What does ecg mean? Electrocardiogram: interpretation of results and indications for implementation. Normal sinus rhythm

Electrocardiography is a method of graphically recording the potential difference in the electrical field of the heart that arises during its activity. Registration is carried out using a device - an electrocardiograph. It consists of an amplifier that allows it to capture currents of very low voltage; a galvanometer that measures voltage; power systems; recording device; electrodes and wires connecting the patient to the device. The waveform that is recorded is called an electrocardiogram (ECG). Registration of the potential difference in the electric field of the heart from two points on the surface of the body is called lead. As a rule, the ECG is recorded in twelve leads: three bipolar (three standard leads) and nine unipolar (three unipolar enhanced limb leads and 6 unipolar chest leads). With bipolar leads, two electrodes are connected to the electrocardiograph; with unipolar leads, one electrode (indifferent) is combined, and the second (different, active) is placed at a selected point on the body. If the active electrode is placed on a limb, the lead is called unipolar, limb-amplified; if this electrode is placed on the chest - with a unipolar chest lead.

To record an ECG in standard leads (I, II and III), cloth napkins moistened with saline are placed on the limbs, on which metal electrode plates are placed. One electrode with a red wire and one raised ring is placed on the right, the second - with a yellow wire and two raised rings - on the left forearm, and the third - with a green wire and three raised rings - on the left shin. To record leads, two electrodes are connected to the electrocardiograph in turn. To record lead I, the electrodes of the right and left hands are connected, lead II - electrodes of the right hand and left leg, lead III - electrodes of the left hand and left leg. Switching leads is done by turning the knob. In addition to the standard ones, unipolar reinforced leads are removed from the limbs. If the active electrode is located on the right arm, the lead is designated as aVR or UP, if on the left arm - aVL or UL, and if on the left leg - aVF or UL.

Rice. 1. The location of the electrodes when registering the anterior chest leads (indicated in numbers corresponding to their serial numbers). The vertical stripes crossing the numbers correspond to the anatomical lines: 1 - right sternal; 2 - left sternal; 3 - left parasternal; 4-left midclavicular; 5-left anterior axillary; 6 - left middle axillary.

When recording unipolar chest leads, the active electrode is placed on the chest. The ECG is recorded in the following six electrode positions: 1) at the right edge of the sternum in the IV intercostal space; 2) at the left edge of the sternum in the IV intercostal space; 3) along the left parasternal line between the IV and V intercostal spaces; 4) along the midclavicular line in the 5th intercostal space; 5) along the anterior axillary line in the 5th intercostal space and 6) along the middle axillary line in the 5th intercostal space (Fig. 1). Unipolar chest leads are designated by the Latin letter V or in Russian - GO. Less commonly recorded are bipolar chest leads, in which one electrode is located on the chest and the other on the right arm or left leg. If the second electrode was located on the right arm, the chest leads were designated by the Latin letters CR or Russian - GP; when the second electrode was located on the left leg, the chest leads were designated by the Latin letters CF or Russian - GN.

The ECG of healthy people is variable. It depends on age, physique, etc. However, normally it is always possible to distinguish certain teeth and intervals on it, reflecting the sequence of excitation of the heart muscle (Fig. 2). According to the available time stamp (on photographic paper the distance between two vertical stripes is 0.05 sec, on graph paper at a broaching speed of 50 mm/sec 1 mm is 0.02 sec, at a speed of 25 mm/sec - 0.04 sec. ) you can calculate the duration of ECG waves and intervals (segments). The height of the teeth is compared with a standard mark (when a voltage pulse of 1 mV is applied to the device, the recorded line should deviate from the original position by 1 cm). Excitation of the myocardium begins from the atria, and the atrial P wave appears on the ECG. Normally, it is small: 1-2 mm high and lasting 0.08-0.1 seconds. The distance from the beginning of the P wave to the Q wave (P-Q interval) corresponds to the time of propagation of excitation from the atria to the ventricles and is equal to 0.12-0.2 seconds. During excitation of the ventricles, the QRS complex is recorded, and the size of its waves in different leads is expressed differently: the duration of the QRS complex is 0.06-0.1 seconds. The distance from the S wave to the beginning of the T wave - the S-T segment, is normally located at the same level with the P-Q interval and its displacement should not exceed 1 mm. When excitation in the ventricles fades, a T wave is recorded. The interval from the beginning of the Q wave to the end of the T wave reflects the process of excitation of the ventricles (electrical systole). Its duration depends on the heart rate: when the rhythm increases, it shortens, when it slows down, it lengthens (on average it is 0.24-0.55 seconds). The heart rate can be easily calculated from an ECG, knowing how long one cardiac cycle lasts (the distance between two R waves) and how many such cycles are contained in a minute. The T-P interval corresponds to the diastole of the heart; at this time the device records a straight (so-called isoelectric) line. Sometimes after the T wave a U wave is recorded, the origin of which is not entirely clear.

Rice. 2. Electrocardiogram of a healthy person.

In pathology, the size of the waves, their duration and direction, as well as the duration and location of ECG intervals (segments), can vary significantly, which gives rise to the use of electrocardiography in the diagnosis of many heart diseases. Using electrocardiography, various heart rhythm disturbances are diagnosed (see), inflammatory and dystrophic lesions of the myocardium are reflected on the ECG. Electrocardiography plays a particularly important role in the diagnosis of coronary insufficiency and myocardial infarction.

Using an ECG, you can determine not only the presence of a heart attack, but also find out which wall of the heart is affected. In recent years, to study the potential difference in the electric field of the heart, the method of teleelectrocardiography (radioelectrocardiography), based on the principle of wireless transmission of the electric field of the heart using a radio transmitter, has been used. This method allows you to register an ECG during physical activity, in motion (for athletes, pilots, astronauts).

Electrocardiography (Greek kardia - heart, grapho - writing, recording) is a method of recording electrical phenomena occurring in the heart during its contraction.

The history of electrophysiology, and therefore electrocardiography, begins with the experiment of Galvani (L. Galvani), who discovered electrical phenomena in the muscles of animals in 1791. Matteucci (S. Matteucci, 1843) established the presence of electrical phenomena in an excised heart. Dubois-Reymond (E. Dubois-Reymond, 1848) proved that in both nerves and muscles the excited part is electronegative relative to the resting part. Kolliker and Muller (A. Kolliker, N. Muller, 1855), applying a frog neuromuscular preparation consisting of a sciatic nerve connected to the gastrocnemius muscle to the contracting heart, obtained a double contraction during heart contraction: one at the beginning of systole and the other (non-constant ) at the beginning of diastole. Thus, the electromotive force (EMF) of the naked heart was recorded for the first time. Waller (A. D. Waller, 1887) was the first to record the EMF of the heart from the surface of the human body using a capillary electrometer. Waller believed that the human body is a conductor surrounding the source of EMF - the heart; different points of the human body have potentials of different magnitudes (Fig. 1). However, the recording of cardiac EMF obtained by a capillary electrometer did not accurately reproduce its fluctuations.

