Deciphering a cardiogram in children and adults: general principles, reading the results, an example of decoding. Deciphering the ECG, how to independently decipher the cardiogram of the heart in adults Electrocardiography of the heart

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

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

Deciphering the ECG is within the power of every even a child, given the fact that the patient understands the basic canons of the heart. Those same teeth on the tape are the peak (response) of the heart to contraction. The more often they are, the faster the myocardial contraction occurs, the smaller they are, the slower the heartbeat occurs, and in fact the transmission of the 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, also have late cardiovascular complications, allows us to assess the severity of the disease and intervene in time 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 in a pregnant woman will be somewhat different, since in the process of fetal growth, a natural displacement of the internal organs occurs, which are displaced by the expanding uterus. Their heart occupies a different position in the chest area, therefore, there is a shift in the electrical axis.

In addition, the longer the period, the greater the load experienced by the heart, 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, according to the results, reported the same tachycardia, since it is she who can most often 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 correctly pass the analysis, it is necessary to understand that any excitement, excitement and experience will inevitably affect the results. Therefore, it is important to prepare yourself in advance.

Invalid

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

It is not uncommon for a patient, being late to the treatment room at the appointed time, to become very worried or frantically rush to the cherished office, forgetting about everything in the world. As a result, his leaf was mottled with frequent sharp teeth, and the doctor, of course, recommended that his patient re-examine. 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 behind the screen to the waist (women take off their bra) and lie down on the couch. In some treatment rooms, depending on the alleged diagnosis, it is also required to free the body from below the torso to the underwear.

After that, the nurse applies a special gel to the abduction sites, to which he attaches electrodes, 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 captured, which is recorded by means of 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 transferred directly to a cardiologist who deciphers. With notes and transcripts, the tape is sent to the attending physician or transferred to the registry 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 slightly open the veil of secrecy so that you can at least a little bit appreciate 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, on the other hand, reflects the transmission of an impulse that passes through all parts of the heart over a certain period of time.

To understand these scribbles, it is necessary 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 conditionally displays marks in the form of Latin letters: P, Q, R, S, T

Let's see 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 the change in the form of a peak of excitation of the right atrium. After the conduction system - the interatrial bundle of Bachmann passes into the left atrium. Its activity occurs at the moment when the right atrium is already fully covered by excitation.

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

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

Interval P - Q

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

This is where the natural delay occurs. Therefore, a straight line appears on the tape, which is called isoelectric.

In evaluating the interval, the time it takes for the impulse to pass through this connection and subsequent departments plays a role.

The count is in seconds.

Complex Q, R, S

After the impulse, passing along the conducting paths in the form of a bundle of His and Purkinje fibers, reaches the ventricles. This whole process is presented on the tape as 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 septum between the ventricles is covered by excitation. This takes about 0.03 sec. A Q wave appears on the chart, extending just below the main line.

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

After that, 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, the QRS is an entire ventricular complex with a total duration of 0.10 seconds.

S-T interval

Since myocardial cells cannot be in excitation for a long time, there comes a moment of decline when the impulse fades. By this time, the process of restoring the original state that prevailed before the excitement starts.

This process is also recorded on the ECG.

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

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

ECG norm

These are the main designations, looking at which one can judge the speed and intensity of the beating of the heart muscle. But in order to get a more complete picture, it is necessary to reduce all the data to some single standard of the ECG norm. 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 equal in height to 10 mm 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 must correspond to the control point, and based on it, the rate 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 teeth and intervals is calculated in seconds. Ideally, look at the width of the P wave, which is equal to 0.10 sec, and the subsequent length of the teeth and intervals is equal to 0.02 sec 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 excitation; P - Q: 0.10±0.02 sec; QRS: 0.10±0.02 sec; for passing 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 a few normal ECGs for different ages (in a child, in adult men and women)

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

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

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

The norm of the ECG of a young man (age 20 - 30 years).

The description of the resulting diagram is made according to a certain template:

• An assessment of the heart rate is carried out with the measurement of heart rate (heart rate) at the norm: the rhythm is sinus, the heart rate is 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, Bazett's formula is used. An extended interval indicates coronary heart disease, atherosclerosis, myocarditis, etc. A short interval may be associated with hypercalcemia.

• Assessment of the electrical axis of the heart (EOS)

This parameter is calculated from the isoline, taking into account the height of the teeth. In 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.

• Q-R-S Complex Assessment

Normally, the interval should not exceed 120 ms. If the interval is distorted, then this may indicate various blockades in the conductive pathways (peduncles in the bundles of His) or conduction disturbances in other areas. According to these indicators, hypertrophy of the left or right ventricles can be detected.

• an inventory of the S-T segment is being conducted

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 on an ECG mean?

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

For example:

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

If we mentally connect all these points, then 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 ground.

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 indicated by the letter V. The recording electrode, mounted on the right hand, is indicated by the sign VR, on the left, respectively, VL. On the leg - VF (food - leg). The signal from these points is weaker, so it is usually amplified, there is an “a” mark on the tape.

The chest leads are also slightly different. The electrodes are attached directly to the chest. Receiving impulses from these points is the strongest, clearest. They don't require amplification. Here the electrodes are arranged strictly according to the agreed standard:

The standard study uses 12 leads.

How to identify pathologies in the work of the heart

When answering this question, the doctor pays attention to the diagram of a person and, according to the main designations, he can guess which particular department began to fail.

We will display all the information in the form of a table.

Considering all of the above, you can learn how to decipher the tape at least according to the simplest parameters. Although many serious deviations in the work of the heart will be visible to the naked eye, even with this set of knowledge.

For clarity, we will describe some 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. Here, from the positive, only 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 seen in the anterior leads.

On this tape, we see a conduction disturbance. However, even with this fact, acute anterior-septal myocardial infarction against the background of blockade of the right leg of the bundle of His.

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

Rimm - sinus. Here, there are high regular R waves, the pathology of the Q waves in the posterolateral sections.

