Electrocardiogram norm. Deciphering the cardiogram of the heart. Identification of the pathology of the conduction of an electrical impulse in the structures of the heart

Pathology of the cardiovascular system is one of the most common problems affecting people of all ages. Timely treatment and diagnosis of the circulatory system can significantly reduce the risk of developing dangerous diseases.

To date, the most effective and easily accessible method of studying the work of the heart is an electrocardiogram.

When examining the results of the examination of the patient, doctors pay attention to such components of the ECG as:

• teeth;
• intervals;
• Segments.

Not only their presence or absence is assessed, but also their height, duration, location, direction and sequence.

There are strict normal parameters for each line on the ECG tape, the slightest deviation from which may indicate violations in the work of the heart.

ECG analysis

The entire set of ECG lines is examined and measured mathematically, after which the doctor can determine some parameters of the work of the heart muscle and its conduction system: heart rate, frequency heart rate, pacemaker, conduction, electrical axis of the heart.

To date, all these indicators are investigated by high-precision electrocardiographs.

Sinus rhythm of the heart

This is a parameter that reflects the rhythm of heart contractions that occur under the influence of the sinus node (normal). It shows the coherence of the work of all parts of the heart, the sequence of processes of tension and relaxation of the heart muscle.

The rhythm is very easy to identify by the tallest R waves: if the distance between them is the same throughout the entire recording or deviates by no more than 10%, then the patient does not suffer from arrhythmia.

heart rate

The number of beats per minute can be determined not only by counting the pulse, but also by the ECG. To do this, you need to know the speed at which the ECG was recorded (usually 25, 50 or 100 mm / s), as well as the distance between the highest teeth (from one peak to another).

By multiplying the recording time of one mm by length of segment R-R you can get your heart rate. Normally, its performance ranges from 60 to 80 beats per minute.

Source of excitation

The autonomic nervous system of the heart is designed in such a way that the process of contraction depends on the accumulation of nerve cells in one of the zones of the heart. Normally, this is the sinus node, the impulses from which diverge throughout nervous system hearts.

In some cases, other nodes (atrial, ventricular, atrioventricular) can take on the role of the pacemaker. This can be determined by examining the P wave is inconspicuous, located just above the isoline.

You can read detailed and comprehensive information about the symptoms of cardiosclerosis of the heart.

Conductivity

This is a criterion showing the process of momentum transfer. Normally, impulses are transmitted sequentially from one pacemaker to another, without changing the order.

Electric axis

An indicator based on the process of excitation of the ventricles. Mathematical analysis of Q, R, S waves in leads I and III allows you to calculate a certain resulting vector of their excitation. This is necessary to establish the functioning of the branches of the His bundle.

The obtained angle of inclination of the axis of the heart is estimated by the value: 50-70° normal, 70-90° deviation to the right, 50-0° deviation to the left.

In cases where there is a tilt of more than 90° or more than -30°, there is a serious malfunction in the bundle of His.

Teeth, segments and intervals

Teeth - ECG sections lying above the isoline, their meaning is as follows:

• P- reflects the processes of contraction and relaxation of the atria.
• Q, S- reflect the processes of excitation of the interventricular septum.
• R- the process of excitation of the ventricles.
• T- the process of relaxation of the ventricles.

Intervals are sections of the ECG lying on the isoline.

• PQ- reflects the propagation time of the impulse from the atria to the ventricles.

Segments - sections of the ECG, including an interval and a wave.

• QRST- the duration of the contraction of the ventricles.
• ST- the time of complete excitation of the ventricles.
• TP is the time of electrical diastole of the heart.

Norm in men and women

Decryption ECG of the heart and the norms of indicators in adults are presented in this table:

Healthy Childhood Outcomes

Deciphering the results ECG measurements in children and their norm in this table:

Dangerous diagnoses

What kind dangerous states can be determined by the ECG readings during decoding?

Extrasystole

This phenomenon characterized by irregular heartbeat. A person feels a temporary increase in the frequency of contractions, followed by a pause. It is associated with the activation of other pacemakers, sending along with the sinus node an additional burst of impulses, which leads to an extraordinary contraction.

If extrasystoles appear no more than 5 times per hour, then they cannot cause significant harm to health.

Arrhythmia

Characterized change in the frequency of sinus rhythm when pulses arrive at different frequencies. Only 30% of these arrhythmias require treatment, because can lead to more serious illnesses.

In other cases, this may be a manifestation of physical activity, a change in hormonal levels, the result of a fever and does not threaten health.

