Norms of ecg in ms. Cardiogram of the heart decoding, norm, photo

Electrocardiography is considered the simplest method for determining the quality of the heart, both in normal and pathological conditions. The essence of this method is to capture and fix the electrical impulses of the heart that occur during its work.

But in order to determine the degree of violation, decoding is necessary. ECG of the heart, since the fixation of these impulses is performed using a specific graphic image for a certain time.

Indications for an ECG:

1. For preventive purposes;
2. Directed determination of the frequency of contractions of the heart muscle and the rhythm of the work of the organ;
3. Definition of acute and chronic heart failure;
4. Identification of various conduction disorders inside the heart;
5. For the purpose of determining physical condition hearts;
6. Diagnostics ;
7. Obtaining information about pathologies that occur outside the heart (for example, complete or partial).

Principles of ECG decoding

Three main indicators are schematically shown on the electrocardiogram:

1. Teeth - bulges with an acute angle, directed up or down and are designated P, Q, R, S, T;
2. Segments - are the distance between adjacent teeth;
3. An interval is a gap that includes both a tooth and a segment.

Thanks to the above indicators, the cardiologist determines the level of contraction and recovery of the heart muscle. In addition to these indicators, during the electrocardiogram, the electrical axis of the heart can also be determined, which indicates the approximate location of the organ in the chest cavity. The latter depends on the constitution of the human body and chronic pathology. The electrical axis of the heart can be: normal, vertical and horizontal.

Key indicators of ECG decoding

When deciphered, the indicators of the norm will be as follows:

1. The distance between the R and R waves should be even throughout the cardiogram;
2. The intervals between PQRST should be between 120 and 200 m/s, graphically this is determined by 2-3 squares. This is an indicator of the passage of the impulse through all cardiac departments from the atria to the ventricles;
3. The interval between Q and S indicates the passage of the impulse through the ventricles (60-100 m/s);
4. The duration of ventricular contractility is determined using Q and T, normally 400-450 m/s;

At the slightest shift from these parameters, one can judge the beginning or development of a pathological process in the heart muscle. Such parameters are especially pronounced in rheumatism.

It should also be noted that in some cases, the ECG decoding norms may vary slightly due to the presence of some disorders that are considered normal, since their presence does not affect the development of heart failure (for example, respiratory arrhythmia). It is important to note that for ECG decoding in adults, the norm can be presented in different tables describing the speed of passage between the elements of the cardiogram.

Ecg decoding in adults is the norm in the table

Ecg decoding norm table

Such tables are an official document for determining possible pathological changes in the heart muscle.

Video: ECG interpretation

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 peak value, the age of the patient, the presence or absence of aggravating factors, etc.

ECG of the heart for diabetics who, in addition to diabetes there are also late cardiovascular complications that make it possible to assess the severity of the disease and intervene in time in order to delay the further progression of the disease, which can lead to serious consequences in the form of myocardial infarction, pulmonary embolism, 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 somewhat different, since a natural shift occurs in the process of fetal growth internal organs 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 medicines heart stimulants or suppressants, 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 ECG 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.

ECG norm young man(age 20 - 30 years).

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

• Evaluation in progress heart rate with measurement of heart rate (heart rate) at normal: 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, 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 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 designated by the letter V. The recording electrode mounted on right hand, is indicated by the sign VR, to 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 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 duration interval Q-R-S which is in the normal range.

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 right leg 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.

By coronary arteries a blood flow goes to the heart, which, with an increase in the thickness of the myocardium, encounters an obstacle in 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 it starts chain reaction because the work of one department depends on the work of other departments. 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

With sinus rhythm, left ventricular hypertrophy is clearly visible with characteristic high T waves in 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 kidney 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; interval P-Q more 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 same interval teeth P-P. 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 portable device, capable for a long period of time to fix the signals coming through the electrodes on the magnetic tape.

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.

Painless symptoms are usually the basis for this type of analysis. coronary disease heart, 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 you can notice even the slightest pathological changes in the work of the heart, and it is widely used in medical practice in order to identify life-threatening diseases in patients such as 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.

The electrocardiogram of the heart is the main diagnostic study that allows you to draw conclusions about the work of the organ, the presence or absence of pathologies and their severity. ECG interpretation heart examination is carried out by a cardiologist, who sees not only the curves on paper, but can also visually assess the patient's condition, analyze his complaints.

