Heart
Valve Diseases
The
heart consists of four chambers, two atria (upper
chambers) and two ventricles (lower chambers).
There is a valve through which blood passes before
leaving each chamber of the heart. The valves
prevent the backward flow of blood. These valves
are actual flaps that are located on each end
of the two ventricles (lower chambers of the heart).
They act as one-way inlets of blood on one side
of a ventricle and one-way outlets of blood on
the other side of a ventricle. Normal valves
have three flaps, except the mitral valve,
which has two flaps. The four heart valves include
the following:
- tricuspid valve - located
between the right atrium and the right ventricle
- pulmonary valve - located
between the right ventricle and the pulmonary
artery
- mitral valve - located
between the left atrium and the left ventricle
- aortic valve - located
between the left ventricle and the aorta
As the
heart muscle contracts and relaxes, the valves
open and close, letting blood flow into the ventricles
and out to the body at alternate times. The following
is a step-by-step illustration of how the valves
function normally in the left ventricle:
- After the left ventricle
contracts, the aortic valve closes and the mitral
valve opens, to allow blood to flow from the
left atrium into the left ventricle.
- The left atrium contracts
and more blood flows into the left ventricle.
- When the left ventricle
contracts again, the mitral valve closes and
the aortic valve opens, so blood flows into
the aorta and the systemic circulation.
Heart
valves can have one of two malfunctions:
- regurgitation
The valve(s) does not close completely, causing
the blood to flow backward instead of forward
through the valve.
- stenosis
The valve(s) opening becomes narrowed or does
not form properly, inhibiting the flow of blood
out of the ventricle or atria. The heart is
forced to pump blood with increased force in
order to move blood through the stiff (stenotic)
valve(s).
Heart
valves can have both malfunctions at the same
time (regurgitation and stenosis). When heart
valves fail to open and close properly, the implications
for the heart can be serious, possibly hampering
the heart's ability to pump blood adequately
through the body. Heart valve problems are one
cause of heart failure.
Mild
heart valve disease may not cause any symptoms.
The following are the most common symptoms of
heart valve disease. However, each individual
may experience symptoms differently. Symptoms
may vary depending on the type of heart valve
disease present and may include:
- chest pain
- palpitations caused
by irregular heartbeats
- migraine headaches
- fatigue
- dizziness
- low or high blood pressure,
depending on which valve disease is present
- shortness of breath
- abdominal pain due
to an enlarged liver (if there is tricuspid
valve malfunction)
Symptoms
of heart valve disease may resemble other medical
conditions and problems. Always consult your physician
for a diagnosis.
The
causes of heart valve damage vary depending on
the type of disease present, and may include the
following:
- a history of rheumatic
fever (now a rare disease in north America due
to effective antibiotic treatment) - a condition
characterized by painful fever, inflammation,
and swelling of the joints.
- damage resulting from
a heart attack
- damage resulting from
an infection
- changes in the heart
valve structure due to the aging process
- congenital birth defect
- syphilis (now a rare
sexually transmitted disease in North American
due to effective treatment) - a disease characterized
by progressive symptoms if not treated. Symptoms
may include small, painless sores that disappear,
followed by a skin rash, enlarged lymph nodes,
headache, aching bones, appetite loss, fever,
and fatigue.
- myxomatous degeneration
- an inherited connective tissue disorder that
weakens the heart valve tissue.
The
mitral and aortic valves are most often affected
by heart valve disease. Some of the more common
heart valve diseases include:
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Heart Valve Disease
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Symptoms and Causes
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Bicuspid
aortic valve |
This
congenital birth defect is characterized
by an aortic valve that only has two flaps
(a normal aortic valve has three flaps).
If the valve becomes narrowed, it is more
difficult for the blood to flow through,
and often the blood leaks backward. Symptoms
usually do not develop during childhood,
but are often detected during the adult
years. |
|
Ebstein's
anomaly |
When
Ebstein's anomaly is present, there
is a downward displacement of the tricuspid
valve (located between the upper and lower
chambers on the right side of the heart)
into the right bottom chamber of the heart
(or right ventricle). This condition is
usually associated with an atrial septal
defect, an opening between the two upper
chambers of the heart. |
|
Tricuspid
atresia |
When
tricuspid atresia is present, there is no
tricuspid valve, therefore, no blood flows
from the right atrium to the right ventricle.
