Atherosclerosis

Atherosclerosis is a term used to describe the accumulation of fats and lipids (molecules consisting mainly of cholesterol) that ultimately results in the formation of plaque within arteries in the body. This process can eventually result in the disruption or complete obstruction of blood flow through these arteries, causing a heart attack or stoke.

Atherosclerosis is a well-recognized process that results directly in coronary and cerebrovascular disease and, thus, cardiovascular death. It remains the major cause of death and disability in developed nations. It is estimated that one-half of all cardiovascular deaths each year are secondary to coronary artery disease and roughly 20 percent more are due to stroke. Additionally, atherosclerotic changes in blood vessels begin to occur in the first two decades of life.

As the human life span has continued to increase, so too has the prevalence of atherosclerotic disease and the comorbidities and mortality with which it is associated. Certain risk factors have been identified that put people at a higher risk for developing such changes. These include smoking (specifically tobacco products), high blood pressure, high cholesterol, diabetes, a family history of cardiac disease, and the person's age. In addition, obesity is also a risk factor for atheroclerosis and coronary artery disease. Recent research studies have suggested that obesity may accelerate the progression of coronary atherocleroris. Often atherosclerotic change due to these risks is not discovered until an acute event occurs.

Atherosclerosis typically begins with the formation of small lesions, referred to as fatty streaks, or atheromas, in the internal wall of arteries (blood vessels in the body that deliver oxygenated blood from the heart to the body). Accumulation of such fatty streaks results in a loss of mobility in the arterial wall. Further accumulation of fatty streaks results in the migration of inflammatory mediators to these sites. Invasion of the deeper layers of the arterial wall then occurs with eventual formation of atherosclerotic plaques. These plaques will eventually calcify over time and contribute to coronary artery remodeling. Such changes result in a decreased intraluminal (inner space of artery) size within arteries and a decrease in oxygenated blood flow through these blood vessels. Such changes can ultimately result in heart attack and stroke.

Atherosclerosis has not, in the past, been monitored via imaging studies such as X-ray, computerized tomography (CT) scan, or magnetic resonance imaging (MRI). Testing has usually been limited to blood samples that are used to measure a person's lipid panel. Such a panel measures the total cholesterol that is circulating, low-density lipoprotein (also known as “bad” cholesterol), high-density lipoprotein (also known as “good cholesterol”), and triglycerides (cells that store and transport fat molecules). While measures of cholesterol are useful in monitoring values on an annual basis, they have never provided an adequate internal view of plaque accumulation. With the advent of stress testing in the 1960s, physicians gained a tool for monitoring physical and electrocardiographic changes during exercise that may indicate significant atherosclerotic disease in the coronary arteries. During this same period, cardiac catheterization was perfected as a technique for gaining visual access to the anatomy of the coronary arteries.

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