Normal cardiogram of the heart. ECG decoding

An electrocardiograph using a sensor registers and records the parameters of the activity of the heart, which are printed on special paper. They look like vertical lines (teeth), the height and location of which relative to the axis of the heart are taken into account when deciphering the picture. If the ECG is normal, the impulses are clear, even lines that follow at a certain interval in a strict sequence.

The ECG study consists of the following indicators:

1. Prong R. Responsible for contractions of the left and right atria.
2. P-Q interval (R) - the distance between the R wave and the QRS complex (the beginning of the Q or R wave). Shows the duration of the passage of the impulse through the ventricles, the bundle of His and the atrioventricular node back to the ventricles.
3. The QRST complex is equal to the systole (moment of muscle contraction) of the ventricles. The excitation wave propagates at different intervals in different directions, forming Q, R, S teeth.
4. Q wave. Shows the beginning of the propagation of the impulse along the interventricular septum.
5. Wave S. Reflects the end of the distribution of excitation through the interventricular septum.
6. Wave R. Corresponds to the distribution of the impulse along the right and left ventricular myocardium.
7. Segment (R)ST. This is the path of the impulse from the end point of the S wave (in its absence, the R wave) to the beginning of the T.
8. Wave T. Shows the process of repolarization of the ventricular myocardium (rise of the gastric complex in the ST segment).

The video discusses the main elements that make up an electrocardiogram. Taken from the MEDFORS channel.

How to decipher a cardiogram

1. Age and gender.
2. Cells on paper consist of horizontal and vertical lines with large and small cells. Horizontal - responsible for the frequency (time), vertical - this is the voltage. The big square is equal to 25 small squares, each side of which is 1 mm and 0.04 seconds. A large square corresponds to a value of 5 mm and 0.2 seconds, and 1 cm of a vertical line is 1 mV of voltage.
3. The anatomical axis of the heart can be determined using the direction vector of the Q, R, S waves. Normally, the impulse should be conducted through the ventricles to the left and down at an angle of 30-70º.
4. The reading of the teeth depends on the distribution vector of the excitation wave on the axis. The amplitude differs in different leads, and part of the pattern may be missing. The upward direction from the isoline is considered positive, downward - negative.
5. The electrical axes of the leads Ι, ΙΙ, ΙΙΙ have a different location with respect to the axis of the heart, displaying, respectively, with different amplitudes. Leads AVR, AVF and AVL show the potential difference between the limbs (with a positive electrode) and the average potential of the other two (with a negative electrode). The AVR axis is directed from bottom to top and to the right, so most of the teeth have a negative amplitude. The AVL lead runs perpendicular to the electrical axis of the heart (EOS), so the total QRS complex is close to zero.

Interference and sawtooth oscillations (frequency up to 50 Hz) displayed in the picture may indicate the following:

• muscle tremor (small fluctuations with different amplitudes);
• chills;
• poor skin and electrode contact;
• failure of one or more wires;
• interference from household appliances.

Registration of cardiac impulses occurs with the help of electrodes that connect the electrocardiograph to the human limbs and chest.

The paths followed by discharges (leads) have the following designations:

• AVL (similar to the first);
• AVF (analogue of the third);
• AVR (mirror display of leads).

Designations of chest leads:

Teeth, segments and intervals

You can interpret the value of the indicators yourself using the ECG norms for each of them:

1. Prong R. Should be positive in leads Ι-ΙΙ and be biphasic in V1.
2. PQ interval. It is equal to the sum of the time of contraction of the atria and their conduction through the AV node.
3. Q wave. Must come before R and have a negative value. In compartments Ι, AVL, V5 and V6, it may be present at a length of not more than 2 mm. Its presence in the ΙΙΙ lead should be temporary and disappear after a deep breath.
4. QRS complex. It is calculated by cells: the normal width is 2-2.5 cells, the interval is 5, the amplitude is thoracic region- 10 small squares.
5. S-T segment. To determine the value, you need to count the number of cells from point J. Normally, they are 1.5 (60 ms).
6. T-wave. Must match the direction of the QRS. It has a negative value in leads: ΙΙΙ, AVL, V1 and a standard positive value - Ι, ΙΙ, V3-V6.
7. U wave. If this indicator is displayed on paper, it may occur in close proximity to the T wave and merge with it. Its height is 10% of T in compartments V2-V3 and indicates the presence of bradycardia.

How to calculate the heart rate

Calculation scheme heart rate looks like that:

1. Identify tall R waves on the ECG image.
2. Find the big squares between the vertices R is the heart rate.
3. Calculate by the formula: HR=300/number of squares.

For example, there are 5 squares between the vertices. HR=300/5=60 beats/min.

Photo gallery

Designations for deciphering the study The figure shows a normal sinus rhythm of the heart. Atrial fibrillation Method for determining heart rate Diagnosis of ischemic heart disease Myocardial infarction on electrocardiogram

What is an abnormal ECG

An abnormal electrocardiogram is a deviation of the results of the study from the norm. The doctor's job in this case is to determine the level of danger of anomalies in the transcript of the study.

Abnormal ECG results may indicate the presence of the following problems:

• the shape and size of the heart or one of its walls are markedly changed;
• electrolyte imbalance (calcium, potassium, magnesium);
• ischemia;
• heart attack;
• change in normal rhythm;
• side effect of the medications taken.

What does an ECG look like in normal and pathological conditions?

The parameters of the electrocardiogram in adult men and women are presented in the table and look like this:

What should be the cardiogram of a healthy person

Indications of a good cardiogram of an adult:

The video presents a comparison of the cardiogram of a healthy and sick person and gives the correct interpretation of the data obtained. Taken from the channel "Hypertension Life".

Indicators in adults

An example of a normal ECG in adults:

Indicators in children

Electrocardiogram parameters in children:

Rhythm disturbances during ECG interpretation

Violation of the heart rhythm can be observed in healthy people and is a variant of the norm. The most common types of arrhythmia and retreat of the conduction system. In the process of interpreting the data obtained, it is important to take into account all the indicators of the electrocardiogram, and not each separately.

Arrhythmias

A heart rhythm disorder can be:

1. sinus arrhythmia. Fluctuations in the amplitude of RR vary within 10%.
2. sinus bradycardia. PQ=12 seconds, heart rate less than 60 bpm.
3. Tachycardia. The heart rate in adolescents is more than 200 beats / min, in adults - more than 100-180. During ventricular tachycardia, the QRS rate is above 0.12 sec, sinus tachycardia is slightly higher than normal.
4. Extrasystoles. Extraordinary contraction of the heart is permissible in isolated cases.
5. Paroxysmal tachycardia. Increase in the number of heartbeats up to 220 per minute. During an attack, a fusion of QRS and P is observed. The range between R and P from the following contraction
6. Atrial fibrillation. Atrial contraction is equal to 350-700 per minute, ventricles - 100-180 per minute, P is absent, fluctuations along the isoline.
7. Atrial flutter. Atrial contraction is equal to 250-350 per minute, gastric contractions become less frequent. Sawtooth waves in branches ΙΙ-ΙΙΙ and V1.

EOS Position Deviation

A shift in the EOS vector can indicate health problems:

1. Deviation to the right is greater than 90º. In combination with the excess of the height S over R, it signals the pathologies of the right ventricle and the blockade of the bundle of His.
2. Deviation to the left by 30-90º. With a pathological ratio of the heights S and R - left ventricular hypertrophy, blockade of the bundle branch of His.

Deviations in the position of the EOS can signal the following diseases:

• heart attack;
• pulmonary edema;
• COPD (chronic obstructive pulmonary disease).

Conduction system disruption

The conclusion of the ECG may include the following pathologies of the conduction function:

• AV blockade of Ι degree - the distance between the P and Q waves exceeds the interval of 0.2 seconds, the path sequence looks like this - P-Q-R-S;
• AV blockade ΙΙ degree - PQ displace QRS (Mobitz type 1) or QRS drops out along the length of PQ (Mobitz type 2);
• complete AV block - the frequency of atrial contractions is greater than that of the ventricles, PP=RR, PQ length is different.

Selected heart diseases

A detailed interpretation of the electrocardiogram can show the following pathological conditions:

Video

In the video course "ECG is within the power of everyone" violations of the heart rhythm are considered. Taken from the MEDFORS channel.

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Almost every person who has undergone an electrocardiogram is interested in the meaning of different teeth and the terms written by the diagnostician. Although only a cardiologist can give a full interpretation of the ECG, everyone can easily figure out whether he has a good cardiogram of the heart or there are some deviations.

Indications for an ECG

A non-invasive study - an electrocardiogram - is performed in the following cases:

• The patient's complaints about high pressure, retrosternal pain and other symptoms indicating cardiac pathology;
• Deterioration of well-being of a patient with a previously diagnosed cardiovascular disease;
• Deviations in laboratory blood tests - high cholesterol, prothrombin;
• In the complex of preparation for the operation;
• Detection of endocrine pathology, diseases of the nervous system;
• After severe infections high risk heart complications;
• For prophylactic purposes in pregnant women;
• Examination of the health status of drivers, pilots, etc.

ECG decoding - numbers and Latin letters

A full-scale interpretation of the cardiogram of the heart includes an assessment of the heart rate, the work of the conduction system and the state of the myocardium. For this, the following leads are used (electrodes are installed in a certain order on the chest and limbs):

• Standard: I - left / right wrist on the hands, II - right wrist and ankle area on the left leg, III - left ankle and wrist.
• Reinforced: aVR - right wrist and combined left upper/lower limbs, aVL - left wrist and combined left ankle and wrist right hand, aVF - zone of the left ankle and the combined potential of both wrists.
• Thoracic (potential difference located on chest electrode with a suction cup and the combined potentials of all limbs): V1 - electrode in the IV intercostal space along the right border of the sternum, V2 - in the IV intercostal space to the left of the sternum, V3 - on the IV rib along the left parasternal line, V4 - V intercostal space along the left midclavicular line , V5 - V intercostal space along the anterior axillary line on the left, V6 - V intercostal space along the mid-axillary line on the left.

