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.
Quick GuideHeart Disease: Causes of a Heart Attack
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Last Editorial Review: 7/1/2016