Rice. 1. Scheme of the distribution of isopotential lines on the surface of the human body, caused by the electromotive force of the heart. The numbers indicate the potential values.

An accurate recording of the EMF of the heart from the surface of the human body - an electrocardiogram (ECG) - was made by Einthoven (W. Einthoven, 1903) using a string galvanometer, built on the principle of devices for receiving transatlantic telegrams.

According to modern concepts, cells of excitable tissues, in particular myocardial cells, are covered with a semi-permeable membrane (membrane), permeable to potassium ions and impermeable to anions. Positively charged potassium ions, which are in excess in cells compared to their surrounding environment, are retained on the outer surface of the membrane by negatively charged anions located on its inner surface, impenetrable to them.

Thus, a double electrical layer appears on the shell of a living cell - the shell is polarized, and its outer surface is charged positively in relation to the internal contents, which are negatively charged.

This transverse potential difference is the resting potential. If microelectrodes are applied to the outer and inner sides of the polarized membrane, a current arises in the outer circuit. Recording the resulting potential difference gives a monophasic curve. When excitation occurs, the membrane of the excited area loses its semi-permeability, depolarizes, and its surface becomes electronegative. Registration of the potentials of the outer and inner shell of the depolarized membrane with two microelectrodes also gives a monophasic curve.

Due to the potential difference between the surface of the excited depolarized area and the surface of the polarized one, which is at rest, an action current arises - an action potential. When excitation covers the entire muscle fiber, its surface becomes electronegative. The cessation of excitation causes a wave of repolarization, and the resting potential of the muscle fiber is restored (Fig. 2).

Rice. 2. Schematic representation of polarization, depolarization and repolarization of a cell.

If the cell is at rest (1), then on both sides of the cell membrane there is an electrostatic equilibrium, consisting in the fact that the surface of the cell is electropositive (+) in relation to its inner side (-).

The excitation wave (2) instantly disrupts this balance, and the surface of the cell becomes electronegative with respect to its interior; This phenomenon is called depolarization or, more correctly, inversion polarization. After the excitation has passed through the entire muscle fiber, it becomes completely depolarized (3); its entire surface has the same negative potential. This new equilibrium does not last long, since the excitation wave is followed by a repolarization wave (4), which restores the polarization of the resting state (5).

The process of excitation in a normal human heart - depolarization - proceeds as follows. Arising in the sinus node, located in the right atrium, the excitation wave propagates at a speed of 800-1000 mm per 1 second. radially along the muscle bundles of first the right and then the left atrium. The duration of excitation coverage of both atria is 0.08-0.11 seconds.

The first 0.02 - 0.03 sec. Only the right atrium is excited, then 0.04 - 0.06 seconds - both atria and the last 0.02 - 0.03 seconds - only the left atrium.

Upon reaching the atrioventricular node, the spread of excitation slows down. Then, at a high and gradually increasing speed (from 1400 to 4000 mm per 1 second), it is directed along the bundle of His, its legs, their branches and branches and reaches the final ends of the conduction system. Having reached the contractile myocardium, excitation spreads through both ventricles at a significantly reduced speed (300-400 mm per 1 second). Since the peripheral branches of the conduction system are scattered mainly under the endocardium, the inner surface of the heart muscle is the first to become excited. The further course of excitation of the ventricles is not related to the anatomical location of the muscle fibers, but is directed from the inner surface of the heart to the outer. The time of excitation in the muscle bundles located on the surface of the heart (subepicardial) is determined by two factors: the time of excitation of the branches of the conduction system closest to these bundles and the thickness of the muscle layer separating the subepicardial muscle bundles from the peripheral branches of the conduction system.

The interventricular septum and the right papillary muscle are the first to be excited. In the right ventricle, excitation first covers the surface of its central part, since the muscle wall in this place is thin and its muscle layers are in close contact with the peripheral branches of the right leg of the conduction system. In the left ventricle, the apex is the first to become excited, since the wall separating it from the peripheral branches of the left leg is thin. For various points on the surface of the right and left ventricles of a normal heart, the period of excitation begins at a strictly defined time, and most of the fibers on the surface of the thin-walled right ventricle and only a small number of fibers on the surface of the left ventricle become excited first due to their proximity to the peripheral branches of the conduction system (Fig. .3).

Rice. 3. Schematic representation of normal excitation of the interventricular septum and outer walls of the ventricles (according to Sodi-Pallares et al.). Excitation of the ventricles begins on the left side of the septum in its middle part (0.00-0.01 sec.) and then can reach the base of the right papillary muscle (0.02 sec.). After this, the subendocardial muscle layers of the outer wall of the left (0.03 sec.) and right (0.04 sec.) ventricles are excited. The last to be excited are the basal parts of the outer walls of the ventricles (0.05-0.09 sec.).

The process of cessation of excitation of the muscle fibers of the heart - repolarization - cannot be considered fully studied. The process of atrial repolarization coincides for the most part with the process of depolarization of the ventricles and partly with the process of their repolarization.

The process of ventricular repolarization is much slower and in a slightly different sequence than the process of depolarization. This is explained by the fact that the duration of excitation of the muscle bundles of the superficial layers of the myocardium is less than the duration of excitation of the subendocardial fibers and papillary muscles. Recording the process of depolarization and repolarization of the atria and ventricles from the surface of the human body gives a characteristic curve - an ECG, reflecting the electrical systole of the heart.

The EMF of the heart is currently recorded using slightly different methods than those recorded by Einthoven. Einthoven recorded the current generated by connecting two points on the surface of the human body. Modern devices - electrocardiographs - directly record the voltage caused by the electromotive force of the heart.

The voltage caused by the heart, equal to 1-2 mV, is amplified by radio tubes, semiconductors or a cathode ray tube to 3-6 V, depending on the amplifier and recording apparatus.

The sensitivity of the measuring system is set so that a potential difference of 1 mV gives a deviation of 1 cm. Recording is done on photographic paper or film or directly on paper (ink, thermal recording, inkjet recording). The most accurate results are obtained by recording on photographic paper or film and inkjet recording.

To explain the peculiar shape of the ECG, various theories of its genesis have been proposed.

A.F. Samoilov considered the ECG as the result of the interaction of two monophasic curves.

Considering that when two microelectrodes record the outer and inner surfaces of the membrane in states of rest, excitation and damage, a monophasic curve is obtained, M. T. Udelnov believes that the monophasic curve reflects the main form of bioelectrical activity of the myocardium. The algebraic sum of two monophasic curves gives the ECG.

Pathological ECG changes are caused by shifts in monophasic curves. This theory of the genesis of the ECG is called differential.

The outer surface of the cell membrane during the period of excitation can be represented schematically as consisting of two poles: negative and positive.

Immediately before the excitation wave at any point in its propagation, the cell surface is electropositive (resting state of polarization), and immediately after the excitation wave, the cell surface is electronegative (depolarization state; Fig. 4). These electric charges of opposite signs, grouped in pairs on one side and the other of each place covered by the excitation wave, form electric dipoles (a). Repolarization also creates an innumerable number of dipoles, but unlike the above dipoles, the negative pole is in front and the positive pole is behind in relation to the direction of wave propagation (b). If depolarization or repolarization is complete, the surface of all cells has the same potential (negative or positive); dipoles are completely absent (see Fig. 2, 3 and 5).

