The wound formed a pulsating mass

In patients with acquired arteriovenous fistula, the arterial and venous communication can be divided into direct and indirect. When the adjacent arteriovenous is injured at the same time, the wound margins directly meet each other, and they can communicate directly within a few days. This is called direct. Arteriovenous fistulas, such as arteriovenous wounds, cannot be directly conjoined, and there is a hematoma between the two. Later, the hematoma is mechanized to form a sac or tube that runs between the artery and the vein. The proximal arteries of the fistula are progressively dilated and elongated; the arterial wall is somewhat thickened in the early stage, degenerative changes occur in the later stage, smooth muscle fibers atrophy, elastic fibers decrease, the tube wall becomes thinner, and atheromatous plaque formation, such as a large fistula, adjacent The main artery of the fistula can expand to form an aneurysm, and the distal arteries shrink due to reduced blood flow. The veins gradually dilate, reaching the last valve at the distal end and the vena cava at the proximal end. If the fistula is large, the pressure in the veins increases sharply. After a few weeks of trauma, a pulsatile mass due to venous swelling can be seen locally.