Small R-wave growth is a common ECG symptom that is often misinterpreted by doctors. Although this symptom is usually associated with anterior myocardial infarction, it can also be caused by other non-infarction conditions.

A small increase in the R wave is detected approximately in 10% of hospitalized adult patients and is the sixth most common ECG abnormality (19,734 ECGs were collected by Metropolitan Life Insurance Company over a 5 ¼ year period). Moreover, one third of patients with previous anterior myocardial infarction may only have this symptom on the ECG. Thus, the elucidation of specific anatomical equivalents of this electrocardiographic phenomenon is of great clinical importance.

Normal distribution of R-waves in the chest leads.

Normal R wave height in lead V3 is usually more than 2 mm ... If the height of the R waves in leads V1-V4 is extremely small, it is said that there is "insufficient, or small increase in the R wave".
There are various definitions of low R-wave gain in the literature, criteria such asR waves less than 2-4 mm in leads V3 or V4and / or the presence of a reverse growth of the R wave (RV4< RV3 или RV3 < RV2 или RV2 < RV1 или любая их комбинация).

In myocardial necrosis due to infarction, a certain amount of myocardial tissue becomes electrically inert and unable to generate normal depolarization. Depolarization of the surrounding tissues of the ventricles at this time increases (since there is no longer resistance to them), and the resulting depolarization vector is reoriented in the direction away from the necrosis zone (in the direction of unhindered propagation). With anterior myocardial infarction, Q waves appear in the right and middle leads (V1-V4). However, in a significant number of patients, Q waves are not preserved.

In documented cases of previous anterior myocardial infarction, a small increase in the R wave is detected in 20-30% of cases . The average time for the complete disappearance of pathological Q waves is 1.5 years.

Noteworthy decrease in the amplitude of the R wave in lead I ... Up to 85% of patients with anterior myocardial infarction and low R-wave growth have either the amplitude of the R waves in lead I<= 4 мм or R-wave amplitude in lead V3<= 1,5 мм ... The absence of these amplitude criteria makes the diagnosis of anterior myocardial infarction unlikely (except for 10% -15% of cases of anterior myocardial infarction).

In the presence of a small increase in the R waves in the chest leads, violation of repolarization (ST-T changes) in leads V1-V3 will increase the likelihood of diagnosing old anterior myocardial infarction.

Other possible causes of insufficient R-wave growth in the chest leads are:

• complete / incomplete left bundle branch block,
• blockade of the anterior branch of the left bundle branch,
• Wolff-Parkinson-White phenomenon,
• some types of right ventricular hypertrophy (especially those associated with COPD),
• left ventricular hypertrophy
• right ventricular hypertrophy type C.

Acute anterior MI

Another common reason for a small increase in the R wave is improper placement of the electrodes: too high or too low location of the chest electrodes, the location of the electrodes from the limbs on the trunk.

Most often, the high position of the right chest electrodes leads to insufficient growth of the R waves. When the electrodes are moved to the normal position, the normal growth of the R waves is restored, however with old anterior myocardial infarction, QS complexes will persist .

A relationship was found between a small increase in the R wave on the ECG and diastolic dysfunction in patients with diabetes mellitus; therefore, this symptom may be an early sign of LV dysfunction and DCM in diabetics.

References.

1. Electrocardiographic Poor R-Wave Progression. Correlation with Postmortem Findings. Michael I. Zema, M.D., Margaret Collins, M.D .; Daniel R. Alonso, M. D .; Paul Kligfield, M.D. CHEST, 79: 2, FEBRUARY, 1981
2. Diagnostic value of poor R-wave progression in electrocardiograms for diabetic cardiomyopathy in type 2 diabetic patients / CLINICAL CARDIOLOGY, 33 (9): 559-64 (2010)
3. Poor R Wave Progression in the Precordial Leads: Clinical Implications for the Diagnosis of Myocardial Infarction NICHOLAS L. DePACE, MD, JAY COLBY, BS, A-HAMID HAKKI, MD, FACC, BRUNOMANNO, MD, LEONARD N. HOROWITZ, MD, FACC , ABDULMASSIH S. ISKANDRIAN, MD, FACC. JACC Vol. 2.No. 6 December 1983 "1073- 9
4. Poor R-Wave Progression. J Insur Med 2005; 37: 58-62. Ross MacKenzie, MD
5. Dr. Smith "s ECG Blog. Monday, June 6, 2011
6. Dr. Smith "s ECG Blog. Tuesday, July 5, 2011
7. http://www.learntheart.com/ Poor R Wave Progression (PRWP) ECG
8. http://clinicalparamedic.wordpress.com/ R-Wave Progression: Is it important? YOU BET !!

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R wave(the main wave of the ECG) is caused by excitation of the ventricles of the heart (for more details, see "Excitation in the myocardium"). The amplitude of the R wave in standard and reinforced leads depends on the location of the electrical axis of the heart (EOS). With a normal arrangement of the e.o. R II> R I> R III.

• The R wave may be absent in enhanced lead aVR;
• With a vertical arrangement of the e.o. R wave may be absent in lead aVL (on the ECG on the right);
• Normally, the amplitude of the R wave in lead aVF is greater than in standard lead III;
• In the chest leads V1-V4, the amplitude of the R wave should increase: R V4> R V3> R V2> R V1;
• Normally, in lead V1, the r wave may be absent;
• In young people, the R wave may be absent in leads V1, V2 (in children: V1, V2, V3). However, such an ECG is often a sign of myocardial infarction of the anterior interventricular septum of the heart.

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Records impulses, and converts them into a visual graph on paper (electrocardiogram) a special device - an electrocardiograph.

Brief description of ECG elements

The time is recorded horizontally on the graphic image, and the frequency and depth of changes are recorded vertically. Sharp angles displayed above (positive) and below (negative) from the horizontal line are called prongs. Each of them is an indicator of the state of one or another part of the heart.

On the cardiogram, the teeth are designated as P, Q, R, S, T, U.

• the T wave on the ECG displays the recovery phase of the muscle tissue of the heart ventricles between myocardial contractions;
• P wave - an indicator of depolarization (excitation) of the atria;
• teeth Q, R, S reflect the excited state of the ventricles of the heart;
• The U-wave determines the recovery cycle of the distant portions of the heart ventricles.

The range between adjacent teeth is called a segment, there are three of them: ST, QRST, TP. The barb and segment together represent the interval - the pulse travel time. For accurate diagnostics, the difference in the indicators of the electrodes (electrical potential of the lead) attached to the patient's body is analyzed. Leads are divided into the following groups:

• standard. I - the difference in indicators on the left and right hand, II - the ratio of potentials on the right hand and left leg, III - left hand and leg;
• reinforced. AVR - from the right hand, AVL - from the left hand, AVF - from the left leg;
• chest. Six leads (V1, V2, V3, V4, V5, V6) located on the patient's chest, between the ribs.

A qualified cardiologist is involved in decoding the research result.

Having received a schematic picture of the work of the heart, the cardiologist analyzes the change in all indicators, as well as the time for which the cardiogram marks them. The main data for deciphering are the regularity of the muscle contractions of the heart, the number (number) of heart contractions, the width and shape of the teeth reflecting the excited state of the heart (Q, R, S), the characteristic of the P-wave, the parameters of the T wave and segments.

T wave indicators

Repolarization or restoration of muscle tissue after contractions, which reflects the T wave, in the graphic image has the following standards:

• lack of serration;
• smoothness on the rise;
• upward direction (positive value) in leads I, II, V4 – V6;
• strengthening the range values ​​from the first to the third assignment up to 6-8 cells along the graphical axis;
• downward directivity (negative value) in AVR;
• duration from 0.16 to 0.24 seconds;
• predominance in height in the first lead in relation to the third, as well as in lead V6 compared to lead V1.

T wave changes

The transformation of the T wave on the electrocardiogram is due to changes in the work of the heart. Most often they are associated with a violation of the blood supply, which has arisen due to vascular lesions by atherosclerotic growths, otherwise, ischemic heart disease.

Deviation from the norm of lines reflecting inflammatory processes can vary in height and width. The main deviations are characterized by the following configurations.

The inverted (inverse) form indicates myocardial ischemia, a state of extreme nervous excitement, cerebral hemorrhage, an increase in the frequency of heart contractions from above (tachycardia). Equalized T is manifested in alcoholism, diabetes, low potassium concentration (hypokalemia), cardiac neurosis (neurocircular dystonia), and antidepressant abuse.

A high T-wave, displayed in the third, fourth and fifth leads, is associated with an increase in the volume of the walls of the left ventricle (left ventricular hypertrophy), pathologies of the autonomic nervous system. A slight rise in the pattern does not pose a serious danger, most often, it is associated with irrational physical exertion. Biphasic T is indicative of overuse of cardiac glycosides or left ventricular hypertrophy.

The tooth displayed at the bottom (negative) is an indicator of the development of ischemia or the presence of strong excitement. If at the same time there is a change in the ST segment, a clinical form of ischemia - a heart attack - should be suspected. Changes in the tooth pattern without involvement of the adjacent ST segment are not specific. It is extremely difficult to determine a specific disease in this case.

Etiological factors of T wave changes in cardiac muscle pathology a significant amount

Causes of a negative T wave

If, with a negative value of the T wave, additional factors are involved in the process, this is an independent heart disease. When there are no concomitant manifestations on the ECG, a negative T display may be due to the following factors:

• pulmonary pathology (shortness of breath);
• malfunctions of the hormonal system (hormone levels above or below normal);
• violation of cerebral circulation;
• overdose of antidepressants, heart medications, and medications;
• symptomatic complex of disorders of a part of the nervous system (VVD);
• dysfunction of the heart muscle, not associated with ischemic disease (cardiomyopathy);
• inflammation of the bursa (pericarditis);
• inflammatory process in the inner lining of the heart (endocarditis);
• mitral valve lesions;
• expansion of the right heart as a result of hypertension (cor pulmonale).

Objective ECG data regarding changes in the T wave can be obtained by comparing the cardiogram taken at rest and the ECG in dynamics, as well as the results of laboratory studies.

Since abnormal T-wave imaging can indicate coronary artery disease (ischemia), regular electrocardiography should not be neglected. Regular visits to a cardiologist and an ECG procedure will help identify pathology at the initial stage, which will greatly simplify the treatment process.

ECG interpretation: s wave

The s wave (inconsistent wave) is caused by the final excitation of the base of the left ventricle of the heart (for more details, see "Excitation in the myocardium").

• In the chest leads, the greatest amplitude of the S wave is observed in lead V1 or V2;
• The amplitude of the S wave gradually decreases from leads V1, V2 to leads V5, V6, where it may be absent altogether;
• With the transition from the right chest leads to the left, there is an increase in the R wave and a decrease in the S wave;
• A lead in which the amplitudes of the R and S waves are the same is called the transition zone (usually V3, less often V4);
• Usually, in the right chest leads (V1, V2), the ECG normally looks like rS (small positive wave, and large negative);
• In the left chest leads (V5, V6), the ECG normally looks like qRS or qR - with a pronounced positive R wave.

What state of the myocardium reflects the R wave on the ECG results?

The state of the whole organism depends on the health of the cardiovascular system. When unpleasant symptoms occur, most people seek medical attention. Having received the results of an electrocardiogram on their hands, few people understand what is at stake. What does the p wave reflect on the ECG? What alarming symptoms require medical supervision and even treatment?

Why is an electrocardiogram performed?

After the examination by the cardiologist, the examination begins precisely with the electrocardiography. This procedure is very informative, despite the fact that it is carried out quickly, does not require special training and additional costs.

The cardiograph records the passage of electrical impulses through the heart, records the heart rate and can detect the development of serious pathologies. The teeth on the ECG give a detailed idea of ​​the different parts of the myocardium and how they work.

