The heart muscle (myocardium) receives its blood supply with oxygen and nutrients through two main arteries (coronary arteries) and their branches. Partial or total occlusion of a main coronary artery or a branch can lead to an impaired blood supply to a part of the myocardium. An incomplete occlusion of the blood supply usually causes myocardial ischaemia. However, a total occlusion can lead to death of the particular part of the myocardium (infarction). These processes are known as ischaemic heart disease.
Ischaemic heart disease can weaken the ability of the heart to pump blood throughout your body. It mainly occurs due to narrowing of the coronary arteries by fat (cholesterol) deposits in their walls. This process is known as atherosclerosis or atheroma formation.