Displacement of the heart is dangerous. Video: EOS in the course “Everyone can do an ECG.” Mechanism of electrical processes

The electrical axis of the heart (EOS) is one of the main parameters of the electrocardiogram. This term actively used both in cardiology and in functional diagnostics, reflecting the processes occurring in the most important organ human body.

Position electrical axis the heart shows the specialist what exactly is happening in the heart muscle every minute. This parameter is the sum of all bioelectrical changes observed in the organ. When taking an ECG, each electrode of the system registers excitation passing at a strictly defined point. If you transfer these values ​​to a conventional three-dimensional coordinate system, you can understand how the electrical axis of the heart is located and calculate its angle relative to the organ itself.

Before discussing the direction of the electrical axis, you should understand what the conduction system of the heart is. It is this structure that is responsible for the passage of impulses through the myocardium. The conduction system of the heart is atypical muscle fibers that connect various areas organ. It starts with sinus node, located between the mouths of the vena cava. Next, the impulse is transmitted to the atrioventricular node, located in the lower part of the right atrium. The next to take up the baton is the His bundle, which quickly diverges into two legs - left and right. In the ventricle, the branches of the His bundle immediately become Purkinje fibers, which penetrate the entire cardiac muscle.

EOS location options

Cardiac ischemia;

Chronic heart failure;

Cardiomyopathies of various origins;

Congenital defects.

Why is changing EOS dangerous?

The normal EOS value is considered to be the range from +30 to +70°.

Horizontal (from 0 to +30°) and vertical (from +70 to +90°) positions of the heart axis are acceptable values and do not talk about the development of any pathology.

Deviations of the EOS to the left or right may indicate various violations in the conduction system of the heart and require specialist consultation.

A change in EOS detected on a cardiogram cannot be made as a diagnosis, but is a reason to visit a cardiologist.

The heart is amazing organ, ensuring the functioning of all systems of the human body. Any changes that occur in it inevitably affect the functioning of the whole organism. Regular examinations by a therapist and an ECG will allow timely detection of serious illnesses and avoid the development of any complications in this area.

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The electrical axis of the heart is a concept that reflects the total vector of the electrodynamic force of the heart, or its electrical activity, and practically coincides with the anatomical axis. Normally, this organ has a cone-shaped shape, with its narrow end directed downwards, forward and to the left, and the electrical axis has a half vertical position, that is, it is also directed down and to the left, and when projected onto a coordinate system, it can be in the range from +0 to +90 0.

An ECG conclusion is considered normal if it indicates any of the following positions of the heart axis: not deviated, semi-vertical, semi-horizontal, vertical or horizontal position. The axis is closer to the vertical position in thin people tall people asthenic physique, and to the horizontal - in strong stocky persons of hypersthenic physique.

Electric axis position range is normal

For example, in the conclusion of an ECG, the patient may see the following phrase: “sinus rhythm, EOS is not deviated...”, or “the axis of the heart is in a vertical position,” this means that the heart is working correctly.

In the case of heart disease, the electrical axis of the heart, along with the heart rhythm, is one of the first ECG criteria that the doctor pays attention to, and when interpreting the ECG, the attending physician must determine the direction of the electrical axis.

Deviations from the norm are deviation of the axis to the left and sharply to the left, to the right and sharply to the right, as well as the presence of non-sinus heart rate.

How to determine the position of the electrical axis

Determination of the position of the heart axis is carried out by a doctor functional diagnostics, deciphering the ECG, using special tables and diagrams, according to the angle α (“alpha”).

The second way to determine the position of the electrical axis is to compare the QRS complexes responsible for the excitation and contraction of the ventricles. So, if the R wave has a greater amplitude in the I chest lead than in the III, then there is a levogram, or deviation of the axis to the left. If there is more in III than in I, then it is a legal grammar. Normally, the R wave is higher in lead II.

Reasons for deviations from the norm

Axial deviation to the right or left is not considered an independent disease, but it can indicate diseases that lead to disruption of the heart.

Deviation of the heart axis to the left often develops with left ventricular hypertrophy

Deviation of the heart axis to the left can occur normally in healthy individuals who are professionally involved in sports, but more often develops with left ventricular hypertrophy. This is an increase in the mass of the heart muscle with a violation of its contraction and relaxation, necessary for the normal functioning of the entire heart. Hypertrophy can be caused by the following diseases:

• cardiomyopathy (increase in myocardial mass or dilation of the heart chambers) caused by anemia, disorders hormonal levels in organism, coronary disease heart, post-infarction cardiosclerosis. changes in the structure of the myocardium after myocarditis (inflammatory process in cardiac tissue);
• long-term arterial hypertension, especially with constantly high blood pressure numbers;
• acquired heart defects, in particular stenosis (narrowing) or insufficiency (incomplete closure) aortic valve, leading to disruption of intracardiac blood flow, and, consequently, increased load to the left ventricle;
• congenital heart defects often cause a deviation of the electrical axis to the left in a child;
• conduction disturbance along the left bundle branch - complete or not complete blockade, leading to impaired contractility of the left ventricle, while the axis is deviated, and the rhythm remains sinus;
• atrial fibrillation, then the ECG is characterized not only by axis deviation, but also by the presence of non-sinus rhythm.

Deviation of the heart axis to the right is a normal variant when conducting an ECG in a newborn child, and in this case a sharp deviation of the axis may occur.

In adults, such a deviation is usually a sign of right ventricular hypertrophy, which develops in the following diseases:

• diseases bronchopulmonary system– long-term bronchial asthma, severe obstructive bronchitis, pulmonary emphysema, leading to increased blood pressure in the pulmonary capillaries and increasing the load on the right ventricle;
• heart defects with damage to the tricuspid (three-leaf) valve and the valve of the pulmonary artery, which arises from the right ventricle.

The greater the degree of ventricular hypertrophy, the more the electrical axis is deflected, respectively, sharply to the left and sharply to the right.

Symptoms

The electrical axis of the heart itself does not cause any symptoms in the patient. Impaired health appears in the patient if myocardial hypertrophy leads to severe hemodynamic disturbances and heart failure.

The disease is characterized by pain in the heart area

Signs of diseases accompanied by deviation of the heart axis to the left or right include headaches, pain in the heart area, swelling lower limbs and on the face, shortness of breath, asthma attacks, etc.

If any unpleasant cardiac symptoms appear, you should consult a doctor for conducting an ECG, and if an abnormal position of the electrical axis is detected on the cardiogram, it is necessary to perform further examination to establish the cause of this condition, especially if it is detected in a child.

Diagnostics

To determine the cause of an ECG deviation of the heart axis to the left or right, a cardiologist or therapist may prescribe additional methods research:

1. Ultrasound of the heart is the most informative method, allowing you to assess anatomical changes and identify ventricular hypertrophy, as well as determine the degree of disruption contractile function. This method is especially important for examining a newborn baby for congenital pathology hearts.
2. ECG with exercise (walking on a treadmill - treadmill test, bicycle ergometry) can detect myocardial ischemia, which may be the cause of deviations in the electrical axis.
3. Daily ECG monitoring in the event that not only an axis deviation is detected, but also the presence of a rhythm not from the sinus node, that is, rhythm disturbances occur.
4. Radiography chest- with severe myocardial hypertrophy, an expansion of the cardiac shadow is characteristic.
5. Coronary angiography (CAG) – performed to clarify the nature of the lesions coronary arteries with ischemic disease a.

