Normal cardiac axis. EOS is deviated to the left: what does it mean, causes and treatment
What exactly does the ECG machine record?
The electrocardiograph records total electrical activity hearts, or more precisely, the difference in electrical potential (voltage) between 2 points.
Where in the heart a potential difference arises? It's simple. At rest, myocardial cells are charged negatively from the inside and positively charged from the outside, while a straight line (= isoline) is recorded on the ECG tape. When an electrical impulse (excitation) arises and propagates in the conduction system of the heart, cell membranes move from a resting state to an excited state, changing polarity to the opposite (the process is called depolarization). In this case, the membrane becomes positive from the inside, and negative from the outside due to the opening of a number of ion channels and the mutual movement of K + and Na + ions (potassium and sodium) from and into the cell. After depolarization, after a certain time, the cells enter a resting state, restoring their original polarity (minus on the inside, plus on the outside), this process is called repolarization.
The electrical impulse sequentially spreads throughout the parts of the heart, causing depolarization of myocardial cells. During depolarization, part of the cell becomes positively charged from the inside, and part - negatively. Arises potential difference. When the entire cell is depolarized or repolarized, there is no potential difference. Stages depolarization corresponds to contraction cells (myocardium), and stages repolarization - relaxation. The ECG records the total potential difference from all myocardial cells, or, as it is called, electromotive force of the heart(EMF of the heart). EMF of the heart is a tricky but important thing, so let’s return to it a little lower.
Schematic location of the cardiac EMF vector(in the center)
at one point in time.
ECG leads
As stated above, the electrocardiograph records voltage (electrical potential difference) between 2 points, that is, in some lead. In other words, the ECG device records on paper (screen) the magnitude of the projection of the electromotive force of the heart (cardiac emf) onto any lead.
A standard ECG is recorded in 12 leads:
- 3 standard(I, II, III),
- 3 reinforced from the limbs (aVR, aVL, aVF),
- and 6 infant(V1, V2, V3, V4, V5, V6).
1) Standard leads(suggested by Einthoven in 1913).
I - between the left hand and the right hand,
II - between the left leg and right arm,
III - between the left leg and left arm.
simplest(single-channel, i.e. recording no more than 1 lead at any time) cardiograph has 5 electrodes: red(applied to the right hand), yellow (left hand), green (left leg), black(right leg) and pectoral (suction cup). If you start with right hand and move in a circle, we can say that it turned out to be a traffic light. The black electrode denotes “ground” and is needed only for safety purposes for grounding, so that a person does not get an electric shock in the event of a possible breakdown of the electrocardiograph.
Multichannel portable electrocardiograph.
All electrodes and suction cups differ in color and location.
2) Reinforced limb leads(proposed by Goldberger in 1942).
The same electrodes are used as for recording standard leads, but each of the electrodes in turn connects 2 limbs at once, and a combined Goldberger electrode is obtained. In practice, recording of these leads is done by simply switching the handle on a single-channel cardiograph (i.e., there is no need to rearrange the electrodes).
aVR- enhanced abduction from the right hand (short for augmented voltage right - enhanced potential on the right).
aVL- increased abduction from the left hand (left - left)
aVF- increased abduction from the left leg (foot - leg)
3) Chest leads(proposed by Wilson in 1934) are recorded between the chest electrode and the combined electrode from all 3 limbs.
The locations of the chest electrode are located sequentially along the anterolateral surface chest from midline body to the left hand.
I don’t indicate too much detail, because it is not necessary for non-specialists. The principle itself is important (see figure).
V1 - in the IV intercostal space along the right edge of the sternum.
V2
V3
V4 - at the level of the apex of the heart.
V5
V6 - along the left mid-axillary line at the level of the apex of the heart.
Location of 6 chest electrodes when recording an ECG.
The 12 leads indicated are standard. If necessary, “write” and additional leads:
- according to Neb(between points on the surface of the chest),
- V7 - V9(continuation of chest leads to left half backs),
- V3R - V6R(mirror reflection of chest leads V3 - V6 on the right half of the chest).
Lead meaning
For reference: quantities can be scalar and vector. Scalar quantities haveonly the size (numerical value), for example: mass, temperature, volume. Vector quantities, or vectors, haveboth magnitude and direction ; for example: speed, force, electric field strength, etc. Vectors are indicated by an arrow above the Latin letter.