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

Thus, the signs of myocardial 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

Ventricular

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

The hypertrophied myocardium is characterized by several signs, one of which is an increase in the time of internal deflection.

What does it mean?

Excitation will have to spend more time passing through the cardiac departments.

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

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

A characteristic symptom is ischemia, which is the result of insufficient blood supply.

Through the coronary arteries to the heart there is a blood flow, which, with an increase in the thickness of the myocardium, encounters an obstacle on the way and slows down. Violation of the 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 failures in the process of excitation of the ventricles.

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

The main features include a change 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 tooth and the depth S, which are equal in their absolute value. But when the electrical axis changes as a result of hypertrophy, their ratio will change.

Consider specific examples

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

There is nonspecific ST depression in the inferolateral region.

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

High T waves indicate that a person has, in addition to hypertrophy, also 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 that progresses in advanced stages (chronic renal failure).

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

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 (RAA), P will be higher than normal, but not wider, since the peak of the excitation of the PP ends before the excitation of the left. In some cases, the peak takes on a pointed shape.

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

These signs indicate a violation of the conduction of the impulse, which is called intra-atrial blockade.

blockades

Blockades are understood as any failures in the conduction system of the heart.

A little earlier, we looked at the path of the impulse from the sinus node through the conducting paths to the atria, at the same time, the sinus impulse rushes along the lower branch of the Bachmann bundle and reaches the atrioventricular junction, passing through it, it undergoes a natural delay. Then it enters the conduction system of the ventricles, presented in the form of His bundles.

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

• intra-atrial conduction (sinus impulse block 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, inside which it branches into many small networks. It appears as one wide bundle with branches inside the muscles of the ventricle.

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

Blockade of the right leg of the bundle of His

The course of the impulse first covers the path through the excitation of the interventricular septum, and then the first unblocked LV is involved in the process, through its normal course, and only after that the right one is excited, to which the impulse reaches the 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 peaks 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 pancreas. S, as before, will be responsible for the excitation of the left ventricle.

On this tape we see incomplete RBBB and 1st degree AB block, there are also p ubtsovye changes in the posterior diaphragmatic region.

Thus, the signs of blockade of the right leg of the bundle of His are as follows:

• elongation of the QRS complex in standard lead II for more than 0.12 sec.
• an increase in the time of internal deflection of the right ventricle (on the graph above, this parameter is presented as J, which is more than 0.02 sec in the right chest leads V1, V2)
• deformation and splitting of the complex into two "humps"
• negative T wave

Blockade of the left leg of the bundle of His

The course of excitation is similar, the impulse reaches the LV through detours (it does not pass along the left leg of the His bundle, but through the network of Purkinje fibers from the pancreas).

Characteristic features of this phenomenon on the ECG:

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

Blockade (incomplete) of the left leg of the bundle of His

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

Atrioventricular block

There are several degrees:

• I - slow conduction is characteristic (heart rate is normal within 60 - 90; all P waves are associated with the QRS complex; 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; periodicals appear 4:3, 5:4, etc.), Mobitz 2 (also most, but the interval P - Q is constant; periodicity 2:1, 3:1), high-grade (significantly reduced heart rate; periodicity: 4:1, 5:1; 6:1)
• III - complete, divided into two options: proximal and distal

Well, we will go into details, but only note the most important:

• the time of passage through the atrioventricular junction is normally 0.10±0.02. Total, no more than 0.12 sec.
• reflected on the interval P - Q
• here there is a physiological impulse delay, which is important for normal hemodynamics

AV block II degree Mobitz II

Such violations lead to failures of intraventricular conduction. Usually people with such a tape have shortness of breath, dizziness, or they quickly overwork. In general, this is not so scary and is very common 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 disturbed, the response time of the myocardium to the impulse changes, which creates characteristic graphs on the tape. Moreover, it should be understood that not in all cardiac departments 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 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).

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

• frequency of P waves in the range of 60-90 per minute
• RR spacing is the same

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

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

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

The rhythm is sinus, irregular, since the RR intervals differ by no more than 0.12 sec.

If the intervals are more than 0.12 seconds, then this indicates an arrhythmia. It includes:

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

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

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.

ECG Holter

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 reader itself (recorder) is compact. It is used as a portable device capable of recording signals from electrodes on a magnetic tape for a long period of time.

On a conventional stationary device, it is quite difficult to notice some intermittent jumps and malfunctions in the work of the myocardium (given the asymptomaticity) and the Holter method is used to make sure the diagnosis is correct.

The patient is invited to keep a detailed diary on his own after medical instructions, since some pathologies can manifest themselves at a certain time (the heart “collapses” only in the evenings and then 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 (sleep), overworked, ran, quickened his pace, worked physically or mentally, was 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, symptoms that accompany certain actions, events.

The time of data collection usually lasts no longer than a day. For such daily monitoring of 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.

Usually, the basis for prescribing this type of analysis is the painless symptoms of coronary heart disease, latent hypertension, when doctors have suspicions, doubts about any diagnostic data. In addition, they can prescribe it when prescribing new drugs 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 in order to assess the patient's condition in order to assess the degree of effectiveness of the prescribed therapy, and so on.

How to prepare for HM ECG

Usually there is nothing complicated in this process. However, it should be understood that other devices, especially emitting electromagnetic waves, can affect the device.

Interaction with any metal is also not desirable (rings, earrings, metal buckles, etc. should be removed). The device must be protected from moisture (complete body hygiene under the shower or bath is unacceptable).

Synthetic fabrics also negatively affect the results, as they can create static voltage (they become electrified). Any such “splash” from clothes, bedspreads and other things 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 an induction hob, avoid being near high-voltage wires (even if you drive 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 parts of the body, which are connected by wires to a compact recorder.

The registrar itself is a small device that captures any electromagnetic vibrations and remembers them. It fastens on the belt and hides under the clothes.