Treatment

Direct deviation of the electrical axis does not require treatment, since it is not a disease, but a criterion by which it can be assumed that the patient has one or another cardiac pathology. If, after further examination, some disease is identified, it is necessary to begin treatment as soon as possible.

In conclusion, it should be noted that if the patient sees in the ECG conclusion a phrase that the electrical axis of the heart is not in a normal position, this should alert him and prompt him to consult a doctor to find out the cause of such an ECG sign, even if there are no symptoms does not arise.

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When the EOS is in a vertical position, the S wave is most pronounced in leads I and aVL. ECG in children aged 7–15 years. Characterized by respiratory arrhythmia, heart rate 65-90 per minute. The position of the EOS is normal or vertical.

Regular sinus rhythm - this phrase means an absolutely normal heart rhythm, which is generated in the sinus node (the main source of cardiac electrical potentials).

Left ventricular hypertrophy (LVH) is a thickening of the wall and/or enlargement of the left ventricle of the heart. All five position options (normal, horizontal, semi-horizontal, vertical and semi-vertical) occur in healthy people and are not pathological.

What does the vertical position of the heart axis on an ECG mean?

The definition of “rotation of the electrical axis of the heart around an axis” may well be found in descriptions of electrocardiograms and is not something dangerous.

The situation should be alarming when, with a pre-existing position of the EOS, its sharp deviation on the ECG occurs. In this case, the deviation most likely indicates the occurrence of a blockade. 6.1. P wave. Analysis of the P wave involves determining its amplitude, width (duration), shape, direction and degree of severity in various leads.

The always negative wave vector P is projected onto the positive parts of most leads (but not all!).

6.4.2. The degree of severity of the Q wave in various leads.

Methods for determining the position of the EOS.

To put it simply, an ECG is a dynamic recording electric charge, thanks to which our heart works (that is, contracts). The designations of these graphs (they are also called leads) - I, II, III, aVR, aVL, aVF, V1-V6 - can be seen on the electrocardiogram.

ECG is a completely painless and safe research, it is performed on adults, children and even pregnant women.

Heart rate is not a disease or a diagnosis, but just an abbreviation for “heart rate,” which refers to the number of contractions of the heart muscle per minute. When the heart rate increases above 91 beats/min, they speak of tachycardia; if the heart rate is 59 beats/min or less, this is a sign of bradycardia.

Electrical axis of the heart (EOS): essence, norm of position and violations

Thin people usually have a vertical position of the EOS, while thick people and obese people have a horizontal position. Respiratory arrhythmia is associated with the act of breathing, is normal and does not require treatment.

Requires compulsory treatment. Atrial flutter - this type of arrhythmia is very similar to atrial fibrillation. Sometimes polytopic extrasystoles occur - that is, the impulses that cause them come from various parts of the heart.

Extrasystoles can be called the most common ECG finding; moreover, not all extrasystoles are a sign of the disease. In this case, treatment is necessary. Atrioventricular block, A-V (A-V) block - a violation of the conduction of impulses from the atria to the ventricles of the heart.

Block of the branches (left, right, left and right) of the His bundle (RBBB, LBBB), complete, incomplete, is a violation of the conduction of an impulse through the conduction system in the thickness of the ventricular myocardium.

The most common reasons hypertrophies are arterial hypertension, heart defects and hypertrophic cardiomyopathy. In some cases, next to the conclusion about the presence of hypertrophy, the doctor indicates “with overload” or “with signs of overload.”

Variants of the position of the electrical axis of the heart in healthy people

Cicatricial changes, scars are signs of a myocardial infarction once suffered. In such a situation, the doctor prescribes treatment aimed at preventing a recurrent heart attack and eliminating the cause of circulatory problems in the heart muscle (atherosclerosis).

Timely detection and treatment of this pathology is necessary. Normal ECG in children aged 1 – 12 months. Typically, heart rate fluctuations depend on the child’s behavior (increased frequency when crying, restlessness). At the same time, over the past 20 years there has been a clear trend towards an increase in the prevalence of this pathology.

When can the position of the EOS indicate heart disease?

The direction of the electrical axis of the heart shows the total magnitude of bioelectric changes occurring in the heart muscle with each contraction. The heart is a three-dimensional organ, and in order to calculate the direction of the EOS, cardiologists represent the chest as a coordinate system.

If you project the electrodes onto a conventional coordinate system, you can also calculate the angle of the electrical axis, which will be located where the electrical processes are strongest. The conduction system of the heart consists of sections of the heart muscle consisting of so-called atypical muscle fibers.

Normal ECG readings

Myocardial contraction begins with the appearance of an electrical impulse in the sinus node (which is why the correct rhythm healthy heart called sinus). The myocardial conduction system is a powerful source of electrical impulses, which means that electrical changes that precede cardiac contraction occur in it first of all in the heart.

Rotations of the heart around the longitudinal axis help determine the position of the organ in space and, in some cases, are an additional parameter in diagnosing diseases. The position of the EOS itself is not a diagnosis.

These defects can be either congenital or acquired. The most common acquired heart defects are a consequence of rheumatic fever.

In this case, a consultation with a highly qualified sports doctor is necessary to decide on the possibility of continuing to play sports.

A shift in the electrical axis of the heart to the right may indicate right ventricular hypertrophy (RVH). Blood from the right ventricle enters the lungs, where it is enriched with oxygen.

As in the case of the left ventricle, RVH is caused by coronary heart disease, chronic heart failure and cardiomyopathies.

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Department of Medical Cybernetics and Informatics RNRMU named after N.I. Pirogov

Work on the section Using the capabilities of a word processor to process and present medical information

The work was carried out by a student of group 243 Mikhailovskaya Ekaterina Aleksandrovna

MOSCOW 2014

General information about ECG

An ECG is a recording of the potential difference between two electrodes located on the surface of the body. The combination of two such electrodes is called an electrocardiographic lead, and an imaginary straight line connecting the two electrodes is called the axis of this lead. Leads can be bipolar or unipolar. In bipolar leads, the potential changes under both electrodes. In unipolar leads, the potential changes under one (active) electrode, but not under the second (indifferent) electrode.

For ECG registration an indifferent electrode is obtained by combining together the electrodes from the left hand, right hand and left leg; This is the so-called zero electrode (combined electrode, central terminal).

ECG leads.

Typically 12 leads are used. They are combined into two groups:

six limb leads (their axes lie in the frontal plane)

six chest leads (axis - in the horizontal plane).

Limb leads.

The limb leads are divided into three bipolar (standard leads I, II and III) and three unipolar (enhanced leads aVR, aVL and aVF).

In standard leads, electrodes are applied as follows: I - left hand and right hand, II - left leg and right hand, III - left leg and left hand.

In amplified leads, the active electrode is placed: for lead aVR - on the right hand (R - right), for lead aVL - on the left hand (L - left), for lead aVF - on the left leg (F - foot). The letter “V” in the names of these leads means that they measure potential values ​​(Foliage) under active electrode, the letter “a” - that this potential is enhanced (Augmented).

Strengthening is achieved by excluding from the null electrode the electrode that is applied to the limb under study (for example, in lead aVF, the null electrode is the combined electrode from the right hand and left hand).