Rice. 4. Schematic representation of electric dipoles during depolarization (a) and repolarization (b), arising on both sides of the excitation wave and the repolarization wave as a result of changes in the electrical potential on the surface of the myocardial fibers.

Rice. 5. Diagram of an equilateral triangle according to Einthoven, Faro and Warth.

The muscle fiber is a small bipolar generator that produces a small (elementary) EMF - an elementary dipole.

At each moment of cardiac systole, depolarization and repolarization occurs of a huge number of myocardial fibers located in different parts of the heart. The sum of the resulting elementary dipoles creates the corresponding value of the EMF of the heart at each moment of systole. Thus, the heart represents, as it were, one total dipole, changing its magnitude and direction during the cardiac cycle, but not changing the location of its center. The potential at different points on the surface of the human body has different values ​​depending on the location of the total dipole. The sign of the potential depends on which side of the line perpendicular to the dipole axis and drawn through its center the given point is located: on the side of the positive pole the potential has a + sign, and on the opposite side it has a - sign.

Most of the time the heart is excited, the surface of the right half of the torso, right arm, head and neck has a negative potential, and the surface of the left half of the torso, both legs and left arm has a positive potential (Fig. 1). This is a schematic explanation of the genesis of the ECG according to the dipole theory.

The EMF of the heart during electrical systole changes not only its magnitude, but also its direction; therefore, it is a vector quantity. A vector is depicted as a straight line segment of a certain length, the size of which, given certain data from the recording apparatus, indicates the absolute value of the vector.

The arrow at the end of the vector indicates the direction of the cardiac EMF.

The EMF vectors of individual heart fibers that arise simultaneously are summed up according to the vector addition rule.

The total (integral) vector of two vectors located parallel and directed in one direction is equal in absolute value to the sum of its constituent vectors and is directed in the same direction.

The total vector of two vectors of the same magnitude, located parallel and directed in opposite directions, is equal to 0. The total vector of two vectors directed to each other at an angle is equal to the diagonal of a parallelogram constructed from its constituent vectors. If both vectors form an acute angle, then their total vector is directed towards its constituent vectors and is greater than any of them. If both vectors form an obtuse angle and, therefore, are directed in opposite directions, then their total vector is directed towards the largest vector and is shorter than it. Vector analysis of an ECG consists of determining from the ECG waves the spatial direction and magnitude of the total EMF of the heart at any moment of its excitation.

Cardiovascular diseases are one of the leading causes of death among people worldwide. Over the past decades, this figure has decreased significantly due to the advent of more modern methods of examination, treatment, and, of course, new medications.

Electrocardiography (ECG) is a method of recording the electrical activity of the heart, one of the first research methods, which for a long time remained practically the only one in this field of medicine. About a century ago, in 1924, Willem Einthoven received the Nobel Prize in Medicine; he designed the apparatus with which the ECG was recorded, named its waves, and identified the electrocardiographic signs of certain heart diseases.

Many research methods are losing their relevance with the advent of more modern developments, but this does not apply to electrocardiography. Even with the advent of imaging techniques (CT, CT, etc.), the ECG for decades continues to be the most common, very informative, and in some places the only available method for studying the heart. Moreover, over the century of its existence, neither the device itself nor the method of its use have changed significantly.

Indications and contraindications

A person may be prescribed an ECG for the purpose of preventive examination, as well as if any heart disease is suspected.

Electrocardiography is a unique examination method that helps make a diagnosis or becomes a starting point for drawing up a plan for further examination of the patient. In any case, the diagnosis and treatment of any heart disease begins with an ECG.

An ECG is an absolutely safe and painless method of examination for people of all ages; there are no contraindications to conventional electrocardiography. The study takes only a few minutes and does not require any special preparation.

But there are so many indications for electrocardiography that it is simply impossible to list them all. The main ones are the following:

• general examination during medical examination or medical commission;
• assessment of the state of the heart in various diseases (atherosclerosis, lung diseases, etc.);
• differential diagnosis for chest pain and (often have a non-cardiac cause);
• suspicion of, as well as control of the course of this disease;
• diagnosis of heart rhythm disorders (24-hour Holter ECG monitoring);
• disturbance of electrolyte metabolism (hyper- or hypokalemia, etc.);
• overdose of drugs (for example, cardiac glycosides or antiarrhythmic drugs);
• diagnosis of non-cardiac diseases (pulmonary embolism), etc.

The main advantage of an ECG is that the study can be performed outside a hospital; many ambulances are equipped with electrocardiographs. This allows the doctor at the patient’s home to detect myocardial infarction at its very beginning, when damage to the heart muscle is just beginning and is partially reversible. After all, treatment in such cases begins while the patient is being transported to the hospital.

Even in cases where the emergency room is not equipped with this device and the emergency doctor does not have the opportunity to perform the study at the prehospital stage, the first diagnostic method in the emergency room of a medical institution will be an ECG.

Interpretation of ECG in adults

In most cases, cardiologists, therapists, and emergency doctors work with electrocardiograms, but a specialist in this field is a functional diagnostics doctor. Interpreting an ECG is not an easy task, which is beyond the power of a person who does not have the appropriate qualifications.

Typically, on the ECG of a healthy person, five waves can be distinguished, recorded in a certain sequence: P, Q, R, S and T, sometimes a U wave is recorded (its nature is not exactly known today). Each of them reflects the electrical activity of the myocardium in different parts of the heart.

When recording an ECG, several complexes corresponding to heart contractions are usually recorded. In a healthy person, all the teeth in these complexes are located at the same distance. The difference in the intervals between complexes indicates.

In this case, in order to accurately determine the form of the arrhythmia, Holter ECG monitoring may be necessary. Using a special small portable device, the cardiogram is recorded continuously for 1-7 days, after which the resulting recording is processed using a computer program.

• The first P wave reflects the process of depolarization (excitation coverage) of the atria. Based on its width, amplitude and shape, the doctor can suspect hypertrophy of these chambers of the heart, a disturbance in the conduction of impulses through them, and suggest that the patient has organ defects and other pathologies.
• The QRS complex reflects the process of excitation of the ventricles of the heart. Deformation of the shape of the complex, a sharp decrease or increase in its amplitude, the disappearance of one of the teeth can indicate a variety of diseases: myocardial infarction (with the help of an ECG you can determine its location and duration), scars, conduction disorders (bundle branch block), etc.
• The last T wave is determined by ventricular repolarization (relatively speaking, relaxation); deformation of this element can indicate electrolyte disturbances, ischemic changes and other heart pathologies.

The ECG sections connecting different waves are called “segments”. Normally, they lie on the isoline, or their deviation is not significant. Between the teeth there are intervals (for example, PQ or QT), which reflect the time of passage of the electrical impulse through the parts of the heart; in a healthy person they have a certain duration. Lengthening or shortening of these intervals is also a significant diagnostic sign. Only a qualified doctor can see and evaluate all changes on the ECG.

