In CHD, the arteries that supply the heart with oxygen and nutrients become narrowed by atherosclerosis. This restricts the supply of blood and oxygen to the heart, particularly during exertion when there are more demands on the heart muscle.
What are the symptoms of CHD?
The main symptom is angina, caused by insufficient oxygen reaching the heart muscle because of reduced blood flow.
Angina is a feeling of heaviness, tightness or pain in the middle of your chest that may extend to, or just affect, your arms (especially the left), neck, jaw, face, back or abdomen.
It's most often experienced during exertion - if you run for a bus, for example, or climb stairs. It may occur in cold weather, after a heavy meal, or when you're feeling stressed. It can subside once you stop what you're doing and rest, or take medication.

Heart attack?
Unfortunately, for many people the first indication that something’s wrong is a heart attack.
This happens when the blood supply to a part of the heart muscle is completely interrupted or stops, usually when a blood clot forms in a diseased coronary artery that's already become narrowed by atherosclerosis.
The pain of a heart attack is often severe, and is frequently described as a central, crushing type of pain - like a tight band around the chest. Unlike angina, the pain doesn't subside when you rest.
Sometimes it can be mild, and is mistaken for indigestion. Some people have a heart attack without experiencing pain.
Other heart attack symptoms include sweating, light-headedness, nausea or breathlessness which, again, aren’t alleviated by rest.
If you suspect you, or someone else, is having a heart attack, seek medical help immediately by calling 999. Modern treatments can restore the blood supply to the heart muscle. The sooner treatment is given, the less permanent damage there will be.