations and 45 with 1‐minute inflations). We compared primary‐assisted patency during the subsequent 9 months across groups defined by inflation times. Demographics and baseline characteristics were similar across groups. Immediate technical success and patency in the first 3 months were similar across groups (hazard ratio [HR] = 0.86; 95% confidence interval [CI]: 0.34–2.20). After 3 months, however, a 1‐minute inflation time was associated with greater incidence of access failure (adjusted HR [aHR] = 1.74; 95% CI: 1.09–2.79). Other predictors of access failure included age over 60 (aHR = 1.02; 95% CI: 1.01–1.04), central location of the lesion (aHR = 2.49; CI: 1.27–4.89), and three or more prior procedures (aHR 2.48; CI: 1.19–5.16). Our data suggest that shorter balloon inflation times may be associated with improved longer term access patency, although the benefit was not observed until after 3 months. Given the increasing demands of maintaining access patency in the era of the National Kidney Foundation Kidney Disease Outcomes Quality Initiative and Fistula First, the role of angioplasty times requires further study.     

The effect of statin therapy on the formation of arteriovenous fistula stenoses and the rate of reoccurrence of previously treated stenoses

Statins reduce inflammation in end‐stage renal disease patients and improve endothelial function beyond cholesterol lowering. Despite this, statins do not improve the maturation rate, primary patency rate, and the cumulative survival of arteriovenous fistulas (AVFs). It is unknown if statins decrease the number of stenoses developing in AVFs or prolong the intervals between angioplasties needed to treat recurring stenoses. We conducted a retrospective chart review of our 265 active dialysis patients. The statin group was significantly more likely to be diabetic (64% vs. 43.6%) and treated with aspirin (64% vs. 40%) when compared to those not treated with statins (P = 0.04 and 0.01). The mean time to first intervention (primary patency) was 16.5 months in statin users and 15.8 months in the nonstatin group (P = 0.49) with standard deviations of ±18.5 and 16.6 months, respectively. Statin use was not associated with a significant decrease in the number of stenoses diagnosed (P = 0.28). The mean time between recurrent stenoses’ angioplasties was 8.9 months in statin users and 7.3 months in the nonstatin patients (P = 0.25). Aspirin users were more likely to have a decreased primary patency (rate ratio = 1.65, P = 0.03) compared with nonaspirin users. Patients who were prescribed aspirin developed 1.6 (P 0.01) times more stenoses than those not treated with aspirin. We report for the first time that statin therapy does not decrease the number of stenotic lesions developing in the AVF or prolong the interval between procedures required to treat recurrent stenoses.     

Use of the subcutaneous venous network of the forearm to create an arteriovenous fistula

The reconstruction of vascular access in patients with kidney allograft failure is a challenging problem. A case of a 62‐year‐old man with transplanted kidney insufficiency is described. The patient was initially dialyzed with a wrist radial‐cephalic arteriovenous fistula. In the post‐transplantation period, the enormously dilated venous part of the anastomosis was ligated and the part of the vein suspected of being the source of bacteremia was excised. The man was referred to our department due to kidney allograft failure for vascular access creation. During preoperative assessment, we unexpectedly found a soft thrill on the forearm. Doppler ultrasound confirmed fistula patency, although the blood supply was not sufficient to perform dialysis. Angiography showed the blood flow from the radial artery to the cephalic vein, through a complicated vessel system consisting of inter alia a dilated vein of the subcutaneous venous network. We successfully used this vein as the vascular access outflow for fistula recreation. In conclusion, making use of veins of the subcutaneous venous network of the forearm for creation of a native fistula should be considered in selected cases.     

