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Common names or abbreviations:
 | Mitral
Valve Defect |
| MVD |
Description or definition:
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Mitral
Valve Defect (MVD) is any defect in the valve that separates the left
atrium and the left ventricle. Depending on the defect, the
condition can range from mild to severe.
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The
left ventricle contracts and sends the blood out into the arteries to take
oxygen and nutrients to the rest of the body. The valve between the
left atrium and left ventricle is called the mitral valve. A defect
in the mitral valve generally prevents the valve from properly doing its
job to keep blood from flowing back into the left atrium when the left
ventricle contracts. This backflow of blood is called mitral
regurgitation.
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| Mitral
valve defects cause a reduced blood supply to the body. They also
cause a larger than normal volume of blood to accumulate in the left
atrium. As a result, the left atrium begins to expand or “bulge”
to accommodate this greater volume of blood. This chronic stretching
of the heart muscle fibers eventually causes the heart to beat abnormally.
The body also attempts to compensate for the reduced blood flow to the
body by increasing the heart rate and constricting blood vessels to
increase blood pressure and maintain normal body function. This
decreased blood supply causes the exercise intolerance that is commonly
observed in dogs with mitral valve defects. If the left atrium
enlarges enough, it will compress and injure the left mainstem bronchus of
the lung and cause a hacking cough. In more severe cases this
condition can lead to heart failure.
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Mitral
Valve Dysplasia:
This form of mitral valve defect is congenital (present at birth)
and is the result of abnormal development (dysplasia) of the mitral
valve. If the dysfunction is mild it may never present a
clinical problem. In moderate cases, the dog may not begin to
experience any signs or symptoms of the disease until it ages.
In the most severe cases the condition can lead to heart failure.
An older dog with asymptomatic mitral valve dysplasia is more prone
than a normal dog to develop congestive heart failure.
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Mitral
Stenosis:
This defect is caused by narrowing of the mitral valve that
separates the left atrium and the left ventricle. When the
mitral valve is narrowed, it is difficult for the blood to leave the
left atrium. Like other mitral valve defects, dogs with mitral
valve stenosis can be affected either mildly or severely. Most
dogs can live active normal lives, but with age the condition can
progressively worsen.
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Mitral
Valve Insufficiency.
This term is often used to indicate a degeneration of the mitral
valve leaflets that results in valve insufficiency (leaks) in aging
or geriatric dogs.
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| Mitral
valve prolapse (MVP):
is when the mitral valve flaps do not close properly. As
pressure builds inside the left ventricle it pushes the mitral valve
back into the left atrium which may cause a small leak. |
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Symptoms:
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Reduced
tolerance for exercise, difficulty breathing, coughing at night or when at
rest (these symptoms occur because of a build-up of fluid in the lungs),
heart murmur, abnormal heart rhythm (cardiac arrhythmia). Signs of a
gradually failing heart include fainting, weakness, or collapse.
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Diagnosis:
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Most
experienced veterinarians can diagnose a heart murmur simply by listening
with a stethoscope. If a heart murmur is detected in a young dog, an
echocardiogram (ultrasound), electrocardiograph (ECG/EKG), and
raidiographs (X Ray) should be done to confirm the diagnosis and stage the
disease. These tests can often reveal some of the changes that occur
in the heart over time, as it works harder to compensate for the
insufficiency of the mitral valve. These changes may include
enlargement of the left side of the heart, enlargement of blood vessels in
the lungs, and cardiac arrhythmias.
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Check
here for OFA heart clinics in your area:
http://www.offa.org/clinics.html
Treatment:
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Treatment
depends on the stage of heart disease and the severity of the condition.
Dogs with very mild cases may live a normal life without the need for any
veterinary intervention. Treatment may include a special
sodium-restricted diet, exercise restriction, diuretics, and medication to
support the failing heart. There are also cardiac drugs available
that may be beneficial to this condition.
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For
more information on heart disease, or if you are concerned about whether
your dog has a heart condition, contact your veterinarian.
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Links to sites about this disease:
This summary provided by:
| Jessica
in Arizona |
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