seen in chronic coronary disease hearts. A - horizontal; B - oblique descending; B - with an arc turned convex upwards; G - oblique ascending; D - trough-shaped; E - elevation of the ST segment.

1. Horizontal displacement of the ST segment. It is characterized by a decrease in the ST segment below the isoline with its horizontal location. The ST segment changes into a positive biphasic (- +) flattened or negative T wave.
2. Oblique downward shift of the ST segment (from R to T). As you move away from the QRS complex, the degree of displacement of the ST segment downwards from the isoline gradually increases. The ST segment becomes negative, biphasic (+) flattened, or positive T.
3. Offset of the ST segment downwards from the isoline with an arc turned convex upwards. The depression of the ST segment is not expressed equally throughout its entire length, but has the shape of an arc, the bulge of which is directed upwards. The ST segment becomes positive, biphasic (+), flattened, or T wave negative.
4. Oblique upward displacement of the ST segment (from S to T). The greatest depression of the ST segment is observed in this case immediately after the end of the QRS complex. Following this, the ST segment gradually rises to the isoline and usually passes into a positive or smoothed T wave.
5. Trough-shaped displacement of the ST segment. This type of ST segment displacement has the shape of an arc, the convexity of which is directed downwards. It is also observed in the treatment of cardiac glycosides. The ST segment becomes a flattened biphasic (- +) or upright T wave.

For chronic ischemic heart disease, the first two types of ST segment displacement are most specific, i.e. horizontal and oblique downward.

"Guide to electrocardiography", V.N. Orlov

The shift of the ST segment relative to the isoelectric line down (depression) is the reason for a more detailed examination of the patient, since the presence of such a change makes it possible to suspect ischemia of the heart muscle.

It should be remembered that the analysis of this segment alone from the overall picture of the electrocardiogram is not informative enough. A correct conclusion is possible only after a comprehensive detailed analysis of the recording in all leads.

What is the ST segment?

A segment on a cardiogram is a section of the curve located between adjacent teeth. The ST segment is located between the negative S wave and the T wave.

The ST segment is a fragment of the electrocardiogram curve, which reflects the period during which both ventricles of the heart are fully involved in the excitation process.

The duration of the ST segment on the ECG depends on the heart rate and changes with it (the higher the heart rate, the shorter the duration of this section on the cardiogram).

Each of the sections of the electrocardiographic curve has its own diagnostic value:

On a normal ECG in the limb leads, the ST segment has a horizontal direction and is located on the isoelectric line. However, its position is also recognized as a variant of the norm and its position is slightly higher than the isoelectric line (one and a half to two cells). This picture on the electrocardiogram is often combined with an increase in the amplitude of the positive T wave.

The greatest attention to this segment in the analysis of the electrocardiogram is given in case of suspected coronary heart disease and in the diagnosis of this disease, since this section of the curve is a reflection of oxygen deficiency in the heart muscle. Thus, this segment reflects the degree of myocardial ischemia.

ST segment depression

The conclusion about depression of the ST segment is made when it is located below the isoelectric line.

The descent of the ST segment below the isoline (its depression) can also be registered on the cardiogram of a healthy person, in this case, the position of the electrocardiogram curve in the ST segment does not fall below half a millimeter of the isoelectric line.

Causes

When analyzing an electrocardiogram, it must be taken into account that the modification of some of its elements can be caused by medications that the patient takes, as well as deviations in the electrolyte composition of the blood.

The shift of the ST segment down relative to the isoelectric line is a non-specific sign. This electrocardiographic phenomenon is observed in various leads in a number of conditions:

• Subendocardial or acute transmural ischemia (with acute myocardial infarction).
• Acute myocardial ischemia of the anterior wall of the left ventricle. It may also be indicated by ST elevation in the chest leads.
• Acute ischemia of the lower wall.
• Impact result medicines class of cardiac glycosides.
• Hyperventilation of the lungs (an excess of oxygen in them).
• Reduced potassium content in the peripheral blood (hypokalemia) - in this case, there is a possibility of an additional U wave.
• Hypertrophic changes in the left ventricle, which in some cases can be interpreted as a sign of its overload.
• The horizontal downward displacement of this segment is specific for the chronic course of coronary circulation insufficiency with myocardial ischemia.
• Vegetovascular dystonia.
• Pregnancy. During this period, a shift of the ST segment below the isoelectric line may be recorded against the background of tachycardia; the degree of depression in these cases does not exceed 0.5 mm.