In deciphering an ECG, every millimeter is important, sometimes even half a millimeter is decisive in choosing treatment tactics. Very often, an experienced doctor can make an accurate diagnosis using an electrocardiogram without the use of additional research methods, and in some cases its information content exceeds the data of other types of research. In essence, this is a screening method of examination in cardiology, which allows one to identify or at least suspect heart disease in the early stages. That is why the electrocardiogram will remain one of the most popular diagnostic methods in medicine for many years to come.

Which doctor should I contact?

For a referral for an ECG, you need to contact a physician or cardiologist. The analysis of the cardiogram and the conclusion on it are given by a functional diagnostics doctor. The ECG report itself is not a diagnosis and must be considered by the clinician in combination with other data about the patient.

Basics of electrocardiography in educational video:

Video course “Everyone can do an ECG”, lesson 1:

Video course “Everyone can do an ECG”, lesson 2.

An electrocardiogram (ECG) is an instrumental diagnostic method that determines pathological processes in the heart by recording cardiac electrical impulses. A graphical representation of the activity of the heart muscles under the influence of electrical impulses allows the cardiologist to timely identify the presence or development of cardiac pathologies.

ECG interpretation indicators help to determine with great certainty:

1. Frequency and rhythm of heart contraction;
2. Diagnose acute or chronic processes in the heart muscle in a timely manner;
3. Disorders of the conduction system of the heart and its independent rhythmic contractions;
4. See hypertrophic changes in its departments;
5. Identify disturbances in water-electrolyte balance and non-cardiac pathologies (cor pulmonale) throughout the body.

The need for an electrocardiographic examination is due to the manifestation of certain symptoms:

• the presence of synchronous or periodic heart murmurs;
• syncope signs (fainting, short-term loss of consciousness);
• attacks of convulsive seizures;
• paroxysmal arrhythmia;
• manifestations of coronary artery disease (ischemia) or infarction conditions;
• the appearance of pain in the heart, shortness of breath, sudden weakness, cyanosis of the skin in patients with cardiac diseases.

ECG studies are used to diagnose systemic diseases, monitor patients under anesthesia or before surgery. Before clinical examination of patients who have crossed the 45-year mark.

An ECG examination is mandatory for persons undergoing a medical examination (pilots, drivers, machinists, etc.) or associated with hazardous work.

The human body has high electrical conductivity, which allows the potential energy of the heart to be read from its surface. Electrodes connected to various parts of the body help with this. In the process of excitation of the heart muscle by electrical impulses, the voltage difference oscillates between certain lead points, which is recorded by electrodes located on the body - on the chest and limbs.

A certain movement and amount of tension during systole and diastole (contraction and relaxation) of the heart muscle changes, the tension fluctuates, and this is recorded on a chart paper tape with a curved line - teeth, convexity and concavity. Electrodes placed on the limbs (standard leads) create signals and form the tops of triangular teeth.

Six leads located on the chest display cardiac activity in a horizontal position - from V1 to V6.

On the limbs:

• Lead (I) – displays the voltage level in the intermediate circuit of the electrodes located on the left and right wrist (I=LR+PR).
• (II) – records on the tape the electrical activity in the circuit – ankle of the left leg + wrist of the right hand).
• Lead (III) – characterizes the voltage in the chain of fixed electrodes of the wrist of the left hand and ankle of the left leg (LR + LN).

If necessary, additional leads are installed, reinforced ones - “aVR”, “aVF” and “aVL”.

Interpretation of ECG diagram, photo

The general principles of deciphering a cardiac cardiogram are based on the readings of the elements of the cardiography curve on the chart tape.

The teeth and bulges on the diagram are indicated by capital letters of the Latin alphabet - “P”, “Q”, “R”, “S”, “T”

1. The convexity (wave or concavity) of the “P” reflects the function of the atria (their excitation), and the entire complex of the upward-pointing wave is the “QRS”, the greatest spread of the impulse through the cardiac ventricles.
2. The “T” convexity characterizes the restoration of the potential energy of the myocardium (the middle layer of the heart muscle).
3. When deciphering ECGs in adults, special attention is paid to the distance (segment) between adjacent elevations - “P-Q” and “S-T”, which reflect the delay of electrical impulses between the cardiac ventricles and the atrium, and the “TR” segment - relaxation of the heart muscle in the interval (diastole) .
4. The intervals on the cardiographic line include both elevations and segments. For example - “P-Q” or “Q-T”.

Each element in the graphic image indicates certain processes occurring in the heart. It is by the indicators of these elements (length, height, width), location relative to the isoline, features, according to the various locations of electrodes (leads) on the body that the doctor can identify the affected areas of the myocardium, based on the readings of the dynamic aspects of the energy of the heart muscle.

Interpretation of ECG - the norm in adults, table

The analysis of the ECG decoding result is carried out by assessing the data in a certain sequence:

• Determination of heart rate indicators. With the same interval between the “R” teeth, the indicators correspond to the norm.
• The heart rate is calculated. This is determined simply - the ECG recording time is distributed by the number of cells in the interval between the “R” teeth. With a good cardiogram of the heart, the frequency of contractions of the heart muscle should be within the limits not exceeding 90 beats/min. A healthy heart should have sinus rhythm, it is determined mainly by the elevation of “P”, reflecting the excitation of the atria. In terms of wave motion, this normal indicator is 0.25 mV with a duration of 100 ms.
• The norm for the size of the depth of the “Q” wave should not be more than 0.25% of the fluctuations in the elevation of “R” and the width of 30 ms.
• The latitude of oscillations of the “R” elevation, during normal heart function, can be displayed with a large range ranging from 0.5-2.5 mV. And the activation time of excitation above the zone of the right cardiac chamber - V1-V2 is 30 ms. Above the left chamber zone – V5 and V6, it corresponds to 50 ms.
• According to the maximum length of the “S” wave, its normal dimensions at the greatest abduction cannot cross the threshold of 2.5 mV.
• The amplitude of the oscillations of the “T” elevation, which reflects the restorative cellular processes of the initial potential in the myocardium, should be equal to ⅔ of the oscillations of the “R” wave. The normal interval (width) of the "T" elevation can vary (100-250) ms.
• The normal width of the ventricular excitation complex (QRS) is 100 ms. It is measured by the interval between the beginning of the “Q” and the end of the “S” teeth. The normal amplitude of the duration of the “R” and “S” waves is determined by the electrical activity of the heart. The maximum duration should be within 2.6 mV.

ECG decoding for adults norm in the table
Index	Meaning
QRS	0.06-0.1 s
P	0.07-0.11 s
Q	0.03 s
T	0.12-0.28 s
P.O.	0.12-0.2 s
Heart rate	60-80 beats minute

Interpretation of ECG in children, normal indicators

An electrocardiogram in children, as practice shows, is not much different from normal values ​​in adult patients. But certain physiological age-related characteristics can change some indicators. In particular, heart rate. In young children under 3 years old, they can range from 100 to 110 contractions/minute. But already at puberty, it is equal to adult indicators (60-90).

