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Deviations in the ECG of the heart. What does an ECG show in adults?

ECG interpretation is performed by a qualified specialist. This functional diagnostic method checks:

Heart rhythm: what is the state of the electrical impulse generators and the cardiac systems that conduct these impulses.
Heart muscle: its condition and performance, damage, inflammation and other pathological processes that could affect the condition of the heart.

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Heart rate

Patients receive an electrocardiogram along with its results. It is impossible to decipher it yourself. To read the diagram, you will need special medical education. There is no need to be nervous before meeting with a functional diagnostician. At the appointment, he will explain all the risks of the diagnosis and prescribe effective treatment. But if the patient is diagnosed with a serious illness, then a consultation with a cardiologist will be required.

When the ECG interpretation does not give clear results, the doctor may prescribe additional studies:

ECG control;
Holter (monitoring of heart function throughout the day);
Ultrasound of the heart muscle;
Treadmill (test for heart performance during exercise).

The results of measurements using these studies are an accurate indicator of heart function. If there are no malfunctions in the myocardium, the tests will have good results.

On the ECG of a healthy person, the inscription “Sinus rhythm” is found. If a frequency of beats per minute up to 90 is added to this inscription, the results are good, the heart works without interruption. Sinus rhythm is an indicator of the rhythm of the sinus node, which is the main rhythm producer for regulating and generating electrical impulses with the help of which the heart muscle contracts. An electrocardiogram description that includes sinus rhythm is the norm, indicating the health of the sinus node and the heart muscle itself.

If the heart cardiogram does not have any other marks in its description, it indicates complete heart health. Sinus rhythm can be replaced by atrial, atrioventricular or ventricular. These types of rhythms indicate that contractions are carried out precisely by these parts of the heart, which is considered a pathology.

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What is sinus arrhythmia?

Sinus arrhythmia is a common diagnosis in childhood and adolescence. It is characterized by different time intervals between sinus contractions of the heart muscle. Experts say that this pathology can be caused by changes at the physiological level. Up to 40% of sinus arrhythmias should be controlled by a cardiologist. Patients should be examined and re-tested every 3-4 months. Such precautions will protect you as much as possible from the development of more serious heart diseases.

Sinus bradycardia is a rhythm of heart contractions up to 50 times per minute. This phenomenon is also possible in healthy people during sleep or in professional athletes. Bradycardia of a pathological nature may be a sign of sick sinus syndrome. This case implies severe bradycardia, reaching up to 35 heartbeats per minute. This pathology can be observed all the time, and not just at night.

If bradycardia consists of pauses between contractions of up to 3 seconds during the day and up to 5 seconds at night, there may be a disruption in the supply of oxygen to the tissues, which usually leads to fainting. Only an electrical pacemaker, which is placed directly on the heart during surgery, will help get rid of this problem. The installation takes place at the site of the sinus node, which subsequently allows the heart to work without failures.

The causes of a poor cardiogram may be associated with sinus tachycardia, which is a contraction of the heart rate more than 90 times per minute. It is divided into tachycardia of a physiological and pathological nature. Healthy people can experience sinus tachycardia during physical and emotional stress, drinking coffee or strong tea, alcoholic drinks and energy drinks. Sinus tachycardia after active pastime is a brief manifestation. After the manifestation of an increased number of beats, the rhythm returns to its normal state in a fairly short time after reducing the intensity of physical activity.

With tachycardia of a pathological nature, a rapid heartbeat bothers the patient all the time. The cause of increased heart rate can be: increased body temperature, infection, blood loss, dehydration, anemia and more. The root cause causing tachycardia needs to be treated. Relief of sinus tachycardia occurs only in the case of myocardial infarction or acute coronary syndrome.

How does extrasystole manifest?

A specialist can identify this pathology immediately, since this is a change in rhythm, the nature of which is foci behind the sinus rhythm. They give extra contractions of the heart muscle. After this process, a pause doubled in time appears, the name of which is compensatory. Patients believe that such a change in heartbeat occurs due to nervous stress. Rhythm can be either rapid or slow, sometimes chaotic. The patient himself can notice the dips that occur in the rhythm of the heartbeat.

