Arteriovenous Anastomosis: A vessel that directly interconnects an artery and a vein, and that acts as a shunt to bypass the capillary bed. Not to be confused with surgical anastomosis, nor with arteriovenous fistula.Ergotamine: A vasoconstrictor found in ergot of Central Europe. It is a serotonin agonist that has been used as an oxytocic agent and in the treatment of MIGRAINE DISORDERS.Sumatriptan: A serotonin agonist that acts selectively at 5HT1 receptors. It is used in the treatment of MIGRAINE DISORDERS.Anastomosis, Surgical: Surgical union or shunt between ducts, tubes or vessels. It may be end-to-end, end-to-side, side-to-end, or side-to-side.Arteriovenous Shunt, Surgical: Surgical shunt allowing direct passage of blood from an artery to a vein. (From Dorland, 28th ed)Regional Blood Flow: The flow of BLOOD through or around an organ or region of the body.Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).