Mitral
Valve Prolapse
Mitral
valve prolapse, also known as click-murmur syndrome,
Barlow's syndrome, balloon mitral valve, or
floppy valve syndrome, is the bulging of one or
both of the mitral valve flaps (leaflets) into
the left atrium during the contraction of the
heart. One or both of the flaps may not close
properly, allowing the blood to leak backward
(regurgitation). This regurgitation may result
in a murmur (abnormal sound in the heart due to
turbulent blood flow). Mitral regurgitation (backward
flow of blood), if present at all, is generally
mild.
Mitral
valve prolapse is the most common form of valvular
heart disease, occurring in 2 percent to 6 percent
of the population.
The
mitral valve is located between the left atrium
and the left ventricle and is composed of two
flaps. Normally the flaps are held tightly closed
during left ventricular contraction (systole)
by the chordae tendineae (small tendon "cords"
that connect the flaps to the muscles of the heart).
In MVP, the flaps enlarge and stretch inward toward
the left atrium, sometimes "snapping"
during systole, and may allow some backflow of
blood into the left atrium (regurgitation).
The
cause of MVP is unknown, but is thought to be
linked to heredity. Primary and secondary forms
of MVP are described below.
- primary MVP
Primary MVP is distinguished by thickening of
one or both valve flaps. Other effects are fibrosis
(scarring) of the flap surface, thinning or
lengthening of the chordae tendineae, and fibrin
deposits on the flaps. The primary form of MVP
is seen frequently in persons with Marfan's
Syndrome or other inherited connective tissue
diseases, but is most often seen in persons
with no other form of heart disease.
- secondary MVP
In secondary MVP, the flaps are not thickened.
The prolapse may be due to ischemic damage (caused
by decreased blood flow as a result of coronary
artery disease) to the papillary muscles attached
to the chordae tendineae or to functional changes
in the myocardium. Secondary MVP may result
from damage to valvular structures during acute
myocardial infarction, rheumatic heart disease,
or hypertrophic cardiomyopathy (occurs when
the muscle mass of the left ventricle of the
heart is larger than normal).
Mitral
valve prolapse may not cause any symptoms. The
following are the most common symptoms of MVP.
However, each individual may experience symptoms
differently. Symptoms may vary depending on the
degree of prolapse present and may include:
- palpitations
Palpitations (sensation of fast or irregular
heart beat) are the most common complaint among
patients with MVP. The palpitations are usually
associated premature ventricular contractions
(the ventricles beat sooner than they should),
but supraventricular rhythms (abnormal rhythms
that begin above the ventricles) have also been
detected. In rare cases, patients may experience
palpitations without observed dysrhythmias (irregular
heart rhythm).
- chest pain
Chest pain associated with MVP is different
from chest pain associated with coronary artery
disease (feels different, has different trigger,
and different period of duration) and is a frequent
complaint. Usually the chest pain is not
like classic angina, but can be recurrent and
incapacitating.
Depending
on the severity of the leak into the left atrium
during systole (mitral regurgitation), the left
atrium and/or left ventricle may become enlarged,
leading to symptoms of heart failure. These
symptoms include weakness, fatigue, and shortness
of breath.
The
symptoms of mitral valve prolapse may resemble
other medical conditions or problems. Always consult
your physician for a diagnosis.
Persons
with MVP often have no symptoms and detection
of a click or murmur may be discovered during
a routine examination.
MVP
may be detected by listening with a stethoscope
revealing a "click" (created by the
stretched flaps snapping against each other during
contraction) and/or a murmur. The murmur is caused
by some of the blood leaking back into the left
atrium. The click or murmur may be the only clinical
sign.
In addition
to a complete medical history and physical examination,
diagnostic procedures for MVP may include any,
or a combination, of the following:
- electrocardiogram
(ECG or EKG) - a test that records
the electrical activity of the heart, shows
abnormal rhythms (arrhythmias or dysrhythmias),
and detects heart muscle damage.
- echocardiogram (Also
called echo.) - a noninvasive test
that uses sound waves to produce a study of
the motion of the heart's chambers and valves.
The echo sound waves create an image on the
monitor as an ultrasound transducer is passed
over the heart. Echocardiography is the most
useful diagnostic test for MVP .
In some
situations where symptoms are more severe, additional
diagnostic procedures may be performed. Additional
procedures may include:
- stress test (Also
called treadmill or exercise ECG.) -
a test that is performed while a patient
walks on a treadmill to monitor the heart during
exercise. Breathing and blood pressure rates
are also monitored.
- cardiac catheterization
- with this procedure, x-rays are taken
after a contrast agent is injected into an artery
to locate the narrowing, occlusions, and other
abnormalities of specific arteries. In addition,
the function of the heart and the valves may
be assessed.
Specific
treatment for mitral valve prolapse will be determined
by your physician based on:
- your overall health
and medical history
- extent of the disease
- your signs and symptoms
- your tolerance for
specific medications, procedures, or therapies
- expectations for the
course of the disease
- your opinion or preference
Treatment
is not usually necessary as MVP is rarely a serious
condition. Regular check-ups with a physician
are advised. Because MVP is the most frequent
cause of mitral valve bacterial endocarditis (an
infection of the lining of the heart), one may
be advised to take antibiotics before dental,
urinary, or bowel procedures, or general surgery,
particularly when mitral regurgitation is present.
Persons
with rhythm disturbances may need to be treated
with beta blockers or other medications to control
tachycardias (fast heart rhythms). In most cases,
limiting stimulants such as caffeine and cigarettes
is all that is needed to control symptoms.
If atrial
fibrillation or severe left atrial enlargement
is present, treatment with an anticoagulant may
be recommended. This can be in the form of
aspirin or warfarin (Coumadin®) therapy.
For
the person with symptoms of dizziness or fainting,
maintaining adequate hydration (fluid volume in
the blood vessels) with liberal salt and fluid
intake is important. Support stockings may
be beneficial.
If severe
mitral regurgitation resulting from a floppy mitral
leaflet, rupture of the chordae tendineae, or
extreme lengthening of the valve should occur,
surgical repair may be indicated.
This
condition is usually harmless and does not shorten
life expectancy. Healthy lifestyle behaviors
and regular exercise are encouraged.
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