An example of deciphering an ECG with extrasystole is an example of pathology that is visible even to non-specialists. Some patients complain not only of changes in rhythm, but also of unpleasant and painful sensations in the chest area. They experience tremors, tingling, and a sinking feeling of fear rising in their stomach.

Such manifestations are not always pathological and life-threatening.

Many types of extrasystoles do not inhibit blood circulation and do not reduce the performance of the heart.

Extrasystoles are divided into 2 types:

functional (manifest against a background of panic and nerves);
organic (if a person has heart defects, myocarditis and congenital problems with the cardiovascular system).

In 20% of cases, the cause of the disease is intoxication or heart surgery. A single manifestation of extrasystole occurs rarely (up to 5 times in 1 hour). Such gaps are functional in nature and are not an obstacle to normal blood supply. There are moments when paired extrasystoles occur. They appear after a series of normal contractions. It is this rhythm that is an obstacle to the normal functioning of the heart muscle. For an accurate diagnosis of this manifestation, an additional ECG and Holter analysis is prescribed for a day.

Main classes of pathology

Extrasystoles also have the form of allorhythmia. When an extrasystole appears on every second contraction, experts diagnose bigeminy, on every third - trigeminy, on every fourth - quadrigeminy. According to Laum’s classification, extrasystoles of ventricular nature are divided into 5 classes depending on the daily examination indicators:

1. Single cases of disease manifestations up to 60 times every hour, united by one focus (monotopic).
2. Constant monotopic changes, occurring more than 5-6 times every minute.
3. Constant polymorphic (have different shapes) and polytopic (have different centers of occurrence) changes.
4. Paired or group, accompanied by episodic attacks of paroxysmal tachycardia.
5. Early manifestation of extrasystoles.

No medications are prescribed for treatment. When the disease manifests itself less than 200 times a day (Holter monitoring will help establish the exact number), extrasystoles are considered safe, so there is no need to worry about their manifestations. Regular examinations by a cardiologist are required every 3 months.

If the patient’s electrocardiogram reveals pathological contractions more than 200 times every day, then additional examinations are prescribed. Specialists prescribe ultrasound of the heart and magnetic resonance imaging (MRI) of the heart muscle. Treatment of manifestations is specific and requires a special approach, since it is not the extrasystoles that are treated, but the root causes of their occurrence.

Paroxysmal tachycardia

Paroxysm is a manifestation of an attack. This process of increased heart rate can last for several hours or several days. The electrocardiogram displays equal intervals between muscle contractions. But the rhythm changes and can reach more than 100 beats in 1 minute (average figures - 120-250 times).

Doctors distinguish supraventricular and ventricular types of tachycardia. The basis of this pathology is the abnormal circulation of electrical impulses in the cardiovascular system. You can get rid of this manifestation at home, but for a while: you need to hold your breath, start coughing hysterically, or dip your face in cold water. But such methods are ineffective. Therefore, there is a medical method for the treatment of paroxysmal tachycardia.

One of the types of supraventricular tachycardia is Wolff-Parkinson-White syndrome. The title includes the names of all the doctors who described it. The reason for this type of tachycardia is the appearance of an extra bundle of nerves between the atria and ventricles, which conducts the rhythm faster than the main driver. As a result, the heart contracts one extra time. This pathology can be treated conservatively or surgically. The operation is prescribed only in case of low effectiveness or the patient is allergic to the active components of treatment, in case of atrial fibrillation or heart defects of various types.

Clerk-Levy-Christesco syndrome is a manifestation similar to the previous pathology, but it is characterized by earlier than normal stimulation of the ventricles with the help of an additional bundle through which the nerve impulse passes. The syndrome is a congenital pathology. If you decipher the cardiogram of the heart, its manifestation can be seen immediately by attacks of rapid heartbeat.

