Arteriovenous

Arteriovenous, often abbreviated as AV, is an anatomical and physiological term describing the relationship between arteries and veins. In the circulatory system, arteries transport oxygen-rich blood from the heart to tissues, while veins return it to the heart. Normally, these vessels are connected by a network of capillaries that slow and regulate flow. An arteriovenous connection, or AV shunt, bypasses the capillary bed and allows blood to pass directly from arteries into veins. AV connections can be congenital (present at birth) or acquired through injury, surgery, or disease. They are described by their structure (fistula, malformation) and their location.

An arteriovenous fistula is a direct connection between an artery and a vein. Fistulas may be congenital or formed surgically for medical reasons, such as providing access for hemodialysis. They typically have high-flow, high-pressure characteristics and can cause symptoms such as a palpable thrill or audible bruit at the connection, limb swelling, or heart strain if the flow is extensive. Some fistulas are monitored and preserved, while others are treated to repair or redirect flow.

An arteriovenous malformation (AVM) is an abnormal tangle of arteries and veins in which blood flows directly between arterial and venous channels without an intervening capillary bed. AVMs are most commonly discussed in the brain or spine, where they can present with seizures, headaches, or hemorrhage. They can also occur in other organs. Diagnosis relies on imaging such as magnetic resonance imaging, computed tomography, or catheter-based angiography. Treatment is individualized and may include endovascular embolization, surgical resection, radiosurgery, or observation for small, asymptomatic lesions.

The term arteriovenous also appears in reference to normal physiologic shunts and to pathological conditions affecting circulation and tissue perfusion.