On right leg A grounding electrode is always applied.

Chest leads.

To obtain unipolar chest leads, electrodes are installed at the following points:

• fourth intercostal space along the right edge of the sternum,

• fourth intercostal space on the left edge of the sternum,

• between V2 and V4,

• fifth intercostal space along the left midclavicular line;

• at the same vertical level as V4, but, respectively, along the anterior and midaxillary line.

The indifferent electrode is the usual zero electrode.

The ECG in each lead is a projection of the total vector onto the axis of this lead. Thus, different leads allow us to look at the electrical processes in the heart from different angles. The twelve ECG leads together create a three-dimensional picture of the heart's electrical activity; in addition to them, additional leads are sometimes used. Thus, to diagnose right ventricular infarction, right chest leads V3R, V4R and others are used. Esophageal leads allow us to detect changes in the electrical activity of the atria that are not visible on a conventional ECG.

For telemetric ECG monitoring, one is usually used, and for Holter monitoring, two modified leads are usually used.

Lead meaning

Why were so many leads invented? The EMF of the heart is the vector of the EMF of the heart in the three-dimensional world (length, width, height) taking into account time. On a flat ECG film we can see only 2-dimensional values, so the cardiograph records the projection of the EMF of the heart on one of the planes in time.

Body planes used in anatomy.

Each lead records its own projection of the cardiac EMF. The first 6 leads (3 standard and 3 enhanced from the limbs) reflect the EMF of the heart in the so-called frontal plane and allow you to calculate the electrical axis of the heart with an accuracy of 30° (180° / 6 leads = 30°). The missing 6 leads to form a circle (360°) are obtained by continuing the existing lead axes through the center to the second half of the circle.

6 chest leads reflect the EMF of the heart in the horizontal (transverse) plane (it divides the human body into upper and lower halves). This makes it possible to clarify the localization of the pathological focus (for example, myocardial infarction): interventricular septum, apex of the heart, lateral parts of the left ventricle, etc.

 Electrical axis of the heart (EOS)

If we draw a circle and draw lines through its center corresponding to the directions of the three standard and three enhanced limb leads, we obtain a 6-axis coordinate system. When recording an ECG in these 6 leads, 6 projections of the total EMF of the heart are recorded, from which the location of the pathological focus and the electrical axis of the heart can be assessed.

The electrical axis of the heart is the projection of the total electrical vector of the ECG QRS complex (it reflects the excitation of the ventricles of the heart) onto the frontal plane. Quantitatively, the electrical axis of the heart is expressed by the angle α between the axis itself and the positive (right) half of the axis I of the standard lead, located horizontally.

The rules for determining the position of the EOS in the frontal plane are as follows: the electrical axis of the heart coincides with the one of the first 6 leads in which the highest positive teeth are recorded, and is perpendicular to the lead in which the size of the positive teeth is equal to the size of the negative teeth. Two examples of determining the electrical axis of the heart are given at the end of the article.

Variants of the position of the electrical axis of the heart:

normal: 30° > α< 69°,

vertical: 70° > α< 90°,

horizontal: 0° > α< 29°,

sharp axis deviation to the right: 91° > α< ±180°,

sharp axis deviation to the left: 0° > α< −90°.

Normally, the electrical axis of the heart approximately corresponds to its anatomical axis (y skinny people is directed more vertically from the average values, and in obese people - more horizontally). For example, with hypertrophy (growth) of the right ventricle, the heart axis deviates to the right. With conduction disturbances, the electrical axis of the heart may deviate sharply to the left or right, which in itself is diagnostic sign. For example, with a complete block of the anterior branch of the left bundle branch, a sharp deviation of the electrical axis of the heart to the left (α ≤ −30°) is observed, and a sharp deviation of the posterior branch to the right (α ≥ +120°).

Complete block of the anterior branch of the left bundle branch. The EOS is sharply deviated to the left (α ≅− 30°), because the highest positive waves are visible in aVL, and the equality of the waves is noted in lead II, which is perpendicular to aVL.

Complete block of the posterior branch of the left bundle branch. The EOS is sharply deviated to the right (α ≅+120°), because The tallest positive waves are seen in lead III, and the equality of the waves is noted in lead aVR, which is perpendicular to III.

Waves in ECG

Any ECG consists of waves, segments and intervals.

Waves are convex and concave areas on an electrocardiogram. The following waves are distinguished on the ECG:

P (atrial contraction),

Q, R, S (all 3 teeth characterize ventricular contraction),

T (ventricular relaxation),

U (non-permanent wave, rarely recorded).

A segment on an ECG is a segment of a straight line (isoline) between two adjacent teeth. Highest value have segments P-Q and S-T. For example, P-Q segment is formed due to a delay in the conduction of excitation in the atrioventricular (AV) node.

The interval consists of a tooth (a complex of teeth) and a segment. Thus, interval = tooth + segment. The most important are the P-Q and Q-T intervals.

P-Wines

Normally, the excitation wave propagates from the sinus node through the myocardium of the right and then the left atrium, and the total vector of atrial depolarization is directed predominantly down and to the left. Because it faces the positive pole of lead II and the negative pole of lead aVR, the P wave is normally positive in lead II and negative in lead aVR.

With retrograde excitation of the atria (inferior atrial or AV nodal rhythm), the opposite picture is observed.

QRS-Complex

Normally, the excitation wave quickly spreads through the ventricles. This process can be divided into two phases, each of which is characterized by a certain predominant direction of the total vector. Depolarization occurs first interventricular septum from left to right (vector 1), and then - depolarization of the left and right ventricles (vector 2). Since the depolarization wave covers the thick left ventricle for a longer time than the thin right ventricle, vector 2 is directed to the left and backward. In the right chest leads, this two-phase process is reflected by a small positive wave (septal r wave) and a deep S wave, and in the left chest leads (for example, in V6) - by a small negative wave (septal q wave) and a large R wave. In leads V2-V5, the amplitude of the R wave gradually increases, the S- wave decreases. The lead in which the amplitudes of the R and S waves are approximately equal (usually V3 or V4) is called the transition zone.

In healthy people, the shape of the QRS complex in the limb leads varies significantly depending on the position of the electrical axis of the heart (the predominant, or more precisely, the time-averaged direction of the total vector of ventricular depolarization in the frontal plane). The normal position of the electrical axis of the heart is from -30* to +100*; in all other cases, they speak of axis deviation to the left or right.

Deviation of the electrical axis of the heart to the left can be a normal variant, but is more often caused by left ventricular hypertrophy, blockade of the anterior branch of the left bundle branch, and inferior myocardial infarction.

Deviation of the electrical axis of the heart to the right also occurs normally (especially in children and young people), with right ventricular hypertrophy, infarction of the lateral wall of the left ventricle, dextrocardia, left-sided pneumothorax, and blockade of the posterior branch of the left bundle branch.

A false impression of electrical axis deviation can occur if the electrodes are applied incorrectly.

T-waves

Normally, the T wave is directed in the same direction as the QRS complex (concordant with the QRS complex). This means that the predominant direction of the ventricular repolarization vector is the same as the vector of their depolarization. Considering that depolarization and repolarization are opposite electrical processes, the unidirectionality of the T wave of the QRS complex can only be explained by the fact that repolarization moves in the direction opposite to the depolarization wave (that is, from the epicardial endocardium and from the apex to the base of the heart).

