The arteriovenous fistula consists of the union of an artery and a vein of the patient himself. These fistulas can – under pathological conditions – originate spontaneously in some circulatory diseases or as a consequence of various traumas, but we do not refer to this type of fistula in this article, as these are of a pathological nature.
The arteriovenous fistulas that we Vascular Surgeons perform for patients with CKD are “therapeutic” fistulas. They are exactly the union between an artery (in deep situation) with a vein of the superficial venous system, usually in wrists, forearms or arms. Thus, the vein surgically joined to the artery gradually develops and increases its caliber over the course of several weeks, until it has a sufficient caliber (approximately 6 mm). diameter) to allow periodic dialysis.
Upper extremity fistulas
The vast majority of dialysis fistulas are performed in the upper limbs, since they are much more accessible than the veins of the lower extremities and generally have a lower rate of any type of complication. In addition, patients with severe renal insufficiency may eventually present with peripheral arterial pathology (in the lower extremities) and this discourages the creation of these fistulas in these extremities, as it could aggravate the ischemia.
Alternatives to the creation of an arteriovenous fistula
The main alternative is the placement of an indwelling dialysis catheter through a central vein, usually the internal jugular vein at the base of the neck, or the subclavian vein. However, the main disadvantage of the implantation of central catheters is the potential risk of infection, taking into account that they go “internally” to the vicinity of the right atrium. Therefore, whenever an arteriovenous fistula type vascular access is available, it is preferable to the dialysis catheter, although there are numerous exceptions to this rule which, like so many aspects in Medicine, require extensive evaluation by the Nephrologist and the Vascular Surgeon.
On other occasions the fistula cannot be performed with the patient’s own veins because they are of insufficient quality, and the main surgical alternative in this case is a bypass with prosthesis, thus directly joining the venous system with the artery.
Treatment of arteriovenous fistula to prevent its obstruction
Indeed, the specialist in Angiology and Vascular Surgery together with the specialist in Nephrology evaluate each case in order to offer the most appropriate solution to the patient whose vascular access does not function correctly. Sometimes the fistula does not mature correctly in the primary form or with the passage of time creates areas of stenosis (“narrowing” of the veins after repeated punctures). If detected, endovascular surgery techniques can often solve these problems by prolonged dilatation of these areas of stenosis with angioplasty balloons, as in the image.
Fistulography showing stenosis due to hyperplasia in an arteriovenous fistula for dialysis, successfully treated with percutaneous angioplasty.