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Unstable angina is a form of Acute
Coronary Syndrome (ACS), and like all ACS, unstable angina should be considered a medical
emergency. What is Unstable Angina? Angina (chest pain or chest discomfort
produced when the heart muscle is not getting enough blood flow) is
considered "unstable" when it no longer follows the predictable
patterns typical of "stable angina."
Unstable angina is called "unstable" for two reasons. First, in contrast
to stable angina, symptoms occur in a more random and unpredictable fashion.
While in stable angina, symptoms typically are brought on by exertion, fatigue,
anger, or some other form of stress, in unstable angina symptoms can (and often
do) occur without any apparent trigger. |
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In fact, unstable angina often occurs at rest, and can
even wake people from a restful sleep. Furthermore, in unstable angina,
the symptoms often persist for more than just a few minutes, and nitroglycerin
often fails to relieve the pain. |
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Unstable angina is "unstable" because
symptoms may occur more frequently than usual, without any discernable
trigger, and may persist for a long time. Second, and more importantly,
unstable angina is "unstable" because, as with all forms
of ACS, it is most often caused by the actual rupture of a plaque
in a coronary artery. |
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In unstable angina, the ruptured plaque, and the blood
clot that is almost always associated with the rupture, are producing
partial blockage of the artery. The partial blockage may take a "stuttering" pattern
(as the blood clot grows and shrinks), producing angina that comes
and goes in an unpredictable fashion.
If the clot should cause complete
obstruction of the artery (which happens commonly), the heart muscle
supplied by that affected artery is in grave danger of sustaining irreversible
damage. In other words, the imminent risk of a complete myocardial
infarction is very high in unstable angina. Obviously, such a condition
is quite "unstable," and for this reason is a medical emergency. |
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When Should You Suspect You Might have Unstable Angina? |
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Anybody with a history of coronary artery disease should
suspect unstable angina if their angina begins to occur at a markedly
lower-than-normal level of exercise, if it occurs at rest, if it persists
longer than usual, if it is more difficult to relieve with nitroglycerin,
or especially if it wakes them up at night. People without any history
of coronary artery disease can also develop unstable angina, but these
individuals seem to be at higher risk because, unfortunately, they
often don’t recognize the symptoms as being angina. |
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Symptoms of Unstable Angina |
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The classic symptoms of angina include chest pressure
or pain, sometimes squeezing or “heavy” in character, often radiating
to the jaw or left arm. Unfortunately, many patients with angina do
not have classic symptoms. Their discomfort may be very mild, and may
be localized to the back, abdomen, shoulders, or either or both arms.
Nausea, breathlessness, or merely a feeling of heartburn may be the
only symptom. |
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What this means, essentially, is that anyone middle aged
or older, especially anyone with one or more risk factors for coronary
artery disease, should be alert to symptoms that might represent angina.
If you think there is any possibility you might have unstable angina,
you need to go to your doctor, or to an emergency room, immediately. |
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How Is Unstable Angina Diagnosed? |
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Symptoms are critically important in making the diagnosis of unstable
angina, or indeed, any form of ACS. In particular, if you have one
or more of the following three symptoms, your doctor should take that
as a strong clue that one type or another of ACS is occurring: |
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Angina at rest, especially if it lasts more than
20 minutes at a time |
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New onset angina that markedly limits the patient's ability to
engage in physical activity |
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An increase in prior stable angina, with episodes that are more
frequent, longer lasting, or occur with less exertion than previously |
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| Once your doctor suspects ACS, he should immediately get an ECG and blood
tests for cardiac enzyme testing. |
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Peter Scott - Team Leader
