This is called ischemia. Ischemia of the heart can be compared to a cramp in the leg. When someone exercises for a very long time, the muscles in the legs cramp up because they're starved for oxygen and nutrients. Your heart, also a muscle, needs oxygen and nutrients to keep working. If its blood supply is inadequate to meet the heart muscle's needs, ischemia occurs, and you may feel chest pain or other symptoms.
Ischemia is most likely to occur when the heart demands extra oxygen.
Angina can be described as a discomfort, heaviness, pressure, aching, burning, fullness, squeezing or painful feeling. It can be mistaken for indigestion. Angina is usually felt in the chest, but may also be felt in the left shoulder, arms, neck, throat, jaw or back. Call your doctor if you begin to have new symptoms or if they become more frequent or severe. This is called silent ischemia.