Factors affecting the development of coronary heart disease.

Gemma Brayne December 2002

Homework

“Factors affecting the development of coronary heart disease”

Coronary heart disease has two principal forms; these are angina and heart attacks. They both occur because the arteries carrying blood to the heart muscle become blocked or narrowed, usually by a deposit of fatty substances, a process known as atherosclerosis. (source 4) Angina is a severe pain in the chest brought on by exertion and relieved by rest. A heart attack is due to obstruction of a coronary artery either as a result of atherosclerosis or a blood clot, this is where part of the heart muscle is deprived of oxygen and dies.

Cigarette smoking, raised blood cholesterol and high blood pressure are the high risk factors leading to Coronary heart disease. With cigarette smoking being the "most important of the known modifiable risk factors for Coronary heart disease", (according to the US Surgeon General). A cigarette smoker has two to three times the risk of having a heart attack than a non-smoker. If both of the other main risk factors are present then the chances of having a heart attack can be increased eight times. At least 80% of heart attacks in men under 45 are thought to be due to cigarette smoking. At this age, heavy smokers have 10 to 15 times the rate of fatal heart attacks of non-smokers. Even light smokers are at increased risk of the disease. A study in the USA found that women who smoked 1-4 cigarettes a day had a 2.5-fold increased risk of fatal coronary heart disease. (source 2)Other factors include being male, age, having close relative who have had heart attacks being overweight, taking to little exercise, having high blood pressure and eating too much salt or saturated fat or too little fibre.

The relation between fat intake and the risk of coronary heart disease is not fully understood, however it does seem clear though that a high level of saturated fats and cholesterol in the diet is associated with an increased risk of coronary heart disease. (source 1)

The risk of coronary atherosclerosis increases with age (source 3), but evidence suggests that the condition may start to develop very early in life. About four out of five people who die of coronary heart disease are age 65 or older. At older ages, women who have heart attacks are more likely than men ...

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Women before menopause rarely suffer from heart disease this is because the hormone oestrogen present in women appears to protect them. Coronary heart disease mainly afflicts adult males and manifests itself in the middle ages

Individuals with hereditary high levels of blood cholesterol are more prone to develop coronary heart disease. The risk of coronary heart disease rises as blood cholesterol levels increase. When other risk factors (such as high blood pressure and tobacco smoke) are present, this risk increases even more. A person's cholesterol level is also affected by age, sex and heredity.

Smoking tends to increase blood cholesterol levels. (source 3) Cigarette smokers also have raised fibrinogen levels and platelet counts, which make the blood stickier. Carbon monoxide attaches itself to haemoglobin much more easily than oxygen does. This reduces the amount of oxygen available to the tissues. All these factors make smokers more at risk of developing various forms of atherosclerotic disease. As the atherosclerotic process progresses, blood flows less easily

through rigid and narrowed arteries and the blood is more likely to form a thrombosis. This sudden blockage of an artery may lead to a fatal heart attack, a stroke or gangrene.

High blood pressure increases the heart's workload, causing the heart to enlarge and weaken over time. It also increases the risk of stroke, heart attack, kidney failure and congestive heart failure. When high blood pressure exists with obesity, smoking, high blood cholesterol levels or diabetes, the risk of heart attack or stroke increases several times.

People who have excess body fat especially if a lot of it is in the waist area are more likely to develop heart disease and stroke even if they have no other risk factors. Obesity increases the strain on the heart, raises blood pressure and blood cholesterol and triglyceride levels, and lowers cholesterol levels. It can also make diabetes more likely to develop. As DNA determines the sizes of the arteries themselves it is probable that characteristics of the heart are passed on to offspring.

Regular exercise aids a healthy circulation, and the physically inactive are more at risk from heart disease. Also sleep disturbances and stress are predictors of angina, infraction and death due to heart attacks.

Other diseases such as diabetes and high blood pressure increase the risk of coronary disease. Diabetes seriously increases the risk of developing cardiovascular disease. Even when glucose levels are under control, diabetes greatly increases the risk of heart disease and stroke. About two-thirds of people with diabetes die of some form of heart or blood vessel disease.

Higher doses of oestrogen and progestin, increase a woman's risk of heart disease and stroke, especially in older women who smoked heavily. Newer, lower-dose oral contraceptives carry a much lower risk of cardiovascular disease, except for women who smoke or have high blood pressure.
If a woman taking oral contraceptives has other risk factors, her risk of developing blood clots and having a heart attack goes up. It rises even more after age 35.