Bradycardia

Occurs when the sinus node is weakened, unable to generate impulses with the proper frequency, as a result of which the heart rate also slows down, up to 30-45 beats per minute.

Tachycardia

The opposite phenomenon, characterized by an increase in heart rate over 90 beats per minute. In some cases, temporary tachycardia occurs under the influence of strong physical exertion and emotional stress, as well as during illnesses associated with fever.

Conduction disorder

In addition to the sinus node, there are other underlying pacemakers of the second and third orders. Normally, they conduct impulses from the first-order pacemaker. But if their functions weaken, a person may feel weakness, dizziness caused by depression of the heart.

It is also possible to lower blood pressure, because. the ventricles will contract less frequently or arrhythmically.

Many factors can lead to disruption in the work of the heart muscle itself. Tumors develop, muscle nutrition is disrupted, and depolarization processes fail. Most of these pathologies require serious treatment.

Why there might be differences in performance

In some cases, when re-analyzing the ECG, deviations from previously obtained results are revealed. With what it can be connected?

• different time of day. Usually, an ECG is recommended to be done in the morning or afternoon, when the body has not yet had time to be influenced by stress factors.
• Loads. It is very important that the patient is calm while recording the ECG. The release of hormones can increase heart rate and distort performance. In addition, before the examination, it is also not recommended to engage in heavy physical labor.
• meal. Digestive processes affect blood circulation, and alcohol, tobacco and caffeine can affect heart rate and pressure.
• electrodes. Improper overlap or accidental shifting can seriously change the performance. Therefore, it is important not to move during the recording and degrease the skin in the area where the electrodes are applied (the use of creams and other skin products before the examination is highly undesirable).
• Background. Sometimes other devices can interfere with the operation of the electrocardiograph.

Additional examination methods

Halter

Method long-term study of the work of the heart, made possible by a portable compact tape recorder that is capable of recording results on magnetic tape. The method is especially good when it is necessary to investigate recurrent pathologies, their frequency and time of occurrence.

Treadmill

Unlike a normal resting ECG, this method based on results analysis after physical activity . It is most commonly used for risk assessment. possible pathologies not detected on a standard ECG, as well as when prescribing a course of rehabilitation to patients who have had a heart attack.

Phonocardiography

Allows analyze heart sounds and murmurs. Their duration, frequency and time of occurrence correlate with the phases of cardiac activity, which makes it possible to assess the functioning of the valves, the risks of developing endocarditis and rheumatic heart disease.

A standard ECG is a graphic representation of the work of all parts of the heart. Its accuracy can be affected by many factors, so doctor's advice should be followed.

The examination reveals most of the pathologies of the cardiovascular system, however, additional tests may be required for an accurate diagnosis.

Finally, we suggest watching a video course on decoding “ECG for everyone”:

Electrocardiogram reflectsonly electrical processesin the myocardium: depolarization (excitation) and repolarization (recovery) of myocardial cells.

Ratio ECG intervals from phases of the cardiac cycle(ventricular systole and diastole).

Normally, depolarization leads to contraction of the muscle cell, and repolarization leads to relaxation.

To simplify further, I will sometimes use “contraction-relaxation” instead of “depolarization-repolarization”, although this is not entirely accurate: there is a concept “ electromechanical dissociation“, in which depolarization and repolarization of the myocardium do not lead to its visible contraction and relaxation.

Elements of a normal ECG

Before moving on to deciphering the ECG, you need to figure out what elements it consists of.

Waves and intervals on the ECG.

It is curious that abroad the P-Q interval is usually calledP-R.

Any ECG consists of teeth, segments and intervals.

TEETH are convexities and concavities on the electrocardiogram.
The following teeth are distinguished on the ECG:

• P(atrial contraction)
• Q, R, S(all 3 teeth characterize the contraction of the ventricles),
• T(ventricular relaxation)
• U(non-permanent tooth, rarely recorded).

SEGMENTS
A segment on an ECG is called straight line segment(isolines) between two adjacent teeth. The P-Q and S-T segments are of the greatest importance. For example, segment P-Q It is formed due to a delay in the conduction of excitation in the atrioventricular (AV-) node.

INTERVALS
The interval consists of tooth (complex of teeth) and segment. Thus, interval = tooth + segment. The most important are the P-Q and Q-T intervals.

Teeth, segments and intervals on the ECG.
Pay attention to large and small cells (about them below).

Waves of the QRS complex

Since the ventricular myocardium is more massive than the atrial myocardium and has not only walls, but also a massive interventricular septum, the spread of excitation in it is characterized by the appearance of a complex complex QRS on the ECG.

How to pick out the teeth?