U-Prongs

The U wave is normally a small rounded wave (less than or equal to 0.1 mV) that follows the Ti wave and has the same direction. An increase in U wave amplitude is most often caused by medicines(quinidine, procainamide, disopyramide) and hypokalemia.

Tall U waves indicate increased risk pirouette tachycardia. Negative U waves in the precordial leads are always a pathological sign; it may serve as the first manifestation of myocardial ischemia.

ECG analysis

General scheme ECG interpretation

ECG interpretation

Checking the correct ECG registration

At the beginning of each ECG tape there must be a calibration signal - the so-called reference millivolt. To do this, at the beginning of the recording, a standard voltage of 1 millivolt is applied, which should display a deviation of 10 mm on the tape. Without a calibration signal, the ECG recording is considered incorrect. Normally, according to at least in one of the standard or reinforced limb leads, the amplitude should exceed 5 mm, and in the chest leads -8 mm. If the amplitude is lower, this is called reduced ECG voltage, which occurs in some pathological conditions.

Heart rate and conduction analysis:

assessment of heart rate regularity

Rhythm regularity is assessed by R-R intervals. If the teeth are at an equal distance from each other, the rhythm is called regular, or correct. The spread of the duration of individual R-R intervals is allowed no more than ± 10% of their average duration. If the rhythm is sinus, it is usually regular.

heart rate counting (HR)

The ECG film has large squares printed on it, each of which contains 25 small squares (5 vertical x 5 horizontal). To quickly calculate heart rate with the correct rhythm, count the number of large squares between two adjacent R-R waves.

At a belt speed of 50 mm/s: HR = 600 / (number of large squares). At a belt speed of 25 mm/s: HR = 300/(number of large squares).

On the overlying ECG interval R-R is equal to approximately 4.8 large cells, which at a speed of 25 mm/s gives 300 / 4.8 = 62.5 beats/min.

At a speed of 25 mm/s, each small cell is equal to 0.04 s, and at a speed of 50 mm/s -0.02 s. This is used to determine the duration of the teeth and intervals.

If the rhythm is incorrect, the maximum and minimum heart rate is usually calculated according to the duration of the smallest and largest R-R interval respectively.

determination of the excitation source

In other words, they are looking for where the pacemaker is located, which causes contractions of the atria and ventricles. Sometimes this is one of the most difficult stages, because various disorders of excitability and conduction can be very intricately combined, which can lead to misdiagnosis and improper treatment. To correctly determine the source of excitation on an ECG, you need to have a good knowledge of the conduction system of the heart.

Determination of the electrical axis of the heart.

In the first part of the ECG series, it was explained what the electrical axis of the heart is and how it is determined in the frontal plane.

Atrial P wave analysis.

Normally, in leads I, II, aVF, V2 - V6, the P wave is always positive. In leads III, aVL, V1, the P wave can be positive or biphasic (part of the wave is positive, part is negative). In lead aVR, the P wave is always negative.

Normally, the duration of the P wave does not exceed 0.1 s, and its amplitude is 1.5 - 2.5 mm.

Pathological deviations of the P wave:

Pointed tall P waves normal duration in leads II, III, aVF are characteristic of hypertrophy of the right atrium, for example, with “pulmonary heart”.

Split with 2 apexes, widened P wave in leads I, aVL, V5, V6 is characteristic of left atrium hypertrophy, for example, with mitral valve defects.

P-Q interval: normal 0.12-0.20 s.

An increase in this interval occurs when the conduction of impulses through the atrioventricular node is impaired (atrioventricular block, AV block).

There are 3 degrees of AV block:

I degree - the P-Q interval is increased, but each P wave corresponds to its own QRS complex (there is no loss of complexes).

II degree - QRS complexes partially fall out, i.e. Not all P waves have their own QRS complex.

III degree - complete blockade of conduction in the AV node. The atria and ventricles contract at their own rhythm, independently of each other. Those. idioventricular rhythm occurs.

Analysis of the ventricular QRST complex:

analysis of the QRS complex.

The maximum duration of the ventricular complex is 0.07-0.09 s (up to 0.10 s). The duration increases with any bundle branch block.

Normally, the Q wave can be recorded in all standard and enhanced limb leads, as well as in V4-V6. The amplitude of the Q wave normally does not exceed 1/4 of the height of the R wave, and the duration is 0.03 s. In lead aVR, there is normally a deep and wide Q wave and even a QS complex.

The R wave, like the Q wave, can be recorded in all standard and enhanced limb leads. From V1 to V4, the amplitude increases (while the rV1 wave may be absent), and then decreases in V5 and V6.

The S wave can have very different amplitudes, but usually no more than 20 mm. The S wave decreases from V1 to V4, and may even be absent in V5-V6. In lead V3 (or between V2 - V4), a “transition zone” is usually recorded (equality of the R and S waves).

RS-T segment analysis

The S-T segment (RS-T) is a segment from the end of the QRS complex to the beginning of the T wave. The S-T segment is especially carefully analyzed in case of coronary artery disease, since it reflects the lack of oxygen (ischemia) in the myocardium.

Fine S-T segment located in the limb leads on the isoline (± 0.5 mm). In leads V1-V3, the S-T segment may shift upward (no more than 2 mm), and in leads V4-V6 - downward (no more than 0.5 mm).

The transition point of the QRS complex to the S-T segment is called point j (from the word junction - connection). The degree of deviation of point j from the isoline is used, for example, to diagnose myocardial ischemia.

T wave analysis.

The T wave reflects the process of repolarization of the ventricular myocardium. In most leads where a high R is recorded, the T wave is also positive. Normally, the T wave is always positive in I, II, aVF, V2-V6, with TI > TIII, and TV6 > TV1. In aVR the T wave is always negative.

Q-T interval analysis.

The Q-T interval is called electrical ventricular systole, because at this time all parts of the ventricles of the heart are excited. Sometimes after the T wave a small U wave is recorded, which is formed due to short-term increased excitability of the ventricular myocardium after their repolarization.

Electrocardiographic report.

Should include:

Source of rhythm (sinus or not).

Regularity of rhythm (correct or not). Usually sinus rhythm is correct, although respiratory arrhythmia is possible.

Position of the electrical axis of the heart.

Presence of 4 syndromes:

• rhythm disturbance

  conduction disturbance

  hypertrophy and/or overload of the ventricles and atria

  myocardial damage (ischemia, dystrophy, necrosis, scars)

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Axis location

In a healthy person, the left ventricle has a larger mass than the right.

This means that stronger electrical processes occur in the left ventricle, and accordingly the electrical axis is directed there.

If we denote this in degrees, then the LV is in the region of 30-700 with a value of +. This is considered the standard, but it should be said that not everyone has this axis arrangement.

There may be a deviation greater than 0-900 with a value of +, since it is necessary to take into account the individual characteristics of each person’s body.

The doctor may make the following conclusion:

• no deviations;
• semi-vertical position;
• semi-horizontal position.

All these conclusions are the norm.

Concerning individual characteristics, then they note that in people tall and a thin build, the EOS is in a semi-vertical position, and in people who are shorter and have a stocky build, the EOS is in a semi-horizontal position.

The pathological condition looks like a sharp deviation to the left or right.

