Myocardial infarction (MI) or acute myocardial infarction (AMI), commonly known as a heart attack, is the interruption of blood supply to part of the heart, causing heart cells to die. This is most commonly due to occlusion (blockage) of a coronary artery following the rupture of a vulnerable atherosclerotic plaque, which is an unstable collection of lipids (fatty acids) and white blood cells (especially macrophages) in the wall of an artery. The resulting ischemia (restriction in blood supply) and oxygen shortage, if left untreated for a sufficient period of time, can cause damage or death (infarction) of heart muscle tissue (myocardium). Cause: It is usually caused by reduced blood flow in the coronary artery. Conditions that may lead to Myocardial Infarction:
Coronary Thrombosis or embolism
Acute severe infection, such as pneumonia, can trigger myocardial infarction. A more controversial link is that between Chlamydophila pneumoniae infection and atherosclerosis. While this intracellular organism has been demonstrated in atherosclerotic plaques, evidence is inconclusive as to whether it can be considered a causative factor. Treatment with antibiotics in patients with proven atherosclerosis has not demonstrated a decreased risk of heart attacks or other coronary vascular diseases Risk Factors:
Race - Cardiovascular disease is the leading cause of morbidity and mortality among African American, Hispanic, and white populations in the United States. 2.
Family History – family history of ischemic heart disease (IHD) 3.
Age - Men acquire an independent risk factor at age 45, Women acquire an independent risk factor at age 55; in addition individuals acquire another independent risk factor if they have a first-degree male relative (brother, father) who suffered a coronary vascular event at or before age 55. Another independent risk factor is acquired if one has a first-degree female relative (mother, sister) who suffered a coronary vascular event at age 65 or younger. 4.
Gender - A male predominance in incidence exists up to approximately age 70 years, when the sexes converge to equal incidence. Premenopausal women appear to be somewhat protected from atherosclerosis, possibly owing to the effects of estrogen. 5.
Sedentary lifestyle – which is related to obesity
Obesity - defined by a body mass index of more than 30 kg/m², or alternatively by waist circumference or waist-hip ratio 8.
Hyperhomocysteinemia - high homocysteine, a toxic blood amino acid that is elevated when intakes of vitamins B2, B6, B12 and folic acid are insufficient. 9.
Stress - occupations with high stress index are known to have susceptibility for atherosclerosis. 10.
Alcohol - Studies show that prolonged exposure to high quantities of alcohol can increase the risk of heart attack 11.
Calcium deposition is - another part of atherosclerotic plaque formation. Calcium deposits in the coronary arteries can be detected with CT scans. Several studies have shown that coronary calcium can provide predictive information beyond that of classical risk factors. 12.
High blood pressure
Many of these risk factors are modifiable, so many heart attacks can be prevented by maintaining a healthier lifestyle. Physical activity, for example, is associated with a lower risk profile. Non-modifiable risk factors include age, sex, and family history of an early heart attack (before the age of 60), which is thought of as reflecting a genetic predisposition There are two basic types of acute myocardial infarction:
Transmural - associated with atherosclerosis involving major coronary artery. It can be subclassified into anterior, posterior, or inferior. Transmural infarcts extend through the whole thickness of the heart muscle and are usually a result of complete occlusion of the area's blood supply. •
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