A change in the ST-T complex in the form of its downward displacement relative to the isoelectric line can also be caused by a complex of reasons. For example, in a patient with myocardial hypertrophy (of any origin) and receiving therapy in the form of cardiac glycosides, there is a possibility of acute subendocardial ischemia.

The detection of ST segment depression is the reason for a thorough analysis of the electrocardiogram recording in all leads for a more accurate diagnosis of the localization of the lesion.

Clinical manifestations

In typical cases, ischemia (hypoxia) of the myocardium is manifested by pressing pains, discomfort, burning sensation in the chest area. Irradiation is characteristic pain in the region of the back and left upper limb. A painless form of myocardial ischemia is also possible, manifested by discomfort in the retrosternal space, tachycardia, a decrease or increase in blood pressure, heartburn, shortness of breath.

In the differential diagnosis of ischemic myocardial damage with VVD, the features clinical picture: vegetovascular dystonia is characterized by ST depression in a young patient, more often women, against the background of an increase in heart rate, in the absence of symptoms typical of angina pectoris. In this case, changes in the electrocardiogram are regarded as "non-specific" or as "signs of increased influence of the sympathetic nervous system".

With transient ischemia, Holter monitoring (ECG recording during the day) helps to make a diagnosis. The Holter displays all episodes of oxygen starvation of the heart muscle of patients that took place during the day.

Holter application

Treatment of conditions associated with ST segment depression

In order for the treatment to be effective, it is necessary to act directly on the cause of hypoxia, which is determined using special examination methods. Possible reasons are as follows:

• atherosclerotic vascular lesions;
• unbalanced diet containing excessive amounts of cholesterol;
• emotional overstrain;
• the presence of bad habits;
• sedentary lifestyle;
• excessive physical activity with the unpreparedness of the body;
• metabolic disorders in the body leading to obesity;
• diabetes.

In the treatment of myocardial ischemia, complex therapeutic regimens are used, consisting of the following drugs described in the table:

With insufficient efficiency conservative therapy apply surgical methods treatment:

• stenting coronary arteries and (or) their branches;
• coronary artery bypass grafting.

In the treatment of vegetovascular dystonia, the main role belongs to the normalization of the excitability of the nervous system. The amino acid Glycine is capable of normalizing the metabolism of nervous tissue. The beneficial effect of this substance on the nervous tissue helps to reduce the astheno-neurotic component.

It is also advisable to use nootropic drugs with an additional sedative effect.

If there are tachycardia or tachyarrhythmia in vegetative dystonia, the use of Corvaldin, Corvalol, and potassium preparations is indicated.

For effective treatment of vegetative-vascular dystonia, it is necessary to observe a protective regime: giving up bad habits, a balanced diet, combating physical inactivity, and eliminating stress. High efficiency, especially in complex therapy, show massage, physio and acupuncture.

When problems start cardiovascular system, the most reasonable decision is to contact a cardiologist. In the conditions of the hospital department, doctors can provide qualified assistance and conduct appropriate diagnostics. What happens to the heart if the electrocardiogram shows st segment depression on the ECG? What are the reasons for the deviation from the norm? Is any therapy needed? Is there a risk to human life and health?

Why do an ECG

Analysis of the state of the ST segment in the picture of the electrocardiogram remains a very relevant method modern diagnostics. With the help of an ECG, it is possible to detect cardiological pathologies at an early stage and begin their therapy. Therapeutic practice shows that the treatment and prognosis of many of these diseases depend on the stage of pathology they are diagnosed at.

Timely diagnosis of cardiac pathologies will protect against serious complications

It is possible to assess how much the shift of the ST segment has occurred only in combination with other parameters of the cardioharmma. Depression or elevation by itself does not necessarily indicate pathology, it may be part of the norm.

Considering the results of electrocardiography, one cannot ignore the symptoms that appear. The displacement of the ST segment may be associated with non-coronary changes in the myocardium.

Important! In rare cases, segment displacement may be a sign of acute coronary syndrome. This requires an emergency ambulance.

General Information about Segment Offset

When a person is healthy, their ECG is normal. Elevation of the st segment (rise) or decrease may indicate pathologies within the body. Normally, the st segment is located on the isoline, although there is also a certain range of acceptable indicators.

st depression is acceptable in limb leads up to 0.5 mm. Readings greater than or equal to 0.5 in leads V1-V2, 0.5 are considered abnormal.

