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.
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.
Roughly 6.3 million Americans are estimated to experience angina. Coronary artery disease is the single most common cause of death in the United States, almost one death per minute. Angina is more often the presenting symptom of coronary artery disease in women than in men. The prevalence of angina rises with an increase in age.
Most patients with angina complain of chest discomfort rather than actual pain, the discomfort is usually is described as a pressure, heaviness, squeezing, burning, or choking sensation. Anginal pain may be localized primarily in the epigastrium (upper central abdomen), back, neck, jaw, or shoulders. Typical locations for radiation of pain are arms, shoulders, and neck. Angina typically is precipitated by exertion or emotional stress, and exacerbated by having a full stomach or cold temperatures (the "4 Es": exertion, emotion, eating and extreme temperature). Pain may be accompanied by sweating and nausea in some cases. It usually lasts for about 1-5 minutes, and is relieved by rest or specific anti-angina medication. Chest pain lasting only a few seconds is normally not angina.
An attack of angina pectoris usually comes on with a sudden seizure of pain, felt at first over the region of the heart, but radiating through the chest in various directions, and frequently extending down the left arm. A feeling of constriction and of suffocation accompanies the pain, although there is seldom actual difficulty in breathing. When the attack comes on, as it often does, in the course of some bodily exertion, the sufferer is at once brought to rest, and during the continuance of the paroxysm experiences the most intense agony. The countenance becomes pale, the surface of the body cold, the pulse feeble, and death appears to be imminent, when suddenly the attack subsides and complete relief is obtained. The duration of a paroxysm rarely exceeds two or three minutes, but it may last for a longer period. The attacks are apt to recur on slight exertion, and even in aggravated cases without any such exciting cause.
Major risk factors for angina include family history of premature heart disease, cigarette smoking, diabetes, high cholesterol, and high blood pressure.
Factors associated with reducing the risk of angina include education of patients about the benefits of stopping smoking, cholesterol-lowering (low saturated fats) diet, physical activity, moderate alcohol intake (1-2 drinks per day), and periodic screening for diabetes and high blood pressure.
The main goals of treatment in angina pectoris are relief of symptoms, slowing progression of the disease, and reduction of future events, especially heart attacks. An aspirin per day has been shown to be beneficial for all patients with stable angina who have no problems with its use. Beta-blockers and nitroglycerin medication are used for symptomatic relief of angina and prevention of ischemic events.
Physicians distinguish between stable angina, which occurs during exercise or stress, and is relieved with a nitrate spray or tablet (e.g. amyl nitrate), and unstable angina, which occurs at rest, or is unrelieved by the usual medication. A patient with angina that is increasing in frequency or severity is also said to have unstable angina.
The pain can be caused by thrombi embolising and blocking of the coronary vessels, not long enough to cause a heart attack, but long enough to cause pain.
Unstable angina is very predictive of a future heart attack, and requires immediate medical attention.