#2515 Optimizing brachial-basilic arteriovenous fistula outcomes: insights from a mapping and pre-transposition review
Authors: Cunha Ana Cristina Santos , Sousa Sofia , Braga Beatriz Gil , Dias Bruno Fraga , Pereira Sandra , de Bessa e Silva João Pedro Peixoto , Sousa Da Silva Silva Maria Fernanda , Queirós José , Almeida Paulo 
Published: May 2024

Abstract

Background and Aims
Brachial- Basilic arteriovenous fistulas (BBAVF) are an option for our patients when superficial vascular patrimony is lacking, but they pose technical and time challenges due to the necessity of a second-stage surgical transposition. The literature reports a 47% primary patency rate within the first year. BBAVFs are associated with higher incidences of steal syndrome and increased stenosis rates, commonly requiring interventions. This study aims to provide insights about optimizing BBAVF outcomes through a comprehensive mapping and pre-transposition evaluation.

Method
We developed a retrospective single-centre study from 2016 to 2022 that included 101 patients with BBAVFs mapped and constructed at Centro Hospitalar Universitário de Santo António. Mapping and pre-transposition evaluations data were collected from our digital records and the dialysis centre's provided insights about the BBAVFs outcomes through telephonic contact. A comparative analysis between patients achieving one-year primary patency (1Y-P) and those who did not (No 1Y-P) was performed, considering mapping variables (brachial artery and basilic vein diameters) and pre-transposition variables (brachial artery flow and basilic vein diameter).

Results
At 12 months our primary patency rate was 72.27%. The 1Y-P and No 1Y-P groups showed no significant differences concerning to baseline characteristics such as sex (p = 0.536), age (p = 0.489), and major comorbidities like diabetes (p = 0.929), ischemic heart disease (p = 0.741), peripheral arterial disease (p = 0.174), kidney transplantation (p = 0.384), and previous haemodialysis (p = 0.384).
When the BBAVFs were constructed as the first access, they were significantly associated with less primary patency at 12 months (1Y-P n = 32 (43.84%) vs No 1Y-P n = 23 (82.14%); p &lt; 0.001).
In the vascular mapping the brachial artery (1Y-P 4.32 ± 0.86 mm vs No 1Y-P 4.11 ± 0.78 mm; p = 0.454) and basilic vein (1Y-P 3.90 ± 1.11 mm vs No 1Y-P 3.59 ± 0.88 mm; p = 0.249) diameters were larger in the 1Y-P group, although without statistically significance. It is important to emphasise that only 12 BBAVFs were constructed with less than 3 mm basilic veins and we only had 50% 12-month primary patency in those patients.
Pre-transposition flow was significantly higher in patients with primary patency at 12 months (1Y-P 1069,77 ± 311,89 ml/min vs No 1Y-P 985,00 ± 500,83 ml/min; p = 0.018) and basilic vein diameter was higher in the same group, but without statistical significance (1Y-P 6.50 ± 1.19 mm vs No 1Y-P 6.14 ± 1.53 mm; p = 0.123).

Conclusion
Our primary patency rate was higher than the described in the literature, which could be a reflection of the organized mapping process in our centre that excludes limit size veins from the BBAVF construction.
Patients with BBAVF as their initial access face worse outcomes with decreased primary patency time, probably due to lack of intrinsic vascular patrimony. Stringent construction criteria are warranted in those cases.
Contrary to expectations, vessel diameters did not show significant relevance, prompting consideration of factors like distensibility or vessels calcifications as potentially influential. However, we have to underline that the average mapping basilic vein diameter was greater than 3 mm in both groups, which suggests a pre-selection is already carried out in our centre, and, even though there was not statistical significance, the 1Y-P group had bigger basilic veins in the vascular mapping. Our results were worst in the 12 BBAVFs constructed with less than 3 mm basilic veins.
BBAVFs pre-transposition evaluation importance is emphasized by the association of higher pre-transposition brachial artery flow rates with improved outcomes.
This research highlights the importance of mapping and pre transposition evaluation for optimal BBAVF outcomes, but further studies need to be done with longer follow up times and including more vascular access mapping criteria.