Heart attack on ecg - signs and interpretation. The value of ECG in the diagnosis of myocardial infarction ECG signs of a typical variant of the course of myocardial infarction

I. Mogelwang, M.D. Cardiologist at the Intensive Care Unit of Hvidovre Hospital 1988

Ischemic heart disease (CHD)

Main cause of coronary artery disease- obstructive damage to the main coronary arteries and their branches.

The prognosis for IHD is determined by:

the number of significantly stenotic coronary arteries

functional state of the myocardium

ECG provides the following information about the state of the myocardium:

potentially ischemic myocardium

ischemic myocardium

acute myocardial infarction (MI)

previous myocardial infarction

MI localization

MI depth

IM sizes

Information that matters for treatment, control and prognosis.

left ventricle

In IHD, the myocardium of the left ventricle is primarily affected.

The left ventricle can be divided into segments:

Septal segment

Apical segment

Lateral segment

Posterior segment

lower segment

The first 3 segments make up the anterior wall and the last 3 the posterior wall. The lateral segment can thus be involved in an anterior wall infarction as well as a posterior wall infarction.

SEGMENTS OF THE LEFT VENTRICLE

ECG LEADS

ECG leads can be unipolar (derivatives of one point), in which case they are denoted by the letter "V" (after the initial letter of the word "voltage").

Classic ECG leads are bipolar (derivatives of two points). They are designated by Roman numerals: I, II, III.

A: reinforced

V: unipolar lead

R: right (right hand)

L: left (left hand)

F: leg ( left leg)

V1-V6: unipolar chest leads

ECG leads reveal changes in the frontal and horizontal planes.

	hand to hand	Lateral segment, septum
	Right arm -> left leg
	Left arm -> left leg	lower segment
	(Reinforced unipolar) right arm	Attention! Possible misinterpretation
	(Reinforced unipolar) left arm	Lateral segment
	(Reinforced unipolar) left leg	lower segment
	(Unipolar) at the right edge of the sternum	Septum/Posterior segment*
	(Unipolar)
	(Unipolar)
	(Unipolar)	tip
	(Unipolar)
	(Unipolar) on the left middle axillary line	Lateral segment
* - V1-V3 mirror image of posterior segment changes

ECG leads in the frontal plane

ECG leads in the grizontal plane

MIRROR IMAGE(with specific diagnostic value found in leads V1-V3, see below)

Cross section of the right and left ventricles & Segments of the left ventricle:

Relationship between ECG leads and segments of the left ventricle

Depth and dimensions

QUALITATIVE CHANGES OF ECG

QUANTITATIVE ECG CHANGES

LOCALIZATION OF INFARCTION: ANTERIOR WALL

LOCALIZATION OF INFARCTION: BACK WALL

V1-V3; FREQUENT DIFFICULTIES

Infarction and bundle branch block (BNP)

BNP is characterized by a wide QRS complex (0.12 sec).

Right-branch block (RBN) and left-branch block (LBN) can be distinguished by lead V1.

RBN is characterized by a positive wide QRS complex, and LBN is characterized by a negative QRS complex in lead V1.

Most often, the ECG does not carry information about a heart attack in LBBB, in contrast to RBN.

ECG changes in myocardial infarction over time

Myocardial infarction and silent ECG

Myocardial infarction can develop without the appearance of any specific ECG changes in the case of LBBB, but also in other cases.

ECG options for myocardial infarction:

subendocardial MI

transmural MI

no specific changes

ECG for suspected coronary heart disease

Specific signs of coronary heart disease:

Ischemia/Infarction?

In case of a heart attack:

Subendocardial/transmural?

Localization and dimensions?

Differential Diagnosis

ECG DIAGNOSIS KEY FOR CORONARY HEART DISEASE

PD KopT - suspected KopT

States:

ECG symbols:

1. Anterior segment ischemia 2. Ischemia of the lower segment 3. Subendocardial inferior MI 4. Subendocardial inferior-posterior MI 5. Subendocardial inferior posterolateral MI 6. Subendocardial anterior infarction (common) 7. Acute inferior MI 8. Acute posterior MI 9. Acute fart MI 10. Transmural inferior MI 11. Transmural posterior MI 12. Transmural anterior MI (common) (septal-apical-lateral) * The mirror image (zero) of ST G is visible not only with posterior MI, in this case it is called reciprocal changes. For simplicity, this is released in context. The mirror image of ST G and ST L cannot be distinguished.

