Timing of Procedure

An emergency fistulogram should be performed for refractory access-site bleeding after hemodialysis. Emergency angiography and intervention are also indicated for failing or thrombosed hemodialysis accesses in patients with hyperkalemia, volume overload, or refractory hypertension.

Urgent catheter-based treatment is indicated for patients with thrombosed hemodialysis accesses. Delays in treatment more than 24 hours after diagnosis or more than 48 hours after hemodialysis may require temporary catheter placement or increase the risks of complications. Urgent angiography should also be performed for malfunctioning but nonthrombosed dialysis accesses because thrombosis may be imminent.

Contraindications to percutaneous treatment include graft infection, a central right-to-left shunt, or pulmonary hypertension. A relative contraindication to catheter-based therapy is thrombosis of new fistula or graft within 30 days of surgical creation or revision. In this situation, thrombosis has likely arisen from a technical problem or anatomy not amenable to catheter-based therapy.

Hemodialysis Access Anatomy

An autogenous arteriovenous access is surgically created by directly anastomosing a native outflow vein (Fig. 21-1) to a native inflow artery (Fig. 21-2), usually in the form of an end-to-side anastomosis. A prosthetic arteriovenous access is constructed by surgically interposing a segment of polytetrafluoroethylene (PTFE) between a native artery and a native vein in either a straight or looped configuration. Common patterns include the brachial-cephalic configuration in the forearm or the brachial-basilic configuration in the upper arm (Fig. 21-3). For the purposes of this chapter, an autogenous arteriovenous access will be referred to as a fistula, a prosthetic arteriovenous access as a graft, and when mentioned together, both types will be referred to as accesses.

Figure 21-1 Venous anatomy of the upper extremity. Rt, right; SVC, superior vena cava; v, vein.

(Reprinted from Bittl JA. Catheter interventions for hemodialysis fistulas and grafts. JACC Cardiovasc Interv 2010;3:1–11, with permission from Elsevier.)

Figure 21-2 Pertinent arterial anatomy of the upper extremity. a, artery; Rt., right.

(Reprinted from Bittl JA. Catheter interventions for hemodialysis fistulas and grafts. JACC Cardiovasc Interv 2010;3:1–11, with permission from Elsevier.)

Figure 21-3 Access anatomy of the upper extremity. A radial-cephalic fistula is created by an end-to-side anastomosis between the cephalic vein and the radial artery, with ligation of the distal stump of the cephalic vein. A brachial-cephalic graft in the forearm (lower arm arrows) requires the surgical interposition of a polytetrafluoroethylene (PTFE) loop using end-to-side connections. A brachial-basilic graft in the upper arm (upper arm arrows) requires the surgical insertion of a PTFE loop using end-to-side connections.

(Reprinted from Bittl JA. Catheter interventions for hemodialysis fistulas and grafts. JACC Cardiovasc Interv 2010;3:1–11, with permission from Elsevier.)

The selection of a particular permanent hemodialysis access creation is based on the principle of “Fistula First,” which is derived from evidence favoring the creation of an autogenous fistula whenever possible before resorting to a PTFE graft. The selection of a specific location is based on the recommended sequence of using the nondominant arm before the dominant arm, the forearm before the upper arm, and the upper extremity before the lower extremity.

Mechanisms of Hemodialysis Access Failure

Although the primary patency of fistulas is low, autogenous fistulas have better long-term patency than prosthetic grafts. After surgical creation, <50% of fistulas mature adequately to support hemodialysis. When fistulas mature adequately, they remain patent for a median of 3 to 7 years. The primary patency of PTFE grafts exceeds 80%, but prosthetic accesses remain patent for only 12 to 18 months.

Two failure modes of fistulas and grafts are amenable to interventional treatment (Fig. 21-4). An inflow stenosis in newly placed fistulas may inhibit physiologic hypertrophy and maturation. An outflow stenosis in chronically used fistulas and grafts may cause high pressures and thrombosis. Although 50% of malfunctioning accesses ultimately undergo thrombosis, this is not the primary cause of failure. Instead, shear stress and fibromuscular hyperplasia of the outflow vein causes a progressively worsening stenosis, which then leads to stasis and eventual thrombosis (see Fig. 21-4).

Figure 21-4 Pathogenesis of dialysis access failure. The early appearance of an inflow (anastomotic) stenosis may lead to failure of fistula maturation. The late development of a stenosis in the outflow segment of a fistula or graft is the cause of stasis and access thrombosis.

(Reprinted from Bittl JA. Catheter interventions for hemodialysis fistulas and grafts. JACC Cardiovasc Interv 2010;3:1–11, with permission from Elsevier.)

Stenoses can occur anywhere in a dialysis access, but the most common location is the anastomosis between the prosthetic graft and the outflow vein. Although fistulas contain no outflow anastomosis, they are also susceptible to stenosis formation in the outflow vein.

Hemodialysis Access Monitoring, Surveillance, and Testing

Monitoring refers to regular physical examination and the assessment of dialysis adequacy. A well-functioning fistula or graft should have a prominent thrill, loud medium-pitched bruit, and minimal pulsation. A soft bruit suggests the presence of an inflow stenosis, whereas a prominent pulsation, short but high-pitched bruit, or aneurysmal dilatation suggests the presence of an outflow stenosis. Marked arm edema suggests the presence of dual venous obstruction (cephalic and basilic) or a subclavian vein stenosis or occlusion.