Cephalic arch stenosis in patients with fistula access for hemodialysis: relationship to diabetes and thrombosis

Numerous studies have identified the fistula as the best access for hemodialysis with fewest complications. The radiocephalic fistula (RCF) is the first access of choice, but often results in poor maturation. Therefore, an increased number of brachiocephalic fistulas (BCF) have been placed. Cephalic arch stenosis (CAS) can occur in patients with fistula access. The current study was done to determine the incidence and associated comorbidities in patients with BCF or RCF who have CAS. A retrospective review of 450 hemodialysis patients in 3 outpatient hemodialysis units between July 1, 2000 and July 1, 2005 (60 months) was preformed. We reviewed demographics, medications, and indications for venograms. Interventional Radiologists reviewed the venograms for evidence of CAS. Radiology reports were screened to determine incidence of thrombosis, treatment with either angioplasty or stent placement and if a complication such as venous rupture occurred. One hundred and twenty-seven patients had fistula access with at least 1 venogram. Of these, 30 were RCF and 97 were BCF. Cephalic arch stenosis occurred in 77% of patients with BCF and in 20% of patients with RCF. Those with diabetes had a lower rate of occurrence than those without (p<0.01). Cephalic arch stenosis led to a high rate of thrombosis (p<0.01). The probability of having multiple radiology procedures was higher with CAS than without (p<0.01). Cephalic arch stenosis is an important problem in hemodialysis patients who have fistula access, and contributes to thrombosis. Diabetes was found to have a negative association with CAS for undefined reasons. Attempts to understand this relationship are important.     

Hemodialysis access at initiation in the United States, 2005 to 2007: Still "Catheter First"

Despite the broad consensus that native arteriovenous fistula is the access of choice for hemodialysis, national-level information about vascular access at dialysis initiation has been unavailable in the United States. For incident hemodialysis patients, June 2005 to October 2007 (n=220,157), vascular access type was determined from the new Centers for Medicare & Medicaid Services Medical Evidence Report (form CMS-2728). Proportions with each type at first dialysis, demographic and clinical associations of each type, and associations between initial access type and survival were assessed. The mean patient age was 63.6 years; 29.4% of patients were African American, and for 44.5%, end-stage renal disease was due to diabetes. Vascular access proportions were: fistula, 13.2% of patients; graft, 4.3%; catheter/maturing fistula, 16.0%; catheter/maturing graft, 3.3%; and catheter alone, 63.2%. Adjusted odds ratios (vs. fistula) of catheter use alone were ≥1.50 for lack of insurance (1.62 [95% confidence interval 1.62–1.68]), nephrologist care for 0 to 12 months (2.75 [2.69–2.81]), other (2.19 [2.09–2.29]), or unknown (1.53 [1.44–1.63]) cause of renal disease, institutional residence (1.51 [1.45–1.57]), and 7 of 18 end-stage renal disease networks. Over a mean follow-up of 1 year, 26.0% of the study population died. Compared with fistula, adjusted mortality hazards ratios were 1.39 (1.32–1.47) for grafts, 1.49 (1.44–1.55) for catheters/maturing fistulas, 1.74 (1.65–1.84) for catheters/maturing grafts, and 2.18 (2.11–2.26) for catheters alone. While geographic variability is pronounced, vascular access at dialysis inception is typically suboptimal; suboptimal access exhibits a graded association with mortality. Lack of timely access to specialty care appears to limit optimal access.     

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.     

Vascular access for hemodialysis: experience of a team of nephrologists

A survey conducted by Bonucchi et al. underlined the different types of doctors placing arteriovenous fistula (AVF) for hemodialysis in the United States and Europe (in particular Italy). In fact, nephrologists definitely prevail in Italy, where almost 48.8% of nephrologists place an AVF themselves or with the help of a vascular surgeon (26.4%). In Europe, only 35% do so, whereas 89% of AVF are performed by surgeons in the United States. In 98% of the cases occurring at our center, the AVF was placed and reviewed by the nephrologists. This paper reports surgery cases related to the period between January 1983 and September 2006. Over this time, 1386 operations for placing and reviewing vascular access were conducted. Among these, 47 (3.3%) were related to a cuffed central venous catheter (CVC); 1138 (80.2%) related to a distal AVF; 201 (10.6%) related to a proximal AVF; and 51 (3.6%) related to an arteriovenous graft (AVG). In addition, 33 (2.3%) operations performed before January 1983 relating to AV Scribner shunts were included. Arteriovenous fistulas or AVGs were provided to our patients (only 2.6% of them have a CVC), and AVF rescue operations were performed in the shortest possible time with advantages for the patient and his vascular access.     

