The need
End-stage kidney disease
End-stage kidney disease (ESKD) is often a result of a combination of problems, such as hypertension and diabetes mellitus, and can be (partially) genetic. As a result ESKD excess fluids and waste in the blood cannot leave a patient’s body and cause serious health problems. Patients with ESKD require a lifesaving modality to replace kidney function and prevent mortality from the accumulation of waste products. Due to a shortage of donor kidneys available for transplant, most patients with ESKD depend on hemodialysis as kidney replacement therapy to stay alive.
Vascular access for hemodialysis
The most common type of dialysis is hemodialysis. Using an ”artificial kidney” called the dialyzer, a patient’s blood is purified and the patient’s excess of water is removed. Critical to the process is a vascular access site where a high blood flow of minimum 600 mL/min needs to be created to circulate the patient’s blood effectively. The high blood flow can be achieved by surgically creating a shunt between a major artery and vein in the arm, which is called an arteriovenous fistula (AVF). The difference in pressure between the artery and vein creates a low resistance pathway for blood that promotes increased flow through these vessels. An AVF is the current golden standard for vascular access. When native vessels are not suitable, an arteriovenous graft (AVG) is used, which utilizes a graft made from synthetic material like polytetrafluoroethylene (PFTE). A central venous catheter (CVC) is often used for temporary access.
Complications
The high-flow vascular access site required for hemodialysis frequently causes serious complications. Among others, complications include:
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- Loss of access patency: luminal narrowing (also called stenosis) of the venous outflow tract near the AVF, ultimately leading to AVF thrombosis, is the main limiting factor for the durability of the AVF
- Heart failure: a continuous AVF causes a decrease in systemic vascular resistance, which results in hyperdynamic circulation with an increased cardiac output, resulting in an additional cardiac burden for these vulnerable patients
- Compression time & risk of bleeding: due to high pressure and flow, patients need to compress for at least 10 minutes after dialysis to avoid bleeding. The risk of bleeding persists, however, once the patient is back home
- Steal syndrome: Peripheral ischemia of the forearm and hand as a result of “stealing” arterial blood flow into the AVF
- Aneurysms: The high turbulent blood flow causes dilatation of the vein of the AVF, which increases the risk of aneurysm formation in the draining vein