What are they?
A heart attack occurs when the muscle of the heart cannot get sufficient oxygen-containing blood for it to function. Angina pectoris (a tight chest pain that comes on exertion am goes) is often the earliest sign that something is wrong. In this condition there is insufficient blood getting to the heart muscles, especially on exertion, and the person complains of tightness in the chest as the heart muscle goes into cramp.
A heart attack is like a very severe bout of angina. Sometimes the loss of blood supply is sufficiently severe to kill off a part of the heart’s muscle, and less commonly the damage from a shortage of blood is so severe that it causes almost instant death.
The heart finds itself in this lethal condition as a result of a lifetime’s abuse which causes a progressive narrowing of the arteries (atherosclerosis) that supply the heart with oxygen. Blood clots may obstruct the arteries further.
Heart disease is now the prime killer in the western world; although in the US death rates have fallen by a quarter over the last fifteen years. Given that much of this improvement is caused by lifestyle changes it makes sense to look at heart attacks as substantially preventable. Historic evidence and evidence from populations who migrate from one country to another also strongly suggest that mankind doesn’t have to suffer from coronary artery disease and heart attacks.
There are compelling reasons for rejecting a fatalistic view that heart attacks cannot be prevented. We still have a lot to learn about heart disease, but it does seem clear that it is affected by lifestyle. We have seen that the coronary-artery death rates in the US and Australia have fallen dramatically over the last fifteen years. This improvement pre-dates the widespread use of coronary care units and coronary bypass surgery and even the widespread use of drugs for combating high blood pressure. The fall in heart disease has, however, coincided with a considerable reduction in both cigarette consumption and consumption of saturated fats. However, things are not quite as simple as this suggests, because heart-attack rates are still high in Sweden despite their wealth of medical technology and falling cigarette and fat consumption, and rates in American women are falling despite their rise in cigarette consumption.
What causes them?
No one knows exactly what ultimately causes heart attacks but several fairly clear-cut ‘risk factors’ have been established after vast and complicated studies worldwide.
• Smoking. Several studies have shown the link between smoking and heart disease. A study of particular interest looked at British doctors who stopped smoking between 34 and 55 years of age. It found that their coronary death rate fell by half over five years compared with doctors who continued to smoke. Stopping after 55 appeared to make much less difference. The degree of risk with smoking is related to the number of cigarettes smoked. Filter cigarettes are probably not protective. Cigarettes act along with the contraceptive pill to increase the risk of heart disease in young women twenty fold.
• High blood pressure. Many studies have found that reducing raised blood pressure, provided the treatment is begun in middle age, reduces mortality from strokes, heart failure and kidney failure. There is some evidence that anti-hypertensive drugs reduce mortality from heart attacks.
• High blood fats. The fats in the blood are many and take different forms. They all come originally from the digestion of dietary fat. The fractions of fats that seem to be of greatest significance in heart disease are the lipoproteins. High density lipoproteins (HDLs) appear to protect against heart disease, whereas low density lipoproteins (LDLs) seem to be harmful in this respect. The balance of these two types of lipoproteins can be altered by what we eat.
• Exercise. Studies show that those who take regular, vigorous exercise tend to have fewer heart attacks, though the evidence is not so clear-cut as is that on smoking, high blood pressure and dietary fats.
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