First of all, evaluate amplitude (dimensions) of individual teeth QRS complex. If the amplitude exceeds 5 mm, the prong denote capital (big) letter Q, R or S; if the amplitude is less than 5 mm, then lowercase (small): q, r or s.

The tooth R (r) is called any positive(upward) wave that is part of the QRS complex. If there are several teeth, subsequent teeth indicate strokes: R, R’, R”, etc.

Negative (downward) wave of the QRS complex, located before the R wave, denoted as Q (q), and after - as S(s). If there are no positive waves at all in the QRS complex, then the ventricular complex is designated as QS.

Variants of the QRS complex.

Fine:

Q wave reflects depolarization of the interventricular septum (excited interventricularforged partition)

R wave - depolarizationthe bulk of the ventricular myocardium ( the apex of the heart and adjacent areas are excited)

S wave - depolarization basal (i.e., near the atria) sections of the interventricular septum ( the base of the heart is excited)

R wave V1, V2 reflects excitation of the interventricular septum,

but R V4, V5, V6 - excitation of the muscles of the left and right ventricles.

necrosis of areas of the myocardium (for example, withmyocardial infarction ) causes widening and deepening of the Q wave, so this wave is always paid close attention.

ECG analysis

General ECG decoding scheme

1. Checking the correctness of ECG registration.
2. Heart rate and conduction analysis:
   • assessment of the regularity of heart contractions,
   • counting the heart rate (HR),
   • determination of the source of excitation,
   • conductivity rating.
3. Determination of the electrical axis of the heart.
4. Analysis of atrial P wave and P-Q interval.
5. Analysis of the ventricular QRST complex:
   • analysis of the QRS complex,
   • analysis of the RS-T segment,
   • T wave analysis,
   • analysis of the interval Q - T.
6. Electrocardiographic conclusion.

Normal electrocardiogram.

1) Checking the correctness of ECG registration

At the beginning of each ECG tape there should be calibration signal- so-called control millivolt. To do this, at the beginning of the recording, a standard voltage of 1 millivolt is applied, which should display on the tape a deviation of 10 mm. Without a calibration signal, the ECG recording is considered invalid.

Normally, in at least one of the standard or augmented limb leads, the amplitude should exceed 5 mm, and in the chest leads - 8 mm. If the amplitude is lower, it is called reduced EKG voltage which occurs in some pathological conditions.

2) Heart rate and conduction analysis:

1. assessment of heart rate regularity

   Rhythm regularity is assessed by R-R intervals. If the teeth are at an equal distance from each other, the rhythm is called regular, or correct. The variation in the duration of individual R-R intervals is allowed no more than ±10% from their average duration. If the rhythm is sinus, it is usually correct.

2. calculation of heart rate (HR)

   Large squares are printed on the ECG film, each of which includes 25 small squares (5 vertical x 5 horizontal).

   For a quick calculation of heart rate with the correct rhythm, the number of large squares between two adjacent R-R teeth is counted.

   At 50 mm/s belt speed: HR = 600 / (number of large squares).
   At 25 mm/s belt speed: HR = 300 / (number of large squares).

   At a speed of 25 mm/s, each small cell is equal to 0.04 s,

   and at a speed of 50 mm / s - 0.02 s.

   This is used to determine the duration of the teeth and intervals.

   With the wrong rhythm usually considered maximum and minimum heart rate according to the duration of the smallest and largest R-R interval, respectively.

3. determination of the source of excitation

   In other words, they are looking for where pacemaker which causes atrial and ventricular contractions.

   Sometimes this is one of the most difficult stages, because various violations excitability and conduction can be very intricately combined, which can lead to misdiagnosis and incorrect treatment.

Sinus rhythm (this is a normal rhythm, and all other rhythms are pathological).
The source of excitation is in sinoatrial node.

ECG signs:

• in standard lead II, the P waves are always positive and are in front of each QRS complex,
• P waves in the same lead have a constant identical shape.

P wave in sinus rhythm.

ATRIAL Rhythm. If the source of excitation is in the lower sections of the atria, then the excitation wave propagates to the atria from the bottom up (retrograde), therefore:

• in leads II and III, P waves are negative,
• There are P waves before each QRS complex.

P wave in atrial rhythm.

Rhythms from the AV junction. If the pacemaker is in the atrioventricular ( atrioventricular node) node, then the ventricles are excited as usual (from top to bottom), and the atria - retrograde (i.e., from bottom to top).

At the same time on the ECG:

• P waves may be absent because they are superimposed on normal QRS complexes,
• P waves may be negative, located after the QRS complex.

