Advanced Ultrasound Applications for Predicting AVF Outcomes

Plain-language summary

Haemodialysis is a renal replacement therapy that can be introduced to patients with end-stage renal disease (ESRD) to help them maintain a good healthy life. The patient's blood is pumped through a dialysis machine to remove excess fluid, salt and waste, then it is pumped back into the patient's circulation system. In order to carry out haemodialysis, vascular access (VA) is required to connect the patient to the dialysis machine. Patients have only three options of vascular access: arteriovenous fistula (AVF), an anastomosis between a native vein and an artery; arteriovenous graft (AVG), a connection between a synthetic tube and native blood vessels; and (3) central line, a cuffed catheter placed in a large neck vein. Arteriovenous fistulas are the preferred method for VA because of their longevity and causing the least number of complications. Although there are a number of factors that may increase the probability of AVF failure rate such as age and gender of the patient, poor native vessel structure, medications and the level of surgical experience, 30-40% of new AVFs fail to mature for unknown reasons. For an AVF to become functionally mature postoperative, remodelling and dilation of the native artery and vein are essential to accommodate significantly increased blood flow. However, pre-existing diseases in patients with ESRD such as arterial stiffness and endothelial dysfunction may impair AVF and preclude dialysis. It has been asserted that the lack of AVF success is attributable to insufficient arterial dilation because of poor arterial wall elasticity. The study aims to investigate the role of arterial stiffness and endothelial dysfunction in predicting AVF outcome using novel non-invasive ultrasound applications: 2D shear wave elastography and 2D strain speckle tracking will be employed to assess arterial stiffness, while an intraoperative flow-mediated dilation (FMD) technique will be used to evaluate endothelial dysfunction.

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