PACEMAKER
PAINFUL ARC SYNDROME
pacemaker A small device that supplies
electrical impulses to the
heart
to main-
tain a regular
heartbeat.
A pacemaker is
implanted when the
sinoatrial node
in
the heart malfunctions, or when the pas-
sage of the electrical impulses that
stimulate heart contractions is impaired
(see
heart block; sick sinus syndrome).
Pacemakers can be fixed-rate (which
discharge impulses at a steady rate) or
demand (which discharge only when the
heart rate slows or a beat is missed).
They may be external (used as a tempo-
rary measure) or internal (implanted in
the chest). Some types can increase the
heart rate during exercise or change an
abnormal rhythm into a normal one.
PACEMAKER
Superior
Wire to
vena
Electrical
right
INTERNAL PACEMAKER IN POSITION
paclitaxel An
anticancer drug
that is
used to treat certain types of cancer,
such as ovarian cancer (see
ovary, cancer
of)
and
breast cancer.
The possible side
effects of paclitaxel can include nausea,
vomiting,
anaemia
, and increased sus-
ceptibility to infection.
paediatrics The branch of medicine that
is concerned with the development of
children, and the diagnosis, treatment,
and prevention of childhood diseases.
paedophilia Sexual attraction to chil-
dren. (See also
child abuse; incest.)
Paget's disease A common disorder of
the middle-aged and elderly, in which the
formation of bone is disrupted. Affected
bones become weak, thick, and deform-
ed. Paget's disease, which is also called
osteitis deformans, usually affects the
pelvis, skull, collarbone, vertebrae, and
long bones of the leg. The disorder may
run in families and mostly affects men.
There are often no symptoms, but if
symptoms do occur, the most common
ones are bone pain and deformity, espe-
cially bowing of the legs. Affected bones
are prone to fracture. Skull changes may
lead to leontiasis (distortion of the facial
bones producing a lion-like appearance)
and to damage to the inner ear, some-
times causing deafness,
tinnitus
,
vertigo
,
or headaches.
The disorder is diagnosed by
X-rays
and
blood tests
. Most people do not need
treatment, or only need
analgesic drugs.
In more severe cases, treatment with
drugs such as
calcitonin
may be pre-
scribed or surgery may be needed.
Paget's disease of the nipple A rare
type of
breast cancer
in which a tumour
develops in the
nipple
. The disease
resembles
eczema
and can cause itching
and a burning feeling. A non-healing
sore may develop. Without treatment,
the tumour may spread into the breast.
Diagnosis is made with a
biopsy
.
pain A localized sensation that can range
from mild discomfort to an excruciating
experience. Stimulation of sensory nerve
endings called nociceptors in the skin
leads to pain messages being sent to
the brain. Some nociceptors respond
only to severe stimulation, others to
warning stimuli. Pain receptors are pre-
sent in other structures, such as blood
vessels and tendons. Pain that may be
felt at a point some distance from the
cause is known as
referred pain.
Treatment for pain may include drugs,
electrical stimulation (
TENS
), surgery,
or therapies such as
acupuncture
. (See
also
pain relief
,
endorphins
.)
painful arc syndrome A condition in
which pain occurs when the arm is raised
between 45 and 160 degrees from the
side. The usual cause is an inflamed
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