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September 3, 2011
The arteriovenous fistula is the inborn or resulted from an injury anastomosis between a vein and an artery on which the arterial blood comes to venous system. Normal the blood stream moves from heart on arteries to a capillary bed, and then through veins — back to heart. In other words at an arteriovenous fistula direct connection of a vein with an artery is observed. Fistulas happen inborn and acquired.
Inborn arterial fistulas can be located in any part of a body. The acquired fistulas can be caused by damages of vessels at operation, an injury or because of an aortic aneurysm erosion with the advent of communication of her cavity with a vein cavity. Similar fistulas can artificially be created.
The acquired fistulas appear at an injury, for example, at knife wound, operation as a result of which an adjacent vein and an artery are injured. Most often the fistula forms right after an injury, and in the field of education of a fistula hypostasis because of blood hit in soft tissues is observed at once, passing a capillary bed.
Happens so that the arteriovenous fistula is created intentionally, for example, during treatment by a hemodialysis to avoid a repeated puncture of vessels. Usually in this case the fistula forms in a forearm. Arteriovenous fistulas which increase in sizes over time lead to deterioration in blood supply in the territory located below a fistula and owing to increase in emission by blood heart, to a heart overload.
Symptoms of an arteriovenous fistula
Symptoms of arteriovenous fistulas depend on blood volumes which come to venous system, and also from an arrangement of the fistula. At inborn arteriovenous fistulas fabrics, adjacent to it, swell and get a red shade. Especially not attractively it looks in case of finding of a fistula on a face.
Small fistulas usually appear without any symptoms. At large volume of the blood coming to veins lowering of arterial pressure, increase in pulse pressure, increase in heart rate can be observed (tachycardia) that leads to a heart overload. In this case urgent treatment of an arteriovenous fistula by operational methods is necessary.
In the field of a fistula hypostasis, a phlebectasia and their pulsation, temperature increase of skin is, as a rule, observed, and here below a fistula temperature is reduced. In the departments of an extremity located below a fistula trophic disturbances can be observed.
Complications of an arteriovenous fistula not seldom lead to the fact that it becomes the center of a bacterial infection, and large fistulas lead to development of a varicosity of legs, and also heart failure.
Diagnosis of an arteriovenous fistula
The diagnosis is made by the doctor on the basis of survey of the patient and results of laboratory researches. At not a deep arrangement of a fistula, it can be palpated as volume education, with the pulsing veins. On the expected location of an arteriovenous fistula the doctor listens to noise by means of a stethoscope.
Carrying out ultrasonic duplex scanning helps to confirm the diagnosis (doppler sonography), and in case of a deep bedding of a fistula the angiography is carried out. Also the computer tomographic and magnetic and resonant angiography, less invasive methods, however and less informative is carried out.
Diagnosis of an arteriovenous fistula by method of an angiography represents visualization of vessels at introduction of contrast as a result of x-ray emission, and allows to reveal exact localization of a fistula, and also its size.
Treatment of an arteriovenous fistula
Inborn fistulas of the small sizes can be removed by means of a method of laser coagulation. This operation is performed by the vascular surgeon. Similar operations are especially dangerous if the arteriovenous fistula is located near a brain, eyes or other important bodies.
The acquired arteriovenous fistulas are treated in the emergency order. For surgical intervention the angiography is carried out, and then the decision on treatment methods is made. The arteriovenous fistula can be removed in the endovascular way when under the influence of X-ray a certain substance which blocks through service between a vein and an artery is entered into a vessel. In more difficult cases operation is performed.
Treatment of the complications which arose at an arteriovenous fistula is carried out by the general rules.
Complications of an arteriovenous fistula
Most often complications complicate symptoms of an arteriovenous fistula being shown by the increased cosmetic defects – in the form of reddish, sometimes crimson, integuments around a fistula that looks very not esthetically. If an arterial fistula not to treat, then it can lead to emergence and development of aneurism, varicosity, as well as thrombosis.
The arteriovenous fistula is followed by what large volumes of blood from an artery under strong pressure gets into veins. However vein walls weaker, than at an artery, and a blood flow the vein extends that leads to damage of its walls. Because in an artery pressure falls, and increases in a vein, blood supply of certain sites where the struck vessels are located, decreases.
One more complication of arteriovenous fistulas is development in patients of heart failure, owing to lowering of arterial pressure, and increase in cordial reductions.
Section: Diseases of vessels