Congestive
heart failure (CHF for short) affects 1 to 2 million individuals
in the United States. As the population continues to age, the
problem of CHF is becoming more common. In short, CHF is usually
caused by a heart that just won't pump like it used to.
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How
Your Heart's Chambers and Valves Work
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| Blood
moves through four chambers (two atriums and
two ventricles) in the heart before circulating
through the body (see Figure 1). With each heartbeat,
blood returns from the body through the veins,
enters one of the chambers-the right atrium-and
moves through the valve into the right ventricle
below it. At the same time, blood from the lungs
that is rich in oxygen enters the left atrium
on the other side of the heart. From the left
atrium, the blood passes through a valve into
the left ventricle. |
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| Next,
the right ventricle contracts after getting
blood from the right atrium, sending blood to
the lungs to get oxygen (See Figure 2). At the
same time, the left ventricle contracts after
getting blood from the left atrium. When the
left ventricle contracts, it pumps blood through
the aorta to arteries in all parts of the body. |
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The
heart has four valves. Two prevent blood from
flowing back between the atriums and ventricles.
The other two valves prevent blood from flowing
backward from the arteries and into the ventricles.
Normally, the left ventricle pumps one-half
or more of the blood in it with each beat. With
heart failure, the left ventricle cannot contract
strongly enough, pumping two-fifths or less
of the blood in it with each beat. |
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| Source:
Agency for Healthcare Research and Quality (formerly
the Agency for Health Care Policy and Research). |
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The
heart has a very important role in the body - namely, to cause
blood to circulate throughout the body in order to supply oxygen
and nutrition to the tissues.
If
the heart is damaged or abnormal, it may not be able to effectively
perform its role as the body's "pump." Occasionally, CHF can
occur because of sudden damage to the heart (such as during
a heart attack). Most often, however, CHF is due to chronic
stress that weakens the heart.
What
causes CHF?
The
most common cause of CHF is high blood pressure in conjunction
with clogging and hardening (or "atherosclerosis") of the arteries.
High blood pressure causes the heart to have to pump extra hard
in order to get enough blood circulating.
After
years of having to work against high blood pressure, the heart
muscle starts to get bigger and thicker - just like someone
who lifts heavy weights gets big muscles. With the heart, this
is not a good thing, however.
The
heart can start to get too big for its own good, and this can
lead to poor blood flow and oxygen delivery to the heart. Couple
this with clogging of the arteries that supply the heart and
its easy to understand why the heart ultimately becomes weaker
over time.
Eventually,
the heart is unable to pump enough blood to meet the body's
demands - this is when symptoms begin.
What
are the symptoms?
The
first symptoms of heart failure are generally decreased exercise
tolerance and fatigue. Normally, when we exercise, the heart
pumps harder and faster to meet the increasing oxygen demand
of the muscles.
In
early heart failure, the heart is too weak to increase the blood
flow enough to meet the body's needs when exercise occurs. The
end result is that a person will experience easy fatigue and
some shortness of breath with exercise because of a relative
lack of oxygen.
When
heart failure starts to worsen, the kidneys (the organs that
make urine) do not receive enough blood, and so they start to
make less urine. This is because urine is simply filtered blood
- therefore, less blood flow to the kidneys results in less
urine produced.
The
end result is that the body winds up retaining too much fluid.
This fluid may back up into the lungs, causing worsening shortness
of breath or end up in the legs, causing swelling of the legs.
People
with CHF may notice that they need to sleep with extra pillows
under their head or even in a sitting position. They may wake
up in the middle of the night short of breath or have to get
up several times during the night to urinate. Each of these
symptoms is due to fluid build-up in the body.
| Medications
Used for Congestive Heart Failure |
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Angiotensin-converting
enzyme (ACE) inhibitors
These
drugs prevent the production of a chemical that
causes blood vessels to narrow therefore blood pressure
drops and the heart doesnt have to work as hard.
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Digitalis:
This drug increases the force of the hearts contraction
and slows certain heart rhythms therefore the heart
beats more effectively.
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Diuretics
These drugs decrease the bodys retention of salt
and water, therefore helping to lower blood pressure
and decrease the workload of the heart.
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Hydralazine
This
drug widens blood vessels, easing blood flow.
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Nitrates
These
drugs help relax smooth muscle and widen blood vessels,
therefore lower blood pressure.
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| Reference:
National Institutes of Health |
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How
is it diagnosed?
To
diagnose CHF, the doctor will need to ask you several questions
about your medical history and examine you. Usually blood tests
and a chest x-ray are done, which can also give clues to the
diagnosis.
An
ultrasound test of the heart (much the same as the ultrasound
used to look at a baby inside the mother's womb) can show how
well the heart is pumping and whether or not there are any structural
abnormalities of the heart.
How
is it treated?
Once
the diagnosis of CHF is made, several medicines are available
to treat it. First, the blood pressure will need to be controlled
to avoid further weakening of the heart. Next, a diuretic, or
"fluid" pill is often prescribed to help the body make more
urine and get rid of the body's excess fluid.
Dietary
measures are also very important. Low salt intake is important
to prevent too much fluid build-up, which worsens symptoms.
Many other medications may be prescribed based on the type and
severity of the heart failure.
While
CHF can occasionally be due to heart problems from other causes,
it is usually due to long-standing high blood pressure and/or
clogging of the arteries that supply blood to the heart. It
is a common condition that usually causes fatigue, shortness
of breath and other symptoms.
Fortunately,
good treatments exist for most people with heart failure and
new medications are constantly being developed. Some of these
medications have even been shown to help reverse some of the
heart damage that leads to CHF. Who says you can't teach on
old dog new tricks?
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