Stenosis in hemodialysis arteriovenous fistula: evaluation and treatment

Vascular access complications are one of the main causes associated with an increase in morbidity and mortality in stage 5 chronic kidney disease patients. The arteriovenous fistula is regarded as the vascular access of choice for hemodialysis (HD) because of its superior patency and lower complication rates. Stenosis is considered the major cause of dysfunction of arteriovenous fistula. Despite the relatively low thrombosis rates of arteriovenous fistula, surveillance programs are necessary for detection of stenosis. We report a case of a HD patient who had never achieved an adequate Kt/V since the start of maintenance HD. During the investigation, abnormal findings were found on physical examination of the fistula, in addition to an alteration in intra-access pressure (IAP) measurements. A venous stenosis was diagnosed by Doppler ultrasound and then promptly treated with percutaneous transluminal angioplasty. The purpose of the discussion is to highlight the peculiarities of arteriovenous fistulae, methods of surveillance, including physical examination, IAP, recirculation, and measurements of blood flow, and the importance of the correction procedures for the stenosis.     

A pilot study of genetic polymorphisms and hemodialysis vascular access thrombosis

Vascular access thrombosis (VAT) remains a significant problem worldwide. This study determined the association between VAT and 7 candidate gene polymorphisms (factor V Leiden 1691G>A, factor II 20210G>A, methylenetetrahydrofolate reductase 677C>T, angiotensin converting enzyme 287 base pair (bp) insertion/deletion, transforming growth factor-β1 869T>C and 915G>C, NOS3 −786T>C and intron 4 27 bp tandem repeat, and endotoxin receptor CD14 −159C>T). This was a retrospective case-control pilot study conducted in 101 hemodialysis patients at a large tertiary-care, University health-science center. Sixty cases that experienced frequent VAT and 41 controls that had not experienced VAT in at least 3 years were evaluated for demographics and genotyping. These data were summarized, and univariable and multivariable regression models were constructed. Univariate VAT predictors included the NOS3 420 bp allele (P=0.03) and the presence of a central venous dialysis catheter (P<0.01). Aspirin use was protective against VAT (P=0.02). In the multivariate analysis, the dialysis access type remained a significant predictor of thrombosis (P<0.01), while aspirin use retained its protective status (P=0.01). Statin use was associated with the cases (P=0.02); however, the NOS3 420 bp allele failed to improve the model. These data confirm that central venous dialysis catheter access is associated with thrombosis, while aspirin use appears protective. The NOS3 420 bp allele may have an association with thrombosis; however, further epidemiologic data evaluating large dialysis registries are needed to confirm our observation.     

Use of a "composite" vascular access graft in a young child on hemodialysis

Although arterio-venous fistulae (AVF) are currently considered to be the first choice of permanent vascular access for hemodialysis, there are some patients who are not candidates for fistulae and synthetic grafts provide other options. The Thoratec (Vectra) polyurethane vascular access graft is a new prosthetic graft that may be cannulated within days of insertion due to "self-sealing" properties. However, a tendency for kinking at the suture site due to the strong elasticity of this graft, leading to undesirable complications such as thrombosis, have been reported. We describe a surgical modification of the anastomosis by interposing a segment of expanded polytetrafluoroethylene graft (ePTFE, Venaflo) between the native vessels and the polyurethane graft sections in a pediatric patient. This modification may overcome the kinking complication associated with use of the polyurethane graft and the resulting thrombosis.     

Carotid-jugular arteriovenous fistula: a case report of an iatrogenic complication following internal jugular vein catheterization for hemodialysis access

We report a case of diabetic end-stage renal disease patient who presented with a right common carotid artery jugular arteriovenous fistula as a complication of the insertion of a polyurethane double-lumen hemodialysis catheter into the right internal jugular vein .On physical examination of the neck, a pulsating mass with a palpable thrill and a bruit was noted in the right subclavicular region. The diagnosis was confirmed by color doppler ultrasonography of the neck and carotid angiography. The review of the literature suggests the occurrence of this complication as rather rare. The fistula was successfully repaired surgically. It is emphasized that while securing the access, a thorough physical examination with a special emphasis on seeking any neck swellings, thrill, and bruit along with routine use of vascular doppler for securing dialysis access is recommended.     

