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Atherosclerosis is a disease characterized by the deposition of fatty substances called plaques in the walls of medium and large arteries. Depending on which arteries are affected, it can lead to leg pain, erectile dysfunction, cardiovascular disease and heart attack or stroke. It is the main cause of death in developed countries.
The disease often starts in childhood and the arteries become clogged over many years, initially without symptoms.
Mechanism of the disease
High blood pressure, high cholesterol, smoking, diabetes, sedentary life style, hormone status and age are all risk factors for atherosclerosis. These factors conspire to cause tears to the lining of the medium and large arteries, which results in fatty deposits, inflammation, and ultimately narrowing of the afflicted arteries. High blood pressure provides the shear force to produce tears in the fragile endothelium, the lining of the arteries. Cholesterol migrates into these torn sections when concentrations of LDL, or low density lipoprotein are high. Smoking has a direct toxic effect on the arterial wall, causing an inflammatory response. Exercise modifies many of these risk factors, ultimately lowering the inflammatory response of the arterial walls. Hormones, especially the presence of estrogen, has a healing effect on the arterial walls. The resident cells interpret this as an intrusion, "call for help", and inflammation results. Immune cells called monocytes circulating in the blood enter the artery wall, turn into macrophages and ingest the LDL particles, thereby turning into large "foam cells". The inflammation also causes a fibrous cap to be formed between the fatty deposits and the artery. These capped fatty deposits (called atheromas) narrow the blood vessel. This can lead to narrowing (stenosis) of the artery. The atheromas are fragile. When they rupture, a partial blockage can be quickly converted into a complete obstruction, resulting in a heart attack or stroke, depending on which artery is obstructed.
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