Saphenous Vein: The vein which drains the foot and leg.Veins: The vessels carrying blood away from the capillary beds.Varicose Veins: Enlarged and tortuous VEINS.Femoral Vein: The vein accompanying the femoral artery in the same sheath; it is a continuation of the popliteal vein and becomes the external iliac vein.Venous Insufficiency: Impaired venous blood flow or venous return (venous stasis), usually caused by inadequate venous valves. Venous insufficiency often occurs in the legs, and is associated with EDEMA and sometimes with VENOUS STASIS ULCERS at the ankle.Graft Occlusion, Vascular: Obstruction of flow in biological or prosthetic vascular grafts.Portal Vein: A short thick vein formed by union of the superior mesenteric vein and the splenic vein.Popliteal Vein: The vein formed by the union of the anterior and posterior tibial veins; it courses through the popliteal space and becomes the femoral vein.Mammary Arteries: Arteries originating from the subclavian or axillary arteries and distributing to the anterior thoracic wall, mediastinal structures, diaphragm, pectoral muscles and mammary gland.Jugular Veins: Veins in the neck which drain the brain, face, and neck into the brachiocephalic or subclavian veins.Tissue and Organ Harvesting: The procedure of removing TISSUES, organs, or specimens from DONORS for reuse, such as TRANSPLANTATION.Coronary Artery Bypass: Surgical therapy of ischemic coronary artery disease achieved by grafting a section of saphenous vein, internal mammary artery, or other substitute between the aorta and the obstructed coronary artery distal to the obstructive lesion.Vascular Patency: The degree to which BLOOD VESSELS are not blocked or obstructed.Pulmonary Veins: The veins that return the oxygenated blood from the lungs to the left atrium of the heart.Ultrasonography, Doppler, Duplex: Ultrasonography applying the Doppler effect combined with real-time imaging. The real-time image is created by rapid movement of the ultrasound beam. A powerful advantage of this technique is the ability to estimate the velocity of flow from the Doppler shift frequency.Vascular Surgical Procedures: Operative procedures for the treatment of vascular disorders.Leg: The inferior part of the lower extremity between the KNEE and the ANKLE.Laser Therapy: The use of photothermal effects of LASERS to coagulate, incise, vaporize, resect, dissect, or resurface tissue.Iliac Vein: A vein on either side of the body which is formed by the union of the external and internal iliac veins and passes upward to join with its fellow of the opposite side to form the inferior vena cava.Umbilical Veins: Venous vessels in the umbilical cord. They carry oxygenated, nutrient-rich blood from the mother to the FETUS via the PLACENTA. In humans, there is normally one umbilical vein.Mesenteric Veins: Veins which return blood from the intestines; the inferior mesenteric vein empties into the splenic vein, the superior mesenteric vein joins the splenic vein to form the portal vein.Renal Veins: Short thick veins which return blood from the kidneys to the vena cava.Ecchymosis: Extravasation of blood into the skin, resulting in a nonelevated, rounded or irregular, blue or purplish patch, larger than a petechia.Sclerotherapy: Treatment of varicose veins, hemorrhoids, gastric and esophageal varices, and peptic ulcer hemorrhage by injection or infusion of chemical agents which cause localized thrombosis and eventual fibrosis and obliteration of the vessels.Angioplasty, Laser: A technique utilizing a laser coupled to a catheter which is used in the dilatation of occluded blood vessels. This includes laser thermal angioplasty where the laser energy heats up a metal tip, and direct laser angioplasty where the laser energy directly ablates the occlusion. One form of the latter approach uses an EXCIMER LASER which creates microscopically precise cuts without thermal injury. When laser angioplasty is performed in combination with balloon angioplasty it is called laser-assisted balloon angioplasty (ANGIOPLASTY, BALLOON, LASER-ASSISTED).Vascular Grafting: Surgical insertion of BLOOD VESSEL PROSTHESES, or transplanted BLOOD VESSELS, or other biological material to repair injured or diseased blood vessels.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Popliteal Artery: The continuation of the femoral artery coursing through the popliteal fossa; it divides into the anterior and posterior tibial arteries.Hepatic Veins: Veins which drain the liver.Venous Valves: Flaps within the VEINS that allow the blood to flow only in one direction. They are usually in the medium size veins that carry blood to the heart against gravity.Polytetrafluoroethylene: Homopolymer of tetrafluoroethylene. Nonflammable, tough, inert plastic tubing or sheeting; used to line vessels, insulate, protect or lubricate apparatus; also as filter, coating for surgical implants or as prosthetic material. Synonyms: Fluoroflex; Fluoroplast; Ftoroplast; Halon; Polyfene; PTFE; Tetron.Femoral Artery: The main artery of the thigh, a continuation of the external iliac artery.Sclerosing Solutions: Chemical agents injected into blood vessels and lymphatic sinuses to shrink or cause localized THROMBOSIS; FIBROSIS, and obliteration of the vessels. This treatment is applied in a number of conditions such as VARICOSE VEINS; HEMORRHOIDS; GASTRIC VARICES; ESOPHAGEAL VARICES; PEPTIC ULCER HEMORRHAGE.Muscle, Smooth, Vascular: The nonstriated involuntary muscle tissue of blood vessels.Sumatriptan: A serotonin agonist that acts selectively at 5HT1 receptors. It is used in the treatment of MIGRAINE DISORDERS.Angioscopy: Endoscopic examination, therapy or surgery performed on the interior of blood vessels.Radial Artery: The direct continuation of the brachial trunk, originating at the bifurcation of the brachial artery opposite the neck of the radius. Its branches may be divided into three groups corresponding to the three regions in which the vessel is situated, the forearm, wrist, and hand.