What Causes Angina?
Underlying Causes
Angina is a symptom of an underlying heart
condition. Angina pain is the result of reduced blood flow to an area of heart
muscle.
Coronary
artery disease (CAD) usually causes the reduced blood flow.
This means that the underlying causes of angina are
generally the same as the underlying causes of CAD.
Research suggests that damage to the inner layers of
the coronary arteries causes CAD. Smoking, high levels of fat and
cholesterol
in the blood,
high
blood pressure, and a high level of sugar in the blood (due to insulin
resistance or
diabetes) can damage the coronary arteries.
When damage occurs, your body starts a healing
process. Excess fatty tissues release compounds that promote this process. This
healing causes plaque to build up where the arteries are damaged. Plaque
narrows or blocks the arteries, reducing blood flow to the heart muscle.
Some plaque is hard and stable and leads to narrowed
and hardened arteries. Other plaque is soft and is more likely to break open
and cause blood clots.
The buildup of plaque on the arteries' inner walls
can cause angina in two ways. It can:
- Narrow the arteries and greatly reduce blood flow
to the heart
- Form blood clots that partially or totally block
the arteries
Immediate Causes
There are different triggers for angina pain,
depending on the type of angina you have.
Stable Angina
Physical exertion is the most common trigger of
stable angina. Severely narrowed arteries may allow enough blood to reach the
heart when the demand for oxygen is low (such as when you're sitting). But with
exertion, like walking up a hill or climbing stairs, the heart works harder and
needs more oxygen.
Other triggers of stable angina include:
- Emotional stress
- Exposure to very hot or cold temperatures
- Heavy meals
- Smoking
Unstable Angina
Blood clots that partially or totally block an
artery cause unstable angina. If plaque in an artery ruptures or breaks open,
blood clots may form. This creates a larger blockage. A clot may grow large
enough to completely block the artery and cause a heart attack. For more
information, see the animation in
"What
Causes a Heart Attack?"
Blood clots may form, partly dissolve, and later
form again. Angina can occur each time a clot blocks an artery.
Variant Angina
A spasm in a coronary artery causes variant angina.
The spasm causes the walls of the artery to tighten and narrow. Blood flow to
the heart slows or stops. Variant angina may occur in people with or without
CAD.
Other causes of spasms in the coronary arteries are:
- Exposure to cold
- Emotional stress
- Medicines that tighten or narrow blood vessels
- Smoking
- Cocaine use
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