Routine preoperative venous and arterial mapping increases both, construction and maturation rate of upper arm autogenous arteriovenous fistulae

Pre-operative ultrasound mapping before arteriovenous fistula formation: an updated systematic review and meta-analysis

BACKGROUND

Arteriovenous fistula represents the preferred vascular access for patients with kidney failure requiring hemodialysis. Surgeons have traditionally used physical examination to identify the most suitable vessels. This meta-analysis aims to evaluate whether ultrasound mapping should be routinely performed before arteriovenous fistula creation.

METHODS

Medline, Scopus, Web of Science and CENTRAL were systematically searched from inception to November 1, 2022. Randomized controlled trials and cohort studies comparing routine ultrasound mapping to physical examination in terms of arteriovenous fistula patency were included. Meta-analysis was performed by fitting random-effects models. The study protocol has been prospectively registered in PROSPERO (CRD42023402390).

RESULTS

Overall, 18 studies were included, comprising 3655 participants. Routine pre-operative ultrasound mapping was associated with significantly lower rates of primary arteriovenous fistula failure (Risk Ratio-RR: 0.56, 95% confidence intervals-CI: 0.37-0.84, low certainty). A significant outcome was observed by separately pooling randomized controlled trials (RR: 0.37, 95% CI: 0.25-0.54). Routine ultrasound mapping was also associated with significantly higher rates of 1-year primary arteriovenous fistula patency (RR: 1.33, 95% CI: 1.19-1.47, moderate certainty). This effect remained significant in the analysis of randomized controlled trials (RR: 1.26, 95% CI: 1.02-1.56).

CONCLUSIONS

Implementing routine pre-operative ultrasound mapping of vessels is associated with significantly better outcomes in terms of early arteriovenous fistula failure and primary patency rates at 12 months. Further research should confirm the long-term benefits of routine ultrasound examination and evaluate its cost-effectiveness in different populations.

Reliability of preoperative venous mapping ultrasonography in predicting for autogenous arteriovenous fistula maturation

BACKGROUND

Autogenous arteriovenous fistula creation is the preferred route for vascular access for hemodialysis. Although preoperative venous mapping ultrasonography has been advocated as an operative planning adjunct and recently incorporated into the Society for Vascular Surgery clinical guidelines, controversy remains regarding its usefulness for predicting access success. The purpose of the present retrospective clinical study was to test the hypothesis that vein size measured on routine preoperative venous mapping is a poor predictor of primary fistula maturation.

METHODS

Consecutive upper extremity autogenous arteriovenous fistulas created by three dedicated vascular surgeons were retrospectively reviewed. The demographic characteristics, preoperative venous mapping, functional maturation, and patency were analyzed. The clinically relevant variables were tested for predictive significance using a logistic regression model.

RESULTS

A total of 199 upper extremity autogenous arteriovenous fistulas had been created during a 5-year period. Patients were aged 70 ± 16 years (range, 20-96 years), and 62% were men. Most had already been undergoing dialysis before fistula creation (83%), usually via a tunneled central venous catheter (62%). Radial-cephalic, brachial-cephalic, and brachial-basilic arteriovenous fistulas had been created in 82 patients (41%), 76 patients (38%), and 10 patients (5%), respectively. Fistula maturation, defined as a palpable thrill and/or successful cannulation of the fistula with the ability to deliver a flow rate of 400 mL/min, was achieved in 67% of the patients. A higher body mass index was associated with nonmaturation on both univariate and multivariate analyses (success, 28.6 ± 7.7 kg/m²; vs failed, 31.6 ± 9.4 kg/m²; P = .029; odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02-1.10; P < .01). On univariate analysis, the maximum target vein diameter assessed by preoperative venous mapping was slightly larger in the group achieving successful maturation (2.9 ± 1.1 mm vs 2.6 ± 0.9 mm; P = .014). However, neither the maximum target vein diameter nor a target vein size >3 mm was significantly predictive of maturation on multivariate analysis (maximum vein diameter: OR, 0.65; 95% CI, 0.35-1.22; P = .176; vein size >3 mm: OR, 0.91; 95% CI, 0.32-2.60; P = .857). After a median follow-up of 15 months (interquartile range, 26 months), the primary functional patency, primary-assisted patency, and secondary patency rates were 39.1% ± 0.6%, 94.5% ± 0.6%, and 97.9% ± 0.5%. No association of vein diameter with long-term patency was found.

CONCLUSIONS

Despite the national fistula-first initiatives, most patients still undergo access via catheter at the initiation of hemodialysis. The use of routine preoperative venous mapping does not predict successful primary maturation. Also, no clinically useful predictor of fistula maturation was identified in the present study.