The norm for an ECG is that different teeth differ in different leads. They are calculated by determining the value relative to the projection of the EMF vectors on the lead axis. The prong can be positive and negative. If it is located above the isoline of cardiography, it is considered positive, if below it, it is negative. A biphasic tooth is recorded when, at the moment of excitation, the tooth passes from one phase to another.

Important! An electrocardiogram of the heart shows the state of the conductive system, which consists of bundles of fibers through which impulses pass. Observing the rhythm of contractions and the characteristics of rhythm disturbances, you can see various pathologies.

The conducting system of the heart is a complex structure. It consists of:

• sinoatrial node;
• atrioventricular;
• legs of the bundle of His;
• Purkinje fibers.

The sinus node, as a pacemaker, is the source of impulses. They are formed at a rate of once a minute. With various disorders and arrhythmias, impulses can be generated more often or less often than normal.

Sometimes bradycardia (slow heartbeat) develops due to the fact that the function of the pacemaker is taken over by another part of the heart. Arrhythmic manifestations can also be caused by blockages in various zones. Because of this, the automatic control of the heart is impaired.

What the ECG shows

If you know the norms for cardiogram indicators, how the teeth should be located in a healthy person, you can diagnose many pathologies. This examination is carried out in an inpatient setting, on an outpatient basis and in emergency critical cases by ambulance doctors to make a preliminary diagnosis.

Changes reflected in the cardiogram may indicate the following conditions:

• rhythm and heart rate;
• myocardial infarction;
• blockade of the cardiac conduction system;
• violation of the metabolism of important trace elements;
• blockage of large arteries.

Obviously, an electrocardiogram study can be very informative. But what are the results of the data obtained?

Attention! In addition to the teeth, there are segments and intervals in the ECG picture. Knowing what is the norm for all these elements, you can make a diagnosis.

Detailing the decoding of the electrocardiogram

The norm for the P wave is the location above the isoline. This atrial tooth can be negative only in leads 3, aVL and 5. In leads 1 and 2 it reaches its maximum amplitude. The absence of a P wave may indicate a serious disturbance in impulse conduction in the right and left atrium. This tooth reflects the state of this particular part of the heart.

The P wave is deciphered first, since it is in it that an electrical impulse originates, transmitted to the rest of the heart.

Cleavage of the P wave, when two apices are formed, indicates an enlargement of the left atrium. Bifurcation often develops with pathologies of the bicuspid valve. The double-humped P wave becomes an indication for additional cardiac examinations.

The PQ interval shows how the impulse is transferred to the ventricles through the atrioventricular node. The norm for this section is a horizontal line, since there are no delays due to good conductivity.

The Q wave is normally narrow, its width is no more than 0.04 s. in all leads, and the amplitude is less than a quarter of the R wave. If the Q wave is too deep, this is one of the possible signs of a heart attack, but the indicator itself is assessed only in combination with others.

The R wave is ventricular, so it is the highest. The walls of the organ in this zone are the most dense. As a result, the electric wave travels the longest. Sometimes it is preceded by a small negative Q wave.

During normal heart function, the highest R wave is recorded in the left chest leads (V5 and 6). Moreover, it should not exceed 2.6 mV. Too high a tooth is a sign of left ventricular hypertrophy. This condition requires in-depth diagnostics to determine the reasons for the increase (coronary artery disease, arterial hypertension, valvular heart disease, cardiomyopathy). If the R wave falls sharply from V5 to V6, this could be a sign of MI.

After this reduction, the recovery phase begins. On the ECG, this is illustrated as the formation of a negative S wave. After a small T wave, a ST segment follows, which should normally be represented by a straight line. The Tckb line remains straight, there are no bent areas on it, the condition is considered normal and indicates that the myocardium is completely ready for the next RR cycle - from contraction to contraction.

Determination of the axis of the heart

Another step in decoding the electrocardiogram is to determine the axis of the heart. A normal tilt is between 30 and 69 degrees. Smaller indicators indicate a deviation to the left, and large ones - to the right.

Possible research errors

It is possible to obtain inaccurate data from the electrocardiogram if, when registering signals, the cardiograph is affected by the following factors:

• fluctuations in the frequency of alternating current;
• displacement of the electrodes due to their loose overlap;
• muscle tremors in the patient's body.

All these points affect obtaining reliable data during electrocardiography. If the ECG shows that these factors have taken place, the study is repeated.

When a cardiogram is decoded by an experienced cardiologist, you can get a lot of valuable information. In order not to start the pathology, it is important to consult a doctor at the first painful symptoms. So you can preserve health and life!

S wave reflects on ecg

The electrocardiogram reflects only electrical processes in the myocardium: depolarization (excitation) and repolarization (restoration) of myocardial cells.

The ratio of ECG intervals with the phases of the cardiac cycle (systole and diastole of the ventricles).

Normally, depolarization leads to muscle cell contraction, and repolarization leads to relaxation. To simplify further, instead of “depolarization-repolarization”, I will sometimes use “contraction-relaxation”, although this is not entirely accurate: there is the concept of “electromechanical dissociation”, in which depolarization and repolarization of the myocardium does not lead to its visible contraction and relaxation. I wrote a little more about this phenomenon. before.

Elements of a normal ECG

Before proceeding to decoding the ECG, you need to figure out what elements it consists of.

ECG waves and intervals. It is curious that abroad the P-Q interval is usually called P-R.

Any ECG consists of waves, segments and intervals.

Teeth are the bulges and concavities on an 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 (inconsistent wave, rarely recorded).

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

INTERVALS An interval consists of a wave (complex of teeth) and a segment. So spacing = prong + segment. The most important are the P-Q and Q-T intervals.

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

The teeth 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 QRS complex on the ECG. How to select the teeth in it correctly?

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

The R (r) wave is any positive (upward) wave that is part of the QRS complex. If there are several teeth, the subsequent teeth are designated by strokes: R, R ', R ", etc. The negative (downward) tooth of the QRS complex, located in front of the R wave, is designated as Q (q), after - as S (s). If there are no positive teeth in the QRS complex at all, then the ventricular complex is designated as QS.

Variants of the QRS complex.

Normally, the Q wave reflects the depolarization of the interventricular septum, the R wave - the bulk of the ventricular myocardium, the S wave - the basal (i.e. near the atria) sections of the interventricular septum. The R V1, V2 prong reflects the excitation of the interventricular septum, and R V4, V5, V6 - the excitation of the muscles of the left and right ventricles. Death of areas of the myocardium (for example, with myocardial infarction) causes the expansion and deepening of the Q wave, therefore, this wave is always paid close attention to.

General ECG decoding scheme

Checking the correctness of the ECG registration.

Heart rate and conduction analysis:

assessment of the regularity of heart contractions,

counting heart rate (HR),

determination of the source of excitation,

Determination of the electrical axis of the heart.

Analysis of the atrial P wave and the P - Q interval.

Ventricular QRST Analysis:

analysis of the QRS complex,

analysis of the RS - T segment,

analysis of the Q - T interval.

1) Checking the correctness of ECG registration

At the beginning of each ECG tape, there must be a calibration signal - the so-called reference millivolt. To do this, at the beginning of the recording, a standard voltage of 1 millivolt is applied, which should display a deviation of 10 mm on the tape. Without a calibration signal, the ECG recording is considered incorrect. Normally, in at least one of the standard or reinforced limb leads, the amplitude should exceed 5 mm, and in the chest leads - 8 mm. If the amplitude is lower, this is called a reduced ECG voltage, which occurs in some pathological conditions.

Control millivolt on the ECG (at the beginning of the recording).

2) Analysis of heart rate and conduction:

assessment of the regularity of heart contractions

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

counting heart rate (HR)

Large squares are printed on the ECG film, each of which includes 25 small squares (5 vertically x 5 horizontally). To quickly calculate the heart rate at the correct rhythm, count the number of large squares between two adjacent R-R waves.

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

On the overlying ECG, the R-R interval is approximately 4.8 large cells, which at a speed of 25 mm / s gives 300 / 4.8 = 62.5 bpm

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 length of the waves and intervals.

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

determination of the source of excitation

In other words, they look for where the pacemaker is located, which causes contractions of the atria and ventricles. Sometimes this is one of the most difficult stages, because various disturbances of excitability and conduction can be very confusingly combined, which can lead to misdiagnosis and wrong treatment. To correctly determine the source of excitation on the ECG, you need to know well cardiac conduction system.

SINUS rhythm (this is a normal rhythm and all other rhythms are abnormal). The source of excitation is located in the sinus-atrial node. ECG signs:

in standard lead II, the P waves are always positive and are located in front of each QRS complex,

P waves in the same lead are consistently the same shape.

P wave in sinus rhythm.

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

in II and III leads P waves are negative,

P waves are in front of each QRS complex.

P wave at atrial rhythm.

Rhythms from the AV connection. 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). In this case, on the ECG:

P waves may be missing because they overlap with normal QRS complexes,

P waves can be negative, located after the QRS complex.

Rhythm from AV junction, P wave superposition on QRS complex.

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

The heart rate at the rhythm from the AV connection is less than the sinus rhythm and is equal to approximately beats per minute.

Ventricular, or IDIOVENTRICULAR, rhythm (from the Latin. Ventriculus [ventriculus] - ventricle). In this case, the source of the rhythm is the ventricular conduction system. Excitation spreads through the ventricles in the wrong ways and therefore more slowly. Features of idioventricular rhythm:

QRS complexes are widened 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 the QRS complexes and the P waves, because the AV junction does not emit impulses from the ventricles, and the atria can be excited from the sinus node, as in normal conditions.

Heart rate less than 40 beats per minute.

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

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

To assess conductivity, measure:

the duration of the P wave (reflects the speed of the impulse through the atria), normally up to 0.1 s.

the duration of the P - Q interval (reflects the speed of the impulse from the atria to the ventricular myocardium); P - Q interval = (P wave) + (P - Q segment). Normal 0.12-0.2 s.

the duration of the QRS complex (reflects the spread of excitation through the ventricles). Normally 0.06-0.1 s.

the interval of internal deviation 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 case of ventricular premature beats(extraordinary contraction of the heart).

Measuring the interval of internal deviation.

3) Determination of the electrical axis of the heart. In the first part of the cycle about the ECG, it was explained what is electrical axis of the heart and how it is defined in the frontal plane.

4) Analysis of the atrial P wave. Normally, in leads I, II, aVF, V2 - V6, the P wave is always 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 exceed 0.1 s, 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 apex, an expanded P wave in leads I, aVL, V5, V6 is characteristic of left atrial hypertrophy, for example, with mitral valve defects.

Formation of the P wave (P-pulmonale) with right atrial hypertrophy.

Formation of the P wave (P-mitrale) with left atrial hypertrophy.

P-Q interval: normal 0.12-0.20 s. An increase in this interval occurs with impaired conduction of impulses through the atrioventricular node (atrioventricular block, AV block).

AV block is of 3 degrees:

I degree - the P-Q interval is increased, but each P wave has its own QRS complex (there is 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 conduction in the AV node. The atria and ventricles contract in their own rhythm, independently of each other. Those. there is an idioventricular rhythm.

5) Analysis of the ventricular QRST complex:

analysis of the QRS complex.

The maximum duration of the ventricular complex is 0.07-0.09 s (up to 0.10 s). Duration increases with any bundle branch block.

Normally, the Q wave can be recorded in all standard and enhanced limb leads, as well as in V4-V6. The amplitude of the Q wave does not normally exceed 1/4 of the height of the R wave, and the duration is 0.03 s. In lead aVR, there is normally a deep and wide Q wave and even a QS complex.

The R wave, like the Q wave, 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 in V5-V6 it may even be absent. In lead V3 (or between V2 - V4), a "transition zone" (equality of the R and S waves) is usually recorded.

