What Is Coronary Microvascular Disease?
Coronary microvascular disease (MVD) affects the
heart's smallest coronary arteries. Coronary MVD occurs in the heart's tiny
arteries when:
- Plaque (plak) forms in the arteries. Plaque is
made up of fat, cholesterol (ko-LES-ter-ol), calcium, and other substances
found in the blood. It narrows the coronary arteries and reduces blood flow to
the heart muscle. As a result, the heart doesn't get the oxygen it needs. This
is known as ischemic (is-KE-mik) heart disease, or heart disease. In coronary
MVD, plaque can scatter, spread out evenly, or build up into blockages in the
tiny coronary arteries.
- The arteries spasm (tighten). Spasms of the small
coronary arteries also can prevent enough oxygen-rich blood from moving through
the arteries. This too can cause ischemic heart disease.
- The walls of the arteries are damaged or
diseased. Changes in the arteries' cells and the surrounding muscle tissues
may, over time, damage the arteries' walls.
Coronary MVD is a new concept. It's different from
traditional
coronary
artery disease (CAD). In CAD, plaque builds up in the heart's large
arteries. This buildup can lead to blockages that limit or prevent oxygen-rich
blood from reaching the heart muscle.
In coronary MVD, however, the heart's smallest
arteries are affected. Plaque doesn't always create blockages as it does in
CAD. For this reason, coronary MVD also is called nonobstructive CAD.
No one knows whether coronary MVD is the same as MVD
linked to other diseases, such as
diabetes.
Overview
Death rates from heart disease have dropped quite a
bit in the last 30 years. This is due to improved treatments for conditions
such as blocked coronary arteries,
heart
attack, and
heart
failure.
However, death rates haven't improved as much in
women as they have in men. Heart disease in men and women may differ. Many
researchers think that a drop in estrogen levels in women at menopause combined
with traditional risk factors for heart disease causes coronary MVD. Therefore,
coronary MVD is being studied as a possible cause of heart disease in women.
Diagnosing coronary MVD has been a challenge for
doctors. Most of the research on heart disease has been done on men.
Standard tests used to diagnose heart disease have
been useful in finding blockages in the coronary arteries. However, these same
tests used in women with symptoms of heart diseasesuch as chest
painoften show that they have "clear" arteries.
This is because standard tests for CAD don't always
detect coronary MVD in women. Standard tests look for blockages that affect
blood flow in the large coronary arteries. However, these tests can't detect
plaque that forms, scatters, or builds up in the smallest coronary arteries.
The standard tests also can't detect when the
arteries spasm (tighten) or when the walls of the arteries are damaged or
diseased.
As a result, women are often thought to be at low
risk for heart disease.
Outlook
Coronary MVD is thought to affect up to 3 million
women with heart disease in the United States.
Most of the information known about coronary MVD
comes from the National Heart, Lung, and Blood Institute's
WISE study
(Women's Ischemia Syndrome Evaluation). The WISE study began in 1996. Its goal
was to learn more about how heart disease develops in women.
The role of hormones in heart disease has been
studied, as well as how to improve the diagnosis of coronary MVD. Further
studies are under way to learn more about the disease, how to treat it, and its
outcomes.
September 2007
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