Additional pectorals - located symmetrically to the left pectoral with additional V7-9.

One cardiac cycle on the ECG is represented by the PQRST graph, which records electrical impulses in the heart:

• P wave - displays atrial excitation;
• QRS complex: Q wave - the initial phase of depolarization (excitation) of the ventricles, R wave - the actual process of ventricular excitation, S wave - the end of the depolarization process;
• wave T - characterizes the extinction of electrical impulses in the ventricles;
• ST segment - describes the complete recovery of the initial state of the myocardium.

When decoding ECG indicators, the height of the teeth and their location relative to the isoline, as well as the width of the intervals between them, matters.

Sometimes a U impulse is registered behind the T wave, indicating the parameters of the electric charge carried away with the blood.

Interpretation of ECG indicators - the norm in adults

On the electrocardiogram, the width (horizontal distance) of the teeth - the duration of the period of excitation of relaxation - is measured in seconds, the height in leads I-III - the amplitude of the electrical impulse - in mm. A normal cardiogram in an adult looks like this:

• The heart rate is normal heart rate within 60-100/min. The distance from the tops of adjacent R waves is measured.
• EOS - the electric axis of the heart is the direction of the total angle of the electric force vector. The normal indicator is 40-70º. Deviations indicate the rotation of the heart around its own axis.
• P wave - positive (directed upwards), negative only in lead aVR. Width (excitation duration) - 0.7 - 0.11 s, vertical size - 0.5 - 2.0 mm.
• Interval PQ - horizontal distance 0.12 - 0.20 s.
• The Q wave is negative (below the isoline). The duration is 0.03 s, the negative value of the height is 0.36 - 0.61 mm (equal to ¼ of the vertical dimension of the R wave).
• The R wave is positive. Its height is important - 5.5 -11.5 mm.
• Tooth S - negative height 1.5-1.7 mm.
• QRS complex - horizontal distance 0.6 - 0.12 s, total amplitude 0 - 3 mm.
• The T wave is asymmetric. Positive height 1.2 - 3.0 mm (equal to 1/8 - 2/3 of the R wave, negative in aVR lead), duration 0.12 - 0.18 s (more than the duration of the QRS complex).
• ST segment - runs at the level of the isoline, length 0.5 -1.0 s.
• U wave - height indicator 2.5 mm, duration 0.25 s.

Abbreviated results of ECG decoding in adults and the norm in the table:

In the usual conduct of the study (recording speed - 50 mm / s), the decoding of the ECG in adults is performed according to the following calculations: 1 mm on paper when calculating the duration of the intervals corresponds to 0.02 sec.

A positive P wave (standard leads) followed by a normal QRS complex indicates normal sinus rhythm.

ECG norm in children, decoding

Cardiogram parameters in children are somewhat different from those in adults and vary depending on age. Decryption ECG of the heart in children, the norm:

• Heart rate: newborns - 140 - 160, by 1 year - 120 - 125, by 3 years - 105 -110, by 10 years - 80 - 85, after 12 years - 70 - 75 per minute;
• EOS - corresponds to adult indicators;
• sinus rhythm;
• tooth P - does not exceed 0.1 mm in height;
• the length of the QRS complex (often not particularly informative in diagnosis) - 0.6 - 0.1 s;
• PQ interval - less than or equal to 0.2 s;
• Q wave - non-permanent parameters, negative values ​​in lead III are acceptable;
• P wave - always above the isoline (positive), the height in one lead may fluctuate;
• wave S - negative indicators of non-constant value;
• QT - no more than 0.4 s;
• the duration of the QRS and the T wave are equal, they are 0.35 - 0.40.

An example of an ECG with arrhythmia

According to deviations in the cardiogram, a qualified cardiologist can not only diagnose the nature of a heart disease, but also fix the location of the pathological focus.

Arrhythmias

Distinguish the following violations of cardiac rhythm:

1. Sinus arrhythmia - the length of the RR intervals fluctuates with a difference of up to 10%. It is not considered a pathology in children and young people.
2. Sinus bradycardia is a pathological decrease in the frequency of contractions to 60 per minute or less. The P wave is normal, PQ from 12 s.
3. Tachycardia - heart rate 100 - 180 per minute. In adolescents - up to 200 per minute. The rhythm is right. With sinus tachycardia, the P wave is slightly higher than normal, with ventricular tachycardia - QRS - length indicator above 0.12 s.
4. Extrasystoles - extraordinary contractions of the heart. Single on a conventional ECG (on a daily Holter - no more than 200 per day) are considered functional and do not require treatment.
5. Paroxysmal tachycardia is a paroxysmal (several minutes or days) increase in the frequency of heart beats up to 150-220 per minute. It is characteristic (only during an attack) that the P wave merges with the QRS. The distance from the R wave to the P height from the next contraction is less than 0.09 s.
6. Atrial fibrillation - irregular atrial contraction with a frequency of 350-700 per minute, and ventricles - 100-180 per minute. There is no P wave, fine-coarse-wave oscillations along the entire isoline.
7. Atrial flutter - up to 250-350 per minute of atrial contractions and regular reduced ventricular contractions. The rhythm can be correct, on the ECG there are sawtooth atrial waves, especially pronounced in standard leads II - III and chest V1.

EOS Position Deviation

A change in the total EOS vector to the right (more than 90º), a higher S wave height compared to the R wave indicate a pathology of the right ventricle and blockade of the His bundle.

When the EOS is shifted to the left (30-90º) and the pathological ratio of the height of the S and R teeth is diagnosed, left ventricular hypertrophy, blockade of the leg of the n. His. EOS deviation indicates a heart attack, pulmonary edema, COPD, but it also happens in the norm.

Conduction system disruption

The following pathologies are most often recorded:

• 1 degree atrioventricular (AV-) block - PQ distance more than 0.20 s. After each R, a QRS follows naturally;
• Atrioventricular blockade 2 tbsp. - a gradually lengthening PQ during the ECG sometimes displaces the QRS complex (Mobitz 1 deviation) or a complete prolapse of the QRS is recorded against the background of a PQ of equal length (Mobitz 2);
• Complete blockade of the AV node - atrial HR is higher than the ventricular FR. PP and RR are the same, PQ are different lengths.

Selected heart diseases

The results of the ECG decoding can provide information not only about what happened heart disease, but also pathologies of other organs:

1. Cardiomyopathy - atrial hypertrophy (usually left), low-amplitude teeth, partial blockade of p. Gis, atrial fibrillation or extrasystoles.
2. Mitral stenosis - the left atrium and right ventricle are enlarged, the EOS is rejected to the right, often atrial fibrillation.
3. Mitral valve prolapse - flattened/negative T wave, some QT prolongation, depressive ST segment. Various rhythm disturbances are possible.
4. Chronic obstruction of the lungs - EOS to the right of the norm, low-amplitude teeth, AV blockade.
5. CNS damage (including subarachnoid hemorrhage) - pathological Q, wide and high-amplitude (negative or positive) T wave, pronounced U, long QT duration of rhythm disturbance.
6. Hypothyroidism - long PQ, low QRS, flat T wave, bradycardia.

Quite often, an ECG is performed to diagnose myocardial infarction. At the same time, each of its stages corresponds to characteristic changes in the cardiogram:

• ischemic stage - peaked T with a sharp apex is fixed 30 minutes before the onset of necrosis of the heart muscle;
• stage of damage (changes are recorded in the first hours up to 3 days) - ST in the form of a dome above the isoline merges with the T wave, shallow Q and high R;
• acute stage (1-3 weeks) - the worst cardiogram of the heart during a heart attack - the preservation of domed ST and the transition of the T wave to negative values, a decrease in R height, pathological Q;
• subacute stage (up to 3 months) - comparison of ST with isoline, preservation of pathological Q and T;
• scarring stage (several years) - pathological Q, negative R, smoothed T wave gradually comes to normal.

You should not sound the alarm if you found pathological changes in the ECG handed out. It should be remembered that some deviations from the norm occur in healthy people.

If the electrocardiogram revealed any pathological processes in the heart, you will definitely be assigned a consultation with a qualified cardiologist.

How to decipher the cardiogram of the heart

An electrocardiographic study is quite simple and effective method diagnostics, used by cardiologists around the world to study the activity of the heart muscle. The results of the procedure in the form of graphs and digital symbols, as a rule, are transferred to specialists for further data analysis. However, in the case of, for example, the absence of the right doctor, the patient has a desire to independently decipher the indicators of his heart.
Preliminary interpretation of the ECG requires knowledge of special basic data, which, due to their specificity, are not subject to everyone. In order to make correct calculations of the ECG of the heart for a person who is not related to medicine, it is necessary to familiarize yourself with the basic principles of processing, which are combined for convenience into the appropriate blocks.

Familiarization with the basic elements of a cardiogram

You should know that the interpretation of the ECG is carried out thanks to elementary, logical rules that can be understood even by an ordinary layman. For a more pleasant and calm perception of them, it is recommended to start familiarizing yourself first with the simplest principles of decoding, gradually moving to a more complex level of knowledge.