The st segment elevation on the limb leads should be less than 1 mm. For leads V1-V2, up to 3 mm is considered the norm, and for V5-V6, up to 2 mm.

Where does this information apply?

Knowing the rate of elevation of the st segment on the ECG helps in diagnosing some serious cardiac pathologies: myocardial infarction, coronary heart disease, myocardial hypertrophy, LV aneurysm, pericarditis, myocarditis, pulmonary embolism, etc.

So, with heart attacks, there is no decrease in the st segment. This indicator can increase to 2-3 mm at a rate of up to 1. In addition to the growth of the ST segment, an abnormal Q wave may appear on the electrocardiogram picture.

It is effective to use a troponin test when a heart attack is suspected. When there is a significant displacement of the ST segment, last analysis allows you to clarify the diagnosis. If the test is negative, the patient has not had a heart attack, and acute coronary disease requires treatment.

In order to properly diagnose and prescribe effective treatment, it is important for a cardiologist to carefully read the electrocardiogram. There are some rules, given which, you can help the patient qualitatively.

First of all, the ability of the heart to conduct electrical impulses is analyzed. The frequency and rhythm of the pulse is calculated, the regularity of heart contractions is assessed. Then the cardiologist pays attention to the work of the pacemaker and determines how well the impulses pass through the conduction paths of the heart.

After conducting these studies, the cardiologist evaluates the position of the electrical axis, considers the turns of the heart around the longitudinal, transverse and anteroposterior axes. At the same stage, the R wave is evaluated.

The next step in deciphering the electrocardiogram is to consider the state of the QRS-T complex. When evaluating the ST segment, the J point is important (the moment the S wave passes into the ST segment).

The shape of the arc that the J point forms to the end of the ST segment determines the presence of pathology. If it is concave, then the deviation is benign. Convex - a sign of myocardial ischemia.

Causes of cardiac changes

Myocardial infarction and other serious cardiovascular pathologies do not develop overnight. Perhaps the person neglected the alarming symptoms for some time, or did not follow the recommendations of the attending physician. Some were not serious about such a diagnosis as coronary disease, underestimating the risks of pathology.

On the results of the electrocardiogram, deviations from the norm may appear according to different reasons. More often this study gives a reliable picture of the work of the heart muscle. Although errors do occur, they are very rare.

Important! ST segment depressive symptoms sometimes appear even in healthy people. If, in addition to changes in the ECG, there are no negative symptoms, we can talk about the physiological norm. Although periodic visits to a cardiologist and monitoring the condition of the heart should not be neglected.

Deviations from the norm in the picture of the electrocardiogram may appear if the procedure is performed incorrectly. This situation is possible with improper application of the electrodes. In this case, there is not enough contact, and the device takes unreliable data.

Other non-cardiac causes of ECG abnormalities:

• electrolyte disturbances;
• hyperventilation of the lungs;
• abuse of medicines, including narcotic action;
• frequent use of alcohol;
• drinking cold water.

The development of any pathology can be suspended under the condition of timely diagnosis and competent treatment. To do this, when the slightest unpleasant symptoms in the area of ​​​​the heart, it is recommended to visit a therapist to get a referral for an examination. So you can prevent the development of serious and dangerous pathologies.

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How to decipher the ECG analysis, the norm and deviations, pathologies and the principle of diagnosis

Reflects the spread of the excitation wave to the basal sections of the interventricular septum, right and left ventricles.

1. The optional negative wave following the R wave may be absent in the limb leads and V5-6.

2. In the presence of several teeth, it is designated respectively S,

S`, S``, S```, etc.

3. Duration less than 0.04 sec, amplitude in chest

leads is greatest in leads V1-2 and gradually decreases to V5-6.

ST segment

Corresponds to the period when both ventricles are completely covered by excitation, measured from the end of S to the beginning of T (or from the end of R in the absence of an S wave).

1. The duration of ST depends on the pulse rate.

2. Normally, the ST segment is located on the isoline, ST depression

allowed no more than 0.5 mm (0.05 mV) in leads V2-3 and no more than 1 mm (0.1 mV) in other leads.

3. Its rise should not exceed 1 mm in all leads except V2-3.

4. In leads V2-3, ST segment elevation ≥2 mm (0.2 mV) should be considered pathological in people older than 40 years, in people younger than 40

years ≥2.5 mm (0.25 mV) in men and ≥1.5 (0.15 mV) in women, respectively.

T wave

Reflects the processes of ventricular repolarization. This is the most labile tooth.