Normally, when deciphering an ECG of the heart in children, the passage of electrical impulses through the parts of the heart (in the range of elevations P, QRS, T) varies from 120 to 200 ms.

The ventricular excitation rate (QRS) is determined by the width of the interval between the “Q” and “S” waves and should not exceed the boundaries of 60-100 ms.

Particular attention is paid to the size (excitation activity) of the right ventricle (V1-V2). In children this figure is higher than in the left ventricle. With age, the indicators return to normal.

• Quite often, ECGs in children show thickening, splitting, or notching on the “R” elevations. Such a symptom in the cardiogram of adults indicates tachycardia and bradycardia, and in children it is a completely common condition.

But there are indications of a bad cardiogram hearts, which indicate the presence or progression of pathological processes in the heart. Much depends on the child’s individual performance. In addition, interruption or slowing of the normal heart rhythm occurs in children who experience chest pain, dizziness, and who often show signs of blood pressure instability or poor coordination.

If an ECG examination of a child reveals that the heart rate exceeds 110 beats/min. - this is an alarming signal indicating the development of tachycardia.

It is necessary to immediately reduce the child’s physical activity and protect him from nervous overexcitation. In children, such symptoms may be temporary, but if measures are not taken, tachycardia will develop into a permanent problem.

Example ECG - Atrial fibrillation

An electrocardiogram is the most accessible, common way to make a diagnosis, even in conditions of emergency intervention by an ambulance team.

Now every cardiologist in the visiting team has a portable and lightweight electrocardiograph, capable of reading information by recording on a recorder the electrical impulses of the heart muscle - the myocardium at the moment of contraction.

Anyone, even a child, can decipher an ECG, given the fact that the patient understands the basic canons of the heart. Those very teeth on the tape are the peak (response) of the heart to contraction. The more frequent they are, the faster the myocardial contraction occurs; the fewer there are, the slower the heartbeat occurs, and in fact the transmission of a nerve impulse. However, this is just a general idea.

To make a correct diagnosis, it is necessary to take into account the time intervals between contractions, the height of the peak value, the age of the patient, the presence or absence of aggravating factors, etc.

An ECG of the heart for diabetics who, in addition to diabetes mellitus, also have late cardiovascular complications, allows one to assess the severity of the disease and intervene in a timely manner in order to delay further progression of the disease, which can lead to serious consequences in the form of myocardial infarction, pulmonary embolism and etc.

If the pregnant woman had a bad electrocardiogram, then repeated studies are prescribed with possible daily monitoring.

However, it is worth considering the fact that the values ​​​​on the tape for a pregnant woman will be slightly different, since during the growth of the fetus there is a natural displacement of the internal organs, which are forced out by the expanding uterus. Their heart occupies a different position in the chest area, therefore, the electrical axis shifts.

In addition, the longer the period, the greater the load the heart experiences, which is forced to work harder in order to satisfy the needs of two full-fledged organisms.

However, you should not worry so much if the doctor reported the same tachycardia based on the results, since it is most often that it can be false, provoked either intentionally or out of ignorance by the patient himself. Therefore, it is extremely important to properly prepare for this study.

In order to pass the test correctly, you need to understand that any excitement, excitement and worry will inevitably affect the results. Therefore, it is important to prepare yourself in advance.

Not acceptable

1. Drinking alcohol or any other strong drinks (including energy drinks, etc.)
2. Overeating (best to take on an empty stomach or have a light snack before going out)
3. Smoking
4. Using drugs that stimulate or suppress heart activity or drinks (such as coffee)
5. Physical activity
6. Stress

There are often cases when a patient, being late for the treatment room at the appointed time, began to worry greatly or frantically rushed to the treasured room, forgetting about everything in the world. As a result, its leaf was riddled with frequent sharp teeth, and the doctor, of course, recommended that his patient undergo the test again. However, in order not to create unnecessary problems, try to calm yourself as much as possible before entering the cardiology room. Moreover, nothing bad will happen to you there.

When the patient is invited, it is necessary to undress to the waist behind a screen (for women, remove their bra) and lie down on the couch. In some treatment rooms, depending on the suspected diagnosis, it is also necessary to free the body from the torso down to the underwear.

After that, the nurse applies a special gel to the lead sites, to which electrodes are attached, from which multi-colored wires are stretched to the reading machine.

Thanks to special electrodes, which the nurse places at certain points, the slightest cardiac impulse is detected, which is recorded using a recorder.

After each contraction, called depolarization, a tooth is displayed on the tape, and at the moment of transition to a calm state - repolarization, the recorder leaves a straight line.

Within a few minutes, the nurse will take a cardiogram.

The tape itself, as a rule, is not given to patients, but is handed directly to the cardiologist who decrypts it. With notes and transcripts, the tape is sent to the attending physician or transferred to the reception desk so that the patient can pick up the results himself.

But even if you pick up a cardiogram tape, you will hardly be able to understand what is depicted there. Therefore, we will try to lift the veil of secrecy a little so that you can at least assess the potential of your heart.

ECG interpretation

Even on a blank sheet of this type of functional diagnostics there are some notes that help the doctor with decoding. The recorder reflects the transmission of an impulse that, over a certain period of time, passes through all parts of the heart.

To understand these scribbles, you need to know in what order and how exactly the impulse is transmitted.

The impulse, passing through different parts of the heart, is displayed on the tape in the form of a graph, which conventionally displays marks in the form of Latin letters: P, Q, R, S, T

Let's figure out what they mean.

P value

The electrical potential, going beyond the sinus node, transmits excitation primarily to the right atrium, in which the sinus node is located.

At this very moment, the reading device will record a change in the form of a peak of excitation of the right atrium. Then it passes through the conduction system - the interatrial bundle of Bachmann - into the left atrium. Its activity occurs at the moment when the right atrium is already fully engulfed in excitement.

On the tape, both of these processes appear as the total value of excitation of both atria of the right and left and are recorded as peak P.

In other words, the P peak is sinus excitation that travels along the pathways from the right to the left atrium.

Interval P - Q

Simultaneously with the excitation of the atria, the impulse that goes beyond the sinus node passes along the lower branch of the Bachmann bundle and enters the atrioventricular junction, which is otherwise called the atrioventricular junction.

There is a natural impulse delay here. Therefore, a straight line appears on the tape, which is called isoelectric.

In assessing the interval, the time it takes for the impulse to travel through this connection and subsequent sections plays a role.

Counting is done in seconds.

Complex Q, R, S

Afterwards, the impulse, passing along the conduction pathways in the form of the His bundle and Purkinje fibers, reaches the ventricles. This whole process is presented on the tape in the form of a QRS complex.

The ventricles of the heart are always excited in a certain sequence and the impulse travels this path in a certain amount of time, which also plays an important role.

Initially, the excitation covers the septum between the ventricles. This takes about 0.03 seconds. A Q wave appears on the diagram, extending just below the main line.

After the impulse for 0.05. sec. reaches the apex of the heart and adjacent areas. A tall R wave forms on the tape.