Rhythm from the AV junction, P wave overlapping the QRS complex.

Rhythm from the AV junction, the P wave is after the QRS complex.

The heart rate in the rhythm from the AV connection is less than sinus rhythm and is approximately 40-60 beats per minute.

Ventricular, or IDIOVENTRICULAR, rhythm

In this case, the source of rhythm is the conduction system of the ventricles.

Excitation spreads through the ventricles in the wrong way and therefore more slowly. Features of idioventricular rhythm:

• the QRS complexes are dilated and deformed (look “scary”). Normally, the duration of the QRS complex is 0.06-0.10 s, therefore, with this rhythm, the QRS exceeds 0.12 s.
• there is no pattern between QRS complexes and P waves because the AV junction does not release impulses from the ventricles, and the atria can fire from the sinus node as normal.
• Heart rate less than 40 beats per minute.

Idioventricular rhythm. The P wave is not associated with the QRS complex.

d. conductivity assessment.
To correctly account for conductivity, the write speed is taken into account.

To assess conductivity, measure:

• P wave duration (reflects the speed of the impulse through the atria),normally up to 0.1 s.
• interval duration P - Q (reflects the speed of the impulse from the atria to the myocardium of the ventricles); interval P - Q = (wave P) + (segment P - Q). Fine 0.12-0.2s .
• duration of the QRS complex (reflects the spread of excitation through the ventricles). Normally 0.06-0.1 s.
• interval of internal deflection in leads V1 and V6. This is the time between the onset of the QRS complex and the R wave. Normally in V1 up to 0.03 s and in V6 up to 0.05 s. It is mainly used to recognize bundle branch blocks and to determine the source of excitation in the ventricles in the case of ventricular extrasystole(extraordinary contraction of the heart).

Measurement of the interval of internal deviation.

3) Determination of the electrical axis of the heart.

4) Analysis of atrial P wave.

• Normal in leads I, II, aVF, V2 - V6 P wavealways positive.
• In leads III, aVL, V1, the P wave can be positive or biphasic (part of the wave is positive, part is negative).
• In lead aVR, the P wave is always negative.
• Normally, the duration of the P wave does not exceed0.1s, and its amplitude is 1.5 - 2.5 mm.

Pathological deviations of the P wave:

• Pointed high P waves of normal duration in leads II, III, aVF are characteristic of right atrial hypertrophy, for example, with "cor pulmonale".
• A split with 2 peaks, an extended P wave in leads I, aVL, V5, V6 is typical forleft atrial hypertrophysuch as mitral valve disease.

P wave formation (P-pulmonale) with right atrial hypertrophy.

P-wave (P-mitrale) formation in left atrial hypertrophy.

4) P-Q interval analysis:

fine 0.12-0.20s.

An increase in this interval occurs with impaired conduction of impulses through the atrioventricular node ( atrioventricular block, AV block).

AV blockade is 3 degrees:

• I degree - the P-Q interval is increased, but each P wave has its own QRS complex ( no loss of complexes).
• II degree - QRS complexes partially fall out, i.e. Not all P waves have their own QRS complex.
• III degree - complete blockade of in the AV node. The atria and ventricles contract in their own rhythm, independently of each other. Those. an idioventricular rhythm occurs.

5) Analysis of the ventricular QRST complex:

1. analysis of the QRS complex.

   The maximum duration of the ventricular complex is 0.07-0.09 s(up to 0.10 s).

   The duration increases with any blockade of the legs of the bundle of His.

   Normally, the Q wave can be recorded in all standard and augmented limb leads, as well as in V4-V6.

   Q wave amplitude normally does not exceed 1/4 R wave height, and the duration is 0.03 s.

   Lead aVR normally has a deep and wide Q wave and even a QS complex.

   The R wave, like Q, can be recorded in all standard and enhanced limb leads.

   From V1 to V4, the amplitude increases (while the r wave of V1 may be absent), and then decreases in V5 and V6.

   The S wave can be of very different amplitudes, but usually no more than 20 mm.

   The S wave decreases from V1 to V4, and may even be absent in V5-V6.

   In lead V3 (or between V2 - V4) is usually recorded “ transition zone” (equality of the R and S waves).

2. analysis of the RS-T segment

   The ST segment (RS-T) is the segment from the end of the QRS complex to the beginning of the T wave. - - The ST segment is especially carefully analyzed in CAD, as it reflects a lack of oxygen (ischemia) in the myocardium.

   Normally, the S-T segment is located in the limb leads on the isoline ( ± 0.5mm).

