Atheroma

An atheroma, or atheromatous plaque, is an abnormal accumulation of material in the inner layer of an arterial 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 lumen of the artery, narrowing it and restricting blood flow. Atheroma is the pathological basis for the disease entity atherosclerosis, a subtype of arteriosclerosis. For most people, the first symptoms result from atheroma progression within the heart arteries, most commonly resulting in a heart attack and ensuing debility. The heart arteries are difficult to track because they are small (from about 5 mm down to microscopic), they are hidden deep within the chest and they never stop moving. Additionally, all mass-applied clinical strategies focus on both minimal cost and the overall safety of the procedure. Therefore, existing diagnostic strategies for detecting atheroma and tracking response to treatment have been extremely limited. The methods most commonly relied upon, patient symptoms and cardiac stress testing, do not detect any symptoms of the problem until atheromatous disease is very advanced because arteries enlarge, not constrict, in response to increasing atheroma. It is plaque ruptures, producing debris and clots which obstruct blood flow downstream, sometimes also locally (as seen on angiograms), which reduce/stop blood flow. Yet these events occur suddenly and are not revealed in advance by either stress tests or angiograms. The healthy epicardial coronary artery consists of three layers, the tunica intima, media, and adventitia. Atheroma and changes in the artery wall usually result in small aneurysms (enlargements) just large enough to compensate for the extra wall thickness with no change in the lumen diameter. However, eventually, typically as a result of rupture of vulnerable plaques and clots within the lumen over the plaque, stenosis (narrowing) of the vessel develops in some areas.