Ribbon layout

The paper, which reflects data on the functioning of the heart muscle, is a wide ribbon of a soft pink hue with a clear “square” marking. The larger quadrilaterals are formed from 25 small cells, and each of them, in turn, equates to 1 mm. If a large cell is filled with only 16 dots, for convenience, you can draw parallel lines along them and follow similar instructions.
The horizontals of the cells indicate the duration of the heartbeat (sec), and the verticals indicate the voltage of individual ECG segments (mV). 1 mm is 1 second of time (in width) and 1 mV of voltage (in height)! This axiom must be kept in mind throughout the entire period of data analysis, later its importance will become obvious to everyone.

teeth and segments

Before moving on to the names of specific departments of the gear graph, it is worth familiarizing yourself with the activity of the heart itself. The muscular organ consists of 4 compartments: the 2 upper ones are called the atria, the 2 lower ones are called the ventricles. Between the ventricle and the atrium in each half of the heart there is a valve - a leaflet responsible for accompanying blood flow in one direction: from top to bottom.
This activity is achieved due to electrical impulses that move through the heart according to the "biological timetable". They are sent to specific segments of the hollow organ using a system of bundles and nodes, which are miniature muscle fibers.
The birth of the impulse occurs in the upper part of the right ventricle - the sinus node. Further, the signal passes into the left ventricle and excitation of the upper parts of the heart is observed, which is recorded by the P wave on the ECG: it looks like a gentle inverted cup.
After the electric charge reaches the atrioventricular node (or AV node), located almost at the junction of all 4 pockets of the heart muscle, a small “point” appears on the cardiogram, pointing down - this is the Q wave. Just below the AV node there is the following item the purpose of the impulse is the bundle of His, which is fixed by the highest tooth R among others, which can be represented as a peak or mountain.
Having overcome half the way, an important signal rushes to the lower part of the heart, through the so-called legs of the bundle of His, outwardly resembling the long tentacles of an octopus that hug the ventricles. The conduction of the impulse along the branched processes of the bundle is reflected in the S wave - a shallow groove at the right foot of R. When the impulse spreads to the ventricles along the legs of the bundle of His, they contract. The last bumpy T wave marks the recovery (rest) of the heart before the next cycle.
In front of the 5 main teeth on the ECG, you can see a rectangular protrusion, you should not be afraid of it, since it is a calibration or control signal. Between the teeth there are horizontally directed sections - segments, for example, S-T (from S to T) or P-Q (from P to Q). To independently make an indicative diagnosis, you will need to remember such a concept as the QRS complex - the combination of the Q, R and S teeth, which registers the work of the ventricles.
The teeth that rise above the isometric line are called positive, and those that are located below them are called negative. Therefore, all 5 teeth alternate one after the other: P (positive), Q (negative), R (positive), S (negative) and T (positive).
Often you can hear the question from people: why are all the ECG graphs different from each other? The answer is relatively simple. Each of the curved lines on the tape reflects the heart readings obtained from 10-12 colored electrodes, which are installed on the limbs and in the chest area. They read data on the heart impulse, located at different distances from the muscle pump, because the graphics on the thermal tape are often different from each other.

Normal indicators of the cardiogram

Now that it has become clear how to decipher the cardiogram of the heart, one should proceed to the direct diagnosis of normal indications. But before getting acquainted with them, it is necessary to evaluate the ECG recording speed (50 mm / s or 25 mm / s), which, as a rule, is automatically printed on paper tape. Then, starting from the result, you can view the norms for the duration of the teeth and segments that are listed in the table (calculations can be carried out using a ruler or checkered markings on the tape):

How to read an ECG? How to decipher an electrocardiogram yourself? What does the ECG show

An electrocardiograph (ECG) is a device that allows you to evaluate cardiac activity, as well as to diagnose the state of this organ. During the examination, the doctor receives data in the form of a curve. How to read an ECG trace? What are the types of teeth? What changes are visible on the ECG? Why do doctors need this diagnostic method? What does the ECG show? These are far from all the questions that interest people who are faced with electrocardiography. First you need to know how the heart works.

The human heart consists of two atria and two ventricles. The left side of the heart is more developed than the right, as it has a greater load. It is this ventricle that most often suffers. Despite the difference in size, both sides of the heart must work stably, harmoniously.

Learning to read an electrocardiogram on your own

How to read an ECG correctly? This is not as difficult to do as it might seem at first glance. First you need to look at the cardiogram. It is printed on special paper with cells, and two types of cells are clearly visible: large and small.
The conclusion of the ECG is read by these cells. What do ECG-waves, cells show? These are the main parameters of the cardiogram. Let's try to learn how to read an ECG from scratch.

Meaning of cells (cells)

There are two types of cells on the paper for printing the examination result: large and small. All of them consist of vertical and horizontal guides. Vertical is voltage, and horizontal is time.

Large squares consist of 25 small cells. Each small cell is 1 mm and corresponds to 0.04 seconds in the horizontal direction. Large squares are 5 mm and 0.2 seconds. In the vertical direction, a centimeter of the strip is equal to 1 mV of voltage.
To read the conclusion of the ECG, you need to know what teeth are there and what they mean.
There are five teeth in total. Each of them on the graph displays the work of the heart.

All ECG teeth have their own reading characteristics.

All teeth of the electrocardiogram are of some importance for the correct diagnosis.
The very first tooth of the graph is called P. It denotes the time between heartbeats. To measure it, it is best to highlight the beginning and end of the tooth with vertical lines, and then count the number of small cells. Normally, the P wave should be between 0.12 and 2 seconds.
However, measuring this indicator in only one area will not give accurate results. To make sure that the heartbeat is even, it is necessary to determine the interval of the P wave in all areas of the electrocardiogram.
Knowing how to read an ECG the easy way, you can understand if there are pathologies of the heart. The next important tooth on the graph is R. It is easy to find - this is the highest peak on the graph. This will be the positive wave. Its highest part is marked on the R cardiogram, and its lower parts are Q and S.
The QRS complex is called the ventricular or sinus complex. In a healthy person, the sinus rhythm on the ECG is narrow, high. The ECG R waves are clearly visible in the figure, they are the highest:

Between these peaks, the number of large squares indicates the heart rate (HR). This indicator is calculated using the following formula:
300/number of large squares = heart rate.

For example, there are four full squares between the peaks, then the calculation will look like this:
300/4=75 heart beats per minute.
Sometimes on the cardiogram there is an elongation of the QRS complex for more than 0.12 s, which indicates a blockade of the bundle of His.

PQ wave interval

PQ is the interval from the P wave to Q. It corresponds to the time of excitation through the atria to the ventricular myocardium. The norm of the PQ interval at different ages is different. Usually it is 0.12-0.2 s.
With age, the interval increases. So, in children under 15 years of age, PQ can reach 0.16 s. At the age of 15 to 18 years, PQ increases to 0.18 s. In adults, this indicator is equal to a fifth of a second (0.2).
When the interval is extended to 0.22 s, they speak of bradycardia.

Interval between QT waves

To know how to read an ECG correctly, you need to understand the intervals. After determining the teeth, proceed to the calculation of the QT interval. Normally, it is 400-450 ms.
If this complex is longer, then we can assume coronary artery disease, myocarditis or rheumatism. With a shortened type, hypercalcemia may occur.

ST interval

Normally, this indicator is located at the level of the midline, but may be two cells higher than it. This segment shows the process of restoration of depolarization of the heart muscle.
In rare cases, the indicator can rise three cells above the midline.
The decoding of the cardiogram normally should look like this:

• The Q and S segments should always be below the midline, i.e. negative.
• The R and T waves should normally be located above the midline, i.e., they will be positive.
• The QRS complex should be no wider than 0.12 s.
• Heart rate should be between 60 and 85 beats per minute.
• There should be sinus rhythm on the ECG.
• The R must be above the S wave.

ECG in pathologies: sinus arrhythmia

And how to read an ECG for various pathologies? One of the most common heart diseases is sinus rhythm. It can be pathological and physiological. The latter type is usually diagnosed in people involved in sports, with neuroses.
With sinus arrhythmia, the cardiogram has the following form: sinus rhythms are preserved, fluctuations in the R-R intervals are observed, but the graph is even during breath holding.
With pathological arrhythmia, the preservation of the sinus impulse is observed constantly, regardless of breath holding, while wave-like changes are observed at all R-R intervals.

The manifestation of a heart attack on the ECG

When a myocardial infarction occurs, the changes on the ECG are pronounced. Signs of pathology are:

• increase in heart rate;
• the ST segment is elevated;
• there is a fairly persistent depression in the ST leads;
• the QRS complex increases.

In case of a heart attack, the cardiogram is the main means of recognizing the zones of necrosis of the heart muscle. With its help, you can determine the depth of damage to the organ.
In a heart attack, the ST segment is elevated on the graph, and the R wave will be lowered, giving the ST a cat-like shape. Sometimes with pathology, changes in the Q wave can be observed.
If ischemia occurs on the ECG, you can see in which part it is located.

• Location of ischemia at the anterior wall of the left ventricle. Diagnosed with symmetrical peaked T-teeth.
• Location near the epicardium of the left ventricle. The T-tooth is pointed, symmetrical, directed downwards.
• Transmural type of left ventricular ischemia. T pointed, negative, symmetrical.
• Ischemia in the myocardium of the left ventricle. T is smoothed, slightly raised up.
• Damage to the heart by coronary disease is displayed by the state of the T wave.

Changes in the ventricles

An ECG shows changes in the ventricles. Most often they appear in the left ventricle. This type of cardiogram occurs in people with prolonged additional stress, such as obesity. With this pathology, the electric axis deviates to the left, against which the S wave becomes higher than R.

Holter Method

But how to learn to read an ECG, if it is not always clear which teeth are located and how? In such cases, continuous registration of the cardiogram using a mobile device is prescribed. He constantly records ECG data on a special tape.

