When the lifeline for dialysis patients becomes blocked, immediate intervention can mean the difference between continuing treatment and facing serious complications. Arteriovenous graft thrombosis is a common and serious problem that affects thousands of people who depend on hemodialysis to survive.

Understanding the Challenge of Maintaining Dialysis Access

For more than 400,000 people in the United States who rely on hemodialysis, maintaining a functioning access point is essential for survival. An arteriovenous graft, or AVG, is a synthetic tube surgically placed to connect an artery and a vein, creating a high-flow blood vessel that allows dialysis machines to remove waste from the body when kidneys no longer function properly. However, these lifesaving connections face a persistent threat: blood clots that can block the graft and prevent dialysis from being performed.^[5][12]

The main goal of treating arteriovenous graft thrombosis is to restore blood flow through the access so that dialysis can continue. Treatment approaches depend on how quickly the blockage is detected, the patient’s overall health, and whether there are underlying problems with the blood vessels. Medical teams work to balance immediate clot removal with long-term strategies to prevent future blockages. Standard treatments approved by medical societies exist alongside ongoing research into new approaches, including innovative techniques being tested in clinical settings.^[4]

When an arteriovenous graft becomes blocked by a blood clot, patients may miss multiple dialysis sessions, require hospital admission, and need temporary dialysis catheters inserted into large veins. These temporary catheters carry higher risks of infection and can cause damage to the veins themselves. Thrombosis, the medical term for blood clot formation, accounts for approximately 65 to 85 percent of all cases where dialysis access is permanently lost. For grafts specifically, thrombosis occurs roughly 0.5 to 2.0 times per year for each patient, making it a recurring challenge in dialysis care.^[5][12]

Prevention: The First Line of Defense

The most effective treatment for arteriovenous graft thrombosis is preventing it from happening in the first place. Regular monitoring allows healthcare providers to identify warning signs before a complete blockage occurs. This monitoring involves a combination of physical examination techniques and review of data collected during routine dialysis sessions. Healthcare professionals use a simple approach called “look, feel, and listen” to detect problems early.^[8][12]

During physical examination, which should occur at least monthly, trained practitioners carefully assess the graft by observing, touching, and listening to it. When touching the graft, they should feel a vibration called a thrill, which indicates blood is flowing properly. If this sensation changes or disappears, it may signal a developing problem. Using a stethoscope, healthcare providers listen for a whooshing sound called a bruit. Changes in this sound—such as becoming high-pitched or losing certain components—can indicate narrowing of the blood vessel.^[8][12]

Signs of problems in the outflow vein (where blood exits the graft) include bulging or balloon-like swelling of the access, unusually strong pulsing, an interrupted vibration, and a high-pitched sound. Signs of problems with blood flow coming into the graft include a flattened appearance of the fistula, poor firmness when touched, or a weak sound. Dialysis data such as pump pressures, prolonged bleeding after needle removal, and measurements of dialysis effectiveness also provide valuable clues about potential blockages forming.^[8][12]

The effectiveness of monitoring and surveillance programs in actually preventing thrombosis and extending the life of the access remains somewhat uncertain according to research studies. However, detecting narrowing or stenosis in the blood vessels before complete blockage occurs allows for intervention that may prevent thrombosis. Some centers use ultrasound imaging to evaluate grafts that show clinical signs of dysfunction, which may provide benefits for maintaining access patency, though routine ultrasound screening in patients without symptoms is not currently standard practice.^[5][12]

Standard Treatment Approaches for Stenosis

Stenosis, the narrowing of blood vessels, is the number one cause of arteriovenous graft dysfunction and the leading factor contributing to thrombosis. Evidence suggests that stenosis causes 78 percent of all cases of early graft failure and is also the most common cause of late graft failure occurring after three months of use. This narrowing typically develops gradually as the body responds to the surgical connection between artery and vein.^[4][17]

When an artery and vein are connected, the vein experiences a dramatic change. It must suddenly handle the high pressure and fast blood flow that normally exists only in arteries. This stress can damage the inner lining of the vein. The body attempts to repair this damage by sending extra cells to the injured area, but over time these cells accumulate and narrow the blood vessel. This process, called intimal hyperplasia, involves thickening of the innermost layer of the vein and is a primary cause of stenosis.^[17]