1. Normally, the T wave is positive in those leads where the QRS complex is represented predominantly by the R wave.

2. In a normal heart position, the T wave is positive in leads I, II, III, aVL, and aVF and negative in lead aVR.

3. T III can be reduced, isoelectric, weakly negative when the electrical axis of the heart deviates to the left.

4. In lead V 1, the T wave with the same frequency can be negative, isoelectric, positive or

biphasic, in lead V2 more often positive, in leads V3-6 always positive.

With a qualitative description, a low T wave should be distinguished if its amplitude is less than 10% of the R wave amplitude in this lead; flattened at amplitude from -0.1 to 0.1 mV; inverted T wave in leads I, II, aVL, V2 -V6, if its amplitude is from -0.1 to -0.5 mV; negative with an amplitude of -0.5 mV or more.

QT Interval (QRST)

Reflects the electrical systole of the heart. Measured from the beginning of the Q wave (or R if Q is absent) to the end of the T wave.

1. Duration depends on gender, age, rhythm frequency. Normal QT value (corrected QT; QTc)

2. Normal QT values ​​fluctuate within 0.39 - 0.45 sec.

3. If measurements are made in different leads, the basis

the largest value is taken (usually in lead V2 - V3).

4. A prolongation of the QT interval is considered to be 0.46 seconds or more in women, 0.45 seconds or more in men, and a shortening of 0.39 seconds or less.

U wave

Inconstant, small amplitude (1–3 mm or up to 11% of the T wave amplitude) wave, concordant (unidirectional) to the T wave, following it after 0.02–0.04 sec. Most pronounced in leads V2 -V3, more often with bradycardia. The clinical significance is not clear.

TR segment

Reflects the diastolic phase of the heart. Measured from the end of the T wave (U) to the beginning of the P wave.

1. Located on the isoline, the duration depends on the frequency of the rhythm.

2. With tachycardia, the duration of the TR segment decreases, with bradycardia it increases.

RR interval

Describes the duration of the full cardiac cycle- systole and diastole.

1. To determine the heart rate, divide 60 by the RR value, expressed in seconds.

IN in cases where the rhythm frequency in one patient differs in a short period of time (for example, with atrial fibrillation),

you should determine the maximum and minimum rhythm rates from the largest and smallest RR values ​​or calculate the average rhythm rate from 10 consecutive RRs.

ECG changes in angina pectoris and chronic ischemic heart disease, they arise not due to a violation of the coronary arteries themselves, but due to increasing myocardial anoxia, due to a lack of blood supply. The manifestations of this condition are nonspecific and may be present in other diseases. Therefore, a clear diagnosis is made on the basis of a complex of ECG signs in combination with clinical symptoms and the results of functional tests.

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ECG phenomena in angina pectoris and coronary artery disease

With coronary artery disease characteristic changes in the ST segment and T wave are noted on the ECG.

Insufficiency of the coronary arteries and a decrease in the flow of arterial blood to the myocardium usually cause depression and a change in the shape of the ST segment, which normally smoothly, unsharply passes into the ascending knee of the T wave. IHD (ischemic heart disease) is accompanied by a clear and steep transition of the ST segment into the T wave. This is early diagnostic sign development of coronary artery disease in a patient. Further progression of the disease will be combined with depression of the ST segment below the isoline, which is associated with subendocardial damage due to myocardial ischemia and characteristic changes in the T wave.

ST segment changes

There are 5 types of ST segment depression:

1. 1. Horizontal displacement of the ST segment. It is manifested by its displacement almost parallel to the isoline. The ST segment may change into a positive or negative, isoelectric or biphasic T wave.
2. 2. Oblique downward displacement of the ST segment. As it extends downward from the isoelectric line and away from the QRS complex, the degree of ST segment depression gradually increases. Sometimes such a shift is called from R to T. Then the segment passes into a positive or negative, isoelectric or biphasic T wave.
3. 3. Displacement of the ST segment downward from the isoline with an arc facing upwards with a convexity. The decrease in the segment is expressed unequally throughout its length, resembling an arc in shape, with a bulge facing upwards. The ST segment changes into a positive or negative, isoelectric or biphasic T wave.
4. 4. Oblique upward displacement of the ST segment. The greatest depression in this variant is recorded immediately after the QRS complex. After that, the segment smoothly rises to the isoelectric line and passes into a positive or biphasic T wave.
5. 5. Trough-shaped displacement of the ST segment. This type resembles an arc in shape, with a bulge facing downwards, and passes into a positive, isoelectric or biphasic T wave.