Atrial fibrillation

During fibrillation, irregular contractions of the heart muscle are observed with intervals between contractions of varying lengths. This is explained by the fact that the rhythm is set not by the sinus node, but by other cells of the atria. The frequency of contractions can reach even 700 beats in 1 minute. Full contraction of the atria is simply absent; it occurs due to muscle fibers, which do not allow the ventricles to be completely filled with blood. The consequence of this process is a deterioration in the heart’s output of blood, which leads to oxygen starvation of organs and tissues of all body systems.

Atrial fibrillation also has another name: atrial fibrillation. In fact, not all atrial contractions travel directly to the ventricles. This results in a decrease in the normal heart rate (bradysystole, which has a beat rate of less than 60 times per minute). But the heart contraction can be normal (normosystole, 60-90 times per minute) or increased (tachysystole, more than 90 times per minute).

Determining atrial fibrillation on an electrocardiogram is easy, since attacks are difficult to miss. The onset of an attack in 90% of cases is a strong shock to the heart muscle. Next, a series of arrhythmic oscillations of the heart develops with an increased or normal frequency. The patient's condition also worsens: he becomes weak, sweaty, and dizzy. The patient awakens to a pronounced fear of death. Shortness of breath and an agitated state may occur. Sometimes loss of consciousness occurs. Reading a cardiogram at the final stage of an attack is also easy: the rhythm returns to normal. But the patient feels a strong desire to urinate, during which a fairly large amount of fluid comes out.

The disease is relieved using reflex methods, drugs in the form of tablets or injections. Less commonly, specialists perform cardioversion - stimulation of the heart muscle using an electric defibrillator. If attacks of ventricular fibrillation are not eliminated within 2 days, complications may occur. Pulmonary embolism and stroke may occur.

A constant form of flicker, in which neither medications nor electrical stimulation of the heart helps, becomes commonplace in the patient’s life and is felt only during tachysystole (increased heart rate). If the electrocardiogram reveals tachysystole and atrial fibrillation, then it is necessary to reduce the number of heart contractions to normal without trying to make them rhythmic. Atrial fibrillation can appear against the background of coronary heart disease, thyrotoxicosis, heart defects of various types, diabetes mellitus, sick sinus syndrome, intoxication after alcohol poisoning.

Atrial flutter

Atrial flutter is constant and frequent contractions of the atria (more than 200 times per minute) and ventricles (less than 200 times). Flutter in 90% of cases has an acute form, but is tolerated much better and easier than fibrillation, since changes in blood circulation are less pronounced. The development of flutter is possible against the background of heart disease (cardiomyopathy, heart failure), after surgery on the heart muscle. With obstructive pulmonary disease, it practically does not manifest itself. It is easy to read an ECG for this disease, as it is manifested by frequent rhythmic heartbeat, swollen veins in the neck, shortness of breath, increased sweating and weakness.

In the normal state, electrical excitation is generated in the sinus node, which passes through the conduction system. It experiences a physiological delay of literally a split second in the area of the atrioventricular node. The atria and ventricles, whose function is to pump blood, are stimulated by this impulse. When an impulse is delayed in some part of the system, it reaches other areas of the heart later, which leads to disruptions in the normal operation of the pumping system. Changes in conductivity are called blockade.

The occurrence of blockades is a functional disorder. But the reason for their occurrence in 75% of cases is alcohol or drug intoxication and organic diseases of the heart muscle. There are several types of blockades:

1. Sinoatrial block: the passage of an impulse directly from the sinus node is difficult. Then this blockade develops into sick sinus syndrome, leading to a decrease in the number of contractions until a new blockade occurs, impaired blood supply to the peripheral section, shortness of breath, weakness, dizziness and loss of consciousness.
2. Samoilov-Wenckebach block - the second degree of sinoatrial block.
3. Atrioventricular block is a delayed excitation of the atrioventricular node for more than 0.09 seconds. There are 3 degrees of blockade of this type. With the highest degree of disease, the ventricles contract more often. Therefore, at the highest stages, blood circulation disorders become more severe.

