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HowToPreventHeartDisease.com |
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How Much Do You Know About Heart Attack? More than a million Americans have heart attacks every year. A heart attack (or myocardial infarction) occurs when the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked and the heart cannot get sufficient oxygen. If the blood flow cannot be restored swiftly, that section of the heart muscle will die and damage permanently. Being responsible for causing heart attack for most patients, coronary heart disease is a condition in which plaque builds up inside of the coronary arteries that supply oxygen-rich blood to the heart. New studies, however, show that a person having no blockage in the heart arteries or have no risk factors for heart disease can still get a heart attack if there is an imbalance between oxygen supply and demand to the heart. According to the Third Universal Definition of myocardial infarction released in 2012, myocardial infarctions can be classified into 5 categories. Type 1 myocardial infarction covers heart attack because of coronary heart disease. Having multiple risk factors for heart disease including smoking, high cholesterol, diabetes, high blood pressure or a family history of heart disease would put one at higher risk of developing coronary heart disease. This is what is called the conventional model that has been used in the past. It includes spontaneous heart attacks resulting from the sudden blockage of the heart arteries because of plaque rupture and blood clot formation.
Second type of myocardial infarction covers heart attack in patients without any conventional risk factors but with an imbalance between oxygen supply and demand to the heart due to causes other than coronary heart disease. This can be sub-divided into 3 sub-categories. First sub-category encompasses patients who have no narrowed heart arteries and the heart attack is due solely to supply-demand imbalance. Heart attack can occur in patients, who are critically ill or undergoing major general surgery, as a result of direct toxic effects of high levels of internally produced or intravenously administered stress hormones (catecholamine). The heart rate in these patients will increase and so as the oxygen demand by the heart. This might cause the supply-demand imbalance. Thickened heart muscle caused by poorly controlled high blood pressure or inherited heart disease such as hypertrophic cardiomyopathy and physical stress can also cause the oxygen demand by the heart to raise and trigger the imbalance. Those patients who already have a blocked heart artery but the heart attack occurs due to supply-demand imbalance are covered under the second sub-category. The third sub-category refers to those who have arteries with underlying abnormal function of the artery wall. These patients can suffer sudden chest pain that is not specifically related to exertion and not related to any particular activity. Third type of myocardial infarction occurs in patients who suffer cardiac death, with symptoms showing insufficient oxygen supply to the heart muscles. Patients, who suffer an acute heart attack and die before further blood tests or other confirmatory tests can be done, are classified in this category. Fourth type of myocardial infarction belongs to heart attack patients who have blood clot formation within a heart stent, and those related to heart bypass graft surgery are covered under Type 5 myocardial infarction. A heart stent is a cylindrical metallic mesh placed inside the heart artery to open a narrowed segment. New knowledge has certainly broadened the understanding of what is defined as and what causes a heart attack in the last decade. Such findings can potentially allow doctors to take appropriate preventive measures even though supply-demand imbalance heart attacks can be more difficult to anticipate. For instance, avoidance of severe physical stress will help reduce the risk of a heart attack for people who have an abnormal thickening of the heart muscle, and taking measures to lower chances of elevation of catecholamine can help prevent heart attack for those undergoing major surgery or have critical illness that can trigger high stress hormones.
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