Problems and Complications of Arteriovenous Fistula

• Insufficiency of dilated veins. This complication is usually developed in a shunt which is produced in the wrist and its origin is unknown.

• Haemorrhage. This may take place immediately after the creation of the shunt and, in this case, we have to open it and ligate the vessel that is responsible. Later if there is a haemorrhage it is usually due to infection.

• Thrombosis. Thrombosis is divided into early and late. Thrombosis at the early stage of the procedure is unusual and takes place at a rate of 5%. In these cases the problem is due to coagulation or hypotension. Small veins are not a contraindication for a successive shunt when the procedure is performed by an experienced surgeon. If the thrombosis takes place during the first 24-48 h then the A-V shunt must be explored in order to remove the clot with a Fogarty catheter. Thrombosis of the A-V shunt after long-lasting function is unusual but, if this is the case, we have to open the shunt as soon as possible and remove the clot with a Fogarty catheter. Then the creation of a new shunt above the old one is preferable.

• Aneurysm formation. It is possible that at the point of the shunt or at the points of puncture there may be formation of an aneurysmal dilatation of the arterial-ized vein and creation of a clot attached to the wall of

Cephalic vein

Cephalic vein

Fistula Problems

Fig. 13.1.1a-e a The site of the A-V shunt. b-e Preparation of the radial artery and the cephalic vein. Creation of the A-V fistula

Fistula Problems Pic

the vessel, which may become detached and constrict a proximal normal vein. It is possible that the puncture at the point of the aneurysm may create problems or difficulties in haemostasis. A pseudo-aneurysm could possibly develop through the creation of a haematoma at the place of puncture of the arterialized vein. Infection. A primary infection at the A-V fistula is very rare (1%) in contrast to the external A-V shunt, which is usually where the infection takes place. The

Fig. 13.1.1a-e a The site of the A-V shunt. b-e Preparation of the radial artery and the cephalic vein. Creation of the A-V fistula administration of antibiotics and avoiding puncture at the point of the infection will lead to its improvement.

Ischaemia of the hand and steal syndrome. Mass diversion of arterial blood into the vein of the anastomosis may cause ischaemia of the arm when the collateral circulation is inadequate. Clinical manifestation of the syndrome is characterized by a painful and cold arm especially in the area which receives its blood supply from the radial artery (thumb, index and middle finger) and may lead to ischaemia, ulcer or gangrene if it is not dealt with quickly. Ischaemia is more common in A-V shunts of the elbow rather than the wrist. Cardiac failure. An increase of cardiac preload up to 10% could possibly take place after the creation of an A-V shunt but rarely produces any problems. The flow between the shunt has been calculated to vary from 300 to 500 cm3/min, rarely up to 1000 cm3/min. In

Fig. 13.1.2 End-to-side arteriovenous shunt

these cases the increased cardiac preload will become a problem for patients with cardiac failure. • Venous hypertension. It is possible to note an increase of pressure in the peripheral veins when a large part of arterial flow reaches them and as a result we have oedema and cyanosis of the arm. When this disorder is observed in the shunt between the radial artery and the cephalic vein of the wrist, all of the symptoms concern the thumb; this becomes extremely painful, with vein dilatation, ulcers, eczema and serous fluid secretion from the arterial bed of the nails. These manifestations form the syndrome called painful thumb. Oedema of the tissues of the wrist may cause wrist tunnel syndrome. In order to diagnose painful thumb syndrome, it must be examined clinically and possibly by angiography of the shunt.

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