Delayed post-surgical development of dural arteriovenous fistula after cervical meningocele repair

A 34-year-old female patient presented with an intracranial subarachnoid hemorrhage and was found to have a dural arteriovenous fistula at the site of previous cervical meningocele repair. Subsequent occlusion was achieved with endovascular embolization. To our knowledge, the phenomenon of the development of a spinal dural fistula at the site of a meningocele repair has not been recorded before.

Preserving arteriovenous fistula outcomes during surgical training

PURPOSE: Arteriovenous fistulae (AVFs) are the preferred option for vascular access, as they are associated with lower mortality in hemodialysis patients than in those patients with arteriovenous grafts (AVGs) or central venous catheters (CVCs). We sought to assess whether vascular access outcomes for surgical trainees are comparable to fully trained surgeons.

METHODS: A prospectively collected database of patients was created and information recorded regarding patient demographics, past medical history, preoperative investigations, grade of operating surgeon, type of AVF formed, primary AVF function, cumulative AVF survival and functional patency.

RESULTS: One hundred and sixty-two patients were identified as having had vascular access procedures during the 6 month study period and 143 were included in the final analysis. Secondary AVF patency was established in 123 (86%) of these AVFs and 89 (62.2%) were used for dialysis. There was no significant difference in survival of AVFs according to training status of surgeon (log rank x2 0.506 p=0.477) or type of AVF (log rank x2 0.341 p=0.559). Patency rates of successful AVFs at 1 and 2 years were 60.9% and 47.9%, respectively.

CONCLUSION: We have demonstrated in this prospective study that there are no significant differences in outcomes of primary AVFs formed by fully trained surgeons versus surgical trainees. Creation of a primary AVF represents an excellent training platform for intermediate stage surgeons across general and vascular surgical specialties.

Patient survival following arteriovenous fistula formation

PURPOSE: Efforts to promote arteriovenous fistulas (AVFs) have been successful in increasing the prevalence of AVF use as the primary vascular access for haemodialysis (HD). Sustained preference for AVF use may not be the most appropriate vascular access choice for all patient groups. Arteriovenous grafts (AVGs) offer advantages of earlier use and lower primary failure rates compared to AVFs so may be preferable for patients where short-term vascular access is needed. This study was designed to assess comparative mortality in different age groups following AVF formation.

METHODS: A prospective cohort of patients having AVF creation was recruited. Patients were subdivided into three age groups: Group A: lt;50 years; Group B: 50-74 years and Group C: ≥75 years. Survival curves and Cox regression analysis were performed on each of these groups.

RESULTS: One hundred and thirty-four patients (n = 134) were recruited into the study. The prevalence of diabetes increased significantly with age. As expected, mortality was higher in older age groups (log rank (Mantel-Cox) 19.227; p = 0.0001). Mortality rates at 1 year were 0% in group A, 12.5% in group B and 29.1% in group C. Medium-term mortality at 4 years was 7.9% in group A, 39.1% in group B and 54.8% in group C.

CONCLUSIONS: We found a significantly higher mortality rate in patients ≥75 years in comparison to those lt;75 years. The choice of vascular access modality should be tailored to the individual with particular reference to the patient's expected survival.

Current tools for prediction of arteriovenous fistula outcomes

It remains challenging to accurately predict whether an individual arteriovenous fistula (AVF) will mature and be useable for haemodialysis vascular access. Current best practice involves the use of routine clinical assessment and ultrasonography complemented by selective venography and magnetic resonance imaging. The purpose of this literature review is to describe current practices in relation to pre-operative assessment prior to AVF formation and highlight potential areas for future research to improve the clinical prediction of AVF outcomes.

Arteriovenous fistula outcomes in the elderly

OBJECTIVE: Over several decades, there has been an increase in the number of elderly patients requiring hemodialysis. These older patients typically have an increased incidence of comorbidities including diabetes, hypertension, and peripheral vascular disease. We undertook a systematic review of the current literature to assess outcomes of arteriovenous fistula (AVF) formation in the elderly and to compare the results of radiocephalic AVFs vs brachiocephalic AVFs in older patients.

METHODS: A literature search was performed using MEDLINE, Embase, PubMed, and the Cochrane Library. All retrieved articles published before December 31, 2014 (and in English) primarily describing the creation of hemodialysis vascular access for elderly patients were considered for inclusion. We report pooled AVF patency rates and a comparison of radiocephalic vs brachiocephalic AVF patency rates using odds ratios (ORs).

RESULTS: Of 199 relevant articles reviewed, 15 were deemed eligible for the review. The pooled 12-month primary and secondary AVF patency rates were 53.6% (95% confidence interval [CI], 47.3-59.9) and 71.6% (95% CI, 59.2-82.7), respectively. Comparison of radiocephalic vs brachiocephalic AVF patency rates demonstrated that radiocephalic AVFs have inferior primary (OR, 0.72; 95% CI, 0.55-0.93; P = .01) and secondary (OR, 0.76; 95% CI, 0.58-1.00; P = .05) patency rates.

CONCLUSIONS: This meta-analysis confirms that adequate 12-month primary and secondary AVF patency rates can be achieved in elderly patients. Brachiocephalic AVFs have both superior primary and secondary patency rates at 12 months compared with radiocephalic AVFs. These important data can inform clinicians' and patients' decision-making about suitability of attempting AVF formation in older persons.

Investigating clinical predictors of arteriovenous fistula functional patency in a European cohort

Background: Arteriovenous fistula (AVF) failure to mature (FTM) rates contribute to excessive dependence on central venous catheters for haemodialysis. Choosing the most appropriate vascular access site for an individual patient is guided largely by their age, co-morbidities and clinical examination. We investigated the clinical predictors of AVF FTM in a European cohort of patients and applied an existing clinical risk prediction model for AVF FTM to this population.
Methods: A prospective cohort study was designed that included all patients undergoing AVF creation between January 2009 and December 2014 in a single centre (Belfast City Hospital) who had a functional AVF outcome observed by March 2015.
Results: A total of 525 patients had a functional AVF outcome recorded and were included in the FTM analysis. In this cohort, 309 (59%) patients achieved functional AVF patency and 216 (41%) patients had FTM. Female gender [P < 0.001, odds ratio (OR) 2.03 (CI 1.37–3.02)] and lower-arm AVF [P < 0.001, OR 4.07 (CI 2.77–5.92)] were associated with AVF FTM. The Lok model did not predict FTM outcomes based on the associated risk stratification in our population.
Conclusions: In this European study, female gender was associated with twice the risk of AVF FTM and a lower-arm AVF with four times the risk of FTM. The FTM risk prediction model was not found to be discriminative in this population. Clinical risk factors for AVF FTM vary between populations;we would recommend that units investigate their own clinical predictors of FTM to maximize AVF functional patency and ultimately survival in dialysis patients. Clinical predictors of AVF FTM may not be sufficient on their own to improve vascular access functional patency rates.

Preoperative radial artery volume flow is predictive of arteriovenous fistula outcomes

Objective: Guidelines recommend the creation of a wrist radiocephalic arteriovenous fistula (RAVF) as initial hemodialysis vascular access. This study explored the potential of preoperative ultrasound vessel measurements to predict AVF failure to mature (FTM) in a cohort of patients with end-stage renal disease in Northern Ireland

.Methods: A retrospective analysis was performed of all patients who had preoperative ultrasound mapping of upper limb blood vessels carried out from August 2011 to December 2014 and whose AVF reached a functional outcome by March 2015.

Results: There were 152 patients (97% white) who had ultrasound mapping andan AVF functional outcome recorded; 80 (54%) had an upper arm AVF created, and 69 (46%) had a RAVF formed. Logistic regression revealed that female gender (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.12-5.55; P = .025), minimum venous diameter (OR, 0.6; 95% CI, 0.39-0.95; P = .029), and RAVF (OR, 0.4; 95% CI, 0.18-0.89; P = .026) were associated with FTM. On subgroup analysis of the RAVF group, RAVFs with an arterial volume flow <50 mL/min were seven times as likely to fail as RAVFs with higher volume flows (OR, 7.0; 95% CI, 2.35-20.87; P < .001).

Conclusions: In this cohort, a radial artery flow rate <50 mL/min was associated with a sevenfold increased risk of FTM in RAVF, which to our knowledge has not been previously reported in the literature. Preoperative ultrasound mapping adds objective assessment in the clinical prediction of AVF FTM.

Arterial stiffness and arteriovenous fistula failure of maturation

PURPOSE: Increased arterial stiffness is a common finding in patients with end-stage renal disease. Following creation of an arteriovenous fistula (AVF), appropriate dilation of the feeding artery must occur to facilitate AVF maturation. Arterial stiffness may impair the arterial dilation required to facilitate AVF development and contribute to subsequent failure to mature (FTM). The aim of this pilot study was to investigate the association between measurements of central and peripheral arterial stiffness, and AVF FTM.

METHODS: Patients undergoing AVF creation in a single centre (Belfast City Hospital, UK) between January and December 2015 were invited to have their carotid-femoral pulse wave velocity (PWV), brachial-radial PWV and augmentation index (AI) measured prior to AVF creation. Subsequent AVF outcomes were identified.

RESULTS: Fifty-nine patients who had an AVF procedure were included in the final analysis (mean age 62 years); 50.8% had diabetes mellitus. The mean pre-operative arterial diameter for all AVFs was 3.9 mm. Average values for carotid-femoral PWV were 9.5 m/s, brachial-radial PWV 7.7 m/s and AI 25.6%. Using logistic regression, these arterial stiffness parameters did not predict AVF FTM: carotid-femoral PWV (P = 0.20), brachial-radial PWV (P = 0.13), AI (P = 0.50).

