Coronary heart disease

The coronary arteries supply the heart muscle itself with oxygenated blood. In coronary heart disease (CHD), fatty deposits build up inside these arteries, narrowing them and reducing blood flow to the heart muscle. This can cause chest pain and, if a coronary artery becomes blocked, a heart attack.

A stent is a small tube inserted into a narrowed coronary artery to hold it open and restore blood flow.

Pros: works immediately, and recovery is relatively quick. Cons: it's a surgical procedure with risks such as infection or bleeding, and the artery can narrow again over time.

Statins are drugs that reduce the level of cholesterol in the blood, slowing down the rate at which fatty deposits form in the arteries.

Pros: non-invasive (taken as a pill), and can reduce the risk of other health problems linked to high cholesterol. Cons: effects build up slowly rather than acting immediately, some people experience side effects, and they must usually be taken long-term.

Faulty heart valves can be replaced with biological valves, taken from a human or animal donor (often a pig), or mechanical valves, made from man-made materials.

Biological valves behave naturally like a human valve, but can wear out over time and may need replacing again. Mechanical valves can last a lifetime, but the patient must take blood-thinning drugs long-term to stop blood clots forming on the valve.