RS segment analysis - T

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

Normally, the S-T segment is located in the leads from the limbs on the isoline (± 0.5 mm). In leads V1-V3, the S-T segment may be displaced upward (no more than 2 mm), and in V4-V6 - downward (no more than 0.5 mm).

The transition point of the QRS complex into the S-T segment is called 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.

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.

analysis of the Q - T interval.

The Q-T interval is called the electrical ventricular systole, because at this time all parts of the ventricles of the heart are excited. Sometimes after the T wave, a small U wave is recorded, which is formed due to a short-term increased excitability of the ventricular myocardium after their repolarization.

6) Electrocardiographic conclusion. Should include:

The source of the rhythm (sinus or not).

Regularity of rhythm (correct or not). Sinus rhythm is usually correct, although respiratory arrhythmias are possible.

The position of the electrical axis of the heart.

The presence of 4 syndromes:

hypertrophy and / or overload of the ventricles and atria

myocardial damage (ischemia, degeneration, necrosis, scars)

Examples of conclusions (not entirely complete, but real):

Sinus rhythm with heart rate 65. Normal position of the electrical axis of the heart. No pathology was revealed.

Sinus tachycardia with a heart rate of 100. A single supragastric extrasystole.

Sinus rhythm with a heart rate of 70 bpm. Incomplete right bundle branch block. Moderate metabolic changes in the myocardium.

Examples of ECGs for specific diseases of the cardiovascular system - next time.

In connection with frequent questions in the comments about the type of ECG, I will tell you about the interference that may be on the electrocardiogram:

Three types of ECG disturbances (explained below).

Interference on the ECG in the vocabulary of health workers is called pickup: a) inrush currents: network pickup in the form of regular oscillations with a frequency of 50 Hz, corresponding to the frequency of an alternating electric current in the outlet. b) "swimming" (drift) of the isoline due to poor contact of the electrode with the skin;

S wave reflects on ecg

The S wave is directed downward from the isoline and follows the R wave. In the standard and left chest leads, it reflects the depolarization of the basal sections of the wall of the left and right ventricles and the interventricular septum. The depth of the S wave in different leads varies from 0 to 20 mm. The depth of the SI, II, III wave is due to the position of the heart in the chest - the more the heart is turned to the right (located vertically), the deeper the S wave in standard lead I, and, conversely, the more the heart is turned to the left (horizontal position), the deeper the tooth S in lead III. In the right chest leads, the S wave is quite deep. It decreases from right to left (from V1, 2 to V6).

The QRS complex is the initial part of the ventricular complex (QRS-T). The width of the QRS complex normally ranges from 0.06 to 0.1 s. Its increase reflects a slowdown in intraventricular conduction. The shape of the QRS complex can be altered as a result of serration in the ascending or descending knee. The jaggedness of the QRS complex may reflect the pathology of intraventricular conduction, provided that the QRS is broadened, which is observed with ventricular hypertrophy, blockade of the branches of the atrioventricular bundle.

The nature of the teeth of the QRS complex naturally changes in the chest leads. In lead V1, the r wave is small or completely absent. The QRSv complex has the form rS or QS. The rv2 tooth is slightly higher than rV1. The QRS v2 complex also has the rS or RS form. In lead V3, the R wave is higher than the R wave of Vj. R wave above the Rv3 wave. Normally, an increase in the R wave from right to left from Rv1 to RV4 is natural. The Ry wave, the largest in the chest leads.

The RV5 wave is slightly smaller than the Rv4 wave (sometimes equal to or slightly higher than R v5), and the R v6 wave is lower than RV3. An isolated decrease in the R wave in one or more middle chest leads (V3, V4) always indicates pathology. The Sv1 tooth is deep, of greater amplitude than the SV2 tooth, which is larger than SV6, the latter, in turn, is larger than SV4> SV5> SVs. Consequently, the amplitude of the S wave gradually decreases from right to left. Often, there is no S wave in leads V5,6.

The same size of the R and S waves in the chest leads defines the "transition zone". The location of the transition zone is of great importance for the detection of electrocardiographic pathology. Normally, the "transition zone" is defined in leads V3, less often in V2 or V4. It can be at points between V2 and Uz or between V3 and V4. When the heart is turned counterclockwise around the longitudinal axis of the heart, the "transition zone" is displaced to the right.

Such positional changes are more often observed with left ventricular hypertrophy - in lead V2 the R wave is high (Rv2> Sv2) and occasionally there may be a small qVa wave (qRSvJ. According to M.I. in the chest leads is of much greater importance in determining electrocardiographic pathology than changes in the absolute dimensions of the amplitude of the teeth, since the latter depends not only on the state of the myocardium, but also on a number of extracartial factors (on the width of the chest, the height of the diaphragm, the severity of pulmonary emphysema, etc.). ).

The height of the R wave and the depth of the Q and S waves in the limb leads are more dependent on the position of the electrical axis of the heart. With its normal position in leads I, II, III and aVF, the R wave is larger than the S wave. The dimensions and ratio of the R wave and S wave in leads I, II and III in healthy individuals change depending on the position of the electrical axis of the heart.

Educational video of the assessment of the QRS complex on the ECG in health and disease

Determination of the electrical axis of the heart. Normal ECG with normal heart position

Einthoven proposed to determine the angle between the horizontal line (parallel to the lead I axis), drawn through the center of the triangle, and the electric axis - the angle a to describe the location of Aqrs in the frontal plane. He marked the left end of the horizontal line (the positive pole of the I axis of assignment) 00, the right end ± 180 °. The lower end of the perpendicular intersecting the horizontal line in the center, it denoted + 90 °, the upper -90 °. Now with a simple protractor, laid along the horizontal axis, you can determine the angle a. In our example, the angle is a = + 40 °.

The same method can be used to determine the position of the electrical axis (mean vector) of ventricular repolarization (AT) - angle a. and the electrical axis of excitation of the atria (Ap) is the angle a in the frontal plane.

The position of the electrical axis can be determined using the Dyed scheme. Pre-calculate the algebraic sum of the amplitude of the teeth of I and III leads in millimeters. The resulting values ​​are then deposited on the corresponding sides of the circuit. The intersections of the grid with the radial lines indicate the magnitude of the angle a.

For this purpose, the tables of R. Ya. Pismenny and others are also used.

It is generally accepted to consider the normal position of the electric axis in the segment from + 30 ° to + 69 °. The location of the electric axis in the segment from 0 ° to + 29 ° is considered horizontal. If the electrical axis is located to the left of 0 ° (in the -1 ° -90 ° quadrant), they speak of its deviation to the left. The location of the electric axis in the segment from + 70 ° to + 90 ° is considered vertical. They talk about the deviation of the electrical axis to the right when it is located to the right of + 90 ° (in the right half of the coordinate system).

A normal ECG reflects the correct sequence of excitation of the heart, the normal orientation of the EMF vectors of their excitation, which is characteristic of the sinus rhythm, and therefore the standard relationship between the direction and amplitude of the teeth in different leads. as well as the normal duration of intervals between cycles and within cycles.

The figure shows the ECG of a healthy woman G. 32 years old. The sinus rhythm is correct, the heart rate is 62 in 1 min. (R - R = 0.95 sec.). P - Q = 0.13 sec. P = 0.10 sec. QRS = 0.07 sec. Q - T = 0.38ex. RII> R> RIII. In the frontal plane, the location of the AQRS = + 52 °. AT = + 39 °. QRS - T = 13 °. AR = + 50. The amplitude of the P wave = 1.5 mm. PII> PI> PIII. The P wave is two-phase, the first (positive) phase is greater than the second (negative).

QRS complex I, II, aVL type qRs. QRSIII type R, q, „aVL and SI, II are small. R, u slightly serrated on the descending knee. RS-type QRSV1-V3 complex (rS). QRSV4_v6 of type qRs. SV2 = 18 mm> SV3> SV5, rv1 wave RV5> RV6. The QRS transition zone is between leads V2 and V3. The RS segment - TV1-V3 is displaced upward from the isoelectric line by 1 - 2 mm. The RS segment - T in other leads at the level of the isoelectric line. Prong TII> TI> TIII. TV1 tooth is negative, TV2 is positive. TV2 TV4> TV5> TV6.

Normal electrocardiogram

The electrocardiogram is normal, regardless of the lead system, consists of three upward (positive) P, R and T waves, two downward (negative) waves and Q and S, and an inconsistent, upward U wave.

In addition, the ECG distinguishes between the intervals P-Q, S-T, T-P, R-R and two complexes - QRS and QRST (Fig. 10).

Rice. 10. Teeth and intervals of normal ECG

The P wave reflects atrial depolarization. The first half of the P wave corresponds to the excitation of the right atrium, the second half - to the excitation of the left atrium.

The P-Q interval corresponds to the period from the onset of atrial excitation to the onset of ventricular excitation. The PQ interval is measured from the beginning of the P wave to the beginning of the Q wave, in the absence of the Q wave, to the beginning of the R wave. It includes the duration of atrial excitation (the P wave itself) and the duration of the propagation of excitation mainly along the atrioventricular node, where there is a physiological delay in impulse conduction ( segment from the end of the P wave to the beginning of the Q wave). During the passage of the impulse through a specifically conducting system, such a small potential difference arises that it is not possible to detect any of its reflections on the ECG taken from the body surface. The P-Q interval is located on the isoelectric line, its duration is 0.12-0.18 s.

The QRS complex reflects the depolarization of the ventricles. The duration (width) of the QRS complex characterizes intraventricular conduction, which varies within normal limits depending on the heart rate (decreases with tachycardia, increases with bradycardia). The duration of the QRS complex is 0.06-0.09 s.

The Q wave corresponds to the excitation of the interventricular septum. Normally, it is absent in the right chest leads. A deep Q wave in lead III appears with a high position of the diaphragm, disappearing or decreasing with a deep breath. The duration of the Q wave does not exceed 0.03 s, its amplitude is no more than 1/4 of the R wave.

The R wave characterizes the excitation of the bulk of the ventricular myocardium, the S wave - the excitation of the posterior upper parts of the ventricles and the interventricular septum. An increase in the height of the R wave corresponds to a rise in potential within the electrode. At the moment when the entire myocardium adjacent to the electrode is depolarized, the potential difference disappears and the R wave reaches the isoelectric line or passes into the S wave located below it (internal deviation, or internal deflection). In unipolar leads, the segment of the QRS complex from the beginning of excitation (the beginning of the Q wave, and in its absence - the beginning of the R wave) to the apex of the R wave reflects the true excitation of the myocardium at this point. The duration of this segment is called the internal deviation time. This time depends on the speed of propagation of excitation and the thickness of the myocardium. Normally, it is 0.015-0.035 s for the right ventricle, and 0.035-0.045 s for the left ventricle. The time lag of internal deviation is used to diagnose myocardial hypertrophy, leg blockade and its localization.

When describing the QRS complex, in addition to the amplitude of its constituent teeth (mm) and duration (s), their letter designation is given. In this case, small teeth are designated in lower case letters, large in capital letters (Fig. 11).

Rice. 11. The most common forms of the complex and their letter designation

The S-T interval corresponds to the period of complete depolarization when there is no potential difference, and therefore is on the isoelectric line. A variant of the norm can be a displacement of the interval in standard leads by 0.5-1 mm. The length of the S-T interval varies widely with heart rate.

The T wave is the terminal part of the ventricular complex and corresponds to the phase of ventricular repolarization. It is directed upwards, has a gently sloping ascending knee, a rounded apex and a steeper descending knee, that is, it is asymmetrical. The duration of the T wave varies widely, averaging 0.12-0.16 s.

The QRST complex (Q-T interval) in time corresponds to the period from the beginning of depolarization to the end of repolarization of the ventricles and reflects their electrical systole.

Calculation of the Q-T interval can be performed using special tables. The duration of the QRST complex in normal conditions almost coincides with the duration of mechanical systole.