The standard treatment for stenosis without complete blockage is angioplasty, also known as percutaneous transluminal angioplasty or PTA. This procedure uses imaging guidance to position a catheter with a balloon at its tip inside the narrowed section of the graft or vein. When the balloon is inflated, it stretches the narrowed area, restoring a wider channel for blood flow. This minimally invasive procedure can often be performed in an outpatient setting using local anesthesia, meaning patients can typically go home the same day.^[3][9]

If angioplasty alone does not successfully maintain an open channel, doctors may place a stent—a small wire mesh tube—inside the blood vessel to hold it open. The stent remains permanently in place, providing structural support to prevent the vessel from narrowing again. However, stents are not always used as the first choice, and doctors carefully evaluate whether they are necessary based on the specific situation and location of the narrowing.^[3][9]

The success of angioplasty depends on many factors including the location of the narrowing, whether it has occurred before, and the overall quality of the patient’s blood vessels. Repeated treatments may be needed over time as stenosis can recur. Clinical guidelines from nephrology societies recommend monitoring access function and intervening when decreased blood flow is detected, even before complete blockage occurs. The timing and frequency of interventions are individualized based on each patient’s specific circumstances and how well their access performs during dialysis.^[4]

Standard Treatment for Complete Blockage

When a blood clot completely blocks an arteriovenous graft, immediate treatment is needed to restore flow and allow dialysis to continue. Historically, surgical removal of the clot was the standard approach, but over the past several decades, techniques performed through the skin using image guidance have become increasingly common. These percutaneous methods, meaning “through the skin,” generally cause less trauma to surrounding tissues and often allow faster recovery compared to open surgery.^[6][11]

Several percutaneous approaches exist for removing clots from dialysis grafts. One method is catheter-directed thrombolysis, which involves injecting clot-dissolving medications directly into the blocked graft through a catheter. These medications, called thrombolytics, work by breaking down the proteins that hold the clot together, essentially dissolving it over time. The “lyse-and-wait” technique involves injecting the medication and allowing it to work for a period before checking if the clot has dissolved.^[3][9]

Another approach is mechanical thrombectomy, where specialized devices are inserted through a catheter to physically remove or break up the clot. Some devices work by mashing up the clot into tiny pieces that can flow away in the bloodstream. Others use suction to pull the clot out of the body entirely, a technique called thromboaspiration. Many interventionalists use combination approaches, such as pulse spray aided pharmacomechanical thrombolysis, which combines clot-dissolving medication with mechanical disruption of the clot for more effective removal.^[5][9][12]

After the clot is removed, doctors typically perform angiography—an imaging study using contrast dye—to examine the entire graft and connected blood vessels. This helps identify the underlying cause of the thrombosis, which is most often stenosis. If stenosis is found, it is usually treated immediately with angioplasty and possibly stent placement to reduce the risk of the graft clotting again. Without treating the underlying stenosis, the graft is likely to develop another clot soon after the initial clot is removed.^[5]

Surgical thrombectomy remains an option in certain situations. The surgical procedure involves making an incision over the graft, inserting a special catheter called an embolectomy catheter, and using it to pull clots from both the venous and arterial sides of the graft. This approach requires general anesthesia, which can be risky for dialysis patients who often have multiple medical conditions. Recent studies comparing surgical and endovascular (through-the-blood-vessel) treatments show mixed results regarding which approach provides better long-term patency, though endovascular methods have somewhat higher technical failure rates initially.^[8][13]

The choice between percutaneous and surgical treatment depends on multiple factors including the expertise available at the treatment center, the patient’s overall health and ability to tolerate anesthesia, how long the graft has been clotted, and whether the patient has had previous interventions. In general, if percutaneous options are available and the patient is a suitable candidate, these are often tried first due to their less invasive nature.^[8]