   In leads V1-V3, the S-T segment can be shifted upward (no more than 2 mm), and in V4-V6 - downward (no more than 0.5 mm).

   The transition point of the QRS complex to the S-T segment is called the point j(from the word junction - connection).

   The degree of deviation of point j from the isoline is used, for example, to diagnose myocardial ischemia.

3. T wave analysis.

   The T wave reflects the process of repolarization of the ventricular myocardium.

   In most leads where a high R is recorded, the T wave is also positive.

   Normally, the T wave is always positive in I, II, aVF, V2-V6, with T I> T III, and T V6> T V1.

   In aVR, the T wave is always negative.

4. analysis of the interval Q - T.

   The Q-T interval is called electrical ventricular systole, because at this time all departments of the ventricles of the heart are excited.

   Sometimes after the T wave, a small U wave, which is formed due to a short-term increased excitability of the myocardium of the ventricles after their repolarization.

6) Electrocardiographic conclusion.
Should include:

1. Rhythm source (sinus or not).
2. Rhythm regularity (correct or not). Usually sinus rhythm is correct, although respiratory arrhythmia is possible.
3. The position of the electrical axis of the heart.
4. The presence of 4 syndromes:
   • rhythm disorder
   • conduction disorder
   • hypertrophy and/or congestion of the ventricles and atria
   • myocardial damage (ischemia, dystrophy, necrosis, scars)

ECG interference

In connection with FAQ in the comments about the type of ECG I will tell about interference that can be on the electrocardiogram:

Three types of ECG interference(explanation below).

Interference on the ECG in the lexicon of health workers is called tip-off:
a) inductive currents: network pickup in the form of regular oscillations with a frequency of 50 Hz, corresponding to the frequency of the alternating electric current socket.
b) " swimming» (drift) isolines due to poor contact of the electrode with the skin;
c) interference due to muscle trembling(Irregular frequent fluctuations are visible).

ECG analysis algorithm: determination methodology and basic standards

Despite the advent of costly and complex cardiac tests, ECG remains the most reliable method of confirmation. acute infarction, different types arrhythmias, myocardial ischemia. Every health worker needs to be able to decipher an ECG, especially in emergency situations. And can a person far from medicine master the basics of decoding an ECG? Understand how a doctor functional diagnostics interprets ECG results, and the cardiologist establishes the diagnosis on the basis of an electrocardiogram? If you know what the main ECG parameters mean and master the ECG analysis algorithm, then you can learn the basics of ECG decoding even for a person without medical education. Let's try to figure out what is the "life line" on the cardiograph film?

1 The essence of the ECG recording method

The heart works in a certain mode: atrial contraction - ventricular contraction. When the chambers of the heart contract, the cells enter a state of excitation. An action potential is formed between cardiomyocytes due to the appearance of opposite charges between excited cells carrying a “-” charge, and cells with a “+” charge, which are still at rest and have not had time to contract. Such electrical phenomena as the emerging action potential and fixes the electrocardiograph. If it is very simplified to imagine the description of the ECG recording method, then this is a method of recording the work of the heart, namely the excitation of heart cells, the frequency and rhythm of contractions.

2 What is an electrocardiograph?

A device that records electrical impulses from the heart is called an electrocardiograph. It consists of:

• electrodes,
• amplifier,
• recording device.

Electrocardiographs may have mains power, and can be equipped with a battery (for example, portable cardiographs). An ECG is recorded on a paper tape similar to graph paper. The speed of such a tape is usually 50 mm/sec or half as much. So that the doctor does not make a mistake in the calculations, the speed is automatically indicated on the tape itself when recording the ECG.

3 How to take an ECG?

An electrocardiogram is usually recorded in 12 leads: in three standard (I, II, III), three enhanced (aVR, aVL, aVF) from the extremities and in six chest (V1-6). The patient is examined in the supine position with a bare torso and shins free from clothing. Electrodes are applied to the surface of the patient's body in a certain order clockwise: Red - right hand, Yellow - left hand, Green - left leg, Black - right leg.

For the convenience of memorizing electrodes by medical staff, there is a comic phrase, the first letter of each word of which indicates the color of the desired electrode: Rabbit (red) Chews (yellow) Green (green) Garlic (black). 6 chest electrodes are applied to certain areas of the chest.

The contact of the electrodes with the skin should be maximum, so it is necessary to moisten the skin with water or soapy water, degrease with alcohol, sometimes, with dense vegetation in men, it is recommended to shave off the chest hair. After applying the electrodes and connecting the wires, the ECG recording begins. The potential difference is captured by an amplifier, enters the recording device, and then in the form of an ECG graph is displayed on tape. After registering the cardiogram, it is the turn of its analysis.

