How medicines work

The cardiovascular system – the heart, the blood vessels and the blood – is vital to maintaining life. Things can go wrong at all levels, from the constituents of the blood to the pipes that carry it around the body and the pump itself.

Cardiovascular disease describes a variety of conditions that affect the flow of blood to the heart. Many of them are linked to an initial problem called atherosclerosis. In atherosclerosis the lining of the arteries becomes coated with fatty substances referred to as plaque or atheroma. Atherosclerosis leads to narrowing and hardening of the arteries. It is linked to high blood cholesterol levels, obesity, lack of exercise and smoking. Atherosclerosis can lead to a number of different problems with the cardiovascular system.

• In peripheral artery disease the arteries supplying the legs become narrowed or blocked, causing pain.
• In coronary heart disease the coronary arteries supplying the heart with blood become narrowed or blocked and the heart muscle is deprived of oxygen. When the heart muscle is deprived of oxygen this leads to the pain commonly known as angina.
• In a heart attack a clot forms in a coronary artery and the blood supply to an area of the cardiac muscle is completely cut off. The muscle is rapidly damaged and dies. If the blockage is severe it may lead to cardiac arrest and death.
• Hypertension or raised blood pressure as a result of narrowed and hardened arteries increases the risk of damage to organs such as the kidney and an increased risk of strokes.

There are other types of heart problems as well. These include:

• Heart failure is when the heart fails to pump the blood effectively round the body. It is often caused when the heart muscle is weakened, when the cardiac muscles become stiffened or when heart valves become diseased or damaged and so they become leaky. It sounds dramatic, but in fact people can live with heart failure for many years, especially when supported by medication or with replacement valves.
• Arrhythmias occur when the normal rhythmic beat of the heart is lost. The atria or the ventricles may beat in a very rapid and uncoordinated way. Some types of fibrillation are treatable using medication, other types need surgery or a pace maker.