The indicators collected all together help to make the correct diagnosis. Without an accurate diagnosis, it is impossible to prescribe effective treatment, so doctors are especially careful to study ECG results patient.

Brief information about the ECG procedure

Electrocardiography examines the electrical currents that occur during the work of the human heart. This method is quite simple and affordable - these are the main advantages diagnostic procedure, which has been carried out by doctors for a long time and with regard to the interpretation of the results, doctors have accumulated sufficient practical experience.

The cardiogram of the heart was developed and implemented in its modern form at the beginning of the twentieth century by the Dutch scientist Einthoven. The terminology developed by the physiologist is still used today. This once again proves that the ECG is a relevant and in-demand study, the indicators of which are extremely important for diagnosing heart pathologies.

The value of the cardiogram

An electrocardiogram is extremely important, since its correct reading allows you to detect the most serious pathologies, the patient's life depends on the timely diagnosis of which. A cardiogram is performed in both adults and children.

Upon receipt of the results, a cardiologist can evaluate the heart rate, the presence of arrhythmia, metabolic pathology in the myocardium, electrical conduction disturbance, myocardial pathology, localization of the electrical axis, the physiological state of the main human organ. In some cases, the cardiogram can confirm other somatic pathologies that are indirectly related to cardiac activity.

Important! Doctors recommend doing a cardiogram if the patient feels obvious changes in heart rhythm, suffers from sudden shortness of breath, weakness, and faints. It is necessary to do a cardiogram for primary pains in the heart, as well as for those patients who have already been diagnosed with abnormalities in the work of the organ, noises are observed.

An electrocardiogram is a standard procedure during a medical examination, in athletes during a medical examination, in pregnant women, before surgical interventions. Diagnostic value has an ECG with and without exercise. Make a cardiogram for pathologies of the endocrine and nervous systems with an increase in lipid levels. For the purpose of prevention, it is recommended to make a heart diagnosis for all patients who have reached forty-five years of age - this will help to identify abnormal performance of the organ, diagnose pathology and begin therapy.

What are the results of the study?

The results of the study for dummies will be absolutely incomprehensible, therefore it is impossible to read the cardiogram of the heart on your own. The doctor receives from the electrocardiograph a long millimeter paper with curves printed on it. Each graph reflects an electrode attached to the patient's body at a certain point.

In addition to graphs, devices can also provide other information, for example, the main parameters, the rate of one or another indicator. A preliminary diagnosis is generated automatically, so the doctor needs to independently study the results and only take into account what the device gives out in terms of possible disease. Data can be recorded not only on paper, but also on electronic media, as well as in the memory of the device.

Interesting! Holter monitoring is a type of ECG. If the cardiogram is taken in the clinic in a few minutes while the patient is lying down, then with Holter monitoring, the patient receives a portable sensor, which he attaches to his body. It is necessary to wear the sensor for a full day, after which the doctor reads the results. The peculiarity of such monitoring is the dynamic study of cardiac activity in different states. This allows you to get a more complete picture of the patient's health status.

Deciphering the results of the study: main aspects

Curves on graph paper are represented by isolines - a straight line, which means that there are no impulses at the moment. Deviations up or down from the isoline are called teeth. In one complete cycle heart contraction six teeth are laid, which are assigned standard letters of the Latin alphabet. Such teeth on the cardiogram are either directed up or down. The upper teeth are considered to be positive, and the downward ones are considered negative. Normally, the S and Q waves dip slightly down from the isoline, and the R wave is a peak rising upward.

Each tooth is not just a drawing with a letter, behind it lies a certain phase of the heart. You can decipher the cardiogram if you know which teeth mean what. For example, the P wave demonstrates the moment when the atria are relaxed, R indicates the excitation of the ventricles, and T indicates their relaxation. Doctors take into account the distance between the teeth, which also has its diagnostic value, and if necessary, entire groups of PQ, QRS, ST are examined. Each research value speaks about a certain characteristic of the organ.

For example, with an unequal distance between the R teeth, doctors talk about extrasystole, atrial fibrillation, weakness of the sinus node. If the P wave is elevated and thickened, then this indicates a thickening of the walls of the atria. An extended PQ interval indicates artrioventricular block, and an expansion of the QRS suggests ventricular hypertrophy, blockade of the His bundle. If there are no gaps in this segment, doctors suspect fibrillation. A prolonged QT interval indicates serious heart rhythm disturbances that can be fatal. And if this combination of QRS is presented as a flag, then doctors talk about myocardial infarction.

