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 Video Resources: See the heart at work and learn more about cardiac conditions and diagnostics.
Videos courtesy of Guidant Corp.
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The human heart pumps blood through the arteries continuously throughout a person’s life. The coronary arteries carry oxygen-rich blood to the myocardium; if the flow stops, a myocardial infarction (“death of heart tissue”) occurs. This is another name for a heart attack.
Most people experience a heart attack due to atherosclerosis, or hardening of the arteries, in which plaque builds up on the artery walls. As the arteries narrow due to these cholesterol and fat deposits, blood flow is reduced. Eventually, the body’s demand for oxygen will exceed its ability to supply it, a condition known as ischemia. Prolonged ischemia due to atherosclerosis can lead to a heart attack. Although atherosclerosis is often blamed for a heart attack, it is a particular event like the formation of a blood clot on the fatty plaque that blocks the artery and causes the attack.
The severity of the heart attack is judged by how much heart muscle is involved, the length of the ischemia, and the extent of infarction.
Most heart attacks are several hours long. Approximately one-third of them occur with no previous warning signs. In fact, some people mistake a heart attack for heartburn, a less serious condition. If you suspect that you are having a heart attack, you should seek help immediately.
Heart attacks that occur without warning are usually associated with silent ischemia, random interruptions of blood flow to the heart that are pain-free. Silent ischemia gradually damages the heart tissue over time. An estimated 3 to 4 million Americans may have silent ischemia and not know it. This condition can be detected with an ECG test.
However, many people have conditions that predispose them to a heart attack. Angina, which produces chest pain similar to that of a heart attack, is marked by restricted blood flow to the heart as well. But in the case of angina, blood flow is quickly restored and the heart is not permanently damaged.
One-third of all heart attack victims die before reaching a hospital; others make it to the hospital but then suffer life-threatening complications while there. These complications include stroke, heart arrhythmias (irregular heart beats), congestive heart failure, blood clot formation, or an aneurysm.
Others recover fully from a heart attack. Although they are weakened at first, normal activities can usually be resumed within three months of the attack.