This method of examination is necessary in cases where the classical ECG fails to detect pathologies. During the diagnosis of Holter, a detailed diary is necessarily kept, where the patient records all his actions: sleep, walks, sensations during activity, all activity, rest, symptoms of the disease.
Typically, data registration occurs within a day. However, there are cases when it is necessary to take readings up to three days.

ECG decoding schemes

According to the duration of the R-R cycle, they speak about the regularity and norm of the heart rhythm. When evaluating the work of the heart, not one R-R interval is evaluated, but all. Normally, deviations within 10% of the norm are allowed. In other cases, an irregular (pathological) rhythm is determined.
To establish the pathology, the QRS complex and a certain period of time are taken. It counts how many times the segment is repeated. Then the same period of time is taken, but further on the cardiogram, it is again calculated. If at equal time intervals the number of QRS is the same, then this is the norm. At different amounts, pathology is assumed, while focusing on the P waves. They should be positive and stand in front of the QRS complex. Throughout the graph, the shape of P should be the same. This option indicates sinus rhythm of the heart.
With atrial rhythms, the P wave is negative. Behind it is the QRS segment. In some people, the P wave on the ECG may be absent, completely merging with the QRS, which indicates the pathology of the atria and ventricles, which the impulse reaches at the same time.
The ventricular rhythm is shown on the electrocardiogram as a deformed and extended QRS. In this case, the connection between P and QRS is not visible. There are large distances between the R waves.

cardiac conduction

ECG determines cardiac conduction. The P wave determines the atrial impulse, normally this indicator should be 0.1 s. The P-QRS interval displays the overall atrial conduction velocity. The norm of this indicator should be in the range of 0.12 to 0.2 s.
The QRS segment shows conduction through the ventricles, the limit is considered to be the norm from 0.08 to 0.09 s. With an increase in intervals, cardiac conduction slows down.
What the ECG shows, patients do not need to know. This should be dealt with by a specialist. Only a doctor can correctly decipher the cardiogram and make the correct diagnosis, taking into account the degree of deformation of each individual tooth, segment.
It is not always possible to read the result of an electrocardiogram on your own due to lack of experience and fuzzy teeth, segments, intervals, as well as paper features.

Deciphering the ECG in adults: what do the indicators mean

An electrocardiogram is a diagnostic method that allows you to determine the functional state of the most important organ human body- hearts. Most people at least once in their lives have dealt with a similar procedure. But having received the ECG result in hand, not every person, unless he has a medical education, will be able to understand the terminology used in cardiograms.

What is cardiography

The essence of cardiography is the study of electrical currents that occur during the work of the heart muscle. The advantage of this method is its relative simplicity and availability. Strictly speaking, it is customary to call a cardiogram the result of measuring the electrical parameters of the heart, displayed in the form of a time graph.
Creation of electrocardiography in its modern form is associated with the name of the Dutch physiologist of the early 20th century, Willem Einthoven, who developed the basic methods of ECG and the terminology used by doctors to this day.
Thanks to the cardiogram, it is possible to obtain the following information about the heart muscle:

• Heart rate,
• Physical state of the heart
• The presence of arrhythmias
• The presence of acute or chronic damage to the myocardium,
• The presence of metabolic disorders in the heart muscle,
• The presence of violations of electrical conductivity,
• The position of the electrical axis of the heart.

Also, the electrocardiogram of the heart can be used to obtain information about some vascular diseases that are not related to the heart.
An ECG is usually performed in the following cases:

• Feeling an abnormal heartbeat;
• Attacks of shortness of breath, sudden weakness, fainting;
• Heartache;
• Murmurs in the heart;
• Deterioration of the condition of patients with cardiovascular diseases;
• Passage of medical examinations;
• Medical examination of people over 45 years old;
• Inspection before the operation.

• pregnancy;
• Endocrine pathologies;
• Nervous diseases;
• Changes in blood counts, especially with an increase in cholesterol;
• Over 40 years of age (once a year).

Where can I get a cardiogram?

If you suspect that your heart is not all right, then you can contact a general practitioner or cardiologist to give you a referral for an ECG. Also, on a paid basis, a cardiogram can be done at any clinic or hospital.

Procedure procedure

The ECG recording is usually performed in the supine position. To take a cardiogram, a stationary or portable device is used - an electrocardiograph. Stationary devices are installed in medical institutions, and portable ones are used by teams emergency care. The device receives information about the electrical potentials on the surface of the skin. For this, electrodes are used, attached to the chest and limbs.
These electrodes are called leads. On the chest and limbs, 6 leads are usually installed. The chest leads are designated V1-V6, the leads on the limbs are called the main (I, II, III) and enhanced (aVL, aVR, aVF). All leads give a slightly different pattern of fluctuations, however, summing up the information from all the electrodes, you can find out the details of the work of the heart as a whole. Sometimes additional leads (D, A, I) are used.
Usually, the cardiogram is displayed as a graph on paper containing millimeter markings. Each lead-electrode has its own schedule. The standard belt speed is 5 cm/s, other speeds can be applied. In the cardiogram displayed on the tape, the main parameters, norm indicators and the conclusion generated automatically can also be indicated. Also, data can be recorded in memory and on electronic media.
After the procedure, it is usually required to decipher the cardiogram by an experienced cardiologist.

Holter monitoring

In addition to stationary devices, there are also portable devices for daily (Holter) monitoring. They are attached to the patient's body along with electrodes and record all the information received over a long period of time (usually within a day). This method gives much more complete information about the processes in the heart compared to a conventional cardiogram. So, for example, when taking a cardiogram in stationary conditions, the patient must be at rest. Meanwhile, some deviations from the norm can manifest themselves during physical exertion, in sleep, etc. Holter monitoring provides information about such phenomena.

Other types of procedures

There are several other methods of carrying out the procedure. For example, this is monitoring with physical activity. Abnormalities are usually more pronounced on the exercise ECG. The most common way to provide the body with the necessary physical activity is a treadmill. This method is useful in cases where pathologies can manifest themselves only in case of increased work of the heart, for example, if coronary disease is suspected.
With phonocardiography, not only the electrical potentials of the heart are recorded, but also the sounds that arise in the heart. The procedure is prescribed when it is necessary to clarify the occurrence of heart murmurs. This method is often used for suspected heart defects.

The patient must be calm during the procedure. Between physical activity and the procedure must pass a certain period of time. It is also not recommended to undergo the procedure after eating, drinking alcohol, caffeinated drinks or cigarettes.
Causes that can affect the ECG:

• Times of Day,
• electromagnetic background,
• Physical exercise,
• food intake,
• The position of the electrodes.

Prong types

First, let's talk a little about how the heart works. It has 4 chambers - two atria and two ventricles (left and right). The electrical impulse, due to which it is reduced, is formed, as a rule, in the upper part of the myocardium - in the sinus pacemaker - the nerve sinoatrial (sinus) node. The impulse propagates down the heart, first affecting the atria and causing them to contract, then it passes through the atrioventricular ganglion and another ganglion - the bundle of His, and reaches the ventricles. The main burden of pumping blood is taken by the ventricles, especially the left one, which is involved in big circle circulation. This stage is called contraction of the heart or systole.
After the contraction of all parts of the heart, the time comes for their relaxation - diastole. Then the cycle repeats again and again - this process is called the heartbeat.
The state of the heart, in which there is no change in the propagation of impulses, is reflected on the ECG in the form of a straight horizontal line, called the isoline. The deviation of the graph from the isoline is called a tooth.
One heartbeat on an ECG contains six teeth: P, Q, R, S, T, U. The teeth can be directed both up and down. In the first case, they are considered positive, in the second - negative. The Q and S waves are always positive, and the R wave is always negative.

The teeth reflect the different phases of the contraction of the heart. P reflects the moment of contraction and relaxation of the atria, R - excitation of the ventricles, T - relaxation of the ventricles. Special designations are also used for segments (gaps between adjacent teeth) and intervals (sections of the graph, including segments and teeth), for example, PQ, QRST.
Correspondence of the stages of heart contraction and some elements of cardiograms:

• P - atrial contraction;
• PQ - horizontal line, the transition of the discharge from the atria through the atrioventricular node to the ventricles. The Q wave may be absent normally;
• QRS - ventricular complex, the element most often used in diagnostics;
• R - excitation of the ventricles;
• S - relaxation of the myocardium;
• T - relaxation of the ventricles;
• ST - horizontal line, myocardial recovery;
• U - may be absent in the norm. The reasons for the appearance of a tooth have not been unequivocally elucidated, however, the tooth is valuable for diagnosing certain diseases.

Below are some ECG abnormalities and their possible explanations. This information, of course, does not negate the fact that it is more expedient to entrust the decoding to a professional cardiologist who knows better all the nuances of deviations from the norms and related pathologies.

How to decipher the ECG analysis, the norm and deviations, pathologies and the principle of diagnosis

Cardiovascular disease is the most common cause of death in post-industrial societies. Timely diagnosis and therapy of the organs of the cardiovascular system helps to reduce the risk of developing heart pathologies among the population.
An electrocardiogram (ECG) is one of the simplest and most informative methods for studying cardiac activity. The ECG records the electrical activity of the heart muscle and displays the information in the form of waves on a paper tape.
ECG results are used in cardiology to diagnose various diseases. It is not recommended to decipher the ECG of the heart on your own, it is better to consult a specialist. However, to get a general idea, it is worth knowing what the cardiogram shows.

Indications for an ECG

In clinical practice, there are several indications for electrocardiography:

• severe chest pain;
• constant fainting;
• dyspnea;
• intolerance to physical activity;
• dizziness;
• murmurs in the heart.

