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.