Why was it invented? so many leads? EMF of the heart is vector EMF of the heart in a 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. First 6 leads(3 standard and 3 reinforced from the limbs) reflect the EMF of the heart in the so-called frontal plane(see figure) 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.
The relative position of standard and enhanced leads in the frontal plane.
But there is an error in the picture:
aVL and lead III are NOT on the same line.
Below are the correct drawings.
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.
When analyzing an ECG, projections of the EMF vector of the heart are used, so this ECG analysis is called vector.
Note. The material below may seem very complex. This is fine. When you study the second part of the series, you will return to it, and it will become much clearer.
Electrical axis of the heart (EOS)
If you draw circle and through its center draw lines corresponding to the directions of three standard and three reinforced limb leads, then we get 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.
Formation of a 6-axis coordinate system.
Missing leads are replaced by a continuation of existing ones.
Electrical axis of the heart- this is a 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. The electrical axis of the heart is expressed quantitatively angle α between the axis itself and the positive (right) half of the axis of standard lead I, located horizontally.
It is clearly seen that the same EMF of the heart in projections
gives to different leads various shapes curves.
Determination rules the positions of the EOS in the frontal plane are as follows: electrical axis of the heart matches with that of the first 6 leads in which the highest positive teeth, And perpendicular the lead in which the size of the positive teeth equal to size negative teeth. Two definition examples electrical axis hearts 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°.
Options for the location of the electrical axis of the heart
in the frontal plane.
Fine electrical axis of the heart roughly matches his anatomical axis(y skinny people is directed more vertically from the average values, and in obese people - more horizontally). For example, when hypertrophy(proliferation) of the right ventricle, the axis of the heart deviates to the right. At conduction disorders the electrical axis of the heart can 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.
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.
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.
The electrocardiogram reflects electrical processes only in the myocardium: depolarization (excitation) and repolarization (restoration) of myocardial cells.
Ratio ECG intervals With phases cardiac cycle (ventricular systole and diastole).
Normally, depolarization leads to contraction of the muscle cell, and repolarization leads to relaxation. To simplify further, instead of “depolarization-repolarization” I will sometimes use “contraction-relaxation”, although this is not entirely accurate: there is a concept “ electromechanical dissociation“, in which depolarization and repolarization of the myocardium do not lead to its visible contraction and relaxation. I wrote a little more about this phenomenon earlier.
Elements of a normal ECG
Before moving on to deciphering the ECG, you need to understand what elements it consists of.
Waves and intervals on the ECG.
It's interesting that abroad P-Q interval usually called P-R.
Any ECG consists of teeth, segments And intervals.
TEETH- these are convexities and concavities on the electrocardiogram.
The following waves are distinguished on the ECG:
- P(atrial contraction)
- Q, R, S(all 3 teeth characterize contraction of the ventricles),
- T(ventricle relaxation)
- U(non-permanent tooth, rarely recorded).
SEGMENTS
A segment on an ECG is called straight line segment(isolines) between two adjacent teeth. The most important segments are 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.
INTERVALS
The interval consists of tooth (complex of teeth) and segment. Thus, interval = tooth + segment. The most important are the P-Q and Q-T intervals.
Waves, segments and intervals on the ECG.
Pay attention to large and small cells (more about them below).
QRS complex waves
Since the ventricular myocardium is more massive than the atrial myocardium and has not only walls, but also a massive interventricular septum, the spread of excitation in it is characterized by the appearance of a complex complex QRS on the ECG. How to do it right highlight the teeth in it?
First of all they evaluate amplitude (sizes) of individual teeth QRS complex. If the amplitude exceeds 5 mm, the tooth indicates capital letter Q, R or S; if the amplitude is less than 5 mm, then lowercase (small): q, r or s.
The R wave (r) is called any positive(upward) wave that is part of the QRS complex. If there are several teeth, subsequent teeth indicate strokes: R, R’, R”, etc. Negative (downward) wave of the QRS complex, located before the R wave, is denoted as Q(q), and after - like S(s). If there are no positive waves at all in the QRS complex, then the ventricular complex is designated as QS.
Variants of the QRS complex.