Then it moves to the base of the heart, which is reflected in the form of a falling S wave. This takes 0.02 seconds.

Thus, QRS is an entire ventricular complex with a total duration of 0.10 seconds.

S-T interval

Since myocardial cells cannot remain excited for a long time, a moment of decline occurs when the impulse fades away. By this time, the process of restoring the original state that reigned before the excitement begins.

This process is also recorded on the ECG.

By the way, in this matter the initial role is played by the redistribution of sodium and potassium ions, the movement of which gives this very impulse. All this is usually called in one word - the process of repolarization.

We will not go into details, but will only note that this transition from excitation to extinction is visible in the interval from S to T waves.

ECG normal

These are the basic designations, looking at which you can judge the speed and intensity of the heart muscle beat. But in order to get a more complete picture, it is necessary to reduce all the data to some single ECG standard. Therefore, all devices are configured in such a way that the recorder first draws control signals on the tape, and only then begins to pick up electrical vibrations from the electrodes connected to the person.

Typically, such a signal is 10 mm in height and 1 millivolt (mV). This is the same calibration, control point.

All measurements of the teeth are made in the second lead. On the tape it is indicated by the Roman numeral II. The R wave should correspond to the control point, and based on it, the norm of the remaining teeth is calculated:

• height T 1/2 (0.5 mV)
• depth S - 1/3 (0.3 mV)
• height P - 1/3 (0.3 mV)
• depth Q - 1/4 (0.2 mV)

The distance between the teeth and intervals is calculated in seconds. Ideally, they look at the width of the P wave, which is equal to 0.10 seconds, and the subsequent length of the waves and intervals is equal to 0.02 seconds each time.

Thus, the width of the P wave is 0.10±0.02 sec. During this time, the impulse will cover both atria with excitement; P - Q: 0.10±0.02 sec; QRS: 0.10±0.02 sec; to complete a full circle (excitation passing from the sinus node through the atrioventricular connection to the atria, ventricles) in 0.30±0.02 sec.

Let's look at several normal ECGs for different ages (in a child, in adult men and women)

It is very important to take into account the patient’s age, his general complaints and condition, as well as current health problems, since even the slightest cold can affect the results.

Moreover, if a person plays sports, then his heart “gets used” to working in a different mode, which is reflected in the final results. An experienced doctor always takes into account all relevant factors.

Normal ECG for a teenager (11 years old). For an adult this will not be the norm.

Normal ECG of a young person (age 20 - 30 years).

ECG analysis is evaluated according to the direction of the electrical axis, in which the Q-R-S interval is of greatest importance. Any cardiologist also looks at the distance between the teeth and their height.

The inventory of the resulting diagram is made according to a specific template:

• An assessment of the heart rhythm is carried out with the measurement of heart rate (heart rate) at a normal rate: sinus rhythm, heart rate - 60 - 90 beats per minute.
• Calculation of intervals: Q-T at a rate of 390 - 440 ms.

This is necessary to estimate the duration of the contraction phase (they are called systoles). In this case, they resort to the Bazett formula. An extended interval indicates coronary heart disease, atherosclerosis, myocarditis, etc. A short interval may be associated with hypercalcemia.

• Cardiac electrical axis (ECA) assessment

This parameter is calculated from the isoline taking into account the height of the teeth. With a normal heart rhythm, the R wave should always be higher than S. If the axis deviates to the right, and S is higher than R, then this indicates disorders in the right ventricle, with a deviation to the left in leads II and III - left ventricular hypertrophy.

• Evaluation of the Q - R - S complex

Normally, the interval should not exceed 120 ms. If the interval is distorted, then this may indicate various blockades in the conduction pathways (branch branches in the His bundles) or conduction disturbances in other areas. These indicators can detect hypertrophy of the left or right ventricles.

• an inventory of the S - T segment is maintained

It can be used to judge the readiness of the heart muscle to contract after its complete depolarization. This segment should be longer than the Q-R-S complex.

What do Roman numerals mean on an ECG?

Each point to which the electrodes are connected has its own meaning. It records electrical vibrations and the recorder reflects them on the tape. To correctly read the data, it is important to correctly install the electrodes on a certain area.

For example:

• the potential difference between two points of the right and left hand is recorded in the first lead and is designated I
• the second lead is responsible for the potential difference between the right arm and left leg - II
• third between left arm and left leg - III

If we mentally connect all these points, we get a triangle named after the founder of electrocardiography, Einthoven.

In order not to confuse them with each other, all electrodes have wires of different colors: red is attached to the left hand, yellow to the right, green to the left leg, black to the right leg, it acts as a grounding connection.

This arrangement refers to a bipolar lead. It is the most common, but there are also single-pole circuits.

Such a single-pole electrode is designated by the letter V. The recording electrode installed on the right hand is designated by the sign VR, on the left, respectively, by VL. On the leg - VF (food - leg). The signal from these points is weaker, so it is usually amplified; the tape is marked “a”.

The chest leads are also slightly different. The electrodes are attached directly to the chest. Receiving impulses from these points are the strongest and clearest. They do not require amplification. Here the electrodes are located strictly according to the agreed standard:

designation	electrode attachment location
V1	in the 4th intercostal space at the right edge of the sternum
V2	in the 4th intercostal space at the left edge of the sternum
V3	halfway between V2 and V4
V4
V5	in the 5th intercostal space at the midclavicular line
V6	at the intersection of the horizontal level of the 5th intercostal space and the midaxillary line
V7	at the intersection of the horizontal level of the 5th intercostal space and the posterior axillary line
V8	at the intersection of the horizontal level of the 5th intercostal space and the midscapular line
V9	at the intersection of the horizontal level of the 5th intercostal space and the paravertebral line

A standard study uses 12 leads.

How to determine pathologies in the heart

When answering this question, the doctor pays attention to the person’s diagram and, based on the basic symbols, can guess which particular department has begun to malfunction.

We will display all the information in table form.

designation	myocardium department
I	anterior wall of the heart
II	summary display I and III
III	posterior wall of the heart
aVR	right lateral wall of the heart
aVL	left anterolateral wall of the heart
aVF	posterior inferior wall of the heart
V1 and V2	right ventricle
V3	interventricular septum
V4	apex of the heart
V5	anterolateral wall of the left ventricle
V6	lateral wall of the left ventricle

Taking into account all of the above, you can learn how to decipher a tape using at least the simplest parameters. Although many serious abnormalities in the functioning of the heart will be visible to the naked eye even with this set of knowledge.

For clarity, we will describe several of the most disappointing diagnoses so that you can simply visually compare the norm and deviations from it.

Myocardial infarction

Judging by this ECG, the diagnosis will be disappointing. The only positive thing here is the duration of the Q-R-S interval, which is normal.

In leads V2 - V6 we see ST elevation.

This is the result acute transmural ischemia(AMI) of the anterior wall of the left ventricle. Q waves are visible in the anterior leads.

On this tape we see a conduction disturbance. However, even with this fact it is noted acute anteroseptal myocardial infarction against the background of right bundle branch block.

The right chest leads dismantle the S-T elevation and positive T waves.

