Comparison of Tree Types of Distal Arteriovenous Fistulas: Snuffbox Fistula (SBAVF), Radiocephalic Fistula (RCAVF) and RCAVF With Venous Branch Patch.

Research Project Objectives An important aspect in maintaining hemodialysis therapy is an optimal vascular access (AV) in patients with end-stage renal disease (ESRD). The radiocephalic arteriovenous (RCAVF), at the level of the wrist, or snuffbox fistula SBAVF stands out as the preferred vascular access (VA) for hemodialysis, due to its lower risk of infection and mortality compared to alternative options. The inherent properties of AVFs contributes not only to improved patient's safety but also to more efficient hemodialysis procedures. Despite this, AVFs has two disadvantages: a high early failure rate, occurring within one month after access creation, and a high failure rate during a maturation. Early failure rates differ between groups, ranging from 2-23% in brachiocephalic AVF (BCAVF) to up to 5-46%, in RCAVFs.[1] In the Jemcow study , a fistula was defined as mature when blood flow was greater than 500 ml/min and diameter of the cephalic vein exceeded 5 mm. Depending on when AVFs attained maturity, 53% of patients had successful AVF maturation, 36% had prolonged maturation i.e., within eight weeks, and 11% of AVFs failed to mature. Female sex, older patients, poor upper extremity vessels, distal placements and accesses with smaller diameter artery and vein are risk factors for failure to mature.

Despite advances in surgical techniques and perioperative care, fistula maturation remains a challenging part of hemodialysis access. This was shown by Bylsma et al., who conducted a meta-analysis that raised doubt on the AVF's utility in addressing ESRD.3 They evaluated the outcomes of more than 60.000 AVF access formations and found 1-year primary, primary assisted, and secondary patency rates of 64%, 73%, and 79%, respectively. However, only 26% of created fistulas were reported as mature at 6 months and 21% of fistulas were abandoned without use. In another meta-analysis study by Al-Jaishi, based on 37 studies, the risk of primary failure was 23% and primary patency rate was 60% at 1 year and 51% at 2 years.4 Clinical fistula maturation is the result of a crucial process in establishing functional VA for hemodialysis patients. It refers to the formation of a mature, useable AVF supplying the necessary blood volume for efficient dialysis. Data from a multicentre perspective cohort study by Robbin et al. of 602 patients who received a new single-stage AVF, demonstrated that unassisted and overall AVF clinical maturation can be predicted by three ultrasound parameters, fistula blood flow, diameter and depth. Performing such assessment, 6 weeks after surgery, provides valuable guidance regarding early intervention to facilitate maturation (e.g., percutaneous angioplasty or early planning of a second anastomosis) may increase maturation/utilization of the fistula and reduce exposure to central venous catheters.

The study will enroll individuals with and chronic kidney disease (CKD) in stage G4 and G5 including hemodialysis (HD) patients.

Clinical practice guidelines recommend distal arteriovenous fistula (AVF) RCAVF or SBAVF, rather than proximal arteriovenous anastomosis involving the brachial artery due to high risk of hemodialysis access hand ischemia and high flow heart failure. There have been no studies comparing the three aforementioned distal anastomosis in a single project.

Research hypothesis: There are differences between various types of AVF with regard to of early and late patency rates. The investigators also suppose that the type of AVFs may influence the postoperative increase in arteriovenous fistula diameter, blood flow, and, finally, AVF maturation.