Non-Invasive Tests
Chest X-ray
A conventional X-ray of the chest yields basic information
about the size and shape of the patient’s heart,
blood vessels, and lungs.
Electrocardiography / Electrocardiogram
Electrocardiography is a method of measuring the electrical
impulses in the heart. This is usually done by placing
12 electrodes on the patient’s chest and limbs.
The electrodes are then connected to a machine which records
the rhythm, frequency of beats, and electrical conduction
of the patient’s heart. The test takes about 10
minutes to complete, and the printed result is known as
an electrocardiogram, or “ECG” for short.
It contains information about:
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the patient’s
heart rhythm and heart rate; |
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any previous or on-going heart
attacks; |
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the thickening of the heart
muscle and enlargement of the chambers of the heart,
if any; |
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whether or not blood supply
to the patient’s heart is poor. |
Together, such data provides clues to the likely reasons
for the patient’s cardiac condition as well as the
appropriate course of treatment.
Holter monitoring
A variation on conventional electrocardiography is Holter
monitoring. This is ECG monitoring done over time, usually
in the course of a normal day’s activities. For
this form of electrocardiography, the patient carries
an ECG monitor in a small satchel worn on his body so
that measurements may be taken of any spontaneous periods
of chest pains and/or irregular heart rhythms which he
may experience during the test period.
Exercise Stress Test
Sometimes, an ECG is done while the patient is exercising.
Typically, the patient is asked to run on a treadmill
while wearing the usual ECG electrodes. Recordings are
taken simultaneously at 3-minute intervals, with the speed
and elevation of the treadmill being gradually increased
in the course of the test until the patient either reaches
his target exercise heart rate or develops chest pains
and indicates that he is unable to continue with the test.
An exercise ECG is most helpful for a patient who experiences
chest pains only upon physical exertion, but who otherwise
has normal ECG results when at rest. It allows doctors
to assess the amount of physical activity which such a
patient can undertake comfortably (also known as his “exercise
tolerance”). It also sheds light on how well his
heart responds to the stress arising naturally from exercise.
Echocardiography
Echocardiography is a technique which uses sound waves
(ultrasound) to evaluate the internal structure, movement,
chambers, and valves of the patient’s heart. It
is also useful in the diagnosis of heart attacks and coronary
heart disease. Spectral Doppler echocardiography is a
special form of echocardiography which analyses the speed
and direction of blood flow in the patient’s cardiovascular
system. It helps to highlight any disorders of the heart
valves, coronary muscles, and coronary arteries which
the patient might have.
Computed Tomography (CT) Scan
Also known as a CAT scan, a CT scan provides cross-sectional
images of the patient’s chest, including his heart
and the surrounding blood vessels. It is useful in the
diagnosis of cardiac tumours, aortic disease, as well
as pericardial disease (disease of the pericardium).
Magnetic Resonance Imaging (MRI)
In MRI, powerful magnets are used to produce three-dimensional,
high-resolution images of the patient’s internal
body structures. Such images, which include detailed information
about the heart muscle, are vital in the detection of
damage caused by a heart attack, diseases of the coronary
arteries, and other cardiovascular defects.
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