To characterize the electric systole of the heart, the systolic indicator SP is used - the ratio of the duration of the electric systole Q-T expressed as a percentage to the duration of the cardiac cycle R-R:

An increase in the systolic index by more than 5% above the norm may be one of the signs of an inferior function of the heart muscle.

The U wave occurs 0.04 s after the T wave. It is small, with normal amplification, it is not determined on all ECGs and mainly in leads V2-V4. The genesis of this prong is unclear. Perhaps it is a reflection of the trace potential in the phase of increased myocardial excitability after systole. The maximum amplitude of the U wave is normally 2.5 mm, the duration is 0.3 s.

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What ECG Draws

A conventional electrocardiographic study includes registration of EMF in 12 leads:

• standard leads (I, II, III);
• enhanced leads (aVR, aVL, aVF);
• chest leads (V1..V6).

In each lead, at least 4 ECG complexes (complete cycles) are recorded. In Russia, the standard for belt speed is 50 mm / s (abroad - 25 mm / s). At a belt speed of 50 mm / s, each small cell located between adjacent vertical lines (distance 1 mm) corresponds to an interval of 0.02 s. Every fifth vertical line on the electrocardiographic tape is thicker. The constant tape speed and the millimeter grid on paper allow you to measure the duration of ECG waves and intervals and the amplitude of these waves.

Due to the fact that the polarity of the lead axis aVR is opposite to the polarity of the axes of the standard leads, the EMF of the heart is projected onto the negative part of the axis of this lead. Therefore, in normal lead aVR, the P and T waves are negative, and the QRS complex looks like QS (less often rS).

The time of activation of the left and right ventricles is the period from the beginning of excitation of the ventricles to the coverage of the excitation of the maximum number of their muscle fibers. This is the time interval from the beginning of the QRS complex (from the beginning of the Q or R wave) to the perpendicular dropped from the top of the R wave to the isoline. The activation time of the left ventricle is determined in the left chest leads V5, V6 (the norm is no more than 0.04 s, or 2 cells). The activation time of the right ventricle is determined in the chest leads V1, V2 (the norm is no more than 0.03 s, or one and a half cells).

ECG teeth are denoted in Latin letters. If the amplitude of the prong is more than 5 mm, such a prong is indicated by a capital letter; if less than 5 mm - lowercase. As can be seen from the figure, a normal cardiogram consists of the following sections:

• P wave - atrial complex;
• PQ interval - time of passage of excitation through the atria to the ventricular myocardium;
• QRS complex - ventricular complex;
• wave q - excitation of the left half of the interventricular septum;
• R wave - the main wave of the ECG, due to the excitation of the ventricles;
• wave s - final excitation of the base of the left ventricle (non-constant wave of the ECG);
• ST segment - corresponds to the period of the cardiac cycle when both ventricles are engulfed in excitement;
• T wave - is recorded during repolarization of the ventricles;
• QT interval - electrical systole of the ventricles;
• u wave - the clinical origin of this wave is not exactly known (it is not always recorded);
• segment TP - diastole of the ventricles and atria.

P wave negative on ecg

Normal electrocardiogram

Any ECG consists of several waves, segments and intervals, reflecting the complex process of propagation of the excitation wave through the heart.

The shape of the electrocardiographic complexes and the size of the teeth are different in different leads and are determined by the size and direction of the projection of the moment vectors of the EMF of the heart on the axis of one or another lead. If the projection of the moment vector is directed towards the positive electrode of this lead, an upward deviation from the isoline is recorded on the ECG - positive teeth. If the projection of the vector is directed towards the negative electrode, the deviation downward from the isoline is recorded on the ECG - negative teeth. In the case when the moment vector is perpendicular to the lead axis, its projection onto this axis is zero and no deviations from the isoline are recorded on the ECG. If, during the cycle of excitation, the vector changes its direction in relation to the poles of the lead axis, then the tooth becomes biphasic.

The general scheme for decoding the ECG is presented below.

Segments and prongs of a normal ECG.

Prong R.

The P wave reflects the process of depolarization of the right and left atria. In a healthy person, in leads I, II, aVF, V-V, the P wave is always positive, in leads III and aVL, V it can be positive, biphasic, or (rarely) negative, and in lead aVR, the P wave is always negative. In leads I and II, the P wave has a maximum amplitude. The duration of the P wave does not exceed 0.1 s, and its amplitude is 1.5-2.5 mm.

P-Q (R) interval.

The P-Q (R) interval reflects the duration of atrioventricular conduction, i.e. the time of propagation of excitation through the atria, AV-node, bundle of His and its branches. Its duration is 0.12-0.20 s and in a healthy person depends mainly on the heart rate: the higher the heart rate, the shorter the P-Q (R) interval.

Ventricular QRST complex.

The ventricular QRST complex reflects the complex process of propagation (QRS complex) and extinction (RS segment - T and T wave) of excitation along the ventricular myocardium.

Q wave.

The Q wave can normally be recorded in all standard and enhanced unipolar leads from the limbs and in the chest leads V-V. The amplitude of a normal Q wave in all leads, except for aVR, does not exceed the height of the R wave, and its duration is 0.03 s. In lead aVR in a healthy person, a deep and wide Q wave or even a QS complex can be fixed.

R wave.

Normally, the R wave can be recorded in all standard and enhanced limb leads. In lead aVR, the R wave is often poorly expressed or absent altogether. In the chest leads, the amplitude of the R wave gradually increases from V to V, and then decreases slightly in V and V. Sometimes the r wave may be absent. Barb

R reflects the spread of excitation along the interventricular septum, and the R wave - along the muscle of the left and right ventricles. The interval of internal deviation in lead V does not exceed 0.03 s, and in lead V - 0.05 s.

S wave.

In a healthy person, the amplitude of the S wave in various electrocardiographic leads fluctuates within wide limits, not exceeding 20 mm. In the normal position of the heart in the chest in the leads from the extremities, the S amplitude is small, except for lead aVR. In the chest leads, the S wave gradually decreases from V, V to V, and in leads V, V it has little or no amplitude. Equality of the R and S waves in the chest leads ("transition zone") is usually recorded in lead V or (less often) between V and V or V and V.

The maximum duration of the ventricular complex does not exceed 0.10 s (usually 0.07-0.09 s).

Segment RS-T.

The RS-T segment in a healthy person in the limb leads is located on the isoline (0.5 mm). Normally, in the chest leads V-V, there may be a slight displacement of the RS-T segment upward from the isoline (no more than 2 mm), and in leads V - downward (no more than 0.5 mm).

T wave.

Normally, the T wave is always positive in leads I, II, aVF, V-V, with T> T and T> T. In leads III, aVL and V, the T wave can be positive, biphasic, or negative. In lead aVR, the T wave is normally always negative.

Q-T interval (QRST)

The Q-T interval is called electrical ventricular systole. Its duration depends primarily on the number of heartbeats: the higher the heart rate, the shorter the proper Q-T interval. The normal duration of the Q-T interval is determined by the Bazett formula: Q-T = K, where K is a coefficient equal to 0.37 for men and 0.40 for women; R-R is the duration of one cardiac cycle.

Analysis of the electrocardiogram.

Analysis of any ECG should begin with checking the correctness of the technique for its registration. First, you need to pay attention to the presence of a variety of interference. Interference arising from ECG registration:

a - flood currents - mains induction in the form of regular oscillations with a frequency of 50 Hz;

b - “swimming” (drift) of the isoline as a result of poor contact of the electrode with the skin;

c - pickup caused by muscle tremor (irregular frequent fluctuations are visible).

Interference arising from ECG registration

Secondly, it is necessary to check the amplitude of the reference millivolt, which should correspond to 10mm.

Third, the paper speed should be assessed during ECG recording. When recording an ECG at a speed of 50mm s 1mm on paper tape corresponds to a time interval of 0.02s, 5mm - 0.1s, 10mm - 0.2s, 50mm - 1.0s.

General scheme (plan) for decoding the ECG.

I. Analysis of heart rate and conduction:

1) assessment of the regularity of heart contractions;

2) counting the number of heartbeats;

3) determination of the source of excitation;

4) evaluation of the conductivity function.

II. Determination of turns of the heart around the anteroposterior, longitudinal and transverse axes:

1) determination of the position of the electrical axis of the heart in the frontal plane;

2) determination of turns of the heart around the longitudinal axis;

3) determination of turns of the heart around the transverse axis.

III. Analysis of the atrial R.

IV. Ventricular QRST Analysis:

1) analysis of the QRS complex,

2) analysis of the RS-T segment,

3) analysis of the Q-T interval.

V. Electrocardiographic conclusion.

I.1) The regularity of heartbeats is assessed by comparing the duration of the R-R intervals between successively recorded cardiac cycles. The R-R interval is usually measured between the tops of the R waves. Regular, or correct, heart rhythm is diagnosed if the duration of the measured R-R is the same and the spread of the values ​​obtained does not exceed 10% of the average R-R duration. In other cases, the rhythm is considered abnormal (irregular), which can be observed with extrasystole, atrial fibrillation, sinus arrhythmia, etc.

2) With the correct rhythm, the heart rate (HR) is determined by the formula: HR =.

With an irregular rhythm, an ECG in one of the leads (most often in standard lead II) is recorded longer than usual, for example, within 3-4 seconds. Then the number of QRS complexes registered in 3 s is counted, and the result is multiplied by 20.

In a healthy person at rest, the heart rate is from 60 to 90 per minute. An increase in heart rate is called tachycardia, and a decrease in heart rate is called bradycardia.

Assessment of the regularity of the rhythm and heart rate:

a) correct rhythm; b) c) wrong rhythm

3) To determine the source of excitation (pacemaker), it was necessary to assess the course of excitation in the atria and establish the ratio of the R waves to the ventricular QRS complexes.

Sinus rhythm is characterized by: the presence of positive H waves in lead II, preceding each QRS complex; constant identical shape of all P waves in the same lead.

In the absence of these signs, various variants of the non-sinus rhythm are diagnosed.

Atrial rhythm (from the lower atria) is characterized by the presence of negative P, P waves and unchanged QRS complexes following them.

The rhythm from the AV connection is characterized by: the absence of a P wave on the ECG, merging with the usual unchanged QRS complex, or the presence of negative P waves located after the usual unchanged QRS complexes.

The ventricular (idioventricular) rhythm is characterized by: a slow ventricular rate (less than 40 beats per minute); the presence of expanded and deformed QRS complexes; the absence of a natural connection between the QRS complexes and the P waves.

4) For a rough preliminary assessment of the conduction function, it is necessary to measure the duration of the P wave, the duration of the P-Q (R) interval and the total duration of the ventricular QRS complex. An increase in the duration of these teeth and intervals indicates a slowdown in conduction in the corresponding section of the cardiac conduction system.

II. Determination of the position of the electrical axis of the heart. There are the following options for the position of the electrical axis of the heart:

Bailey's six-axis system.

a) Determination of the angle by graphical method. Calculate the algebraic sum of the amplitudes of the QRS complex teeth in any two leads from the limbs (usually I and III standard leads are used), the axes of which are located in the frontal plane. The positive or negative value of the algebraic sum in an arbitrarily chosen scale is plotted on the positive or negative part of the axis of the corresponding lead in the six-axis Bailey coordinate system. These values ​​represent the projection of the desired electrical axis of the heart on the axis I and III of the standard leads. From the ends of these projections, the perpendiculars to the lead axes are restored. The intersection point of the perpendiculars is connected to the center of the system. This line is the electrical axis of the heart.

b) Visual determination of the angle. Allows you to quickly estimate the angle with an accuracy of 10 °. The method is based on two principles:

1. The maximum positive value of the algebraic sum of the teeth of the QRS complex is observed in that lead, the axis of which approximately coincides with the location of the electrical axis of the heart, parallel to it.

