What is an
ECG?
ECG
(electrocardiogram) is a test that
measures the electrical activity of the
heart. The heart is a muscular organ
that beats in rhythm to pump the blood
through the body.
The signals that make the heart's muscle
fibres contract come from the sinoatrial
node, which is the natural pacemaker of
the heart.
In an ECG test, the electrical impulses
made while the heart is beating are
recorded and usually shown on a piece of
paper. This is known as an
electrocardiogram, and records any
problems with the heart's rhythm, and
the conduction of the heart beat through
the heart which may be affected by
underlying heart disease.
What is the resting ECG used for?
The
information obtained from an
electrocardiogram can be used to
discover different types of heart
disease. It may be useful for seeing how
well the patient is responding to
treatment.
- It is
a good idea to have an ECG in the
case of symptoms such as dyspnoea
(difficulty in breathing), chest
pain (angina), fainting,
palpitations or when someone can
feel that their own heart beat is
abnormal.
- The
test can show evidence of disease in
the coronary arteries.
Unfortunately, in many people who
have significant narrowing of the
arteries supplying the heart muscle,
the ECG recording made at rest is
often normal. Therefore, if a
significant narrowing is suspected,
an ECG recording is often made when
the patient is exercising (an
exercise stress test) as this is
more likely to reveal the problem.
- An ECG
can be used to assess if the patient
has had a heart attack or evidence
of a previous heart attack.
- An ECG
can be used to monitor the effect of
medicines used for coronary artery
disease.
- An ECG
reveals rhythm problems such as the
cause of a slow or fast heart beat.
- To
demonstrate thickening of a heart
muscle (left ventricular
hypertrophy), for example due to
long-standing high blood pressure.
- To see
if there are too few minerals in the
blood.
An ECG may
appear normal even in the presence of
significant heart disease. Thus, for a
full assessment of the heart, other
tests may be needed.
How
is an ECG performed?
It
depends on what is being measured.
Usually, an ECG is taken while the
patient is resting, but if there is
concern that a patient's symptoms may be
caused by coronary artery disease the
test is done while the patient is on an
exercise bike or treadmill.
It may also be used to assess the
success of drug treatment or coronary
revascularisation such as coronary
intervention or bypass surgery.
It may be necessary to supplement an ECG
with additional tests, such as a
radioisotope perfusion scan, which uses
low-dosage radioactive dye to show which
areas of the heart muscle receive the
best and worst blood supply, or
angiography (X-ray examination of
arteries), to determine the extent of
the illness and the cause of symptoms.
How
is an ECG performed?
- Up to
12 self-adhesive electrodes will be
attached to select locations of the
skin on the arms, legs and chest.
Areas such as the chest where the
electrodes will be placed may need
to be shaved. First, the skin is
cleaned. The test is completely
painless and takes less than a
minute to perform once the leads are
in position. After the test, the
electrodes are removed.
- The
doctor will review the paper
print-out of the ECG.
Is an ECG
dangerous?
- When
the patient is at rest it is
completely harmless.
- If an
exercise test is performed, the
patient may get chest pains that
will resolve after the exercise is
stopped. This examination must be
supervised by a medical doctor in
addition to the ECG technicians. If
necessary, the test will be
discontinued at an appropriate time
such as in the case of significant
chest pain, changes on the ECG, a
drop in blood pressure or simply
when the patient achieves their
target heart rate.
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For more Consult at
aerodoctor@pilots-medical.com
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