Declotting and revision of an arteriovenous fistula

Over years of dialysis, an arteriovenous fistula can develop problems. The most common is a narrowing (stenosis) of the vein, which hampers dialysis and can lead to thrombosis: the fistula blocks, the thrill disappears and dialysis is no longer possible. Other problems can occur: marked widening (aneurysm), excessive flow that tires the heart, or a cold hand because blood is diverted. Treatment depends on the problem. A blocked fistula is cleared by removing the clot, through a small incision with a balloon catheter, or by an endovascular route. The underlying narrowing is corrected by balloon angioplasty under X-ray guidance, by a new connection slightly higher up, or by a short bypass. An aneurysm can be reduced or replaced, and excessive flow reduced by a calibrated narrowing. If the fistula has thrombosed, action is needed quickly, ideally within 24 to 48 hours, to give the best chance of saving it and avoiding a catheter. Any change (weaker thrill, prolonged bleeding after a session, swollen arm, abnormal pressures during dialysis) should be reported. At Clinique Pasteur Tunis, these procedures are performed in the operating theatre or the catheterisation laboratory, with an organisation that allows rapid care so as not to interrupt the dialysis schedule.