The arteriovenous fistula consists of the union of an artery and a vein of the patient. These fistulas can -in pathological conditions- originate spontaneously in some circulatory diseases or be the consequence of various traumas, but this type of fistula is not referred to in this article, since these are pathological in nature.
The arteriovenous fistulas performed by Vascular Surgeons for patients with Chronic Renal Insufficiency , are "therapeutic" fistulas. They are exactly the union between an artery (in a deep situation) and a vein of the superficial venous system, usually in wrists, forearms or arms. Thus, the vein surgically attached to the artery develops gradually and increases its caliber over the course of several weeks, until it has a sufficient caliber (approximately 6 mm). of diameter) as to allow periodic dialysis.
Fistulas in upper extremities
The vast majority of dialysis fistulas are practiced 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 also present peripheral arterial pathology (in the lower extremities) over time and this discourages the creation of these fistulas in these extremities, since it could aggravate ischemia.
Alternatives to the creation of an arteriovenous fistula
The main alternative is the placement of a permanent dialysis catheter through a central vein, usually the internal jugular at the base of the neck, or the subclavian vein.. However, the main disadvantage of implanting central catheters is the potential risk of infection, taking into account that they go "internally" to the vicinity of the right atrium.. Therefore, whenever vascular access of the arteriovenous fistula type is available, it is preferable to the dialysis catheter, although there are numerous exceptions to this rule that, like so many aspects in Medicine, require extensive evaluation by the Nephrologist and the Vascular Surgeon. .
On other occasions the fistula can not be performed with veins from the patient 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 the arteriovenous fistula to avoid its obstruction
In fact, the specialist in Angiology and Vascular Surgery along with the specialist in Nephrology assess each case to offer the most appropriate to the patient whose vascular access does not work correctly. Sometimes the primary fistula does not mature properly or over time creates areas of stenosis ("narrowing" of the veins after repeated punctures). If it is detected, with endovascular surgery techniques these problems can be solved in many occasions, by means of prolonged dilation of these areas of stenosis with angioplasty balloons, as in the image.
Fistulography showing a stenosis due to hyperplasia in an arteriovenous fistula for dialysis, successfully treated with a percutaneous angioplasty.