Normal tooth Q reflects depolarization of the interventricular septum, tooth R- the bulk of the ventricular myocardium, tooth S- basal (i.e. near the atria) sections of the interventricular septum. The R V1, V2 wave reflects the excitation of the interventricular septum, and R V4, V5, V6 - the excitation of the muscles of the left and right ventricles. Necrosis of areas of the myocardium (for example, with myocardial infarction) causes the Q wave to widen and deepen, so close attention is always paid to this wave.
ECG analysis
General scheme ECG interpretation
- Checking the correctness of ECG registration.
- Analysis heart rate and conductivity:
- assessment of heart rate regularity,
- heart rate (HR) counting,
- determination of the source of excitation,
- conductivity assessment.
- QRS complex analysis,
- analysis of the RS - T segment,
- T wave analysis,
- Q-T interval analysis.
Normal electrocardiogram.
1) Checking the correct ECG registration
At the beginning of each ECG tape there must be calibration signal- 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. Without a calibration signal, the ECG recording is considered incorrect. Normally, in at least one of the standard or enhanced limb leads, the amplitude should exceed 5 mm, and in the chest leads - 8 mm. If the amplitude is lower, it is called reduced ECG voltage, which occurs in some pathological conditions.
Reference millivolt on the ECG (at the beginning of the recording).
2) 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 variation in the duration of individual R-R intervals is allowed no more than ± 10% from their average duration. If the rhythm is sinus, it is usually regular.
- heart rate counting(heart rate)
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 teeth R - R.
At belt speed 50 mm/s: HR = 600 /
(number of large squares).
At belt speed 25 mm/s: HR = 300 /
(number of large squares).
On the overlying ECG interval R-R is equal approximately 4.8 large cells, which at a speed of 25 mm/s gives300 / 4.8 = 62.5 beats/min.
At a speed of 25 mm/s each small cell 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, it is usually considered maximum and minimum heart rate 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 pacemaker, 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 confusingly combined, which can lead to incorrect diagnosis and improper treatment. To correctly determine the source of excitation on an ECG, you need to know well conduction system of the heart.
Sinus rhythm(this is a normal rhythm, and all other rhythms are pathological).
The source of excitation is in sinoatrial node. Signs on the ECG:
- in standard lead II, the P waves are always positive and are located before each QRS complex,
- P waves in the same lead have the same shape at all times.
P wave in sinus rhythm.
ATRIAL rhythm. If the excitation source is in lower sections atria, then the excitation wave propagates to the atria from bottom to top (retrograde), therefore:
- in leads II and III the P waves are negative,
- There are P waves before each QRS complex.
P wave during atrial rhythm.
Rhythms from the AV connection. If the pacemaker is in the atrioventricular ( atrioventricular node) node, then the ventricles are excited as usual (from top to bottom), and the atria - retrograde (i.e. from bottom to top). At the same time, on the ECG:
- P waves may be absent because they are superimposed on normal QRS complexes,
- P waves can be negative, located after the QRS complex.
Rhythm from the AV junction, superimposition of the P wave on the QRS complex.
Rhythm from the AV junction, the P wave is located after the QRS complex.
Heart rate with a rhythm from the AV junction is less than sinus rhythm and is approximately 40-60 beats per minute.
Ventricular, or IDIOVENTRICULAR, rhythm(from Latin ventriculus [ventrikulyus] - ventricle). In this case, the source of rhythm is the ventricular conduction system. Excitation spreads through the ventricles in the wrong way and is therefore slower. Features of idioventricular rhythm:
- QRS complexes are widened and deformed (they look “scary”). Normally, the duration of the QRS complex is 0.06-0.10 s, therefore, with this rhythm, the QRS exceeds 0.12 s.
- there is no pattern between QRS complexes and P waves because the AV junction does not release impulses from the ventricles, and the atria can be excited from sinus node, as normal.
- Heart rate less than 40 beats per minute.
Idioventricular rhythm. The P wave is not associated with the QRS complex.
- conductivity assessment.
To properly account for conductivity, the recording speed is taken into account.
To assess conductivity, measure:
- duration P wave(reflects the speed of impulse transmission through the atria), normally up to 0.1 s.
- duration interval P - Q(reflects the speed of impulse conduction from the atria to the ventricular myocardium); interval P - Q = (wave P) + (segment P - Q). Fine 0.12-0.2 s.
