Findings/Discussion AV fistula with outflow stenosis far from anastomosis Stenosis typically due to fibrotic, hyperplastic or elastic lesions. –Increased flow/pressure in the vein from arterial shunting is believed to contribute to lesion formation. –The most common acute complications are thrombosis or inadequate flow rates. Also accounts for 85% of complications during the life of dialysis access. –Remainder of complications due to infection, pseudoaneurysm formation and steal syndrome.

AV fistula cont.. Inability to aspirate blood at a satisfactory rate indicates an inflow problem like stenosis at the arterial anastomosis. When excessive pressure is required to return blood through the venous needle or clearance of metabolites is slow, a venous outflow lesion is suggested. Fistulas have superior longevity compared with grafts but require several months to enlarge sufficiently to accommodate needles and flow rates. 30% fail to mature or thrombose acutely.

Basic technique Allows for diagnosis and intervention Access – based on physical exam Approach – short 18-gauge peripheral IV catheter over an inch guidewire –Non-ionic contrast injected by hand Therapeautic – exchange 18 gauge catheter for 5 or 6 french sheath over a guidewire. Heparinize with units. Outflow lesions may be dilated with high pressure balloons (15-20 atm) if fibrotic.

Therapeutic results Satisfactory dialysis achieved in 90-95% of patients after intervention. –Patency at 6 months 65%; 12 months 30% Angioplasty complications: Thrombosis, dissection and rupture. –Thrombosis responds to pharm/mech thrombectomy –Dissection managed with prolonged balloon inflation to tack down the flap or stent placement –Rupture tx with manual compression or prolonged balloon inflation across the rupture. The vein remains patent, while extravasation ceases.