Interventions for Failing Hemodialysis Access

21 Interventions for Failing Hemodialysis Access



During the past decade, the management of failing hemodialysis accesses has shifted from surgical repair to catheter-based approaches. The advantages of endovascular approaches over surgery include the avoidance of temporary hemodialysis catheters, the preservation of venous segments for future access creation, and the prolongation of total survival time on hemodialysis. This chapter reviews the mechanisms of dialysis access failure and describes the interventional management of failing and thrombosed fistulas and grafts.




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.





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).



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.


Jun 5, 2016 | Posted by in CARDIAC SURGERY | Comments Off on Interventions for Failing Hemodialysis Access

Full access? Get Clinical Tree

Get Clinical Tree app for offline access