The effect of in-stent restenosis on hemodialysis access patency

Endovascular stents have recently been shown to extend access patency in thrombosed and stenotic arteriovenous grafts (AVG). Concern remains over the frequency and severity of in-stent restenosis, though this has not been rigorously defined to date. The study was a retrospective analysis of hemodialysis patients referred for access dysfunction during a 2-year period. Using a prospectively collected, vascular access database, we identified 76 patients seen for follow-up angiography due to access dysfunction after stent placement. We compared the effect of in-stent restenosis vs. de novo lesions in patients with previously placed endovascular stents. Measured outcomes were primary assisted patency and frequency of in-stent and de novo lesions. Thirty-five (46.1%) patients had de novo lesions, while 41 (53.9%) had in-stent restenosis. In-stent restenosis was found to be the only factor associated with severity of luminal stenosis (β=0.35, 95% confidence interval 2.21–15.48, P=0.01). In-stent restenosis was associated with increased primary patency among AVGs (hazards ratio 3.10; 95% confidence interval 1.35–7.10; P=0.008). Primary patency of in-stent restenosis vs. de novo lesions for AVGs were respectively: 78% vs. 94% at 1 month, 56% vs. 42% at 3 months, 33% vs. 6% at 6 months. For arteriovenous fistulae, the difference in primary patency of in-stent vs. de novo lesions was not statistically significant. In-stent restenosis is associated with higher percent luminal diameter lesions, while de novo lesions rather than in-stent restenosis are associated with higher risk of AVG access failure and reduced primary patency.     

Arteriovenous fistula for the 80 years and older patients on hemodialysis: Is it worth it?

Over the last years, the proportion of patients older than 80 years with end‐stage renal disease has been constantly growing. Arteriovenous fistula (AVF) is known as the best vascular access for hemodialysis, but evidence for its added value is lacking for elderly. We retrospectively identified new vascular access (AVF and central venous catheter) created or installed between June 2005 and June 2008 in patients 80 years and older and in patients between 50 and 60 years. For every new AVF, we calculated primary failure, primary and secondary patency durations. Fifty‐five and 57 patients had a new vascular access in the >80 years old and 50 to 60 years old groups. Among these, 25 and 41 were new AVF in the older and younger groups. Primary failure was more frequent in elderly than in the younger (40% vs. 17%, P = 0.04). Primary patency was not significantly different in both groups (P = 0.06). Secondary patency was shorter in elderly (P = 0.005). Among the older group, the presence of an AVF was not associated with a difference in mortality (46% vs. 60%, P = 0.28), whereas there was a lower mortality in the younger group with AVF (12% vs. 43% P = 0.008). These results indicate lower patency duration in very elderly patients compared to middle‐aged patients. Without leading to the exclusion of patients over 80 years old for AVF creation, it might reinforce the need of a careful selection and evaluation in this population prior to referral.     

Long-term outcomes of transposed basilic vein arteriovenous fistulae

The need for reliable, long-term hemodialysis vascular access remains critical. To determine the long-term outcomes of transposed basilic vein arteriovenous fistulae (BVT) and their comparability with other vascular accesses, we determined retrospectively the primary and secondary patency rates in 58 BVT and in a total of 58 arteriovenous fistulae (AVF) and arteriovenous grafts (AVG) at a single center. Fifty-eight BVT were placed in 57 individuals, 69% after prior vascular access failure. Ten BVT failed before initial use and 2 patients expired with functioning accesses before dialysis initiation. In all 58 BVT, 46.8+/-10.8% functioned at 3 years, with median survival 30.8 months. Limiting analyses to the 46 BVT that were ultimately accessed, 3-year primary and secondary patency rates were 38.3+/-7.7% and 56.5+/-12.6%, respectively. Lower ejection fraction (p=0.054) and greater numbers of prior permanent dialysis catheters (p=0.005) were present in those with failed BVT. Compared with AVF, BVT had similar 3-year primary and secondary patency rates. The secondary patency rate was significantly better for BVT vs. AVG over the observation period; at 3 years, the rates were 56.5+/-12.6% vs. 9.1+/-6.0% (p=0.002), respectively. Basilic vein arteriovenous fistulae are valuable hemodialysis accesses. Although nearly 20% of newly placed BVT will not function before first use, those that are functional have median survivals exceeding 6 years, and 38% will not require intervention within 3 years of initial use.     