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Subclavian Vein: The continuation of the axillary vein which follows the subclavian artery and then joins the internal jugular vein to form the brachiocephalic vein.Axillary Vein: The venous trunk of the upper limb; a continuation of the basilar and brachial veins running from the lower border of the teres major muscle to the outer border of the first rib where it becomes the subclavian vein.Splenic Vein: Vein formed by the union (at the hilus of the spleen) of several small veins from the stomach, pancreas, spleen and mesentery.Aneurysm: Pathological outpouching or sac-like dilatation in the wall of any blood vessel (ARTERIES or VEINS) or the heart (HEART ANEURYSM). It indicates a thin and weakened area in the wall which may later rupture. Aneurysms are classified by location, etiology, or other characteristics.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Thoracic Arteries: Arteries originating from the subclavian or axillary arteries and distributing to the anterior thoracic wall, mediastinal structures, diaphragm, pectoral muscles, mammary gland and the axillary aspect of the chest wall.Postoperative Complications: Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.Cerebral Veins: Veins draining the cerebrum.Blood Vessel Prosthesis: Device constructed of either synthetic or biological material that is used for the repair of injured or diseased blood vessels.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.Ischemia: A hypoperfusion of the BLOOD through an organ or tissue caused by a PATHOLOGIC CONSTRICTION or obstruction of its BLOOD VESSELS, or an absence of BLOOD CIRCULATION.Reoperation: A repeat operation for the same condition in the same patient due to disease progression or recurrence, or as followup to failed previous surgery.Endothelium, Vascular: Single pavement layer of cells which line the luminal surface of the entire vascular system and regulate the transport of macromolecules and blood components.Endoscopy: Procedures of applying ENDOSCOPES for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. transluminal, to examine or perform surgery on the interior parts of the body.Tibial Arteries: The anterior and posterior arteries created at the bifurcation of the popliteal artery. The anterior tibial artery begins at the lower border of the popliteus muscle and lies along the tibia at the distal part of the leg to surface superficially anterior to the ankle joint. Its branches are distributed throughout the leg, ankle, and foot. The posterior tibial artery begins at the lower border of the popliteus muscle, lies behind the tibia in the lower part of its course, and is found situated between the medial malleolus and the medial process of the calcaneal tuberosity. Its branches are distributed throughout the leg and foot.Retinal Vein: Central retinal vein and its tributaries. It runs a short course within the optic nerve and then leaves and empties into the superior ophthalmic vein or cavernous sinus.Venous Thrombosis: The formation or presence of a blood clot (THROMBUS) within a vein.Azygos Vein: A vein which arises from the right ascending lumbar vein or the vena cava, enters the thorax through the aortic orifice in the diaphragm, and terminates in the superior vena cava.Brachiocephalic Veins: Large veins on either side of the root of the neck formed by the junction of the internal jugular and subclavian veins. They drain blood from the head, neck, and upper extremities, and unite to form the superior vena cava.Varicose Ulcer: Skin breakdown or ulceration caused by VARICOSE VEINS in which there is too much hydrostatic pressure in the superficial venous system of the leg. Venous hypertension leads to increased pressure in the capillary bed, transudation of fluid and proteins into the interstitial space, altering blood flow and supply of nutrients to the skin and subcutaneous tissues, and eventual ulceration.Phlebitis: Inflammation of a vein, often a vein in the leg. Phlebitis associated with a blood clot is called (THROMBOPHLEBITIS).Vasoconstrictor Agents: Drugs used to cause constriction of the blood vessels.Stents: Devices that provide support for tubular structures that are being anastomosed or for body cavities during skin grafting.Lower Extremity: The region of the lower limb in animals, extending from the gluteal region to the FOOT, and including the BUTTOCKS; HIP; and LEG.Groin: The external junctural region between the lower part of the abdomen and the thigh.Ultrasonography, Doppler, Color: Ultrasonography applying the Doppler effect, with the superposition of flow information as colors on a gray scale in a real-time image. This type of ultrasonography is well-suited to identifying the location of high-velocity flow (such as in a stenosis) or of mapping the extent of flow in a certain region.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Coronary Angiography: Radiography of the vascular system of the heart muscle after injection of a contrast medium.Blood Vessel Prosthesis Implantation: Surgical insertion of BLOOD VESSEL PROSTHESES to repair injured or diseased blood vessels.Ligation: Application of a ligature to tie a vessel or strangulate a part.Phlebography: Radiographic visualization or recording of a vein after the injection of contrast medium.