Preparing for Treatment

Before undergoing treatment for a blocked or narrowed graft, patients need to provide their healthcare team with important information. You should tell your doctor about all medications you take, including herbal supplements and over-the-counter drugs. Certain medications that affect blood clotting, such as aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs like ibuprofen), and blood thinners, may need to be temporarily stopped several days before the procedure. However, never stop taking prescribed medications without explicit instructions from your doctor.^[3][9]

It is essential to inform your healthcare team about any allergies you have, particularly allergies to local anesthetics, general anesthesia, or contrast materials (the special dye used in imaging studies). Tell your doctor about recent illnesses or other medical conditions that might affect the procedure or recovery. Women should always inform their doctor if there is any possibility of pregnancy, as radiation used in imaging can potentially harm a developing fetus.^[3][9]

Most percutaneous procedures for graft thrombosis are performed on an outpatient basis, meaning you can go home the same day. Your doctor will provide specific instructions about eating and drinking before the procedure. You will be asked to wear a hospital gown and should leave jewelry and valuables at home. Someone should plan to drive you home after the procedure, as you may receive sedation that makes driving unsafe.^[3][9]

What to Expect During and After Treatment

During percutaneous treatment, you will lie on a procedure table while imaging equipment helps guide the physician. The skin over the access point is cleaned and numbed with local anesthetic, so you should only feel pressure rather than pain when the catheter is inserted. Depending on the procedure, you may also receive sedation medication to help you relax. The procedure typically takes one to several hours depending on the complexity of the blockage and whether additional treatments like angioplasty are needed.^[3][9]

After the procedure, pressure is applied to the puncture site to prevent bleeding. You will be monitored for a period to ensure the graft is functioning properly and that you are not experiencing complications. Most patients can return to dialysis within a day or two after successful treatment. Your healthcare team will check that blood is flowing properly through the graft by feeling for the characteristic thrill and listening with a stethoscope for the normal sounds of blood flow.^[6]

Complications from percutaneous procedures can occur but are generally uncommon. Potential risks include bleeding from the puncture site, infection, damage to blood vessels, allergic reactions to contrast dye or medications, and failure to successfully remove the clot. In some cases, pieces of clot may travel to other parts of the body, though techniques used during the procedure are designed to minimize this risk. Surgical procedures carry similar risks plus those associated with general anesthesia and a larger incision.^[3][9]

After treatment, it is important to protect your graft. Avoid lying on or sleeping on the arm with the access. Do not lift anything heavier than about 7 kilograms (15 pounds) with that arm. This means avoiding heavy grocery bags, vacuum cleaners, or lifting children. You can shower but should keep the access site dry for the first two days by covering it with a waterproof covering. Avoid activities that put stress on the arm such as heavy gardening or washing windows.^[19]

Long-Term Outlook and Repeat Treatments

Even after successful treatment of thrombosis or stenosis, arteriovenous grafts remain at risk for developing problems again. The long-term function of a graft is measured using concepts called primary patency and secondary patency. Primary patency refers to how long the graft remains open without needing any intervention. Secondary patency, which is generally higher, refers to how long the graft can be kept functioning with interventions such as angioplasty or thrombectomy.^[4]

Data on patency after treatment varies depending on many factors including the initial cause of the problem, the patient’s blood vessel quality, and how well the access is maintained. Studies examining outcomes after endovascular treatment of blocked grafts show that many patients require repeated interventions over time. Some research comparing surgical and endovascular approaches found similar short-term success rates, but higher rates of problems returning after one to two years with endovascular therapy compared to surgical revision.^[8][13]

The multidisciplinary management of dialysis access—with coordinated care among interventional radiologists, vascular surgeons, and nephrologists—has proven extremely effective in prolonging access life and reducing complications for patients with chronic kidney failure. Over the past several decades, the role of interventional radiologists has evolved from simply diagnosing problems to actively treating patients in partnership with other specialists. This team approach helps maximize the functional life of each access, which is crucial since patients may need dialysis for many years.^[6][11]

