The human heart.

Atherosclarosis

• This is a condition when the large arteries of the body become hardened and narrowed by the build up of deposits inside the artery wall.
• These deposits are known as atheroma/atheromata or plaque.
• Atherosclerosis is usually only found in adults.

This is thrombosis in the left anterior descending coronary artery opened longitudinally here over the surface of the heart. This is another complication of atherosclerosis.

Coronary Atherosclerosis (Elastic Stain).

Atheroma

• These are deposits of mainly cholesterol and other fatty materials from the blood plasma.
• These deposits build up inside the artery wall of large arteries.

• When atheroma build up in the coronary arteries, this condition and its associated effects is known as Coronary Heart Disease (CHD)  
• Atheroma build up is thought to begin in areas of the arteries, which have been damaged in some way.
• The damage may be caused by hypertension or smoking.

Coronary heart disease

• Coronary heart disease starts when plaque begins building up on the interior lining of the coronary artery walls.
• As the plaque increases the area for blood flow diminishes.
• If the process is allowed to continue, the risk of a blood clot forming or getting logged in the artery increases.
• Eventually a complete blockage could occur

What is angina?

• This can occur by pain in the chest region
• Narrowing of the coronary arteries and their inability to supply enough oxygen to heart muscle causes this pain.
• Prominent during exercise.

What is a myocardial infarction?

• This is known as a heart attack.
• This occurs when parts of the heart are starved of oxygen and glucose.
• Without oxygen and glucose the muscle tissue cannot respire
• Thus there is no ATP for contraction of the muscle fibres therefore the heart fails to contract properly.

Development of a thrombus

• A thrombus is an internal blood clot
• This can be formatted if atheroma deposits in artery wall rapture, exposing underlying connective tissue, to which blood platelets ate attracted and stick.
• These platelets cause other platelets to stick to them by changing their nature and shape, these gradually form a thrombus

This is thrombosis in a coronary artery. Such a thrombus severely narrows or occludes the lumen and can produce a sudden ischemic event. "Sudden death" as well as infarction can occur.

• A thrombus can completely obstruct the artery, preventing blood flow to areas of tissue, once formed.
• A thrombus may also detach itself from the artery wall and enter circulation.
• This is known as an embolus, these clots may block parts of the body such as the brain causing a stroke.

Risk factors

• CHD is said to be a multi-factorial disease.
• None of these risk factors are sufficient to bring about the disease on their own
• They act over a long period of time, and some of these factors are avoidable, however some are not i.e. gender.

Genetic

• Genetic predisposition results in high cholesterol levels even when fat intake is low.

Smoking

• Chemicals in cigarette smoke are linked to artery damage and formation of atheroma.

Hypertension

• This can damage walls of arteries and ay play a role in initiating atheroma formation.

Exercise

• Exercise helps to prevent obesity and may reduce levels of Low Density Lipoproteins in the blood

Age

• CHD is much more common in people over 40, although the accumulation of atheroma may begin in childhood

Gender

• CHD is much more common in men than women in middle age.

Diet

• These factors include high fat leading to high levels of cholesterol in blood plasma, also low fibre, high sugar, and high salt intake which is linked with raised blood pressure.