What are heart valves?
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
How do the heart valves function?
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.
What is heart valve disease?
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.
What are the symptoms of heart valve disease?
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.
What causes heart valve damage?
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:
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.
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.
How is heart valve disease diagnosed?
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.
Treatment for 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 stretches the
valve open. The balloon is then removed. This procedure
is often used to treat pulmonary stenosis and, in some
cases, aortic stenosis.
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.
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