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

After all preparations and installation of equipment, the patient can go about his usual activities. He should merge into his daily life as if nothing had happened, though not forgetting to take notes (it is extremely important to indicate the time of manifestation of certain symptoms and events).

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

The cardiologist, using a special program, will process the 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.

Such a method of functional diagnostics as an ECG is much more effective, since thanks to it even the slightest pathological changes in the work of the heart can be noticed, and it is widely used in medical practice in order to identify life-threatening diseases in patients like a heart attack.

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

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

Complete blockade of the right leg of the bundle of His (RBBNPG). A 62-year-old patient with complaints of cough, a clinical picture of acute bronchitis. No acute coronary pathology was detected.

Atrial extrasystole. A 73-year-old patient applied for a worsening course of hypertension. Interruptions in the work of the heart does not feel, urgent treatment is not required.

atrial flutter

Atrial flutter, correct form 2:1, heart rate 130 per minute. A 66-year-old patient has been worried about palpitations for 1 month. Previously, rhythm disturbances were not detected.

Atrial flutter, irregular shape, heart rate 104 per minute. The same patient after intravenous administration of 10 mg of verapamil.

Paroxysmal supraventricular tachycardia

Paroxysmal supraventricular tachycardia. A 66-year-old patient complains of general weakness, palpitations for 1 hour. She has a history of repeated PSVT paroxysms. The paroxysm was stopped by intravenous bolus administration of ATP 10 mg.

Sinus bradycardia

sinus bradycardia. Heart rate 42 per minute. A 54-year-old patient complains of general weakness, dizziness, nausea, and vomiting. AD 60/30. Toxic effect of ethanol. After intravenous administration of 0.5 ml of atropine, an increase in heart rate to 64 per minute.

Atrial fibrillation

Atrial fibrillation, normosystole, heart rate 82 per minute. A 83-year-old female patient presented with chest pain of vertebrogenic origin. In the anamnesis - ischemic heart disease. Permanent form of atrial fibrillation. There are no dynamics with the previous ECG. Rhythm and heart rate correction is not required.

Acute myocardial infarction

Acute anterolateral myocardial infarction. The patient is 72 years old, the duration of the pain attack is 8 hours. A typical attack of anginal pain, accompanied by sweating, weakness. Nitrates without effect. Treatment according to the ACS standard with ST-segment elevation, the pain syndrome was stopped after the administration of morphine. She was admitted to the vascular center for coronary angiography and further treatment.

Electrocardiography (ECG)- one of the electrophysiological methods for recording biopotentials of the heart. Electrical impulses from the heart tissue are transmitted to skin electrodes located on the arms, legs and chest. This data is then output either graphically on paper or displayed on a display.

In the classic version, depending on the location of the electrode, the so-called standard, reinforced and chest leads are distinguished. Each of them shows bioelectric impulses taken from the heart muscle at a certain angle. Thanks to this approach, as a result, a complete characteristic of the work of each section of the heart tissue emerges on the electrocardiogram.

Figure 1. ECG tape with graphic data

What does the ECG of the heart show? Using this common diagnostic method, you can determine the specific place in which the pathological process occurs. In addition to any disturbances in the work of the myocardium (heart muscle), the ECG shows the spatial location of the heart in the chest.

Main tasks of electrocardiography

1. Timely determination of violations of rhythm and heart rate (detection of arrhythmias and extrasystoles).
2. Determination of acute (myocardial infarction) or chronic (ischemia) organic changes in the heart muscle.
3. Identification of violations of intracardiac conduction of nerve impulses (violation of the conduction of an electrical impulse along the conduction system of the heart (blockade)).
4. Definition of some acute (PE - pulmonary embolism) and chronic (chronic bronchitis with respiratory failure) pulmonary diseases.
5. Identification of electrolyte (potassium, calcium levels) and other changes in the myocardium (dystrophy, hypertrophy (increase in the thickness of the heart muscle)).
6. Indirect registration of inflammatory heart diseases (myocarditis).

Disadvantages of the method

The main disadvantage of electrocardiography is the short-term registration of indicators. Those. the recording shows the work of the heart only at the time of taking the ECG at rest. Due to the fact that the above disorders can be transient (appear and disappear at any time), specialists often resort to daily monitoring and recording of ECG with exercise (stress tests).

Indications for an ECG

Electrocardiography is performed on a planned or emergency basis. Scheduled ECG registration is carried out during pregnancy, when a patient is admitted to a hospital, in the process of preparing a person for operations or complex medical procedures, to assess cardiac activity after certain treatment or surgical medical interventions.

With the preventive purpose of the ECG is prescribed:

• people with high blood pressure;
• with vascular atherosclerosis;
• in case of obesity;
• with hypercholesterolemia (increased blood cholesterol levels);
• after some transferred infectious diseases (tonsillitis, etc.);
• with diseases of the endocrine and nervous systems;
• persons over 40 years old and people prone to stress;
• with rheumatological diseases;
• people with occupational risks and hazards to assess professional suitability (pilots, sailors, athletes, drivers…).

On an emergency basis, i.e. "This very minute" ECG is assigned:

• with pain or discomfort behind the sternum or in the chest;
• in case of severe shortness of breath;
• with prolonged severe pain in the abdomen (especially in the upper sections);
• in case of persistent increase in blood pressure;
• in case of unexplained weakness;
• with loss of consciousness;
• with a chest injury (in order to exclude damage to the heart);
• at the time of or after a heart rhythm disorder;
• with pain in the thoracic spine and back (especially on the left);
• with severe pain in the neck and lower jaw.

Contraindications for ECG

There are no absolute contraindications to ECG removal. Relative contraindications to electrocardiography may be various violations of the integrity of the skin in the places where the electrodes are attached. However, it should be remembered that in the case of emergency indications, the ECG should always be taken without exception.

Preparation for electrocardiography

There is also no special preparation for an ECG, but there are some nuances of the procedure that the doctor should warn the patient about.

