Av Fistula

An arteriovenous fistula is a link or channel between an artery and a vein that is aberrant. It can be congenital, surgically produced for hemodialysis treatments, or acquired due to pathologic events like trauma or an artery aneurysm erosion.

An arteriovenous fistula is a link between an artery and a vein that is abnormal. Your blood transports nutrients and oxygen from your capillaries to your body’s tissues. It goes straight from an artery into a vein through an arteriovenous fistula, skipping specific capillaries. The tissues below the skipped capillaries receive less blood as a result.

Arteriovenous fistulas are most commonly found in the arms. However, they can appear elsewhere on the body. In individuals with severe renal disease, arteriovenous fistulas are frequently surgically constructed for use in dialysis.

An extensive arteriovenous fistula that is left untreated might cause significant consequences. If you’re on dialysis, your nephrologist will keep an eye on your arteriovenous fistula.

If you’ve been diagnosed with ESRD and need dialysis, you’ll need dialysis access implanted. An AV fistula is the most remarkable kind of dialysis access since it lasts longer and has fewer complications.

What is an AV Fistula? 

A vascular surgeon creates an AV fistula, a surgical connection between an artery and a vein. It is usually found in the arm, although it may also be found in the leg if required. Blood travels directly from the artery into the vein through an AV fistula, boosting blood pressure and blood flow. Veins expand as a result of the increased flow and pressure. The raised veins will be capable of supplying the required blood flow for effective hemodialysis therapy.

AV fistulas are the preferred vascular access for long-term dialysis because they persist longer than any other dialysis access type, are less prone to infection and clotting, and can be depended on for predictable performance.

A surgical link between one of your arteries and one of your veins is known as an AV Fistula. A fistula is usually made in your non-dominant arm, but it can also be made in your leg if your arm’s arteries and veins aren’t large or healthy enough.

Background:

Dialysis is a popular therapy for patients who have low kidney function. A dialysis machine removes toxins from the blood in individuals with end-stage renal or kidney disease, taking over the role of failing kidneys. A patient must first have a surgical operation to provide an access point for the dialysis machine before starting dialysis. Most commonly, this is done in the arm or wrist by joining an artery and a vein. A vascular surgeon, who specializes in treating the circulatory (vascular) system, performs the surgery.

AV fistula: a type of hemodialysis fistula

Hemodialysis fistulas are surgically constructed connections between an extremity’s natural artery and vein. Native arteriovenous fistulas are a type of direct connection (AVFs). Prosthetic hemodialysis access arteriovenous grafts are made of polytetrafluoroethylene (PTFE) and other materials (Dacron, polyurethane, bovine vasculature, saphenous veins) that are used or have been utilized as a communication medium between the artery and the vein (AVGs). Hemodialysis is performed 2–5 times per week using the access that has been established.

The arteriovenous fistula (AVF), arteriovenous fistula graft (AVG), and indwelling central venous catheter (CVC) are the three major hemodialysis access modalities with the lowest mortality, morbidity, and cost. Despite efforts to promote the use of autogenous AVF, hemodialysis is started in 83 percent of patients in the United States with a CVC, compared to just 14 percent with an AVF.

Why is an AV Fistula important?

A fistula is a unique connection formed by connecting a vein to an artery, most often in the arm. It results in a significant, vital blood artery that may be needled for use during hemodialysis regularly.

Haemodialysis removes toxins from your blood by passing it through a machine that cleans it. Blood is removed from your body and filtered before being returned to you. Toxins are transferred from your blood to dialysis fluid, which is subsequently emptied. The fistula allows vast quantities of blood to be processed reliably for hemodialysis.

How is an AV fistula created?

Creating an AV fistula is considered minor surgery and can be done as an outpatient treatment. It generally takes approximately an hour to finish the process. Your fistula is generally made via a minor procedure performed under a local anesthetic, which numbs your skin and makes you feel nothing. 

Some patients will require a general anesthetic, which will put them to sleep. If more major surgery is necessary or you are unlikely to tolerate local anesthesia, this is the situation. If you’re right-handed, your fistula will most likely be developed in your non-dominant arm (the one you don’t write with).  It generally develops at the level of your wrist or elbow. 

The surgeon will make a tiny cut in the skin. By creating a tiny hole between them, the artery that takes blood away from the heart and the vein that delivers blood back to the heart will be connected. Some of the blood in the artery will be diverted to the vein as a result of this. The incision in the skin is closed with stitches. These are typically dissolvable, and after approximately ten days, they will start to fade away on their own. This procedure generally takes approximately an hour to complete.

Will it leave a scar?

Yes. In most cases, the operation will leave a scar. This is because an incision creates the fistula. The scar will usually diminish in appearance over time. The scar is generally about 4cm long.

When is the best time to make an AV Fistula?

Ideally, your renal team will work with you to arrange the development of a fistula before you begin dialysis. It gives the fistula time to grow, so it may be used when you require dialysis. The longer a fistula can grow before being utilized for dialysis, the better it will function and last. As a result, a fistula should be made roughly six months before you need to start dialysis. 

