Inflammation and Restenosis
Treatment for Stenotic Failure of Dialysis Access Sites
Mercator is investigating the use of the Micro-Infusion Catheter to prevent neointimal hyperplasia associated with stenotic dialysis access failure.The company’s treatment for this condition will be adjunctive to procedures such as blood clot removal and angioplasty to extend the life of the dialysis access site. By stabilizing the failed access site after intervention, this treatment is anticipated to substantially increase the life of the access site after the first intervention — postponing the need for secondary interventions.
Dialysis Access Failure
An estimated 350,000 U.S. patients are on hemodialysis to remove wastes and extra fluids from the blood to treat advanced and permanent kidney failure. In order to provide an access site to facilitate the withdrawal, filtering, and re-infusion of blood, most patients have either a tubular graft implanted in their arm or a surgical fistula placed between an artery and vein. Extending the life of hemodialysis access with minimal surgical intervention is critical for managing both patient outcome and cost.
Access failure is often the result of venous neointimal hyperplasia, an inflammatory process similar to scar formation in response to injury. While some inflammation will always occur at an access site due to the high flow rates needed for treatment, it is critical to limit any vascular injury associated with re-intervention to keep the site open. Angioplasty injury leads to shorter periods between access surgeries and can severely compromise patient health.
Soon after a graft or fistula procedure is completed, inflammatory buildup of fibrous tissue leads to occlusion of the blood vessel connections at the graft or at the artery and vein (the arteriovenous anastomosis). This eventually chokes off blood flow and leads to a blood clot clogging the access site for dialysis. The initial effective open life of grafts (primary patency) is typically short: 50% of patients have an occlusion in the first year; 75% of patients have an occlusion before the end of the second year. Treatment of primary site failure includes blood clot removal and balloon angioplasty to compress the impinging tissue and reopen the path to restore blood flow.
The patency of grafts and fistulae after angioplasty is worse than the primary patency, with half of the grafts failing in the first three months and half of the fistulae failing in the first six months. An estimated 250,000 of these angioplasty procedures will be performed in 2005. Extending the patency of grafts and fistulae after blood clot removal and angioplasty can significantly reduce the morbidity and healthcare costs experienced by end stage renal disease patients.