Rhythm - sinus. There are high, regular R waves, and pathology of the Q waves in the posterolateral regions.

Deviation visible ST in I, aVL, V6. All this indicates posterolateral myocardial infarction with coronary heart disease (CHD).

Thus, the signs of myorcardial infarction on the ECG are:

• tall T wave
• elevation or depression of the S-T segment
• pathological Q wave or its absence

Signs of myocardial hypertrophy

Zheludochkov

For the most part, hypertrophy is characteristic of those people whose heart has for a long time experienced additional stress as a result of, say, obesity, pregnancy, or some other disease that negatively affects the non-vascular activity of the entire body as a whole or individual organs (in particular the lungs, kidneys).

Hypertrophied myocardium is characterized by several signs, one of which is an increase in the time of internal deviation.

What does it mean?

Excitement will have to spend more time passing through the cardiac sections.

The same applies to the vector, which is also larger and longer.

If you look for these signs on the tape, the R wave will be higher in amplitude than normal.

A characteristic symptom is ischemia, which is a consequence of insufficient blood supply.

Blood flows through the coronary arteries to the heart, which, as the thickness of the myocardium increases, encounters an obstacle on the way and slows down. Impaired blood supply causes ischemia of the subendocardial layers of the heart.

Based on this, the natural, normal function of the pathways is disrupted. Inadequate conduction leads to disruptions in the process of ventricular excitation.

After which a chain reaction is started, because the work of other departments depends on the work of one department. If there is hypertrophy of one of the ventricles, then its mass increases due to the growth of cardiomyocytes - these are cells that participate in the process of transmitting nerve impulses. Therefore, its vector will be greater than the vector of a healthy ventricle. On the electrocardiogram tape it will be noticeable that the vector will be deviated towards the localization of hypertrophy with a displacement of the electrical axis of the heart.

The main signs also include changes in the third chest lead (V3), which is something like a transshipment, transition zone.

What kind of zone is this?

It includes the height of the R wave and the depth of S, which are equal in absolute value. But when the electrical axis changes as a result of hypertrophy, their ratio will change.

Let's look at specific examples

In sinus rhythm, left ventricular hypertrophy is clearly visible with characteristic tall T waves in the precordial leads.

There is nonspecific ST depression in the inferolateral region.

The EOS (electrical axis of the heart) is deviated to the left with anterior hemiblock and prolongation of the QT interval.

High T waves indicate that in addition to hypertrophy, a person also has hyperkalemia most likely developed against the background of renal failure and, which are characteristic of many patients who have been ill for many years.

In addition, a longer QT interval with ST depression indicates hypocalcemia, which progresses in the later stages (with chronic renal failure).

This ECG corresponds to an elderly person who has serious kidney problems. He is on the verge.

Atrial

As you already know, the total value of atrial excitation on the cardiogram is shown by the P wave. In case of failures in this system, the width and/or height of the peak increases.

With right atrial hypertrophy (RAH), P will be higher than normal, but not wider, since the peak excitation of the RA ends before the excitation of the left. In some cases, the peak takes on a pointed shape.

With HLP, an increase in the width (more than 0.12 seconds) and height of the peak is observed (double hump appears).

These signs indicate a disturbance in impulse conduction, which is called intraatrial block.

Blockades

Blockades refer to any disruptions in the conduction system of the heart.

A little earlier, we looked at the path of the impulse from the sinus node through the pathways to the atria; at the same time, the sinus impulse rushes along the lower branch of Bachmann’s bundle and reaches the atrioventricular connection, passing through it it undergoes a natural delay. After which it enters the ventricular conduction system, presented in the form of bundles of His.

Depending on the level at which the failure occurred, the violation is distinguished:

• intraatrial conduction (blockade of sinus impulse in the atria)
• atrioventricular
• intraventricular

Intraventricular conduction

This system is presented in the form of a trunk of His, divided into two branches - the left and right legs.

The right leg “supplies” the right ventricle, within which it branches into many small networks. Appears in the form of one wide bundle with branches inside the ventricular muscles.

The left leg is divided into anterior and posterior branches, which “adjoin” the anterior and posterior walls of the left ventricle. Both of these branches form a network of smaller branches within the LV musculature. They are called Purkinje fibers.

Right bundle branch block

The course of the impulse first covers the path through the excitation of the interventricular septum, and then the unblocked LV is first involved in the process, through its normal course, and only then the right one is excited, to which the impulse reaches along a distorted path through the Purkinje fibers.

Of course, all this will affect the structure and shape of the QRS complex in the right chest leads V1 and V2. At the same time, on the ECG we will see bifurcated vertices of the complex, similar to the letter “M”, in which R is the excitation of the interventricular septum, and the second R1 is the actual excitation of the RV. S will continue to be responsible for LV excitation.

On this tape we see incomplete blockade of PNPG and AB blockade of the first degree, there are also r traumatic changes in the posterior diaphragmatic region.

Thus, the signs of right bundle branch block are as follows:

• prolongation of the QRS complex in standard lead II by more than 0.12 sec.
• increase in the time of internal deviation of the RV (in the graph above this parameter is presented as J, which is more than 0.02 seconds in the right chest leads V1, V2)
• deformation and splitting of the complex into two “humps”
• negative T wave

Left bundle branch block

The course of excitation is similar, the impulse reaches the LV through a roundabout pathway (it does not pass through the left bundle branch, but through the network of Purkinje fibers from the RV).

Characteristic features of this phenomenon on the ECG:

• widening of the ventricular QRS complex (more than 0.12 sec)
• increase in internal deviation time in a blocked LV (J greater than 0.05 sec)
• deformation and bifurcation of the complex in leads V5, V6
• negative T wave (-TV5, -TV6)

Block (incomplete) of the left bundle branch

It is also worth paying attention to the fact that the S wave will be “atrophied”, i.e. it will not be able to reach the isoline.

Atrioventricular block

There are several degrees:

• I - conduction slowing is characteristic (heart rate is normally in the range of 60 - 90; all P waves are associated with the QRS complex; the P-Q interval is more than normal 0.12 sec.)
• II - incomplete, divided into three options: Mobitz 1 (heart rate slows down; not all P waves are associated with the QRS complex; the P - Q interval changes; periodicity 4:3, 5:4, etc. appears), Mobitz 2 (also the same, but the P - Q interval is constant; periodicity 2:1, 3:1), high-grade (heart rate significantly reduced; periodicity: 4:1, 5:1; 6:1)
• III - complete, divided into two options: proximal and distal

We’ll go into detail, but we’ll just point out the most important things:

• The transit time along the atrioventricular junction is normally 0.10±0.02. Total, no more than 0.12 seconds.
• reflected on the interval P - Q
• This is where physiological impulse delay occurs, which is important for normal hemodynamics

AV block II degree Mobitz II

Such disturbances lead to failures of intraventricular conduction. Typically, people with this type of tape experience shortness of breath, dizziness, or become overtired easily. In general, this is not so scary and occurs very often even among relatively healthy people who do not particularly complain about their health.

Rhythm disturbance

Signs of arrhythmia are usually visible to the naked eye.