Table of normal values ​​\u200b\u200band other indicators

To decipher the ECG, there is a table containing the norms of values. Focusing on it, doctors can see deviations. As a rule, in the process of long work with cardiological patients, doctors no longer use the table at hand, the norm in adults is memorized by heart.

Indicator Amplitude of the norm, s QRS from 0.06 to 0.1 Rot 0.07 to 0.11 Q from 0.07 to 0.11 T from 0.12 to 0.28 PQ from 0.12 to 0.2

In addition to tabular values, doctors consider other parameters of the work of the heart:

• rhythmicity of heart contractions - in the presence of arrhythmia, i.e. failures in the rhythmicity of contractions of the heart muscle, the difference between the indicators of the teeth will be more than ten percent. In people with a healthy heart, normosistolia is noted, but pathological data make the doctor alert and look for deviations. The exception is sinus arrhythmia in combination with sinus rhythm, as is often the case in adolescence However, in adults, sinus rhythm with deviations indicates the beginning of the development of pathology. A striking example of deviations is extrasystole, which manifests itself in the presence of additional contractions. It occurs with malformations of the heart, inflammation of the myocardium, ischemia,
• heart rate is the most accessible parameter, it can be assessed independently. Normally, in one minute there should be from 60 to 80 complete cycles of the heart. With a rapid cycle, more than 80 beats speak of tachycardia, but less than 60 is bradycardia. The indicator is more illustrative, since not all severe pathologies give bradycardia or tachycardia, and in single cases, ECG will also show such phenomena. healthy person if he is nervous during the electrocardiography.

Types of heart rate

An electrocardiogram shows another important parameter - the type of heart rhythm. It means the place where the signal propagates, prompting the heart to contract.

There are several rhythms - sinus, atrial, ventricular and atrioventricular. The norm is sinus rhythm, and if the impulse occurs in other places, then this is considered a deviation.

An atrial rhythm on an ECG is a nerve impulse that occurs in the atria. Atrial cells provoke the appearance of ectopic rhythms. Such a situation arises when the sinus node malfunctions, which should produce these rhythms on its own, and now the atrial innervation centers do it for it. The immediate cause of this deviation is hypertension, weakness of the sinus node, ischemic disorders, and some endocrine pathologies. With such an ECG, non-specific ST-T changes. In some cases, atrial rhythm is observed in healthy people.

The atrioventricular rhythm occurs in the node of the same name. The pulse rate with this type of rhythm falls below 60 beats / min, indicating bradycardia. Causes of atrioventricular rhythm - a weak sinus node, taking certain medications, blockade of the AV node. If tachycardia occurs with atrioventricular rhythm, this is evidence of a previous heart attack, rheumatic changes, such a deviation appears after surgical interventions on the heart.

Ventricular rhythm is the most severe pathology. The impulse emanating from the ventricles is extremely weak, the contractions often fall below forty beats. Such a rhythm occurs with a heart attack, circulatory failure, cardiosclerosis, heart defects, in a preadgonal state.

Deciphering the analysis, doctors pay attention to the electrical axis. It is displayed in degrees and shows the direction of the impulses. The norm for this indicator is 30-70 degrees when tilted to the vertical. Abnormalities suggest intracardiac blockade or hypertension.

When deciphering the ECG, terminological conclusions are issued, which also demonstrate the norm or pathology. A bad ECG or a result without pathology will show in a complex all indicators of the work of the heart. Atrioventricular block will be reflected as a prolonged PQ interval. Such a deviation in the first degree does not threaten the life of the patient. But with the third degree of pathology, there is a risk of sudden cardiac arrest, since the atria and ventricles work in their own incongruous rhythm.

If the conclusion contains the word "ectopic rhythm", this means that the innervation does not come from the sinus node. The condition is both a variant of the norm and a severe deviation due to cardiac pathologies, taking medicines etc.

If the cardiogram shows nonspecific ST-T wave changes, then this situation requires additional diagnostics. The reason for the deviation may be metabolic disorders, an imbalance of basic electrolytes, or endocrine dysfunctions. A high T wave may indicate hypokalemia, but is also a normal variant.

With some pathologies of the heart, the conclusion will show a low voltage - the currents emanating from the heart are so weak that they are recorded below normal. Low electrical activity is due to pericarditis or other cardiac pathologies.