Heparin-modified small-diameter nanofibrous vascular grafts

Due to high incidence of vascular bypass procedures, an unmet need for suitable vessel replacements exists, especially for small-diameter vascular grafts. Here we produced 1-mm diameter vascular grafts with nanofibrous structure via electrospinning, and successfully modified the nanofibers by the conjugation of heparin using di-amino-poly(ethylene glycol) (PEG) as a linker. Antithrombogenic activity of these heparin-modified scaffolds was confirmed in vitro. After 1 month implantation using a rat common carotid artery bypass model, heparin-modified grafts exhibited 85.7% patency, versus 57.1% patency of PEGylated grafts and 42.9% patency of untreated grafts. Post-explant analysis of patent grafts showed complete endothelialization of the lumen and neovascularization around the graft. Smooth muscle cells were found in the surrounding neo-tissue. In addition, greater cell infiltration was observed in heparin-modified grafts. These findings suggest heparin modification may play multiple roles in the function and remodeling of nanofibrous vascular grafts, by preventing thrombosis and maintaining patency, and by promoting cell infiltration into the three-dimensional nanofibrous structure for remodeling.     

Association of coronary artery calcium score and vascular dysfunction in long‐term hemodialysis patients

Long‐term hemodialysis patients are prone to an exceptionally high burden of cardiovascular disease and mortality. The novel temperature‐based technology of digital thermal monitoring (DTM) of vascular reactivity appears associated with the severity of coronary artery disease in asymptomatic population. We hypothesized that in hemodialysis patients, the DTM and coronary artery calcium (CAC) score have a gradient association that follows that of subjects without kidney disease. We examined the cross‐sectional DTM‐CAC associations in a group of long‐term hemodialysis patients, and their 1:1 matched normal counterpart. Area under the curve for temperature (TMP‐AUC), the surrogate of the DTM index of vascular function, was assessed after a 5‐minute arm‐cuff reactive hyperemia test. Coronary calcium score was measured via electron beam computed tomography or multidetector computed tomography scan. We studied 105 randomly recruited hemodialysis patients (age: 58 ± 13 years, 47% men) and 105 age‐ and gender‐matched controls. In hemodialysis patients vs. controls, TMP‐AUC was significantly worse (114 ± 72 vs. 143 ± 80, P = 0.001) and CAC score was higher (525 ± 425 vs. 240 ± 332, P < 0.001). Hemodialysis patients were 14 times more likely to have CAC score >1000 as compared with controls. After adjustment for known confounders, the relative risk for case vs. control for each standard deviation decrease in TMP‐AUC was 1.46 (95% confidence interval: 1.12–1.93, P = 0.007). Vascular reactivity measured via the novel DTM technology is incrementally worse across CAC scores in hemodialysis patients, in whom both measures are even worse than their age‐ and gender‐matched controls. The DTM technology may offer a convenient and radiation‐free approach to risk‐stratify hemodialysis patients.     

Catheter‐related bacteremia and mortality in frequent nocturnal home hemodialysis

Frequent nightly home hemodialysis (NHHD) has emerged as an attractive alternative to thrice weekly in‐center hemodialysis, albeit with preponderant long‐term hemodialysis catheter used. Sixty‐three NHHD patients from University of Virginia Lynchburg Dialysis Facility were matched 1:2 with 121 conventional hemodialysis patients admitted to Fresenius Medical Care North America facilities from January 1, 2007 to December 31, 2010. Matching considered age (± 5 years), gender, race, dialysis vintage, and diabetes. The primary end‐point was the combined incidence of bacteremia/sepsis, for up to 20 months or upon changing to a fistula/graft (with catheter removal), transferring to peritoneal dialysis (PD), or at the time of kidney transplant or death. No significant differences were observed in rate of fistula/graft conversion, transfer to PD, transplant, or death between NHHD and in‐center hemodialysis (IHD) groups. For the first catheter used, the rate of catheter‐related sepsis was not significantly different between the NHHD (1.77 per 100 patient months) and IHD (2.03 per 100 patient months; P = 0.21). Combining all catheters, the rate of bacteremia/sepsis per 100 patient months in the NHHD group was 1.51 and in the IHD group was 2.01 (P = 0.35). Median catheter lifespan for the first catheter was 5.6 (1.7～19.0) for NHHD and 4.6 (2.7～7.8) for the IHD group (P = 0.64), and for all catheters used was 5.2 (Q1～Q3 = 1.5～15.2) months in NHHD group, and 4.1 (2.0～6.8) months in IHD group (P = 0.20). The rate of bacteremia and death is not different for up to 20 months in catheter users who dialyze via frequent NHHD vs. thrice weekly IHD.     