- duration QRS complex(reflects the spread of excitation through the ventricles). Fine 0.06-0.1 s.
- internal deviation interval in leads V1 and V6. This is the time between the beginning of the QRS complex and the R wave. Normal in V1 up to 0.03 s and in V6 up to 0.05 s. Used mainly to recognize bundle branch blocks and to determine the source of excitation in the ventricles in the case of ventricular extrasystole (extraordinary contraction of the heart).
Measuring the internal deviation interval.
3) Determination of the electrical axis of the heart.
In the first part of the series about ECG it was explained what it is electrical axis of the heart and how it is determined in the frontal plane.
4) Atrial P wave analysis.
Normally, in leads I, II, aVF, V2 - V6, the P wave 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 high P waves of normal duration in leads II, III, aVF are characteristic of right atrial hypertrophy, for example, when “ pulmonary heart”.
- Split with 2 apexes, widened P wave in leads I, aVL, V5, V6 is characteristic of left atrial hypertrophy, for example, with mitral valve defects.
Formation of the P wave (P-pulmonale) with hypertrophy of the right atrium.
Formation of the P wave (P-mitrale) with hypertrophy of the left atrium.
P-Q interval: fine 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).
AV block There are 3 degrees:
- I degree - the P-Q interval is increased, but each P wave has its own QRS complex ( 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 carrying out in the AV node. The atria and ventricles contract at their own rhythm, independently of each other. Those. idioventricular rhythm occurs.
5) Ventricular QRST analysis:
- QRS complex analysis.
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 R wave height, 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 (in this case, the r wave of V1 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) “ transition zone” (equality of 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 point at which the QRS complex transitions to the S-T segment is called the 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 T I > T III, and T V6 > T V1. 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 there is a small U wave, which is formed due to short-term increased excitability of the ventricular myocardium after their repolarization.
6) Electrocardiographic report.
Should include:
- Source of rhythm (sinus or not).
- Regularity of rhythm (correct or not). Usually sinus rhythm is normal, 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)
Examples of conclusions(not quite complete, but real):
Sinus rhythm with heart rate 65. Normal position of the electrical axis of the heart. No pathology was identified.
Sinus tachycardia with heart rate 100. Single supraventricular extrasystole.
Sinus rhythm with heart rate 70 beats/min. Incomplete blockade right leg His bundle. Moderate metabolic changes in the myocardium.
Examples of ECG with specific diseases of cardio-vascular system- next time.
ECG interference
Due to frequently asked questions in the comments about the type of ECG I will tell you about interference which may appear on the electrocardiogram:
Three types of ECG interference(explained below).
Interference on an ECG in the lexicon of health workers is called tip-off:
a) inrush currents: network pickup in the form of regular oscillations with a frequency of 50 Hz, corresponding to the frequency of alternating electric current in the socket.
b) " swimming"(drift) of the isoline due to poor contact of the electrode with the skin;
c) interference caused by muscle tremors
(irregular frequent vibrations are visible).
In cardiological practice, there is a special term that reflects cardiac electrical processes. It is called the electrical axis of the heart (EOS). Its direction characterizes the bioelectric changes occurring inside the heart during its contraction, or rather their total value.
Atypical muscles make up the conduction system. They ensure the synchronization of heartbeats. An electrical impulse is generated in the sinus node. This gives rise to myocardial contraction. It is for this reason that the normal rhythm of the human heart is called sinus.
As already stated, various diseases have different effects on the angle of inclination of the EO.
What does it mean if the electrical axis of the heart is deviated to the left? This may be a symptom of left ventricular hypertrophy. That is, it increases and its overload occurs. This can occur with prolonged high blood pressure. Vessels have great resistance to blood flow. Therefore, the left ventricle exerts great effort. It grows, which means it develops. This is precisely the main reason for moving the axis to the left.
Hypertrophy can develop when the valvular section of the left ventricle is damaged. This is caused by ostial aortic stenosis. In this condition, there are great difficulties in sending blood out of the left ventricle, or it becomes overloaded with returning blood. Such disorders may be acquired or may be congenital. In most cases, the ventricle enlarges after attacks of rheumatism. The disease also occurs in athletes. In the latter case, a sports career may end suddenly.
If the electrical axis of the heart is shifted to the left, this may indicate all sorts of heart blockades and conduction disturbances inside the ventricle.
