Mitral Valve Defects
MITRAL VALVE PROLAPSE
The most common heart valve
abnormality is called mitral valve prolapse
(MVP), which affects mostly women between the
ages of 20 and 40. It can go undetected for
years, as symptoms usually do not occur until
adolescence or even adulthood. It is a condition
of the mitral valve, a two-flapped heart valve
between the left atrium and left ventricle. In
MVP, one or both of the valve flaps are too
large, and the mitral valve does not close
evenly with each heartbeat. Because of this
imperfect closing, the valve itself slightly
balloons back into the left atrium, sometimes
causing what is known as a "click". With the
flap there may sometimes be a slight backward
leaking of blood (regurgitation) as well,
resulting in a heart murmur.
It seems that MVP is an
inherited disorder, although the exact genes are
not known. If proper precautions are taken it
will not affect life expectancy, and generally
has no impact on normal activities.
What are the symptoms?
Generally, a stressful situation
(childbirth, change in job situation or marital
status, viral illness) brings on symptoms that
ordinarily would not be present. Some 60% of
those with MVP never show symptoms. Some
symptoms include:
-
Irregular heartbeat or
palpitations, particularly when lying on the
left side
-
Non-specific sharp or dull
chest pain lasting from a few seconds to
several hours, occurring at rest rather than
during exertion
-
Panic attack, a sudden
feeling of anxiety or doom for no apparent
reason
-
Fatigue and weakness, even
after slight exertion; sometimes
misdiagnosed as Chronic Fatigue Syndrome or
depression
-
Tachycardia, increased
heartbeats often after exertion
-
Migraine headaches,
resulting from abnormal nervous system
control of blood flow
The condition can be detected
during a routine check-up with a simple
stethoscope. After the ventricle begins to
contract, a clicking sound can be heard, the
sound of the abnormal valve fighting the
pressure of the left ventricle. The diagnosis
can be confirmed with a cardiac echo or
echocardiogram, which can also determine the
level of severity of the prolapse and the degree
of regurgitation. Most patients can be monitored
simply, with a follow-up checkup every few
years.
Common risks and problems
associated with MVP
Many MVP patients never
experience any symptoms. However, rare
complications include chest pain and irregular
heart beat, both of which can be treated with
medication, usually a beta-blocker. Another rare
complication involves formation of blood clots
on the valve, making an MVP patient vulnerable
to strokes; this problem requires treatment with
medication.
The most common and serious
MVP-related problem, endocarditis, involves
bacterial infection of the mitral valve.
Although it can be fatal if left untreated,
endocarditis can be easily prevented. MVP
patients are most commonly vulnerable to
introduction of bacteria into the bloodstream
when they are undergoing certain medical
procedures, particularly dental work or minor
surgery. To avoid this, patients should inform
their doctor or dentist that they have MVP, and
be given preventative treatment before the
procedure.
When is surgery recommended?
Although most MVP patients do
very well with treatments and preventive
measures, there is sometimes need for heart
surgery to either repair or replace the mitral
valve. This occurs only among patients who
experience severe mitral regurgitation, which
can result in progressive heart enlargement, and
ultimately, heart failure. Surgeons are more
likely to perform corrective surgery rather than
replace the valve with an artificial one, mainly
because the introduction of an artificial valve
requires lifelong use of blood thinners to
prevent clotting.
MITRAL STENOSIS
Mitral Stenosis is a heart valve
disorder characterized by narrowing or
obstruction of the mitral valve, which prevents
the valve from opening properly. Also known as
Mitral valve obstruction, it affects about 2 out
of 10,000 people. Symptoms usually develop
between the ages of 20 and 50.
Causes & Risk Factors
Mitral Stenosis most commonly
occurs in people who have had rheumatic fever
but can be caused by any disorder that causes
narrowing of the mitral valve. Congenital mitral
stenosis alone is rare. It more commonly occurs
with complex groups of cardiac abnormalities.
Narrowing of the mitral valve
obstructs blood flow from the left atrium to the
left ventricle. This can reduce the amount of
blood that flows forward to the body. The atrium
enlarges as pressure builds up in it, and blood
may backflow into the lungs resulting in fluid
in the lung tissue.
Symptoms may begin with an
episode of atrial fibrillation, or may be
triggered by pregnancy or other stress on the
body such as respiratory infection, stroke,
endocarditis and other cardiac disorders.
Prevention
Mitral stenosis cannot be
prevented but complications can be. As with
mitral valve prolapse, advise your physician or
dentist of any history of heart valve disease
before receiving treatment to prevent a
bacterial infection.