Important! The borderline ECG of the heart indicates a deviation of some parameters from the norm. This output is generated by the electrocardiograph system and does not mean at all severe violations. Upon receipt of such data, patients should not be upset - it is enough just to undergo an additional examination, identify the cause of the violations and treat the underlying disease.

Myocardial infarction on ECG

An ECG in myocardial infarction records extremely important diagnostic data, according to which it is possible not only to diagnose a heart attack, but also to determine the severity of the violations. The manifestation of pathology on the ECG will be noticeable already with the onset of symptoms of a crisis. There will be no R wave on the tape - this is one of the leading signs of myocardial infarction.

Electrocardiography is one of the most common and most informative methods for diagnosing a huge number of diseases. An ECG involves a graphical display of electrical potentials that are formed in a beating heart. The removal of indicators and their display is carried out by means of special devices - electrocardiographs, which are constantly being improved.

As a rule, during the study, 5 teeth are fixed: P, Q, R, S, T. At some points, it is possible to fix an inconspicuous U wave.

Electrocardiography allows you to identify the following indicators, as well as options for deviations from the reference values:

• Heart rate (pulse) and regularity of myocardial contractions (arrhythmias and extrasystoles can be detected);
• Violations in the heart muscle of an acute or chronic nature (in particular, with ischemia or infarction);
• metabolic disorders of the main compounds with electrolytic activity (K, Ca, Mg);
• violations of intracardiac conduction;
• hypertrophy of the heart (atria and ventricles).

Note:when used in parallel with a cardiophone, the electrocardiograph provides the ability to remotely determine some acute diseases heart (the presence of areas of ischemia or heart attacks).

ECG is the most important screening technique for detecting coronary artery disease. Valuable information is provided by electrocardiography with the so-called. "load tests".

In isolation or in combination with other diagnostic methods, ECG is often used in the study of cognitive (mental) processes.

Important:an electrocardiogram must be taken during the medical examination, regardless of age and general condition patient.

ECG: indications for holding

There are a number of pathologies of cardio-vascular system and other organs and systems in which an electrocardiographic study is prescribed. These include:

• angina;
• myocardial infarction;
• reactive arthritis;
• peri- and myocarditis;
• nodular periarteritis;
• arrhythmias;
• acute renal failure;
• diabetic nephropathy;
• scleroderma.

With hypertrophy of the right ventricle, the amplitude of the S wave in leads V1-V3 increases, which may be an indicator of symmetrical pathology from the left ventricle.

With left ventricular hypertrophy, the R wave is pronounced in the left chest leads and its depth is increased in leads V1-V2. The electrical axis is either horizontal or deviated to the left, but it can often correspond to the norm. The QRS complex in lead V6 has a qR or R shape.

Note:this pathology is often accompanied by secondary changes in the heart muscle (dystrophy).

Left atrial hypertrophy is characterized by a rather significant increase in the P wave (up to 0.11-0.14 s). It acquires a "double-humped" shape in the left chest leads and leads I and II. In rare clinical cases, there is some flattening of the tooth, and the duration of the internal deviation of P exceeds 0.06 s in leads I, II, V6. Among the most prognostic evidence of this pathology is an increase in the negative phase of the P wave in lead V1.

Hypertrophy of the right atrium is characterized by an increase in the amplitude of the P wave (over 1.8-2.5 mm) in leads II, III, aVF. This tooth acquires a characteristic pointed shape, and the electrical axis P is installed vertically or has some shift to the right.

Combined atrial hypertrophy is characterized by a parallel expansion of the P wave and an increase in its amplitude. In some clinical cases, changes such as sharpness of P in leads II, III, aVF and splitting of the apex in I, V5, V6 are noted. In lead V1, an increase in both phases of the P wave is occasionally recorded.

For heart defects formed during fetal development, a significant increase in the amplitude of the P wave in leads V1-V3 is more characteristic.

In patients with severe chronic cor pulmonale with emphysematous lung disease, as a rule, an S-type ECG is determined.

Important:combined hypertrophy of two ventricles at once is rarely determined by electrocardiography, especially if the hypertrophy is uniform. In this case, pathological signs tend to be mutually compensated, as it were.

With "syndrome of premature excitation of the ventricles" on the ECG, the width of the QRS complex increases and the R-R interval becomes shorter. The delta wave, which affects the increase in the QRS complex, is formed as a result of an early increase in the activity of sections of the heart muscle of the ventricles.

