Heart attack, medically known as Myocardial Infarction, is the sudden stoppage of the heart due to death or damage to a large part of the heart muscles known as myocardium. It is widely acknowledged that heart related conditions (cardiovascular diseases) are the number one cause of death and disability in the United States and most parts of the civilized world, today. And sudden death, from heart attack is by far the most common consequence of cardiovascular diseases.
We have all seen someone, seemingly healthy days or hours before, suddenly slump and die. This is the kind of death or disability that heart attack visits on its victims. Of the numerous types of cardiovascular conditions, the one that is most likely to lead to a heart attack is what is known as Coronary Heart Disease (CHD) or more appropriately, Coronary Artery Disease (CAD).
Coronary arteries are the vessels (arteries) that carry oxygen-rich blood to the heart muscles or myocardium. So, as the name implies, Coronary Artery Disease is a condition that affects the coronary arteries (i.e. arteries of the heart). This condition is characterized by the slow and gradual buildup of fatty deposits (fat streaks, plaques or atheromatous streaks) in the walls of the coronary arteries. Initially, these atheromatous streaks/plaques expand into the walls of the arteries, but subsequently, they start building up and growing into the lumen of the affected arteries, narrowing such arteries and obstructing blood flow. This is known as atherosclerosis.
As the build up of the plaques continue, over the years, the plaques increase in thickness and the degree of obstruction of blood flow to the heart muscles becomes severe. Though, the buildup of the plaques takes a very long time to completely occlude the lumen of an artery and result in heart attack, however, sudden rupture of a plaque usually speeds up the process. The rupture of plaque activates the blood clotting system and the clot-plaque interaction fills the lumen of such artery to the point of sudden closure. Such sudden occlusion of a coronary artery causes irreversible death of the heart muscle supplied by that artery (myocardial infarction) and precipitates a 'heart attack' i.e. the sudden stop of heart beat.
Coronary heart disease, the commonest underlying cause of heart attack, as with several other cardiovascular conditions has been associated with a number of risk factors; however, a family history of coronary heart disease appears to be one of the strongest risk factors. Also, men are more likely to suffer a heart attack than women, though after menopause, the risk of women approaches that of men, especially with hormonal therapies, which tend to increase a woman's risk of CHD. Other risk factors include: Smoking, diabetes, hypertension, obesity (especially central or female-type obesity), a chronic sub-clinical lack of vitamin C, elevated homocysteine levels, elevated blood levels of asymmetric dimethylarginine and also importantly, sedentary or inactive lifestyle.
Beside some factors which cannot be controlled, such as hereditary and gender, prevention of CHD and hence, heart attack, is usually achieved through the modification of risk factors. Leading an active life style with frequent exercise, cessation of smoking, maintaining a low-fat, low-calorie diet and decreasing blood cholesterol levels, especially Low density lipoproteins (LDL) are crucial to preventing heart attack. Exercise and healthy diet have been shown to have profound effect on cardiovascular risks, although, cessation of cigarette smoking can also profoundly reduce the risk of heart attack.
It is important to note that despite the increasingly growing number of deaths recorded as a result of heart related conditions, cardiovascular diseases can still be prevented, or at least delayed, in most cases, contrary to general beliefs. The increasing number of deaths recorded in most western countries is mainly due to unhealthy lifestyles; such as smoking, lack of physical activity and unhealthy eating habits; and worst still, the unwillingness to modify these lifestyles in most individuals.