4 Electrocardiogram basics

Deciphering an ECG is a difficult science, which, perhaps, only a doctor of functional diagnostics is fluent in. All doctors and senior students of medical universities are required to be able to analyze cardiograms and know the ECG parameters well. But the basics, the basics of reading can be learned by people who are far from medicine. So, the ECG consists of such parameters as:

• teeth (p, q, r, s, t, u),
• segments (st, pq),
• intervals (rr, qt, qrs).

Let us dwell on the description of these parameters in more detail. The P wave characterizes the excitation of the atria, from the beginning of the P wave to the next Q wave, the pq segment extends, characterizing the conduction of excitation from the atria to the ventricles along the elements of the conduction system. The Q wave characterizes the beginning of excitation coverage of the interventricular septum and ventricular wall, and the qrs complex characterizes their systole.

The T wave shows the electrical phenomena that occur when the ventricles relax. Pay attention to the pq segment on the ECG. The pq segment characterizes the process of excitation and subsequent relaxation of the ventricular myocardium. The meaning of the U wave is unclear. The rr interval indicates the time between heartbeats, the rr interval is used to judge the heart rate.

5 Important ECG guidelines

From numerous terms and ECG indicators the head is spinning, therefore, when deciphering the ECG, doctors use a certain scheme or algorithm that allows them to conduct a full-fledged analysis of the work of the heart, without forgetting or losing sight of anything. Before analyzing the diagnostic algorithm, it should be noted such ECG indicators as the width or duration of the teeth and intervals (determined vertically) and the amplitude of the teeth and segments (determined horizontally).

If the speed of the paper tape is 25 mm per second, then when determining the width, 1 small cell (1 mm) \u003d 0.04 s., 1 large (5 small) \u003d 0.2 s. Height 10 mm = 1 mV. These data are needed by the doctor for calculations, since a normal ECG is characterized by certain, clearly defined figures for the duration and amplitude of the teeth, intervals and segments, and a pathological ECG is characterized by deviations from normal values. You can present important ECG standards for an adult (speed 25 mm / s) in the form of a table.

If the indicators of certain parameters do not fit into the norm, the doctor of functional diagnostics will write in the conclusion about the alleged violations in the work of the heart.

6 ECG reading algorithm

In general terms, the algorithm for reading all ECG indicators can be presented step by step.

1. 1 STEP. DEFINITION OF THE RHYTHM AND ITS FREQUENCY.
   Normally, the heart rhythm is sinus, which means that the p wave on the ECG always precedes the qrs complex. The heart rate is judged by the duration of the interval rr. There is a formula by which the heart rate is determined: heart rate = 60 / rr. Where rr is the duration of the interval in seconds.
2. 2 STEP. DETERMINATION OF THE ELECTRIC AXIS OF THE HEART.
   The position of the EOS in an adult is usually from 0 to +90 degrees. Vertical EOS (+70-+90) is more common in asthenics, horizontal (0-+30) in stocky patients. But in some diseases, there may be a deviation of the EOS from normal values.
3. 3 STEP. EVALUATION OF INTERVALS, SEGMENTS.
   The doctor carefully studies the duration of intervals, segments, for a more accurate measurement, he can use a ruler. Based on the calculations and by comparing them with normal indicators, the doctor makes a conclusion. For example, an increase in the pr interval of more than 0.2 s. may indicate a pathology such as AV block, and a rise of more than 1 mm in two or more limb leads (II, III, aVF) of the st segment indicates an acute coronary syndrome.
4. 4 STEP. EVALUATION AND ANALYSIS OF TEETH.
   The appearance of a pathological q wave may indicate the development of myocardial infarction. Analyzing a combination of other indicators, the doctor can differentiate a fresh heart attack from a long-standing one. If the p wave is pointed, more than 3 mm in amplitude, this indicates problems with the right atrium, and if the p wave is wide (more than 2.5 mm) and double-humped in II, this indicates an expansion of the left atrium. T changes are not specific. T wave inversion in combination with ST depression or elevation is indicative of ischemia.

7 ECG at rest and not only?

To clarify the diagnosis, hidden heart problems, the doctor may prescribe functional stress tests. Under the influence of physical activity, pressure and heart rate increase, the work of the heart increases and hidden heart problems can “come to the surface”: ischemia, arrhythmias, and other disorders that could not be visualized on the ECG at rest. The most popular stress functional tests include:

• bicycle ergometry (or, as patients like to say, a bicycle. Indeed, the patient pedals a special “bicycle”, while experiencing a certain load, ECG registration occurs in parallel);
• treadmill test (stress test with walking).

