Displacement of the heart. How to determine the position of the electrical axis

Cardiac activity. Many patients experience a shift electrical axis– shift either to the right or to the left. How to determine its position, what affects the change in EOS, and why is such a pathology dangerous?

Electrocardiography as a method for determining EOS

Electrocardiography is used to record the electrical activity of the heart in cardiology. Result this study is displayed in the form of a graphic recording and is called an electrocardiogram.

The procedure for taking an electrocardiogram is painless and takes about ten minutes. First, electrodes are applied to the patient, having previously lubricated the surface of the skin with a conductive gel or placed gauze pads soaked in saline solution.

Electrodes are applied in the following sequence:

on right wrist- red
on left wrist- yellow
on the left ankle - green
on the right ankle – black

Then six chest electrodes are applied, also in a certain sequence, from the middle of the chest to the left armpit. The electrodes are secured with a special tape or attached to suction cups.

The doctor turns on the electrocardiograph, which records the voltage between the two electrodes. The electrocardiogram is displayed on thermal paper and reflects the following parameters of the work and condition of the heart:

myocardial contraction frequency
systematic heartbeat
physical
heart muscle damage
disturbance of electrolyte metabolism
cardiac conduction disturbance, etc.

One of the main electrocardiological indicators is the direction of the electrical line of the heart. This parameter allows you to detect changes in cardiac activity or dysfunction of other organs (lungs, etc.).

Electrical axis of the heart: definition and influencing factors

To determine the electrical line of the heart important has a cardiac conduction system. This system consists of cardiac conductive muscle fibers that transmit electrical stimulation from one part of the heart to another.

Shift the electrical axis to the left

The electrical axis is strongly deflected to the left if its value is in the range from 0⁰ to -90⁰. This deviation can be caused by the following:

disturbances in impulse conduction along the left branch of His fibers (that is, in the left ventricle)
cardiosclerosis (a disease in which connective tissue replaces muscle tissue hearts)
persistent hypertension
heart defects
cardiomyopathy (changes in the heart muscle)
in the myocardium (myocarditis)
non-inflammatory myocardial damage (myocardial dystrophy)
intracardiac calcification and others

Shift of the electrical axis to the right side

An EOS value in the range from +90⁰ to +180⁰ indicates a strong deviation of the electrical axis of the heart to the right. The reasons for this change in the position of the heart axis may be:

Impaired impulse transmission right branch His fibers (responsible for the transmission of excitation in the right ventricle)
narrowing pulmonary artery(stenosis), which prevents the movement of blood from the right ventricle, so inside it
ischemic disease in combination with stand arterial hypertension(coronary disease is based on lack of myocardial nutrition)
myocardial infarction (death of myocardial cells of the right ventricle)
diseases of the bronchi and lungs that form " cor pulmonale" In this case, the left ventricle does not function fully, and congestion occurs in the right ventricle
pulmonary embolism, i.e. blockage of a vessel by a thrombus, resulting in a violation of gas exchange in the lungs, narrowing of small vessels blood circle and congestion of the right ventricle
stenosis mitral valve(most often occurs after rheumatism) - fusion of the valve leaflets, preventing the movement of blood from the left atrium, which leads to pulmonary hypertension and increased load on the right ventricle

The main consequence of all causes is increased load to the right ventricle. As a result, the walls of the right ventricle and the electrical vector of the heart deviate to the right.

Danger of changing the position of the EOS

Studying the direction of the electrical line of the heart is additional, so making a diagnosis based only on the location of the EOS is incorrect. If the patient is found to have a displacement of the EOS outside the normal range, comprehensive examination and the cause is identified, only then treatment is prescribed.

A concept that reflects electrical processes in this organ. The direction of the EOS shows all the bioelectric changes in total that occur during the work of the heart muscle. During the recording of an electrocardiogram, each electrode records the bioelectric reaction in a strictly designated part of the myocardium. Then, to calculate the position and angle of the EOS, doctors represent the chest in the form of a coordinate system in order to subsequently project the indicators of the electrodes onto it. Horizontal position of the EOS, vertical and a number of other options are possible.

