CARDIOPULMONARY RESUSCITATION
achieved by the patient exercising on a
treadmill or stationary bicycle. Specific
changes
in the
electrical pattern as
exercise levels increase indicate
angina
pectoris
(chest pain due to impaired
blood supply to the heart m uscle).
Cardiac stress testing may also be
used in conjunction with
radionuclide
scanning
in order to identify damaged
areas of heart muscle.
cardiology
The study of the function of the
heart
and the investigation, diagnosis, and
medical treatment of disorders of the
heart and blood vessels, such as
athero-
sclerosis
(fat deposits on the artery walls)
and
hypertension
(high blood pressure).
Some disorders reduce the pumping
efficiency of the heart. They include
arrhythmias (abnormalities in the rate
or rhythm of the heartbeat; see
arrhyth-
mia, cardiac
) ,
coronary artery disease
(in
w hich the blood supply to the heart
muscle is impaired),
cardiomyopathy
(in
w hich the heart muscle itself is abnor-
mal), and
heart valve
disorders.
Some babies are born with structural
defects of the heart and/or the major
blood vessels that emerge from it (see
heart disease, congenital
) .
Diseases of the
lungs and blood vessels can also have
adverse effects on heart function.
Many people w ith heart problems
are treated by their general practition-
ers, but some may be referred to a
cardiologist (a heart specialist). Investi-
gations
may
include
tests
such
as
echocardiography
(viewing the structure
and movement of the heart using ultra-
sound) and detailed interpretation of
ECGs
(electrocardiograms, w hich mea-
sure the electrical activity of the heart).
If coronary artery disease is suspected,
the cardiologist may perform coronary
angiography
(taking X-ray images
of
blood vessels) and possibly widen any
blocked blood vessels (see
angioplasty,
balloon
) .
A cardiologist may, in turn,
refer a patient to a cardiovascular sur-
geon if surgical treatment is required.
cardiomegaly
Enlargement of the
heart
.
This condi-
tion may take the form of
hypertrophy
(thickening) of the heart muscle or of
dilatation (increase in volume) of one
or more of the heart chambers.
CAUSES
Hypertrophy
of
the
heart
muscle
occurs in conditions in w hich the heart
has to work harder than normal to
pump blood. These disorders include
hypertension
(high
blood
pressure),
w hich causes the wall of the left ventri-
cle to thicken;
pulmonary hypertension
(raised blood pressure in the lungs), in
w hich the w all of the right ventricle
thickens; and one type of
cardiomyo-
pathy
(disease of the heart muscle), in
w hich the walls of one or both ventri-
cles may thicken.
Dilation of a heart chamber may
be due to heart valve incompetence
(failure of a valve to close properly
after a contraction). In
aortic insuffi-
ciency
,
failure of the aortic valve to
close completely allows blood to flow
back from the aorta into the left ventri-
cle after each contraction, eventually
enlarging the chamber.
SYMPTOMS
Symptoms of cardiomegaly may not
occur until the heart has enlarged to
the point where it cannot cope with
additional stress
(for example,
as a
result of exercise or infection). The
heart’s
reduced
pum ping
efficiency
leads to
heart failure,
with symptoms of
breathlessness and ankle swelling.
DIAGNOSIS AND TREATMENT
Cardiomegaly is diagnosed by a physi-
cal examination,
chest X-ray
,
and
ECG
(measurement of the electrical activity
of the heart). Treatment is directed at
the underlying cause.
cardiomyopathy
Any disease of the heart muscle that
weakens the force of cardiac contrac-
tions, thereby reducing the efficiency
of blood circulation. Cardiomyopathies
may be the result of infectious, meta-
bolic, nutritional, toxic, autoimmune,
or degenerative disorders. However, in
many cases, the cause is unknown.
TYPES
There are three principal forms of the
condition: hypertrophic,
dilated, and
restrictive cardiomyopathy.
Chest X-ray showing cardiomyopathy
The heart has become greatly enlarged as a result
of the heart-muscle abnormality.
In
hypertrophic
cardiomyopathy, the
heart muscle is abnormally thickened.
This condition is usually inherited.
In dilated cardiomyopathy, w hich is
often of unknown cause,
metabolism
(chemical activity) of the heart muscle
cells is abnormal and the heart’s walls
tend to balloon out under pressure.
Restrictive cardiomyopathy is a con-
dition in w hich the heart walls are
unusually inflexible, so that the heart
cannot fill sufficiently with blood. It is
often caused by scarring of the endo-
cardium (the inner lining of the heart)
or by
amyloidosis
(infiltration of the
muscle with a starchlike substance).
SYMPTOMS AND SIGNS
Symptoms of cardiomyopathy include
fatigue, palpitations, and chest pain.
Palpitations may be due to an abnormal
heart rhythm such as
atrial fibrillation
(rapid, uncoordinated contractions of
the upper chambers of the heart).
The condition may lead to
heart fail-
ure
,
in w hich the pum ping action of
the heart becomes less efficient. Symp-
toms of heart failure include breathing
difficulty and
oedema
(abnormal fluid
accumulation in body tissues).
DIAGNOSIS
A
chest X-ray
may show enlargement of
the
heart,
and
echocardiography
(an
ultrasound technique for imaging the
structure and movement of the heart)
may show thickened heart muscle. A
biopsy
(small tissue sample removed for
microscopic analysis) of heart muscle
may reveal muscle cell abnormalities.
TREATMENT
Symptoms of cardiomyopathy may be
treated with
diuretic drugs
to control
heart failure and
antiarrhythmic drugs
to
correct the abnormal heart rhythm. In
many
cases,
heart
muscle
function
deteriorates, and the only remaining
option is a
heart transplant
.
cardiopulmonary bypass
The procedure by w hich the circulation
of blood around the body is main-
tained w hile the heart is stopped during
heart surgery. A
heart-lung machine
is
used to maintain the supply of oxy-
genated blood to the body tissues.
cardiopulmonary resuscitation
The administration of life-saving mea-
sures to a person who has suffered a
cardiac arrest
(in w hich the heart stops
pum ping blood). A person in cardiac
arrest shows no sign of breathing and
has no detectable pulse or heartbeat.
C
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