1. It is necessary to know if the patient is taking heart medications (should be noted on the referral form).
2. During the procedure, you can not talk and move, you must lie down, relaxed and breathe calmly.
3. Listen and follow the simple commands of the medical staff, if necessary (inhale and hold for a few seconds).
4. It is important to know that the procedure is painless and safe.

Distortion of the electrocardiogram record is possible when the patient moves or if the device is not properly grounded. The reason for incorrect recording can also be a loose fit of the electrodes to the skin or their incorrect connection. Interference in the recording often occurs with muscle tremors or electrical pickup.

Conducting an electrocardiogram or how an ECG is done

• to the right hand - a red electrode;
• to the left hand - yellow;
• to the left leg - green;
• to the right leg - black.

Then 6 more electrodes are applied to the chest.

After the patient is fully connected to the ECG device, a recording procedure is performed, which on modern electrocardiographs lasts no more than one minute. In some cases, the health worker asks the patient to inhale and not breathe for 10-15 seconds and conducts an additional recording during this time.

At the end of the procedure, the ECG tape indicates the age, full name. patient and the speed at which the cardiogram was taken. Then a specialist decrypts the recording.

ECG decoding and interpretation

The interpretation of the electrocardiogram is carried out either by a cardiologist, or a doctor of functional diagnostics, or a paramedic (in an ambulance). The data is compared with a reference ECG. On the cardiogram, five main teeth (P, Q, R, S, T) and an inconspicuous U-wave are usually distinguished.

Table 1. ECG interpretation in adults is normal

Various changes in the teeth (their width) and intervals may indicate a slowdown in the conduction of a nerve impulse through the heart. T-wave inversion and/or ST interval rise or fall relative to the isometric line indicates possible damage to myocardial cells.

During the decoding of the ECG, in addition to studying the shapes and intervals of all teeth, a comprehensive assessment of the entire electrocardiogram is carried out. In this case, the amplitude and direction of all teeth in standard and enhanced leads are studied. These include I, II, III, avR, avL and avF. (see Fig. 1) Having a summary picture of these ECG elements, one can judge the EOS (electrical axis of the heart), which shows the presence of blockades and helps determine the location of the heart in the chest.

For example, in obese individuals, the EOS may be deviated to the left and down. Thus, the decoding of the ECG contains all the information about the source of the heart rate, conduction, the size of the heart chambers (atria and ventricles), myocardial changes and electrolyte disturbances in the heart muscle.

The main and most important clinical significance of the ECG is in myocardial infarction, cardiac conduction disorders. Analyzing the electrocardiogram, you can get information about the focus of necrosis (localization of myocardial infarction) and its duration. It should be remembered that ECG assessment should be carried out in combination with echocardiography, daily (Holter) ECG monitoring and functional stress tests. In some cases, the ECG can be practically uninformative. This is observed with massive intraventricular blockade. For example, PBLNPG (complete blockade of the left leg of the Hiss bundle). In this case, it is necessary to resort to other diagnostic methods.

Video on the topic "ECG norm"

Deciphering the ECG is the business of a knowledgeable doctor. With this method of functional diagnostics, the following is evaluated:

• heart rhythm - the state of the generators of electrical impulses and the state of the heart system that conducts these impulses
• condition of the heart muscle itself (myocardium), the presence or absence of its inflammation, damage, thickening, oxygen starvation, electrolyte imbalance

However, modern patients often have access to their medical documents, in particular, to electrocardiography films on which medical reports are written. With their diversity, these records can bring even the most balanced, but ignorant person. Indeed, often the patient does not know for certain how dangerous for life and health what is written on the back of the ECG film by the hand of a functional diagnostician, and there are still a few days before an appointment with a therapist or cardiologist.

To reduce the intensity of passions, we immediately warn readers that with no serious diagnosis (myocardial infarction, acute rhythm disturbances), the functional diagnostician of the patient will not let the patient out of the office, but at least send him for a consultation with a specialist colleague right there. About the rest of the "secrets of the Open" in this article. In all unclear cases of pathological changes on the ECG, ECG control, daily monitoring (Holter), ECHO cardioscopy (ultrasound of the heart) and stress tests (treadmill, bicycle ergometry) are prescribed.

Numbers and Latin letters in ECG decoding

PQ- (0.12-0.2 s) - time of atrioventricular conduction. Most often, it lengthens against the background of AV blockade. Shortened in CLC and WPW syndromes.

P - (0.1s) height 0.25-2.5 mm describes atrial contractions. Can talk about their hypertrophy.

QRS - (0.06-0.1s) - ventricular complex

QT - (no more than 0.45 s) lengthens with oxygen starvation (myocardial ischemia, infarction) and the threat of rhythm disturbances.

RR - the distance between the apexes of the ventricular complexes reflects the regularity of heart contractions and makes it possible to calculate the heart rate.

The decoding of the ECG in children is shown in Fig. 3

Options for describing the heart rate

Sinus rhythm

This is the most common inscription found on the ECG. And, if nothing else is added and the frequency (HR) is indicated from 60 to 90 beats per minute (for example, heart rate 68`) - this is the most successful option, indicating that the heart works like a clock. This is the rhythm set by the sinus node (the main pacemaker that generates electrical impulses that cause the heart to contract). At the same time, sinus rhythm implies well-being, both in the state of this node, and the health of the conduction system of the heart. The absence of other records denies pathological changes in the heart muscle and means that the ECG is normal. In addition to sinus rhythm, it can be atrial, atrioventricular or ventricular, indicating that the rhythm is set by the cells in these parts of the heart and is considered pathological.

sinus arrhythmia

This is a variant of the norm in young people and children. This is a rhythm in which impulses exit the sinus node, but the intervals between heartbeats are different. This may be due to physiological changes (respiratory arrhythmia, when heart contractions slow down on exhalation). Approximately 30% of sinus arrhythmias require observation by a cardiologist, as they are threatened by the development of more serious rhythm disturbances. These are arrhythmias after rheumatic fever. Against the background of myocarditis or after it, against the background of infectious diseases, heart defects and in people with a history of arrhythmias.

