Dictionary

angiokeratoma corporis diffusum universale See Fabry disease.

angioneurotic edema, hereditary See angioedema, hereditary.

angiopathy Disease of the arteries, veins, and capillaries. There are two types of angiopathy: microangiopathy and macroangiopathy. In microangiopathy, the walls of small blood vessels become so thick and weak that they bleed, leak protein, and slow the flow of blood. For example, diabetics may develop microangiopathy with thickening of capillaries in many areas, including…

angioplasty A procedure in which a balloontipped catheter is used to enlarge a narrowing in a coronary artery caused by arteriosclerosis. Also known as percutaneous transluminal coronary angioplasty (PTCA). See also arteriosclerosis.

angiosarcoma A form of tissue cancer (sarcoma) that arises in the lining of blood vessels. Angiosarcomas tend to be aggressive, recur locally, and spread widely. Predisposing factors include lymphedema (as from a radical mastectomy), radiotherapy, foreign materials (such as steel and plastic) in the body, and environmental agents (such as arsenic solutions used to spray…

angiostatin A fragment of a protein, plasminogen, that is involved in blood clotting. Angiostatin is normally secreted by tumors, and it appears to halt the process of developing new blood vessels, which is necessary to tumor development.

angiotensin A family of peptides that constrict blood vessels. Narrowing the diameter of the blood vessels causes blood pressure to rise.

angiotensin converting enzyme See ACE.

angle-closure glaucoma Increased pressure in the front chamber of the eye due to blockage of its normal circulation of fluid. When the iris retracts and thickens (when the pupil of the eye is wide open), it blocks the drainage pathway for fluid in the eye. This causes the pressure in the eye to soar, which…

anhidrosis Lack of sweating. Anhidrosis creates a dangerous inability to tolerate heat.

anisocoria A condition in which the left and right pupils of the eyes are not of equal size. The size of the pupil determines how much light is let into the eye. With anisocoria, the larger pupil lets more light enter the eye. There are many causes of anisocoria, including eye injury or infection and…

anisocytosis Excessive inequality in the size of the red blood cells. Anisocytosis is apparent on a blood smear examined under a microscope.