On the ECG with myocardial infarction (photo 1), doctors clearly see signs of necrosis of the heart tissue. A cardiogram in case of a heart attack is a reliable diagnostic method and allows you to determine the degree of damage to the heart.

Deciphering the ECG for myocardial infarction

An electrocardiogram is a safe research method, and if a heart attack is suspected, it is simply irreplaceable. ECG in myocardial infarction is based on a violation of cardiac conduction, i.e. in certain areas of the cardiogram, the doctor will see abnormal changes that indicate a heart attack. To obtain reliable information, doctors use 12 electrodes when taking data. Cardiogram for myocardial infarction(photo 1) registers such changes based on two facts:

• in a person with a heart attack, the process of excitation of cardiomyocytes is disrupted, and this happens after cell necrosis;
• in the tissues of the heart affected by a heart attack, is disturbed electrolyte balance- potassium largely leaves damaged tissue pathologies.

These changes make it possible to register lines on the electrocardiograph, which are signs of conduction disturbance. They do not develop immediately, but only after 2-4 hours, depending on the compensatory capabilities of the body. Nevertheless, the cardiogram of the heart during a heart attack shows the accompanying signs, by which it is possible to determine the violation of the heart. The cardiological ambulance team sends a photo with a transcript to the clinic where they will receive such a patient - cardiologists will be prepared in advance for a serious patient.

Looks like myocardial infarction on ECG(photo below) as follows:

• the complete absence of the R wave or its significant decrease in height;
• extremely deep, dip Q wave;
• elevated S-T segment above the level of the isoline;
• the presence of a negative T wave.

An electrocardiogram also shows the various stages of a heart attack. Heart attack on EKG(photo in gal.) can be subacute, when changes in the work of cardiomyocytes are just beginning to appear, acute, acute and at the stage of scarring.

Also, the electrocardiogram allows the doctor to evaluate the following parameters:

• to diagnose the fact of a heart attack;
• determine the area where pathological changes have occurred;
• establish the prescription of the changes that have occurred;
• decide on the tactics of treating the patient;
• predict the possibility of death.

Transmural myocardial infarction is one of the most dangerous and severe types of heart damage. It is also called macrofocal or Q-infarction. Cardiogram after myocardial infarction(photo below) with a macrofocal lesion shows that the zone of death of heart cells captures the entire thickness of the heart muscle.

myocardial infarction

Myocardial infarction is a consequence of coronary heart disease. Most often, atherosclerosis of the heart vessels, spasm or blockage leads to ischemia. happen heart attack(photo 2) may also result from surgery if an artery is ligated or angioplasty is performed.

Ischemic infarction goes through four stages of the course of the pathological process:

• ischemia, in which the cells of the heart stop receiving the necessary amount of oxygen. This stage can last quite a long time, since the body turns on all the compensatory mechanisms to ensure the normal functioning of the heart. The immediate mechanism of ischemia is the narrowing of the heart vessels. Up to a certain point, the heart muscle copes with such a lack of blood circulation, but when thrombosis narrows the vessel to a critical size, the heart is no longer able to compensate for the shortage. This usually requires a narrowing of the artery by 70 percent or more;
• damage occurring directly in cardiomyocytes, which begins within 15 minutes after the cessation of blood circulation in the damaged area. A heart attack lasts approximately 4-7 hours. It is here that the patient begins the characteristic signs of a heart attack - pain behind the sternum, heaviness, arrhythmia. Massive heart attack(photo below) - the most severe outcome of the attack, with such damage, the necrosis zone can reach up to 8 cm in width;
• necrosis - necrosis of heart cells and the cessation of their functions. In this case, the death of cardiomyocytes occurs, necrosis does not allow them to perform their functions;
• scarring - replacement of dead cells with connective tissue formations that are not able to take on the function of precursors. Such a process begins almost immediately after necrosis and gradually for 1-2 weeks a connective tissue scar of fibrin fibers is formed on the heart at the site of damage.

