Findings/Discussion

3. 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.

4. 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.

5. Basic technique • Allows for diagnosis and intervention • Access – based on physical exam • Approach – short 18-gauge peripheral IV catheter over an 0.035-inch guidewire • Non-ionic contrast injected by hand • Therapeautic – exchange 18 gauge catheter for 5 or 6 french sheath over a 0.035 guidewire. • Heparinize with 3000-5000 units. • Outflow lesions may be dilated with high pressure balloons (15-20 atm) if fibrotic.

6. 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.