With a planned examination, the ECG is a mandatory diagnostic method. There may be other indications, which are determined by the attending physician. If you have any other disturbing symptoms, consult a doctor immediately to identify their cause.

How to decipher the cardiogram of the heart?

A strict ECG decoding plan consists of analyzing the resulting graph. In practice, only the total vector of the QRS complex is used. The work of the heart muscle is presented as a continuous line with marks and alphanumeric designations. Any person can decipher the ECG with some preparation, but only a doctor can make the correct diagnosis. ECG analysis requires knowledge of algebra, geometry and understanding of letter symbols.
Reading the ECG and making conclusions is necessary not only for cardiologists, but also for general practitioners (for example, paramedics). Timely interpretation of the ECG allows you to provide effective first aid to the victims.
ECG indicators to which you need to pay attention when deciphering the results:

• intervals;
• segments;
• teeth.

There are strict indicators of the norm on the ECG, and any deviation is already a sign of abnormalities in the functioning of the heart muscle. Pathology can be excluded only by a qualified specialist - a cardiologist.

ECG analysis

ECG records cardiac activity in twelve leads: 6 limb leads (aVR, aVL, aVF, I, II, III) and six chest leads (V1-V6). The P wave represents the process of atrial excitation and relaxation. The Q,S waves show the phase of depolarization of the interventricular septum. R is a wave indicating depolarization of the lower chambers of the heart, and a T wave is relaxation of the myocardium.

Electrocardiogram analysis
The QRS complex shows the time of depolarization of the ventricles. The time it takes for an electrical impulse to travel from the SA node to the AV node is measured by the PR interval.
Computers built into most ECG devices are capable of measuring the time it takes for an electrical impulse to travel from the SA node to the ventricles. These measurements can help your doctor evaluate your heart rate and j,yfhe;bnm some types of heart block.
Computer programs can also interpret ECG results. And as artificial intelligence and programming improves, they are often more accurate. However, the interpretation of the ECG has a lot of subtleties, so the human factor is still an important part of the assessment.
In the electrocardiogram, there may be deviations from the norm that do not affect the quality of life of the patient. However, there are standards for normal cardiac performance that are accepted by the international cardiology community.
Based on these standards, a normal electrocardiogram in a healthy person is as follows:

• RR interval - 0.6-1.2 seconds;
• P-wave - 80 milliseconds;
• PR interval - 120-200 milliseconds;
• segment PR - 50-120 milliseconds;
• QRS complex - 80-100 milliseconds;
• J-prong: absent;
• ST segment - 80-120 milliseconds;
• T-prong - 160 milliseconds;
• ST interval - 320 milliseconds;
• the QT interval is 420 milliseconds or less if the heart rate is sixty beats per minute.
• ind. juice – 17.3.

Normal ECG

Pathological ECG parameters

The ECG in normal and pathological conditions is significantly different. Therefore, it is necessary to carefully approach the decoding of the cardiogram of the heart.

QRS complex

Any abnormality in the electrical system of the heart causes a lengthening of the QRS complex. The ventricles have more muscle mass than the atria, so the QRS complex is significantly longer than the P wave. The duration, amplitude, and morphology of the QRS complex are useful in detecting cardiac arrhythmias, conduction abnormalities, ventricular hypertrophy, myocardial infarction, electrolyte abnormalities, and other disease states.

Q, R, T, P, U teeth

Pathological Q waves occur when an electrical signal travels through damaged heart muscle. They are considered markers of a previous myocardial infarction.
R-wave depression is usually also associated with myocardial infarction, but it can also be caused by left bundle branch block, WPW syndrome, or hypertrophy of the lower chambers of the heart muscle.

Table of ECG indicators is normal
T-wave inversion is always considered abnormal on the ECG tape. Such a wave may be a sign of coronary ischemia, Wellens' syndrome, hypertrophy of the lower cardiac chambers, or a CNS disorder.
An enlarged P wave may indicate hypokalemia and right atrial hypertrophy. Conversely, a reduced P wave may indicate hyperkalemia.
U-waves are most commonly seen with hypokalemia but may also be present with hypercalcemia, thyrotoxicosis, or epinephrine, class 1A and class 3 antiarrhythmic drugs. They are not uncommon in congenital long QT syndrome and intracranial hemorrhage.
An inverted U-wave may indicate pathological changes in the myocardium. Another U-wave can sometimes be seen on the ECG in athletes.

QT, ST, PR intervals

QTc prolongation causes premature action potentials during the late phases of depolarization. This increases the risk of developing ventricular arrhythmias or fatal ventricular fibrillation. Higher rates of QTc elongation are observed in women, older patients, hypertensive patients and in people of small stature.
The most common causes of QT prolongation are hypertension and certain medications. The calculation of the duration of the interval is carried out according to the Bazett formula. With this sign, the interpretation of the electrocardiogram should be performed taking into account the history of the disease. Such a measure is necessary to exclude hereditary influence.
ST interval depression may indicate coronary artery ischemia, transmural myocardial infarction, or hypokalemia.

Characteristics of all indicators of an electrocardiographic study
A prolonged PR interval (greater than 200 ms) may indicate first-degree heart block. Lengthening may be associated with hypokalemia, acute rheumatic fever, or Lyme disease. A short PR interval (less than 120 ms) may be associated with Wolff-Parkinson-White syndrome or Lown-Ganong-Levine syndrome. PR segment depression may indicate atrial injury or pericarditis.

Examples of heart rhythm description and ECG interpretation

Normal sinus rhythm

Sinus rhythm is any heart rhythm in which the excitation of the heart muscle starts from the sinus node. It is characterized by correctly oriented P waves on the ECG. By convention, the term "normal sinus rhythm" includes not only normal P waves, but all other ECG measurements.
ECG norm in adults:

Sinus bradycardia

A heart rate less than 55 in sinus rhythm is called bradycardia. ECG decoding in adults should take into account all parameters: sports, smoking, medical history. Because in some cases, bradycardia is a variant of the norm, especially in athletes.
Pathological bradycardia occurs with weak sinus node syndrome and is recorded on the ECG at any time of the day. This condition is accompanied by constant fainting, pallor and hyperhidrosis. In extreme cases, with malignant bradycardia, pacemakers are prescribed.

Sinus bradycardia
Signs of pathological bradycardia:

Sinus tachycardia

The correct rhythm with a high heart rate (above 100 beats per minute) is called sinus tachycardia. Please note that normal heart rate varies with age, for example, in infants, the heart rate can reach 150 beats per minute, which is considered normal.
Advice! At home, with severe tachycardia, a strong cough or pressure on the eyeballs can help. These actions encourage nervus vagus which activates the parasympathetic nervous system causing the heart to beat more slowly.

Sinus tachycardia
Signs of pathological tachycardia:

Atrial fibrillation

Atrial fibrillation is an abnormal heart rhythm characterized by rapid and irregular atrial contraction. Most episodes are asymptomatic. Sometimes an attack is accompanied by the following symptoms: tachycardia, fainting, dizziness, shortness of breath, or chest pain. The disease is associated with an increased risk of heart failure, dementia, and stroke.

Atrial fibrillation
Signs of atrial fibrillation:

Important! Despite the above explanations with the interpretation of the data, the conclusion on the ECG should be made only by a qualified specialist - a cardiologist or a general practitioner. Interpretation of the electrocardiogram and differential diagnosis requires higher medical education.

How to "read" myocardial infarction on an ECG?

For students beginning the study of cardiology, the question often arises, how to learn how to read a cardiogram correctly and identify myocardial infarction (MI)? You can “read” a heart attack on a paper tape by several signs:

• elevation of the ST segment;
• peaked T wave;
• deep Q wave or its absence.

In the analysis of the results of electrocardiography, these indicators are first of all identified, and then dealt with others. Sometimes the earliest sign of an acute myocardial infarction is only a peaked T-wave. In practice, this is quite rare, because it appears only 3-28 minutes after the onset of a heart attack.
Peaked T-waves should be distinguished from peak T-waves associated with hyperkalemia. In the first few hours, the ST segments usually rise. Abnormal Q waves may appear within a few hours or after 24 hours.
Often there are long-term ECG changes, for example, constant Q-waves (in 93% of cases) and peaked T-waves. Stable ST segment elevation is rare, with the exception of ventricular aneurysms.
There are widely researched clinical solutions, such as the TIMI score, which help predict and diagnose myocardial infarction based on clinical data. For example, TIMI scores are often used to predict the condition of patients with symptoms of MI. Based on symptoms and electrocardiographic findings, practitioners can distinguish between unstable angina and MI in the emergency setting.

ECG for dummies: norms and interpretation

An electrocardiogram is an important tool for diagnosing the state of the cardiovascular system. One of the features of human health is that a person may not feel that something is wrong with him. He can afford big physical exercise while he is undergoing painful processes that can lead to rather unpleasant consequences.

Pain in the region of the heart is often just one of these hidden diseases. Of course, if a person is attentive to his health and turns to a qualified doctor for help at the first alarming signs, then he has a high chance of detecting the disease in time and taking necessary measures for his treatment.
But, do we always tend to act like this? Don't we usually prefer to endure mild pain without going to the doctor, especially since sometimes it goes away without consequences?
But not everything is always so simple and harmless. It is no secret that angina pectoris can cause pain that does not manifest itself in the region of the heart at all, but in other parts of the body. How to make the correct diagnosis?
There may also be another problem. For one reason or another, a person suffered a heart disease (sometimes, in rare cases, it is possible to endure a heart attack) and everything somehow survived, but the person does not know this. Well, something hurt, then it went away. How to diagnose what really happened to him?
This article will talk in more detail about what exactly this important diagnostic tool for the cardiovascular system is.
It should also be noted that an ordinary patient is poorly oriented in the indicators that are displayed here. If a person understands better how to read it correctly, he will be able to get important information about your health from the ECG.

