HEART DISEASE, ISCHAEMIC
HEART IMAGING
heart disease, ischaemic
The most
common form of heart disease, in which
narrowing or obstruction of the coronary
arteries,
usually
by
atherosclerosis,
results in a reduced blood supply (see
coronary artery disease).
heart, disorders of
A wide range of
disorders can disrupt the heart's action.
In general, genetic factors do not play
a large part in causing heart disorders,
however they do contribute to the
hyperlipidaemias
that predispose a per-
son to
atherosclerosis
and
coronary
artery disease
. Structural abnormalities
in the heart are among the most
common birth defects (see
heart dis-
ease, congenital
).
Infections after birth may result in
endocarditis
or
myocarditis
. Tumours
arising from the heart tissues are rare.
They include noncancerous
myxomas
and cancerous
sarcomas
.
The heart muscle may become thin
and flabby from lack of protein and
calories.
Thiamine
(vitamin B
1
) defi-
ciency, common in alcoholics, causes
beriberi
with congestive
heart failure.
Alcohol poisoning over many years may
cause a type of
cardiomyopathy
.
Obesity
is an important factor in heart disease,
probably through its effect on other risk
factors, such as
hypertension
,
diabetes
,
and
cholesterol
.
The coronary arteries may become
narrowed due to
atherosclerosis
, depriv-
ing areas of heart muscle of oxygen. The
result may be
angina pectoris
or, eventu-
ally, a
myocardial infarction.
Some drugs, such as the anticancer
drug
doxorubicin
,
tricyclic antidepres-
sants
, and even drugs used to treat
heart disease, may disturb the heart-
beat or damage the heart muscle.
Many common and serious heart dis-
orders may be a complication of an
underlying condition, such as cardiomy-
opathy or a congenital defect. Such
disorders include cardiac
arrhythmia
,
some cases of
heart block
, and heart
failure.
Cor pulmonale
is a failure of the
right side of the heart as a consequence
of lung disease.
heart failure
Inability of the
heart
to
cope with its workload of pumping
blood to the lungs and to the rest of the
body. Heart failure can primarily affect
the right or the left side of the heart,
although it most commonly affects both
sides, in which case it is known as con-
gestive, or chronic, heart failure.
Left-sided heart failure may be caused
by
hypertension
,
anaemia
,
hyperthyroid-
ism
, a
heart valve
defect (such as
aortic
stenosis
,
aortic incompetence
, or
mitral
incompetence
), or a congenital heart
defect (see
heart disease, congenital
).
Other causes of left-sided heart failure
include
coronary artery disease
,
myo-
cardial infarction
,
cardiac arrhythmias
,
and
cardiomyopathy
.
The left side of the heart fails to empty
completely with each contraction, or
has difficulty in accepting blood that
has been returned from the lungs. The
retained blood creates a back pressure
that causes the lungs to become con-
gested with blood. This condition leads
to
pulmonary oedema
.
Right-sided heart failure most often
results from
pulmonary hypertension
,
which is itself caused by left-sided fail-
ure or by lung disease (such as chronic
obstructive pulmonary disease (see
pul-
monary disease
,
chronic obstructive
).
Right-sided failure can also be due to a
valve defect, such as
tricuspid incompe-
tence
,
or a congenital heart defect.
There is back pressure in the circulation
from the heart into the venous system,
causing swollen neck veins, enlargement
of the liver, and
oedema
, especially of
the legs and ankles. The intestines may
become congested, causing discomfort.
Immediate treatment consists of bed
rest, with the patient sitting up.
Diuretic
drugs
are given, and
digitalis drugs
and
vasodilators
, especially
ACE inhibitors
,
may also be administered.
Morphine
and
oxygen
may be given as emergency
treatment in acute left-sided failure.
heart imaging
Techniques that pro-
vide images of heart structure. Imaging
is used to detect disease or abnormalities.
A
chest X-ray
, the simplest and most
widely used method of heart imaging,
shows heart size and shape, and the
presence of abnormal
calcification
.
Pul-
monary oedema
and engorgement of
the vessels connecting the heart and
lungs are also usually detectable.
H
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