Current concepts: tissue engineering and regenerative medicine applications in the ankle joint

Tissue engineering and regenerative medicine (TERM) has caused a revolution in present and future trends of medicine and surgery. In different tissues, advanced TERM approaches bring new therapeutic possibilities in general population as well as in young patients and high-level athletes, improving restoration of biological functions and rehabilitation. The mainstream components required to obtain a functional regeneration of tissues may include biodegradable scaffolds, drugs or growth factors and different cell types (either autologous or heterologous) that can be cultured in bioreactor systems (in vitro) prior to implantation into the patient. Particularly in the ankle, which is subject to many different injuries (e.g. acute, chronic, traumatic and degenerative), there is still no definitive and feasible answer to ‘conventional’ methods. This review aims to provide current concepts of TERM applications to ankle injuries under preclinical and/or clinical research applied to skin, tendon, bone and cartilage problems. A particular attention has been given to biomaterial design and scaffold processing with potential use in osteochondral ankle lesions.     

Blood loss during vascular access cannulation: quantification using the weighed gauze and drape method

Anemia is an important complication of chronic renal disease, with a significant impact on the morbidity, quality of life, and mortality in this group of patients. Inadequate erythropoietin production, reduced life span of erythrocytes in uremic serum, bone marrow suppression by uremic toxins, chronic inflammation, and contaminants in the water treatment unit are recognized etiological causes of anemia in chronic kidney disease patients. Little attention has been paid to possible contributions of small but continual loss of blood during vascular access cannulation for hemodialysis in these patients. The aim of this study is to quantify the volume of blood loss during femoral vein cannulation in patients on hemodialysis. The average volume of blood loss during femoral cannulation was evaluated using a simple and inexpensive procedure of deriving volume of blood lost, from the weights of soaked gauze and drape during the access cannulation procedure. The mean blood loss per procedure during femoral cannulation was 36.52 mL+/-2.70 SD, with a range of 6.47 to 100.20 mL. The calculated average weekly loss in patients on thrice-weekly dialysis schedule is 109.56 mL of blood, with a monthly loss of 438.24 mL. Cumulative blood loss during femoral vein cannulation appears to be significant. Its contribution in the sustenance of anemia in hemodialysis patients deserves further evaluation.     

HCO3 increment in arterial line can reveal significant vascular access recirculation in high-flux hemodialysis: a preliminary report

We report a new and simple way that can reveal the presence of vascular access recirculation (VAR) in patients undergoing hemodialysis (HD). Acid-base and blood gas parameters (pH, pO(2), pCO(2), and HCO(3)) were measured in blood samples drawn from an arterial fistula needle before the initiation of HD and from arterial and venous lines simultaneously 5 min later, in 31 patients (group A). Vascular access recirculation was measured using the glucose infusion test (GIT) immediately after the withdrawal of the 5-min samples. The same study was repeated in 30 patients in whom HD lines were reversed (group B). A comparison with baseline (predialysis) values of an analysis of the arterial line in group A at 5 min revealed that pCO(2) increased by 1.14+/-2.5 mmHg and HCO(3) by 0.6+/-0.6 mM/L (p<0.02 and p<0.00001, respectively). The corresponding pO(2) and pH values did not show significant differences. Glucose infusion test at 5 min (GITa) was -0.058+/-0.03%. A comparison with baseline (predialysis) values of an analysis of the arterial line in group B at 5 min revealed that pCO(2) increased by 7.7+/-3.5 mmHg and HCO(3) by 2.9+/-1.0 mM/L (p<0.000001 in each case). The pH level was significantly lower in comparison with baseline values (p<0.00001), while pO(2) did not show a significant difference. Glucose infusion test at 5 min (GITb) was 12.0+/-6.1% (p<0.000001 in comparison with GITa values). Clinically significant VAR was defined as HCO(3) increment >1.8 mM/L, based on the receiver-operating characteristics curve, which showed a threshold value of HCO(3) increment >1.8 mmol/L as a predictor of GIT recirculation. Five minutes after the initiation of high-flux HD with a 0 ultrafiltration rate, there is a small increment in arterial HCO(3) values relative to predialysis values. Clinically significant VAR is present when this increment is higher than 1.8 mM/L.