Atheroma, a diseased condition affecting the walls of arteries and the valves of the heart. The arterial coats become infiltrated with cells, which subsequently undergo fatty degeneration or calcification. The elasticity and resistance of the artery are thus interfered with, and various affections may thence result, e.g. aneurism (q.v.), senile gangrene, or, if the cerebral vessels be affected, apoplexy (q.v.). Atheromatous degeneration is almost always present in old persons, but in some subjects it may occur earlier or to a greater extent than in others.