2. A complex of the RS type, where the algebraic sum of the teeth is equal to zero (R = S or R = Q + S), is recorded in the lead, the axis of which is perpendicular to the electrical axis of the heart.

In the normal position of the electrical axis of the heart: RRR; in leads III and aVL, the R and S waves are approximately equal to each other.

With a horizontal position or deviation of the electrical axis of the heart to the left: high R teeth are fixed in leads I and aVL, with R> R> R; a deep S wave is recorded in lead III.

With an upright position or deviation of the electrical axis of the heart to the right: high R waves are recorded in leads III and aVF, with R R> R; deep S waves are recorded in leads I and aV

III. Analysis of the P wave includes: 1) measuring the amplitude of the P wave; 2) measuring the duration of the P wave; 3) determination of the polarity of the P wave; 4) determination of the shape of the P wave.

IV.1) Analysis of the QRS complex includes: a) assessment of the Q wave: amplitude and comparison with the R amplitude, duration; b) evaluation of the R wave: the amplitude, comparing it with the amplitude of Q or S in the same lead and with R in other leads; the duration of the interval of internal deviation in leads V and V; possible splitting of a tooth or the appearance of an additional one; c) evaluation of the S wave: amplitude, comparing it with the amplitude R; possible widening, serration or splitting of the tooth.

2) When analyzing the RS-T segment, it is necessary to: find the junction point j; measure its deviation (+ -) from the isoline; measure the magnitude of the displacement of the RS-T segment of the isoline up or down at a point located from point j to the right by 0.05-0.08 s; determine the shape of a possible displacement of the RS-T segment: horizontal, oblique, oblique.

3) When analyzing the T wave, you should: determine the polarity of T, evaluate its shape, measure the amplitude.

4) Analysis of the Q-T interval: measurement of duration.

V. Electrocardiographic conclusion:

1) the source of the heart rate;

2) the regularity of the heart rhythm;

4) the position of the electrical axis of the heart;

5) the presence of four electrocardiographic syndromes: a) cardiac arrhythmias; b) conduction disturbances; c) hypertrophy of the myocardium of the ventricles and atria or their acute overload; d) myocardial damage (ischemia, dystrophy, necrosis, scarring).

Electrocardiogram for cardiac arrhythmias

1. Violations of the automatism of the CA-node (nomotopic arrhythmias)

1) Sinus tachycardia: an increase in the number of heart contractions up to (180) per minute (shortening of the R-R intervals); maintaining the correct sinus rhythm (correct alternation of the P wave and the QRST complex in all cycles and a positive P wave).

2) Sinus bradycardia: a decrease in the number of heart contractions per minute (an increase in the duration of the R-R intervals); maintaining the correct sinus rhythm.

3) Sinus arrhythmia: fluctuations in the duration of the R-R intervals, exceeding 0.15 s and associated with the phases of breathing; preservation of all electrocardiographic signs of sinus rhythm (alternation of the P wave and the QRS-T complex).

4) Syndrome of weakness of the sinus node: persistent sinus bradycardia; periodic appearance of ectopic (non-sinus) rhythms; the presence of a SA blockade; bradycardia-tachycardia syndrome.

a) ECG of a healthy person; b) sinus bradycardia; c) sinus arrhythmia

2. Extrasystole.

1) Atrial extrasystole: premature extraordinary appearance of the P 'wave and the following QRST' complex; deformation or change in the polarity of the P 'wave of the extrasystole; the presence of an unchanged extrasystolic ventricular complex QRST ′, similar in shape to the usual normal complexes; the presence of an incomplete compensatory pause after an atrial extrasystole.

Atrial premature beats (II standard lead): a) from the upper atria; b) from the middle sections of the atria; c) from the lower atria; d) blocked atrial premature beats.

2) Extrasystoles from the atrioventricular junction: premature extraordinary appearance on the ECG of an unchanged ventricular QRS complex, similar in shape to the rest of the QRST complexes of sinus origin; negative P 'wave in leads II, III and aVF after extrasystolic QRS' complex or absence of P 'wave (fusion of P' and QRS '); the presence of an incomplete compensatory pause.

3) Ventricular extrasystole: premature extraordinary appearance on the ECG of the altered ventricular QRS complex; significant expansion and deformation of the extrasystolic QRS 'complex; the location of the RS-T ′ segment and the T ′ tooth of the extrasystole is discordant to the direction of the main tooth of the QRS ′ complex; the absence of a P wave before the ventricular extrasystole; the presence in most cases after a ventricular extrasystole of a full compensatory pause.

a) left ventricular; b) right ventricular extrasystole

3. Paroxysmal tachycardia.

1) Atrial paroxysmal tachycardia: a sudden onset and also suddenly ending attack of increased heart rate up to a minute while maintaining the correct rhythm; the presence of a reduced, deformed, biphasic or negative P wave in front of each ventricular QRS complex; normal unchanged ventricular QRS complexes; in some cases, there is a deterioration in atrioventricular conduction with the development of I degree atrioventricular block with periodic drops of individual QRS complexes (intermittent signs).

2) Paroxysmal tachycardia from the atrioventricular junction: a sudden onset and also suddenly ending attack of increased heart rate up to a minute while maintaining the correct rhythm; the presence of negative P 'waves in leads II, III and aVF, located behind the QRS' complexes or merging with them and not recorded on the ECG; normal unchanged ventricular QRS complexes'.

3) Ventricular paroxysmal tachycardia: a sudden onset and also suddenly ending attack of increased heart rate up to a minute while maintaining the correct rhythm in most cases; deformation and expansion of the QRS complex for more than 0.12 s with discordant location of the RS-T segment and the T wave; the presence of atrioventricular dissociation, i.e. complete dissociation of the frequent ventricular rhythm and normal atrial rhythm with occasionally recorded single normal unchanged QRST complexes of sinus origin.

4. Atrial flutter: the presence on the ECG of frequent - for a minute - regular, similar atrial F waves with a characteristic sawtooth shape (leads II, III, aVF, V, V); in most cases, correct, regular ventricular rhythm at regular F-F intervals; the presence of normal unchanged ventricular complexes, each of which is preceded by a certain number of atrial F waves (2: 1, 3: 1, 4: 1, etc.).

5. Atrial fibrillation (fibrillation): the absence of the P wave in all leads; the presence throughout the entire cardiac cycle of irregular waves f having different shapes and amplitudes; the waves f better recorded in leads V, V, II, III and aVF; irregularity of ventricular QRS complexes - irregular ventricular rhythm; the presence of QRS complexes, which in most cases have a normal unchanged appearance.

a) coarse-wavy form; b) fine-wavy form.

6. Ventricular flutter: frequent (up to a minute), regular and identical in shape and amplitude, flutter waves, resembling a sinusoidal curve.

7. Flicker (fibrillation) of the ventricles: frequent (from 200 to 500 per minute), but irregular waves, differing from each other in different shapes and amplitudes.

Electrocardiogram for violations of the conduction function.

1. Sinoatrial blockade: periodic loss of individual cardiac cycles; an increase at the time of cardiac cycles loss of a pause between two adjacent P or R waves by almost 2 times (less often 3 or 4 times) compared to the usual P-P or R-R intervals.

2. Intra-atrial block: an increase in the duration of the P wave more than 0.11 s; cleavage of the P wave.

3. Atrioventricular blockade.

1) I degree: an increase in the duration of the interval P-Q (R) more than 0.20 s.

a) atrial form: expansion and cleavage of the P wave; QRS of normal form.

b) nodular form: lengthening of the P-Q (R) segment.

c) distal (three-beam) form: pronounced deformation of the QRS.

2) II degree: prolapse of individual ventricular QRST complexes.

a) Mobitz type I: gradual lengthening of the P-Q (R) interval with subsequent loss of QRST. After an extended pause - again a normal or slightly lengthened P-Q (R), after which the whole cycle is repeated.

b) Mobitz type II: QRST prolapse is not accompanied by a gradual lengthening of P-Q (R), which remains constant.

c) Mobitz type III (incomplete AV block): either every second (2: 1), or two or more ventricular complexes in a row (block 3: 1, 4: 1, etc.).

3) III degree: complete separation of the atrial and ventricular rhythms and a decrease in the number of ventricular contractions up to a minute or less.

4. Blockade of the legs and branches of the His bundle.

1) Blockade of the right leg (branch) of the His bundle.

a) Complete blockade: the presence in the right chest leads V (less often in leads from the extremities III and aVF) of the QRS complexes of the rSR ′ or rSR ′ type, having an M-shaped appearance, and R ′> r; the presence of a widened, often serrated S wave in the left chest leads (V, V) and leads I, aVL; an increase in the duration (width) of the QRS complex more than 0.12 s; the presence in lead V (less often in III) of depression of the RS-T segment with a convexity facing upward, and a negative or biphasic (- +) asymmetric T wave.

b) Incomplete blockade: the presence of a QRS complex of the rSr ′ or rSR ′ type in lead V, and a slightly widened S wave in leads I and V; the duration of the QRS complex is 0.09-0.11 s.

2) Blockade of the left anterior branch of the His bundle: a sharp deviation of the electrical axis of the heart to the left (angle α –30 °); QRS in leads I, aVL type qR, III, aVF, II type rS; the total duration of the QRS complex is 0.08-0.11 s.

3) Blockade of the left posterior branch of the His bundle: a sharp deviation of the electrical axis of the heart to the right (angle α120 °); the form of the QRS complex in leads I and aVL of the rS type, and in leads III, aVF - of the qR type; the duration of the QRS complex is within 0.08-0.11 s.

4) Blockade of the left bundle branch of His: in leads V, V, I, aVL, broadened deformed ventricular complexes of the R type with a split or wide apex; in leads V, V, III, aVF, broadened deformed ventricular complexes that look like QS or rS with a split or wide apex of the S wave; an increase in the total duration of the QRS complex by more than 0.12 s; the presence in leads V, V, I, aVL discordant with respect to the QRS displacement of the RS-T segment and negative or biphasic (- +) asymmetric T waves; deviation of the electrical axis of the heart to the left is often observed, but not always.

5) Blockade of three branches of the His bundle: atrioventricular blockade of I, II or III degree; blockade of two branches of the bundle of His.

Electrocardiogram for atrial and ventricular hypertrophy.

1. Hypertrophy of the left atrium: bifurcation and an increase in the amplitude of the P waves (P-mitrale); an increase in the amplitude and duration of the second negative (left atrial) phase of the P wave in lead V (less often V) or the formation of negative P; negative or biphasic (+ -) P wave (non-permanent sign); increase in the total duration (width) of the P wave - more than 0.1 s.

2. Hypertrophy of the right atrium: in leads II, III, aVF, the P waves are high-amplitude, with a pointed apex (P-pulmonale); in leads V, the P wave (or at least its first - the right atrial phase) is positive with a pointed apex (P-pulmonale); in leads I, aVL, V, the P wave of low amplitude, and in aVL it can be negative (non-permanent sign); the duration of the P waves does not exceed 0.10 s.

3. Left ventricular hypertrophy: an increase in the amplitude of the R and S waves. In this case, R2 25mm; signs of rotation of the heart around the longitudinal axis counterclockwise; displacement of the electrical axis of the heart to the left; displacement of the RS-T segment in leads V, I, aVL below the isoline and the formation of a negative or biphasic (- +) T wave in leads I, aVL and V; an increase in the duration of the interval of internal QRS deviation in the left chest leads by more than 0.05 s.

4. Hypertrophy of the right ventricle: displacement of the electrical axis of the heart to the right (angle α more than 100 °); an increase in the amplitude of the R wave in V and the S wave in V; the appearance in lead V of the QRS complex of the rSR ′ or QR type; signs of rotation of the heart around the longitudinal axis in a clockwise direction; displacement of the RS-T segment downward and the appearance of negative T waves in leads III, aVF, V; an increase in the duration of the interval of internal deviation in V more than 0.03 s.

