The heart is a muscle that pumps blood throughout the body.  Like other muscles, the heart needs a steady supply of oxygen to function.  Blood carries oxygen to the heart and the rest to the body through blood vessels called arteries.  In the heart, the coronary arteries supply blood and oxygen to the heart muscle.  If the heart doesn’t get enough oxygen angina or a heart attack can result.

Coronary artery disease starts when the lining of a coronary artery is damaged.  Having one or more risk factors such as smoking or high blood Cholesterol, can speed up and worsen this damage.  Over time, plaque (a fatty material composed to Cholesterol and other particles) builds up within the Artery wall.  This build-up (called Atherosclerosis) narrows the space inside the Artery.  It also makes Artery walls less able to expand.  At times when the heart needs more oxygen, the increased demand for blood cannot be met.  This can lead to Angina.

Coronary arteries wrap around the surface of the heart.  Their job is to supply the heart muscle with oxygen-rich blood.  The amount of oxygen the heart needs depends on how hard it’s working. 

For example, exercise makes the heart beat faster, increasing the muscle’s need for oxygen.  Healthy arteries can easily meet this need.  They have smooth, flexible walls that can accommodate changes in blood flow.