It does not hurt to know the basics of an ECG for any patient, but it is still better to entrust the analysis of a cardiogram to a specialist.

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An electrocardiogram is one of the most popular and affordable ways to diagnose heart disease in adults and children. The essence of the ECG method is to mark the electrical impulses that the heart emits, as well as displaying them on recording paper.

Deciphering the results allows you to establish cardiac activity, as well as the structure of the myocardium. It is difficult to decipher the cardiogram on your own, it is for this reason that it is important to contact a specialist cardiologist.

A referral to a cardiogram is issued in such cases:

Disadvantages of an ECG study

Status information is relevant only at the time of verification and may be unreliable. The result is influenced by many factors, which makes the procedure ambiguous. To diagnose more complex diseases, doctors prescribe daily monitoring.

Types of ECG analyzes

An electrocardiograph is used to perform a standard procedure. Such devices are widely used in cardiological hospitals, as well as in ambulances. With the help of suction cups, the electrodes are attached to the human body, and then electrical potentials flow through them.

The electrodes are usually called "leads", in total they are installed 6 pieces. The leads attached to the limbs are considered the main ones and are designated -I, II, III and aVL, aVR, aVF. On the chest, the electrodes are labeled V1-V6.

Each type of lead has a specific task, so individually the factors give different values. The doctor needs to combine all the information into one and decipher the cardiogram.

The graph is displayed on a special graph paper. Each lead has its own schedule. In standard applications, the belt speed is set to 5 cm/s, which can be adjusted if necessary.

Holter monitoring

Unlike the standard procedure, which lasts a few minutes, during Holter monitoring, information is recorded during the day. The duration of the procedure is explained by the need to get a complete picture of the processes occurring in the heart. Such a procedure is able to take readings, not only during a person’s calmness, but also during physical exertion.

Some diseases are difficult to detect during a normal ECG, since abnormalities can only appear during activity.

Other types of procedures

There are also specific procedures for obtaining a cardiogram:

Who appoints the study and when

A sheet with a referral to a cardiogram is issued by the attending physician or cardiologist. If there are complaints or problems with the heart, you should immediately go to the hospital for an examination. This procedure allows you to check the condition of the heart, as well as determine the presence of abnormalities.

With the help of an ECG, a number of specific pathologies can be detected:

• the formation of an expansion in the region of the cardiac chamber;
• changes in the size of the heart muscle;
• development of tissue necrosis in myocardial infarction;
• ischemic lesions of the myocardial wall.

How to prepare for the study

An ECG (decoding in adults implies an exact procedure on the results of which treatment depends) is performed after the doctor explains the main nuances of preparation, to ensure that the results of the study are as accurate as possible:

Modern medicine makes it easy and painless to examine the work of the heart. To do this, in case of malaise or for prevention purposes, a person turns to a cardiologist to receive a referral for analysis.

An ECG is carried out in a specially equipped room in which an electrocardiograph is located. Modern devices are equipped with a thermal printing element that replaces a conventional ink installation. With the help of a thermal effect, an ECG curve appears on paper.

In the latest models of cardiographs, the result is not immediately printed on paper, but remains on the monitor screen. With the help of the program, the device itself decrypts the indicators, and also saves the data on a disk or flash drive.

The device was first developed by Einthoven in 1903. Since then, the cardiograph has received many changes and improvements, but the principle of operation has remained the same. Equipping the device with a multi-channel device allows you to display results from several leads at once.

In 3-channel devices, standard leads are first decoded (I, II, III), then the aVL, aVR, aVF branches coming from the limbs, and at the end of the chest.

room for ECG usually placed away from electromagnetic fields and x-ray exposure. In the treatment room, the patient lies down on a flat couch. Beforehand, you should take off your clothes down to underwear, or open the places for attaching the electrodes.

The electrodes are made in a pear shape on suction cups. Depending on the number of channels in the cardiograph, the color of the wires can be white or multi-colored.

In multichannel devices, marking is performed as follows:

1. V1-red wire;
2. V2-yellow wire;
3. V3-green wire;
4. V4 brown wire;
5. V5 black wire;
6. V6 blue wire.

Before starting the procedure, the doctor should check the quality of the adjacent electrodes to the body. The skin should be clean, without perspiration and oily film. Some of the electrodes are placed at the bottom of the shins and on the feet. For attachment to limbs, suction cups are made in the form of plates. Their purpose is to register standard leads.