Hemorrhagic cerebral infarction is a related condition in terms of damage mechanisms, however, it represents the release of blood from the vessels of the brain, which interfere with the work of cells.

Heart after a heart attack

Heart after myocardial infarction(photo 3) undergoes a process of cardiosclerosis. Connective tissue, which replaces cardiomyocytes, turns into a rough scar - it can be seen by pathologists during the autopsy of people who have had a myocardial infarction.

The scar after myocardial infarction has a different thickness, length and width. All these parameters affect the further activity of the heart. Deep and large areas of sclerosis are called extensive infarcts. Recovery after such a pathology is extremely difficult. With microsclerosis, a heart attack, like, can leave minimal damage. Often, patients do not even know that they have suffered such a disease, since the symptoms were minimal.

Scar on the heart after a heart attack(photo in gal.) does not hurt in the future and does not make itself felt for about 5-10 years after a heart attack, however, it provokes a redistribution of the heart load to healthy areas, which must now be performed more work. After a certain time, the heart after a heart attack (photo below) looks worn out - the organ cannot perform the load, ischemic disease heart disease in patients is aggravated, there are pains in the heart, shortness of breath, they quickly get tired, constant medical support is required.

Myocardial infarction photo gallery

ST elevation myocardial infarction (STEMI) depending on the localization can be attributed to one of two types: MI of the anterior localization and MI of the posterior localization.

Anterior MI develops due to occlusion of the left coronary artery and/or its branches

With anterior MI, more distinct ECG changes are recorded in the chest leads than in the limb leads.

In acute, or "fresh" myocardial infarction (MI) of the anterior localization, a distinct ST segment elevation and a positive T wave (monophasic deformity) are recorded, especially distinct in the chest leads V1-V6, depending on the size of the infarct zone. The Q wave may be large.

With the "old" myocardial infarction (MI) of the anterior localization, monophasic deformation of the ST segment is no longer present. A large Q wave, ST segment depression, and a negative T wave are recorded in all or some of the chest leads V1-V6, depending on the size of the infarct zone.

The result of a blood test for markers of myocardial necrosis is positive.

At myocardial infarction(MI) of anterior localization, the necrosis zone is located in the anterior wall of the left ventricle. RV infarction is extremely rare. Anterior MI is caused by occlusion of the left coronary artery or its branches.

ECG signs of myocardial infarction(MI) of the anterior wall in the chest leads and limb leads are different. First of all, it is necessary to evaluate ECG changes in limb leads. In leads I, II, III, aVR, aVL and aVF, the signs of MI are less pronounced. In the acute phase of MI, only a slight rise in the ST segment is possible in I, and sometimes in II and aVL leads; the T wave in these leads is positive. So, in these leads, a monophasic deformation of the ST segment can be recorded, but less pronounced than in the chest leads.

Distinct changes with myocardial infarction(MI) of anterior localization are recorded in the chest leads. In leads V1-V4 or V4-V6, and with extensive MI of the anterior localization, clear signs of MI are recorded in leads V1-V6. Depending on the size of the MI zone, these changes can be over the entire anterior wall, i.e. the larger the infarct zone, the more leads in which there are characteristic changes.

IN chest leads V1-V6 with extensive myocardial infarction(MI) of the anterior localization, a significant rise in the ST segment and a positive T wave (monophasic deformation) are recorded. This monophasic deformity in the chest leads is the most important diagnostic sign acute myocardial infarction of the anterior wall. Since these leads are located directly above the affected myocardium, ST-segment elevation in many cases of anterior wall MI is more pronounced than in posterior wall MI and cannot be missed.

It is assumed that the less time elapsed after a heart attack, the more ST-segment elevation and positive T wave. Thus, the T wave is positive and can be very high. Sometimes an asphyxial T wave may be recorded.

Large Q wave optional, although it may appear already in the acute stage of the disease. A large Q wave is characterized by being very deep or wide, or a combination of both. The R wave is usually small or barely visible.