Sinus bradycardia

These are rhythmic contractions of the heart with a frequency of less than 50 per minute. In healthy people, bradycardia occurs, for example, during sleep. Also, bradycardia is often seen in professional athletes. Pathological bradycardia may indicate sick sinus syndrome. At the same time, bradycardia is more pronounced (heart rate from 45 to 35 beats per minute on average) and is observed at any time of the day. When bradycardia causes pauses in heart contractions of up to 3 seconds during the day and about 5 seconds at night, leads to disruptions in the supply of oxygen to tissues and manifests itself, for example, by fainting, an operation is indicated to install a heart pacemaker, which replaces the sinus node, imposing a normal rhythm of contractions on the heart.

Sinus tachycardia

Heart rate more than 90 per minute - is divided into physiological and pathological. In healthy people, sinus tachycardia is accompanied by physical and emotional stress, drinking coffee, sometimes strong tea or alcohol (especially energy drinks). It is short-lived and after an episode of tachycardia, the heart rate returns to normal in a short period of time after the cessation of the load. With pathological tachycardia, palpitations disturb the patient at rest. Its causes are temperature rises, infections, blood loss, dehydration, anemia,. Treat the underlying disease. Sinus tachycardia is stopped only with a heart attack or acute coronary syndrome.

Extrasystole

These are rhythm disturbances, in which foci outside the sinus rhythm give extraordinary heart contractions, after which there is a pause doubled in length, called a compensatory one. In general, heartbeats are perceived by the patient as uneven, rapid or slow, sometimes chaotic. Most of all, failures in the heart rhythm are disturbing. They can occur in the form of jolts, tingling, feelings of fear and emptiness in the abdomen.

Not all extrasystoles are dangerous to health. Most of them do not lead to significant circulatory disorders and do not threaten either life or health. They can be functional (against the background of panic attacks, cardioneurosis, hormonal disruptions), organic (with IHD, heart defects, myocardial dystrophy or cardiopathy, myocarditis). They can also lead to intoxication and heart surgery. Depending on the place of occurrence, extrasystoles are divided into atrial, ventricular and antrioventricular (arising in a node on the border between the atria and ventricles).

• Single extrasystoles most often rare (less than 5 per hour). They are usually functional and do not interfere with the normal blood supply.
• Paired extrasystoles two each accompany a number of normal contractions. Such a rhythm disturbance often indicates pathology and requires additional examination (Holter monitoring).
• Allorhythmias are more complex types of extrasystoles. If every second contraction is an extrasystole, it is bigymenia, if every third is trigynemia, and every fourth is quadrihymenia.

It is customary to divide ventricular extrasystoles into five classes (according to Laun). They are evaluated during daily ECG monitoring, since the indicators of a conventional ECG in a few minutes may not show anything.

• Class 1 - single rare extrasystoles with a frequency of up to 60 per hour, emanating from one focus (monotopic)
• 2 - frequent monotopic more than 5 per minute
• 3 - frequent polymorphic (of different shapes) polytopic (from different foci)
• 4a - paired, 4b - group (trigymenia), episodes of paroxysmal tachycardia
• 5 - early extrasystoles

The higher the class, the more serious the violations, although today even grades 3 and 4 do not always require medical treatment. In general, if there are less than 200 ventricular extrasystoles per day, they should be classified as functional and not worry about them. With more frequent, ECHO of the COP is indicated, sometimes - MRI of the heart. They do not treat extrasystole, but the disease that leads to it.

Paroxysmal tachycardia

In general, paroxysm is an attack. Paroxysmal acceleration of the rhythm can last from several minutes to several days. In this case, the intervals between heartbeats will be the same, and the rhythm will increase over 100 per minute (on average from 120 to 250). There are supraventricular and ventricular forms of tachycardia. The basis of this pathology is the abnormal circulation of an electrical impulse in the conduction system of the heart. Such a pathology is subject to treatment. From home remedies to eliminate an attack:

• breath holding
• increased forced cough
• face immersion in cold water

WPW syndrome

Wolff-Parkinson-White syndrome is a type of paroxysmal supraventricular tachycardia. Named after the names of the authors who described it. At the heart of the appearance of tachycardia is the presence between the atria and ventricles of an additional nerve bundle, through which a faster impulse passes than from the main pacemaker.

As a result, an extraordinary contraction of the heart muscle occurs. The syndrome requires conservative or surgical treatment (with ineffectiveness or intolerance of antiarrhythmic tablets, with episodes of atrial fibrillation, with concomitant heart defects).

CLC - Syndrome (Clerk-Levy-Christesco)

It is similar in mechanism to WPW and is characterized by an earlier excitation of the ventricles compared to the norm due to an additional bundle along which the nerve impulse travels. The congenital syndrome is manifested by attacks of rapid heartbeats.

Atrial fibrillation

It can be in the form of an attack or a permanent form. It manifests itself in the form of flutter or atrial fibrillation.

Atrial fibrillation

Atrial fibrillation

When the heart flickers, it contracts completely irregularly (intervals between contractions of very different durations). This is due to the fact that the rhythm is not set by the sinus node, but by other atrial cells.

It turns out a frequency of 350 to 700 beats per minute. There is simply no full-fledged atrial contraction; the contracting muscle fibers do not provide effective filling of the ventricles with blood.

As a result, the release of blood by the heart worsens and organs and tissues suffer from oxygen starvation. Another name for atrial fibrillation is atrial fibrillation. Not all atrial contractions reach the ventricles of the heart, so the heart rate (and pulse) will either be below normal (bradysystole with a frequency of less than 60), or normal (normosystole from 60 to 90), or above normal (tachysystole more than 90 beats per minute). ).

An attack of atrial fibrillation is difficult to miss.