Conduction disturbances in the ventricles

The electrical signal travels inside the ventricles to special cells made of muscle tissue. The propagation of this signal is carried out through systems such as the bundle of His, its legs and their branches. The cause of a bad cardiogram is the occurrence of disturbances in the conductivity of the electrical signal. Specialists can easily diagnose this deviation from the norm on an ECG. At the same time, the diagram clearly shows that one of the ventricles is stimulated later than the second, because the signaling is produced with a delay, passing along bypass paths due to the blockade of the desired area.

The blockade is classified not only by place of origin, but also by type. There are complete and incomplete blockades, permanent and non-permanent. The root causes of blockades inside the ventricles are the same as in other diseases with poor conduction: ischemic disease, cardiomyopathy, defects of various types, fibrosis, cancer of the heart. The consumption of antiarrhythmic drugs, increased potassium levels in the blood, oxygen starvation, and more can affect the occurrence of the disease.

The most common blockage of the superior branch is on the left bundle branch. The second place is taken by the blockade of the entire area of the right leg. It does not occur due to other heart diseases. Left leg block occurs when the myocardium is damaged by a number of diseases. The lower branch of the left leg suffers from pathological changes in the structure of the human chest. It can also occur when the right ventricle is overloaded.

ECG is considered one of the most common and informative diagnostic techniques. With its help, a variety of cardiac pathologies are identified, and the effectiveness of treatment is also monitored. But what does an ECG of the heart show and how often can it be done? We will talk about its features below.

What is ECG

Electrocardiography is a method of examining the electrophysiological functioning of the heart muscle. When diagnosing, a special device is used that records the slightest changes in its activity, and then displays them in a graphical image. Conduction, contraction frequency, hypertrophic changes, scarring and other changes in myocardial function can all be detected using an ECG.

During the diagnostic process, special electrodes record the contraction of the heart, namely the bioelectric potentials that arise. Electrical excitation covers different parts of the heart muscle at different times, so a potential difference is recorded between the unexcited and excited parts. It is this data that is captured by electrodes placed on the body.

The video below will tell you about the indicators and features of the ECG in a simple and accessible form:

Who is it prescribed to?

ECG is used to diagnose a number of cardiac abnormalities. So, the indications for prescribing the procedure are:

Scheduled examination. Necessary for different categories of people, including adolescents, pregnant women, athletes, before surgical interventions or in the presence of any diseases (lung and gastrointestinal diseases, thyroid gland, diabetes).
For the diagnosis of secondary or primary diseases as a preventive measure or to identify possible complications.
Carrying out monitoring during the treatment period or after its completion if any diseases are detected.

An electrocardiogram is performed if there are indications for using this diagnostic method. It is also required when undergoing a medical examination of drivers, the draft board, or when being sent for treatment to a sanatorium. For pregnant women, the test is done at least 2 times: at the time of registration and before giving birth.

Why do it?

Diagnostics helps to determine the early stages of cardiac dysfunction, as well as the prerequisites for the development of serious pathologies. An electrocardiogram is able to detect the slightest changes occurring in the heart: thickening of its walls, changes in the normal dimensions inside its cavities, and its location, size, etc. This greatly affects the accuracy of the prognosis and the selection of appropriate treatment, not to mention the importance of timely prevention.

Doctors note that those who have celebrated their fortieth birthday require an annual scheduled examination, even in the absence of objective symptoms and prerequisites for cardiac problems. This is explained by the increasing risk of complications in the functioning of the main “motor” of the body with age. In other cases, it is enough to visit a doctor for this procedure once every 1-2 years.

