To start, here are several definitions (sometimes incorrectly used) dealing with Fistulas and Grafts, followed by a review of Common complications of Vascular Access Devices :

Aneurysm: An abnormal blood-filled dilation of a blood vessel wall (most commonly in arteries) resulting from disease of the vessel wall. Involves all three layers of the wall (intima, media, adventitia).

Pseudoaneurysm: Also known as a false aneurysm, is an outpouching of a blood vessel, involving a defect in the two innermost layers (the tunica intima and media) with continuity of the outermost layer, the adventitia. Alternatively, all three layers are damaged and bleeding outside of the vessel is contained by a clot or by surrounding tissue. Pseudoaneurysms can occasionally result from trauma to the intima of the blood vessel, and are a well known complication of percutaneous arterial punctures (as seen in hemodialysis access.)

Complications of Vascular Access:

Long-term successful HD depends on reliable access to the patient's circulation. In cases in which a native artery or vein are not suitable for AV fistula creation, an interposing vascular graft made of an autologous vein, polytetrafluoroethylene (PTFE), or bovine carotid artery must be used for vascular access. These grafts generally have a higher complication rate and shorter functional life expectancies than do natural AV fistulas. The third form of vascular access for HD is tunnel-cuffed catheters (e.g., Hickman, Neostar, Quinton) placed using a surgically created tunnel. The most common site for tunnel-cuffed catheter placement is the right internal jugular vein. Because of the cuff, these catheters cannot and should not be removed by pulling. Vascular access is the Achilles heel of HD, and complications of the vascular access account for more inpatient hospital days than do any other complication of HD.

Thrombosis

Thrombosis and stenosis of the vascular access site are the most common complications. Grafts generally have a higher rate of stenosis, secondary to endothelial hyperplasia, than do fistulas. Stenosis or thrombosis present with loss of bruit and thrill over the access site. Stenosis and even thrombosis are not always emergencies and may be treated within 24 h by angiographic clot removal or angioplasty (though consultation with a vascular surgeon is warranted). Thrombosis of vascular access can also be treated with direct injection of alteplase 2.2 mg into the access.

Infection

Vascular access infections occur in 2 to 5 percent of AV fistulas and about 10 percent of vascular grafts over their functional lifetime. Patients with an infected access often present with signs of systemic sepsis, such as fever, hypotension, or an elevated white blood cell count. Classic signs of pain, erythema, swelling, and discharge from an infected vascular access are often missing. The most common organism is Staphylococcus aureus, followed by gram-negative bacteria. Patients with access infections usually require hospital admission. Vancomycin is the drug of choice (1 g IV), because of its effectiveness in methicillin-resistant organisms and long half-life (5 to 7 days) in dialysis patients. An aminoglycoside (gentamicin 100 mg IV initially and after each dialysis) is usually added empirically to cover gram-negative organisms.

Hemorrhage

Hemorrhage from a vascular access site can produce life-threatening blood loss. Hemorrhage can result from aneurysms, anastomosis rupture, or over-anticoagulation. Bleeding that requires the patient to come to the emergency department should immediately be controlled with digital pressure at the puncture sites for 5 to 10 min, and the patient should be observed for 1 to 2 h thereafter. Continued or life-threatening hemorrhage may require the placement of a tourniquet proximal to the access. A vascular surgeon should be consulted if bleeding cannot quickly be brought under control. If over-anticoagulation is a concern, the effects of heparin can be reversed by protamine given at a dose of 0.01 mg/units heparin dispensed during dialysis. If the dose of heparin is unknown, protamine, 10 to 20 mg, will be sufficient to reverse heparin, 1000 to 2000 units. If bleeding stops, the patient should be observed for 1 to 2 h for rebleeding or thrombosis. Occasionally, a newly inserted vascular access will continue to ooze at the insertion despite pressure. Small pieces of gelfoam soaked in reconstituted thrombin can be placed onto oozing sites. Desmopressin acetate (0.3 g/kg IV, maximum dose 20 mg) can be administered as an adjunct. If the emergency physician is unfamiliar with the use of desmopressin acetate in this situation, the nephrologist should be consulted.

Aneurysms

Vascular access aneurysms result from repeated puncturing, leading to bulging of the wall. True aneurysms are very rare, occurring in fewer than 4 percent of fistulas or grafts. Most aneurysms are asymptomatic, with patients occasionally complaining of pain or an associated peripheral impingement neuropathy. Aneurysms rarely rupture.

Vascular access pseudoaneurysms result from subcutaneous extravasation of blood from puncture sites. Patients commonly present with bleeding and infections at access sites. Bleeding from the puncture site is usually controlled by digital pressure or a subcutaneous suture carefully placed at the puncture site. Vascular surgery may be required for continued bleeding or infection.


Destruction of PTFE graft material by repeated puncture at one site

Distal Vascular Insult

Vascular insufficiency of the extremity distal to the vascular access occurs in approximately 1 percent of all patients. The named "steal syndrome" is the result of preferential shunting of arterial blood away from nutrient arteries to the low-pressure venous side of the access. Patients frequently present with exercise pain, nonhealing ulcers, and cool, pulseless digits. Steal syndrome is diagnosed by Doppler ultrasound or angiography and is repaired surgically.

High output heart failure

High-output heart failure can occur when greater than 20 percent of the cardiac output is diverted through the access. Branham sign, a drop in heart rate after temporary access occlusion, is useful for detecting this complication. Doppler ultrasound can accurately measure access flow rate and establish the diagnosis. Surgical banding of the access is the treatment of choice to decrease flow and treat heart failure.


Case Outcome:
After vascular surgery consultation, it was determined that our patient had developed a pseudoaneurysm at her AV fistula site, most likely due to repeated use of the fistula and subsequent weakening of the wall. The following week she underwent surgical repair and was doing well.

References:
-Discussion of this case was taken from Tintinalli’s Emergency Medicine.
Sinert, Richard. Spektor, Mark. Tintinalli’s Emergency Medicine, Section 10: Renal and Genitourinary Disorders, Chapter 93. Emergencies in Renal Failure and Dialysis Patients. 2006. McGraw-Hill’s Access Medicine.
-Pictures if used in this case are courtesy of Larry A. Scher, MD, Division of Vascular Surgery, North Shore University Hospital, Manhasset, New York.