• It usually starts with a strong heartbeat.
• It develops as a series of absolutely non-rhythmic heartbeats with a high or normal frequency.
• The condition is accompanied by weakness, sweating, dizziness.
• The fear of death is very pronounced.
• There may be shortness of breath, general arousal.
• Sometimes observed.
• The attack ends with the normalization of the rhythm and the urge to urinate, in which a large amount of urine leaves.

To stop the attack, they use reflex methods, drugs in the form of tablets or injections, or resort to cardioversion (stimulation of the heart with an electric defibrillator). If an attack of atrial fibrillation is not eliminated within two days, the risks of thrombotic complications (pulmonary embolism, stroke) increase.

With a constant form of heartbeat flicker (when the rhythm is not restored either against the background of drugs or against the background of electrical stimulation of the heart), they become a more familiar companion of patients and are felt only with tachysystole (rapid irregular heartbeats). The main task when detecting signs of tachysystole of a permanent form of atrial fibrillation on the ECG is to slow down the rhythm to normosystole without trying to make it rhythmic.

Examples of recordings on ECG films:

• atrial fibrillation, tachysystolic variant, heart rate 160 in '.
• Atrial fibrillation, normosystolic variant, heart rate 64 in '.

Atrial fibrillation can develop in the program of coronary heart disease, against the background of thyrotoxicosis, organic heart defects, diabetes mellitus, sick sinus syndrome, intoxication (most often with alcohol).

atrial flutter

These are frequent (more than 200 per minute) regular atrial contractions and the same regular, but more rare ventricular contractions. In general, flutter is more common in the acute form and is better tolerated than flicker, since circulatory disorders are less pronounced. Trembling develops when:

• organic heart disease (cardiomyopathies, heart failure)
• after heart surgery
• on the background of obstructive pulmonary disease
• it almost never occurs in healthy people.

Clinically, flutter is manifested by rapid rhythmic heartbeat and pulse, swelling of the jugular veins, shortness of breath, sweating and weakness.

Conduction disorders

Normally, having formed in the sinus node, electrical excitation goes through the conduction system, experiencing a physiological delay of a fraction of a second in the atrioventricular node. On its way, the impulse stimulates the atria and ventricles, which pump blood, to contract. If in some part of the conduction system the impulse lingers longer than the prescribed time, then the excitation to the underlying sections will come later, which means that the normal pumping work of the heart muscle will be disrupted. Conduction disorders are called blockades. They can occur as functional disorders, but are more often the result of drug or alcohol intoxication and organic heart disease. Depending on the level at which they arise, there are several types of them.

Sinoatrial blockade

When the exit of the impulse from the sinus node is difficult. In fact, this leads to a syndrome of weakness of the sinus node, a decrease in contractions to severe bradycardia, impaired blood supply to the periphery, shortness of breath, weakness, dizziness and loss of consciousness. The second degree of this blockade is called the Samoilov-Wenckebach syndrome.

Atrioventricular block (AV block)

This is a delay in excitation in the atrioventricular node of more than the prescribed 0.09 seconds. There are three degrees of this type of blockade. The higher the degree, the less often the ventricles contract, the more severe the circulatory disorders.

• At the first delay allows each atrial contraction to maintain an adequate number of ventricular contractions.
• The second degree leaves part of the atrial contractions without ventricular contractions. It is described in terms of PQ prolongation and ventricular beat prolapse as Mobitz 1, 2, or 3.
• The third degree is also called a complete transverse block. The atria and ventricles begin to contract without interrelation.

In this case, the ventricles do not stop, because they obey the pacemakers from the underlying parts of the heart. If the first degree of blockade may not manifest itself in any way and be detected only with an ECG, then the second is already characterized by sensations of periodic cardiac arrest, weakness, fatigue. With complete blockades, cerebral symptoms (dizziness, flies in the eyes) are added to the manifestations. Morgagni-Adams-Stokes attacks may develop (when the ventricles escape from all pacemakers) with loss of consciousness and even convulsions.

Conduction disturbance within the ventricles

In the ventricles to the muscle cells, the electrical signal propagates through such elements of the conduction system as the trunk of the bundle of His, its legs (left and right) and the branches of the legs. Blockades can occur at any of these levels, which is also reflected in the ECG. In this case, instead of being covered by excitation at the same time, one of the ventricles is delayed, since the signal to it goes around the blocked area.

In addition to the place of origin, a complete or incomplete blockade is distinguished, as well as permanent and non-permanent. The causes of intraventricular blockades are similar to other conduction disorders (IHD, myo- and endocarditis, cardiomyopathies, heart defects, arterial hypertension, fibrosis, heart tumors). Also, the intake of antiarthmic drugs, an increase in potassium in the blood plasma, acidosis, and oxygen starvation also affect.

• The most common is the blockade of the anteroposterior branch of the left leg of the bundle of His (BPVLNPG).
• In second place is the blockade of the right leg (RBNB). This blockade is usually not accompanied by heart disease.
• Blockade of the left leg of the bundle of His more characteristic of myocardial damage. At the same time, complete blockade (PBBBB) is worse than incomplete blockade (NBLBBB). It sometimes has to be distinguished from the WPW syndrome.
• Blockade of the posterior inferior branch of the left leg of the bundle of His may be in persons with a narrow and elongated or deformed chest. Of the pathological conditions, it is more characteristic of right ventricular overload (with pulmonary embolism or heart defects).

The clinic of blockades at the levels of the bundle of His is not expressed. The picture of the main cardiac pathology comes first.

• Bailey's syndrome - two-beam blockade (of the right leg and posterior branch of the left leg of the bundle of His).

Myocardial hypertrophy

With chronic overloads (pressure, volume), the heart muscle in some areas begins to thicken, and the heart chambers stretch. On the ECG, such changes are usually described as hypertrophy.

