The areas affected obviously differ somewhat according to whether an AVG or AVF is present. All of these lesions, however, are similar in the sense that they are only surrounded by soft tissue, making endovascular intervention attractive. Lesion location in failing AVGs can be classified into four categories: the arterial anastomosis, within the graft, the venous anastomosis, and the venous outflow tract (from the arteriovenous anastomosis to the cephalic arch). In AVFs, there are only the arterial anastomosis, body of the vein (loosely defined as the accessible segment), and outflow tract to the CCJ.

Surgical techniques were originally used to manage venous anastomotic stenosis, including placement of an interposition graft or enlargement of the anastomosis by means of patch angioplasty. Both techniques have been shown to be equivalent in terms of outcomes [11]. The main disadvantage of using an interposition graft is the increased risk of infection (and perhaps decreased patency) due to substitution of autogenous vein with a prosthetic graft [12], although obviously autologous vein can in theory solve this problem. A patch angioplasty simply enlarges the area of stenosis without addressing the fundamental issue (i.e., neointimal hyperplasia), increasing the risk of restenosis, although this may then occur at a different and less critical location within the anastomosis.

Fully occluded outflow veins in this region require individualized treatment. Endovascular options are usually limited due to the chronicity of these lesions and the inability to cross them with a wire. In this situation, open surgical repair is usually required, with the goal being to establish adequate venous outflow. The open surgical approach depends on the extent and location of the occlusion and the status of the superficial and central veins. The most commonly used options include extensive mobilization and reimplantation of the distal segment of the AVF to a vein with patent outflow (e.g., distal cephalic vein-axillary vein), basilic or brachial vein translocation (e.g., distal cephalic vein-basilic vein), or the use of an interposition graft (autogenous or prosthetic) to bypass the lesion [9]. The patent outflow vein (i.e., cephalic) does not always need to be brought down to reach the deep system; the deep vein itself can be transected without significant clinical sequelae and brought up to meet the cephalic vein “halfway,” thus preserving length for cannulation.

Most stenoses involving this anatomic segment respond well to endovascular techniques. In order of intervention, balloon angioplasty, cutting balloons for resistant lesions, or bare metal stents can all be used. Any percutaneous intervention should begin with imaging of the complete circuit to include the entire conduit from the arterial anastomosis to the central venous outflow. Endovascular percutaneous transluminal angioplasty (PTA) is the most common endovascular intervention for stenosis in this region. It is important to consider the pathophysiologic importance of neointimal hyperplasia as a cause of failure in this anatomic segment. The time and pressure required to treat the areas of stenosis can be increased due to neointimal hyperplasia. The result of these higher pressures is uncontrolled trauma to the vein, which can restimulate the neointimal hyperplasia process, leading to recurrent stenosis. Based on that assumption, multiple studies suggest that the best option may be initial use of a cutting balloon followed by PTA performed at a lower pressure [13–16]. Another important factor is the increased risk of extravasation following PTA as a result of tearing of the fibrotic neointimal hyperplasia, as opposed to the tendency to dissect in the setting of an atherosclerotic plaque.

Even though PTA has replaced surgical revision for hemodialysis access-related venous stenoses and occlusions [18], primary patency rates remain poor as a result of restenosis due to neointimal hyperplasia [17]. Even after placement of a bare metal stent, neointimal hyperplasia is still the major reason for restenosis [18]. However, when compared to angioplasty alone, stenting exhibits similar or improved patency rates. Stents are also useful for salvaging failed angioplasty procedures and thereby maintaining patency of the hemodialysis graft. Some studies have suggested that primary patency following stenting was significantly better than the primary patency of the entire vascular access [19].

The type of stent used has been a subject of study. Covered stents have been used to prevent recurrent stenosis, probably by preventing the ingrowth of hyperplastic tissue, and thus, avoid the early failures seen with bare metal stents. This is particularly true for treating stenoses at the venous anastomosis of prosthetic AV accesses, where covered stents have been shown to have a patency advantage over bare metal stents [20].

The terminal portion of the cephalic vein, where it dives perpendicularly in the deltopectoral groove to join the axillary or subclavian vein, is labeled the cephalic arch. For unknown reasons, this is a segment particularly prone to stenosis. It is usually treated with conventional angioplasty, although high rates of restenosis are seen, and thus in and of itself is an area of research interest [17, 20]. The cephalic arch represents the outflow for any cephalic-based access (although radiocephalic AVFs usually include the deep system as outflow). Most recent studies have shown that management with bare metal stents results in unsatisfactory patency rates due to the rapid development of in-stent stenosis [21]. Some recent data support the use of covered stent grafts as an alternative to bare metal stents in recurrent cephalic arch stenosis after conventional PTA [20]. It should be strongly emphasized that any stent, whether covered or not, should protrude only minimally (or not at all) into the deep system, as this increases the risk of thrombosis of the deep as well as cephalic veins, which can lead to significant superior vena cava syndrome.