Because grafts and fistulas can develop problems repeatedly, ongoing vigilance is essential. Regular physical examination during dialysis sessions, monitoring of dialysis parameters, and prompt investigation of any changes help catch problems early. When stenosis is detected and treated before complete thrombosis occurs, outcomes are generally better than when treating a completely blocked access. This is why many programs emphasize preventive intervention when monitoring detects decreasing function.^[4][12]

Innovations and Emerging Approaches

The treatment of arteriovenous graft thrombosis and stenosis continues to evolve with ongoing research into new techniques and technologies. The medical device industry has developed increasingly sophisticated mechanical thrombectomy devices designed to remove clots more quickly and completely. These devices use various mechanisms including rotation, suction, and mechanical fragmentation to break up and remove clots. As these devices improve, percutaneous treatment success rates may continue to increase.^[6][11]

Research is also exploring ways to reduce stenosis formation in the first place. Scientists study the biological processes that lead to intimal hyperplasia—the thickening of blood vessel walls that causes narrowing. Understanding these processes at the molecular level may eventually lead to new preventive treatments. Some research examines whether certain medications or coatings applied to grafts might reduce the body’s reactive tissue buildup.^[1]

Computational studies using computer modeling have investigated how the angle at which the graft connects to the vein affects blood flow patterns. These studies suggest that the anastomotic angle—the angle of connection—influences areas of abnormal blood flow that may contribute to stenosis development. Research indicates that very shallow angles (less than 20 degrees) and very steep angles (greater than 40 degrees) may create more problematic flow patterns, while intermediate angles around 30 degrees might be optimal. Such findings could eventually influence surgical techniques for creating grafts.^[1][20]

The quality of the blood vessels used for creating access significantly affects long-term success. Preoperative evaluation has become more sophisticated, with ultrasound mapping used to assess blood vessel size and quality before surgery. Surgeons can measure artery diameter, vein diameter, and blood flow characteristics to select the best possible vessels for access creation. When vessels do not meet ideal criteria, alternative sites or types of access may be chosen. This careful planning helps reduce early failure rates.^[1]

Research continues into optimal surveillance strategies. While the benefit of routine surveillance in preventing thrombosis remains debated, studies are examining which monitoring methods provide the most useful information. Some research looks at measuring blood flow rates through the access using ultrasound or other techniques. Other studies evaluate whether certain patterns of change in dialysis parameters can predict which accesses are most likely to develop problems soon.^[5][12]

Most common treatment methods

• Monitoring and Surveillance
  • Monthly physical examination using look, feel, and listen approach to detect stenosis before thrombosis occurs
  • Assessment of graft for presence of thrill (vibration) and bruit (sound) indicating proper blood flow
  • Review of dialysis parameters such as pump pressures, bleeding time, and adequacy measurements
  • Ultrasound imaging in selected cases to evaluate for narrowing when clinical signs of dysfunction are present
• Angioplasty (Percutaneous Transluminal Angioplasty)
  • Balloon dilation of narrowed sections of graft or connected blood vessels to restore blood flow
  • Performed using image guidance with local anesthesia, typically as outpatient procedure
  • Standard treatment for stenosis when decreased flow is detected before complete blockage
  • May be combined with stent placement if balloon dilation alone does not maintain vessel opening
• Percutaneous Thrombectomy
  • Catheter-directed thrombolysis using clot-dissolving medications injected directly into blocked graft
  • Mechanical thrombectomy using devices to physically break up or remove clots
  • Thromboaspiration using suction to extract clot material from graft
  • Pulse spray aided pharmacomechanical thrombolysis combining medication with mechanical disruption
  • Typically followed by angioplasty to treat underlying stenosis that caused thrombosis
• Vascular Stenting
  • Placement of wire mesh tube inside blood vessel to hold it open when angioplasty alone fails
  • Stent remains permanently in place providing structural support
  • Used selectively based on location and characteristics of stenosis
• Surgical Thrombectomy and Revision
  • Open surgical procedure to remove clots using embolectomy catheter
  • Requires general anesthesia and larger incision compared to percutaneous methods
  • May include surgical revision of graft or anastomosis to correct underlying problems
  • Reserved for cases where percutaneous approaches fail or are not suitable