When excitability is disrupted, the time of the myocardial response to an impulse changes, which creates characteristic graphs on the tape. Moreover, it is worth understanding that not in all parts of the heart the rhythm can be constant, taking into account the fact that there is, say, some kind of blockade that inhibits the transmission of impulses and distorts the signals.

So, for example, the following cardiogram indicates atrial tachycardia, and the one below it indicates ventricular tachycardia with a frequency of 170 beats per minute (LV).

Correct is sinus rhythm with a characteristic sequence and frequency. Its characteristics are as follows:

• frequency of P waves in the range of 60-90 per minute
• R-R interval is the same

• the P wave is positive in standard lead II
• the P wave is negative in lead aVR

Any arrhythmia indicates that the heart works in a different mode, which cannot be called regular, familiar and optimal. The most important thing in determining the correctness of the rhythm is the uniformity of the P-P wave interval. Sinus rhythm is correct when this condition is met.

If there is a slight difference in the intervals (even 0.04 seconds, not exceeding 0.12 seconds), then the doctor will already indicate a deviation.

The rhythm is sinus, incorrect, since the P-P intervals differ by no more than 0.12 seconds.

If the intervals are more than 0.12 seconds, this indicates an arrhythmia. These include:

• extrasystole (most common)
• paroxysmal tachycardia
• flicker
• fluttering, etc.

Arrhythmia has its own focus of localization when a rhythm disturbance occurs on the cardiogram in certain parts of the heart (in the atria, ventricles).

The most striking sign of atrial flutter is high-frequency impulses (250 - 370 beats per minute). They are so strong that they overlap the frequency of sinus impulses. There will be no P waves on the ECG. In their place, sharp, sawtooth, low-amplitude “teeth” (no more than 0.2 mV) will be visible on lead aVF.

Holter ECG

This method is otherwise abbreviated as HM ECG.

What it is?

Its advantage is that it is possible to carry out daily monitoring of the work of the heart muscle. The reading device (recorder) itself is compact. It is used as a portable device capable of recording signals transmitted through electrodes onto magnetic tape for a long period of time.

On a conventional stationary device, it turns out to be quite difficult to notice some periodically occurring surges and disruptions in the functioning of the myocardium (given the asymptomatic nature), and to ensure the correctness of the diagnosis, the Holter method is used.

The patient is asked to independently, after medical instructions, keep a detailed diary, since some pathologies can manifest themselves at a certain time (the heart “prickles” only in the evenings and not always; in the mornings something “presses” on the heart).

While observing, a person writes down everything that happens to him, for example: when he was at rest (sleeping), overtired, running, speeding up, working physically or mentally, nervous, worried. At the same time, it is also important to listen to yourself and try to describe as clearly as possible all your feelings and symptoms that accompany certain actions and events.

Data collection time usually lasts no longer than a day. During such daily monitoring, the ECG allows you to get a clearer picture and determine the diagnosis. But sometimes the data collection time can be extended to several days. It all depends on the person’s well-being and the quality and completeness of previous laboratory tests.

Typically, the basis for prescribing this type of analysis is painless symptoms of coronary heart disease, latent hypertension, when doctors have suspicions or doubts about any diagnostic data. In addition, it may be prescribed when prescribing new medications for the patient that affect the functioning of the myocardium, which are used in the treatment of ischemia, or if there is an artificial pacemaker, etc. This is also done for the purpose of assessing the patient’s condition in order to assess the degree of effectiveness of the prescribed therapy, etc.

How to prepare for HM ECG

Usually there is nothing difficult in this process. However, it is worth understanding that the device can be influenced by other devices, especially those emitting electromagnetic waves.

Interaction with any metal is also not advisable (rings, earrings, metal buckles, etc. should be removed). The device must be protected from moisture (full body hygiene in the shower or taking a bath is unacceptable).

Synthetic fabrics also negatively affect the results, as they can create static voltage (they become electrified). Any such “splash” from clothing, bedspreads, etc. distorts the data. Replace them with natural ones: cotton, linen.

The device is extremely vulnerable and sensitive to magnets, do not stand near a microwave oven or induction hob, and avoid being near high-voltage wires (even if you drive in a car through a small section of the road over which high-voltage lines lie).

How is data collected?

Usually the patient is given a referral, and at the appointed time he comes to the hospital, where the doctor, after some theoretical introductory course, installs electrodes on certain areas of the body, which are connected by wires to a compact recorder.

The recorder itself is a small device that records any electromagnetic vibrations and remembers them. It is attached to the belt and hidden under clothes.

Men sometimes have to shave in advance some areas of the body where electrodes are attached (for example, “free” the chest of hair).

After all the preparations and installation of equipment, the patient can go about his usual activities. He should integrate into his daily life as if nothing had happened, however, without forgetting to take notes (it is extremely important to indicate the time of manifestation of certain symptoms and events).

After the period specified by the doctor, the “subject” returns to the hospital. The electrodes are removed from it and the reading device is taken away.

Using a special program, the cardiologist will process data from the recorder, which, as a rule, is easily synchronized with a PC and will be able to make a specific inventory of all the results obtained.

A method of functional diagnostics such as an ECG is much more effective, since thanks to it you can notice even the slightest pathological changes in the work of the heart, and it is widely used in medical practice to identify life-threatening diseases such as a heart attack.

For diabetics with late cardiovascular complications that have developed against the background of diabetes mellitus, it is especially important to periodically undergo it at least once a year.

If you find an error, please select a piece of text and press Ctrl+Enter.

To determine the diagnosis, one of the most indispensable aids to a doctor is a cardiogram. It can help identify important heart diseases such as myocardial infarction or arrhythmia. And at the same time, it is inexpensive and accessible to everyone, and the method of its construction is based on a careful study of the bioelectrical activity of the heart muscles. Now we will teach anyone to read a cardiogram.

1. When recording an ECG, it is important to avoid all kinds of interference and guidance currents; the minivolt should not exceed ten millimeters
2. Heart rhythm is determined by the frequency of heart contractions and their regularity, conductivity and the source of excitation are determined. This is determined by comparing the duration of the R-R intervals. If the heart rate rhythm is correct, this is calculated by dividing 60 by the second-by-second interval R-R.

3. The algebraic axis of the heart is calculated by determining the sum of the amplitudes of the QRS waves at any limb lead points.
4. Carefully examine the atrial scar R. Measure its amplitude along the isoline from the top of the wave; it should be no more than twenty-five millimeters. Measure the distance from start to finish; if the person is healthy, it will not exceed 0.1 second.
5. The PQ interval is an indicator of the speed of impulse delivery from the atrium to the ventricles. Its interval should be between 0.12 and 0.1 seconds. You also need to analyze the ventricular QRS complex, measuring the amplitude of the complex and the duration of each of its teeth.

6. Analyze the T wave. It reflects the relaxation phase of the heart muscle. It is necessary to determine its polarity, amplitude and shape. When a person is healthy, this wave is positive and has the same polarity as the wave responsible for the ventricular complex. Its shape should be gently ascending and have a steeply descending bend.