Types of diagnostics

There are several methods and types of electrocardiographic examination of the heart (ECG):

At rest. Standard method used in most cases. If the diagnosis at this stage does not provide accurate data, they resort to other types of ECG.
With load. This type of examination involves the use of physical (bicycle ergometry, treadmill test) or medicinal load. This also includes inserting a sensor through the esophagus to electrically stimulate the heart. This technique makes it possible to identify diseases that are not detected at rest.
. A small device is installed in the chest area, which monitors cardiac activity throughout the day. Heart function is recorded during everyday activities, which is one of the advantages of the study.
Transesophageal ECG performed with low information content of electrocardiography through the chest wall.

Indications for testing

You should contact the clinic for examination if:

complaints of pain in the thoracic region, including the spine;
over 40 years of age;
episodes of varying degrees and intensity of pain in the heart, especially those arising from temperature changes;
shortness of breath;
chronic respiratory system diseases;
, and a number of other cardiac pathologies;
fainting, episodes of increased heart rate, dizziness, disruption of the heart muscle.

A specialist will tell you about the indications for the ECG procedure in the video below:

Contraindications for

There are no special contraindications that could cause refusal to perform an ECG. Difficulties in carrying out the procedure are observed only in certain categories of citizens (high degree of hair growth, obesity, chest injuries). The data is distorted in persons with an installed pacemaker.

There are a number of contraindications for performing a stress ECG (an electrocardiogram is performed under load):

worsening the course of existing diseases,
myocardial infarction in the acute period,
acute infections,
(heavy).

If a transesophageal ECG is necessary, then contraindications are, accordingly, pathologies of the esophagus.

Safety of the procedure

The cardiogram is completely safe, even for pregnant women. It never gives any complications, including those related to the development of the child.

How to prepare for a cardiac ECG

No special preparation is required before the test.

You can take food and water without restricting yourself in front of it.
But you should give up energy drinks, including coffee.
It is also better to leave cigarettes and alcohol aside before the examination so as not to distort the data.

How does the session work?

To conduct an electrocardiogram, you do not need to be in a hospital; you just need to visit a clinic. In case of emergency hospitalization, the initial examination can be carried out immediately on the spot, which will allow the ambulance team to effectively help the victim.

In the diagnostic room, the patient must take a supine position on the couch.
To ensure good conductivity, skin areas on the chest, ankles and hands are wiped with a damp sponge.
After this, a pair of electrodes in the form of clothespins are placed on the arms and legs, and 6 “suction cups” are placed on the left chest area in the projection of the heart.
After this preparation, the device turns on and the electrical activity of the heart muscle begins to be recorded on a special thermal film in the form of a graphic curve. Sometimes the result goes through the device directly to the doctor’s computer.

Throughout the entire period of the study, which usually lasts no longer than 10 minutes, the patient does not feel any discomfort, everything passes in a calm state and without discomfort. After this, all that remains is to wait for the received data to be decrypted. This procedure is also performed by a doctor, and then he transmits the results to the treating doctor’s office or directly into the hands of the visitor. If pathologies requiring immediate treatment are identified, he may be sent to a hospital, but if there are none, the patient is sent home.

Read on to learn how to decipher an ECG of the heart.

Results and their interpretation

After receiving the results of the study, it is necessary to decipher the cardiac electrocardiography (ECG) indicators in children and adults. The result of the cardiogram includes several main components:

Segments ST, QRST, TP- this is the name of the distance located between the nearest teeth.
Prongs- these are acute angles, including those directed downwards. These include the designations R, QS, T, P.
Interval. It includes the entire segment and tooth. This is PQ, that is, the interval, the period of passage of the impulse from the ventricles to the atria.

The cardiologist analyzes these components; they also help determine the time of contraction and excitation of the myocardium. An ECG can determine the approximate location of an organ in the chest, which is possible due to the presence of an electrical axis.

The main indicators of the ECG diagnostic norm and their interpretation in adults are expressed in the table. It is worth noting that in some cases they change slightly. Often such deviations do not indicate the presence of pathology and are also considered normal.