What is an ECG, how is the procedure

The principle of obtaining an ECG is very simple. We are talking about the fact that sensors are attached to the skin of the patient, which record electrical impulses that accompany the beating of the heart. Recording is done on a piece of paper. A competent doctor can tell a lot about the patient's health from this diagram.
It depicts cyclical changes in the corresponding electrical impulses. It is important to note that this diagnostic method is not absolutely accurate and exhaustive. It can be considered, rather, as a basis for the main conclusions.
What exactly is shown in the ECG?

Suppose you need to take an electrocardiogram. How to do it right? Do I need to be a specialist in order to carry out this procedure, or if all the necessary rules are carefully followed, even a non-specialist can carry out the procedure? Let's try to answer these questions.
Interestingly, the electrocardiogram is used not only in the treatment of cardiac patients, but also in a number of other cases:

• This takes place not only during various medical examinations, but also for the diagnosis of those diseases that are not directly related to the heart, but can create complications in it.
• Also, when using those medicines that have a strong effect on the body, the health of the cardiovascular system is often checked in this way in order to prevent possible consequences taking such medications.
  In such cases, it is customary to check not only before, but also after the therapeutic course is completed.

The procedure itself is not very complicated. Its total duration does not exceed ten minutes. The room temperature must not be too low. At the same time, the room must be ventilated. Compliance with this and similar rules is very important for such a procedure. This is due to the fact that any change in the patient's physical condition will be reflected in the electrocardiogram.
We also invite you to learn more about cardiography of the heart.
Here are some other requirements:

Diagnostic technique including

It includes the attachment of four electrodes to the hands and ankles and the installation of six suction cups on the patient's chest.
Do it in the following order. Each electrode has a specific color. Put a damp cloth under them. This is done both to increase conductivity and to improve the adhesion of the electrode to the skin surface.
When installing suction cups on the chest, the skin is usually disinfected with an alcohol solution. The diagram will display several types of teeth that have a different shape.
To carry out diagnostics, it is enough to record data for no longer than four consecutive cycles.
There are several main options:

• This should be done if you clearly feel discomfort in the chest.
• With shortness of breath, although it may look familiar, it makes sense to see a doctor for an ECG.
• If you are overweight, then you are undoubtedly at risk for heart disease. It is recommended to do an electrocardiogram regularly.
• The presence of chronic and severe stress in your life is a danger not only to your heart, but also to other systems of the human body. An ECG in such a case is a matter of vital importance.
• There is such chronic illness like tachycardia. If you suffer from it, then the ECG should be done regularly.
• Hypertension is considered by many as a possible step towards a heart attack. If at this stage you regularly diagnose using an ECG, then your chances of recovering will increase dramatically.
• Before performing a surgical operation, it is important for the doctor to make sure. That your heart can handle it. An ECG may be done to check.

How often is it necessary to resort to such a procedure? This is usually determined by the attending physician. However, if you are over forty, then it makes sense to carry out this procedure annually. If you are much older, then you should do an ECG at least once a quarter.

What does the ECG show

Let's see what we can see on the electrocardiogram:

Principles for decoding indicators

A cardiogram is not one, but several different graphs. Since several electrodes are attached to the patient, electrical impulses can in principle be measured between each pair of them. In practice, the ECG contains twelve graphs. The doctor evaluates the shape and frequency of the teeth, and also considers the ratio of electrical signals on various graphs.
Each disease corresponds to specific signs on the ECG graphs. If they are determined, then this makes it possible to make the correct diagnosis to the patient. The norm and violations in the interpretation of the ECG are very important. Each indicator requires itself attentive attitude. A reliable result occurs when the analysis is carried out accurately and reliably.

reading teeth

There are five various kinds teeth on the cardiogram. They are designated in Latin letters: S, P, T, Q And R. Each of them characterizes the work of one of the departments of the heart. Different types of intervals and segments are also taken into account. They represent the distance between certain types of teeth and also have their own letter designations.
Also, the analysis considers the QRS complex (it is also called the QRS interval).
In more detail, the elements of the ECG are shown in the figure given here. This is a kind of ECG decoding table. First, the heart rate is assessed. As you know, it is usually 60-80 cuts per second.

How the doctor analyzes the results

The study of the electrocardiogram occurs in several successive stages:

Normal indicators for adults:

• P - normally should be positive, shows the presence of bioelectricity in the atria;
• The Q wave is normally negative, it refers to the interventricular septum;
• R - characterizes the electrical potential in the ventricular myocardium;
• The S wave - in a normal situation, it is negative, shows the final process of electricity in the ventricles, normally such a tooth will be lower than the R wave;
• T - must be positive, here we are talking about the recovery process of biopotential in the heart.
• The heart rate should be between 60 and 80 per minute. If it goes beyond these boundaries, then this indicates violations in the work of the heart.
• QT - the interval is normal for an adult is 390-450 milliseconds.
• The width of the QRS interval should be approximately 120 milliseconds.

Possible errors in the result

Despite its obvious advantages, this procedure also has certain disadvantages:

Pathologies in the interpretation of the ECG can be determined according to available descriptions various options cardiogram. There are detailed tables that will help determine the type of pathology detected. To increase the reliability of the result, the cardiogram should be combined with other diagnostic methods.

Cost of the procedure

If we talk about prices in Moscow, then they are approximately in the range from 650 to 2300 rubles. Let's not forget that, when receiving a cardiogram, its analysis by a qualified doctor and the quality of the medical equipment itself are of great importance.
In St. Petersburg, the average price is about the same as in Moscow. ECG price with decoding is approximately 1500 rubles for this procedure.
There is also a service to call such a specialist at home. In Moscow, this service can be provided for 1500 rubles, in Khabarovsk - for 900 rubles, and in Saratov it can be done for 750 rubles.

Conclusion

An ECG is an important means of diagnosing your cardiovascular system. She has a lot to say about her. It makes sense to regularly, at least once every two years, seek an ECG from a doctor.

ECG interpretation of an electrocardiogram is considered a complex process that only a diagnostician or cardiologist can do. They carry out decoding, revealing various defects and disorders of the human heart muscle. Such diagnostic method widely used today in all medical institutions. The procedure can be done both in the clinic and in the ambulance.

Electrocardiography is a science in which the rules of the procedure are studied, how to decipher the results obtained and explains the unclear points and situations. With the development of the Internet, ECG decoding can even be done independently, using special knowledge.

The electrocardiogram is deciphered by a special diagnostician who uses the established procedure that determines normal indicators and their deviations.

Heart rate and heart rate are assessed. In the normal state, the rhythm should be sinus, and the frequency should be from 60 to 80 beats per minute.

Intervals are calculated that characterize the duration of the moment of contraction. This is where special formulas come into play.

The normal interval (QT) is 390 - 450 ms. If the interval is violated, if it lengthens, the diagnostician may suspect that the patient has atherosclerosis, rheumatism or myocarditis, as well as coronary artery disease. Also, the interval may be reduced, and this indicates the presence of hypercalcemia disease. These parameters are calculated by a specialized automatic program that provides a reliable result.

The location of the EOS is calculated from the isoline along the height of the teeth. If the indicators are significantly higher than each other, a deviation of the axis is noticed, defects in the vital activity of the right or left ventricle are suspected.

An indicator showing the activity of the ventricles, the QRS complex, is formed during the passage of electrical impulses to the heart. It is considered normal when there is no defective Q wave and the distance does not exceed 120 ms. When the specified interval is shifted, it is customary to speak of a conduction defect, or it is also called the blockade of the legs of the His bundle. With incomplete blockade, RV or LV hypertrophy can be suspected, depending on the location of the line on the ECG. The interpretation describes ST particles, which are reflectors of the recovery time of the initial position of the muscle relative to its complete depolarization. Under normal conditions, the segments should fall on the isoline, and the T wave, which characterizes the work of both ventricles, should be asymmetric and directed upwards. It must be longer than the QRS complex.

Correctly deciphering ECG indicators can only be done by doctors who are specially involved in this, but often an ambulance paramedic with extensive experience can easily recognize common heart defects. And this is extremely important in emergency situations.

When describing and decoding the diagnostic procedure, various characteristics of the work of the heart muscle are described, which are indicated by numbers and Latin letters:

• PQ is an indicator of atrioventricular conduction time. In a healthy person it is 0.12 - 0.2 s.
• R - description of the work of the atria. It may well tell about atrial hypertrophy. In a healthy person, the norm is 0.1 s.
• QRS - ventricular complex. In the normal state, the indicators are 0.06 - 0.1 s.
• QT is an indicator that can indicate cardiac ischemia, oxygen starvation, heart attack, and rhythm disorders. The normal indicator should be no more than 0.45 s.
• RR is the gap between the upper points of the ventricles. Shows the constancy of heart contractions and allows you to count their frequency.

Cardiogram of the heart: decoding and main diagnosed diseases

Deciphering a cardiogram is a long process that depends on many indicators. Before deciphering the cardiogram, it is necessary to understand all the deviations of the work of the heart muscle.

Atrial fibrillation is characterized by irregular contractions of the muscle, which can be quite different. This violation is dictated by the fact that the beat is set not by the sinus node, as it should happen in a healthy person, but by other cells. The heart rate in this case ranges from 350 to 700. In this condition, the ventricles do not fully fill with incoming blood, which causes oxygen starvation, from which all organs in the human body suffer.

An analogue of this condition is atrial fibrillation. The pulse in this state will be either below normal (less than 60 beats per minute), or close to normal (from 60 to 90 beats per minute), or above the specified norm.

