Angina pectoris (Latin for "chest constriction") is the result of a lack of oxygen supply to the heart muscle, due to a reduced blood flow around the heart's blood vessels. This lack of oxygen to the heart is known as myocardial ischemia. Angina pectoris is a common symptom of myocardial ischemia (most often chest pain). People with coronary artery disease are most often affected by angina.
Angina is the most common symptom of myocardial ischemia. It is caused by stimulation of nerve endings in the heart muscle and its blood vessels.
Pathophysiology
Increases in heart rate result in increased oxygen demand by the heart. The heart has a limited ability to increase its oxygen intake during episodes of increased demand. Therefore, an increase in oxygen demand by the heart (e.g., during exercise) has to be met by a proportional increase in blood flow to the heart.
Myocardial ischemia can result from:
a reduction of blood flow to the heart caused by the stenosis or spasm of the heart's arteries,
resistance of the blood vessels, or
reduced oxygen-carrying capacity of the blood.
Atherosclerosis (narrowing of the blood vessels) is the most common cause of stenosis of the heart's arteries and, hence, angina pectoris.
Many people with chest pain have normal or minimal narrowing of heart arteries. This has shown that resistance of the blood vessels (abnormal constriction or deficient relaxation of heart vessels) can be responsible for as much as 95% of coronary artery resistance.
Myocardial ischemia also can be the result of factors affecting blood composition, such as reduced oxygen-carrying capacity of blood, as seen with severe anemia (low number of red blood cells), or long-term smoking.
Common Cardiovascular Disorders
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