Angina (also called angina pectoris) is chest pain that appears when the muscle cells of the heart don't get enough blood to properly carry out their pumping function. The lack of blood supply is most likely to cause pain during physical activity, when the heart pumps fastest and needs the most oxygen. Stopping the activity normally relieves the pain. This may help to distinguish angina from other types of chest pain.
Most of the time, angina is caused by coronary artery disease (CAD). The coronary arteries are the heart muscle's blood and oxygen supply. In CAD, the coronary arteries become narrowed by fatty, fibrous deposits. This means that less blood can pass through them. During exercise or exertion, the cells in the heart (the myocardium) may need more oxygen (and therefore more blood) than the coronary arteries can handle. As these cells are forced to work without enough oxygen, the nervous system complains by sending pain signals to the brain.
When tissue doesn't get the oxygen it needs, this is called ischemia. Angina is usually caused by myocardial ischemia (not enough oxygen in the heart muscle). This isn't the same as myocardial infarction (heart attack). Infarction means permanent cell death caused by long-lasting and severe ischemia. In angina, the cells aren't usually so starved of oxygen that they die. This is why rest or medication is usually effective in relieving the pain.
Heart attacks are normally brought on by events that completely block blood flow in a coronary artery. These events may include travelling blood clots or peeling off of fatty plaques inside the arteries. In angina, there's no sudden blockage, but the artery has become so narrow that it cannot carry the blood needed to handle the demands of strenuous exercise. This usually means it has narrowed to less than half of its original width. It follows that people who suffer from angina are at higher risk of heart attack. For unknown reasons, angina seems to have a better prognosis in women than in men.
Risk factors for angina are basically the same as risk factors for coronary artery disease. They include:
Not all cases of angina are due to CAD. A minority of cases are caused by spasms in coronary arteries that constrict them enough to seriously reduce blood flow. This can be caused by drugs, especially cocaine. In most such cases, however, the cause is unknown. This condition, known as variant angina, isn't usually a sign of high heart attack risk on its own, but it generally occurs in people who also have coronary artery disease.
The pain of angina comes from the heart, but it's not generally felt exactly over the heart. The most common focus of pain is under the sternum (breastbone), midway between the breasts or pectoral muscles.
Often the pain is not localized to just the sternum and it spreads, commonly down the left arm but also to the back, sides, upper abdomen, right arm, neck, jaw, or even the teeth. Sometimes the pain can occur in these places without occurring in the chest. Any pain in these areas that occurs during exercise and improves with rest should be evaluated by a doctor.
Not everyone with ischemia will experience angina. If there is no angina, it is referred to as "silent ischemia." More commonly, however, people will experience chest pain.
The pain isn't a sudden, shooting, or stabbing type. It's often described as either a dull ache, pressure, heaviness, or a crushing sensation. Pain that comes and goes over a few seconds is also unlikely to be angina, which is steady and often predictable.
Angina is often predictable in the sense that a pattern may emerge after a few attacks. Some people will come to learn that a certain level of exertion is likely to trigger pain. In most cases, the pain will start when expected and slowly ease when exertion is stopped. It is often worse when exertion follows a meal, in cold weather, and in times of emotional stress. Not all angina is predictable.
Unstable angina is the name given to chest pain that: