The impact of Arteriovenous fistula anastomosis angle and diameter on steal syndrome: Ultrasound assessment: pilot study

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Abstract: Introduction: Distal hypoperfusion ischemic syndrome (DHIS) or as it is commonly known as steal syndrome. Steal syndrome is a common problem of arteriovenous access patients. It causes hypoxia, distal hypo-perfusion, tissue necrosis, gradual finger loss, and eventual peripheral ischemia when it is reversed from arterial distally to the anastomosis bed. The common cause of this phenomenon includes proximal or distal stenotic lesion, DM, and lack of collaterals. However, there are insufficient studies about the angle of anastomosis or diameter and how they influence steal syndrome. Therefore, we believe there is a correlation between the anastomosis angle and diameter with DHIS in ESRF patients. Method: A pilot retrospective study will involve three groups, 29 patients with Steal syndrome, and the control group will be 61 patients without steal syndrome and 90 patients with ESRD before fistula creation. Patients data will be collected from the vascular laboratory at Hammersmith hospital. Several parameters will be assessed, such as anastomosis angle, VF, and diameter. In addition, the diameter and VF of the artery which used for the creation of the fistula. Clinical history and data demographics will be recorded for analysis. Then analysis and comparing between positive and negative steal anastomotic and volume flow ratio. Results: The results showed that there was no significant association between the angle of anastomosis and developing steal syndrome when the angle is ≥45° with a p-value >0.05 and an angle between 45°-90° showed the lowest percentage of steal syndrome associated in comparisons with other angels. In terms of risk factors, our results showed that Hypercholesteremia and family history of CVD were the major risk factors associated with developing steal syndrome. Moreover, our results suggest that age and gender have an impact on developing steal syndrome as it was associated with >60% with age group above 60 and especially with the female gender. The anastomosis diameter and anastomosis ratio were shown to be extremely significant in steal patients compared to non-steal patients, with a p-value of <0.005. Furthermore, patients with steal syndrome had a significantly higher volume flow and volume flow ratio than the control group, with a p-value of <0.005. Conclusion: This study suggests that patients with anastomosis diameter >3 mm or an anastomosis ratio of ≤1.7mm have a greater chance of developing steal syndrome than those patients with anastomosis diameter of <3 mm or anastomosis ratio of ≥ 1.8mm. In addition, patients with volume flow in the outflow vein exceeding 800 ml/min or volume flow ratio ≥0.95ml/min are more prone to develop steal syndrome than patients with a volume flow rate in the outflow vein < 700 ml/min or volume flow ratio ≤0.7ml/min. Our results showed an angle between 45°-90°, considered preferable as it showed the lowest percentage of steal syndrome associated in comparisons with other angels.