The walls of the arteries carrying blood to the heart become lined with fatty deposits. This restricts the flow of blood and therefore the supply of oxygen to the heart muscle. A brief narrowing of the coronary artery causes blood to stop flowing through the artery temporarily. When the spasm stops, the artery and blood flow return to normal. Heart valve abnormalities.
Heart rhythm disturbances.
An excess of red blood cells causes the blood to thicken. Some thyroid conditions. Angina is more likely to occur when increased demands are placed on the heart, as with exercise, emotional upset, exposure to cold air, and digestion of a big meal. However, angina may also occur at rest or even during sleep. The procedure for diagnosing angina depends on the severity of the symptoms.