Heavy cigarette smokers are more likely to develop atherosclerosis (4), as the likelihood of fatty deposits developing on the inner lining of the arteries is greater (5). This is due the presence of nicotine and carbon monoxide in cigarettes. Nicotine causes hormones such as adrenalin to be released which constricts arteries and makes the heart beat faster, causing the blood to get stickier and more likely to clot and an increase in blood pressure to take place. If the coronary artery has already become furred up with atheroma, the stickier blood may create a clot too. Carbon monoxide also seems to increase the likelihood of a clot forming and it restricts oxygen transfer in the blood as it reacts with haemoglobin instead of oxygen at a time when the nicotine is making the heart work harder and more oxygen is needed. Therefore, overall these clots could block the lumen of the coronary artery (6).
A high blood glucose level is a direct link to atherosclerosis as excess cholesterol “can form plaques in blood vessels leading to blockages in the arteries” (1). A person's cholesterol level is also affected by age, sex, heredity and diet (7).
Diet is an important controllable factor as a diet with low fat content and less cholesterol can lead to lower blood cholesterol levels and reduce the chances of CHD developing (4). An unhealthy diet is also linked to the possibility of obesity, which also encourages CHD developing. It increases the stress on the heart and arteries and increases the chances of high blood pressure and high blood cholesterol levels, as more blood has to be pumped around a bigger body at a higher pressure. Obesity can also lead to diabetes, which is another factor affecting of CHD (4) (8). Exercise is another important link here as it improves circulation, reduces the likelihood of obesity and it lowers the heart rate and blood pressure and improves insulin utilization in diabetics (4) (8).
The final controllable factor is alcohol consumption, too much can raise blood pressure and cause irregular heartbeats. It can also contribute to obesity (7).
However, there are numerous factors that can cause and affect CHD, which are uncontrollable. Gender is an important one, as adult males seem to suffer more from CHD (4). It is believed that female hormones (especially oestrogen) offer resistance to some aspects of CHD and so during menopause, research shows that women suffer less from CHD than men. However, after menopause, after the age of 65, the death rate of women from CHD is the same as for men (6). Age is another uncontrollable factor and the risk of CHD increases with increasing age. The condition may start to develop early in life but as age increases, problems such as high blood cholesterol and high blood pressure start to build up and take their toll (4) (6).
Children of CHD sufferers are likely to develop the disease too as heredity can be a factor of CHD (4). This is due to problems such as obesity being able to pass down generations (7). Also as DNA determines the size of arteries too, it is probable that a family with smaller arteries or smaller lumens are more susceptible to having blocked arteries (10). As well as family history, ethnic background can also affect the chances of developing CHD. It has been discovered without explanation that certain races, due to their body shape maybe, are less likely to develop CHD whereas others, such as people of black origin are more likely to have higher blood pressure and develop CHD (7) (6).
There are other factors that affect CHD too. If a person suffers other diseases especially diabetes, he is more likely to develop CHD (4). This is true as 80% of people with diabetes die of some form of heart disease (10). This may be due to the fact that the factors affecting diabetes are similar to those affecting CHD (such as weight, blood cholesterol and blood pressure). Also diabetics have raised levels of fibrinogen in their blood making it more likely to clot and hence cause thrombosis (6). Diabetics also have raised blood triglyceride levels and reduced HDL levels. This increases the likelihood of cholesterol being deposited in the coronary arteries.
Other more minor factors linked with CHD include stress levels, socio-economic disadvantages, and psychological and personality factors. The involvement of the latter factors has been investigated with a study in Milan where 47% of people with coronary heart disease were firstborn compared to 29% of the general population and the likely reason is because those who are firstborn tend to have Type-A personalities (this includes people who are competitive, aggressive and rushed) (11).
As shown, there are various factors affecting CHD in different ways but is clear that most factors, especially the major ones, are linked to each other and can lead to one another. Surveys and studies have identified most of these factors but not all have been explained and this hinders the quest for successful remedies. But for research and development, “the possibility of intervening early in the atherosclerosis disease process and preventing CHD is likely to become an important issue” (1).
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