Reasons for rejection

When the EOS deviates sharply to the left, this may mean that there are certain diseases, namely LV hypertrophy.

In this condition, the cavity stretches and increases in size. Sometimes this occurs due to overload, but it can also be a consequence of a disease.

Diseases that cause hypertrophy are:

In addition to hypertrophy, the main causes of axis deviation to the left are conduction disorders inside the ventricles and during blockades of various types.

Quite often, with such a deviation, blockade of the left leg of His, namely its anterior branch, is diagnosed.

As for the pathological deviation of the heart axis sharply to the right, this may mean that there is RV hypertrophy.

This pathology can be caused by the following diseases:

As well as diseases characteristic of LV hypertrophy:

• cardiac ischemia;
• chronic heart failure;
• cardiomyopathy;
• complete blockade of the left leg of His (posterior branch).

When the electrical axis of the heart is sharply deviated to the right in a newborn, this is considered normal.

We can conclude that the main cause of pathological displacement to the left or right is ventricular hypertrophy.

And the greater the degree of this pathology, the more EOS is rejected. A change in the axis is simply an ECG sign of some disease.

It is important to carry out timely identification of these indications and diseases.

Deviation of the heart axis does not cause any symptoms; symptoms manifest themselves from hypertrophy, which disrupts the hemodynamics of the heart. The main symptoms are headaches, chest pain, swelling of the limbs and face, suffocation and shortness of breath.

If cardiac symptoms occur, you should immediately undergo electrocardiography.

Determination of ECG signs

Legal form. This is the position at which the axis is within the range of 70-900.

On the ECG this is expressed as tall R waves in the QRS complex. In this case, the R wave in lead III exceeds the wave in lead II. In lead I there is an RS complex, in which S has a greater depth than the height of R.

Levogram. In this case, the position of the alpha angle is within the range of 0-500. The ECG shows that in standard lead I the QRS complex is expressed as R-type, and in lead III its form is S-type. The S wave has a depth greater than the height R.

With blockade of the posterior branch of the left leg of His, the alpha angle has a value greater than 900. On the ECG, the duration of the QRS complex may be slightly increased. There is a deep S wave (aVL, V6) and a high R wave (III, aVF).

With blockade of the anterior branch of the left leg of His, the values ​​will be from -300 or more. On ECG signs These are the late R wave (lead aVR). Leads V1 and V2 may have a small r wave. In this case, the QRS complex is not expanded, and the amplitude of its waves is not changed.

Blockade of the anterior and posterior branches of the left leg of His (complete block) - in this case, the electrical axis is sharply deviated to the left and can be located horizontally. On the ECG in the QRS complex (leads I, aVL, V5, V6), the R wave is widened and its apex is jagged. Near the high R wave there is a negative T wave.

It should be concluded that the electrical axis of the heart can be moderately deviated. If the deviation is sharp, then this may mean the presence of serious cardiac diseases.

Determination of these diseases begins with an ECG, and then methods such as echocardiography, radiography, and coronary angiography are prescribed. ECG can also be performed with stress and daily monitoring according to Holter.

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How is an electrocardiogram taken?

ECG recording is performed in a special room, maximally shielded from various electrical interference. The patient sits comfortably on the couch with a pillow under his head. To take an ECG, electrodes are applied (4 on the limbs and 6 on the chest). An electrocardiogram is recorded during quiet breathing. In this case, the frequency and regularity of heart contractions, the position of the electrical axis of the heart and some other parameters are recorded. This simple method allows you to determine whether there are abnormalities in the functioning of the organ, and, if necessary, refer the patient for a consultation with a cardiologist.

What influences the location of the EOS?

Before discussing the direction of the electrical axis, you should understand what the conduction system of the heart is. It is this structure that is responsible for the passage of impulses through the myocardium. The conduction system of the heart is atypical muscle fibers that connect different parts of the organ. It begins with the sinus node, located between the mouths of the vena cava. Next, the impulse is transmitted to the atrioventricular node, located in the lower part of the right atrium. The next to take the baton is the His bundle, which quickly diverges into two legs - left and right. In the ventricle, the branches of the His bundle immediately become Purkinje fibers, which penetrate the entire cardiac muscle.

An impulse entering the heart cannot escape the myocardial conduction system. This is a complex structure with fine settings, sensitively responding to the slightest changes in the body. In case of any disturbances in the conduction system, the electrical axis of the heart can change its position, which will be immediately recorded on the electrocardiogram.

EOS location options

As you know, the human heart consists of two atria and two ventricles. Two circles of blood circulation (large and small) ensure the normal functioning of all organs and systems. Normally, the mass of the myocardium of the left ventricle is slightly greater than that of the right. It turns out that all impulses passing through the left ventricle will be somewhat stronger, and the electrical axis of the heart will be oriented specifically towards it.

If you mentally transfer the position of the organ to a three-dimensional coordinate system, it will become clear that the EOS will be located at an angle from +30 to +70 degrees. Most often, these are the values ​​recorded on the ECG. The electrical axis of the heart can also be located in the range from 0 to +90 degrees, and this, too, according to cardiologists, is the norm. Why do such differences exist?

Normal location of the electrical axis of the heart

There are three main provisions of the EOS. The range from +30 to +70° is considered normal. This option occurs in the vast majority of patients who visit a cardiologist. The vertical electrical axis of the heart is found in thin, asthenic people. In this case, the angle values ​​will range from +70 to +90°. The horizontal electrical axis of the heart is found in short, tightly built patients. On their card, the doctor will mark the EOS angle from 0 to +30°. Each of these options is normal and does not require any correction.

Pathological location of the electrical axis of the heart

A condition in which the electrical axis of the heart is deviated is not a diagnosis in itself. However, such changes in the electrocardiogram may indicate various disorders in the functioning of the important body. TO major changes The following diseases affect the functioning of the conduction system:

Cardiac ischemia;

Chronic heart failure;

Cardiomyopathies of various origins;

Congenital defects.

Knowing about these pathologies, the cardiologist will be able to notice the problem in time and refer the patient for inpatient treatment. In some cases, when EOS deviation is registered, the patient requires emergency care in intensive care.

Deviation of the electrical axis of the heart to the left

Most often, such changes in the ECG are observed with enlargement of the left ventricle. This usually occurs with the progression of heart failure, when the organ simply cannot fully perform its function. It is possible that such a condition will develop when arterial hypertension, accompanied by pathology of large vessels and increased blood viscosity. In all these conditions, the left ventricle is forced to work hard. Its walls thicken, leading to inevitable disruption of the impulse through the myocardium.

Deviation of the electrical axis of the heart to the left also occurs with narrowing of the aortic mouth. In this case, stenosis of the lumen of the valve located at the exit from the left ventricle occurs. This condition is accompanied by a disruption of normal blood flow. Part of it is retained in the cavity of the left ventricle, causing it to stretch and, as a result, thickening of its walls. All this causes a natural change in EOS as a result of improper conduction of the impulse through the myocardium.

Deviation of the electrical axis of the heart to the right

This condition clearly indicates right ventricular hypertrophy. Similar changes develop in certain respiratory diseases (for example, bronchial asthma or chronic obstructive pulmonary disease). Some birth defects hearts can also cause enlargement of the right ventricle. First of all, it is worth noting pulmonary artery stenosis. In some situations, tricuspid valve insufficiency can also lead to a similar pathology.