After the lapse of acute phase or when "old" myocardial infarction(MI) of the anterior wall, ST-segment elevation is not detected, but a deep Q wave is recorded in leads I and aVL. In these leads, the T wave is often negative. However, in the limb leads, the described changes, as in the case of the acute stage of MI, are not so clearly expressed.

In the chest leads, characteristic signs "old" myocardial infarction(MI), as well as "fresh" myocardial infarction (MI), are more pronounced. So, in leads V1-V4, and with extensive MI in leads V1-V6, a widened and deep Q wave is recorded (a sign of necrosis). These Q wave changes are more pronounced in anterior infarction than in inferior MI.

Particularly characteristic of myocardial infarction (THEM) anterior localization is a decrease in the amplitude of the R wave, i.e. the small R waves that are normally present in leads V1-V3 disappear and the QS complex appears. This is an important sign of MI that catches the eye. If the Q wave is very large, it may sometimes be followed by a very small R wave, which, however, may be completely absent. Later, the R wave may reappear, gradually increasing in amplitude.

Along with a large Q wave in the diagnosis of "old" myocardial infarction (MI), an important role is also played by the change in the ST interval. So in typical cases, a deep, pointed negative T wave (coronary T wave) appears in leads V1-V6. In addition, ST segment depression is also noted. The more time has passed since the onset of anterior MI, the less the depth of the negative T wave and the less depression of the ST segment in the chest leads.

At myocardial infarction(MI) of both anterior and posterior localization in severe cases in the acute stage, a left atrial P wave may appear.

There are also possible heart rhythm disturbances in the form of sinus tachycardia, ventricular extrasystole and ventricular tachycardia.

ECG features in anterior wall myocardial infarction:
Occlusion of the left coronary artery or its branches
Myocardial necrosis of the anterior wall
In the acute stage: ST segment elevation and positive T wave (in all leads V1-V6 or in some of them, depending on the size of the necrosis zone)
In the chronic stage: deep negative T wave and large Q wave
Positive result blood test for creatine kinase and troponins

Myocardial infarction (MI) of the anterior wall with ST segment elevation (stage I) (acute anterior wall MI).
A significant rise in the ST segment and a positive T wave, recorded primarily in leads V1-V4, indicate an acute stage of anterior wall MI.
Additional data: turn of the electrical axis of the heart to the left (S> R in lead II, left ECG type), short PQ interval (0.11-0.12 s), for example, in lead II.
"Old" myocardial infarction (MI) of the anterior wall. Large Q wave in leads V1-V3.
The T wave in leads I, aVL, as well as V2-V6 is negative.
The absence of a distinct ST segment elevation in this case makes it possible to diagnose an “old” myocardial infarction (MI) of anterior localization.
ECG and coronary angiogram of a patient 4 years after myocardial infarction (MI).
"Old" extensive MI of the anterior wall, complicated by the formation of an aneurysm.
Small Q wave, slight ST elevation, and emerging T wave inversion in leads I and aVL.
Large Q wave, prolonged ST elevation, and positive T wave in leads V2-V5 (signs of LV aneurysm).

Electrocardiography (ECG) is a widely used method for diagnosing cardiovascular diseases. During the examination, the difference in electrical potentials that occur in the cells of the heart during its work is recorded.

With myocardial infarction, a series appears on the ECG characteristic features, which can be used to suggest the time of onset of the disease, the size and localization of the lesion. This knowledge allows timely diagnosis and treatment.

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Cardiogram is normal

The ECG reflects the potential difference that occurs when the parts of the heart are excited during its contraction. Registration of impulses is carried out using electrodes installed on different parts of the body. There are certain leads that differ from each other in the areas from which the measurement takes place.

chest leads

Usually the cardiogram is taken in 12 leads:

• I, II, III - standard bipolar from limbs;
• aVR, aVL, aVF - reinforced unipolar limbs;
• V1, V2, V3, V4, V5, V6 - six unipolar chest.

In some situations, additional leads are used - V7, V8, V9. In the projection of each positive electrode there is a certain part of the muscular wall of the heart. By ECG change in any of the leads, it can be assumed in which of the departments of the organ the focus of damage is located.