Blockades are caused by the termination of the conduction of an electrical impulse in one of the sections.

Violations of impulse conduction are manifested on the ECG by a change in the shape and an increase in the size of the P wave, and with intraventricular blockade - an increase in QRS. Atrioventricular blockade may be characterized by the loss of individual complexes, an increase in P-Q interval and, in the most severe cases, total absence connections between QRS and R.

Important:sinoatrial blockade appears on the ECG as a rather bright picture; it is characterized by the complete absence of the PQRST complex.

In case of heart rhythm disturbances, the evaluation of electrocardiography data is carried out on the basis of analysis and comparison of intervals (inter- and intra-cycle) for 10-20 seconds or even longer.

An important diagnostic value in the diagnosis of arrhythmias is the direction and shape of the P wave, as well as the QRS complex.

Myocardial dystrophy

This pathology is visible only in some leads. It is manifested by changes in the T wave. As a rule, its pronounced inversion is observed. In some cases, a significant deviation from the normal RST line is recorded. Pronounced dystrophy of the heart muscle is often manifested by a pronounced decrease in the amplitude of the QRS and P waves.

If a patient develops an angina attack, then a noticeable decrease (depression) in RST is recorded on the electrocardiogram, and in some cases, inversion of T. These changes on the ECG reflect ischemic processes in the intramural and subendocardial layers of the cardiac muscle of the left ventricle. These areas are the most demanding for blood supply.

Note:short-term rise of the RST segment is hallmark pathology known as Prinzmetal's angina.

Approximately 50% of patients in the intervals between angina attacks, changes in the ECG may not be recorded at all.

In this life-threatening condition, an electrocardiogram makes it possible to obtain information about the extent of the lesion, its exact location and depth. In addition, the ECG allows you to track the pathological process in dynamics.

Morphologically, it is customary to distinguish three zones:

• central (zone of necrotic changes in myocardial tissue);
• the zone of the expressed dystrophy of a cardiac muscle surrounding the center;
• peripheral zone of pronounced ischemic changes.

All changes that are reflected in the ECG dynamically change according to the stage of development of myocardial infarction.

Dishormonal myocardial dystrophy

Myocardial dystrophy, caused by a sharp change in the hormonal background of the patient, as a rule, is manifested by a change in the direction (inversions) of the T wave. Depressive changes in the RST complex are much less common.

Important: The severity of changes over time may vary. Pathological changes recorded on the ECG are only in rare cases associated with such clinical symptoms as pain in the chest area.

To distinguish manifestations of coronary artery disease from myocardial dystrophy against a background of hormonal imbalance, cardiologists practice tests using such pharmacological agents, as blockers of β-adrenergic receptors and potassium-containing drugs.

Changes in the electrocardiogram parameters against the background of the patient taking certain medications

Changes in the ECG picture can give the reception of the following drugs:

• drugs from the group of diuretics;
• agents related to cardiac glycosides;
• amiodarone;
• Quinidine.

In particular, if the patient takes digitalis preparations (glycosides) in the recommended doses, then the relief of tachycardia (rapid heartbeat) and a decrease in the QT interval are determined. “Smoothing” of the RST segment and shortening of T cannot be excluded. Overdose of glycosides is manifested by such serious changes as arrhythmia (ventricular extrasystoles), AV blockade, and even life threatening condition - ventricular fibrillation (requires immediate resuscitation).

Pathology causes an excessive increase in the load on the right ventricle, and leads to its oxygen starvation and rapidly growing dystrophic changes. In such situations, the patient is diagnosed with acute cor pulmonale. In the presence of thromboembolism pulmonary arteries frequent blockade of the branches of the bundle of His.

On the ECG, the rise of the RST segment is recorded in parallel in leads III (sometimes in aVF and V1.2). There is an inversion of T in leads III, aVF, V1-V3.

Negative dynamics is growing rapidly (a matter of minutes pass), and progression is noted within 24 hours. With positive dynamics, the characteristic symptoms gradually stop within 1-2 weeks.

Early repolarization of the cardiac ventricles

This deviation is characterized by an upward shift of the RST complex from the so-called. isolines. Another characteristic feature is the presence of a specific transition wave on the R or S waves. These changes on the electrocardiogram are not yet associated with any myocardial pathology, therefore they are considered a physiological norm.

