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Revision as of 16:39, 14 January 2003
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 disfunction, 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
Cholesterol, an important component of cell membranes, travels in the blood from the liver and intestines to the tissues in the form of low density lipoprotein (LDL) particles. If the LDL concentration is too high, these particles can accumulate in the artery walls (intima) where the fat oxidizes. 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. In some cases, this can lead to complete blockage (stenosis) of the artery; more commonly, the caps eventually break and a blood clot forms at the rupture. In both cases, essential blood flow can be interrupted and heart attack or stroke can result.
Risk factors
These risk factors for atherosclerosis are known:
- having high blood concentration of LDL ("bad cholesterol") and low concentration of HDL ("good cholesterol"). HDL particles transport cholesterol from the tissues back to the liver.
- aging and being male (women are affected more after menopause)
- having close relatives who had heart disease or a stroke at a relatively young age
- having high blood pressure
- having diabetes
- tobbacco smoking
- having trouble managing stress
- being obese
- being physically inactive
- some chemicals indicating ongoing inflammation may also point to high risk
High-risk patients are given a low-fat diet, exercise and fat-lowering drugs.
Treatment
If atherosclerosis leads to symptoms, the symptoms (such as angina) can be treated. Medicines are usually the first step in treating cardiovascular diseases. Other treatments include angioplasty procedures to open up clogged arteries and surgery, such as bypass surgery.
High blood pressure, diabetes, or high blood cholesterol can be treated as well. Lowering the blood cholesterol level can slow, stop, or even reverse the buildup of plaque. Cholesterol lowering can reduce the cholesterol content in unstable plaques to make them more stable and less prone to rupture.
Some of the text on this page has been taken from the public domain document at http://www.4woman.gov/faq/atheroscle.htm
References:
- Peter Libby: Atherosclerosis: The New View, Scientific American Vol 286, No. 5, May 2002
- Merck Manual: Atherosclerosis, http://www.merck.com/pubs/mmanual/section16/chapter201/201b.htm