What Is an Arteriovenous Fistula?

There are abnormal channels between arteries and veins called arteriovenous fistulas. Because the normal blood flow from the artery flows into the accompanying vein, it can cause local vascular lesions of the fistula and hemodynamic changes in the local, peripheral circulation and systemic system of the fistula. Can be congenital or acquired due to trauma.

Basic Information

English name: arteriovenous fistula
Visiting department: surgical
Common causes: Congenital: abnormal channels remaining between arteries and veins during development and evolution; acquired: trauma

Common symptoms: Local hematoma, swelling of the affected limb, numbness, pain, fatigue, pulsating mass with local buzzing, chest failure, heart palpitations, shortness of breath, etc.

Causes of arteriovenous fistula

Congenital arteriovenous fistula

It is caused by the residual abnormal channels between arteries and veins during the development and evolution of the embryo's mesoderm.

2. Acquired arteriovenous fistula

It is mainly caused by trauma, including penetrating injury, crush injury, etc. (such as various puncture injuries, gun injuries, flying injuries of steel and glass fragments, etc.). Hematomas were formed in the injured area, and the capsule wall of arteriovenous fistula was formed after the hematoma was mechanized.

Clinical manifestations of arteriovenous fistula

Acute acquired arteriovenous fistula can appear immediately after injury, or after the clot dissolves outside the arteriovenous communication, there is a hematoma in the area of the injury, and most of them have tremor and murmur.

Patients with chronic arteriovenous fistula have swelling, numbness, pain, and fatigue. There is a local buzzing in the pulsatile mass. Heart failure may have chest tightness, palpitations, and shortness of breath. Common signs are:

1. Noise and tremor in the fistula area

Regardless of the size of the arteriovenous fistula, a typical, rough and continuous rumbling sound can be heard at the site of the arteriovenous fistula, called a "machine-like" murmur. The murmur increases during systole and is conducted along the proximal and distal sides of the main vessel. This murmur is distinguished from a weak diastolic murmur caused by a pseudoaneurysm and a systolic murmur caused by arterial stenosis.

2.Fast pulse rate

This is the result of increased Bainbridge reflexes due to increased venous venous blood volume or increased cardiac workload due to a decrease in mean arterial pressure.

3. Heart enlargement and heart failure

Because a large amount of blood quickly flows into the vein through the fistula, the venous pressure increases, and the amount of returning blood in the heart increases, causing the heart to enlarge. Progressive enlargement of the heart can lead to heart failure. The extent of heart enlargement and heart failure is closely related to the size, location and age of the fistula. Fistulas near the heart, such as the direct branch of the aortic arch (carotid artery, innominate artery, subclavian artery) and arteriovenous fistula associated with vein formation, have early and severe heart failure.

4. Local heating

The skin temperature of the affected limb increases at the surface of the arteriovenous fistula, with high flow rates. The skin temperature of the arteriovenous fistula may be normal or lower than normal.

5. Venous Insufficiency

Direct communication between arteries and veins increases venous pressure. In most patients, superficial varicose veins near or distal to the arteriovenous fistula. Skin pigmentation, ulcers often occur on the toes or fingers, showing symptoms similar to deep vein thrombosis.

6. Distal limb ischemia

It is more common in arteriovenous fistulas with high flow shunts, and reduced blood flow in the distal limbs leads to ischemic signs.

Arteriovenous fistula

Color Doppler ultrasound

For superficial arteriovenous fistulas, ultrasound can very accurately find the arteriovenous fistula site, the size of the fistula, and the flow rate, which is very helpful for qualitative diagnosis.

2. Arteriography

You can determine the location and size of the fistula, as well as the surrounding blood vessels and collateral circulation. However, angiography is invasive and not the first choice.

3.CTA or MRA

CT arteriography can determine the location and scope of arteriovenous fistula, but the fistula is not easy to determine. Magnetic resonance angiography is similar to CT angiography, but does not require contrast agents and is not radioactive.

4. Measurement of cardiac output

Echocardiography and indicator dilution method can measure cardiac output and understand heart function.

5. Other inspections

Including the determination of venous blood oxygen and venous pressure.

Arteriovenous fistula diagnosis

The diagnosis of arteriovenous fistula is generally not difficult. In congenital arteriovenous fistula, swelling and color change of limbs can be found in young children. Acquired arteriovenous fistula mostly occurs after trauma, and the patient may have a pulsating mass with a local buzzing sound. Swelling on one side, varicose veins and venous valve insufficiency, local skin temperature of the limb is higher than on the opposite side, and scars, murmurs, and tremors in the injured area should be considered for diagnosis of arteriovenous fistula.

Arteriovenous fistula treatment

In recent years, due to the rapid progress of vascular surgery, the level of vascular suture and transplantation has been continuously improved. Once the diagnosis of acquired arteriovenous fistula is confirmed, early surgery is advocated.

1. Acute arteriovenous fistula surgery

Patients generally permit early surgery. The wound was thoroughly debrided, and the injured arteries and veins were freed from the proximal and distal ends and controlled with plastic bands. Arteries can be repaired by fistula repair or fistula anastomosis or autologous saphenous vein transplantation. Veins also need to be repaired to rebuild blood flow, which can reduce limb edema.

2. Surgical treatment of chronic arteriovenous fistula

(1) Arteriovenous fistula ligation and closure is an ancient surgical method. The use of closed surgery on non-stem vessels is a safe and effective method. However, closed surgery on the main blood vessels can produce distal limbs, especially lower limb blood supply and chronic nutritional disorders, with intermittent claudication, ischemic pain, numbness, cold, edema, ulcers, and muscle atrophy. use. The surgical methods include proximal arterial ligation of the fistula, quadrulateral ligation, and occlusive intratumor suture.

(2) Arteriovenous fistula resection In recent years, for acquired arteriovenous fistulas, fistectomy and arteriovenous reconstruction have been mainly performed: repair of fistula through vein incision; repair of fistula, suture repair of artery and vein fistula resection and arterial opposite end anastomosis; fistula resection and vascular transplantation: if the range of arterial defect is longer, autogenous vein + vascular graft can be used.

(3) Fistula-free arterial vascular graft surgery. Some lesions are located in anatomical parts that are not easily exposed, or are closely adhered to adjacent blood vessels and nerves. Vascular transplantation is performed near and distal from the diseased artery to maintain blood supply to the distal limb.

(4) Intra-arterial embolization Interventional inferior arterial puncture angiography, intubation to arteriovenous fistula site, embolization of the fistula seen. If the arteriovenous fistula of the main artery can still be covered with a stent graft. This method is a minimally invasive treatment with less pain and less trauma.