You will meet with a surgeon at the outpatient clinic before being assigned a date for your surgery. The surgeon will go through the procedure with you. They may arrange for further tests to assist in determining the type of fistula you require. An ultrasound examination of your arm is generally performed to determine the size of your arteries and veins.

Recovering from AV fistula creation

The construction of an AV fistula can be done as an outpatient operation without an overnight stay in the hospital. You should be able to return home within a few hours of the procedure being done.

To prevent swelling and pain at the access site, you’ll be told to keep your access arm elevated. Your nephrologist may also prescribe a pain reliever to aid with any postoperative discomfort.

You will be given detailed instructions on how to care for your access before being sent home.

How is an AV fistula used during dialysis?

Patients are linked to a dialysis machine via an AV fistula. Two needles are inserted into the AV fistula by a nurse to begin your dialysis therapy. The blood is removed with one needle and sent to the machine, where it is filtered. The second needle allows the blood to be returned to the body safely. Each dialysis session lasts three to four hours, and most patients require three sessions each week.

When does AV fistula surgery take place?

Approximately six months before the first dialysis session, the procedure is conducted. The AV fistula may take several weeks to mend and become strong enough to tolerate the rigors of dialysis treatments. The high-pressure blood flow from the artery strains the vein walls in the weeks after surgery. The vein enlarges as it extends. As a result, the dialysis nurse has a long-lasting access point to link the patient to the dialysis machine.

Advantages of an AV fistula

Because your AV fistula allows more blood to flow through your vein at a quicker pace, the pressure inside the vein will rise. The vein extends and strengthens due to the increased venous pressure, enabling more blood to travel back and forth from your vein to the dialyzer.

  • It lasts longer than other types of vascular access.
  • No synthetic material is placed in your body, ensuring adequate blood flow for successful dialysis and perhaps reducing treatment duration.
  • Infection risk is minimal.
  • Other dialysis access methods are more prone to clotting.
  • Created during a local anesthetic outpatient treatment
  • Return to your routine as soon as possible.
  • Your own body forms AV fistulas. There are no artificial ingredients in this recipe.
  • They have a long-life span.
  • They’re less prone to develop infection or clogging than a catheter.
  • They’re usually easier to keep up with than other access choices.
  • AV fistulas improve blood flow to the dialyzer and may cut dialysis treatment time in half.

Disadvantages of an AV Fistula

An arteriovenous fistula, like any other dialysis access method, is not without its drawbacks. However, these downsides are minimal compared to the issues frequently linked with other forms of access, such as a central venous catheter (CVC). The following are the primary drawbacks of having an AV fistula:

  • If you require dialysis immediately, you will need a temporary access device that can be utilized until your AV fistula heals and matures.
  • Healing can take longer than planned, or the access may not mature as predicted.
  • To access the AV fistula for dialysis, needles are necessary.

Who Can Get an Arteriovenous Fistula?

If your veins are in good shape and you don’t require dialysis right away, an AV fistula is likely your best option for dialysis access. Even if you need dialysis right away, your nephrologist may recommend that you have an AV fistula established for long-term therapy.

A process called vascular mapping will assess whether or not your veins are healthy and big enough for an AV fistula. It can be done with an ultrasound machine or by injecting contrast dye into your veins while undergoing fluoroscopy (a form of x-ray) to collect and analyze a picture or map of your veins.

AV Fistula Maturation Time

Due to the increased blood flow, the vein grows larger, and its walls thicken and strengthen over time. It is referred to as “maturing.” It usually takes 6-8 weeks to be ready to use after it has been made. Your renal team will continue to monitor your fistula and notify you when it is ready to be utilized. 

You’ll also learn how to feel and hear your fistula so that you can check it for yourself and make sure it’s still working. For a few days after surgery, you may suffer discomfort, swelling, and bruising at your access site. It is very typical. You could also feel a vibration from your access point. It is described as a “thrill,” and it is pretty natural. The excitement will get more robust in the first week after surgery. It takes time for your AV fistula to mature before it can be used. On average, this takes 4.5 months.

AV Fistula Care

  • An arteriovenous fistula must be checked and cared for regularly. You should clean it with antibacterial soap and water every day, and you should avoid sleeping on it. Look for indicators that your AV fistula is working correctly by looking, listening, and feeling for them.
  • Wearing a watch or tight clothes on your fistula arm is not a good idea. 
  • Avoid having your blood pressure or blood tests taken from that arm, and try not to sleep on that side of your body.
  • Your renal team will show you how to check for a pulse or vibration daily (called a thrill) via your fistula. Call your renal team immediately since the fistula might be plugged if you don’t have this sensation.
  • Blood pressure or blood samples should never be obtained from your fistula arm since this increases the risk of fistula damage and clotting.

It’s essential to look after your AV fistula. Your dialysis access is your lifeline to good health. With proper maintenance, once it’s completely grown, you may anticipate your AV fistula to work generally for the rest of your life.

Are there alternatives to AV fistula?

The ideal approach to getting dialysis is through an AV fistula, a long-term option for dialysis patients with minimal risk of infection. However, there are a few more options to consider. AV bypass graft surgery can implant an artificial vein if you don’t have a large enough vein for an AV fistula. If dialysis is needed right away, a dialysis catheter can be placed into a vein until a more long-term solution is found.

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