Most often with angina pectoris, horizontal and oblique downward displacement of the ST segment occurs.

The severity of ST segment displacement is directly proportional to the severity of ischemic changes and coronary insufficiency. Its downward displacement from the isoline by 1 mm or more in chest leads, more than 0.5 mm in standard leads reliably indicates the presence of myocardial ischemia. A slight depression up to 0.5 mm is also found in healthy people.

With angina pectoris and coronary heart disease, elevation (rise) of the ST segment can also be observed. Usually in shape it resembles an arc with a convexity facing downwards. The ST segment in this case passes into a positive or isoelectric T wave. A diagnostically significant rise in the ST segment should be at least 1 mm. In this case, differential diagnosis with myocardial infarction is carried out.

ST changes characteristic of angina pectoris and coronary artery disease are most often localized in the left chest leads V4-V6 and leads II, III, aVF, I, aVL.

In acute myocardial infarction and acute coronary insufficiency, similar phenomena of the ST segment occur. The difference between the chronic course of coronary artery disease and angina pectoris will be the absence of changes in dynamics, stability for a long time.



T wave changes

The most specific change in the T wave in angina pectoris and coronary artery disease is the "coronary" T wave (characterized by a pointed, symmetrical shape), often negative. This shape of the tooth is associated with the development of transmural myocardial ischemia. Negative T waves characteristic of CAD are often deep, with an amplitude of 5 mm or more.

Sometimes myocardial ischemia manifests itself as giant positive T waves - a high "coronary" T wave. This change occurs in other diseases (hyperkalemia, pericarditis) and is not pathognomonic.

And also with coronary artery disease and angina pectoris, two-phase T waves can be recorded: + - or - +. More often, the recording of such teeth occurs when the recording electrode is located peripherally from the ischemic zone.

In chronic ischemic heart disease and angina pectoris, a smoothed, reduced, isoelectric T wave is sometimes recorded. More often, a decrease occurs in most of the main leads.



Another sign of coronary heart disease is the ratio of T V1 > T V6 and T I< T III.

Most often, pathological T waves are recorded in the left chest leads, in I, aVL, and also in III, aVF leads. In the right chest leads V1-V2, changes in the T wave with angina pectoris are observed much less frequently.

Negative T waves should be differentiated during ischemia and during dynamic changes without organic damage myocardium. To do this, a Valsalva test, a test with hyperventilation, potassium, obzidan, an orthostatic test are performed, and if the negative T wave turns into a positive one, this indicates against the presence of angina pectoris and coronary artery disease.

The ECG conclusion is not a diagnosis. The final verdict is made by a cardiologist based on clinical symptoms, ECG signs, as well as the results of functional tests and studies.



Additional ECG symptoms

These symptoms may not always occur or be combined with other diseases not associated with coronary artery disease and angina pectoris. Only by these signs it is impossible to assume the presence or absence of the disease, they are only additional markers to the main ECG symptoms of coronary artery disease.

Signs that indicate the likely presence of coronary artery disease and angina pectoris include:

• the presence of a negative or biphasic U wave;
• some increase in the duration of the P wave;
• an increase in the QT interval due to the lengthening of the electrical systole of the ventricles;
• a sharp deviation between electric axes QRS complex and T wave;
• various disturbances of a rhythm and intracardiac conductivity are often observed;
• various disorders of intraventricular conduction, manifested by splitting of the QRS complex;

ECG changes during an angina attack

During the onset of an attack of heart pain during angina pectoris, ST segment depression, combined with T wave inversion, can be observed on the ECG. But usually these are incoming changes that are not always possible to register due to their short duration. After the end of the attack, the ECG usually returns to its original form. Changes in the myocardium with the onset of pain are associated with diffuse myocardial hypoxia.

Usually an attack of angina pectoris is provoked physical activity, emotional outburst, stress.

Features in Prinzmetal's angina

This is a special variant of angina in which the attack occurs at rest or during normal daily activities and is not associated with any kind of stress.

The ECG is characterized by the presence of an ST rise with a transition to a positive T wave. As a result, a monophasic curve is recorded. On the opposite wall of the myocardium there will be reciprocal changes (the reverse of the existing ones), i.e., a decrease in the ST segment.

Changes in Prinzmetal's angina persist for some time, and then return to the initial level. It is assumed that this is due to the coming spasm of the coronary arteries.