On the electrocardiogram, you can see frequent and constant contractions of the atria and less often of the ventricles (usually 200 per minute). This is atrial flutter, which often occurs already in the exacerbation phase. But at the same time, it is easier for the patient to tolerate than flicker. Circulatory defects in this case are less pronounced. Trembling can develop as a result of surgical interventions, with various diseases such as heart failure or cardiomyopathy. At the time of examination of a person, flutter can be detected due to rapid rhythmic heartbeats and pulse, swollen veins in the neck, increased sweating, general impotence and shortness of breath.

Conduction disorder - this type of heart disorder is called blockade. The occurrence is often associated with functional disorders, but there are also the result of intoxications of a different nature (against the background of alcohol or taking medicines), as well as various diseases.

There are several types of disorders that the cardiogram of the heart shows. Deciphering these violations is possible according to the results of the procedure.

Sinoatrial - with this type of blockade, there is difficulty in the exit of the impulse from the sinus node. As a result, there is a syndrome of weakness of the sinus node, a decrease in the number of contractions, defects in the circulatory system, and as a result, shortness of breath, general weakness of the body.

Atrioventricular (AV blockade) - characterized by a delay in excitation in the atrioventricular node longer than the set time (0.09 seconds). There are several degrees of this type of blocking.

The number of contractions depends on the magnitude of the degree, which means that the defect in the blood flow is more difficult:

• I degree - any compression of the atria is accompanied by an adequate amount of compression of the ventricles;
• II degree - a certain amount of atrial compression remains without ventricular compression;
• III degree (absolute transverse blockade) - the atria and ventricles are compressed independently of each other, which is well shown by the decoding of the cardiogram.

Conduction defect through the ventricles. An electromagnetic impulse from the ventricles to the muscles of the heart propagates through the trunks of the bundle of His, its legs and branches of the legs. Blocking can occur at every level, and this will immediately affect the electrocardiogram of the heart. In this situation, it is observed that the excitation of one of the ventricles is delayed, because the electrical impulse goes around the blockage. Doctors divide the blockage into complete and incomplete, as well as permanent or non-permanent blockade.

Myocardial hypertrophy is well shown by the cardiogram of the heart. Decoding on an electrocardiogram - this condition shows a thickening of individual sections of the heart muscle and stretching of the chambers of the heart. This happens with regular chronic overload of the body.

• Syndrome of early repolarization of the ventricles. Often, it is the norm for professional athletes and people with congenital large body weight. clinical picture does not give and often passes without any changes, so the interpretation of the ECG becomes more complicated.
• Various diffuse disorders in the myocardium. They indicate a myocardial malnutrition, as a result of dystrophy, inflammation or cardiosclerosis. Disorders are quite susceptible to treatment, often associated with a disorder of the body's water and electrolyte balance, taking medications, and heavy physical activity.
• Non-individual ST changes. A clear symptom of myocardial supply disorder, without bright oxygen starvation. Occurs during hormonal imbalances and electrolyte imbalances.
• T wave distortion, ST depression, low T. Cat's back on the ECG shows the state of ischemia (oxygen starvation of the myocardium).

In addition to the disorder itself, they also describe their position in the heart muscle. The main feature of such disorders is their reversibility. The indicators, as a rule, are given for comparison with old studies in order to understand the patient's condition, since it is almost impossible to read the ECG on your own in this case. If a heart attack is suspected, additional studies are carried out.

There are three criteria by which a heart attack is characterized:

• Stage: acute, acute, subacute and cicatricial. Duration from 3 days to a life-long condition.
• Volume: large-focal and small-focal.
• Location.

Whatever the heart attack, it is always a reason to place a person under strict medical supervision, without any delay.

ECG results and options for describing the heart rhythm

The results of the ECG provide an opportunity to look at the state of the work of the human heart. There are different ways to decipher the rhythm.

sinus is the most common signature on an electrocardiogram. If, apart from heart rate, no other indicators are indicated, this is the most successful forecast, which means that the heart is working well. This type of rhythm suggests a healthy state of the sinus node, as well as the conduction system. The presence of other records proves the existing defects and deviations from the norm. There is also atrial, ventricular or atrioventricular rhythm, which indicate which cells in specific parts of the heart set the rhythm.

sinus arrhythmia is often normal in young adults and children. This rhythm is characterized by the exit from the sinus node. However, the intervals between contractions of the heart are different. This is often associated with physiological disorders. Sinus arrhythmia should be carefully monitored by a cardiologist to avoid the development of serious diseases. This is especially true for people with a predisposition to heart disease, as well as if the arrhythmia is caused by infectious diseases and heart defects.

Sinus bradycardia- characterized by rhythmic contraction of the heart muscle with a frequency of about 50 beats. In a healthy person, this condition can often be observed in a state of sleep. Such a rhythm can manifest itself in people professionally involved in sports. They have ECG teeth that are different from the teeth of an ordinary person.

Constant bradycardia may characterize the weakness of the sinus node, manifested in such cases by more rare contractions at any time of the day and in any condition. If a person has pauses during contractions, then a surgical intervention is prescribed to install a stimulator.

Extrasystole. This is a rhythm defect that is characterized by extraordinary contractions outside the sinus node, followed by ECG results showing an extended pause, called a compensatory one. The patient feels the heartbeat as uneven, chaotic, too fast or too slow. Sometimes patients are disturbed by pauses in the heart rhythm. Often there is a feeling of tingling or unpleasant jolts behind the sternum, as well as a feeling of fear and emptiness in the stomach. Often such conditions do not lead to complications and do not pose a threat to a person.

Sinus tachycardia- with this disorder, the frequency exceeds the normal 90 beats. There is a division into physiological and pathological. Under the physiological understand the onset of such a state in a healthy person under certain physical or emotional stress.

It can be observed after taking alcoholic beverages, coffee, energy drinks. In this case, the condition is temporary and passes quite quickly. The pathological type of this condition is characterized by periodic heartbeats that disturb a person at rest.

The causes of the pathological appearance can be elevated body temperature, various infectious diseases, blood loss, long periods without water, anemia, etc. Doctors are treating the underlying disease, and tachycardia is stopped only in case of a heart attack in a patient or an acute coronary syndrome.

Paroxysmal tachycardia- in this condition, a person has a rapid heartbeat, expressed in an attack lasting from several minutes to several days. The pulse may increase to 250 beats per minute. There are ventricular and supraventricular forms of such tachycardia. The main reason for this state is the defect in the passage of the electric pulse in the conducting system. This pathology is quite susceptible to treatment.

You can stop the attack at home with the help of:

• Holding the breath.
• Forced cough.
• Dive into cold water faces.

WPW syndrome It is a subspecies of supraventricular tachycardia. The main provocateur of an attack is an additional nerve bundle, which is located between the atria and ventricles. To eliminate this defect, surgical intervention or medication is required.

CLC- very similar to the previous type of pathology. The presence of an additional nerve bundle here contributes to the early excitation of the ventricles. The syndrome, as a rule, is congenital and manifests itself in a person with attacks of a rapid rhythm, which is very well shown by ECG teeth.

Atrial fibrillation May be episodic or permanent. A person feels pronounced atrial flutter.

ECG of a healthy person and signs of changes

The ECG of a healthy person includes many indicators by which a person's health is judged. The ECG of the heart plays a very important role in the process of detecting abnormalities in the work of the heart, the most terrible of which is myocardial infarction. Exclusively with the help of electrocardiogram data, it is possible to diagnose necrotic infarct zones. Electrocardiography also determines the depth of damage to the heart muscle.

ECG norms of a healthy person: men and women

ECG norms for children

The ECG of the heart is of great importance in the diagnosis of pathologies. The most dangerous heart disease is myocardial infarction. Only an electrocardiogram will be able to recognize necrotic infarction zones.

ECG signs of myocardial infarction include:

• the area of ​​necrosis is accompanied by changes complex Q-R-S, resulting in a deep Q wave;
• the damage zone is characterized by displacement (elevation) segment S-T, smoothing the R wave;
• the ischemic zone changes the amplitude and makes the T wave negative.

Electrocardiography also determines the depth of damage to the heart muscle.

How to decipher the cardiogram of the heart yourself

Not everyone knows how to decipher the cardiogram of the heart. However, having a good understanding of the indicators, you can independently decipher the ECG and detect changes in the normal functioning of the heart.

First of all, it is worth determining the indicators of the heart rate. Normally, the heart rhythm should be sinus, the rest indicate the possible development of arrhythmia. Changes in sinus rhythm, or heart rate, suggest the development of tachycardia (speeding up) or bradycardia (slowing down).

Abnormal data of teeth and intervals are also important, since you can read the cardiogram of the heart yourself by their indicators:

1. Prolongation of the QT interval indicates the development of coronary heart disease, rheumatic disease, sclerotic disorders. Shortening of the interval indicates hypercalcemia.
2. An altered Q wave is a signal of myocardial dysfunction.
3. The sharpening and increased height of the R wave indicates hypertrophy of the right ventricle.
4. A split and dilated P wave indicates left atrial hypertrophy.
5. An increase in the PQ interval and a violation of the conduction of impulses occurs with atrioventricular blockade.
6. The degree of deviation from the isoline in the R-ST segment diagnoses myocardial ischemia.
7. Elevation of the ST segment above the isoline is a threat of acute infarction; a decrease in the segment registers ischemia.

The cardio line consists of divisions (scales) that determine:

• heart rate (HR);
• QT interval;
• millivolts;
• isoelectric lines;
• duration of intervals and segments.

This simple and easy-to-use device is useful for everyone to independently decipher the ECG.

The heart rate may be regular or irregular.