Why is changing EOS dangerous?

Most often, deviations of the electrical axis of the heart are associated with hypertrophy of one or another ventricle. This condition is a sign of long-standing chronic process and, as a rule, does not require emergency assistance cardiologist. The real danger is the change in the electrical axis due to His bundle block. In this case, the conduction of impulses through the myocardium is disrupted, which means there is a risk of sudden cardiac arrest. This situation requires urgent intervention cardiologist and treatment in a specialized hospital.

With the development of this pathology, the EOS can be deviated both to the left and to the right, depending on the localization of the process. The blockade may be caused by myocardial infarction, infectious lesion heart muscle, as well as taking certain medications. A regular electrocardiogram allows you to quickly make a diagnosis, which means it allows the doctor to prescribe treatment taking into account all important factors. IN severe cases It may be necessary to install a pacemaker (pacemaker), which will send impulses directly to the heart muscle and thereby provide normal work organ.

What to do if the EOS is changed?

First of all, it is worth considering that the deviation of the heart axis itself is not the basis for making a particular diagnosis. The position of the EOS can only give impetus to a more careful examination of the patient. For any changes in the electrocardiogram, you cannot do without consulting a cardiologist. An experienced doctor will be able to recognize normal and pathological conditions, and, if necessary, prescribe additional examination. This may include echocardioscopy for targeted study of the condition of the atria and ventricles, blood pressure monitoring and other techniques. In some cases, consultation with related specialists is required to decide on further management of the patient.

To summarize, several important points should be highlighted:

The normal EOS value is considered to be the range from +30 to +70°.

Horizontal (from 0 to +30°) and vertical (from +70 to +90°) positions of the heart axis are acceptable values ​​and do not indicate the development of any pathology.

Deviations of the EOS to the left or to the right may indicate various disorders in the conduction system of the heart and require consultation with a specialist.

A change in EOS detected on a cardiogram cannot be made as a diagnosis, but is a reason to visit a cardiologist.

The heart is an amazing organ that ensures the functioning of all systems of the human body. Any changes that occur in it inevitably affect the functioning of the whole organism. Regular examinations by a therapist and an ECG will allow timely detection of serious diseases and avoid the development of any complications in this area.

The configuration of the QRS complex on the ECG depends on many factors, including the spatial position of the resulting vectors of ventricular depolarization and repolarization in relation to the axes of the electrocardiographic leads. This necessitates the determination of the position of the electrical axis of the heart (EOS) when analyzing the ECG.

EOS should be understood as the resulting vector of ventricular depolarization . An angle is formed between the direction of the vector and the first standard lead, which is called angle α . By the magnitude of the angle α one can judge the position of the electrical axis of the heart.

For adults over 18 years of age, the following provisions of the EOS are distinguished:

1. Normal position– angle α from -29° to +89°.

2. Deviation to the left– angle α -30° or less:

2.1. - moderate deviation to the left – angle α from-30° to -44°;

2.2. - pronounced deviation to the left – angle α from -45° to -90°.

3. Deviation to the right– angle α from +90 or more

3.1. - moderate deviation to the right – angle α from +90° to +120°;

3.2. - pronounced deviation to the right – angle α from +121° to +180°. If it is impossible to isolate the dominant tooth of the complex

QRS in limb leads, so-called. ecphyvase QRS complex, the position of the EOS should be considered uncertain.

The position of the EOS can be determined by several methods.

Graphic (planimetric) method. It is required to first calculate on the electrocardiogram the algebraic sum of the teeth of the ventricular complex (Q + R + S) in standard leads I and III (most often in I and III).

To do this, measure in millimeters the size of each wave of one ventricular QRS complex, taking into account that the Q and S waves have a minus sign, and the R wave has a plus sign. If any wave on the electrocardiogram is missing, then its value is equal to zero

(0). The positive or negative value of the algebraic sum of the QRS waves on an arbitrarily selected scale is plotted on the positive or negative arm of the axis of the corresponding lead of the six-axis Bailey coordinate system. From the ends of these projections, perpendiculars to the axes of the leads are restored, the intersection point of which is connected to the center of the system. This line will be the exact position of the EOS.

Drawing. An example of a graphical method for determining EOS

Table method. Special tables are used by R.Ya. Written, diagrams according to Diede et al., using the principle of algebraic addition of the amplitudes of the teeth, stated above.

Visual (algorithmic) method. Less accurate, but easiest to use practical application. It is based on the principle that the maximum positive or negative value of the algebraic sum of the QRS complex waves is observed in the lead that approximately coincides with the position of the electrical axis of the heart.

Thus, in the normal position of the EOS R II ≥R I ≥R III, in leads III and aVL approximately R=S.

With a deviation to the left - R I >R II >R III, S III >R III (With a moderate deviation, as a rule, RII ≤SII, with a pronounced deviation to the left -

The greatest electrical activity of the ventricular myocardium is detected during the period of their excitation. In this case, the resultant of the resulting electrical forces (vector) occupies a certain position in the frontal plane of the body, forming an angle  (it is expressed in degrees) relative to the horizontal zero line (I standard lead). The position of this so-called electrical axis of the heart (EOS) is assessed by the size of the QRS complex waves in standard leads, which makes it possible to determine the angles and, accordingly, the position of the electrical axis of the heart. Angle is considered positive if it is located below the horizontal line, and negative if it is located above. This angle can be determined by geometric construction in Einthoven’s triangle, knowing the size of the QRS complex teeth in two standard leads. In practice, special tables are used to determine the angle  (they determine the algebraic sum of the teeth of the QRS complex in standard leads I and II, and then find the angle  using the table). There are five options for the location of the heart axis: normal, vertical position (intermediate between the normal position and the levogram), deviation to the right (pravogram), horizontal (intermediate between the normal position and the levogram), deviation to the left (levogram).

All five options are schematically presented in Fig. 23–9.

Rice.23–9 .Optionsdeviationselectricalaxeshearts. They are assessed by the size of the main (maximum amplitude) waves of the QRS complex in leads I and III. PR - right hand, LR - left hand, LN - left leg.

 Normogram(normal position of the EOS) is characterized by an anglefrom +30° to +70°. ECG signs:

 the R wave prevails over the S wave in all standard leads;

 maximum R wave in standard lead II;

 in aVL and aVF R waves also predominate, and in aVF it is usually higher than in aVL.

Normogram formula: R II >R I >R III.

 Verticalposition characterized by an angle from +70° to +90°. ECG signs:

 equal amplitude of the R waves in standard leads II and III (or in lead III slightly lower than in lead II);

 the R wave in standard lead I is small, but its amplitude exceeds the amplitude of the S wave;

 The QRS complex in aVF is positive (high R wave predominates), and in aVL it is negative (deep S wave predominates).

Formula: R II R III >R I, R I >S I.

 Pravogram. Deviation of the EOS to the right (pravogram) - anglemore than +90°. ECG signs:

 the R wave is maximum in standard lead III, in leads II and I it progressively decreases;

 the QRS complex in lead I is negative (the S wave predominates);

 in aVF a high R wave is characteristic, in aVL - a deep S wave with a small R wave;

Formula: R III >R II >R I, S I >R I.