ECG is normal, waves, intervals and segments

When the heart muscle (myocardium) relaxes, a straight line is fixed on the cardiogram - an isoline. The passage of excitation is reflected on the tape in the form of teeth that form segments and complexes. If the tooth is located above the isoline, it is considered positive, if below - negative. The distance between them is called the interval.

The P wave reflects the process of contraction of the right and left atria, the QRS complex registers the rise and fall of excitation in the ventricles. The RS-T segment and the T wave show how myocardial relaxation proceeds.



ECG for myocardial infarction

Myocardial infarction is a disease in which death (necrosis) of part of the muscle tissue of the heart occurs. The reason for its occurrence is an acute violation of blood flow in the vessels that feed the myocardium. The development of necrosis is preceded by reversible changes - ischemia and ischemic damage. Signs characteristic of these conditions can be recorded on the ECG at the onset of the disease.



ECG fragment with ST segment elevation, coronary T

With ischemia, the structure and shape of the T wave, the position of the RS-T segment change on the cardiogram. The process of restoring the initial potential in the cells of the ventricles in the event of a violation of their nutrition proceeds more slowly. In this regard, the T wave becomes taller and wider. It is called "coronary T". It is possible to register negative T in chest leads, depending on the depth and location of the lesion of the heart muscle.

Prolonged lack of blood flow in the myocardium leads to its ischemic damage. On the ECG, this is reflected in the form of a shift in the RS-T segment, which is normally on the isoline. With different localizations and volumes of the pathological process, it will either rise or fall.

Heart muscle infarction develops in the walls of the ventricles. If necrosis affects a large area of ​​the myocardium, they speak of a large-focal lesion. In the presence of many small foci - about small foci. Deterioration of indicators when deciphering the cardiogram will be detected in leads, the positive electrode of which is located above the site of cell death. Mirror-reciprocal changes are often recorded in opposite leads.



Large focal infarction

The dead area of ​​the myocardium is not reduced. In the leads fixed over the area of ​​necrosis, changes in the QRS complex are detected - an increase in the Q wave and a decrease in the R wave. Depending on the location of the lesion, they will be recorded in different leads.

A large-focal process can cover the entire thickness of the myocardium or its part located under the epicardium or endocardium. Total damage is called transmural. Its main sign is the appearance of the QS complex and the absence of the R wave. With partial necrosis of the muscle wall, pathological Q and low R are detected. The duration of Q exceeds 0.03 seconds, and its amplitude becomes more than 1/4 of the R wave.

With a heart attack, three pathological process that exist simultaneously - ischemia, ischemic injury and necrosis. Over time, the infarct zone expands due to the death of cells that were in a state of ischemic damage. When blood flow is restored, the area of ​​ischemia decreases.

The changes recorded on the ECG film depend on the time of development of the infarction. Stages:

1. 1. Acute - a period of several hours to two weeks after a heart attack.
2. 2. Subacute - a period of up to 1.5–2 months from the onset of the disease.
3. 3. Cicatricial - the stage during which the damaged muscle replaced by a connecting one.



Acute stage



ECG changes in myocardial infarction by stages

15–30 minutes after the onset of a heart attack, a zone of subendocardial ischemia is detected in the myocardium - a violation of the blood supply to the muscle fibers under the endocardium. High coronary T waves appear on the ECG. There is a shift of the RS-T segment below the isoline. These initial manifestations of the disease are rarely recorded, as a rule, patients do not yet seek medical help.

A few hours later, the damage reaches the epicardium, the RS-T segment shifts upward from the isoline and merges with T, forming a gentle curve. Further, in the departments located under the endocardium, a focus of necrosis appears, which rapidly increases in size. Pathological Q begins to form. As the infarct zone expands, Q deepens and lengthens, RS-T descends to the isoline, and the T wave becomes negative.

Subacute stage

The area of ​​necrosis stabilizes, the area of ​​ischemic damage decreases due to the death of some cells and the restoration of blood flow in others. The cardiogram shows signs of infarction and ischemia - pathological Q or QS, negative T. RS-T is located on the isoline. Gradually, the ischemic zone decreases and the amplitude of T decreases, it smooths out or becomes positive.

