Atheroma
| Atheroma | |
|---|---|
| Synonyms | atheromata, atheromas |
 |
|
| Atherosclerotic plaque from a carotid endarterectomy specimen. This shows the of the common into the internal and external carotid arteries. | |
| Classification and external resources | |
| Specialty | cardiology |
| ICD-10 | I70.9 |
| ICD-9-CM | 440 |
| DiseasesDB | 1039 |
| MeSH | C14.907.137.126.307 |
An atheroma is an accumulation of degenerative material in the inner layer of an artery wall. The material consists of mostly macrophage cells, or debris, containing lipids, calcium and a variable amount of fibrous connective tissue. The accumulated material forms a swelling in the artery wall, which may intrude into the channel of the artery, narrowing it and restricting blood flow. Atheroma occurs in atherosclerosis, which is one of the three subtypes of arteriosclerosis (which are atherosclerosis, Monckeberg's arteriosclerosis and arteriolosclerosis).
In the context of heart or artery matters, atheromata are commonly referred to as atheromatous plaques. It is an unhealthy condition found in most humans.
Veins do not develop atheromata, because they are not subjected to the same hemodynamic pressure that arteries are, unless surgically moved to function as an artery, as in bypass surgery. The accumulation (swelling) is always in the tunica intima, between the endothelium lining and the smooth muscle middle layer of the artery wall. While the early stages, based on gross appearance, have traditionally been termed fatty streaks by pathologists, they are not composed of fat cells but of accumulations of white blood cells, especially macrophages, that have taken up oxidized low-density lipoprotein (LDL). After they accumulate large amounts of cytoplasmic membranes (with associated high cholesterol content) they are called foam cells. When foam cells die, their contents are released, which attracts more macrophages and creates an extracellular lipid core near the center to inner surface of each atherosclerotic plaque. Conversely, the outer, older portions of the plaque become more calcified, less metabolically active and more physically stiff over time.
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