Tricuspid atresia defect is characterized
by a small right ventricle, a large left
ventricle or only one ventricle, diminished
pulmonary circulation, and cyanosis (insufficient
oxygen in the blood, which can cause the
skin, gums, and lips to be pale or appear
blue or gray in color). An atrial septal
defect is present to allow blood to enter
the circulatory system from the right side. |
|
Mitral
valve prolapse (also known as click-murmur
syndrome, Barlow's syndrome, balloon
mitral valve, or floppy valve syndrome)
|
This
disease is characterized by the bulging
of one or both of the mitral valve flaps
during the contraction of the heart. One
or both of the flaps may not close properly,
allowing the blood to leak backward. This
may result in a mitral regurgitation murmur. |
|
Mitral
valve stenosis |
Often
caused by a past history of rheumatic fever,
this condition is characterized by a narrowing
of the mitral valve opening, increasing
resistance to blood flow from the left atrium
to the left ventricle. |
|
Aortic
valve stenosis |
This
type of valve disease mainly occurs in the
elderly and is characterized by a narrowing
of the aortic valve opening, increasing
resistance to blood flow from the left ventricle
to the aorta. |
|
Pulmonary
stenosis |
This
condition is characterized by a pulmonary
valve that does not open sufficiently, causing
the right ventricle to pump harder and enlarge. |
Heart
valve disease may be suspected if the heart sounds
heard through a stethoscope are abnormal. This
is usually the first step in diagnosing a heart
valve disease. A characteristic heart murmur (abnormal
sounds in the heart due to turbulent blood flow)
can often indicate valve regurgitation. To further
define the type of valve disease and extent of
the valve damage, physicians may use any of the
following diagnostic procedures:
- 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.
- chest x-ray - a diagnostic
test which uses invisible electromagnetic energy
beams to produce images of internal tissues,
bones, and organs onto film. An x-ray can show
enlargement in any area of the heart.
- cardiac catheterization
- this diagnostic procedure involves a tiny,
hollow tube (catheter) being inserted into an
artery leading to the heart in order to image
the heart and blood vessels. This procedure
is helpful in determining the type and extent
of valve blockage.
- transesophageal echo
(TEE) - TEE is a diagnostic test that is used
to measure the sound waves that bounce off the
heart, creating a graphic image of the movement
of the heart structures.
- radionuclide scans
- these scans use radioactive imaging to view
blood flow, internal organ structure, and organ
function.
- magnetic resonance
imaging (MRI) - a diagnostic procedure that
uses a combination of large magnets, radiofrequencies,
and a computer to produce detailed images of
organs and structures within the body.
Heart
valve disease and surgical procedures
A
person with heart valve disease may need to
take antibiotics before undergoing dental or
other surgical procedures that cause bleeding.
Antibiotics are also recommended by physicians
and dentists before routine professional teeth
cleaning and other procedures involving the
gum or soft tissues of the mouth. Bacteria released
during these and other procedures may enter
the bloodstream and lodge in the heart on the
vulnerable, diseased heart valve. The antibiotics
help prevent against a potentially fatal infection
called endocarditis, an infection of the heart's
lining.
In
addition, inform your dentist and other physicians
if you are taking any anticoagulant medication
(to prevent blood clots), because this medication
can cause excessive bleeding during surgery.
Always
inform your dentist and other physician(s) if
you have heart valve disease.
In some
cases, the only treatment for heart valve disease
may be careful medical supervision. However, other
treatment options may include medication, surgery
to repair the valve, or surgery to replace the
valve. Specific treatment will be determined by
your physician based on:
- your age, overall health,
and medical history
- extent of the disease
- the location of the
valve
- your signs and symptoms
- your tolerance for
specific medications, procedures, or therapies
- expectations for the
course of the disease
- your opinion or preference
Treatment
varies, depending on the type of heart valve disease,
and may include one, or a combination of, the
following:
Medication
In some
cases, medication alone is successful in the treatment
of heart valve disease, and may include:
- Medications such as
beta-blockers, digoxin, and calcium channel
blockers reduce symptoms of heart valve disease
by controlling the heart rate and fibrillation.
- Medications to control
blood pressure, such as diuretics (medications
that remove excess water from the body by increasing
urine output) or vasodilators (medications which
relax the blood vessels, decreasing the force
against which the heart must pump).
Surgery
Surgery
may be necessary to repair or replace the malfunctioning
valve(s). Surgery may include:
- Heart valve repair:
In some cases, surgery on the malfunctioning
valve can help alleviate symptoms. Examples
of heart valve repair surgery include cutting
scarred flaps so they open more easily; remodeling
valve tissue that has enlarged; or inserting
prosthetic rings to help narrow a dilated valve.
In many cases, heart valve repair is preferable,
because a person's own tissues are used.
- Heart valve replacement:
When heart valves are severely malformed or
destroyed, they may need to be replaced with
a new mechanism. Replacement valve mechanisms
fall into two categories: tissue (biologic)
valves, which include animal valves and donated
human aortic valves, and mechanical valves,
which can be metal, plastic, or another artificial
mechanism.
Another
treatment option that is less invasive than valve
repair/replacement surgery is balloon valvuloplasty,
a non-surgical procedure in which a special catheter
(hollow tube) is threaded into a blood vessel
in the groin and guided into the heart. The catheter,
which contains a deflated balloon, is inserted
into the narrowed heart valve and the inflated
balloon is stretching the valve open. The balloon
is then removed. This procedure is often used
to treat pulmonary stenosis and, in some cases,
aortic stenosis.
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