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What is a Heart Attack?
The heart is a muscular organ that pumps blood through the body at an average of 72 times per minute. The coronary arteries are responsible for supplying oxygen and nutrients to the heart muscle. A temporary decrease in blood supply can cause the muscle to "starve" for oxygen and result in chest discomfort or angina. A prolonged total loss of supply can cause irreversible damage of the heart muscle and produce a heart attack.
The human heart can experience prolonged starvation or angina before the affected muscle dies and turns into scar tissue. Scar tissue reduces a muscle's power to pump. That portion of the heart becomes stiff, moves sluggishly, and decreases the ability of the left ventricle (major pumping chamber of the heart) to efficiently pump blood to the body. The symptoms of chest pain preceding a heart attack can last from several minutes to a few hours.
The majority of heart attacks occur when a blockage plaque "ruptures" or develops a crack on the inner aspect of the blood vessel. A clot develops at this site and then grows to completely block the channel of the artery. This cuts off blood supply to the heart muscle supplied by that artery and results in a heart attack.
Progression of Coronary Artery Blockage
The inner lining of the normal coronary artery is smooth and free of blockages or obstructions.
Lipids or fatty substances are deposited as fatty streaks. The streaks are only minimally raised and do not produce any obstruction.
The increased buildup of fatty material, or atheroma, begins to encroach upon the inner channel and starts to interfere with the free flow of blood through the coronary artery.
Additional deposits lead to a bulky atheroma that begins to encroach further into the channel of the coronary artery. Fibers begin to grow into the atheroma causing harder plaques.
The plaque may rupture and release soft fatty contents. A blood clot may occur. If the clot causes a partial blockage, the patient may develop increasing chest pain.
If the blood clot totally blocks off flow of the coronary artery to the heart muscle, a heart attack usually results.
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