Dictionary

aneuploidy A condition in which a person has one or a few chromosomes above or below the normal chromosome number. For example, three copies of chromosome 21, which is characteristic of Down syndrome, is a form of aneuploidy.

aneurysm A localized widening (dilatation) of an artery, a vein, or the heart. At the point of an aneurysm, there is typically a bulge. The wall of the blood vessel or organ is weakened and may rupture.

aneurysm, abdominal aortic A balloon-like swelling in the wall of the aorta within the abdomen. This swelling weakens the aorta’s wall and, because of the great volume of blood flowing under high pressure in the aorta, it can rupture. An abdominal aortic aneurysm is monitored by ultrasound. Surgery is often recommended if the aneurysm is…

aneurysm, aortic An aneurysm of the largest artery in the body, the aorta, involving that vessel in its course above the diaphragm (thoracic aortic aneurysm) or, more commonly, below the diaphragm (abdominal aortic aneurysm). Because of the volume of blood flowing under relatively high pressure within the aorta, a ruptured aneurysm of the aorta is…

aneurysm, arterial An aneurysm involving an artery.

aneurysm, arteriosclerotic An aneurysm that occurs because a vessel wall is weakened by arteriosclerosis. Also known as atherosclerotic aneurysm. See also arteriosclerosis.

aneurysm, berry A small aneurysm that looks like a berry and classically occurs at the point at which a cerebral artery departs from the circular artery (the circle of Willis) at the base of the brain. Berry aneurysms frequently rupture and bleed.

aneurysm, brain An aneurysm of a blood vessel in the brain, usually due to a defect in the vessel at birth or from high blood pressure. Rupture of the aneurysm causes a sudden severe headache, often with nausea, vomiting, decreased consciousness, and can be life threatening.

aneurysm, cardiac An outpouching of an abnormally thin portion of the heart wall. Cardiac aneurysms tend to involve the left ventricle because the blood there is under the greatest pressure.

aneurysm, dissecting An aneurysm in which the wall of an artery rips (dissects) longitudinally. This occurs because bleeding into the weakened wall splits the wall. Dissecting aneurysms tend to affect the thoracic aorta. They are a particular danger in Marfan syndrome.

aneurysm, fusiform An aneurysm that is shaped like a spindle and widens an artery or a vein.

aneurysm, miliary A tiny, millet-seed–sized aneurysm that tends to affect minute arteries in the brain and, in the eye, the retina.