Acute: Severe; of short duration, as opposed to chronic.

Anastomosis:The surgical or pathological connection of two tubular structures.

Aneurysm: A ballooning out of the wall of an artery or of the heart due to weakening of the wall by disease, injury, or an abnormality present at birth.

Angiography: A diagnostic procedure in which a dye is injected into blood vessels that are then photographed using X-rays. Angiography is used to visualize the condition of arteries and veins and to confirm the presence of blood clots or other abnormalities.

Anticoagulant: An agent that prevents blood from clotting.

Arteriography: A method of X-ray viewing the inside of the arteries by injection of radiopaque contrast substance into the lumen of the arteries.

Artery: A blood vessel that carries blood from the heart to the various parts of the body.

Atherosclerosis: A type of artery disease in which the inner layers of artery walls become thick and irregular because of deposits of cholesterol and calcium. The arteries become narrowed and the flow of blood through them is reduced. A localized area of this build up is called an “atheromatous plaque” and is often referred to as hardening of the arteries. Atherosclerosis is frequently observed in the artery wall of aneurysm patients, though there is much debate as to whether or not atherosclerosis actually causes most aneurysms. In atherosclerosis, a substance called plaque forms on the lining of the blood vessel wall, weakening the wall. Seeplaque for more information.

Atrial fibrillation: The uncoordinated contractions or individual heart muscle fibers in the upper chambers of the heart. These chambers, called the atria, cannot contract in an organized fashion.

Blood clot: A mass of thickened blood formed by clotting factors in the blood. This clot can stop the flow of blood from an injury. Blood clots can form inside an artery whose walls are damaged by atherosclerotic plaques and can cause a heart attack or stroke. A blood clot and thrombosis are the same.

Bruits: Abnormal sounds or murmurs caused by turbulence and heard over blood vessels.

Cardiac: Pertaining to the heart.

Carotid artery: The major artery in the neck carrying blood to the brain. The body has a left carotid artery and a right carotid artery.

Carotid endarterectomy: Surgical removal of atherosclerotic plaque deposits from the carotid arteries.

Cerebrovascular occlusion: The obstruction or closing of a blood vessel in the brain.

Cholesterol: A type of fatty substance found in animal tissue. Cholesterol is present only in foods from animal sources, such as dairy products, meats, fish, poultry, animal fats, and egg yolks.

Chronic: Having a long duration, as opposed to acute.

CT (computer tomography): A radiographic diagnostic test often used for evaluating brain tissue and identifying whether a stroke was due to bleeding or a blockage in an artery. Also called a CAT scan. For more information, please see the Medline Plus entry for CT scan.

Diabetes mellitus: A disease in which the body does not produce or properly use insulin. Diabetes increases the risk of developing cardiovascular disease.

Diastolic blood pressure: The lowest blood pressure measurement in the arteries. It occurs when the heart muscle is relaxed between beats.

Edema: Swelling due to an abnormally large amount of fluid in body tissue.

Embolic stroke: A stroke caused by obstruction in a brain artery cause by a clot that has formed elsewhere, usually in the heart or in the carotid arteries, and has been carried through the blood stream to the brain.

Embolus: A blood clot that forms in a blood vessel in one part of the body and then is carried to another part of the body. The plural of embolus is emboli.

Hematoma: A tissue swelling filled with blood.

Hemiplegia: A paralysis of one side of the body.

Hemorrhage: Profuse bleeding from a ruptured blood vessel.

Heparin: A type of anticoagulant drug that prevents clotting by affecting the blood component fibrinogen.

High blood pressure: A chronic blood disease in which blood pressure is above its normal range of 140/90. High blood pressure increases the risk of heart disease and kidney disease and is a major risk factor for stroke. A technical term for high blood pressure is hypertension.

Hypertension: Same as high blood pressure.

Infarction: Death of tissue due to a lack of blood, usually caused by a blockage of an associated artery.

Intermittent claudication: A complex of symptoms characterized by absence of pain in a limb when at rest. The start of pain and weakness when walking is begun, intensification of the pain and weakness if exercise is continued, and the disappearance of symptoms after a brief period of rest.

Ischemia: Decreased blood flow to an organ, usually due to constriction or obstruction of an artery.

MRI (magnetic resonance imaging): A noninvasive diagnostic tool, which produces a magnetic field for examining the brain and other parts of the body.

Plaque: Plaque is formed when cholesterol, fibrous cells, and/or calcium deposit themselves in the inner lining of a blood vessel wall.

Platelets: One of the three kinds of formed elements found in the blood. Platelets aid in the clotting of the blood.

Risk factor: A condition that increases the chance of developing cardiovascular disease or stroke.

Stenosis: Narrowing or constriction of an opening or lumen, such as blood vessel.

Stent: A device used to hold a vessel open by providing support.

Stroke: The sudden interruption of the blood supply to the brain, caused either by blockage or a rupture of blood vessels.

Systolic blood pressure: The highest blood pressure measured in the arteries. It occurs when the heart contracts with each heart beat.

Thrombus: A blood clot that forms inside a blood vessel or cavity of the heart. The plural form of thrombus is thrombi.

Transcranial doppler ultrasound: A noninvasive diagnostic test that uses ultrasound technique to generate information about intracranial blood vessels. Also called TCD.

TIA (transient ischemic attack): An abnormal neurologic episode that is caused by a temporarily blocked blood vessel and leaves no permanent brain damage. Symptoms are the same as for a stroke, but are temporary, usually lasting twenty-four hours or less. They are now an important warning sign of an impending stroke and should never be ignored.

Ultrasound: Fast-frequency sound vibrations, not audible to the human ear, used in medical diagnosis.

Vascular: Pertaining to blood vessels.

Vasculitis: Inflammation of the blood vessels.

Vein: Any one of a series of blood vessels of the vascular system that carries blood from various parts of the body back to the heart.

Warfarin: A synthetic anticoagulant that works by preventing certain blood clotting agents from forming in the liver.