Angina pectoris, or simply angina, refers to chest pain or discomfort caused by reduced
blood flow to the heart, in a condition known as myocardial ischemia.
Angina is described as a squeezing pain or heaviness in the chest, which may also spread
to the neck, arms, shoulders and back; or in the stomach area, particularly after meals.
Women are more likely to experience a burning sensation or tenderness instead of squeezing
pain.
Angina is not the same as heart attack.
It is associated with transient ischemia of the heart without permanent damage, while
heart attack is when a patch of the heart muscle dies from lack of oxygen.
But having angina significantly increases the risks for heart attacks, especially when
left untreated.
Angina is most commonly caused by the narrowing of one or more coronary arteries that supply
the heart.
This can result from a fixed obstruction by cholesterol plaques, or a temporary constriction
due to blood vessel spasms.
Angina can also be caused by anemia, when the flow is adequate, but the blood does not
have enough red blood cells to carry oxygen.
There are several types of angina.
Stable angina, the most common form, is usually caused by a fixed obstruction, a plaque.
Stable angina is predictable, with familiar pain patterns, and typically prompted by physical
exertion, when the heart requires more oxygen than it can get from narrowed vessels.
Factors that constrict blood vessels or increase blood pressure, such as emotional stress,
cold temperatures or heavy meals, may also induce angina.
Stable angina does not happen at rest, when the reduced flow is sufficient for the low
demand of the heart.
It usually subsides when the inducer is removed and responds well to medications.
Unstable angina, on the other hand, may occur unexpectedly, even at rest, with a changed
pattern from the usual stable angina.
It is more severe, lasts longer, does not respond to rest or medications, and is often
the sign that a plaque has ruptured or a clot has formed.
Unstable angina is a medical emergency as it often precedes a heart attack.
Electrocardiograms of patients with obstructive angina commonly show ST-segment depression
during attacks.
Diagnosis is confirmed with stress test, where patients are monitored while exercising.
The site of obstruction can be detected with imaging techniques, such as angiography.
It appears, however, that a significant number of patients with stable angina symptoms have
more or less normal coronary arteries on angiograms.
These cases are now recognized as microvascular angina (Cardiac syndrome X), where the problem
lies not in the large coronary arteries, but their tiny branches, and is therefore undetectable
by angiography.
Microvascular angina is much more common in women than in men.
Variant angina (Prinzmetal angina), a less common type, is caused by vascular spasms
of coronary arteries.
Variant angina can occur during rest, usually at certain times of the day, often at night.
Emotional stress, smoking and use of cocaine are known triggers.
Variant angina is often severe, but responds well to medications.
Diagnosis is by presence of ST-segment elevation during attacks, and provocative testing with
drugs that induce coronary artery spasms (ergonovine, acetylcholine).
Treatment of angina aims to relieve symptoms, reduce frequency of future anginas, but most
importantly, reduce risks of heart attacks.
Apart from lifestyle changes to modify risk factors, treatment options include a number
of medications and surgical procedures.
Nitroglycerin, a potent vasodilator, is most effective for acute anginal attacks.
Long-lasting nitrates, antiplatelet drugs (aspirin…), beta-blockers, and calcium channel
blockers can be prescribed to prevent future anginas.
Several revascularization procedures are available to restore normal blood supply to the heart.
Coronary angioplasty makes use of a balloon, and sometimes a stent, to widen the affected
artery.
Coronary bypass uses a graft to create an alternative route for blood to flow beyond
the site of blockage.