What is Arterio-Venous Access?
The purpose of an arterio-venous access is to allow dialysis access. Dialysis machines draw blood from your body, filter it and return the blood back to your body. In order to accomplish this, the flow of blood through the machine must be of a certain speed. Only arteries and certain very large veins in your body can provide the amount of blood flow per second required for dialysis. The problem arises because these arteries and very large veins reside deep in your body and are difficult to access on a regular and safe basis. The goal of surgery is to bring these deep sources to just beneath your skin to allow dialysis.
Currently there are three options available: dialysis catheters, arterio-venous grafts and arterio-venous fistulas. Dialysis Catheters: Dialysis catheters are essentially very large IVs that reside in the deep veins in your body. They are either temporary or permanent. The temporary catheters stick out from the side of your neck, and are not recommended to be used for more than 30 days without replacement. The permanent dialysis catheters also reside in the deep veins in your body but exit from the front of your chest. They are called permanent but are often complicated by infection or other catheter problems. These catheters seldom last for more than a few months without replacement.
Pros: immediately usable, no need to puncture the skin to start the dialysis
Cons: difficult to maintain without infection, when infected requires complete removal and prolonged antibiotics, frequent malfunctioning requiring further procedures, cannot shower/swim with the catheter, the catheter may cause damage to the veins over the long-term.
AV Grafts: The surgeon connects a graft made of synthetic materials to your artery and your large deep vein, and places the graft just beneath your skin. Common locations for the graft are your forearm, your upper arm, and rarely, your thigh. Grafts are relatively easy to place and usually require only one operation. Grafts also can be used earlier (2-4 weeks) after operation as compared to fistulas (6 weeks or more). However, compared to fistulas (see below), grafts more frequently are complicated by infections and they do not stay open as long as fistulas.
Pros: shorter time required for “maturation”, usually requires only one operation
Cons: does not last as long, more prone to infections, when infected requires complete removal and prolonged antibiotics, may require declottings and other secondary procedures over the course of its usable life.
AV Fistulas: Fistulas are currently the best option for dialysis as determined by the Kidney Dialysis Outcomes Quality Initiative (K-DOQI) published by the National Kidney Foundation. A AV fistula (aka dialysis fistula) is created when the surgeon connects your artery to your own superficial vein. No foreign synthetic material is used. Fistulas have been demonstrated to have the lowest rate of complications and tend to stay open the longest. However, because different patients have veins of different quality, and many superficial veins have been used in the past for IV access, fistulas are a bit more difficult to get started. We are asking the vein to essentially function like an artery, and different veins respond differently. Some fistulas may require more than one operation to become functional. Furthermore, fistulas require 6-12 weeks of maturation prior to being accessed for dialysis. However, once started, fistulas have been shown to stay open the longest and are more complication-free compared to grafts.
Pros: best long term patency, lowest rate of infection, no foreign material used
Cons: requires a longer “maturation” time (6 weeks or more), may require more than one operations to create a functional dialysis fistula
Who needs it?
Depending on the degree of your renal failure, we offer different surgical access options to best tailor to your needs.
If you need urgent dialysis, a catheter can be used immediately after it’s placed. Either the temporary or permanent type of catheter may be used, depending on the situation, to bridge the time required for a graft or dialysis fistula to mature.
Pending renal failure but not requiring dialysis:
If you are not yet on dialysis but your nephrologists expects your kidneys to fail in the near future, you should be referred to a vascular surgeon as soon as possible for the creation of a fistula. Because it can take 6-12 weeks to get a dialysis fistula to work, you should be evaluated and the process of fistula creation should begin at least 3-4 months prior to the start of dialysis. This will allow you to avoid having to receive a catheter completely.
What is involved before the operation?
Consultation and physical examination:
When you come to be evaluated at CVTSA for dialysis access, you will meet with our fellowship trained vascular specialists who believe in the fistula-first initiative by the National Kidney Foundation. You will be questioned about the cause of your kidney failure as well as your complete medical history and a detailed examination for your arterial pulses and venous anatomy will be conducted. We will also tailor our recommendations to your work and lifestyle.
Duplex ultrasound vein mapping:
When your arm veins are not easily visible, you will be referred to our nationally-accredited vascular laboratory for a detailed vein mapping with the ultrasound machine. This test is non-invasive and there is no discomfort to you. Many surgeons quickly jump to arterio-evnous graft placement when no superficial veins are visible. We believe that a, AV fistula is so much better than other options that it is worth the effort to use the ultrasound to discover those hidden veins. In fact we find that many patients have excellent veins that are a bit too deep to be seen by routine physical examination alone. At CVTSA we are able to create an AV fistula in about 85% of the patients we encounter, which is a much higher rate than the 60% goal set forth by the National Kidney Foundation guidelines.
Infrequently we may recommend a venogram after the ultrasound study to further study the details of your venous anatomy. This test requires the placement of an IV in your hand and taking pictures undera x-ray machine while injecting contrast into your veins. Because this test is invasive, we reserve it only if further information is required after the ultrasound test.