Indicators of segments and teeth	Norms
	Women/men	Children
Heart rate	From 60 to 80 beats/min	110 beats/min (up to 3 years); 100 beats/min (up to 5 years); 90-100 beats/min (up to 8 years); 70-85 beats/min (up to 12 years).
T	0.12-0.28 s	-
QRS	0.06 s – 0.1 s	0.06 – 0.1 s
Q	0.03 s	-
PQ	0.12 s – 0.20 s	0.2 s
P	0.07 s – 0.11 s	Up to 0.1 s
QT	-	Up to 0.4 s

Now let's talk about the price of electrocardiography (ECG) of the heart.

Average cost of the procedure

The cost of a cardiac ECG varies depending on the city where the procedure is performed and the medical center. The average price point is 500 rubles.

The following video will talk in more detail about ECG standards:

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

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

Brief information about the ECG procedure

Electrocardiography studies the electrical currents generated by the human heart. This method is quite simple and accessible - these are the main advantages of the diagnostic procedure, which has been carried out by doctors for quite a long time and doctors have accumulated sufficient practical experience in interpreting the results.

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

Cardiogram value

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

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

Important! Doctors recommend doing a cardiogram if the patient experiences obvious changes in heart rhythm, suffers from sudden shortness of breath, weakness, or faints. It is necessary to do a cardiogram in case of primary pain in the heart, as well as in those patients who have already been diagnosed with abnormalities in the functioning of the organ and who experience murmurs.

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

What are the results of the study?

The results of the study will be absolutely incomprehensible to dummies, so you cannot read a heart cardiogram yourself. The doctor receives from the electrocardiograph a long graph paper with curves printed on it. Each graph reflects an electrode attached to the patient's body at a certain point.

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

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

Decoding the research results: main aspects

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

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

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

Table of normal values and other indicators

To interpret the ECG, there is a table containing the normal values. Based on it, doctors can see deviations. As a rule, in the process of long-term work with cardiac patients, doctors no longer use a table at hand; in adults, they have learned the norm by heart.

Indicator Normal amplitude, cQRS from 0.06 to 0.1 Mot 0.07 to 0.11 Q from 0.07 to 0.11 T from 0.12 to 0.28 PQ from 0.12 to 0.2

In addition to the table values, doctors also consider other parameters of the heart:

rhythm of heart contractions - in the presence of arrhythmia, i.e. disruptions in the rhythm of contractions of the heart muscle, the difference between the indices of the teeth will be more than ten percent. People with a healthy heart have a normosystole, but pathological data make the doctor wary and look for abnormalities. The exception is sinus arrhythmia in combination with sinus rhythm, as often happens in adolescence, but in adults, sinus rhythm with deviations indicates the onset of the development of pathology. A striking example of deviations is extrasystole, which manifests itself in the presence of additional contractions. It occurs with cardiac malformations, myocardial inflammation, ischemia,
Heart rate is the most accessible parameter; it can be assessed independently. Normally, in one minute there should be from 60 to 80 complete cycles of the heart. With an accelerated cycle, more than 80 beats indicate tachycardia, but less than 60 is bradycardia. The indicator is more illustrative, since not all severe pathologies give rise to bradycardia or tachycardia, and in isolated cases, the ECG of a healthy person will also show such phenomena if he is nervous during electrocardiography.

Heart Rate Types

An electrocardiogram shows another important parameter - the type of heart rhythm. It refers to the place from which the signal travels, causing the heart to contract.

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

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

Atrioventricular rhythm occurs in the node of the same name. The pulse rate with this type of rhythm falls below 60 beats/min, which indicates bradycardia. The causes of atrioventricular rhythm are a weak sinus node, taking certain medications, and blockage of the AV node. If tachycardia occurs during atrioventricular rhythm, this is evidence of a previous heart attack, rheumatic changes, and such a deviation appears after cardiac surgery.

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

When deciphering the analysis, doctors pay attention to the electrical axis. It is reflected in degrees and demonstrates the direction of the moving impulses. The norm for this indicator is 30-70 degrees when tilted to the vertical. Deviations from the norm suggest intracardiac blockades or hypertension.