The importance of the cardiac conduction system for EOS

The conduction system of the heart muscle is atypical muscle fibers that connect various parts of the organ and help it contract synchronously. Its beginning is considered to be the sinus node, located between the mouths of the vena cava, therefore in healthy people heart rate sinus. When in sinus node an impulse occurs, the myocardium contracts. If the conduction system malfunctions, the electrical axis changes its position, since this is where all the changes occur before the contraction of the heart muscle.

Axis directions and offset

Since the weight of the left ventricle of the heart muscle in completely healthy adults is greater than the right one, all electrical processes occur more strongly there. Therefore, the axis of the heart is directed towards it.

Normal position. If we project the location of the heart onto the expected coordinate system, then the direction of the left ventricle from +30 to +70 degrees will be considered normal. But it depends on the characteristics of each person, so the norm for this indicator is different people The range is considered to be from 0 to +90 degrees.
Horizontal position(from 0 to +30 degrees). Displayed on the cardiogram in short people with a wide sternum.
Vertical position. EOS ranges from +70 to +90 degrees. It is observed in tall people with a narrow chest.

There are diseases in which the axis shifts:

Deviation to the left. If the axis deviates to the left, this may indicate enlargement (hypertrophy) of the left ventricle, which indicates its overload. This condition is often caused by arterial hypertension, which occurs long time when blood has difficulty passing through the vessels. As a result, the left ventricle works harder. Deviation to the left occurs with various blockades and lesions of the valve apparatus. With progressive heart failure, when the organ cannot fully perform its functions, the electrocardiogram also records a shift of the axis to the left. All these diseases force the left ventricle to work harder, so its walls become thicker, the impulse through the myocardium passes much worse, the axis deviates to the left.
Offset to the right. Deviation of the electrical axis of the heart to the right most often occurs when the right ventricle is enlarged, for example, if a person has heart disease. This may be cardiomyopathy, coronary disease, structural abnormalities of the heart muscle. Right deviation also causes such problems with respiratory system, such as pulmonary obstruction, bronchial asthma.

EOS norm indicators

So, in healthy people, the direction of the heart axis can be normal, horizontal, vertical, the heart rhythm can be regular sinus. If the rhythm is not sinus, then this indicates some kind of disease. Irregular sinus rhythm is an indicator of the disease if it persists during breath holding. A shift of the cardiac axis to the left or right may indicate

is a term that means the electrical activity of an organ, that is, the total indicator of its average vector during depolarization. This is an indicator of the electrical processes of the heart.

This concept is used in cardiology and in functional diagnostics. Determination of the direction of EOS is carried out using an ECG.

In the direction of the axis, the doctor determines the bioelectric changes that occur in the myocardium during contraction.

To determine the direction of the EOS, there is a coordinate system that is located throughout chest.

With electrocardiography, the doctor can install the electrodes according to the coordinate system, and it will be clear where the axis angle is located, that is, the places where the electrical impulses are strongest.

Impulses travel along. It consists of atypical fibers that are located in certain areas of the organ.

This system begins in the sinus node. The impulse then passes to the atria and ventricles and to the bundle of His.

When any disturbances occur in the conduction system, the EOS changes its direction.

Axis location

U 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.

Regarding individual characteristics, then they note that in people who are tall and have 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 sharp deviation left or right.

Reasons for rejection

When the EOS deviates sharply to the left, this may mean that there is 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.

Regarding pathological deviation the axis of the heart 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 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.

It can be concluded that the main reason pathological displacement 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

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.

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 serious illnesses cardiological nature.

The figure below shows the six-axis Bailey lead system, which shows the red vector electrical axis of the heart located horizontally (angle α=0..+30°). The dotted line marks the projections of the e.o.s. vector. on the lead axis. Explanations for the figure are given in the table below.

On the "Automatic detection of EOS" page, a specially developed script will help you determine the location of the EOS based on ECG data from any two different leads.