Cicatricial stage

The connective tissue that replaced the dead muscle tissue does not participate in excitation. The electrodes located above the scar fix the Q wave or the QS complex. In this form, the ECG is stored for many years or the entire life of the patient. RS-T is on the isoline, T is smoothed or slightly positive. Negative T-waves are also often observed over the replaced area.

Small focal infarction



Signs of a heart attack at different depths of myocardial damage

Small areas of damage in the heart muscle do not disrupt the excitation process. Pathological Q and QS complexes will not be determined on the cardiogram.

In small-focal infarction, changes on the ECG film are due to ischemia and ischemic damage to the myocardium. A decrease or increase in the RS-T segment is detected, negative T waves are recorded in the leads located next to the necrosis. Biphasic T waves with a pronounced negative component are often fixed. At death muscle cells located in the back wall, only reciprocal changes are possible - coronary T in V1-V3. Leads V7-V9, on which this area is projected, are not included in the diagnostic standard.

Widespread necrosis of the anterior left ventricle is seen in all chest leads, I and aVL. Reciprocal changes - a decrease in RS-T and a high positive T, are recorded in aVF and III.

The upper sections of the anterior and lateral walls are outside the recorded leads. In this case, the diagnosis is difficult, signs of the disease are found in I and aVL or only in aVL.

Back wall damage

Posterior diaphragmatic, or infarction of the lower wall of the left ventricle, is diagnosed by III, aVF and II leads. Reciprocal signs - possible in I, aVL, V1-V3.

Posterior basal necrosis is less common. Ischemic changes are fixed when additional electrodes V7-V9 are applied from the back. The assumption of a heart attack of this localization can be made in the presence of mirror manifestations in V1-V3 - high T, an increase in the amplitude of the R wave.

The posterior ventricular lesion is seen in leads V5, V6, II, III, and aVF. In V1-V3, reciprocal signs are possible. With a common process, changes affect III, aVF, II, V5, V6, V7 -V9.

To establish the diagnosis of "myocardial infarction", use special equipment - an electrocardiograph (ECG). The method by which the fact of this disease is established is quite simple and informative. It should be noted that portable versions of this equipment are also used in medicine, which make it possible to recognize damage to the patient's heart muscle at home to monitor the health of their loved ones, even without the involvement of a certified specialist. In medical institutions, multi-channel electrocardiographic equipment is used, which itself decrypts the received data.

Myocardial infarction type 2 - spasms and dysfunction of the circulatory system

Features of myocardial blood supply

An electrocardiogram or ECG shows a heart attack, which can happen for a variety of reasons.

First of all, I would like to note the mechanics of the blood flow. The myocardium is supplied with blood from the arteries, which start from the expanding initial part of the aorta, called the bulb. They fill with blood in the diastole phase, and in the other phase - systole - the blood flow ends by covering aortic valves, which come into action under the contraction of the myocardium itself.

From the left coronary (coronary) artery, 2 branches depart, which go in a common trunk to the left atrium. They are called the anterior descending and envelope branch. These branches feed the following parts of the heart:

1. left ventricle: posterior and anterolateral;
2. left atrium;
3. from the right ventricle partially anterior wall;
4. 2/3 of the interventricular septum;
5. AV node.

Right coronary artery(PC) originates from the same place as the left one. Then it goes along the coronary sulcus, passing it and bending around the right ventricle (RV), passes to the posterior cardiac wall and feeds the posterior interventricular sulcus.

The blood flowing through this artery allows the following areas to function:

1. right atrium;
2. posterior wall of the pancreas;
3. part of the left ventricle;
4. 1/3 of the interventricular septum (IVS).

Diagonal "highways" of blood depart from the right VA, which feed parts of the heart:

1. anterior wall of the left ventricle;
2. 2/3 MZHP;
3. left atrium (LA).

In half of the cases, another diagonal branch departs from the coronary artery, and in the other half - the median one.

There are several types of coronary blood supply:

1. In 85 percent of cases, the posterior wall is supplied from the right CA.
2. In 7-8% - from the left CA.
3. Uniform blood supply from the right and left CA.

