An arterial fistula is an abnormal connection between an artery and a vein. This condition can occur naturally or be created surgically, often for medical purposes such as dialysis. The direct link allows blood to flow from the artery into the vein, bypassing the capillaries. These fistulas can lead to various complications, including changes in blood flow and pressure. While some people may not experience symptoms, others might notice swelling or discomfort in the affected area. Monitoring and management are essential to prevent potential issues related to the altered blood circulation.