dissecting aneurysm

aneurysm /an·eu·rysm/ (an´u-rizm) a sac formed by localized dilatation of the wall of an artery, a vein, or the heart.aneurys´mal

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aortic aneurysm  aneurysm of the aorta.

arteriosclerotic aneurysm  an aneurysm arising in a large artery, usually the abdominal aorta, as a result of weakening of the wall in severe atherosclerosis.

arteriovenous aneurysm  abnormal communication between an artery and a vein in which the blood flows directly into a neighboring vein or is carried into the vein by a connecting sac.

atherosclerotic aneurysm  arteriosclerotic a.

berry aneurysm  a small saccular aneurysm of a cerebral artery, usually at the junction of vessels in the circle of Willis, having a narrow opening into the artery.

compound aneurysm  one in which some of the layers of the wall of the vessel are ruptured and some merely dilated.

dissecting aneurysm  one resulting from hemorrhage that causes longitudinal splitting of the arterial wall, producing a tear in the intima and establishing communication with the lumen; it usually affects the aorta (aortic dissection).

false aneurysm 

1. one in which the entire wall is injured and the blood is retained in the surrounding tissues; a sac communicating with the artery (or heart) is eventually formed.

2. pseudoaneurysm.

infected aneurysm  one produced by growth of microorganisms (bacteria or fungi) in the vessel wall, or infection arising within a preexisting arteriosclerotic aneurysm.

mycotic aneurysm  an infected aneurysm caused by fungi.

racemose aneurysm  dilatation and tortuous lengthening of the blood vessels.

saccular aneurysm , sacculated aneurysm a distended sac affecting only part of the arterial circumference.

varicose aneurysm  one in which an intervening sac connects the artery with contiguous veins.

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dissecting aneurysm

n.

The splitting or dissection of an arterial wall by blood entering through a tear of the inner lining or by interstitial hemorrhage.

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dissecting aneurysm

Etymology: L, dissecare, to cut apart; Gk, aneurysma, a widening

a localized dilation of an artery, most commonly the aorta, characterized by a longitudinal separation of the outer and middle layers of the vascular wall. Aortic dissecting aneurysms occur most frequently in men between 40 and 60 years of age and are preceded by hypertension in more than 90% of cases. Blood entering a tear in the intimal lining of the vessel causes a separation of weakened elastic and fibromuscular elements in the medial layer and leads to the formation of cystic spaces filled with matrix. Dissecting aneurysms in the thoracic aorta may extend into blood vessels of the neck. Rupture of a dissecting aneurysm may be fatal in less than 1 hour. Treatment consists of resection and replacement of the excised section of aorta with a synthetic prosthesis. See also aortic aneurysm.

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dissecting aneurysm

see dissecting aneurysm.