With a competent "reading" of the cardiogram obtained during myocardial infarction, you need to see all the signs, understand the processes taking place in the heart, and interpret them accurately. There are two types of signs of a heart attack: direct and reciprocal.

Direct signs include those recorded by the electrode. Reverse signs (reciprocal) go as opposite to direct signs, register necrosis of the reverse heart wall. When analyzing a patient's electrocardiogram, it is important to know what an abnormal Q wave and an abnormal ST segment elevation are.

The Q wave is called pathological in the following conditions:

1. Available in leads V1-V.
2. In chest leads V4-V6 is 25 percent higher than R height.
3. In I and II it is 15% higher than R.
4. In III, the excess from R is 60%.

1. In all V-leads, the segment is 1 mm higher from the isoline, except for the chest.
2. In chest leads 1-3, the segment is exceeded by 2.5 mm from the isoline, and in leads 4-6 to a height of more than 1 mm.

To prevent the expansion of the area of ​​necrosis, timely and constant diagnosis of myocardial infarction is needed.

The table shows what the list of data on the work of the heart muscle looks like and a description of the stage of necrosis to them

Myocardial infarction on the ECG: decoding

The photo shows an ECG for myocardial infarction

To decipher the data received by the cardiographer, you need to know certain nuances. On the recorded sheet of paper, segments with and without teeth are clearly observed. They are indicated by Latin letters, which are responsible for the data taken from one of the sections of the heart muscle. These teeth are ECG indicators, criteria for myocardial infarction.

• Q - shows irritation of ventricular tissues;
• R - tops of the heart muscle;
• S - allows you to analyze the degree of irritation of the walls of the interventricular septum. The vector S is directed back to the vector R;
• T - "rest" of the ventricles of the heart muscle;
• ST - time (segment) of "rest".

To take data from different parts of the heart muscle, as a rule, 12 electrodes are used. For registration of a heart attack, electrodes installed on left side chest (fixed to leads V1-V6).

When "reading" the resulting diagram, doctors use the technique of calculating the length between oscillations. Having received the data, it is possible to analyze the rhythm of the heartbeat, while the teeth indicate the force with which the heart contracts. To determine violations, you need to use the following algorithm:

1. Analyze data on the rhythm and contractions of the heart muscle.
2. Calculate the length between oscillations.
3. Calculate electric axle hearts.
4. Study the complex of indications under the values ​​of Q, R, S.
5. Perform ST-segment analysis.

Attention! If there was an attack of myocardial infarction without ST segment elevation, then the reason for this could be ruptures of the formed fatty plaque in the blood vessel. This leads to active blood clotting with the formation of a blood clot.

Signs of myocardial infarction on the ECG

Myocardial infarction has manifestations of varying degrees of complexity. There are 4 types (stages) of myocardial infarction that can be traced on the patient's cardiogram.

Acute stage

Manifestations of the onset of necrosis can be understood by pain in the chest

The first stage can last up to three days, being the most acute in the entire course of the disease. In the initial stages of the first stage of myocardial infarction, necrosis is formed - a damaged area, which can be of two types: transmural and intramural myocardial infarction. The ECG during this period contains the following changes in the indications of the work of the heart:

1. The ST segment is elevated, forming a convex arc - elevation.
2. The ST segment coincides with the positive T wave - monophase.
3. Depending on the severity of necrosis, the R wave will decrease in height.

And reciprocal changes, respectively, consist in an increase in the R wave.

Acute stage

Varieties of stages of a heart attack: from the second, longer stages of the disease begin

This is followed by the second stage, which can last 2-3 weeks. There is a decrease in the focus of necrosis. At this time, ECG signs of myocardial infarction and ischemia appear due to dead cardiomyocytes in the acute period of myocardial infarction. On the ECG in the acute period, the following indications of electronic sensors are noted:

1. The ST segment is close to the isoline compared to the data obtained in the first stage, but it is still above it.
2. QS and QR pathologies are formed in trans- and non-transmural lesions of the heart muscle, respectively.
3. A negative symmetrical T wave is formed.