• (LVH) - typical for arterial hypertension, cardiomyopathy, a number of heart defects. But even in normal athletes, obese patients and people engaged in heavy physical labor, there may be signs of LVH.
• Right ventricular hypertrophy- an undoubted sign of increased pressure in the pulmonary circulation system. Chronic cor pulmonale, obstructive pulmonary disease, cardiac defects (pulmonary stenosis, Fallot's tetralogy, ventricular septal defect) lead to HPZh.
• Left atrial hypertrophy (HLH)) - with mitral and aortic stenosis or insufficiency, hypertension, cardiomyopathy, after.
• Right atrial hypertrophy (RAH)- with cor pulmonale, tricuspid valve defects, chest deformities, pulmonary pathologies and pulmonary embolism.
• Indirect signs of ventricular hypertrophy is the deviation of the electrical axis of the heart (EOC) to the right or left. The left type of EOS is its deviation to the left, that is, LVH, the right type is LVH.
• Systolic overload- this is also evidence of hypertrophy of the heart. Less commonly, this is evidence of ischemia (in the presence of angina pain).

Changes in myocardial contractility and nutrition

Syndrome of early repolarization of the ventricles

Most often, it is a variant of the norm, especially for athletes and people with congenitally high body weight. Sometimes associated with myocardial hypertrophy. Refers to the peculiarities of the passage of electrolytes (potassium) through the membranes of cardiocytes and the characteristics of the proteins from which the membranes are built. It is considered a risk factor for sudden cardiac arrest, but it does not give a clinic and most often remains without consequences.

Moderate or severe diffuse changes in the myocardium

This is evidence of myocardial malnutrition as a result of dystrophy, inflammation () or. Also, reversible diffuse changes accompany disturbances in the water and electrolyte balance (with vomiting or diarrhea), taking medications (diuretics), and heavy physical exertion.

Nonspecific ST changes

This is a sign of deterioration in myocardial nutrition without pronounced oxygen starvation, for example, in violation of the balance of electrolytes or against the background of dyshormonal conditions.

Acute ischemia, ischemic changes, T wave changes, ST depression, low T

This describes the reversible changes associated with oxygen starvation of the myocardium (ischemia). It can be either stable angina or unstable, acute coronary syndrome. In addition to the presence of the changes themselves, their location is also described (for example, subendocardial ischemia). A distinctive feature of such changes is their reversibility. In any case, such changes require comparison of this ECG with old films, and if a heart attack is suspected, rapid troponin tests for myocardial damage or coronary angiography should be performed. Depending on the variant of coronary heart disease, anti-ischemic treatment is selected.

Developed heart attack

It is usually described as:

• by stages: acute (up to 3 days), acute (up to 3 weeks), subacute (up to 3 months), cicatricial (lifelong after a heart attack)
• by volume: transmural (large-focal), subendocardial (small-focal)
• according to the location of the infarction: there are anterior and anterior-septal, basal, lateral, lower (posterior diaphragmatic), circular apical, posterior basal and right ventricular.

In any case, a heart attack is a reason for immediate hospitalization.

All the variety of syndromes and specific ECG changes, the difference in indicators for adults and children, the abundance of reasons leading to the same type of ECG changes do not allow a non-specialist to interpret even a ready-made conclusion of a functional diagnostician. It is much more reasonable, having an ECG result in hand, to visit a cardiologist in a timely manner and receive competent recommendations for further diagnosis or treatment of your problem, significantly reducing the risks of emergency cardiac conditions.

The ECG machine was invented by an English scientist over a century ago. He recorded the electrical activity of the heart muscle and recorded this data on a special paper tape. Naturally, over the entire period of its existence, it has been modernized several times, but the basic principle of operation, which was based on the recording of electrical impulses, has remained unchanged.

Now he is in any hospital, they are equipped with ambulance teams and district therapists. Lightweight and mobile, the electrocardiograph helps save lives with the ability to quickly take an ECG. Speed ​​and accuracy are important for patients with pulmonary embolism, myocardial infarction, bradycardia, diseases that require emergency medical care.

Deciphering ECG indicators for an experienced doctor is not a problem. Many cardiac diagnoses are established on the basis of this monitoring, and most of them unmistakably indicate cardiovascular pathologies.

What you need to know about the principles of the ECG

An outside person, which is any patient of cardiology, is not able to understand the incomprehensible teeth and peaks displayed by the electrocardiograph recorder. It is difficult for people without special education to understand what the doctor sees there, but the general principles of the work of the heart are quite clear to everyone.

Man belongs to mammals and his heart consists of 4 chambers. These are two atria with thin walls that perform auxiliary work, and two ventricles, which withstand the main loads. There are certain differences between the right and left side of the heart. It is easier for the body to provide the right ventricle with blood from the pulmonary circulation than to push the blood into the systemic circle with the left. Therefore, the left is more developed, but there are more diseases that affect it. But despite this fundamental difference, human health largely depends on the coherence and uniformity of the work of all departments of the body.

In addition, the parts of the heart differ in their structure and intensity of electrical activity. The myocardium, that is, contractile complexes, and nerves, valves, adipose tissue, blood vessels, in fact, irreducible elements, differ in the degree and speed of response to electrical impulses.

Cardiologists recognize cardiac pathologies due to their deep knowledge of the principles of the heart and the ability to decipher the electrocardiogram. Intervals, waves, and leads must be considered in a single context that defines common heart conditions.

There are not so many specific functions of the heart, it has:

• Automatism, that is, spontaneously generates impulses, which lead to its excitation.
• Excitability responsible for the possibility of cardiac activation under the action of an exciting impulse.
• Conductivity. The heart can provide an impulse from the place of its origin to the contractile structure involved in the process.
• Contractility. This is the ability of the heart muscle to contract and relax under the control of the current impulse.
• Tonicity. When the heart in diastole does not lose shape and is able to provide constant activity according to the physiological cycle.

The calm state of the heart, called static polarization, is electrically neutral, and at the stage of generation and conduction of exciting impulses, which imply an electrical process, characteristic biocurrents are formed.