Arteriovenous fistula: end‐to‐end or end‐to side anastomosis?

The purpose of the present study was to compare the end‐to‐end (ETEa) with the end‐to‐side (ETSa) anastomosis in patients starting hemodialysis by means of radio‐cephalic artero‐venous fistulae (AVF). In our experience, we compared the results, as early failure (EF), late thrombosis (LT), stenosis, steal syndrome, and primary patency (PP), in 2 groups of hemodialysis incident patients that had been placed an AVF by means of ETEa or ETSa. The observation period lasted 24 months for each of the 2 types of AVF, starting from October 2005 to September 2007 for ETEa and from October 2007 to September 2009 for ETSa. One hundred forty patients were included in the present study. We have consecutively performed 99 AVF interventions at the wrist or at the third distal of the forearm, in 70 patients by means of ETEa and 82 AVF interventions in the same anatomical places in 70 patients by means of ETSa. The patients with ETEa had a mean age of 64.4 ± 14.6 years, males were 65.8% and the age dialysis at the end of observation was 10.4 ± 5.7 months. Those with ETSa had a mean age of 65.9 ± 15.5 years and the males were 62.9%, the age dialysis at the end of observation was 9.2 ± 5.5 months. The surgical team was composed by the same nephrologists. The statistical study was performed by means of the χ chi‐square and Fisher's exact test. We have observed more late thrombosis (10% vs. 4.1%) and stenosis (21.4% vs. 2.7%) in ETEa than in ETSa. The number of early thrombosis was similar in the 2 types of anastomosis. The primary patency 1‐year rate was better though not significantly in the ETS (80% vs. 85.7%) In our experience the ETSa provides, overall better results, both regarding the complications and primary survival than ETEa. For the benefits that seem to come from it, we believe, that a broad ETSa in the distal native AVF is preferable to the ETEa.     

Effect of high‐protein supplemental therapy on subjective global assessment of CKD‐5D patients

Adequate nutrition in patients on hemodialysis is an important step for improving the quality of life. This prospective study was undertaken to monitor the nutritional status of patients who were given high‐protein supplements on malnutrition inflammation score (MIS) and to correlate with biochemical parameters in maintenance hemodialysis (MHD) patients. This prospective study was conducted on 55 chronic kidney disease patients on MHD (37 women, 18 men), aged between 21 and 67 years. Of the 55 patients, 26 patients received high‐protein commercial nutritional supplements, whereas 29 patients received high‐protein kitchen feeding. Every patient had their MIS, 24‐hour dietary recall, hand grip, mid arm circumference, triceps skin‐fold thickness at 0, 3, and 6 months. Each of the above parameters was compared between the high‐protein commercial nutritional supplement cohort and high‐protein kitchen feeding cohort, and the data were analyzed. Of the 55 patients, 82.61% of patients on high‐protein kitchen feeding group and 66.67% in high‐protein commercial nutritional supplement group were nonvegetarian (P = 0.021). According to the MIS, improvement was observed in malnutrition status from 3‐ to 6‐month period in 38.1% of patients in high‐protein commercial supplement group, whereas only in 8.7% in high‐protein kitchen feeding group (P = 0.04). Assessment showed improvement in malnutrition status with high‐protein commercial nutritional supplement, which was marked in patients with age group >65 years (P = 0.03) and in those in whom serum albumin is <35 g/L (P = 0.02). Both high‐protein kitchen feeding and high‐protein commercial nutritional supplement cohorts were observed to have improvement in overall nutritional status. Older patients >65 years with lower serum albumin levels (<3.5 g/dL) were observed to have significant improvement in nutritional status with high‐protein commercial nutritional supplements.     