Pericarditis

Acute inflammation of the pericardium is manifested by a significant unidirectional rise of the RST segment in any leads. In some clinical cases, the shift may be discordant.

Myocarditis

Inflammation of the heart muscle is noticeable on the ECG with deviations from the T wave. They can vary from a decrease in voltage to an inversion. If, in parallel, a cardiologist conducts tests with potassium-containing agents or β-blockers, then the T wave remains in a negative position.

Cardiology
Chapter 5

in. Conduction disorders. Blockade of the anterior branch of the left leg of the bundle of His, blockade of the posterior branch of the left leg of the bundle of His, complete blockade of the left leg of the bundle of His, blockade of the right leg of the bundle of His, AV blockade of the 2nd degree and complete AV blockade.

G. Arrhythmias see Ch. four.

VI. Electrolyte disorders

BUT. Hypokalemia. Prolongation of the PQ interval. Expansion of the QRS complex (rare). Pronounced U wave, flattened inverted T wave, ST segment depression, slight QT prolongation.

B. Hyperkalemia

Light(5.56.5 meq/l). High peaked symmetrical T wave, shortening of the QT interval.

Moderate(6.58.0 meq/l). Reducing the amplitude of the P wave; prolongation of the PQ interval. Expansion of the QRS complex, a decrease in the amplitude of the R wave. Depression or elevation of the ST segment. Ventricular extrasystole.

heavy(911 meq/l). Absence of a P wave. Expansion of the QRS complex (up to sinusoidal complexes). Slow or accelerated idioventricular rhythm, ventricular tachycardia, ventricular fibrillation, asystole.

AT. Hypocalcemia. Prolongation of the QT interval (due to lengthening of the ST segment).

G. Hypercalcemia. Shortening of the QT interval (due to shortening of the ST segment).

VII. The action of drugs

BUT. cardiac glycosides

therapeutic action. Prolongation of the PQ interval. Sloping ST segment depression, shortening of the QT interval, T wave changes (flattened, inverted, biphasic), pronounced U wave. Decrease in heart rate with atrial fibrillation.

toxic action. Ventricular extrasystole, AV block, atrial tachycardia with AV block, accelerated AV nodal rhythm, sinoatrial block, ventricular tachycardia, bidirectional ventricular tachycardia, ventricular fibrillation.

BUT. dilated cardiomyopathy. Signs of an increase in the left atrium, sometimes right. Low amplitude of the teeth, pseudo-infarction curve, blockade of the left leg of the bundle of His, the anterior branch of the left leg of the bundle of His. Nonspecific changes in the ST segment and T wave. Ventricular extrasystole, atrial fibrillation.

B. Hypertrophic cardiomyopathy. Signs of an increase in the left atrium, sometimes right. Signs of left ventricular hypertrophy, pathological Q waves, pseudoinfarction curve. Nonspecific changes in the ST segment and T wave. With apical hypertrophy of the left ventricle, giant negative T waves in the left chest leads. Supraventricular and ventricular arrhythmias.

AT. amyloidosis of the heart. Low amplitude of the teeth, pseudo-infarction curve. Atrial fibrillation, AV block, ventricular arrhythmias, sinus node dysfunction.

G. Duchenne myopathy. Shortening of the PQ interval. High R wave in leads V 1 , V 2 ; deep Q wave in leads V 5 , V 6 . Sinus tachycardia, atrial and ventricular extrasystole, supraventricular tachycardia.

D. mitral stenosis. Signs of enlargement of the left atrium. There is hypertrophy of the right ventricle, deviation of the electrical axis of the heart to the right. Often - atrial fibrillation.

E. Mitral valve prolapse. T waves are flattened or inverted, especially in lead III; ST segment depression, slight prolongation of the QT interval. Ventricular and atrial extrasystole, supraventricular tachycardia, ventricular tachycardia, sometimes atrial fibrillation.

AND. Pericarditis. Depression of the PQ segment, especially in leads II, aVF, V 2 V 6 . Diffuse ST-segment elevation with upward bulge in leads I, II, aVF, V 3 V 6 . Sometimes ST segment depression in lead aVR (in rare cases in leads aVL, V 1 , V 2). Sinus tachycardia, atrial arrhythmias. ECG changes go through 4 stages:

ST segment elevation, T wave normal;

the ST segment descends to the isoline, the amplitude of the T wave decreases;

ST segment on the isoline, T wave inverted;

the ST segment is on the isoline, the T wave is normal.

