Ischaemia is a condition where there is a decreased blood flow in the blood vessels supplying blood to the heart muscle. These results in inability to provide adequate Oxygen to heart muscle (ischaemia) and this can cause damage to the heart muscle. The commonest cause of ischaemic heart disease is atherosclerosis, in which fatty deposits (plaques) build up gradually and accumulate on the inner walls of the coronary arteries and this lead to narrowing and hardening of the blood vessels supplying blood and oxygen to the heart muscle.