heart disease, ischaemicThe 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 ofA 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
hyperlipidaemiasthat 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
beriberiwith 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 pectorisor, 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 pulmonaleis a failure of the
right side of the heart as a consequence
of lung disease.
heart failureInability of the heartto
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 valvedefect (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
drugsare given, and digitalis drugsand
vasodilators, especially ACE inhibitors,
may also be administered. Morphine
and oxygenmay be given as emergency
treatment in acute left-sided failure.
heart imagingTechniques 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 oedemaand engorgement of
the vessels connecting the heart and
lungs are also usually detectable.HEART DISEASE, ISCHAEMIC HEART IMAGING
H