**1. Introduction**

Hemodialysis is the most common modality of dialysis worldwide for patients with end-stage kidney disease (ESKD). In the US, approximately 786,000 patients have ESKD, and 71% of these patients are on dialysis, while 29% have received a kidney transplant [1]. Optimal vascular access is essential for hemodialysis to achieve adequate blood flow rates and maintain patency, while minimizing the risk of complications such as infection and thrombosis.

The most common options for vascular access for hemodialysis are central venous catheters (CVCs), arteriovenous fistulas (AVFs), and arteriovenous grafts (AVGs). AVFs are generally preferred over CVCs due to lower complications overall, reliable blood flow rates, and reduced need for corrective procedures. In those with tunneled CVCs, the likelihood of catheter-related bacteremia is 35% at 3 months and 48% at 6 months [2]. Patients with CVCs experience 4.6 catheter-related bacteremia episodes/1000 catheter-days [2]. Furthermore, up to 40% of catheter-related bloodstream infections lead to further complications such as osteomyelitis and endocarditis [3]. In a study of 865 dialysis patients, catheter dysfunction occurred at a rate of 10.58 episodes/1000 catheter-days and affected 56.65% of patients [4]. Other known risks of CVCs include catheter lumen thrombosis and central venous stenosis [2]. Compared to AVFs, CVCs have shown to have higher infection-related deaths

(RR = 2.30, p < 0.05), higher cardiac-related deaths (RR = 1.47, p < 0.05), and higher overall mortality risk (RR = 1.54, p < 0.05) [5]. Despite the plethora of evidence of AVFs demonstrating better outcomes compared to CVCs, certain vulnerable populations, like those receiving emergency-only hemodialysis (EOHD), are less likely to start their first dialysis with an AVF compared to standard hemodialysis patients [6]. This suggests that there are barriers to receiving timely optimal vascular access, and many would benefit from innovations in hemodialysis access.

The possibility of converting AVF creation from a mainstream surgical procedure to a mainstream interventional procedure holds promise for improving access for patients with CVCs in need of AVFs. This chapter will examine innovations in hemodialysis access as it pertains to CVCs, AVFs, and AVGs.