 Horizontalposition characterized by an anglefrom +30° to 0°. ECG signs:

 the R waves in leads I and II are almost the same, or the R wave in lead I is slightly higher;

 in standard lead III, the R wave has a small amplitude, the S wave exceeds it (on inspiration, the r wave increases);

 in aVL the R wave is high, but slightly smaller than the S wave;

 in aVF the R wave is not high, but exceeds the S wave.

Formula: R I R II >R III, S III >R III, R aVF >S aVF.

 Levogram. Deviation of the EOS to the left (levogram) - angle less than 0° (up to –90°). ECG signs:

 the R wave in lead I exceeds the R waves in standard leads II and III;

 the QRS complex in lead III is negative (the S wave predominates; sometimes the r wave is completely absent);

 in aVL the R wave is high, almost equal to or greater than the R wave in standard lead I;

 in aVF, the QRS complex resembles that in standard lead III.

Formula: R I >R II >R III, S III >R III, R aVF

Papproximate grade provisions electrical axes hearts. To remember the differences between the right-hand and left-hand grammars, students use a witty schoolboy technique, which consists of the following. When examining your palms, bend the thumb and index fingers, and the remaining middle, ring and little fingers are identified with the height of the R wave. “Read” from left to right, like an ordinary line. Left hand - levogram: the R wave is maximum in standard lead I (the first highest finger is the middle finger), in lead II it decreases (ring finger), and in lead III it is minimal (little finger). The right hand is a right hand, where the situation is reverse: the R wave increases from lead I to lead III (as does the height of the fingers: little finger, ring finger, middle finger).

Causes of deviation of the electrical axis of the heart. The position of the electrical axis of the heart depends on both cardiac and extracardiac factors.

 In people with a high diaphragm and/or a hypersthenic constitution, the EOS takes on a horizontal position or even a levogram appears.

 In tall, thin people with low standing, the diaphragm of the EOS is normally located more vertically, sometimes up to the right angle.

Deviation of EOS is most often associated with pathological processes. As a result of the predominance of myocardial mass, i.e. ventricular hypertrophy, the EOS deviates towards the hypertrophied ventricle. However, if during left ventricular hypertrophy the deviation of the EOS to the left almost always occurs, then for its deviation to the right the right ventricle must be significantly hypertrophied, since its mass in a healthy person is 6 times less than the mass of the left ventricle. Nevertheless, it must immediately be pointed out that, despite the classical ideas, at present, EOS deviation is not considered a reliable sign of ventricular hypertrophy.

Introduction

In this issue I will briefly touch on these issues. From the next issues we will begin to study pathology.

Also, previous issues and materials for a more in-depth study of ECG can be found in the "" section.

1. What is the resulting vector?

Inextricably linked with the concept of the resulting vector of ventricular excitation in the frontal plane.

The resulting vector of ventricular excitation is the sum of three moment vectors of excitation: the interventricular septum, the apex and base of the heart.
This vector has a certain orientation in space, which we interpret in three planes: frontal, horizontal and sagittal. In each of them, the resulting vector has its own projection.

2. What is the electrical axis of the heart?

Electric axis hearts called the projection of the resulting vector of ventricular excitation in the frontal plane.

The electrical axis of the heart may deviate from its normal position either to the left or to the right. The exact deviation of the electrical axis of the heart is determined by the alpha (a) angle.

3. What is the alpha angle?

Let us mentally place the resulting vector of ventricular excitation inside Einthoven’s triangle. Corner, formed by the direction of the resulting vector and the I axis of the standard lead, and is required angle alpha.

The value of the alpha angle are found using special tables or diagrams, having previously determined on the electrocardiogram the algebraic sum of the teeth of the ventricular complex (Q + R + S) in standard leads I and III.

Find the algebraic sum of the teeth ventricular complex is quite simple: measure in millimeters the size of each wave of one ventricular QRS complex, taking into account that the Q and S waves have a minus sign (-), since they are below the isoelectric line, and the R wave has a plus sign (+). If any wave on the electrocardiogram is missing, then its value is equal to zero (0).

If the alpha angle is within 50-70°, talk about the normal position of the electrical axis of the heart (the electrical axis of the heart is not deviated), or a normogram. When the electrical axis of the heart deviates right angle alpha will be determined in within 70-90°. In everyday life, this position of the electrical axis of the heart is called a legal grammar.

If the alpha angle is greater than 90° (for example, 97°), it is considered that this ECG has block of the posterior branch of the left bundle branch.
By defining the alpha angle within 50-0° we speak of deviation of the electrical axis of the heart to the left, or levogram.
A change in the alpha angle within 0 - minus 30° indicates a sharp deviation of the electrical axis of the heart to the left or, in other words, about the sharp leftogram.
And finally, if the value of the alpha angle is less than minus 30° (for example, minus 45°), they speak of anterior branch blockade left bundle branch.

Determination of the deviation of the electrical axis of the heart by the alpha angle using tables and diagrams is carried out mainly by doctors in functional diagnostics offices, where the corresponding tables and diagrams are always at hand.
However, it is possible to determine the deviation of the electrical axis of the heart without the necessary tables.

In this case, the deviation of the electrical axis is determined by analyzing the R and S waves in standard leads I and III. In this case, the concept of the algebraic sum of the teeth of the ventricular complex is replaced by the concept "defining tooth" QRS complex, visually comparing the R and S waves in absolute value. They speak of an “R-type ventricular complex,” meaning that in this ventricular complex the R wave is higher. On the contrary, in "S-type ventricular complex" The defining wave of the QRS complex is the S wave.

If on the electrocardiogram in the first standard lead the ventricular complex is represented by the R-type, and the QRS complex in the third standard lead has an S-type shape, then in this case the electrical the axis of the heart is deviated to the left (levogram). Schematically, this condition is written as RI-SIII.

On the contrary, if in standard lead I we have the S-type of the ventricular complex, and in lead III the R-type of the QRS complex, then the electrical axis of the heart deviated to the right (pravogram).
Simplified, this condition is written as SI-RIII.

The resulting vector of ventricular excitation is normally located in frontal plane like this that its direction coincides with the direction of axis II of the standard lead.

The figure shows that the amplitude of the R wave in standard lead II is greatest. In turn, the R wave in standard lead I exceeds the RIII wave. Under this condition of the ratio of R waves in various standard leads, we have normal position of the electrical axis of the heart(the electrical axis of the heart is not deviated). A short notation for this condition is RII>RI>RIII.

4. What is the electrical position of the heart?

Close in meaning to the electrical axis of the heart is the concept electrical position of the heart. Under the electrical position of the heart imply the direction of the resulting vector of ventricular excitation relative to axis I of the standard lead, taking it as if it were the horizon line.

Distinguish vertical position of the result vector relative to axis I of the standard lead, calling it the vertical electrical position of the heart, and the horizontal position of the vector is the horizontal electrical position of the heart.

There is also a basic (intermediate) electrical position of the heart, semi-horizontal and semi-vertical. The figure shows all the positions of the resulting vector and the corresponding electrical positions of the heart.

For these purposes, the ratio of the amplitude of the K waves of the ventricular complex in the unipolar leads aVL and aVF is analyzed, keeping in mind the features of the graphic display of the resulting vector with the recording electrode (Fig. 18-21).