Symptoms
There are often no symptoms, or
symptoms may appear or worsen with exercise or
increase in heart rate. Symptoms include:
-
difficulty breathing after
exercise or when lying flat, also awakening
at night with difficulty breathing
-
cough (may have blood in the
sputum)
-
fatigue, tired easily
-
frequent respiratory
infections such as bronchitis
-
chest discomfort
-
tight, crushing,
pressure, squeezing, constricting
-
radiates to the arm,
neck, jaw, or other areas
-
increases with activity,
decreases with rest
-
sensation of feeling the
heart beat
-
swelling of feet or ankles
Signs and tests
A stethoscope examination
reveals a distinctive murmur, snap, or other
abnormal sounds. This means a rumbling sound is
heard over the point of the heart during the
resting phase of the heartbeat, and it gets more
pronounced just before the heart contraction
begins. Examination may also reveal irregular
heartbeat or lung congestion. Blood pressure is
usually normal. There may be vibration or a
tapping on palpation over the heart making it
difficult to distinguish from a heart tumor.
Narrowing or obstruction of the
valve, or enlargement of the atrium may show on
an echocardiogram, Doppler ultrasound, chest
X-ray, ECG or coronary angiography.
Treatment
No treatment may be necessary if
symptoms are absent or mild. Hospitalization may
be required for diagnosis and for treatment of
more severe symptoms. Medications include
diuretics, digoxin, or antiarrhythmics.
Anticoagulants may be used to prevent blood
clots. Heart valve surgery or replacement of the
valve may be necessary. Balloon valvuloplasty
may be considered instead of surgery.
Expectations
The disorder may be mild or
without symptoms. It may be more severe and
eventually disabling. Complications may be
severe or life threatening. Mitral stenosis is
usually controllable with treatment, and
improved with surgery.
Complications
-
enlargement of the atrium
-
incomplete atrial emptying
-
heart failure
-
pulmonary edema
-
atrial fibrillation
-
stroke
-
emboli to the intestines,
lungs, or other areas
MITRAL REGURGITATION
Mitral Regurgitation is a
disorder in which the mitral heart valve does
not close properly, causing blood to leak into
the left atrium when the left ventricle
contracts. Mitral regurgitation affects
approximately 5 out of 10,000 people.
Causes and risk factors
Regurgitation is caused by
disorders that weaken or damages the valve.
Inadequate closure of the mitral valve causes
blood to backflow to the left atrium decreasing
the blood flow to the rest of the body causing
the heart to pump harder to try to compensate
for the decreased blood flow. It may also be the
result of dysfunction or injury to the valve
following MI or infective endocarditis, which
may result in rupture of the valve, papillary
muscle, or chordae tendineae (the structures
that anchor the valve cusps). Such a rupture
results in the valve leaflet protruding into the
atrium, leaving an opening for the backflow of
blood.
Risk factors include an
individual or family history of the above
disorders.
Prevention
Prompt treatment of causative
disorders reduces the risk of mitral
regurgitation. As with mitral stenosis and
mitral valve prolapse, you should advise your
physician or dentist of any history of heart
valve disease before receiving treatment to
prevent a bacterial infection.
Symptoms
There may be an abrupt onset of
symptoms.
Signs and tests
Palpation may show a vibration
over the heart. A stethoscope may reveal a
distinctive murmur in the heart. If fluid backs
up into the lungs, there may be signs of
congestion of the pulmonary (lung) veins. Blood
pressure is usually normal. Billowing of the
mitral valve and/or regurgitation of blood may
show on an echocardiogram or a coronary
angiography.
A chest X-ray may also show
fluid in the lungs or prominent pulmonary veins.
Swan-Ganz left heart catheterization pressure
readings will record a marked elevation of left
atrial pressure. An ECG usually shows a normal
sinus rhythm, but may show arrhythmias such as
atrial fibrillation. Other tests may include a
chest MRI scan, radionucleotide scans, or a CT
scan of the chest.
Treatment
Hospitalization may be required
for diagnosis and treatment of severe symptoms.
Emergency surgery is often necessary if acute
regurgitation is a result of endocarditis, MI,
or ruptured cordae.
Antibiotics may be prescribed if
there is a bacterial infection. Antiarrhythmics
may be needed to control irregular rhythms.
Vasodilators reduce the workload of the heart.
Digitalis may be used to strengthen heartbeat,
and diuretics to remove excess fluid such as
fluid in the lungs. Anticoagulants or
antiplatelet medications may be used to prevent
clot formation if atrial fibrillation is
present. When blood pressure cannot be
maintained, in emergency situations, the
intra-aortic balloon pump (IABP) reduces
backflow by lowering resistance in the aorta.
Expectations
The outcome varies and depends
on the severity of the acute regurgitation. It
can sometimes be controlled with medications,
but surgery is often necessary as it may become
a chronic condition.
Complications
