All interventions are done as outpatient procedures. Apart from local infection, a contraindication to dilation of an area of stenosis is an AVF that is less than 6 weeks old due to the risk of disruption of the anastomosis. Once stenosis is diagnosed, dilation is performed by cannulation of the fistula itself. For stenoses located in the artery or at the anastomosis, a retrograde approach is used. If this retrograde approach is not feasible, an antegrade cannulation may be undertaken [10].

Catheterization of the arterial inflow is initially done with an angled glide wire and angled catheter. This is usually done with the sheath directed toward the arteriovenous anastomosis. After the catheter is placed in the arterial inflow and advanced to at least the mid-forearm or across the stenotic area if the narrowing is more proximal, the glide wire is exchanged for a stiffer guide wire.

Crossing and manipulating the wire across the anastomosis and centrally can be challenging at time, and various external manipulation and endovascular maneuvers may be needed. External manipulation is usually in the form of physically straightening out the angulations with pressure on the soft tissues. In terms of endovascular maneuvers, one can use microwires with shapeable tips. Rarely, a transbrachial or radial artery puncture is needed. An arterial puncture should be used as a last resort because the patient will be anticoagulated during the procedure [1, 17, 18]. Heparinization is required with ACT control to avoid iatrogenic thromboembolic phenomena.

Balloon size is dependent on the artery in question. In the event of a more central stenosis, the angioplasty balloon sizing is matched with the size of the artery, for example, if the subclavian artery needed treatment, the angioplasty balloon would be around 8 mm. In the case of treating the subclavian artery, a femoral approach usually provides better orientation. A long sheath or guide catheter is used to provide stability. Crossing usually is straightforward with a 0.035 glide wire (Fig. 29.3). On occasion when the narrowing is critical, then using a 0.014 or 0.018 wire can be useful to cross the lesion.

Balloon angioplasty of the inflow artery to a minimum of 4 mm is performed (occasionally to 3 mm in an immature AVF). There is a school of thought that the angioplasty for a juxta-anastomotic arterial lesion should be done with the angioplasty balloon directed centrally rather than peripherally so as to avoid steal phenomenon (Fig. 29.4). In the majority of the cases, a simple angioplasty suffices to treat the inflow stenosis (Fig. 29.5). Arterial lesions are more likely to respond than the traditional venous outflow stenosis in AVF which are resistant to balloon dilation and need high-pressure angioplasty balloons. In the event that there is non-resolution of the stenosis, a larger angioplasty balloon can be tried, but one has to be careful about the sizing. Too large angioplasty balloon can lead to dissection and rupture. Usually the angioplasty balloon size can be increased incrementally by about 1 mm.

In the event of nonresponse of a stenosis, a stent can be used if the flow is still compromised. In the upper extremity, preference will be given to self-expanding stents over balloon-mounted stents as they can resist deformation by external forces which is an important consideration in the arm and forearm (Fig. 29.6). In the case of central arterial lesions such as subclavian artery or near the arch, an angioplasty balloon-mounted stent can be used. The actual brand of stent used varies by institution.