The electrical axis of the heart is shifted to the right with enlargement of the right ventricle. Coming out of it, the blood is transported to the lungs for oxygen enrichment. Hypertrophy can be provoked various diseases pulmonary system, such as asthma, increased pulmonary pressure or obstructing. Hypertrophy also occurs with pulmonary stenosis or incorrect functioning of the tricuspid valve. In addition, the disease can be a consequence of ischemia, cardiomyopathy, etc.
These diagnoses cannot be made only by the location of the EOS. This is only an additional indicator determined when identifying various kinds ailments. If the electrical axis of the heart is deviated beyond the range of zero to plus ninety degrees, you need to consult a doctor and conduct some research.
As is known, the main factor regulating axis displacement is hypertrophy. This disease can be determined through ultrasound examination. In general, all diseases that cause a displacement of the electrical axis of the heart are characterized by a variety of clinical manifestations and several additional studies need to be conducted to identify them. A sudden change in the position of the axis, detected for the first time on an electrocardiogram, can be provoked by some kind of cardiac blockade.
Treatment for displacement of the electrical axis of the heart is not required. This parameter is one of the electrocardiological signs, based on which it is necessary to find out the reasons for its manifestation. And this will only be done by an experienced cardiologist based on the results of the prescribed examination.
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 office doctors functional diagnostics, where the relevant 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 -.
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 diagnosis 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
Website - medical portal online consultations with pediatric and adult doctors of all specialties. You can ask a question on the topic "ecg horizontal position eos" and get it for free online consultation doctor
Ask your questionQuestions and answers on: ECG horizontal position EOS
2015-08-28 09:09:20
Marina asks:
Hello! I am 24 years old and have been involved in active sports before. The ECG results alarmed me, according to the ECG: 81 beats per minute; Horizontal position EOS: 5 degrees; Changes in the myocardium in the anteroseptal region of the left ventricle (to differentiate metabolic disorders from coronary circulation disorders).
Answers Bugaev Mikhail Valentinovich:
Hello. I don’t think that at the age of 24 you can have coronary circulatory disorders, unless congenital anomaly heart vessels. I don’t see anything wrong with the results described.
2015-04-15 10:07:16
Alexandra asks:
Good afternoon I'm pregnant, 33 weeks. I did an ECG. Here is the result.
The rhythm is ectopic lower atrial, regular, heart rate 78. Horizontal position of the EOS. AV block 1st degree. Signs of left ventricular hypertrophy. Slightly pronounced changes in the myocardium in the anteroseptal region, upper and lower walls of the left ventricle.
This is serious? Can I give birth myself and in a regular maternity hospital? Thank you for your reply.
Answers Bugaev Mikhail Valentinovich:
Hello. So far I don’t see anything that requires intervention. But I would also do an ultrasound of the heart and daily ECG monitoring according to Holter. Do you have any complaints? Are there any loss of consciousness or fainting states? What PQ interval did you intend?
2014-06-08 13:08:00
Asks Zharikova Victoria:
The patient is 51 years old, has type 2 diabetes for 14 years, moderate severity in the stage of decompensation. He stated that he had experienced deep emotional stress and provided an ECG cardiogram: sinus rhythm, heart rate 69 per minute, horizontal position of the EOS. Do you have heart problems - warning signs of a heart attack or stroke? Did emotional experience have an impact?
Answers Bugaev Mikhail Valentinovich:
Hello. From this “description” of the ECG it is impossible to say anything about possible problems with the heart, everything described is normal. But that doesn't mean anything. The very fact of having diabetes is a risk factor for coronary heart disease and other vascular problems. You need to see a competent doctor.
2013-12-15 17:29:02
Aizhan asks:
Hello! On the ECG I was diagnosed with the following: sinus rhythm, GSS - 7561, horizontal position of the EOS. PQ 0.14 QRS 0.08 Q-T 0.34 R-R 0.80 Heart rate 7561 per 1 min. R>R>R
I II III
Transition zone V 3 Voltage is normal. What does this mean? What does this mean? I am 40 years old. Weight 52 kg. There are no thyroid diseases, sugar is normal, chronic pyelonephritis since 1999. Thanks in advance.