Z. Large pericardial effusion. Low amplitude of the teeth, alternation of the QRS complex. Pathognomonic sign complete electrical alternation (P, QRS, T).

AND. Dextrocardia. The P wave is negative in lead I. QRS complex inverted in lead I, R/S< 1 во всех грудных отведениях с уменьшением амплитуды комплекса QRS от V 1 к V 6 . Инвертированный зубец T в I отведении.

TO. Atrial septal defect. Signs of an increase in the right atrium, less often left; prolongation of the PQ interval. RSR" in lead V 1; the electrical axis of the heart is deviated to the right with a defect of the ostium secundum type, to the left with a defect of the ostium primum type. Inverted T wave in leads V 1, V 2. Sometimes atrial fibrillation.

L. Stenosis of the pulmonary artery. Signs of enlargement of the right atrium. Right ventricular hypertrophy with high R wave in leads V 1 , V 2 ; deviation of the electrical axis of the heart to the right. Inverted T wave in leads V 1 , V 2 .

M. Sick sinus syndrome. Sinus bradycardia, sinoatrial block, AV block, sinus arrest, bradycardia-tachycardia syndrome, supraventricular tachycardia, atrial fibrillation/flutter, ventricular tachycardia.

IX. Other diseases

BUT. COPD. Signs of enlargement of the right atrium. Deviation of the electrical axis of the heart to the right, shift of the transition zone to the right, signs of right ventricular hypertrophy, low amplitude of the teeth; ECG type S I S II S III . T wave inversion in leads V 1 , V 2 . Sinus tachycardia, AV nodal rhythm, conduction disturbances, including AV block, intraventricular conduction delay, bundle branch block.

B. TELA. Syndrome S I Q III T III, signs of overload of the right ventricle, transient complete or incomplete blockade of the right bundle branch block, displacement of the electrical axis of the heart to the right. T wave inversion in leads V 1 , V 2 ; nonspecific changes in the ST segment and T wave. Sinus tachycardia, sometimes atrial rhythm disturbances.

AT. Subarachnoid hemorrhage and other CNS lesions. Sometimes pathological Q wave. High wide positive or deep negative T wave, elevation or depression of the ST segment, pronounced U wave, pronounced prolongation of the QT interval. Sinus bradycardia, sinus tachycardia, AV junctional rhythm, ventricular extrasystole, ventricular tachycardia.

G. Hypothyroidism. Prolongation of the PQ interval. Low amplitude of the QRS complex. Flattened T wave. Sinus bradycardia.

D. HPN. ST segment elongation (due to hypocalcemia), high symmetrical T waves (due to hyperkalemia).

E. Hypothermia. Prolongation of the PQ interval. A notch at the end of the QRS complex (Osborn's wave see). Prolongation of the QT interval, T wave inversion. Sinus bradycardia, atrial fibrillation, AV nodal rhythm, ventricular tachycardia.

THE EX . The main types of pacemakers are described by a three-letter code: the first letter indicates which chamber of the heart is being stimulated (A A trium atrium, V V entricle ventricle, D D ual and atrium and ventricle), the second letter which chamber activity is perceived (A, V or D), the third letter indicates the type of response to the perceived activity (I I nhibition blocking, T T riggering start, D D ual both). So, in the VVI mode, both the stimulating and sensing electrodes are located in the ventricle, and when spontaneous activity of the ventricle occurs, its stimulation is blocked. In DDD mode, both the atrium and the ventricle have two electrodes (stimulating and sensing). Response type D means that if spontaneous atrial activity occurs, its stimulation will be blocked, and after a programmed time interval (AV-interval), a stimulus will be given to the ventricle; if spontaneous ventricular activity occurs, on the contrary, ventricular pacing will be blocked, and atrial pacing will start after a programmed VA interval. Typical modes of a single-chamber pacemaker VVI and AAI. Typical two-chamber EKS modes DVI and DDD. The fourth letter R ( R ate-adaptive adaptive) means that the pacemaker is able to increase the pacing rate in response to changes in motor activity or load-dependent physiological parameters (eg, QT interval, temperature).

BUT. General principles of ECG interpretation

Assess the nature of the rhythm (own rhythm with periodic activation of the stimulator or imposed).

Determine which chamber(s) is being stimulated.

