Location of the shunt may be at the wrist, forearm or upper arm.
Requisites for the steal to develop:
(1) Low pressure runoff through the fistula.
(2) Atherosclerostic narrowing of distal arteries (causing high resistance).
Clinical features:
(1) The onset may be insidious over weeks.
(2) The patient may notice numbness or paresthesias in the fingers.
(3) Fingers may become stiff and swollen.
(4) As the condition progresses the patient may develop signs of digital ischemia, with pallor, loss of sensation, trophic ulcers and dry gangrene of the fingers.
(5) The radial pulse is very weak to absent.
In severe cases acute arterial insufficiency may occur at the time of shunt surgery.
A characteristic feature is relief of symptoms and return of the radial pulse upon occluding the venous limb of the shunt. Digital pulse oximetry will show a low oxygen saturation before with correction after venous limb occlusion.
Doppler ultrasonography can be used to demonstate the altered flow.