Post-operative arterio-venous fistula blood flow influences primary and secondary patency following access surgery

PURPOSE

Primary arteriovenous fistula arterio venous fistula (AVF) formation has proven to be the best and optimal vascular access for the majority of haemodialysis patients. At present there are limited data to suggest which haemodynamic parameters most correlate with the likelihood of early failure. The aim of this study is to identify the haemodynamic predictors of early failure, hence identify which fistulae may benefit from timely pre-emptive intervention.

MATERIAL AND METHODS

Retrospective analysis of data was performed of 201 patients undergoing native AVF creation over a one year period. Demographic details, co-morbidity, preoperative vessel calibre were collected. Flow was measured by duplex ultrasound post operatively.

RESULTS

Preoperative vein calibre (p = 0.01) and fistula flow (p < 0.001) positively affected primary patency. Age, gender, ethnicity, type of fistula, hypertension and preoperative arterial calibre did not influence outcome. Regression analysis showed that the strength of correlation between early postoperative fistula flow and patency decreased progressively with time. Six week flow predicts early, but not late, failure. ROC analysis identified 300 ml/min flow as the best predictor of patency. Fistulae with flow above 300 ml/min were more likely to remain patent over the next 12 months (p < 0.001, HR = 7.4).

CONCLUSION

Postoperative fistula flow of less than 300 ml/min identifies AVFs at high risk of early failure. These may be candidates for early intervention with balloon assisted maturation. The findings of this retrospective cohort study strongly support the need for a more robust prospectively designed trial identifying haemodynamic factors that can predict mid and long-term AVF patency.

Significance of Blunted Venous Waveforms Seen on Upper Extremity Ultrasound

BACKGROUND

Current guidelines recommend vascular mapping ultrasound (US) prior to arteriovenous fistula creation. Blunted venous waveforms (BVWs) suggest central venous stenosis; however, this relationship and one between BVWs and the presence of a central venous catheter (CVC) remain unclear.

METHODS

All patients who received upper extremity vascular mapping US between January 2013 and October 2014 at a single institution were retrospectively reviewed. Patient demographics, comorbidities, US results, pacemaker history, and CVC status were collected. Waveforms were assessed at the proximal subclavian vein/distal axillary vein and interpreted by radiologists. Patients were determined to have central venous stenosis (CVS) if detected by venography within 6 months of US.

RESULTS

There were 342 patients, of which 165 (48%) had a current CVC and 29 (8.5%) had BVW of at least 1 arm. Right-sided BVW were associated with a history of a prior ipsilateral CVC (odds ratio [OR] = 4.5, 95% confidence interval [CI] = 1.6-12.6, P = 0.009). Of the 342 patients, 69 (20%) had a venogram within 6 months. Seventeen (25%) of the 69 patients had CVS, with 7 involving the left subclavian vein, 8 the right subclavian vein, and 3 the superior vena cava (one patient had tandem stenoses). A BVW on the left side was not associated with any CVS. A BVW on the right side was associated with an ipsilateral CVS (OR = 5.8, 95% CI = 1.2-27.4, P = 0.04). This association persisted in the setting of a prior CVC (relative risk = 1.3, 95% CI = 0.9-2, P = 0.01).

CONCLUSIONS

There are associations between right-sided BVW and an ipsilateral subclavian vein stenosis. We recommend that hemodialysis access planning includes venography to rule out central vein stenosis in patients with BVW, especially if right-sided and in the setting of a prior CVC.

Racial and Gender Differences in Arterial Anatomy of the Arm

Prior studies have shown racial and gender differences with respect to maturation of arteriovenous fistulas. Women and minorities have lower maturation rates for unclear reasons. Small arterial diameter and high brachial artery bifurcation (HBB) are also implicated in reduced maturation rates. We sought to correlate differences in upper extremity arterial anatomy to race and gender. All upper extremity vascular mapping ultrasounds from 2013 to 2014 were retrospectively reviewed. A total of 509 arms in 284 patients were evaluated. Men had significantly higher mean arterial diameters than women at the elbow brachial (4.7 vs 3.9 mm, P < 0.01) and wrist radial arteries (2.1 vs 1.9 mm, P = 0.03). There were 20 (7%) patients with HBB of at least one arm, and 7 (2.5%) patients with bilateral HBB. African-American patients had significantly higher rates of both unilateral HBB (15.9% vs 5.4%, P = 0.02) and bilateral HBBs (9.1% vs 1.3%, P = 0.01). In conclusion, men had significantly larger arteries than women, and African-Americans had a higher rate of HBB than non-African-Americans. Consideration should be given for routine preoperative ultrasound to assess arterial anatomy before arteriovenous fistulas creation, particularly in women and in African-Americans.