Electrocardiogram for ischemic heart disease.

1. The acute stage of myocardial infarction is characterized by the rapid, within 1-2 days, the formation of a pathological Q wave or QS complex, displacement of the RS-T segment above the isoline and merging with it at first positive and then negative T wave; in a few days the RS-T segment approaches the isoline. At the 2-3rd week of the disease, the RS-T segment becomes isoelectric, and the negative coronary T wave sharply deepens and becomes symmetrical, pointed.

2. In the subacute stage of myocardial infarction, a pathological Q wave or QS complex (necrosis) and a negative coronary T wave (ischemia) are recorded, the amplitude of which gradually decreases starting from the day. The RS-T segment is located on the isoline.

3. The cicatricial stage of myocardial infarction is characterized by persistence for a number of years, often throughout the patient's life, of a pathological Q wave or QS complex and the presence of a weakly negative or positive T wave.

7.2.1. Myocardial hypertrophy

Hypertrophy is usually caused by an excessive load on the heart, either by resistance (arterial hypertension) or volume (chronic renal and / or heart failure). The increased work of the heart leads to an increase in metabolic processes in the myocardium and is further accompanied by an increase in the number of muscle fibers. The bioelectrical activity of the hypertrophied part of the heart increases, which is reflected in the electrocardiogram.

7.2.1.1. Left atrial hypertrophy

A characteristic sign of left atrial hypertrophy is an increase in the width of the P wave (more than 0.12 s). The second sign is a change in the shape of the P wave (two humps with a predominance of the second apex) (Fig. 6).

Rice. 6. ECG with left atrial hypertrophy

Left atrial hypertrophy is a typical symptom of mitral stenosis and therefore the P wave in this disease is called P-mitrale. Similar changes are observed in leads I, II, aVL, V5, V6.

7.2.1.2. Right atrial hypertrophy

With hypertrophy of the right atrium, the changes also concern the P wave, which acquires a pointed shape and increases in amplitude (Fig. 7).

Rice. 7. ECG for hypertrophy of the right atrium (P-pulmonale), right ventricle (S-type)

Hypertrophy of the right atrium is observed with atrial septal defect, hypertension of the pulmonary circulation.

Most often, such a P wave is detected in lung diseases, it is often called P-pulmonale.

Right atrial hypertrophy is a sign of changes in the P wave in leads II, III, aVF, V1, V2.

7.2.1.3. Left ventricular hypertrophy

The ventricles of the heart are better adapted to stress, and in the early stages their hypertrophy may not appear on the ECG, but as the pathology develops, characteristic signs become visible.

With ventricular hypertrophy, the ECG shows significantly more changes than with atrial hypertrophy.

The main signs of left ventricular hypertrophy are (Fig. 8):

Deviation of the electrical axis of the heart to the left (levogram);

Displacement of the transition zone to the right (in leads V2 or V3);

The R wave in leads V5, V6 is high and larger in amplitude than RV4;

Deep S in leads V1, V2;

Extended QRS complex in leads V5, V6 (up to 0.1 s or more);

Displacement of the S-T segment below the isoelectric line with a bulge upward;

Negative T wave in leads I, II, aVL, V5, V6.

Rice. 8. ECG with left ventricular hypertrophy

Left ventricular hypertrophy is often observed with arterial hypertension, acromegaly, pheochromocytoma, as well as insufficiency of the mitral and aortic valves, congenital heart defects.

7.2.1.4. Right ventricular hypertrophy

Signs of right ventricular hypertrophy appear on the ECG in advanced cases. Diagnosis at an early stage of hypertrophy is extremely difficult.

Signs of hypertrophy (Fig. 9):

Deviation of the electrical axis of the heart to the right (pravogram);

Deep S wave in lead V1 and high R wave in leads III, aVF, V1, V2;

The height of the RV6 tooth is less than normal;

Extended QRS complex in leads V1, V2 (up to 0.1 s or more);

Deep S wave in lead V5 as well as V6;

Displacement of the ST segment below the isoline with a bulge upward in the right III, aVF, V1 and V2;

Complete or incomplete right bundle branch block;

Offset of the transition zone to the left.

Rice. 9. ECG with right ventricular hypertrophy

Right ventricular hypertrophy is most often associated with increased pressure in the pulmonary circulation in diseases of the lungs, mitral valve stenosis, parietal thrombosis and pulmonary artery stenosis and congenital heart defects.

7.2.2. Rhythm disturbances

Weakness, shortness of breath, heart palpitations, rapid and difficult breathing, heart failure, choking sensation, fainting, or episodes of loss of consciousness can be manifestations of cardiac arrhythmias due to cardiovascular disease. ECG helps to confirm their presence, and most importantly to determine their type.

It should be remembered that automatism is a unique property of the cells of the cardiac conduction system, and the sinus node, which controls the rhythm, has the greatest automatism.

Arrhythmias (arrhythmias) are diagnosed when there is no sinus rhythm on the ECG.

Signs of normal sinus rhythm:

The frequency of the P waves is in the range from 60 to 90 (in 1 min);

Same duration of P-P intervals;

Positive P wave in all leads except aVR.

Heart rhythm disturbances are very diverse. All arrhythmias are divided into nomotopic (changes develop in the sinus node itself) and heterotopic. In the latter case, excitatory impulses arise outside the sinus node, that is, in the atria, atrioventricular junction and ventricles (in the branches of the His bundle).

Nomotopic arrhythmias include sinus brady and tachycardia and irregular sinus rhythm. To heterotopic - atrial fibrillation and flutter and other disorders. If the occurrence of arrhythmia is associated with impaired excitability, then such rhythm disturbances are divided into extrasystole and paroxysmal tachycardia.

Considering all the variety of arrhythmias that can be detected on an ECG, the author, in order not to tire the reader with the intricacies of medical science, allowed himself only to define the basic concepts and consider the most significant rhythm and conduction disturbances.

7.2.2.1. Sinus tachycardia

Increased generation of impulses in the sinus node (more than 100 impulses per minute).

On the ECG, it is manifested by the presence of a conventional P wave and a shortening of the R-R interval.

7.2.2.2. Sinus bradycardia

The pulse generation frequency in the sinus node does not exceed 60.

On the ECG, it is manifested by the presence of a conventional P wave and an extension of the R-R interval.

It should be noted that with a frequency of contractions of less than 30, the bradycardia is not sinus.

As in the case of tachycardia and bradycardia, the patient is treated for the disease that caused the rhythm disturbance.

7.2.2.3. Irregular sinus rhythm

Pulses are irregularly generated in the sinus node. The ECG shows normal waves and intervals, but the duration of the R-R intervals differs by at least 0.1 s.

This type of arrhythmia can occur in healthy people and does not need treatment.

7.2.2.4. Idioventricular rhythm

Heterotopic arrhythmia, in which the pacemaker is either the legs of the bundle of His or Purkinje fibers.

Extremely severe pathology.

There is a rare rhythm on the ECG (that is, 30–40 beats per minute), the P wave is absent, the QRS complexes are deformed and expanded (duration 0.12 s or more).

It occurs only in severe heart disease. A patient with such a disorder requires urgent care and is subject to immediate hospitalization in cardiological intensive care.

Extraordinary contraction of the heart caused by a single ectopic impulse. The division of extrasystoles into supraventricular and ventricular is of practical importance.

The supraventricular (also called atrial) extrasystole is recorded on the ECG if the focus causing extraordinary excitation (contraction) of the heart is in the atria.

The ventricular extrasystole is recorded on the cardiogram during the formation of an ectopic focus in one of the ventricles.

Extrasystole can be rare, frequent (more than 10% of heart contractions in 1 min), steam (bigemenia) and group (more than three in a row).

We list the ECG signs of atrial extrasystoles:

P wave modified in shape and amplitude;

Shortened P-Q interval;

Prematurely recorded QRS complex does not differ in shape from the normal (sinus) complex;

The R-R interval that follows the extrasystole is longer than usual, but shorter than two normal intervals (incomplete compensatory pause).

Atrial extrasystoles are more common in older people against the background of cardiosclerosis and coronary heart disease, but they can also be observed in practically healthy people, for example, if a person is very worried or is under stress.

If an extrasystole is seen in a practically healthy person, then the treatment consists in prescribing valocordin, corvalol and ensuring complete rest.

When registering an extrasystole, a patient also requires treatment of the underlying disease and taking antiarrhythmic drugs from the isoptin group.

Signs of a ventricular extrasystole:

The P wave is absent;

Extraordinary QRS complex is significantly expanded (more than 0.12 s) and deformed;

Full compensatory pause.

Ventricular extrasystole always indicates heart damage (coronary artery disease, myocarditis, endocarditis, heart attack, atherosclerosis).

With ventricular extrasystole with a frequency of 3-5 contractions per 1 min, antiarrhythmic therapy is required.

Most often, lidocaine is injected intravenously, but other drugs are also possible. Treatment is carried out with careful ECG monitoring.

7.2.2.6. Paroxysmal tachycardia

A sudden attack of super-frequent contractions, lasting from a few seconds to several days. The heterotopic pacemaker is located either in the ventricles or supraventricularly.

With supraventricular tachycardia (in this case, impulses are formed in the atria or atrioventricular node), the correct rhythm is recorded on the ECG with a frequency of 180 to 220 beats per minute.

QRS complexes are not changed or expanded.

With a ventricular form of paroxysmal tachycardia, the P waves can change their place on the ECG, the QRS complexes are deformed and expanded.

Supraventricular tachycardia occurs in Wolff-Parkinson-White syndrome, less often in acute myocardial infarction.

The ventricular form of paroxysmal tachycardia is detected in patients with myocardial infarction, with ischemic heart disease, electrolyte metabolism disorders.

7.2.2.7. Atrial fibrillation (atrial fibrillation)

A type of supraventricular arrhythmias caused by asynchronous, uncoordinated electrical activity of the atria with a subsequent deterioration in their contractile function. The flow of impulses is not conducted to the entire ventricles, and they contract irregularly.

This arrhythmia is one of the most common heart rhythm disturbances.

It occurs in more than 6% of patients over 60 years of age and in 1% of patients younger than this age.

Signs of atrial fibrillation:

R-R intervals are different (arrhythmia);

P waves are absent;

Flickering waves are recorded (they are especially clearly visible in leads II, III, V1, V2);

Electrical alternation (different amplitude of the I waves in one lead).

Atrial fibrillation occurs with mitral stenosis, thyrotoxicosis and cardiosclerosis, as well as often with myocardial infarction. Medical assistance consists in restoring sinus rhythm. Novocainamide, potassium preparations and other antiarrhythmic drugs are used.

7.2.2.8. Atrial flutter

It is observed much less frequently than atrial fibrillation.

With atrial flutter, there is no normal excitement and contraction of the atria and there is excitement and contraction of individual atrial fibers.

7.2.2.9. Ventricular fibrillation

The most dangerous and severe rhythm disturbance, which quickly leads to a cessation of blood circulation. It occurs in myocardial infarction, as well as in the terminal stages of various cardiovascular diseases in patients who are in a state of clinical death. With ventricular fibrillation, urgent resuscitation is needed.

Signs of ventricular fibrillation:

Absence of all teeth of the ventricular complex;

Registration of fibrillation waves in all leads with a frequency of 450-600 waves per minute.

7.2.3. Conduction disturbances

Changes in the cardiogram that occur in the event of impulse conduction disturbance in the form of a slowdown or complete cessation of the transmission of excitation are called blockades. Blockages are classified according to the level at which the violation occurs.

