What is Ischaemic Heart Disease? (IHD)
Ischaemic Heart Disease (coronary artery disease or CAD) is a condition in which atheroma (fatty deposits) builds up in the linings of the walls of the coronary arteries. This causes a narrow artery and reduced blood flow to the heart muscle. This process can occur in other arteries of the body. Important arteries which, if affected can have medical consequences, are the carotid arteries in the neck, (which supply blood to the brain), and the femoral /popliteal arteries in the legs. In these situations a bruit (noise) may be heard over the area affected (i.e. carotid or femoral arteries), through a stethoscope.
Atheroma at a certain point, results in obstruction to the blood flow of the coronary arteries, which leads to the inability to provide adequate oxygen to the cardiac muscle, therefore an inability to meet demand. Therefore when the heart has to work harder (i.e. in exercise, or in certain medical conditions, such as hyperthyroidism or anaemia insufficient blood reaches the heart muscle. The muscle is then said to be ischaemic. Ischaemia can also occur from coronary artery spasm, or when the heart is enlarged from increased strain, such as in high blood pressure (hypertension) or tightness at the root of the main blood vessel leading from the heart (aortic stenosis).
In practice, a reduction in coronary artery diameter by 50% or more, on coronary arteriogram is judged significant, and will most likely cause symptoms of angina.
Myocardial Ischaemia is manifested in central chest pain, causing stable angina, unstable angina and myocardial infarction (MI).