How Coronary Artery Disease Damages Your Heart

The heart needs oxygen-rich blood to function. Coronary arteries transport oxygen to the heart muscle. If the flow of oxygenated blood is compromised (a condition known as ischemia), heart muscle tissue can become damaged. Ischemia is the medical term for impaired blood flow to any part of the body. Coronary ischemia can lead to serious health risks such as a heart attack.

Atherosclerosis is the most common cause of coronary heart disease. Atherosclerosis is the build-up of fatty 'plaques' along blood vessel walls. Atherosclerotic plaques are a mixture of fats, calcium, cholesterol and other waste products.

    

As atherosclerosis progresses, plaques build up on the walls of arteries and cause vessel narrowing. As blood flow through the coronary arteries becomes restricted, 
the heart's available oxygen supply becomes limited. Atherosclerosis is a progressive disease: plaques develop over decades.

Arteries narrowed by plaques can still transport oxygen and blood, and can function well enough if the heart is at rest. Coronary heart disease symptoms typically develop when the heart exerts itself, either through physical or emotional stress. Plaque-clogged coronary arteries cannot provide sufficient oxygen to the over-worked heart, and chest pain, angina, or a heart attack may occur.

Heart Attacks and Exercise Any type of exercise or physical labor causes the heart to work harder to pump oxygen-rich blood throughout the body. The harder the heart works, the more oxygen it requires. Coronary heart disease and ischemia decrease the amount of oxygen available to the heart, increasing the chance of a heart attack. For instance, approximately 1,200 people die of heart attacks every year while shoveling snow. This heavy labor places great strain on the heart, and if coronary artery disease is present the heart may not get enough oxygen to meet its demands. Although this is an extreme example, it demonstrates how physical exertion can lead to a heart attack.

Plaque rupture is one of the main triggers of a heart attack. Atherosclerotic plaques contain a "soft" core that is encased in a hard outer layer. When a coronary artery constricts or "spasms", the outer shell of the plaque can crack or rupture, leading to an inflammatory response at the rupture site. This inflammation causes a clot to form. The size of the clot depends on the size of the rupture. Large blood clots may completely block the artery, causing a heart attack. Smaller blood clots may also break free of plaques and travel to smaller arteries where they may cause further blockages.

Heart Attacks and Emotional Stress Emotional stress can place as great a strain on the heart as physical exercise. A heart attack may occur during a high stress business meeting, a heated argument, or from the stress of losing a loved one. In the sixty days immediately after the World Trade Center attacks on September 11, 2001, the New York Methodist Hospital treated 35 percent more heart attack victims than during the sixty-day period before the attacks.