Each mount has a specific color to help avoid confusion when examining. The red wire is attached to the right wrist, the yellow wire to the left, to the area where the pulse is actively felt, the green electrode clings to the left limb below, and the black electrode to the right.

When studying the cardiogram, the right leg does not take part in the readings. Therefore, the electrode is connected to it for grounding.

On the cardiogram, a gear diagram with cycles is displayed, which is responsible for the state of the work of the heart muscle on impact and during rest. Such a scheme is called a cardiac cycle, each lead usually has up to 5 cycles. These indications are standard for a conventional ECG, but in case of symptoms of myocardial infarction or other heart disease, these cycles can be several times larger.

After printing the cardiogram, the person is released from the suction cups. The resulting paper is signed and left for analysis. In specific cases, the cardiogram is prescribed after exercise. To obtain correct results, readings are taken before and after exercise.

Norms of ECG indicators

An ECG (decoding in adults includes a number of indicators with an acceptable interval) is carried out according to the values ​​\u200b\u200bthat indicate a healthy state of the cardiac system.

Contraindications

In most cases, the procedure is carried out for everyone, including young children. It is necessary to abandon the ECG only in case of a violation of the skin condition at the places where the electrodes are attached. It should be remembered that in case of emergency hospitalization, the cardiogram is removed in any case.

What can affect the result of the ECG

The reliability of the data obtained is influenced by the following indicators:

Before lying on the treatment table, a person should spend 10-15 minutes in a calm environment. It is important that the person does not worry and his pulse is within the established limits.

Deciphering the results

ECG (decoding in adults takes place, taking into account three indicators: the interval of contractions, segmental factors and the size of the teeth) indicates the risk of developing arrhythmia.

Sinus rhythm of the heart

This factor is responsible for the systematic movement of both atria, which are active under the influence of sinus action. With its help, you can study how well the parts of the heart function, displays the correct work of tension and relaxation of the heart muscle.

The highest teeth on the diagram are responsible for the state of the rhythm. Normally, the gap between the peaks should be standard or vary by no more than 10%. Otherwise, an arrhythmia will occur.

heart rate

The heart rate in a simple sense is referred to as the pulse, it is easily considered in the study of the ECG. To do this, take the speed of the cardiogram, as well as the size of the segment between the high peaks.

Typically, the process speed is 25, 50 and 100 mm/s. The frequency is determined by multiplying the duration of the recording by the length of the segment.

Conductivity

This factor indicates the state of the impulse transmission. In the normal state, the pulses are transmitted in the same sequence.

The teeth in the ECG sections are deciphered as follows:

What heart diseases can be detected using an ECG

ECG (decoding in adults may indicate a number of pathologies) indicates dangerous diseases requiring urgent intervention.

What to do if deviations from the norm are found

The first received cardiogram does not always reflect the true picture of the patient's heart condition. That is why after receiving the results, it is recommended to undergo a second test. Some heart diseases are not detected during a routine examination and require more accurate tests.

After receiving bad results some subtleties should be reconsidered:

1. Time of day when the ECG was performed. According to the rules, the procedure is carried out in the morning, on an empty stomach.
2. Emotional condition. If a person is stressed or worried, the doctor should know about it so that the ECG results do not change for the worse.
3. It should be remembered whether there was a meal before the first ECG. This harmless factor can greatly affect the readings, especially if the patient has consumed alcohol, fatty foods or coffee.
4. In some cases, electrodes may come off during the procedure, which drastically affects decoding.

Heart rhythm problems may be present in life healthy people, which is the norm. Therefore, when receiving negative results, you should not immediately despair, since the heart is a sensitive organ and its study takes a lot of time.

Considering these factors, the procedure followed should be reviewed. In any case, if there are complaints or symptoms, the patient is sent for a second ECG. Deciphering ECG readings in adults is a complex and painstaking task. The specialist is required to have a correct understanding of all angles and components. Keep in mind that readings and results can be affected by different values.

Article formatting: Mila Fridan

Video about decoding the ECG

How to decode an ECG correctly:

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 mobile team has a portable and lightweight electrocardiograph capable of reading information by fixing the electrical impulses of the heart muscle - myocardium at the moment of contraction on the recorder.

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.

ECG of the heart for diabetics who, in addition to diabetes there are also late cardiovascular complications, which makes 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, thromboembolism pulmonary artery 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 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 capture 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. 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 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 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 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, 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 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 back wall 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.

Sinus rhythm, irregular P-P 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.

Most bright sign 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 periodically occurring 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 the appointment of this type of analysis are painless symptoms 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 are 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, you should 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 must get into his everyday 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.

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