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Topic
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Description
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Echocardiography
in Assessing
the Outcome of Bronchopulmonary
Dysplasia of the Newborn
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Cardiac
catheterization of infants with
bron-chopulmonary dysplasia has depicted right ventricular
hypertrophy and pulmonary
hypertension in most of
the survivors. This study was
planned to find out
whether
continuous
echocardiographic
assessments of the
pulmonary vascular bed could help to
determine short-term prognosis of bronchopulmonary dysplasia
and to evaluate myocardial function of the survivors. Ten preterm
infants were observed for this study. They were classified
according to four radiologic stages. A total of 50
echocardiographs
were recorded so serial
measurements of the right systolic
time intervals could be carried out.
Cardiac catheterization of infants
with bron-chopulmonary dysplasia has displayed right
ventricular hypertrophy and
pulmonary hypertension. This study
was planned to find out
if serial
echocardiography
assessments
of the pulmonary vascular
bed could help to establish
short-term prognosis of
bronchopulmonary dysplasia and to
evaluate myocardial function of the
survivors. Ten
preterm infants were again included
in this study. They were
classified according to four
radiologic stages. A
total of 50
echocardiographs
were recorded for the purpose of
serial measurements of
the right systolic time intervals.
The
lungs
as
seen on chest x-rays of this patient
remained unaltered (moderate stage IV) during six months,
while the
echocardiograph
showed a rapid increase
in right pre-ejection period to
right ejection time
ratio. This infant now has cor
pulmonale.
Myocardial
function evaluated on the last
echocardiograph of the four infants who were
considered cured was within the
permissive limits. Thus
it can be concluded that indirect
assessment of pulmonary pressure by
echocardiography can
be used for clinical evaluation and ultimate prognosis of
bronchopulmonary dysplasia and
should be part of the
follow-up evaluation of infants
suffering from this
health condition.
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Stress echocardiography |
Cardiologist Dr Maria Prokudina, of the Almazof Federal Centre of Heart, Blood and Endocrinology, when invited by Professor John Elefteriades MD, head of Department of Cardiothoracic Surgery at Yale-New Haven Hospital (University School of Medicine) to lecture about Stress Echocardiography in Clinical Practice, exclaimed her surprise as she knew American cardiologists widely applied this method practically and so she did not have anything new to tell them. But Dr Elefteriades, a world renowned surgeon in this field, insisted that she had unique personal insights and experience and they were all waiting for her.
The Russian doctor then explained that it was about the way of working. Ischaemic disease is the main cause of the high morbidity rate (25,300:100,000). About 35 million Russians suffer from cardiovascular disease and about a million die each year. The huge problem for us is inadequate diagnostics. It’s well-known that more than 50% of patients do not have any ECG changes when resting. But ECG and exercise ECG testing are traditional methods of diagnoses in Russia, although these tests are able to detect ischaemia in the later stages of the ischaemic cascade, contributing acknowledged limitation in diagnostic accuracy (decreased sensitivity).
For this reason, Russian specialists have been using the latest IT methods for the last few years, Dr Prokudina pointed out. She continued that stress echocardiography is a non-invasive diagnostic method that combines a baseline echocardiogram with a peak/post exercise echocardiogram to detect and assess coronary artery disease. We choose the treadmill or bicycle test as a stress-agent, but American colleagues pick the pharmacologic test with dobutamine or dipyridamole. If a patient with coronary artery disease (CAD) exercises, ischemia will be induced in the region subtended by a critically stenosed coronary artery. This will be shown as an abnormality of cardiac function, which can be found out by echocardiographic imaging. With exercise, there is usually an increase in left ventricular contractility. In the presence of CAD, stress induced myocardial ischaemia results in a decrease/cessation of contractility in the myocardial region supplied by the stenosed vessel. The ischaemic wall(s) appears hypokinetic, akinetic or diskinetic. The key to success is having the patient reach 90% of the age-predicted maximum heart rate for at least one minute and double outcome greater than 25,000.
The patient's symptoms during exercise (e.g. workload performed, heart rate, blood pressure response) should be noted.