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Retinal Vein Occlusion: Blockage of the RETINAL VEIN. Those at high risk for this condition include patients with HYPERTENSION; DIABETES MELLITUS; ATHEROSCLEROSIS; and other CARDIOVASCULAR DISEASES.Venous Pressure: The blood pressure in the VEINS. It is usually measured to assess the filling PRESSURE to the HEART VENTRICLE.Internal Mammary-Coronary Artery Anastomosis: Direct myocardial revascularization in which the internal mammary artery is anastomosed to the right coronary artery, circumflex artery, or anterior descending coronary artery. The internal mammary artery is the most frequent choice, especially for a single graft, for coronary artery bypass surgery.Ultrasonography, Interventional: The use of ultrasound to guide minimally invasive surgical procedures such as needle ASPIRATION BIOPSY; DRAINAGE; etc. Its widest application is intravascular ultrasound imaging but it is useful also in urology and intra-abdominal conditions.Arterial Occlusive Diseases: Pathological processes which result in the partial or complete obstruction of ARTERIES. They are characterized by greatly reduced or absence of blood flow through these vessels. They are also known as arterial insufficiency.Norepinephrine: Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.Embolic Protection Devices: Vascular filters or occlusive devices that provide mechanical protection of the distal end organ from blood clots or EMBOLISM-causing debri dislodged during ENDOVASCULAR PROCEDURES.Thigh: The portion of the leg in humans and other animals found between the HIP and KNEE.Methiothepin: A serotonin receptor antagonist in the CENTRAL NERVOUS SYSTEM used as an antipsychotic.Embolism: Blocking of a blood vessel by an embolus which can be a blood clot or other undissolved material in the blood stream.Recurrence: The return of a sign, symptom, or disease after a remission.Methoxamine: An alpha-1 adrenergic agonist that causes prolonged peripheral VASOCONSTRICTION.Lysergic AcidVasoconstriction: The physiological narrowing of BLOOD VESSELS by contraction of the VASCULAR SMOOTH MUSCLE.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Transplantation, Autologous: Transplantation of an individual's own tissue from one site to another site.Tunica Intima: The innermost layer of an artery or vein, made up of one layer of endothelial cells and supported by an internal elastic lamina.Constriction, Pathologic: The condition of an anatomical structure's being constricted beyond normal dimensions.Inguinal Canal: The tunnel in the lower anterior ABDOMINAL WALL through which the SPERMATIC CORD, in the male; ROUND LIGAMENT, in the female; nerves; and vessels pass. Its internal end is at the deep inguinal ring and its external end is at the superficial inguinal ring.Arteries: The vessels carrying blood away from the heart.Thrombophlebitis: Inflammation of a vein associated with a blood clot (THROMBUS).Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Catheterization, Peripheral: Insertion of a catheter into a peripheral artery, vein, or airway for diagnostic or therapeutic purposes.Paresthesia: Subjective cutaneous sensations (e.g., cold, warmth, tingling, pressure, etc.) that are experienced spontaneously in the absence of stimulation.Thrombosis: Formation and development of a thrombus or blood clot in the blood vessel.Arteriovenous Shunt, Surgical: Surgical shunt allowing direct passage of blood from an artery to a vein. (From Dorland, 28th ed)Fascia: Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests MUSCLES, nerves, and other organs.Stockings, Compression: Tight coverings for the foot and leg that are worn to aid circulation in the legs, and prevent the formation of EDEMA and DEEP VEIN THROMBOSIS. PNEUMATIC COMPRESSION STOCKINGS serve a similar purpose especially for bedridden patients, and following surgery.Hyperplasia: An increase in the number of cells in a tissue or organ without tumor formation. It differs from HYPERTROPHY, which is an increase in bulk without an increase in the number of cells.Arteriovenous Fistula: An abnormal direct communication between an artery and a vein without passing through the CAPILLARIES. An A-V fistula usually leads to the formation of a dilated sac-like connection, arteriovenous aneurysm. The locations and size of the shunts determine the degree of effects on the cardiovascular functions such as BLOOD PRESSURE and HEART RATE.Catheter Ablation: Removal of tissue with electrical current delivered via electrodes positioned at the distal end of a catheter. Energy sources are commonly direct current (DC-shock) or alternating current at radiofrequencies (usually 750 kHz). The technique is used most often to ablate the AV junction and/or accessory pathways in order to interrupt AV conduction and produce AV block in the treatment of various tachyarrhythmias.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.Ergotamines: A series of structurally-related alkaloids containing the ergotaman backbone structure.Receptors, Serotonin: Cell-surface proteins that bind SEROTONIN and trigger intracellular changes which influence the behavior of cells. Several types of serotonin receptors have been recognized which differ in their pharmacology, molecular biology, and mode of action.Polyethylene Terephthalates: Polyester polymers formed from terephthalic acid or its esters and ethylene glycol. They can be formed into tapes, films or pulled into fibers that are pressed into meshes or woven into fabrics.