Signs of horizontal position of the electrical axis of the heart

Lead	Amplitude and shape of the tooth
Standard lead I	E.o.s. is located as parallel as possible to lead I of all standard leads, therefore the projection of the e.o.s. on the axis of this lead will be the greatest, therefore, the amplitude of the R wave in this lead will be the maximum of all standard leads: R I >R II >R III
Standard lead II	E.o.s. is located in relation to axis II of the standard lead at an angle of 30..60°, therefore the amplitude of the R wave in this lead will be intermediate: R I >R II >R III
Standard lead III	Projection e.o.s. on axis III of the standard lead is as close as possible to the perpendicular, but still somewhat different from it, therefore, a small predominant negative wave will be recorded in this lead (since the e.o.s. is projected onto the negative part of the lead): S III >R III
Enhanced lead aVR	The enhanced lead aVR is located towards the e.o.s. the most parallel of all reinforced leads, while the e.o.s. vector is projected onto the negative part of this lead, therefore, in lead aVR a negative wave of the maximum amplitude of all enhanced leads will be recorded, approximately equal to the amplitude of the R wave in standard lead I: S aVR ≈R I
Enhanced lead aVL	E.o.s. is located in the area of the bisector of the angle formed by the standard lead II (positive half) and the enhanced lead aVL (positive half), hence the projection of the e.o.s. on the axis of these leads will be approximately the same: R aVL ≈R II
Enhanced lead aVF	The axis of the heart is vaguely perpendicular to lead aVF and is projected onto the positive part of the axis of this lead, therefore a small predominant positive wave will be recorded in this lead: R aVF >S aVF

Signs of horizontal position of e.o.s. ( angle α=0°)

Lead	Amplitude and shape of the tooth
Standard lead I	E.O.S direction coincides with the location of axis I of the standard lead and is projected onto its positive part. Therefore, the positive R wave has the maximum amplitude among all limb leads: R I =max>R II >R III
Standard lead II	E.o.s. identically located in relation to standard leads II and III: at an angle of 60° and projected onto the positive half of lead II and the negative half of the axis of lead III: R I >R II >R III ; S III >R III
Standard lead III
Enhanced lead aVR	E.o.s. identically located in relation to the enhanced leads aVR and aVL: at an angle of 30° and is projected onto the negative half of lead aVR and the positive half of aVL: S aVR =R aVL
Enhanced lead aVL
Enhanced lead aVF	Projection e.o.s. on the axis of the enhanced lead aVF is equal to zero (since the e.o.s. vector is perpendicular to this lead) - the amplitude of the positive R wave is equal to the amplitude of the negative S wave: R aVF =S aVF

ATTENTION! Information provided on the site website is for reference only. The site administration is not responsible for possible negative consequences in case of taking any medications or procedures without a doctor’s prescription!

Electrical axis of the heart is the average direction of the electromotive axis of the heart over the entire period of depolarization. The usual direction corresponds to + 59, but also healthy heart a deviation in the location of the electrical axis is possible on a scale from + 20 to + 100. Deviation of the electrical axis of the heart to the right is observed when the heart physically moves to the right and this indicates hypertrophy of the right cardiac ventricle or that the left ventricle has lost its activity.

What kind of phenomenon is this and how can you determine whether there is a deviation of the electrical axis?

The position of the axis is determined by the state of the His bundle and the cardiac ventricular muscle. This is influenced to some extent by the position of the heart. By correct position The electrical axis is located from the apex to the base, almost parallel to the anatomical axis of the heart. The direction of the axis depends on the following factors:

Location of the heart in the chest;

The relationship between the mass of the ventricular myocardium;

Focal myocardial lesions;

Disturbances in the conduction of impulses to the ventricles.

The electrical axis of the heart moves to the right side in the following cases:

In people of asthenic type;

With pulmonary embolism;

With hypertrophy of the right ventricular myocardium. Here the heart deviates to the right for some reason. First of all, in the hypertrophic ventricle the excitation of an additional number of fibers is very high and therefore its electrical potential has increased. It also takes longer to excite the ventricle compared to the norm. Therefore, the normal ventricle depolarizes much earlier in time than the hypertrophied ventricle, since it remains electropositive;

For congenital heart defects.

You should know these factors:

If the heart axis is deviated to the right in newborns, then there is no pathology. And this condition cannot be considered as right ventricular hypertrophy, since in newborn babies a deviation angle of +100 is a common phenomenon. Many children have this manifestation in the first months of life, especially those who live in areas with harsh climates and in high mountains. Deviation to the right occurs in small children with blockade of the left posterior branch of the His bundle.