Exercise electrocardiography information (e.g. EKG changes, presence of arrhythmias) should be evaluated.
Overall and segmental left ventricular systolic function pre- and post exercise) should also be evaluated.
A wall motion score should be assigned to each wall segment visualised, and a wall motion score index must be calculated.
Dr Prokudina continued that many physicians are afraid to give patients stress-echo tests thinking it may be dangerous for them, especially after having had a heart attack. But this method is not dangerous – the patient is under the control of the specialist and equipment every moment. There were more than 5,000 heart attacks in St. Petersburg last year and everyone understands that it is possible to avoid heart disaster if the right diagnostics are used.
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Stress
Echocardiography |
Echocardiography, stress: A
supplement to the routine exercise
cardiac stress test. During stress
echocardiography, the sound waves of
ultrasound are used to produce
images of the heart at rest and at
the peak of exercise.
In a heart with normal blood supply,
all segments of the left ventricle
(the major pumping chamber of the
heart) exhibit enhanced contractions
of the heart muscle during peak
exercise. Conversely, in the setting
of coronary artery disease (CAD), if
a segment of the left ventricle does
not receive optimal blood flow
during exercise, that segment will
demonstrate reduced contractions of
heart muscle relative to the rest of
the heart on the exercise
echocardiogram.
Stress echocardiography is very
useful in enhancing the
interpretation of the routine
exercise cardiac stress test (ECST).
It can be used to exclude
significant CAD in patients who are
suspected of having a
"false-positive" ECST, a falsely
abnormally result on the screening
ECST test. |
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Reason
for performing the test |
A
stress echocardiogram is usually
done to find out if you might have
decreased blood flow to your heart
(coronary artery disease, or CAD).
Coronary artery disease is caused by
the buildup of plaque on the inside
of the coronary arteries, the blood
vessels that supply oxygen-rich
blood to the heart muscle. Plaque is
made up of excess cholesterol,
calcium, and other substances that
float in blood and, over time, build
up on the inside walls of the
coronary arteries and other
arteries.
This process of plaque buildup is
called hardening of the arteries, or
atherosclerosis. The plaque deposits
decrease the space through which
blood can flow. Poor blood flow can
"starve" the heart muscle and lead
to chest pain. A heart attack
results when blood flow is
completely blocked, usually by a
blood clot forming over a plaque
that has broken open (ruptured).
Coronary artery disease is treated
with lifestyle changes, such as
increasing exercise, eating a
heart-healthy diet, and stopping
smoking. Coronary artery disease
also is treated with medications to
help reduce high cholesterol,
control high blood pressure, and
manage other risk factors. |
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How is
a Stress Echo performed |
An
Echo Stress can be obtained in a
physician's office or in the
hospital. Imaging tests are
generally obtained when a physician
wishes to confirm or rule out the
presence of coronary artery disease.
A Stress Echo is also performed in
patients who have disease involving
the heart muscle or valve, or if a
patient is having inappropriate
shortness of breath and a cardiac
cause is suspected. The patient is
brought to the Echo laboratory where
a "resting" study is performed. This
provides a baseline examination and
demonstrates the size and function
of various chambers of the heart.
Particular attention is paid to the
movement of all walls of the left
ventricle (LV). Similar to a regular
echo test, sticky patches or
electrodes are attached to the chest
and shoulders and connected to
electrodes or wires to record the
electrocardiogram (EKG or ECG). The
EKG helps in the timing of various
cardiac events (filling and emptying
of chambers). A colorless gel is
then applied to the chest and the
echo transducer (as described in the
Echocardiogram section) is placed on
top of it. The echo technologist
then makes recordings from different
parts of the chest to obtain several
views of the heart. You may be asked
to move form your back and to the
left side. Instructions may also be
given for you to breathe slowly or
to hold your breath. This helps to
obtain higher quality pictures. The
images are constantly viewed on the
monitor. It is also recorded on
photographic paper, on videotape and
on a computer disk. 12 leads of the
EKG are recorded on paper and the
blood pressure is taken. Exercise is
then initiated using a treadmill
(most common) or a stationary
bicycle. In patients who are unable
to complete a high level of exercise
because of physical limitations,
stress to the heart is provided by
pharmaceutical or chemical
stimulation of the heart. Stress
Echo is made up of three parts: A
resting Echo study, Stress test, and
a repeat Echo while the heart is
still beating fast. Exercise stress
testing usually employs the "Bruce"
or a similar protocol, as described
in the Regular Stress Test section.