Morphometric and histological parameters in veins of diabetic patients undergoing brachiocephalic fistula placement

Diabetic patients with end‐stage renal failure have higher rates of arteriovenous failures when compared with nondiabetics. The aim was to compare differences in indicators of vascular remodeling and endothelial dysfunction in veins of patients with or without diabetes at the time of surgical placement. In this prospective observational trial, vein samples were collected from patients when a brachiocephalic fistula was created. Morphometric measurements and extent of fibrosis were determined using Image J software. Histological analysis, for the presence of myofibroblasts and level of endothelial nitric oxide synthase, was performed by immunohistochemical staining and scored in semi‐quantitative manner. Asymmetric dimethylarginine was determined at the time of access placement. Comparison of diabetics and nondiabetics was performed using Wilcoxon rank sum and Fisher's exact tests. Eighteen patients were included; 10 were diabetics. There was a significant difference in the measurement of vein area between groups, with diabetic vein samples having larger luminal area of average 832,001.18 μm² (317,582.17–3,695,670.36, P = 0.04). The maximal intimal to medial thickness ratio was higher in diabetic vein samples (0.71 vs. 0.24, P = 0.03) along with statistically significant higher maximal intimal thickness (312.12 vs. 115.14 μm, P = 0.03). There is a significant difference in vascular wall remodeling between diabetics and nondiabetics at the level of the cephalic vein at the time of brachiocephalic placement. The unexpected finding of significantly larger luminal area in diabetic veins could be a major factor positively affecting brachiocephalic outcomes in otherwise impaired remodeling in this patient population.     

Lower C‐reactive protein and better hemodialysis survival are associated with regular exercise activity: Longitudinal outcomes from the ACTIVE‐ADIPOSE special study

Introduction Cross‐sectional and longitudinal studies in the general population have shown that a physically active lifestyle may have anti‐inflammatory properties, but evidence from studies conducted with maintenance hemodialysis (HD) patients is limited. Methods A multicenter prospective cohort of 755 HD participants aged 20–92 was evaluated in a USRDS special study 2009–2013. Kilocalories/week (kcal/week) of leisure time physical activity (LTPA) was estimated from the Minnesota Leisure Time Activity questionnaire. Predialysis serum samples were obtained concurrent with LTPA report date. Generalized estimating equations (GEE) examined association of participants’ LTPA and log‐normalized CRP across 24 months. Cox proportional hazards models investigated LTPA and survival over a median follow‐up of 718 days. Findings Baseline median CRP concentration was lower for participants with 500+ kcal/week LTPA vs. those with <500 kcal/week LTPA (3.4 mg/L vs. 4.6 mg/L; P = 0.03). Participants who reported lower LTPA (<500 kcal/week) at both baseline and 12 months had a borderline significant increase in CRP concentration (within‐group change 4.8 [1.9–10.4] to 5.8 [1.6–15.7]; P = 0.08). Lower LTPA was associated with higher log CRP over 24 months in adjusted GEE analyses (β coefficient = 0.16 [95% CI 0.02–0.31]; P = 0.03). 67/364 (18%) and 43/391 (11%) deaths occurred, respectively, among participants reporting <500 vs. 500+ kcal/week LTPA [adjusted mortality hazard ratio 1.63 (CI, 1.07, 2.47)]. Discussion The data suggest that increased estimated levels of LTPA, a physical activity/exercise opportunity widely applicable to HD patients, may be associated with lower CRP concentration as well as better survival outcome.     

Can primary failure of arteriovenous fistulas be anticipated?

Primary failure, early thrombosis, and inadequate maturation are the main complications encountered in arteriovenous fistulas. Doppler ultrasonographic assessment of flow‐mediated dilatation (FMD) is currently used for the early diagnosis of atherosclerosis. Clinical experience in the use of FMD for preoperative assessment of vasculature is rather limited; therefore, we sought to elucidate the relationship between preoperative FMD and primary failure of the fistula. Thirty‐three patients with end‐stage renal disease who were admitted to our hospital between January and July 2005 were included in our study. Medical histories were established and the internal diameter, wall thickness, peak systolic flow rate, and resistive index (RI) were measured in the cephalic vein and radial and brachial arteries. Flow‐mediated dilatation and nitrate‐mediated dilatation (NMD) of the brachial artery were assessed. Fistulas were evaluated 48 hours and 30 days postoperatively. Brachial arterial internal diameter was lower in all fistulas that developed primary failure in 48 hours (0.4 ± 0.07 cm vs. 0.35 ± 0.07 cm, P = 0.016). The radial artery RI was found to be significantly elevated in fistulas with both early (48‐hour) and late‐term (30‐day) failure (0.9 ± 0.08 vs. 0.68 ± 0.3, P = 0.01, and 0.86 ± 0.8 vs. 0.67 ± 0.3, P = 0.038, respectively). The brachial artery peak systolic flow rate was significantly reduced in patients in the radiocephalic fistula group that developed early and late‐term failure (42.9 ± 12 cm/sec vs. 68.4 ± 10 cm/sec, P = 0.01, and 44.1 ± 13 cm/sec vs. 57.7 ± 16 cm/sec, P = 0.038, respectively). Our study, constrained by a smaller, older patient group, was unable to show a statistically significant correlation between FMD, NMD, and fistula success. Any single parameter may not be sufficient to assess vascular health preoperatively. A multifactorial approach incorporating parameters evaluating arterial and venous function might be more effective in predicting fistula success. Further studies on larger patient groups may indeed demonstrate the value of these assessments.     