Determine the activity of which chamber(s) is perceived by the stimulator.

Determine programmed pacer intervals (VA, VV, AV intervals) from atrial (A) and ventricular (V) pacing artifacts.

Determine the EX mode. It must be remembered that ECG signs of a single-chamber ECS do not exclude the possibility of the presence of electrodes in two chambers: for example, stimulated contractions of the ventricles can be observed both with single-chamber and dual-chamber ECS, in which ventricular stimulation follows a certain interval after the P wave (DDD mode) .

Rule out violations of imposition and detection:

a. imposition disorders: there are stimulation artifacts that are not followed by depolarization complexes of the corresponding chamber;

b. detection disturbances: There are pacing artifacts that should be blocked if atrial or ventricular depolarization is normally detected.

B. Separate EKS modes

AAI. If the intrinsic rate falls below the programmed pacer rate, atrial pacing is initiated at a constant AA interval. With spontaneous atrial depolarization (and normal detection), the pacemaker time counter is reset. If spontaneous atrial depolarization does not recur after the set AA interval, atrial pacing is initiated.

VVI. With spontaneous ventricular depolarization (and normal detection), the pacemaker time counter is reset. If spontaneous ventricular depolarization does not recur after a predetermined VV interval, ventricular pacing is initiated; otherwise, the time counter is reset again and the whole cycle starts over. In adaptive VVIR pacemakers, the rhythm rate increases with increasing physical activity (up to a given upper limit of heart rate).

DDD. If the intrinsic rate falls below the programmed pacemaker rate, atrial (A) and ventricular (V) pacing is initiated at the specified intervals between the A and V pulses (AV interval) and between the V pulse and the subsequent A pulse (VA interval). With spontaneous or forced ventricular depolarization (and its normal detection), the pacemaker time counter is reset and the VA interval begins. If spontaneous atrial depolarization occurs in this interval, atrial pacing is blocked; otherwise, an atrial impulse is delivered. With spontaneous or imposed atrial depolarization (and its normal detection), the pacemaker time counter is reset and the AV interval begins. If spontaneous ventricular depolarization occurs in this interval, then ventricular pacing is blocked; otherwise, a ventricular impulse is delivered.

AT. Pacemaker dysfunction and arrhythmias

Binding violation. The stimulation artifact is not followed by a depolarization complex, although the myocardium is not in the refractory stage. Causes: displacement of the stimulating electrode, perforation of the heart, an increase in the stimulation threshold (with myocardial infarction, taking flecainide, hyperkalemia), damage to the electrode or violation of its insulation, disturbances in impulse generation (after defibrillation or due to depletion of the power source), as well as incorrectly set EKS parameters.

Detection violation. The pacer time counter is not reset when self or imposed depolarization of the corresponding chamber occurs, resulting in an abnormal rhythm (imposed rhythm superimposed on own). Reasons: low amplitude of the perceived signal (especially with ventricular extrasystole), incorrectly set pacemaker sensitivity, as well as the reasons listed above (see). It is often enough to reprogram the pacemaker sensitivity.

Hypersensitivity of the pacemaker. At the expected time (after the appropriate interval) no stimulation occurs. T waves (P waves, myopotentials) are misinterpreted as R waves and the pacemaker time counter is reset. In case of erroneous detection of the T wave, the VA interval starts from it. In this case, the sensitivity or refractory period of detection must be reprogrammed. You can also set the VA interval to the T wave.

Blocking by myopotentials. Myopotentials arising from hand movements can be misinterpreted as potentials from the myocardium and block stimulation. In this case, the intervals between the imposed complexes become different, and the rhythm becomes incorrect. Most often, such violations occur when using unipolar pacemakers.

Circular tachycardia. Imposed rhythm with the maximum rate for the pacemaker. Occurs when retrograde atrial stimulation after ventricular pacing is sensed by the atrial lead and triggers ventricular pacing. This is typical for a two-chamber pacemaker with the detection of atrial excitation. In such cases, it may be sufficient to increase the refractory period of detection.

Tachycardia induced by atrial tachycardia. Imposed rhythm with the maximum rate for the pacemaker. It is observed if atrial tachycardia (eg, atrial fibrillation) occurs in patients with a dual-chamber pacemaker. Frequent atrial depolarization is sensed by the pacemaker and triggers ventricular pacing. In such cases, switch to VVI mode and eliminate the arrhythmia.