Allocate sinoatrial, atrial, atrioventricular and intraventricular blockade. Each of these groups is further subdivided. So, for example, there are sinoatrial blockades of the I, II and III degree, blockade of the right and left legs of the His bundle. There is also a more detailed division (blockade of the anterior branch of the left bundle branch, incomplete right bundle branch block). Among the conduction disturbances recorded using an ECG, the following blockades are of the greatest practical importance:

Sinoatrial grade III;

Atrioventricular I, II and III degrees;

Right and left bundle branch block.

7.2.3.1. Sinoatrial block III degree

Conduction disorder, in which the conduction of excitation from the sinus node to the atria is blocked. On a seemingly normal ECG, the next contraction suddenly drops out (is blocked), that is, the entire P-QRS-T complex (or 2-3 complexes at once). An isoline is recorded in their place. Pathology is observed in patients with coronary artery disease, heart attack, cardiosclerosis, with the use of a number of drugs (for example, beta-blockers). Treatment consists in the treatment of the underlying disease and the use of atropine, izadrin and similar agents).

7.2.3.2. Atrioventricular block

Violation of the conduction of excitation from the sinus node through the atrioventricular connection.

Deceleration of atrioventricular conduction is a grade I atrioventricular block. It manifests itself on the ECG in the form of an extension of the P-Q interval (more than 0.2 s) at normal heart rate.

II degree atrioventricular block is an incomplete block in which not all impulses coming from the sinus node reach the ventricular myocardium.

On the ECG, the following two types of blockade are distinguished: the first is Mobitz-1 (Samoilova-Wenckebach) and the second is Mobitz-2.

Signs of a blockade of the Mobitz-1 type:

Constantly lengthening interval P

Due to the first sign, at some stage after the P wave, the QRS complex disappears.

A sign of a blockade of the Mobitz-2 type is a periodic loss of the QRS complex against the background of an extended P-Q interval.

III degree atrioventricular block is a condition in which not a single impulse coming from the sinus node is conducted to the ventricles. On the ECG, two types of rhythm are recorded that are not connected with each other, the work of the ventricles (QRS complexes) and the atria (P waves) is not coordinated.

Blockade III degree is often found in cardiosclerosis, myocardial infarction, improper use of cardiac glycosides. The presence of this type of blockade in a patient is an indication for his urgent hospitalization in a cardiological hospital. For treatment, atropine, ephedrine and, in some cases, prednisone are used.

7.2.Z.Z. Bundle branch block

In a healthy person, an electrical impulse originating in the sinus node, passing along the legs of the His bundle, simultaneously excites both ventricles.

With a blockade of the right or left bundle branch, the path of the impulse changes and therefore the excitation of the corresponding ventricle is delayed.

It is also possible the occurrence of incomplete blocks and the so-called blockades of the anterior and posterior branches of the bundle branch.

Signs of complete blockade of the right bundle branch (Fig. 10):

Deformed and expanded (more than 0.12 s) QRS complex;

Negative T wave in leads V1 and V2;

Displacement of the S-T segment from the isoline;

Expansion and cleavage of the QRS in leads V1 and V2 in the form of RsR.

Rice. 10. ECG with complete blockade of the right bundle branch

Signs of complete left bundle branch block:

The QRS complex is deformed and widened (more than 0.12 s);

Displacement of the S-T segment from the isoline;

Negative T wave in leads V5 and V6;

Expansion and cleavage of the QRS complex in leads V5 and V6 in the form of RR;

Deformation and expansion of the QRS in leads V1 and V2 in the form of rS.

These types of blockades are found in heart trauma, acute myocardial infarction, atherosclerotic and myocarditis cardiosclerosis, with the improper use of a number of medications (cardiac glycosides, novocainamide).

Patients with intraventricular block do not need special therapy. They are hospitalized for treatment of the disease that caused the blockade.

7.2.4. Wolff-Parkinson-White syndrome

For the first time such a syndrome (WPW) was described by the aforementioned authors in 1930 as a form of supraventricular tachycardia, which is observed in young healthy people ("functional bundle branch block").

It has now been established that in the body sometimes, in addition to the normal pathway of the impulse from the sinus node to the ventricles, there are additional bundles (Kent, James and Mahaim). Along these paths, excitation reaches the ventricles of the heart faster.

There are several types of WPW syndrome. If the excitation enters the left ventricle earlier, then the type A WPW syndrome is recorded on the ECG. In type B, excitation enters the right ventricle earlier.

Signs of WPW type A syndrome:

The delta wave on the QRS complex is positive in the right chest leads and negative in the left (the result of premature excitation of a part of the ventricle);

The direction of the main teeth in the chest leads is approximately the same as in the blockade of the left bundle branch.

Signs of WPW type B syndrome:

Shortened (less than 0.11 s) P-Q interval;

The QRS complex is widened (more than 0.12 s) and deformed;

Negative delta wave for the right chest leads, positive for the left;

The direction of the main teeth in the chest leads is approximately the same as in the blockade of the right bundle branch.

It is possible to register a sharply shortened P-Q interval with an undeformed QRS complex and the absence of a delta wave (Laun-Ganong-Levin syndrome).

Additional bundles are inherited. In about 30-60% of cases, they do not show themselves. Some people may develop paroxysms of tachyarrhythmias. In the event of arrhythmias, medical care is provided in accordance with the general rules.

7.2.5. Early ventricular repolarization

This phenomenon occurs in 20% of patients with cardiovascular pathology (most often occurs in patients with supraventricular heart rhythm disturbances).

This is not a disease, but patients with cardiovascular diseases who have this syndrome are 2–4 times more likely to suffer from rhythm and conduction disturbances.

Signs of early ventricular repolarization (Fig. 11) include:

Elevation of the ST segment;

Late delta wave (notch on the descending R wave);

High amplitude teeth;

Double-humped P wave of normal duration and amplitude;

Shortening of PR and QT intervals;

Rapid and sharp increase in the amplitude of the R wave in the chest leads.

Rice. 11. ECG in the syndrome of early repolarization of the ventricles

7.2.6. Cardiac ischemia

With ischemic heart disease (CHD), the blood supply to the myocardium is impaired. In the early stages, there may be no changes on the electrocardiogram; in the later stages, they are very noticeable.

With the development of myocardial dystrophy, the T wave changes and signs of diffuse changes in the myocardium appear.

These include:

Decrease in the amplitude of the R wave;

Depression of the S-T segment;

Biphasic, moderately widened and flat T wave in almost all leads.

IHD occurs in patients with myocarditis of various origins, as well as dystrophic changes in the myocardium and atherosclerotic cardiosclerosis.

With the development of an attack of angina on the ECG, it is possible to reveal a displacement of the S-T segment and changes in the T wave in those leads that are located above the zone with impaired blood supply (Fig. 12).

Rice. 12. ECG for angina pectoris (during an attack)

The causes of angina pectoris are hypercholesterolemia, dyslipidemia. In addition, arterial hypertension, diabetes mellitus, psycho-emotional overload, fear, obesity can provoke the development of an attack.

Depending on in which layer of the heart muscle ischemia occurs, there are:

Subendocardial ischemia (above the ischemic area, the S-T shift below the isoline, the T wave is positive, large amplitude);

Subepicardial ischemia (elevation of the ST segment above the isoline, T negative).

The onset of angina pectoris is accompanied by the appearance of typical chest pain, usually provoked by physical exertion. This pain has a pressing character, lasts several minutes and disappears after the use of nitroglycerin. If the pain lasts more than 30 minutes and is not relieved by taking nitro drugs, it is highly likely that acute focal changes can be assumed.

Emergency care for angina pectoris is to relieve pain and prevent recurrence.

Analgesics (from analgin to promedol), nitro drugs (nitroglycerin, sustac, nitrong, monochinque, etc.), as well as validol and diphenhydramine, seduxen are prescribed. If necessary, inhalation of oxygen is carried out.

7.2.8. Myocardial infarction

Myocardial infarction is the development of necrosis of the heart muscle as a result of prolonged circulatory disorders in the ischemic area of ​​the myocardium.

In more than 90% of cases, the diagnosis is made using an ECG. In addition, the cardiogram allows you to determine the stage of the heart attack, find out its localization and type.

An unconditional sign of a heart attack is the appearance on the ECG of a pathological Q wave, which is characterized by excessive width (more than 0.03 s) and greater depth (one third of the R wave).

The options are QS, QrS. S-T displacement (Fig. 13) and T wave inversion are observed.

Rice. 13. ECG with anterolateral myocardial infarction (acute stage). There are cicatricial changes in the posterior lower parts of the left ventricle

Sometimes there is an S-T shift without the presence of a pathological Q wave (small focal myocardial infarction). Signs of a heart attack:

Pathological Q wave in leads located above the infarction area;

An upward displacement (rise) of the ST segment relative to the isoline in the leads located above the infarction area;

Discordant displacement below the isoline of the ST segment in leads opposite to the infarction area;

Negative T wave in leads located over the infarction area.

As the disease progresses, the ECG changes. This relationship is explained by the staging of changes in heart attack.

There are four stages in the development of myocardial infarction:

The most acute stage (Fig. 14) lasts several hours. At this time, on the ECG in the corresponding leads, the ST segment rises sharply, merging with the T wave.

Rice. 14. The sequence of ECG changes in myocardial infarction: 1 - Q-infarction; 2 - not Q-infarction; A - the most acute stage; B - acute stage; B - subacute stage; D - cicatricial stage (postinfarction cardiosclerosis)

In the acute stage, a necrosis zone forms and a pathological Q wave appears. The R amplitude decreases, the ST segment remains elevated, the T wave becomes negative. The duration of the acute stage is on average about 1-2 weeks.

The subacute stage of myocardial infarction lasts for 1-3 months and is characterized by cicatricial organization of the necrosis focus. On the ECG at this time, there is a gradual return of the ST segment to the isoline, the Q wave decreases, and the R amplitude, on the contrary, increases.

The T wave remains negative.

The cicatricial stage can take several years. At this time, the organization of scar tissue occurs. On the ECG, the Q wave decreases or disappears completely, S-T is located on the isoline, negative T gradually becomes isoelectric, and then positive.

This staging is often called the natural dynamics of the ECG in myocardial infarction.

A heart attack can be localized in any part of the heart, but most often it occurs in the left ventricle.

Depending on the localization, infarction of the anterior lateral and posterior walls of the left ventricle is distinguished. Localization and prevalence of changes are revealed by analyzing ECG changes in the corresponding leads (Table 6).

Table 6. Localization of myocardial infarction

Great difficulties arise in the diagnosis of re-infarction, when new changes are superimposed on an already altered ECG. The dynamic control with the removal of the cardiogram at short intervals helps.

A typical heart attack is characterized by burning, severe chest pain that does not go away after taking nitroglycerin.

There are also atypical forms of heart attack:

Abdominal (pain in the heart and abdomen);

Asthmatic (cardiac pain and cardiac asthma or pulmonary edema);

Arrhythmic (cardiac pain and rhythm disturbances);

Collaptoid (cardiac pain and a sharp drop in blood pressure with profuse sweating);

Treating a heart attack is a daunting task. As a rule, it is more difficult, the greater the prevalence of the lesion. At the same time, according to the apt remark of one of the Russian zemstvo doctors, sometimes the treatment of an extremely severe heart attack goes unexpectedly smoothly, and sometimes an uncomplicated, unpretentious microinfarction makes the doctor sign his powerlessness.

Emergency care consists in relieving pain (for this, narcotic and other analgesics are used), also eliminating fears and psycho-emotional arousal with the help of sedatives, reducing the heart attack zone (using heparin), alternately eliminating other symptoms, depending on the degree of their danger.

After completion of inpatient treatment, patients who have suffered a heart attack are sent to a sanatorium for rehabilitation.

The final stage is long-term follow-up at the local polyclinic.

7.2.9. Electrolyte Disorders Syndromes

Certain ECG changes make it possible to judge the dynamics of the electrolyte content in the myocardium.

