By Katherine Solem
Get answers to common questions about what causes angina (chest pain), the difference between stable angina and unstable angina, heart attack symptoms, medications for angina treatment, and how angina relates to heart disease and heart attack.
What is angina?
Angina is a type of chest pain, pressure, numbness or heaviness across the chest or behind the breastbone due to inadequate supply of oxygen to the heart muscle. Angina is a common symptom of coronary artery disease (CAD) (also called coronary heart disease) , the most common form of heart disease and the number one killer of men and women in the United States.
Coronary artery disease occurs when fatty deposits called plaque build up inside the veins that supply blood and oxygen to the heart (coronary arteries). This causes the arteries to narrow and reduces the amount of blood flowing to the heart.
When the blood flow is reduced too much, the heart muscle is starved of oxygen and begins to die or becomes damaged permanently. This is called a heart attack. Chest pain from angina is a serious concern because it can often — but not always — signal an impending heart attack.
Although, the terms angina and chest pain are often used interchangeably, you can have chest pain that is not caused by angina, such heartburn from indigestion or a tightening of the chest from asthma. (See other conditions that can cause chest pain.)
What are the different types of angina?
There are three types of angina, each of which have different symptoms and require different treatments:
- Stable angina: Stable angina is the most common type of angina. It occurs when the heart must work harder than usual, such as during physical activities, emotional distress or extreme temperatures. Stable angina occurs in a regular, predictable pattern and usually disappears with rest or medication, such as nitroglycerin. Nitroglycerin widens the blood vessels and allows more oxygen to reach the heart. Stable angina is not a heart attack, but it can indicate that a heart attack is more likely to occur in the future. Learn more about stable angina.
- Unstable angina: As its name suggests, the pain caused by unstable angina is less predictable and often occurs when resting. The pain may occur more frequently, last longer and feel more severe than stable angina and may or may not be relieved by rest or medication. Unstable angina is a sign that a heart attack may happen very soon and requires emergency medical attention. Learn more about unstable angina.
- Variant (or Prinzmetal's) angina: This is a rare type of angina, accounting for about two percent of all angina cases. Variant angina doesn't follow a predictable pattern like after exercise or stress, as stable angina does. Attacks, which can be very painful, almost always happen at rest or when sleeping, usually between the hours of midnight and 8 a.m. About two-thirds of people who have variant angina have severe coronary atherosclerosis (a constricting and hardening of the arteries due to an accumulation of plaque in the vessel wall) in at least one major vessel. The angina spasm usually occurs very close to the blockage. Learn more about variant angina.
What causes angina?
Angina is caused by a temporary lack of oxygen-rich blood to the heart muscle due to a narrowing of the arteries that carry blood to the heart. When the blood flow to an area of the heart is decreased, the supply of oxygen and nutrients to the muscle cells and the heart is reduced.
To maintain its function, the heart muscle will use alternative, less efficient forms of fuel. This causes the muscles to produce lactic acid which causes pain and discomfort around the heart.
With stable angina, severely narrowed arteries may allow enough oxygen to reach the blood when at rest, such as sitting. But physical exertion, such as running to catch the bus, makes the heart work harder and that can trigger the chest pain.
With unstable angina, blood clots partly or totally block the artery, reducing the flow of blood and oxygen to the heart, which triggers angina pain. These blood clots can form, partially dissolve and then form again later, which is what causes the chest pain to come and go unpredictably. A clot that is large enough to completely block the artery causes a heart attack.
Published: July 8, 2010