CONCLUSIONS: This is the largest study to date exploring the association between arterial stiffness and AVF FTM. The measured central and peripheral arterial stiffness parameters were not associated with AVF FTM. Further research is needed to define if non-invasive arterial physiological measurements would be clinically useful in the prediction of AVF FTM.

Treatment of intestinal Behçet's syndrome with chimeric tumour necrosis factor alpha antibody

Few patients with Behçet's syndrome have gastrointestinal ulceration. Such patients are difficult to treat and have a higher mortality. Faced with refractory symptoms in two patients with intestinal Behçet's, we used the tumour necrosis factor alpha (TNF-alpha) monoclonal antibody infliximab to induce remission. Both women (one aged 27 years, the other 30 years) presented with orogenital ulceration, pustular rash, abdominal pain, bloody diarrhoea due to colonic ulceration, weight loss, and synovitis. One had thrombophlebitis, digital vasculitis, perianal fistula, and paracolic abscess; the other had conjunctivitis and an ulcer in the natal cleft. Treatment with prednisolone, methyl prednisolone, and thalidomide in one and prednisolone, colchicine, and cyclosporin in the other was ineffective. After full discussion, infliximab (3 mg/kg, dose reduced because of recent sepsis in one, and 5 mg/kg in the other) was administered. Within 10 days the ulcers healed, with resolution of bloody diarrhoea and all extraintestinal manifestations. A second infusion of infliximab was necessary eight weeks later in one case, followed by sustained (>15 months) remission on low dose thalidomide. Remission was initially sustained for 12 months in the other but thalidomide had to be stopped due to intolerance, and a good response to retreatment lasted only 12 weeks without immunosuppression, before a third infusion. The cause of Behçet's syndrome is unknown but peripheral blood CD45 gammadelta T cells in Behçet's produce >50-fold more TNF-alpha than controls when stimulated with phorbol myristate acetate and anti-CD3. Infliximab could have a role for inducing remission in Behçet's syndrome.

Infectious keratitis in a paracentesis tract

A paracentesis is performed in glaucoma procedures as a flat, beveled tract to allow access into the anterior chamber after the filtration fistula is made. Complications related to the paracentesis are infrequent because it is a self-sealing wound. The authors report a case of infectious keratitis that developed in a paracentesis tract.

Dysfunctional filtering blebs

Guarded filtration surgery is commonly used to control the intraocular pressure (IOP) in glaucomatous patients. Filtration surgery lowers the IOP by creating a fistula between the inner compartments of the eye and the subconjunctival space (i.e., filtering bleb). There are several options to improve the function of filtering blebs and to prevent their failure. However, improvement of IOP control after guarded filtration procedures is associated with a higher frequency of bleb-related complications. Early (e.g., bleb leak, excessive filtration, flat anterior chamber, filtration failure) and late (e.g., bleb leak, excessive filtration and hypotony, symptomatic blebs, bleb encapsulation, filtration failure, bleb infection) complications associated with filtering procedures should be managed adequately to prevent further problems. Techniques to improve the function of filtering blebs and to treat postoperative complications have progressed over the past decade.

The influence of comorbidity on the risk of access-related bacteremia in chronic hemodialysis patients.

Access-related bacteremia is an important cause of morbidity in chronic hemodialysis patients. The incidence of bacteremia is higher in patients dialyzing through a tunneled central venous catheter (TCVC) compared with an arteriovenous fistula (AVF). Our aim was to explore if this is explained by patient comorbidity. Two groups of chronic hemodialysis outpatients were compared: all patients who dialyzed through a TCVC at any time during 2003 and were fit enough to subsequently have a functioning AVF or renal transplant even if it was after 2003 (Group 1; n=93); and all patients who dialyzed through a TCVC in 2003 and were not fit enough to have a functioning AVF or renal transplant (Group 2; n=119). Episodes of bacteremia (n=71) were identified and those not related to access were excluded. Patients in Group 1 were younger than Group 2 (57.5 years vs. 64.8 years; P=0.001). The incidences of bacteremia in Groups 1 and 2 were, respectively, 0.31 and 0.44 episodes per 1000 patient days while dialyzing through an AVF (P=0.77), and 2.21 and 2.27 per 1000 days while dialyzing through a TCVC (P=0.91). The 3-year actual survival from January 1, 2003 to January 1, 2006 was significantly higher in Group 1 than in Group 2 (80.6% vs. 26.1%; P<0.0001) confirming the higher comorbidity of the patients in Group 2. Patients dialyzing through a TCVC (compared with an AVF) have a significantly higher risk of access-related bacteremia, irrespective of comorbidity.