2013-11-02 08:46:56
Natalya asks:
Good afternoon, I am 37 years old and have frequent pain in my heart. I did an ECG. Sinus tachycardia with a heart rate of 92 beats per minute. Horizontal position of the EOS. Insufficient growth of the R wave in V1-V4. There is no evidence of acute focal pathology.
2012-10-12 10:50:25
Oksana asks:
Hello, I did it for my husband ECG of the heart and this is the conclusion: sinus rhythm with heart rate 86/min, horizontal position of the EOS, focal changes in back wall left ventricle! what does this mean, and can it affect its work? works as a firefighter!!! Thanks for the answer
2011-07-17 00:03:44
Faith asks:
Good day! Our close male relative, 45 years old, recently had an ECG,
How can I determine if there is hyperkalemia using an ECG? Please determine whether it is or not,
Here is the result of the ECG
HERE is the result of the ECG,
Rhythm: sinus, regular;
HR-66;
EOS position: 11 horizontal (N+0-29 degrees)
PQ Duration: 154
QRS: 92
QT/QT corr: 448
T waves: + in 1.2,AVF.V2-V6;T1>T3 -N
Rhythm disturbance: not detected
NOTE: SV2+RV5=3.96
CONCLUSION: Sinus rhythm, regular. Horizontal position of the EOS. Signs of LV hypertrophy
Answers Bugaev Mikhail Valentinovich:
Hello. It is impossible to reliably determine the potassium content in the blood using an ECG (especially without seeing the film). You just need to go and take a blood test to determine your blood electrolyte levels. QT is a bit long.
2010-06-08 14:39:38
Irina asks:
Good afternoon Please decipher the results of the ECG, I am 19 years old, height 163, weight 68. Sinus rhythm, horizontal position of the EOS, diffuse changes in the myocardium, pain expressed in the anteroseptal region of the left ventricle. Measurement results: HR 86 beats\min, QRS 94, QT\QTcB 388\464, PQ 164, P 110, RR\PP 698\685, P\QRS\T 70\5\40, QTD\QTcBD 78\93, Sokolov 1.9, NK 12
2009-09-02 15:29:19
Lolita Shemetova asks:
Hello! My husband is 55 years old. In August of this year, he was examined at the Department of Invasive Cardiology and Angiology" Clinical hospital named after N.A. Semashko" in Simferopol, where he was given a CLINICAL DIAGNOSIS:
Myocardiofibrosis. Sick sinoantrial node syndrome. Transient SA blockade, stage II. Paroxysmal form of atrial fibrillation; group supraventricular extrasystole; unsustained atrial tachycardia. CH I st.
RELATED: Peptic ulcer stomach, remission.
results laboratory research:
12
GENERAL BLOOD ANALYSIS: Er. - 4.0 x 10 /l; Hb - 131 g/l; CPU-0.98;
9 9
Leu - 7.3x10 /l; Platelets - 250x10 /l; ESR - 12mm/h; e - 2%, p - 1%, s - 60%, l - 29%, m - 8%, Hematocrit - 0.42.
BIOCHEMICAL BLOOD TEST: Glucose - 3.8 mm/l; Total bilirubin - 15.0 mm/l; straight - 5.0 mm/l; indirect - 10.0 mm/l; Urea - 5.7 mmol/l; Urea nitrogen - 2.6 mmol/l;
Sodium - 136 mmol/l; Potassium - 3.85 mmol/l; Creatinine - 0.10 mmol/l; AST - 0.61 mmol/l; ALT - 0.44 mmol/l; Cholesterol - 6.0 mmol/l.
COAGULOGRAM:
Prothrombin index - 100%, fibrinogen A - 2.2 g/l,
fibrinogen B - 0 g/l; recalcification time - 1 minute; fibrin - 10 mg; Thrombotest - VI stage; Time St. according to Lee-White - 8 min. 34 sec; Ethanol test - 0.
GENERAL URINE ANALYSIS: Color - yellow; Relative density - 1020; Reaction - sour; Protein - not detected; Glucose - negative; Epithelium - 0-1 in the field of vision, transition - 0-1 in the field of view; Leukocytes - units in p/zr; Red blood cells - 0--1 in p/z.
BLOOD GROUP: O (1) RH: positive.
RW dated 08/18/2009
ELECTROCARDIOGRAM dated August 17, 2009: Sinus rhythm. Horizontal position of the EOS. Group supraventricular extrasystole.
