achieved by the patient exercising on a
treadmill or stationary bicycle. Specific
electrical pattern as
exercise levels increase indicate
(chest pain due to impaired
blood supply to the heart m uscle).
Cardiac stress testing may also be
used in conjunction with
in order to identify damaged
areas of heart muscle.
The study of the function of the
and the investigation, diagnosis, and
medical treatment of disorders of the
heart and blood vessels, such as
(fat deposits on the artery walls)
(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
coronary artery disease
w hich the blood supply to the heart
muscle is impaired),
w hich the heart muscle itself is abnor-
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-
(viewing the structure
and movement of the heart using ultra-
sound) and detailed interpretation of
(electrocardiograms, w hich mea-
sure the electrical activity of the heart).
If coronary artery disease is suspected,
the cardiologist may perform coronary
(taking X-ray images
blood vessels) and possibly widen any
blocked blood vessels (see
A cardiologist may, in turn,
refer a patient to a cardiovascular sur-
geon if surgical treatment is required.
Enlargement of the
tion may take the form of
(thickening) of the heart muscle or of
dilatation (increase in volume) of one
or more of the heart chambers.
occurs in conditions in w hich the heart
has to work harder than normal to
pump blood. These disorders include
w hich causes the wall of the left ventri-
cle to thicken;
(raised blood pressure in the lungs), in
w hich the w all of the right ventricle
thickens; and one type of
(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
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 of cardiomegaly may not
occur until the heart has enlarged to
the point where it cannot cope with
result of exercise or infection). The
with symptoms of
breathlessness and ankle swelling.
DIAGNOSIS AND TREATMENT
Cardiomegaly is diagnosed by a physi-
(measurement of the electrical activity
of the heart). Treatment is directed at
the underlying cause.
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.
There are three principal forms of the
Chest X-ray showing cardiomyopathy
The heart has become greatly enlarged as a result
of the heart-muscle abnormality.
heart muscle is abnormally thickened.
This condition is usually inherited.
In dilated cardiomyopathy, w hich is
often of unknown cause,
(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)
(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
(rapid, uncoordinated contractions of
the upper chambers of the heart).
The condition may lead to
in w hich the pum ping action of
the heart becomes less efficient. Symp-
toms of heart failure include breathing
accumulation in body tissues).
may show enlargement of
ultrasound technique for imaging the
structure and movement of the heart)
may show thickened heart muscle. A
(small tissue sample removed for
microscopic analysis) of heart muscle
may reveal muscle cell abnormalities.
Symptoms of cardiomyopathy may be
heart failure and
correct the abnormal heart rhythm. In
deteriorates, and the only remaining
option is a
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
used to maintain the supply of oxy-
genated blood to the body tissues.
The administration of life-saving mea-
sures to a person who has suffered a
(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.