Conclusions from this issue of the newsletter “Learning ECG step by step - it’s easy!”:

1. The electrical axis of the heart is the projection of the resulting vector in the frontal plane.

2. The electrical axis of the heart is capable of deviating from its normal position either to the right or to the left.

3. The deviation of the electrical axis of the heart can be determined by measuring the alpha angle.

A small reminder:

4. The deviation of the electrical axis of the heart can be determined visually.
RI-SШ levogram
RII > RI > RIII normogram
SI-RIII spelling

5. The electrical position of the heart is the position of the resulting vector of excitation of the ventricles in relation to axis I of the standard lead.

6. On the ECG, the electrical position of the heart is determined by the amplitude of the R wave, comparing it in leads aVL and aVF.

7. The following electrical positions of the heart are distinguished:

Conclusion.

You can find everything you need to study deciphering an ECG and determining the electrical axis of the heart in the section of the site: " ". The section contains both clear articles and video tutorials.
If there are problems with understanding or deciphering, we are waiting for questions on the forum for free consultations with a doctor -.

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Additional Information:

1. The concept of “inclination of the electrical axis of the heart”

In some cases, when visually determining the position of the electrical axis of the heart, a situation is observed when the axis deviates from its normal position to the left, but clear signs of a leftogram are not detected on the ECG. The electrical axis is, as it were, in a borderline position between the normogram and the levogram. In these cases, they talk about a tendency to levogramma. In a similar situation, deviations of the axis to the right indicate a tendency towards a right-hand grammar.

2. The concept of “uncertain electrical position of the heart”

In some cases, it is not possible to find on the electrocardiogram the conditions described for determining the electrical position of the heart. In this case, they speak of an uncertain position of the heart.

Many researchers believe that practical significance the electrical position of the heart is small. It is usually used for more accurate topical diagnostics pathological process occurring in the myocardium, and to determine hypertrophy of the right or left ventricle.

Training video for determining the EOS (electrical axis of the heart) using an ECG

The heart, like any human organ, is controlled by packets of impulses coming from the brain through the nervous system. It is obvious that any violation of the control system leads to serious consequences for the body.

The electrical axis of the heart (EOS) is the total vector of all impulses observed in the conduction system of this organ during one contraction cycle. Most often it coincides with the anatomical axis.

The norm for the electrical axis is the position in which the vector is located diagonally, that is, directed down and to the left. However, in some cases this parameter may deviate from the norm. Based on the position of the axis, a cardiologist can learn a lot about the work of the heart muscle and possible problems.

Depending on a person’s physique, there are three main values ​​of this indicator, each of which is considered normal under certain conditions.

• In most patients with a normal build, the angle between the horizontal coordinate and the vector of electrodynamic activity ranges from 30° to 70°.
• For asthenics and thin people normal value the angle reaches 90°.
• In short, dense people, on the contrary, the angle of inclination is smaller - from 0° to 30°.

Thus, the position of the EOS is influenced by the constitution of the body, and for each patient the norm for this indicator is relatively individual.

The possible position of the EOS is shown in this photo:

Reasons for changes

In itself, deviation of the vector of electrical activity of the heart muscle is not a diagnosis, but may indicate, among other things, serious disorders. Its position is influenced by many parameters:

• organ anatomy leading to hypertrophy or;
• malfunctions in the conductive system of the organ, in particular, which is responsible for conducting nerve impulses to the ventricles;
• cardiomyopathies due to various causes;
• chronic heart failure;
• persistent hypertension for a long time;
• Chronic respiratory diseases, such as obstructive pulmonary disease or bronchial asthma, can lead to deviation of the electrical axis to the right.

In addition to the above reasons, temporary deviations in EOS can cause phenomena not directly related to the heart: pregnancy, ascites (fluid accumulation in the abdominal cavity), intra-abdominal tumors.

How to determine on an electrocardiogram

The EOS angle is considered one of the main parameters that is studied at. For a cardiologist, this parameter is an important diagnostic indicator, the abnormal value of which clearly signals various disorders and pathologies.

By studying the patient's ECG, the diagnostician can determine the position of the EOS by examining QRS complex waves, which show the work of the ventricles on the graph.

An increased amplitude of the R wave in the I or III chest leads of the graph indicates that the electrical axis of the heart is deviated to the left or right, respectively.

In the normal position of the EOS, the greatest amplitude of the R wave will be observed in the II chest lead.

Diagnosis and additional procedures

As mentioned earlier, deviation of the EOS to the right on the ECG is not considered a pathology in itself, but serves as a diagnostic sign of disorders of its functioning. In the vast majority of cases this symptom indicates that the right ventricle and/or right atrium abnormally enlarged, and finding out the causes of such hypertrophy allows you to make a correct diagnosis.

For more accurate diagnosis The following procedures may apply:

• ultrasound examination is a method with the highest information content showing changes in the anatomy of an organ;
• Chest x-ray may reveal myocardial hypertrophy;
• used if, in addition to EOS deviation, there are also rhythm disturbances;
• ECG under stress helps in detecting myocardial ischemia;
• Coronary angiography (CAG) diagnoses lesions of the coronary arteries, which can also lead to EOS tilt.

What diseases are caused

A pronounced deviation of the electrical axis to the right can signal the following diseases or pathologies:

• Cardiac ischemia. , characterized by blockage of the coronary arteries that supply blood to the heart muscle. When uncontrolled, it leads to myocardial infarction.
• Congenital or acquired. This is the name given to the narrowing of this large vessel, which prevents the normal flow of blood from the right ventricle. Leads to increased systolic blood pressure and, as a consequence, to myocardial hypertrophy.
• Atrial fibrillation. Messy electrical activity atria, which ultimately can cause a cerebral stroke.
• Chronic cor pulmonale . Occurs when there is a malfunction of the lungs or pathologies of the chest, which lead to the inability of the left ventricle to function fully. Under such conditions, the load on the right ventricle increases significantly, which leads to its hypertrophy.
• Defect interatrial septum . is expressed in the presence of holes in the septum between the atria, through which blood can be discharged from the left side to the right. As a result, heart failure and pulmonary hypertension develop.
• Mitral valve stenosis- between the left atrium and the left ventricle, which leads to difficulty in diastolic blood flow. Refers to acquired defects.
• Thromboembolism pulmonary artery . Caused by blood clots, which, after occurring in large vessels, move through the circulatory system and.
• Primary pulmonary hypertension - blood in the pulmonary artery, which is caused by various reasons.

In addition to the above, a tilt of the EOS to the right may be a consequence of poisoning with tricyclic antidepressants. The somatotropic effect of such drugs is achieved by the influence of the substances they contain on the conductive system of the heart, and thus they can harm it.

What to do

If the electrocardiogram showed a tilt of the electrical axis of the heart to the right, it should be without delay, carry out a more extensive diagnostic examination at the doctor's. Depending on the problem identified during a more in-depth diagnosis, the doctor will prescribe appropriate treatment.

The heart is one of the most important parts human body, and therefore his condition should be the subject increased attention. Unfortunately, they often remember about it only when it starts to hurt.

To prevent such situations, you need to adhere to at least general recommendations for the prevention of heart problems: eat right, don’t neglect in a healthy way life, and be examined by a cardiologist at least once a year.

If in the results of the electrocardiogram there is a record of a deviation of the electrical axis of the heart, a more in-depth diagnosis should be immediately carried out to determine the causes of this phenomenon.