The 24 hours before the operation:
As with any surgical procedure requiring sedation or anesthesia, you will be asked not to eat or drink anything after midnight. In case general anesthesia is required, the empty stomach will make it safer to control your airway and place you on the ventilator. The exception may be a small sip of water to take your important medications. Please ask your surgeon for details.
Because patients with kidney failure tend to have trouble excreting potassium, we will check your potassium level and conduct a 12-lead EKG (electrocardiogram) the morning of your surgery. Potassium is an important electrolyte that may affect the function of your heart. Therefore, if your potassium level is too high we may decide that it’s safer to postpone the surgery for another time.
Details of the operation
To safely place the catheter, we will use real-time ultrasound to precisely image your large veins deep in your neck. Once we access your vein with the needle, we will use guide-wires under live X-ray to insert the catheter. You will be sedated by the anesthesiologist and the surgeon will supplement the sedation with numbing medication (lidocaine) injected in the area of operation. After the procedure is finished, you will be transferred to a recovery room where another chest X-ray will be performed. Once we confirm that the line is in a good position and that there are no complications with the procedure, you will be discharged home after you have recovered sufficiently from the sedation.
AV graft placement:
For most patients, sedation and local injection of lidocaine will be the anesthesia technique of choice. For others, general anesthesia or laryngeal mask will be used (be “put asleep”). The artery and a large vein will be exposed through either one or two incisions, and a synthetic graft will be connected one end to the artery and the other end to the vein, either in a gentle-curved (“C”) or looped (“U”) configuration. The graft will be directly underneath the skin, and reside either in the forearm or in the upper arm. In certain select cases, the artery and vein from your groin will be used, and the graft will reside in your thigh. Please ask your surgeon about the reasoning behind each specific choice of graft location and configuration.
AV fistula creation:
When the superficial vein is large enough, the surgeon will connect a nearby artery to the vein through one small incision under local injection of lidocaine. This connection will vary in location, depending on the size of your specific veins at different locations on your arm. When the basilic vein is the vein of choice, the creation is usually in two stages. First the surgeon connects a nearby artery to the basilic vein and waits for it to mature in about 6 weeks. If the AV fistula matures and becomes large enough, then the second stage brings the basilic vein closer to the surface to allow easier access by the dialysis nurses. The basilic vein is usually quite deep and will need to be transposed to a subcutaneous location in the majority of patients.
What can you expect afterwards?
Caring for your incision:
For most, the dressing can be removed after 48 hours. Underneath the dressing you will find strips of tape called steri-strips, or “butterfly” strips. You should leave the strips on the wound. You can go ahead and shower and get the wound wet after 48 hours, and pat the area dry afterwards. Do not soak the wound in a bath or in the swimming pool. Keep the wound out of sunlight to prevent darkening of the scar. You should avoid applying creams such as vitamin E creams or others, because they may cause some skin maceration.
You should keep the catheter dry. If you must shower, you should use tape or Saran Wrap to keep the area completely dry. No swimming and no bathing. Avoid having the catheter get caught in your clothing or purse or other locations. Usually your dialysis nurse will take pains to dress the catheter properly – only the dialysis nurse should remove the dressing at the next dialysis session.
For both an AV graft and an AV fistula, the goal is to have it develop such that a “thrill” or a buzzing vibration, is felt at all times. It may take a variable amount of time to develop such a buzz, and is generally longer for an AV fistula. Don’t be alarmed if during the first initial week your graft develops some redness along the graft. If the redness is limited to just the graft and you do not have a fever or notice foul drainage from the incisions, it may be a normal reaction by your body to the foreign material. If you have any doubts, please contact our office. It is highly unusual to have infection complications within the first two weeks of surgery.
Things to watch for and call your doctor about
On the incision:
Call your doctor if you notice redness and swelling around the incision, or observe drainage from the incision. These are the basic signs of wound infection, but your doctor usually needs to look at the wound to make the determination. If you have a fever of greater than 100.5 degrees you should call your doctor.
About the hand:
Because all fistulas and grafts divert blood away from the hand of the same side, you should know the warning signs for hand ischemia, which is the hand not getting enough blood. All patients should exercise their hand by squeezing a ball in their hand as much as possible throughout the day. This will train your hand to tolerate a lower level of blood supply. An early sign is that the hand feels cooler, and occasionally becomes numb. It becomes much more concerning when the hand is numb all the time, and it may be an emergency if the hand is painful or changes color. Seek immediate medical attention if you have these symptoms.
Feeling for the buzz:
The dialysis fistula and the graft will both develop a “buzzing” sensation when they become matured. It usually takes a longer period for the dialysis fistula to develop a buzz, or thrill. If in the initial period after the operation you do not feel a buzzing sensation, you can ask your dialysis nurse or other health care provider to listen to the dialysis fistula/graft with a stethoscope. They should be able to hear the blood flow through the fistula or graft. Call your surgeon if you do not feel the buzz and do not hear any noise over your fistula/graft.
With locations throughout northern Virginia CVTSA proudly serves patients needing dialysis access options in the Virginia, Maryland, and DC area.