Cardiovascular diseases

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  • Created by: Rachh
  • Created on: 08-01-13 18:00

Atheromas

Cardiovascular disease - any disease associated with the heart and blood vessels (Including aneurysms, thrombosis and myocardial infarction). Most start with atheroma formation.

Atheroma - a fibrous plaque caused by the build up and hardening of white blood cells, lipids and connective tissue.

The wall of an artery is made up of several layers. The endothelium (inner lining) is normally smooth and unbroken.
If damage occurs to the endothelium (eg by high blood pressure), white blood cells (mostly macrophages) and lipids (fat) from the blood clump together under the lining to form fatty streaks.
Over time, more white blood cells, lipids and connective tissue build up and harden to form an atheroma.

An atheroma partially blocks the lumen of the artery and restricts blood flow, causing the blood pressure to increase.

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Aneurysm

Aneurysm - a balloon-like swelling of an artery.

It starts with the formation of atheromas. Atheroma plaques damage and weaken arteries. They also narrow arteries, increasing blood pressure.
When blood travels through a weakened artery at high pressure, it may push through the inner layers of the artery through the outer elastic layer to form an aneurysm.
This aneurysm may burst, causing a haemorrhage (bleeding).

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Thrombosis

Thrombosis - the formation of a blood clot

It starts with the formation of atheromas. 
An atheroma plaque can rupture the endothelium (inner lining) of an artery. This damages the artery wall and leaves a rough surface. 
Platelets and fibrin (a protein) accumulate at the site of damage and form a blood clot (a thrombus)
This blood clot can cause a complete blockage of the artery, or it can become dislodged and block a blood vessel elsewhere in the body
Debris from the rupture can cause another blood clot to form further down the artery.

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Myocardial infarction

The heart muscle is supplied with blood by the coronary arteries. This blood contains the oxygen needed by the heart muscle cells to carry out respiration.
If a coronary artery becomes completely blocked (eg by a blood clot), an area of the heart muscle will be cut off from its blood supply, receiving no oxygen.
This causes a myocardial infarction (heart attack).

Symptoms include pain in the chest and upper body, shortness of breath and sweating.
A heart attack can cause damage and death of heart muscle. If large areas of the heart are affected complete heart failure can occur, which is often fatal.

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Coronary heart disease

Coronary heart disease - when the coronary arteries have lots of atheromas in them, which restricts blood flow to the heart.
It's a type of cardiovascular disease.
Atheromas also cause blood clots to form, which can block blood flow to the heart muscle, possibly resulting in myocardial infarction.

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Common risk factors

High blood pressure - this increases the risk of damage to the coronary artery walls. Damaged walls have an increased risk of atheroma formation, causing a further increase in blood pressure. So anything that causes high blood pressure, eg being overweight, not exercising and excessive alcohol consumption, increases the risk of CHD.

High blood cholesterol and poor diet - cholesterol is one of the main constituents of the fatty deposits that form atheromas. A diet high in saturated fat is associated with high blood cholesterol levels. A diet high in salt also increases the risk of CHD as it increases the risk of high blood pressure.

Cigarette smoking - the carbon monoxide combines with the haemoglobin and reduces the amount of oxygen carried in the blood and if the heart muscle doesn't receive enough oxygen it can lead to a heart attack. Smoking also decreases the amount of antioxidants in the blood which are important for protecting cells from damage. Fewer antioxidants means cell damage in the coronary artery walls is more likely, which can lead to atheroma formation,

Most of these factors are within our control - a person can choose to smoke, eat fatty foods etc. However, some risk factors, such as having a genetic predisposition to coronary heart disease or having high blood pressure as a result of another condition, aren't. Even so, the risk of developing CHD can be reduced by removing as many risk factors as possible.

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