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What is coronary artery disease?

Coronary artery disease is a type of heart disease. The coronary arteries are blood vessels that carry blood and oxygen to the heart muscle. When these arteries become clogged with fatty deposits called plaque, it is called coronary artery disease (CAD). Coronary artery disease is sometimes called coronary heart disease (CHD). Clogged arteries can keep the heart

from getting enough blood and oxygen and can cause chest pain (angina). If a blood clot forms, it can suddenly cut off blood flow in the artery and cause a heart attack.

Plaque forms in the arteries over many years in a process called atherosclerosis. One cause of plaque in the arteries is too much cholesterol in the blood. As plaque builds up, the artery opening gradually narrows and becomes clogged. The artery can also become less elastic (called "hardening of the arteries").

coronary artery disease is a chronic process that begins during adolescence and slowly progresses throughout life. Independent risk factors include a family history of premature coronary artery disease, cigarette smoking, diabetes mellitus, hypertension, hyperlipidemia, and obesity. These risk factors accelerate or modify a complex and chronic inflammatory process that ultimately manifests as fibrous atherosclerotic plaque.

The most widely accepted theory of atherosclerosis holds that the process represents an attempt at healing in response to endothelial injury. The first step in the atherosclerotic process is the development of fatty streaks, which contain atherogenic lipoproteins and macrophage foam cells. These streaks form between the endothelium and the internal elastic lamina. Over time, an intermediate lesion made up of an extracellular lipid core and layers of smooth muscle and connective tissue matrix eventually forms a fibrous cap. The edge of the fibrous cap (the "shoulder" region) plays a critical role in the development of acute coronary syndromes. The shoulder region is the site where most plaques lose their integrity or rupture. Plaque rupture exposes the underlying thrombogenic core of lipid and necrotic material to circulating blood. This exposure results in the platelet adherence, aggregation, and progressive luminal narrowing that are associated with acute coronary syndromes.

The most common coronary artery disease is that which blocks arteries with cholesterol and fat. The blockage starts with a small injury on the inside wall of the coronary artery. The injury attracts blood clotting elements and cholesterol. In time, the cholesterol builds up, just like a blockage in a pipe. If the artery is blocked, even part way, the heart muscle may not get enough blood. This can cause chest pain or angina. If a narrow part of the artery is blocked with a small blood clot, no blood passes through. When a coronary artery is completely blocked, the heart muscle that depends on it may die. This causes a heart attack.

Limitation of blood flow to the heart causes ischemia (cell starvation secondary to a lack of oxygen) of the myocardial cells. When myocardial cells die from lack of oxygen, this is called a myocardial infarction (commonly called a heart attack). It leads to heart muscle damage, heart muscle death and later scarring without heart muscle regrowth.

Myocardial infarction usually results from the sudden occlusion of a coronary artery when a plaque ruptures, activating the clotting system and atheroma-clot interaction fills the lumen of the artery to the point of sudden closure. The typical narrowing of the lumen of the heart artery before sudden closure is typically 20%, according to clinical research completed in the late 1990s and using IVUS examinations within 6 months prior to a heart attack. High grade stenoses exceeding 75% blockage, such as detected by stress testing, were found to be responsible for only 14% of acute heart attacks. The events leading up to plaque rupture are only partially understood. Myocardial infarction is also caused, far less commonly, by spasm of the artery wall occluding the lumen, a condition also associated with atheromatous plaque and CHD.

More information on coronary artery disease

What is coronary artery disease? - Coronary artery disease is a heart disease condition that results when the coronary arteries are narrowed or occluded, caused by atherosclerotic deposits of fibrous and fatty tissue.
What're the symptoms of coronary artery disease? - In most patients, the most common symptom of coronary artery disease is the type of chest pain called angina, or angina pectoris.
What're the risk factors for coronary artery disease? - Risk factors of coronary artery disease include advancing age, male sex, and a family history of early coronary artery disease.
How is coronary artery disease diagnosed? - The diagnosis of coronary artery disease requires a careful history, physical examination, and an electrocardiogram (ECG).
What're the treatments for coronary artery disease? - Medical treatment for coronary artery disease generally includes medications, risk factor reduction, along with close follow-up with your health care team.
How is coronary artery disease prevented? - Prevention of coronary artery disease centers on the modifiable risk factors: blood sugar, lipoprotein transport systems, obesity, homocysteine, hypertension.
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