Risk factors and treatment of cardiovascular diseaseEdexcel A-Level Biology A: Revision notes

A risk factor is something that increases the chance of developing a disease. It does not guarantee the disease, and several risk factors together increase the risk more than any one alone. Some can be changed (diet, smoking, inactivity, blood pressure) and some cannot (age, gender, genetics).

Risk factors are identified by studies that find a correlation between a factor and CVD. A correlation does not prove a cause, because other variables may differ between groups.

Genetics: inheriting certain alleles can raise blood cholesterol or blood pressure (for example, a family history of heart attacks at a young age).

Age: the risk rises with age because damage to the endothelium accumulates and arteries become less elastic.

Gender: men have a higher risk of CVD at a younger age than women. Before the menopause, the hormone oestrogen in women has a protective effect, for example by helping to keep cholesterol lower. After the menopause the risk to women rises.

Diet: a diet high in saturated fat raises blood cholesterol, so more cholesterol enters the artery wall and plaque forms. A diet high in salt raises blood pressure.

High blood pressure damages the endothelium, which begins atherosclerosis, and the narrowed arteries then raise the pressure further.

Inactivity makes obesity, high blood pressure and raised cholesterol more likely, whereas regular exercise lowers blood pressure and strengthens the heart.

Smoking is a major risk factor.

• Nicotine increases the heart rate and constricts blood vessels, so blood pressure rises.
• Carbon monoxide binds irreversibly to haemoglobin, reducing the oxygen carried in the blood, so the heart must work harder.
• Chemicals in smoke damage the endothelium, increasing the risk of atherosclerosis, and make platelets stickier, which increases the risk of clots.

• Antihypertensives lower blood pressure, reducing damage to arteries and the risk of stroke. Risks: blood pressure too low (dizziness, fainting) and side effects.
• Statins lower blood cholesterol, slowing plaque formation. Risks: muscle pain, liver damage.
• Anticoagulants (e.g. warfarin) reduce blood clotting, lowering the risk of thrombosis. Risk: excessive bleeding.
• Platelet inhibitors (e.g. aspirin) stop platelets sticking together, so reduce clotting. Risk: bleeding, such as stomach ulcers.

Doctors weigh these benefits against the risks for each patient, and lifestyle changes are recommended alongside drugs.