In the brain it is called a stroke. In the coronary arteries it is particularly dangerous. A coronary thrombosis blocks off the supply of oxygen to the heart muscle. If a large part of the heart is affected, it will stop beating. This is called a cardiac arrest.
Immediate action is vital.
You have four minutes to get the heart beating again. After this time, the brain cells will die from a lack of oxygen because blood is no longer being pumped to the head. 4 Suggest why heart disease is very rare in the developing world. 5 Design a poster and think up a good slogan to persuade people to look after their hearts.