Definition & Overview
The kidneys filter blood to remove toxins that can otherwise cause serious harm to the body. Unfortunately, being exposed to toxins makes the kidneys prone to getting damaged. The organs' ability to function properly can also be affected by certain medical conditions including but not limited to type 1 and 2 diabetes, polycystic kidney disease, and urinary tract obstruction. If not corrected, the condition can progress to end-stage renal failure wherein the kidneys stop working well enough to effectively filter the blood.
Severe kidney damage is irreversible but a blood filtering procedure, called dialysis, can reduce its symptoms. Also referred to as renal replacement therapy, this treatment substitutes the natural work of the kidneys. It is an artificial way of eliminating waste and unwanted water from the blood. However, it has certain limitations. Although it keeps waste products in the blood from reaching hazardous levels, it cannot perform other kidney-specific functions such as regulating the body’s water level and secreting certain products that are important for a person’s metabolism.
There are a couple of methods in which dialysis is performed including peritoneal dialysis and hemodialysis. In hemodialysis, a special filter called an artificial kidney (dialyzer) and a dialysis machine are used to clean the blood. This method involves redirecting the patient’s blood flow to a dialysis machine where the blood is filtered before being returned to the body. Blood is obtained from a vein and returned through an artery.
For a patient to undergo hemodialysis, a catheter can be inserted into the large vein either in the chest or in the neck. However, this is usually a short-term option. A long-term and the preferred option is the creation of arteriovenous shunt in a procedure commonly referred to as AV fistula surgery. The creation of AV fistula makes the process of removing blood from the body, filtering it using a dialysis machine, and returning it to the body for as long as the patient lives possible. Doctors also prefer this method because it has low rates of complications, infection, and clotting when compared to using catheter making it the gold standard of vascular access.
Who Should Undergo & Expected Results
AV fistula creation for dialysis is for patients suffering from end-stage renal failure or those whose kidneys have lost the ability to effectively filter their blood. These patients are those who are waiting for a kidney transplant or do not qualify for the transplant procedure usually due to their overall health condition.
The creation of a dialysis fistula offers more benefits when compared to using a catheter. It provides good blood flow for dialysis, is less likely to cause blood clots, it lasts longer than other types of access, and has a significantly lower risk of getting infected. Once the fistula is created, it becomes a natural part of the body. But patients have to wait at least two months for it to be used. It takes up to three months for the fistula to mature, which is crucial for it to provide access with good blood flow that can last for decades. At the start of a hemodialysis treatment, two needles are inserted into the vascular access – one that carries blood from the body to the dialyzer and one that brings filtered blood back to the body.
The procedure is considered safe. But just like any other medical procedures, there are possibilities of complications.
How Does the Procedure Work?
The creation of an AV fistula for dialysis is a quick, outpatient procedure performed by a vascular surgeon. However, in some cases, patients may need to be hospitalised for close monitoring. Before the fistula is created, a specially trained technician will first conduct a vessel-mapping test through a Doppler ultrasound to evaluate the blood vessel that will be used for the procedure. The results of the test are interpreted by a radiologist who then helps the vascular surgeon in choosing the best blood vessels to use based on how much and how quickly blood flows through the arteries and veins. The vascular surgeon then creates a connection between the chosen vein and the nearest artery. If the creation of the hemodialysis fistula procedure goes well, the fistula can be expected to mature within two to three months before it can be used for dialysis. If it fails to mature, the procedure is repeated.
Possible Risks & Complications
A fistula surgery is relatively safe, especially if performed by a highly qualified vascular surgeon. However, there are associated risks and possibilities of complications. These include the risk of developing an infection while the patient is recovering at home. If this happens, the patient should seek immediate medical attention to control the infection and prevent it from spreading throughout the body.
Also, since the procedure involves connecting blood vessels, there is also a possibility that a clot may develop and block the fistula. Blood clots can be dangerous as they may become dislodged and travel to the heart or brain where they can cause significant, life-threatening damage.
Other possible complications include the weakening of the artery or vein (aneurysm) and bleeding in the area where the fistula was created.
Santoro D, Benedetto F, Mondello P, Pipitò N, Barillà D, Spinelli F, et al. Vascular access for hemodialysis: current perspectives. Int J Nephrol Renovasc Dis. 2014. 7:281-94.
Al-Jaishi AA, Oliver MJ, Thomas SM, Lok CE, Zhang JC, Garg AX, et al. Patency rates of the arteriovenous fistula for hemodialysis: a systematic review and meta-analysis. Am J Kidney Dis. 2014 Mar. 63 (3):464-78.