How to decipher the ECG: what does the doctor focus on

Now it is not difficult to carry out an ECG procedure; any hospital is equipped with these devices. But what is included in the complex of manipulations and what is usually regarded as the norm of states? The technique of conducting an electrocardiogram is familiar only to health workers who undergo an additional training cycle. The patient should be aware of the rules for preparing for an ECG. Before monitoring:

• Do not transfer.
• Stop smoking, drinking coffee and alcohol.
• Exclude medication.
• Avoid heavy physical exertion before the procedure.

All this will affect the results of the electrocardiogram in the form of tachycardia or more serious disorders. The patient, who is in a calm state, undresses to the waist, takes off his shoes and lies down on the couch. The sister treats the leads with a special solution, fixes the electrodes and takes readings. Then her data is transferred to the cardiologist for decoding.

Each wave on the ECG is designated as a capital Latin letter, P, Q, R, S, T, U.

• P - atrial depolarization. With a QRS complex, one speaks of depolarization of the ventricles.
• T - repolarization of the ventricles. A smeared U wave indicates repolarization of the distal conduction system.
• If the teeth are directed upwards, then they are positive, those that are directed downwards are negative. The Q and S waves will always be negative, and the R wave will always be positive.

12 leads are used to collect data:

• Standard: I, II, III.
• Reinforced unipolar limb leads - three.
• Reinforced unipolar chest - six.

With a pronounced arrhythmia or an abnormal location of the heart, there is a need to use additional chest leads, bipolar and unipolar (D, A, I).

Deciphering the results, the doctor measures the duration of the intervals between each of the ECG indicators. Thus, an assessment is made of the frequency of the rhythm, when the size and shape of the wave in a different lead determines the nature of the rhythm, the electrical phenomena occurring in the heart, and the electrical activity of each section of the myocardium. In fact, the ECG demonstrates the complex work of the heart in a single period.

Detailed interpretation of the ECG: norm, pathology and disease

If strict decoding is necessary, an analysis and calculation of the area of ​​​​the teeth is carried out using additional leads, according to the vector theory. But in everyday practice, much more often they resort to such an indicator as the direction of the electric axis. It is the total QRS vector. Naturally, each person has individual physiological features of the structure of the chest, and the heart can be displaced from its usual location. In addition, the ratio of the weight of the ventricles, the intensity and speed of conduction within them can also vary. Therefore, decoding requires a description of both the vertical and horizontal directions along this vector.

Decoding can only be carried out in a certain sequence, which helps to differentiate the indicators of the norm from the identified violations:

• The heart rate is assessed, the heart rate is measured. A normal ECG is characterized by sinus rhythm with a heart rate of 60-80 beats/minute.
• Intervals are calculated indicating the duration of systole (contraction phase). This is done using the special formula of Bazett. QT is normal - 390/450ms, if it lengthens, then they can diagnose IHD, myocarditis, rheumatism, atherosclerosis. If the interval is shortened, hypercalcemia is suspected. The intervals reflect the conductivity of impulses, it is calculated using special automatic programs, which only increases the diagnostic value of the results.
• The position of the EOS is calculated from the isoline and is guided by the height of the teeth. Under normal conditions, the R wave will always be higher than the S wave. And if, on the contrary, with a simultaneous deviation of the axis to the right, then functional failures in the right ventricle are assumed. With a deviation of the axis to the left, respectively, to the left, provided that S is greater than R in leads II and III. This indicates left ventricular hypertrophy.
• Explore the QRS complex formed during the conduction of impulses to the muscles of the ventricles. The complex determines the functional load of the ventricles. In the normal state, there is no pathological Q wave, and the width of the entire complex does not exceed 120 ms. With a shift in this interval, a diagnosis of complete or partial blockade of the legs of the His bundle is made or they speak of conduction disorders. Incomplete blockade of the right leg acts as an electrocardiographic indicator of hypertrophic changes in the right ventricle, and incomplete blockade of the left leg is evidence of left ventricular hypertrophy.
• ST segments are described, reflecting the period of recovery of the initial state of the heart muscle from the moment of its complete depolarization. Normally, they are on the isoline. As well as the T wave, which reflects the process of ventricular repolarization. The process is directed upwards, with asymmetry, and its amplitude should normally be below the T wave. It is longer than the QRS complex in duration.

A full decoding can only be done by a doctor, but if necessary, an ambulance paramedic can also do this.

Deviations from the norm: physiological aspects

This is an image of a normal ECG of a healthy person. His heart is working smoothly, with a regular rhythm and correctly. But these indicators can change and vary under different physiological conditions. One such condition is pregnancy. In women bearing a child, the heart is somewhat displaced relative to the normal anatomical location in the chest, and therefore the electrical axis is also displaced. It all depends on the period, since every month increases the load on the heart. During pregnancy, all these changes will be displayed on the ECG, but will be regarded as a conditional norm.

The children's cardiogram is also different, the indicators of which change according to age as the child grows. And only after 12 years, the ECG of children begins to resemble the GCG of adults.

Sometimes there are situations when two ECGs for the same patient, made even with a difference of only a few hours, are strikingly different. Why is this happening? To get accurate results, you need to take into account many influencing factors:

• A distorted ECG recording may be the result of a device malfunction or other technical problems. For example, if the results were incorrectly glued together by a health worker. It should be noted that some Roman designations look identical both inverted and in the normal position. There are situations when the graph is cut incorrectly, which leads to the loss of the last or first tooth.
• It is also important how well the patient prepared. Anything that stimulates the heart rate will certainly affect the ECG results. Before the procedure, it is desirable to take a shower, but you can not use cosmetics for the body. And in the process of removing the cardiogram, the patient should be in a relaxed state.
• It is impossible to exclude the possibility of incorrect location of the electrodes.

It is best to trust the heart check to electrocardiographs, they carry out the analysis with maximum accuracy. To confirm the diagnosis found on the ECG, the doctor always prescribes several additional studies.