Establishment of a rat autogenous arteriovenous fistula model following 5/6 nephrectomy

The aim of this study was to establish a stable rat model of autogenous arteriovenous fistula (AVF) with chronic renal function insufficiency. Forty Sprague-Dawley rats were randomly divided into an experimental group (n=20) and sham surgery group (n=20) and a 5/6 nephrectomy model was established in the rats. One week later, in the experimental group, the ipsilateral caroid artery was inserted into the external jugular vein by a cuff technique to establish a carotid arteriovenous fistula; in the sham group, the external jugular vein and carotid artery were dissociated. At 7 and 28 days following the establishment of the AVF, the renal functions of the two groups were measured. Hematoxylin and eosin staining and double collagen and elastin staining were conducted to evaluate the area of intimal hyperplasia in the external jugular vein, and the expression of α-smooth muscle actin in the vein was investigated by immunohistochemistry. The creatinine and urea nitrogen levels in the experimental group at each time-point were significantly higher than those in the sham surgery group (P<0.05). The intimal hyperplasia of the external jugular vein of the experimental group was increased significantly compared with that in the sham group at each time-point (P<0.05). The model, which is easy to establish and simple to master, provides a new and feasible experimental method for the study of intimal hyperplasia associated with autogenous AVF in chronic renal insufficiency, and is worthy of wider use.

Vascular access today

The number of patients with chronic kidney disease requiring renal replacement therapy has increased worldwide. The most common replacement therapy is hemodialysis (HD). Vascular access (VA) has a key role for successful treatment. Despite the advances that have taken place in the field of the HD procedure, few things have changed with regards to VA in recent years. Arteriovenous fistula (AVF), polytetrafluoroethylene graft and the cuffed double lumen silicone catheter are the most common used for VA. In the long term, a number of complications may present and more than one VA is needed during the HD life. The most common complications for all of VA types are thrombosis, bleeding and infection, the most common cause of morbidity in these patients. It has been estimated that VA dysfunction is responsible for 20% of all hospitalizations. The annual cost of placing and looking after dialysis VA in the United States exceeds 1 billion dollars per year. A good functional access is also vital in order to deliver adequate HD therapy. It seems that the native AVF that Brescia and Cimino described in 1966 still remains the first choice for VA. The native forearm AVFs have the longest survival and require the fewest interventions. For this reason, the forearm AVF is the first choice, followed by the upper-arm AVF, the arteriovenous graft and the cuffed central venous catheter is the final choice. In conclusion, VA remains the most important issue for patients on HD and despite the technical improvements, a number of problems and complications have to be resolved.

Prevalence of arteriovenous fistulas in incident hemodialysis patients: correlation with patient factors that may be associated with maturation failure

BACKGROUND

Lok et al previously reported a risk equation for arteriovenous fistula (AVF) maturation failure. It is unclear whether this model or a more comprehensive model correlates with incident AVF use in the US hemodialysis population.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

195,756 adult patients initiating outpatient hemodialysis therapy in the United States between July 1, 2005, and December 31, 2009, with 6 months or more prior nephrology care.

PREDICTOR

Patient characteristics (age, peripheral vascular disease, coronary artery disease, and race) populating the AVF maturation failure risk equation and other demographic and clinical variables from the Centers for Medicare & Medicaid Services (CMS) Medical Evidence Report (CMS 2728).

OUTCOMES & MEASUREMENTS

AVF use at first outpatient dialysis treatment as recorded on the CMS 2728.

RESULTS

Using the risk categories defined by Lok et al, AVF use varied from 19.0% (very high risk) to 25.6% (low risk). In a model using only these risk categories, logistic regression showed lower ORs for moderate-, 0.90 (95% CI, 0.88-0.93); high-, 0.80 (95% CI, 0.78-0.83); and very high-risk patients, 0.68 (95% CI, 0.63-0.73) compared with low risk. In the expanded model, odds were lower for women, blacks, Hispanics, age older than 85 years, diabetes, peripheral vascular disease, congestive heart failure, other cardiac disease, and underweight. Odds were higher for hypertension, overweight, obesity, 12 months or more nephrologist care, most insurance types, and each successive year after 2005. Despite associations, the C statistic for the expanded model was 0.64.

LIMITATIONS

This analysis is limited by lack of access creation history before dialysis therapy initiation and minimal external validation of CMS 2728 data.

CONCLUSIONS

Clinical risk factors identified by Lok and expanded in this analysis have limited ability to predict incident AVF use. Even patients judged at highest risk can have successful AVF construction and initiate dialysis therapy through a functioning AVF.