In fairness, it should be said that there is not always a clear correlation between the level of electrolytes in the blood and the content of electrolytes in the myocardium.

Nevertheless, electrolyte disturbances detected with the help of ECG serve as a significant help to the doctor in the process of a diagnostic search, as well as in choosing the correct treatment.

The most well studied ECG changes in violation of potassium metabolism, as well as calcium (Fig. 15).

Rice. 15. ECG diagnostics of electrolyte disturbances (AS Vorobiev, 2003): 1 - norm; 2 - hypokalemia; 3 - hyperkalemia; 4 - hypocalcemia; 5 - hypercalcemia

High pointed T wave;

Shortening of the Q-T interval;

Decrease in P.

With severe hyperkalemia, intraventricular conduction disturbances are observed.

Hyperkalemia occurs in diabetes (acidosis), chronic renal failure, severe injuries with crushing muscle tissue, adrenal insufficiency, and other diseases.

Decrease in the S-T segment downward;

Negative or biphasic T;

With severe hypokalemia, atrial and ventricular extrasystoles appear, and intraventricular conduction disorders.

Hypokalemia occurs with the loss of potassium salts in patients with severe vomiting, diarrhea, after prolonged use of diuretics, steroid hormones, and a number of endocrine diseases.

Treatment consists of replenishing the potassium deficiency in the body.

Shortening of the Q-T interval;

Shortening of the S-T segment;

Expansion of the ventricular complex;

Rhythm disturbances with a significant increase in calcium.

Hypercalcemia is observed with hyperparathyroidism, bone destruction by tumors, hypervitaminosis D, and excessive administration of potassium salts.

Increase in the duration of the Q-T interval;

Elongation of the S-T segment;

Decrease in T.

Hypocalcemia occurs with a decrease in the function of the parathyroid glands, in patients with chronic renal failure, with severe pancreatitis and hypovitaminosis D.

7.2.9.5. Glycosidic intoxication

Cardiac glycosides have long been successfully used in the treatment of heart failure. These funds are irreplaceable. Their reception helps to reduce heart rate (heart rate), more vigorous expulsion of blood during systole. As a result, hemodynamic indices improve and manifestations of circulatory insufficiency are reduced.

In case of an overdose of glycosides, characteristic ECG signs appear (Fig. 16), which, depending on the severity of intoxication, require either dose adjustment or drug withdrawal. Patients with glycosidic intoxication may feel nausea, vomiting, interruptions in the work of the heart.

Rice. 16. ECG in case of overdose of cardiac glycosides

Signs of glycosidic intoxication:

Shortening of electrical systole;

Decrease in the S-T segment downward;

Negative T wave;

Severe glycoside intoxication requires discontinuation of the drug and the appointment of potassium, lidocaine and beta-blockers.

A normal ECG consists mainly of P, Q, R, S, and T waves.
Between the individual teeth are the PQ, ST and QT segments, which are of clinical importance.
The R wave is always positive, and the Q and S waves are always negative. P and T waves are normally positive.
The spread of excitation in the ventricle on the ECG corresponds to the QRS complex.
When they talk about the restoration of myocardial excitability, they mean the ST segment and the T wave.

Normal ECG usually consists of P, Q, R, S, T and sometimes U waves. These designations were introduced by Einthoven, the founder of electrocardiography. He chose these lettering at random from the middle of the alphabet. The Q, R, S waves together form a QRS complex. However, depending on the lead in which the ECG is being recorded, the Q, R, or S waves may be missing. There are also PQ and QT intervals and PQ and ST segments that connect separate teeth and have a certain meaning.

Same part of the curve ECG can be called differently, for example, the atrial wave can be called a wave or a P wave. Q, R and S can be called a Q wave, an R wave and an S wave, and P, T and U can be called a P wave, a T wave and a U wave. for convenience, P, Q, R, S and T, with the exception of U, will be called teeth.

Positive prongs are located above the isoelectric line (zero line), and negative - below the isoelectric line. The P and T waves and the U wave are positive. These three waves are normally positive, but with pathology they can also be negative.

Q and S waves is always negative and the R wave is always positive. If a second R or S wave is registered, it is designated as R "and S".

QRS complex begins with a Q wave and lasts until the end of the S wave. This complex is usually split. In the QRS complex, high teeth are indicated by an uppercase letter, and low ones by a lowercase letter, for example, qrS or qRs.

The end of the QRS complex is indicated by point J.

For a beginner, the exact tooth recognition and segments is very important, so we dwell on them in detail. Each of the teeth and complexes is shown in a separate figure. For better understanding, next to the figures are the main features of these teeth and their clinical significance.

After describing the individual teeth and segments ECG and the corresponding explanations, we will get acquainted with the quantitative assessment of these electrocardiographic indicators, in particular the height, depth and width of the teeth and their main deviations from normal values.

P wave is normal

The P wave, which is a wave of atrial excitation, normally has a width of up to 0.11 s. The height of the P wave changes with age, but should normally not exceed 0.2 mV (2 mm). Usually, when these parameters of the P wave deviate from the norm, we are talking about atrial hypertrophy.

PQ interval is normal

The PQ interval, which characterizes the time of excitation to the ventricles, is normally 0.12 ms, but should not exceed 0.21 s. This interval is lengthened in AV blocks and shortened in WPW syndrome.

Q wave is normal

The Q wave in all assignments is narrow and its width does not exceed 0.04 s. The absolute value of its depth is not standardized, but the maximum is 1/4 of the corresponding R wave. Sometimes, for example, in obesity, a relatively deep Q wave is recorded in lead III.
A deep Q wave is primarily suspected of having an MI.

R wave normal

The R wave among all the ECG waves has the greatest amplitude. A high R wave is normally recorded in the left chest leads V5 and V6, but its height in these leads should not exceed 2.6 mV. A taller R wave indicates LV hypertrophy. Normally, the height of the R wave should increase with the transition from lead V5 to lead V6. With a sharp decrease in the height of the R wave, MI should be excluded.

Sometimes the R wave is split. In these cases, it is denoted by uppercase or lowercase letters (for example, the R or r wave). An additional R or r wave is denoted, as already mentioned, as R "or r" (for example, in lead V1.

S wave normal

The S wave in its depth is characterized by significant variability depending on the lead, the position of the patient's body and his age. With ventricular hypertrophy, the S wave is unusually deep, for example, with LV hypertrophy, in leads V1 and V2.

QRS complex is normal

The QRS complex corresponds to the spread of excitation through the ventricles and normally should not exceed 0.07-0.11 s. Expansion of the QRS complex (but not a decrease in its amplitude) is considered pathological. It is observed, first of all, with blockages of the legs of the PG.

J-point is normal

Point J corresponds to the point at which the QRS complex ends.

ST segment is normal

Normally, the ST segment is located on the isoelectric line, in any case, it does not deviate significantly from it. Only in leads V1 and V2 can it be above the isoelectric line. With a significant rise in the ST segment, a fresh MI should be ruled out, while a decrease in it indicates an ischemic heart disease.

The T wave is normal

The T wave is of clinical importance. It corresponds to the restoration of myocardial excitability and is usually positive. Its amplitude should not be less than 1/7 of the R wave in the corresponding lead (for example, in leads I, V5 and V6). With clearly negative T waves, combined with a decrease in the ST segment, MI and coronary heart disease should be excluded.

QT interval is normal

The width of the QT interval depends on the heart rate; it has no constant absolute values. Prolongation of the QT interval is observed with hypocalcemia and prolonged QT interval syndrome.

Barb- the rise of the curve above the isoline (positive tooth) or the descent of the curve from the isoline downward (negative tooth).

Interval- distance in seconds from the beginning of one wave to the beginning of another wave (excluding the QT interval).

Segment- is the distance of the isoline from the end of one tooth to the beginning of the adjacent tooth.

TOOTH R- is formed as a result of excitation of two atria. It begins to register immediately after the impulse leaves the sinus node. The amplitude of the P wave is usually greatest in the II century. lead. Normally, the duration of P is up to 0.1 s, the amplitude should not exceed 2.5 mm. In lead aVR, the wave is always negative.

PQ INTERVAL- from the beginning of the P wave to the beginning of the Q wave. It corresponds to the time of passage of excitation through the atria and the AV connection to the ventricular myocardium. Changes depending on the heart rate, on the age and body weight of the patient. Normally, the PQ interval is 0.12 - 0.18 (up to 0.2 s). Thus, the PQ interval includes the P wave and the PQ segment.

MAKRUZ INDEX : This is the ratio of the duration of the P wave to the duration of the PQ segment. Normally -1.1 - 1.6. This index helps in the diagnosis of atrial hypertrophy.

QRS complex- ventricular complex. This is usually the largest ECG deviation. The width of the QRS complex is normally 0.06 - 0.08 s and indicates the duration of intraventricular conduction of excitation. With age, the width of the QRS complex. The amplitude of the QRS complex waves usually varies. Normally, in at least one of the standard leads or in the limb leads, the amplitude of the QRS complex should exceed 5 mm, and in the chest leads - 8 mm. In any of the chest leads in adults, the amplitude of the QRS complex should not exceed 2.5 mm.

Q wave- the initial tooth of the QRS complex. it is recorded during excitation of the left half of the interventricular septum. Registration of the q wave of even a small amplitude in leads V1-V3 is a pathology. Normally, the width of the q wave should not exceed 0.03 s, and its amplitude in each lead should be less than 1/4 of the amplitude of the following R wave in this lead.

R wave- usually the main wave of the ECG. It is caused by excitation of the ventricles, and its amplitude in standard leads and in leads from the limbs depends on the position of the electrical axis of the heart. With the normal position of the electrical axis and RII> RI> RIII. The R wave may be missing in lead aVR. In the chest leads, the R wave should grow in amplitude from V1 to V4.

S wave- mainly due to the final excitation of the base of the left ventricle. This tooth may be absent normally, especially in the limb leads. In the chest leads, the largest amplitude of the S wave is in leads V1 and V2. The width S in any case should not exceed 0.03 s.

ST segment - corresponds to that period of the cardiac cycle when both ventricles are completely engulfed in excitement. The point where the QRS complex ends is designated as ST - connection, or point J. The ST segment directly passes into the T wave. The ST segment is normally located on the isoline, but it can be slightly raised or lowered. Normally, the ST segment can be located even 1.5 - 2 mm above the isoline. In healthy people, this is combined with a subsequent high positive T wave and has a concave shape. In cases where the ST segment is not located on the contour, its shape is described as concave, convex, or horizontal. The duration of this segment is not of great diagnostic value, and is usually not determined.

T wave... Recorded during ventricular repolarization. This is the most labile ECG wave. The T wave is normally usually positive. normally, the T wave is not serrated. The T wave is usually positive in those leads where the QRS complex is mainly represented by the R wave. In lead aVR T should always be negative. The duration of this wave is from 0.1 to 0.25 s, but it has little diagnostic value. The amplitude usually does not exceed 8 mm. Normally, TV1 is necessarily higher than TV6.

QT interval... This is the electrical systole of the ventricles. The QT interval is the time in seconds from the beginning of the QRS complex to the end of the T wave. Depends on gender, age and heart rate. Normally, the duration of the QT interval is 0.35 - 0.44 s. QT is a constant for a given heart rate separately for males and females.

There are special tables in which the standards for the electric systole of the ventricles for a given gender and rhythm frequency are presented.

U wave... A small positive wave, occasionally following the T wave, is best seen in the right chest leads, especially when the rhythm is infrequent. Clinically important is the presence of a pronounced U wave of increased amplitude (U> T), which almost always indicates hypokalemia. It should always be borne in mind that both healthy people. and with heart disease. the U wave may not be registered.

TR segment- corresponds to the diastole of the ventricles and atria, during which there is no electrical activity of the heart. Normally, this segment is located on the isoline.