The fistula may cause symptoms and signs of Arterial insufficiency (eg, ulceration due to reduced arterial flow or ischemia) Chronic venous insufficiency due to high-pressure arterial flow in the affected veins (eg, peripheral edema, varicose veins, stasis pigmentation) Emboli may pass from the venous to the arterial circulation (and cause ulceration when they lodge in distal vessels), although pressure differences make this unlikely.