Reciprocal changes are opposite: the T wave increases in height, and the ST segment rises to the isoline.

Subacute stage of myocardial infarction

The duration of the third stage in the sequence is even longer - up to 7-8 weeks. At this time, the disease begins to stabilize, necrosis is observed in true size. In this period, the indications of a heart attack on the ECG are as follows:

1. The ST segment aligns with the isoline.
2. QR and QS pathologies persist.
3. The T wave begins to deepen.

Scarring

The last stage of myocardial infarction, starting from the 5th week. The stage received a similar name due to the fact that a scar begins to form at the site of necrosis. This scarring area has no electrical and physiological activity. Signs of scarring are displayed on the ECG by the following signs:

1. Pathological Q wave available. It is worth remembering that with trans- and non-transmural ailments, pathologies of the QS and QR complexes are observed, respectively.
2. The ST segment is aligned with the isoline.
3. The T wave is positive, depressed, or flattened (flattened).

During this period, the pathological teeth may completely disappear and the ECG will not be able to detect a heart attack that has occurred.

How to recognize the exact site of necrosis

Localization will show by ECG

To identify the localization of necrosis (myocardial infarction) on the ECG, it is not necessary to conduct additional examinations. An ECG in a heart attack can provide enough information to identify the suspected area. In this case, the cardiogram of the heart will be slightly different.

The following factors also affect the readings of electrical equipment:

1. time of onset of the disease;
2. the depth of the lesion;
3. reversibility of necrosis;
4. localization of myocardial infarction;
5. associated violations.

Classifying a heart attack by localization, the following possible cases of the course of the disease can be distinguished:

1. infarction of the anterior wall;
2. back wall;
3. septal;
4. side;
5. basal.

The definition and classification of the affected area helps to assess the complexity and identify complications of the disease. For example, if the lesion has affected the upper part of the heart muscle, then it will not spread, since it is isolated. The defeat of the right ventricle is very rare, moreover, it has its own characteristics in the treatment.

For example, an anterior septal infarction on an ECG looks like this:

1. Spike T waves in leads 3-4.
2. Q - 1-3.
3. The ST segment has a rise in segments 1-3.

WHO classification of myocardial infarction

Methods and duration of treatment depend on the degree of complexity of the disease.

To classify myocardial infarction, the WHO classification is used. What distinguishes these norms is that they are used only for the classification of large-focal lesions, therefore, according to these norms, mild forms of the course of the disease are not considered.

According to this classification, the following types of damage are distinguished:

• Spontaneous. Occurs due to the destruction of cholesterol plaques, tissue erosion.
• Secondary. Oxygen deficiency caused by overlap blood vessel thrombus or spasm.
• Sudden coronary death. With this heart attack, there is a complete violation of the contractility of the heart with its stop.
• Percutaneous coronary intervention. The reason becomes surgical intervention leading to damage to blood vessels or the heart muscle.
• stent thrombosis.
• Complication of aortic bypass surgery.

Using this qualification, it is possible to determine the degree of necrosis and the causes that gave rise to it. As a rule, it is used for complex forms of infarction, since the lungs can be determined by the timing of the lesion and localization.

Classification by term

To identify the complexity of the lesion, it is necessary to correctly establish the timing of the course of the disease. As a rule, this is primarily determined from the patient's history, which contains a call card, and after an initial examination. But they only allow you to provide first aid and perform procedures until the diagnosis is fully revealed.

Stages of a heart attack by time:

1. Premonitory. Pre-infarction state, when symptoms begin to appear. The duration can be up to a month.
2. Sharpest. In this period, the disease proceeds with the formation of necrosis. Duration about 2 hours.
3. Spicy. Necrosis develops within 10 days, which can occur with complete necrosis of some areas.
4. Subacute. Until the fifth week from the onset of the disease. At this stage of the course of the disease, necrotic areas begin to scar.
5. The post-infarction period proceeds with the adaptation of the heart muscles to new conditions of functioning and with the complete formation of the scar. It may take up to six months.

After the rehabilitation period has passed, the ECG changes disappear, signs of chronic ischemia remain.