The first indication that you have coronary artery disease may be angina, which is a latin word for pain; pectoris means in the chest. It happens because the heart muscle is becoming starved of oxygen, or is becoming ischemic, as it's known technically. This usually happens during exercise or emotional arousal. It occurs because when you're exercising or angry, your heart starts pumping more blood, and hence, needs more oxygen to keep it going. The typical description of angina is a tight feeling in the middle of the chest, which comes on during exercise and goes away during rest. Sometimes it goes down one or both arms, or into the neck. In more severe cases, it can start during the night or while you're at rest. In the vast majority of cases, it signifies a partial obstruction to one or more coronary arteries, although occasionally it occurs because an artery goes into spasm.
When angina comes on and the heart is not getting enough blood, there's a telltale change in the electrocardiogram which clinches the diagnosis. This change forms the basis of the stress test, which is performed by walking on a treadmill while the electrocardiogram is recorded. Sometimes the heart may become ischemic without your feeling any pain; this is called silent ischemia and may show up on the cardiogram.