Alteplase vs. urokinase for occluded hemodialysis catheter: A randomized trial

Introduction Thrombosis of tunneled central venous catheters (CVC) in hemodialysis (HD) patients is common and it can lead to the elimination of vascular sites. To compare the efficacy of alteplase vs. urokinase in reestablishing adequate blood flow through completely occluded vascular catheters. Methods In this randomized study, patients with completely occluded tunneled HD catheters received 40 minutes intracatheter dwell with alteplase (1 mg/mL) or urokinase (5000 IU/mL). Primary endpoint was the proportion of patients with occluded catheters achieving post‐thrombolytic blood flow of ≥250 mL/min. Safety endpoints included the incidence of hemorrhagic and infectious complications. Findings Eligible adult patients (n = 100) were treated with alteplase (n = 44) or urokinase (n = 56). The two groups were similar in gender (male: 51.8% vs. 56.8%, P = 0.35), age (60 ± 12 vs. 59 ± 13 years, P = 0.71), time on dialysis (678 ± 203 vs. 548 ± 189 days, P = 0.77), diabetes and cardiovascular disease (55.6% vs. 70.4%, P = 0.08 and 17.8% vs. 22.7%, P = 0.38, respectively), jugular vein as main vascular access (54.8% vs. 62.5%, P = 0.57), and time of CVC (278 ± 63 vs. 218 ± 59 days, P = 0.67). Primary success with alteplase and urokinase occurred in 42/44 (95%) vs. 46/56 (82%), P = 0.06. Success was not achieved after the second dose of alteplase and urokinase in 1 and 7 cases, respectively (2% vs. 12%, P = 0.075). Serious adverse effects were not observed in both groups. There was no difference between the two groups in infectious complications (P = 0.94). Discussion Alteplase and urokinase are effective thrombolytic agents for restoring HD catheter patency. Our study has revealed a likely slight superiority of alteplase over urokinase for unblocking central lines, but which has enrolled too few patients to be able to detect a difference of this size.     

Long‐term effects of daily hemodialysis on vascular access outcomes: A prospective controlled study

Daily hemodialysis has been associated with surrogate markers of improved survival among hemodialysis patients. A potential disadvantage of daily hemodialysis is that frequent vascular access cannulations may affect long‐term vascular access patency. The study design was a 4‐year, nonrandomized, contemporary control, prospective study of 77 subjects in either 3‐h daily hemodialysis (six 3‐h dialysis treatments weekly; n = 26) or conventional dialysis (three 4‐h dialysis treatments weekly; n = 51). Outcomes of interest were vascular access procedures (fistulagram, thrombectomy and access revision). Total access procedures (fistulagram, thrombectomy and access revision) were 543.2 (95% confidence interval [CI]: 432.9, 673.0) per 1000 person‐years in the conventional dialysis group vs. 400.8 (95% CI: 270.2, 572.4) per 1000 person‐years in the daily hemodialysis dialysis group (incidence rate ratio = 0.74 with 95% CI: from 0.40 to 1.36, P = 0.33), after adjusting for age, gender, diabetes status, serum phosphorus, hemoglobin level and erythropoietin dose, there was no significant differences in incidence rate of total access procedures (P‐value > 0.05). There was no difference in time to first access revision between the daily dialysis and the conventional dialysis groups after adjustment for covariates (hazard ratio = 0.99 95% CI: 0.42, 2.36, P = 0.96). Daily hemodialysis is not associated with increased vascular access complications, or increased vascular access failure rates.