A number of factors are known or believed to be involved in development of atherosclerosis, and hence cardiovascular disease. Some are more important than others and usually several act together to bring it about. The three most important are diet, hypertension (high blood pressure) and smoking.

Diet: Atheroma contains fats and cholesterol, and it has been shown clearly that experimental animals fed on a high fat diet develop diseased arteries. In countries such as Greece and Japan where the average diet is relatively low in fat, cardiovascular disease is much less common. The main problem is caused by saturated fats which cause a rise in blood cholesterol levels. In 1992 the UK government recommended that the population from saturated fatty acids should be reduced from 17% (proportion in 1990) to no more than 11% by 2005 (a 35% reduction). A 12% reduction in total fat was also proposed (from about 40% to 35% of food energy). On the other hand, polyunsaturated f atty acids, found in unsaturated fats, are thought to help reduce cholesterol levels in blood and are therefore beneficial to health.

Hypertension (High Blood Pressure): Raised blood pressure can considerably increase the chance of developing cardiovascular disease. It has been shown that men under the age of 50 years with a blood pressure of 170/100 are twice as likely to die of coronary heart disease as men with normal blood pressure of about 120/80. High blood pressure itself is associated with a number of different factors, including stress, obesity, smoking, drinking excessive amounts of alcohol and lack of exercise. There is also a genetic predisposition in some people. Some of these factors can obviously be avoided by changes in lifestyle.

Drug known as β-blockers can be used to reduce hypertension. The hormone adrenaline has an excitatory effects on the body. It binds to specific receptors known as α- and β-receptors in its target organs. Β-blockers block the β-receptors, thus inhibiting the action of adrenaline and reducing heart rate. The same drugs are used to treat angina because they reduce the need for oxygen in the heart muscle.

Smoking: Heavy smokers are more likely to develop cardiovascular diseases. For example, people under the age of 45 years who smoke more than 25 cigarettes a day are 15 times more likely to die of heart disease than non-smokers. Nearly 40% of cardiovascular deaths re due to smoking. Smoking increase atherosclerosis and decreases the ability to remove blood clots that build up at atheromatous plaques.

The effects of smoking re many and complex.

Smoking is the largest single cause of premature death in Britain. More than one third of the extra deaths caused by smoking are due to cardiovascular disease.

Physical exercise: Many studies have shown that the more a person is physically active at work or during their leisure time, the less chance they have of suffering from cardiovascular disease. The effects of suffering from cardiovascular diseases.

Gender: Death rates from cardiovascular disease in women are less than half those for men and women rarely suffer from it before the menopause. There is a protective effect from the female sex hormones and a harmful effect from the male hormone testosterone. After the menopause women show and increase in blood fats and a sharp increase in rates of cardiovascular disease.
Lipids are insoluble in plasma and are therefore carried in a combined form with other molecules. In particular they are combined with protein to form spherical particles called Lipoproteins. The size and density of these particles varies. Two common types are the low density and high density Lipoproteins. The size and density of these particles varies. Two common types are the low density and high density lipoproteins (LDLs and HDLs respectively). HDLs contain 21%cholesterol while LDLs contain 55% cholesterol. Generally speakingm the higher t he amount of HDLs and the lower the amount of LDLs in the blood, the better for health. LDLs tend to stickto artery walls and unload their fats, contributing to atheroma. In males, HDL levels tend to drop at puberty and LDL levels gradually increase with age. This is thought to be due to testosterone. Oestrogen on the other hand increases HDLs and therefore tends to protect women between puberty and menopause. They still get heart disease but on average about 10 years later than men.

Heredity: If one parent suffers from premature coronary heart disease then the risk of a man suffering a myocardial infarction is doubled. If both parents suffered, the risk is increased by a factor of five. This indicates that there could be a genetic predisposition to heart disease. It is anticipated that the genes responsible will be identified fairly soon and tests may become available to identify those at risk.

Stress: There is great difficulty in defining stress and quantifying it. However, there is general agreement that psychological and emotional stress is often an important factor in triggering attacks of angina or even a myocardial infarction.

Age: Arteriosclerosis appears to be an inevitable consequence of ageing and this increase the risk of cardiovascular disease.