Exercise is started at a slower
"warm-up" speed. The speed of the
treadmill and it's slope or
inclination is increased every 3
minutes. The treadmill is abruptly
stopped when the patient exceeds 85%
of the target rate (based upon the
patient's age). Exercise may be
stopped earlier if the patient
develops alarming symptoms (chest
discomfort, marked shortness of
breath, weakness, dizziness, etc.),
if there is dangerous elevation or
drop in the blood pressure,
significant EKG changes or a
potentially dangerous irregular
heart rhythm. Please remember that
you have a physician in attendance
(although an experienced assistant
may perform the test if the
physician is tied up with an
emergency). The above problems are
uncommon and you are far safer if
they occur in the presence of an
experienced medical team rather than
having them happen while you are
exercising in a spa, jogging, or
running up a flight of office
stairs.
EKG recordings are made during every
minute of exercise and then again
after exercise is stopped. The blood
pressure is recorded at three minute
intervals during exercise and then
again at rest.
Immediately after stopping the
treadmill, the patient moves
directly to the examination table
and lays on the left side. The Echo
examination is immediately repeated.
Images are stored and then played
back by the computer. A video clip
of multiple views of the resting and
exercise study are compared
side-by-side. They are analyzed by
the physician. Normally, one expects
an increased EF or ejection fraction
(a measure of how well the heart is
pumping). Also, the LV walls do not
show any exercise-induced abnormal
movement. In contrast, a drop in EF
and/or a new wall motion abnormality
is an indicator of disease. |
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Preparing for the Echo Stress Test |
The
following recommendations are
"generic" for all types of cardiac
stress tests:
Do not eat or drink for three hours
prior to the procedure. This reduces
the likelihood of nausea that may
accompany strenuous exercise after a
heavy meal. Diabetics, particularly
those who use insulin, will need
special instructions from the
physician's office.
Specific heart medicines may need to
be stopped one or two days prior to
the test. Such instructions are
generally provided when the test is
scheduled.
Wear comfortable clothing and shoes
that are suitable for exercise.
An explanation of the test is
provided and the patient is asked to
sign a consent form. |
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How
safe is a Stress Echo test |
There
are no known adverse effects from
the ultrasound used during Echo
imaging. The risk of the stress
portion of the test is rare and
similar to what you would expect
from any strenuous form of exercise
(jogging in your neighborhood,
running up a flight of stairs,
etc.). As noted earlier, experienced
medical staff is in attendance to
manage the rare complications like
sustained abnormal heart rhythm,
unrelieved chest pain or even a
heart attack. These problems could
potentially have occurred if the
same patient performed an equivalent
level of exercise at home or on a
jogging track. |
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What
is the reliability of Stress Echo |
If a
patient is able to achieve the
target heart rate and if the ECHO
images are of good technical
quality, a Stress Echo is capable of
diagnosing important disease in more
than 85% of patients with coronary
artery disease. Also, it can exclude
important disease in more than 90%
of cases when the test is absolutely
normal. |
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How
quickly will I get the results and
what will it mean |
The
physician conducting the test will
be able to give you the preliminary
results before you leave the Stress
Echo laboratory. However, the
official result may take a few days
to complete. The results of the test
may help confirm or rule out a
diagnosis of heart disease. In
patients with known coronary artery
disease (prior heart attack, known
coronary blockages, previous
treatment with angioplasty, stents
or bypass surgery, etc.), the study
will help confirm that the patient
is in a stable state, or that a new
blockage is developing. The results
may influence your physician's
decision to change your treatment or
recommend additional testing such as
cardiac catheterization |