Causes of heart disease

Coronary heart disease (CHD) is usually caused by a build-up of fatty deposits on the walls of the coronary arteries. The fatty deposits, called atheroma, are made up of cholesterol and other waste substances.
The build up of atheroma on the walls of the coronary arteries makes the arteries narrower and restricts the flow of blood to the heart. This process is called atherosclerosis. Your risk of developing atherosclerosis is significantly increased if you:

• smoke,
• have high blood pressure,
• have a high blood cholesterol level,
• do not take regular exercise,
• have a thrombosis, and
• have diabetes.

Other risk factors for developing atherosclerosis include:

• being obese or overweight, and
• having a family history of heart attack or angina.

For men, the likelihood of developing atherosclerosis is increased if you have a close family member (father or brother) who has had a heart attack or angina before the age of 55. For women, the risk is increased if you have a close family member (mother or sister) who has had a heart attack or angina before the age of 65.

Cholesterol

Cholesterol is a fat that is made by the liver from the saturated fat that we eat. Cholesterol is essential for healthy cells, but if there is too much in the blood it can lead to coronary heart disease.
Cholesterol is carried in the blood stream by molecules called lipoproteins. There are several different types of lipoproteins, but two of the main ones are low-density lipoproteins (LDL) and high-density lipoproteins (HDL).
LDL, often referred to as 'bad cholesterol', takes cholesterol from the liver to the cells. LDL cholesterol tends to build up on the walls of the coronary arteries, increasing your risk of heart disease. HDL, often referred to 'good cholesterol', carries cholesterol away from the cells and back to the liver, where it is broken down or passed from the body as a waste product.
Normally, the blood contains about 70% of LDL, but the amount will vary from person to person. However, if your LDL cholesterol level is too high, the HDL will not be able to remove it sufficiently.
The total amount of cholesterol in the blood can range from 3.6-7.8mmol/litre (milli-molecules per litre). A level above 6mmol/litre is considered to be high, and a risk factor for arterial disease. Government advice recommends a target total blood cholesterol level of less than 5.

High blood pressure

Hypertension (high blood pressure) puts a strain on your heart and can lead to coronary heart disease.
Blood pressure is measured at two points during the blood circulation cycle. The systolic pressure is a measure of your blood pressure as the heart contracts and pumps blood out. The diastolic pressure is a measure of your blood pressure when your heart is relaxed and filling up with blood.
Blood pressure is measured in terms of millimetres of mercury (mmHg). When you have your blood pressure measured, the systolic pressure is the first, higher number to be recorded. The diastolic pressure is the second, lower number to be recorded. High blood pressure is defined as a systolic pressure of 140mmHg or more, or a diastolic pressure of 90mmHg or more.

Smoking

Smoking is a major risk factor. Carbon monoxide (from the smoke) and nicotine both put a strain on the heart by making it work faster. They also make it more likely that your blood will clot. Other chemicals in cigarette smoke damage the lining of your coronary arteries, leading to furring of the arteries. Around 20% of CHD-related deaths in men and 17% in women are attributable to smoking.

Thrombosis

A thrombosis is a blood clot within an artery (or a vein). If a thrombosis occurs in a coronary artery (coronary thrombosis), it will cause the artery to narrow, increasing your chance of having a heart attack.
A coronary thrombosis occurs when blood turns from liquid form to solid in one of the heart's arteries. The blood clot prevents the blood supply from reaching the heart muscle. Coronary thrombosis usually happens at the same place as where atherosclerosis is forming (furring of the coronary arteries).