Coronary artery disease, the most common form of heart disease, is the leading cause of death in the United States in both men and women. The American Heart Association’s “Heart Disease and Stroke Statistics 2010 Update” reports that coronary artery disease affects nearly 13 million Americans and results in nearly 500,000 deaths annually. This disease results from the buildup of plaque in the coronary arteries, which supply blood to the heart muscle itself.
Causes
Atherosclerosis is a disease of arterial blood vessels in which plaques form on artery walls. As the Cleveland Clinic explains, when substances that circulate in the bloodstream, such as inflammatory cells, proteins, cholesterol, and calcium, start sticking to the inside of the vessel walls, they combine to form a waxy material called plaque.
Plaque deposits can accumulate and narrow blood flow in the artery. They consist of lipid, or fat, cores covered by collagen fiber caps. When a fiber cap becomes thin, these “hard plaques” can suddenly rupture, spilling their contents, resulting in blood clots that partially or completely block blood flow and cause a heart attack. These types of blockages, however, cause only about 30 percent of heart attacks.
Types
Researchers have identified two kinds of plaque: hard and soft. They have found that many people who have heart attacks do not have arteries narrowed by plaque. Many heart attacks are now known to be caused by soft or vulnerable plaques, located on an inflamed part of an artery. These plaques can burst, leading to the formation of a blood clot that can cause a heart attack.
In the February 2009 issue of “The American Journal of Pathology,” Olga Ovchinnikova writes that inflammatory cells are often observed at the site of plaque rupture. Ovchinnikova’s team found that inflammation results in the formation of soft or vulnerable plaques, which are filled with different cell types that promote blood clotting. This leads to a reduction of mature collagen, resulting in thinner caps that are more likely to rupture.
Risk Factors
A major factor contributing to arterial wall damage is a high level of LDL, or "bad" cholesterol, in the blood. At normal concentrations in the blood, LDL particles can pass in and out of the inner lining of blood vessels, but in excess, they become stuck and accumulate.
High blood pressure also contributes to the buildup of plaque by increasing the rate at which arteries harden. Cigarette smoking accelerates the progression of plaque formation by damaging artery walls and allowing cholesterol deposits to develop.
Prevention
Lifestyle changes can prevent or slow the development of coronary plaque. It's important to keep track of your blood pressure and cholesterol levels. Choosing a heart-healthy diet is vital in controlling weight, which helps keep blood pressure and cholesterol levels down. Foods high in cholesterol and saturated fat should be avoided, and quitting smoking is imperative. Regular exercise and an increased overall activity level contribute to heart health and help reduce stress.
Treatment
Several medications can improve blood flow throughout the body. These may include ACE inhibitors for treating high blood pressure, aspirin, beta-blockers, blood thinners, calcium channel blockers and cholesterol-lowering medicines called statins.
Doctors may perform angioplasty to flatten out the plaque against the arterial wall, reducing the amount of plaque and improving blood flow. This procedure often is combined with the insertion of a stent--a small, tube-shaped coil--into the affected artery to keep it open. If an artery is severely blocked, a coronary bypass operation may be needed.
References
- “The American Journal of Pathology”; T-Cell Activation Leads to Reduced Collagen Maturation in Atherosclerotic Plaques of Apoe Mice; O. Ovchinnikova; February 2009
- “Circulation”; Heart Disease and Stroke Statistics – 2010 Update; Donald Lloyd-Jones et al; 2010
- MayoClinic.com: Arteriosclerosis/Atherosclerosis
- Cleveland Clinic: Coronary Artery Disease