RG OGK No. 334 dated August 11, 2009: No focal or infiltrative shadows were identified. The roots are wide and dense. The heart is slightly enlarged due to the left ventricle, the aorta is elongated.
Heart ultrasound dated August 11, 2009: LA - 3.6 cm; LV EDR - 6.2 cm; LV ESD - 4.4 cm; LV ZS - 0.9 cm; IVS - 1.0 cm; Ejection fraction - 55%; RV - 3.6 cm.
Conclusion: Congenital compacted additional chord in the LV cavity. Dilatation of the left ventricle, volume overload at the time of examination, eccentric hypertrophy of the left ventricle, myocardial factor is normal. Systolic and diastolic function were not changed. Septal fibrosis, fibrosis of the ring, walls of the non-expanded aortic root. Thrombus, non-classical anterior mitral and septal leaflet of the tricuspid valve, without obvious regurgitation. There is no pulmonary hypertension. The right sections are intact.
HM ECG dated 08/17/2009: Sinus rhythm alternates with frequent episodes of flutter - atrial fibrillation and unstable atrial tachycardia. Frequent episodes of SA - stage II blockade with a maximum pause of 1900 msec.
CORONAROGRAPHY from 08/17/2009: Atherosclerosis coronary arteries. No hemodynamically significant lesions of the coronary arteries were detected.
Treatment was carried out: sotohexal, ipatone, magne I6, kymacef + physical solution, afobazole.
DISCHARGE CONDITION: Satisfactory. No complaints.
Blood pressure 120/80 mmHg.
RECOMMENDATIONS:
1. Observation by a cardiologist at the place of residence.
2. Sotohexal 40 mg 2 times a day.
3. Ipaton 0.25 g 2 times a day.
4. Magne B6 - 1 t 2 times a day.
5. Afobazole 1 t 3 times a day - 1 month.
6. Bilobil 1 caps 3 times a day - 1 month.
7. Vestibo 16 mg 3 times a day - 1 month.
8. Repeat Holter monitoring after 1.5 - 2 months
subsequent consultation in the department of invasive cardiology and
angiology.
Sorry for such an extensive description, I don’t know if it’s appropriate.
The clinic’s specialists recommended that we prepare for the fact that my husband would have to have a pacemaker installed.
I in no way question their recommendations, but I would like to hear the opinions of other specialists, how necessary is this and are there other methods of treatment for this diagnosis? And if you are going to install a pacemaker, which of the two-chamber models is better to give preference to be able to conduct full image life, which does not exclude physical activity, leisure etc.
In Simferopol they offer pacemakers "Rhapsody" and "Symphony" made in France. But, they say, there are also more expensive models of pacemakers that are more multifunctional. What benefits do they provide?
I would be grateful and sincerely grateful for your answer.
Answers Selyuk Maryana Nikolaevna:
Good afternoon, Lolita
As for pacemakers, it is necessary, first of all, to decide whether it will be single-chamber or dual-chamber. Single-chamber pacemakers are a medical device that can affect and generate only one chamber of the heart (atrium or ventricle). Such pacemakers are the most simplified. The device can be frequency-controlled, in other words, it mechanically improves the frequency during physical exercise and without frequency regulation, that is, it continuously generates at the set frequency. Nowadays, single-chamber pacemakers are used to generate the right ventricle with chronic form atrial fibrillation, and in addition to the generation of the right atrium in sick sinus syndrome (SSNS). For other indicators, a two-chamber pacemaker is used (often also used for SSSS syndrome).
There are a huge number of both single- and double-chamber ones. Sometimes they differ only in price. But this question will be better answered by the cardiac surgeon who is examining your husband (it is necessary to take into account a number of absolutely specific parameters, both your husband and you should rely on clinical experience cardiac surgeon with certain pacemakers and the ability to perform a particular operation). But, you should pay attention to the indicators that I have highlighted in bold. With such cholesterol, the disease progresses quite quickly... Low sugar levels are also not good indicator. And the PTI indicator is high for your case. And the main thing - the phrase upon discharge - the condition is satisfactory, there are no complaints. So, all of the above stopped occurring (i.e., a cure occurred), or was the patient simply tired of complaining......?
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 anglefrom +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) - anglemore 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 anglefrom +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.