Irregular rhythms can be:

• Regularly irregular (i.e., the pattern of irregularity is repeated).
• Irregularly irregular (the rhythm is completely disorganized).

You can distinguish a regular rhythm from an irregular one as follows: Several consecutive R-R intervals are marked on a sheet of paper. Rhythm bars are then moved along them to check if the next intervals match.

The nuance of ECG decoding: If there is a suspicion that there is some kind of atrioventricular blockade, you need to specify separately the rate of contractions of the atria and ventricles (i.e., P-waves and R-waves are noted separately. When there is movement along the rhythm strip, then you can see whether the PR interval changes.

A similar change can be observed in the absence of QRS complexes or complete dissociation between them. If we additionally measure R-R intervals, then it will be possible to find out whether the rhythm is regular or irregular.

cardiac axis

The cardiac axis represents the general direction of the electrical location of the heart.

In a healthy person, the axis should be directed from 11 o'clock to 5 o'clock (if measured by the dial).

To determine the cardiac axis, look at the standard leads I, II, and III.

With a normal cardiac axis:

• Lead II has the most positive deviation compared to leading leads I and III

When tilted to the right:

• Lead III has the most positive deflection, and lead I should be negative.

A similar change is usually observed in individuals with right ventricular hypertrophy.

When the axis is tilted to the left:

• Lead I has the largest positive deviation.
• Leads II and III are negative.

Axis deviation to the left is observed in individuals with impaired cardiac conduction.

Video: Norma ECG (Russian voiceover)

Main characteristics and changes of the ECG

P wave

The following questions are often associated with P-wave analysis:

• Are there P-waves?
• If so, is every P wave accompanied by a QRS complex?
• P-waves look normal? (test duration, direction and form)
• If not, is there any atrial activity, eg sawtooth baseline → flutter waves / chaotic baseline → fibrillating waves / flat line → no atrial activity at all?

Nuance of deciphering the ECG: If there are no P-waves and there is an irregular rhythm, this can provoke atrial fibrillation.

P-R interval

The P-R interval should be between 120 and 200ms (3-5 small squares)

Long PR interval is more than 0.2 seconds. Its presence may be associated with atrioventricular delay (AV block).

First degree heart block

First degree heart block includes a fixed long PR interval (greater than 200 ms).

Second degree heart block (Mobitz type 1)

If the PR interval slowly increases, then a shedding QRS complex occurs, which corresponds to Mobitz type 1 AV block.

Second degree heart block (Mobitz type 2)

If the PR interval is fixed, but there is a decrease in the isoline, then they speak of AV blockade type Mobitz 2, and the frequency of the falling beats must be specified, for example, 2:1, 3:1, 4:1.

Third degree heart block ( complete blockade hearts)

If the P waves and QRS complexes are completely unrelated, this is third-degree AV block.

Tips for remembering types of heart block

1. To remember the presented degrees of AV blockade, it is useful to visually perceive the anatomical location of the blockade in the conduction system of the heart:
1.1 First-degree AV block occurs between the sinoatrial node (SA node) and the AV node (that is, inside the atrium).
1.2 Second-degree AV block (Mobitz I) is defined at the level of the AV node. This is the only segment of the conduction system of the heart that has the ability to translate incoming impulses from a higher speed to a lower one. Mobitz II - occurs after the AV node in the bundle of His or Purkinje fibers.
1.3 The third level of AV block occurs below the AV node, resulting in complete blocking of impulse conduction.

Shortened PR interval

If the PR interval is short, it means one of two things:

1. The P wave originates from closer to the AV node, so conduction takes less time (the SA node is not in a fixed location, and some atria are smaller than others!).
2. The atrial impulse reaches the ventricle faster instead of slowly passing through the atrial wall. This may be an auxiliary path associated with the delta wave. A similar ECG is often observed in patients with Wolff-Parkinson-White syndrome.

QRS complex

There are several characteristics of the QRS complex that need to be assessed:

• Width.
• Height.
• Morphology.

Width of the QRS complex

The width can be described as narrow (NARROW, less than 0.12 seconds) or wide (BROAD, more than 0.12 seconds).

A narrow QRS complex occurs when an impulse is conducted along the bundle of His and Purkinje fibers into the ventricles. This results in a well orchestrated synchronous depolarization of the ventricles.

A wide QRS complex occurs if there is an abnormal depolarization sequence - for example, ventricular ectopia, when an impulse slowly spreads through the myocardium from a focus in the ventricle. With atrial ectopia, a narrow QRS complex is most often determined, because the impulse travels along the normal cardiac conduction system. Similarly, branch block results in a wide QRS because the impulse travels quickly into one ventricle through the internal conduction system and then slowly travels through the myocardium into the other ventricle.

Height of the QRS complex

Described as small (SMALL) and tall (TALL).

Small ventricular complexes are defined at a height below 5 mm in the main leads or less than 10 mm in the chest leads.

High QRS complexes most often indicate ventricular hypertrophy (although the changes may be related to the person's constitution, such as pain and growth). There are many algorithms for measuring ventricular hypertrophy, mainly the left one, among which the Sokolov-Lyon index or the Cornell index are most often used.

Morphology of the QRS complex

During the decoding of the ECG, individual elements of the QRS complex are evaluated.

• delta wave

The appearance of a delta wave is a sign that the ventricles are firing earlier than usual. Early activation followed by slow propagation of the impulse through the myocardium causes an indistinct burst of the QRS complex. At the same time, the presence of a delta wave does not allow us to speak unambiguously about the Wolff-Parkinson-White syndrome. In such cases, tachyarrhythmias in combination with delta waves should be determined for confirmation.

• Q-wave

Isolated Q waves can be detected in the normal state. The pathological Q wave is more than 25% of the size of the R wave that follows it, or more than 2 mm in height and more than 40 ms in width. Sometimes it is enough to see Q waves on various ECG leads to obtain evidence of a previous myocardial infarction.

Q waves (V2-V4), with T wave inversion, may indicate a previous anterior myocardial infarction.

• R- and S-waves

The R-wave is characterized by a progression in the chest leads (starting small in V1 and ending with a large one in V6). The transition from the S>R wave to R> S should occur in leads V3 or V4. Poor progression (i.e., S > R to leading V5 and V6) may be a sign of previous MI. It is also sometimes determined in people of very large stature due to the location.

• J dot segment

The J-point is when the S-wave connects the ST segment. This point can be raised, causing the ST segment that follows it to also rise and then speak of a “high takeoff”.

High take-off (or benign early repolarization) is a normal ECG variant that causes many different negative interpretations, since they mainly look at the height of the ST segment.

Important features:

• Benign early repolarization occurs mainly before the age of 50 years (in people over 50 years of age, ischemia is more common, which should be suspected in the first place).
• Typically, the J-point is associated with ST elevation in many leads, making ischemia less likely.
• T waves also rise (unlike STEMI, that is, myocardial infarction, when the T wave remains unchanged and the ST segment rises).
• The changes associated with benign repolarization do not change much over time, unlike myocardial infarction, because during STEMI changes will be observed after a week or two or more.

ST segment

The ST segment is the part of the ECG between the end of the S wave and the beginning of the T wave. In a healthy person, this segment is comparable to the isoelectric line, which is neither increased nor decreased. ST segment anomalies are examined to rule out pathology.

ST segment elevation

ST elevation is considered significant when it is greater than 1 mm (1 small square) in two or more adjacent standard leads or greater than 2 mm in two or more chest leads. This is most often associated with acute macrofocal myocardial infarction.

ST segment depression

ST-segment depression is said to be in the case when its decrease relative to the isoline by more than 0.5 mm in two or more adjacent leads is observed, which indicates myocardial ischemia.

T wave

T wave formation is associated with ventricular repolarization.

Tall T waves

T waves are considered high if they:

• More than 5 mm in standard leads.
• More than 10 mm in the chest leads (same criteria as for “small” QRS complexes).

Tall T waves may be associated with:

• Hyperkalemia.
• Acute myocardial infarction.

Inverted T waves

T waves are usually inverted in V1, i.e. in the first chest lead, and inversion in the standard lead III is also a normal variant.

Inverted T waves in other leads are nonspecific signs of a wide range of disorders:

• ischemia.
• Blockade of Purkinje fibers.
• Pulmonary embolism.
• Hypertrophy of the left ventricle (in lateral leads).
• Hypertrophic cardiomyopathy (widespread).
• Generalized pathological process.

When transcribing the ECG, commentary may be added regarding the distribution of T-wave inversion, for example. front / side / rear.

Biphasic T waves

Biphasic T waves have two peaks and may indicate ischemia and hypokalemia.

Flat T-waves

Another non-specific sign that may indicate ischemia or electrolyte imbalance.

U wave

U-waves are more than 0.5 mm off-center after T-waves are best defined in precordial leads V2 or V3.

The teeth become larger when the rhythm slows down (bradycardia). Classically, U-waves are detected with various electrolyte imbalances, hypothermia, or antiarrhythmic therapy with drugs such as digoxin, procainamide, or amiodarone.

Key points

• The heart can have a different position in the chest, which depends a lot on the physique of the person, the state of the heart cavities (their dilatation or hypertrophy), the presence of concomitant pathologies from the pulmonary system, etc.
• V1-V3 can become "right ventricular" if the right ventricle is enlarged, causing the heart to rotate and the right ventricle to come forward.
• Pronounced dilatation of the left ventricle may otherwise be deciphered on the ECG, for example, V5-V6 will show the apex of the heart.
• When deciphering the ECG in different medical institutions chest leads may vary slightly as nurses often place electrodes differently.

Video: ECG norm. All intervals and waves: p, QRS, T, PR, ST