Description

Stress Electrocardiography

Ieforluelectrocardiography The exertion test is performed during standard physical activity that is progressively
increased and strictly controlled. Its purpose is to determine whether the
patient has coronary insufficiency and to determine the severity of the disease
through some special criteria.
During physical exertion, the patient’s oxygen consumption increases. The
increased oxygen requirement is met by increased heart rate and
therefore increased coronary blood flow.
Maximum oxygen consumption in each person is determined by maximum coronary
blood flow; this is proportional to the theoretical upper limit of heart rate. The
theoretical maximum heart rate is represented by the formula: 220 – patient’s
age (standard deviation ± 12). Accordingly, the heart of a 50-year-old
patient would theoretically beat at most 170 times per minute. This is the
number of beats to be reached gradually during the effort test. 80 percent
of this is considered as “under-maximum” (close to maximum).
If the maximum speed is reached without any disturbance in the
electrocardiography (ECG) or symptoms such as pain or shortness of breath, it is
understood that the coronary vessels are healthy.
On the other hand, if there is a blockage in the coronary arteries and this
blockage prevents the blood flow required by the physical effort, disorders due
to insufficient blood supply to the heart and chest pains in the form of
angina appear on the EKG . The heart rate at which these
symptoms occur is called the “ischemia threshold”, that is, the
regional anemia threshold. There
are other important criteria used to determine
coronary artery disease . These
are arterial pressure ( blood
pressure can become very high during exertion ), duration of
exertion, and the level of power or load required to reach critical beat
frequency. In this case, the examination is only the ECG.Since it is not
limited to the data, it is more correct to call the procedure an exercise test
instead of an exercise ECG.
Regional anemia (ischemia) and associated angina pain that occurs during
physical activity are caused by the deterioration of the balance between the
oxygen requirement of the heart muscle and the oxygen input. This is due
to narrowing of the coronary arteries, which prevents increased blood flow.
Chest pains due to physical exertion do not show electrocardiographic symptoms
at the normal time unless an ECG is taken during the crisis. In contrast,
typical ECG ischemia almost
always pain after onset of symptoms embodiment
Stress electrocardiography does not require much equipment, but the quality of
the devices used is very important for reliable results of the test.
The following devices are used during the test:
• Ergometer bicycle. It is a bicycle with electromagnetic brakes adjusted
to provide an accurate measurement of the effort required to pedal; It
stays in place like a gym bike. A walking belt can also be used instead of
such a bicycle; The patient walks or runs on this band, whose movement speed and slope can be
adjusted. The Master test, which is based on two steps constantly
ascending and descending, is no longer practiced.
• Electrocardiograph device. It records continuously while powering up.
• Mercury manometer. It is used to measure arterial blood pressure.
• Electrodes. One end is glued to the body; The other end connected
to the EKG allows recording.
• Defibrillator, oxygen tube and necessary drugs against any function and
severe rhythm disturbances that may occur in the heart during the test. It
is used in emergencies.
APPLICATION CONDITIONS The
decision to apply for an exercise test can only be made after careful clinical
examination and evaluation of the ECG taken at rest. All these
examinations should be performed by the physician responsible for the
test. Sometimes the physician may conclude that the test may be dangerous
by detecting new clinical signs or ECG changes, even in the patient referred to
with very appropriate documentation.
After taking the ECG at rest and measuring the blood pressure, the patient
starts the test by consuming 30 watts of power for three minutes. The
power consumed is increased by 30 watts every three minutes, up to 210-270
watts. The three-minute period is the time required for the organism to
adapt to the new force. At the end of each three-minute period, a long ECG
recording is taken without interrupting the patient’s effort. On this
recording, it is checked whether there are signs of ischemia, whether the heart
rhythm accelerates, and whether the blood pressure rises. If any symptoms
suggesting ischemia or requiring the test to be stopped appear, the next level
of exertion is not passed.
Maximum power is the power that enables the heart rate to reach the theoretical
upper limit and varies according to the age, weight and sex of the patient.
If the heartbeat has not accelerated to the theoretical upper limit, the test
should be stopped if the following symptoms occur:
• Significant shortness of breath or muscle weakness;
• low or insufficient blood pressure;
• significant rhythm disturbances;
• angina-type chest pains (even if there is no abnormality on the electrocardiogram).
TEST RESULTS Interpreting the test result as “normal” indicates normal coronary blood flow
and is a difficult decision to make. However, in some cases, the physician
can safely make this decision. Negative response An
effort test gives a negative (negative) result in the following situations:
• The patient’s lying chest pain is not due to exertion and no change in the
ECG is revealed during exertion.
• If there are so-called “atypical” disturbances in the resting ECG, but these
have disappeared during exertion and no symptoms have appeared.
• If various atypical symptoms occur only during exertion and for a certain
period of time (for example, pain occurs when exertion begins and disappears
with greater exertion, while the ECG remains normal and blood pressure is not
abnormal).
Caution: A negative effort test result is not an automatic indication of
the absence of coronary insufficiency, especially in men over 40
years of age who show typical angina pectoris symptoms. “Abnormal” result
A test result may be considered “abnormal” if:
• Heart rate increases with exertion, but blood pressure does not rise as much
as necessary. This is the coronary arteryit may be caused by
left ventricular failure suggestive of stenosis. If there is chest pain
during physical activity or rest, the absence of blood pressure may be due to
droopy mitral valve or aortic valve stenosis. Methods such as
echocardiography should be used to examine these possibilities in detail.
• If the patient had to stop the test because of chest pain, even though the
EGK was normal. In this case, the test result is positive, and the only
symptom that leads to the conclusion of coronary insufficiency is chest pain,
which occurs during exertion and disappears when the test is stopped.
• A negative result of the test does not indicate that there is no true angina
pectoris. Sometimes there is a typical angina, but the symptoms are not
seen during the exercise test and do not cause disturbances in the EKG.
Positive response Although the resting ECG is
normal, the ECG taken during the exercise test shows disturbances indicating
ischemia. Sometimes these disorders are accompanied by chest pain .
DISEASE WEIGHT the EVALUATION CRITERIA
evaluating the test results, there are some criteria that allows the physician
to decide on the weight of the coronary insufficiency.
• If the disorder occurs close to the theoretical maximum heart rate and is
limited to a very small number of electrode pairs (lead), ie ischemia develops
in a small portion of the heart, coronary insufficiency is also limited and can be
rapidly corrected with drug therapy.
• Coronary artery stenosis is considered severe if symptoms on the ECG occur
during moderate heart rate and power expenditure, with or without pain. If
suspected multiple checkers my shrinking koronerograf of (coronary
angio-graphy) is required. However, if blood pressure is appropriate, ECG
disturbances are not common, arousal disturbances (additional beats) are mild,
and ECG returns to normal quickly, high-dose anti-angina medication may be
administered before deciding to refer to coronaryography. Indeed, it is
known that the ischemia threshold always occurs at the same heart rate in
repeated tests and can be increased with drugs such as beta-blockers or nitro
compounds.
If the patient’s complaints arouse suspicion and severe disturbances occur in
the ECG even with a slight exertion, lesion in many vessels should be
considered and coronary angiography should be performed.
• In cases where the disease is most severe, signs of ischemia appear very
early. These symptoms, which appear in the first 2-3 minutes, disappear
very slowly (over 10 minutes) with rest. In this case, coronary
angiography should be performed without delay, because most likely the part of
the coronary artery root before it splits into two branches is narrowed and
a coronary bypass surgery
may be decided based on the coronary angiography result ..