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

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

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

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

Important! A borderline ECG of the heart indicates a deviation of some parameters from the norm. This output is generated by the electrocardiograph system and does not mean serious violations. When receiving such data, patients should not be upset - they just need to undergo additional examination, identify the cause of the disorders and treat the underlying disease.

Myocardial infarction on ECG

An ECG during myocardial infarction records extremely important diagnostic data, which can be used not only to diagnose a heart attack, but also to determine the severity of the disorders. The manifestation of pathology on the ECG will be noticeable already when the symptoms of a crisis begin. There will be no R wave on the millimeter tape - this is one of the leading signs of myocardial infarction.

Probably every adult has encountered such an examination method as an ECG at least once in his life. Many people know that this abbreviation stands for “electrocardiogram” and with its help the heart rhythm is recorded. At this point, perhaps, for most patients, all knowledge ends and on the resulting tape they see nothing but a broken line.

For particularly curious people who want to find out about the state of their health before visiting a specialist, we will try to figure out how the ECG is deciphered and what can be learned from it.

Moreover, on our website you can always get advice from a qualified cardiologist who can interpret the data on the ECG tape in detail and accurately.

ECG is not only a modern, but also the most accessible method for determining the characteristics of heart activity. Thanks to portable devices, the procedure can be carried out and read in almost extreme conditions: on the street, at home, in an ambulance or in other transport, and it only takes 5-7 minutes.

Indications for this procedure can be any unpleasant sensations that appear in the chest, with “echoes” of pain in the back, left arm, or abdominal cavity. In addition, a doctor of any specialization can refer a patient for an ECG as part of a routine examination or if he has:

severe shortness of breath;
hypertension;
interruptions in heart rhythm or murmurs;
frequent fainting (or after a single incident);
causeless weakness;
swelling of the limbs, etc.

Patients who have had a heart attack or stroke must undergo examination as prescribed by the attending physician. In some cases, it is necessary to record indicators of daily heart function or with loads. And in order to prevent disruptions in the functioning of the organ, even a healthy person should undergo an electrocardiography procedure at least once every 1-2 years.

Can you write down the heart?

To understand how to decipher a cardiogram, you should learn a little about the principle of operation of the human heart and the method of taking an ECG.

On the wall of the right atrium is the sinus node, from which the propagation of impulses normally begins. Passing through the muscles of the atrium, the excitation reaches the atrioventricular node, then into the bundle of His and along its legs the impulse spreads through the tissues of the ventricles. All this causes the 4 sections of the heart to contract. It is this pattern of excitations that is normal and gives rise to sinus rhythm.

As is known, the human body has electrical conductivity, so the biocurrents of the heart can be projected onto its surface and recorded using ECG machines.

From a physics point of view, an electrocardiogram is nothing more than a recording of electrical signals, which is carried out from several areas of the heart muscle. To do this, plates are attached to certain points of the body, transmitting signals to an ECG machine.

In practice, 3 standard bipolar leads (I, II, III), 3 reinforced unipolar leads (aVR, aVL, aVF), which are attached to the limb, and 6 reinforced unipolar chest leads (V 1 -V 6), are used. But, despite the simplicity of their arrangement, only a trained physician can attach the electrodes correctly, otherwise the ECG results will be incorrect. Less commonly used are three more leads (V 7 -V 9), which provide more accurate information about abnormalities in the myocardium of the posterior wall of the left ventricle.

From the video below you can learn more about the propagation of impulses in the heart and the correct application of electrodes when conducting an ECG.

Teeth and intervals

All received electrical signals are converted into graphic information and applied to a special tape, which is divided into squares with an area of 1 mm 2. Thus, we see the entire process of our heart’s work as a curve with pronounced teeth; for convenience, they have their own “names”: P, Q, R, S, T.

Each tooth reflects certain actions of the heart muscle and their duration:

P – excitation of the right and then the left atrium, united by one tooth (not less than 0.12 s.);
Q – excitation of the interventricular septum (0.03 s);
R – excitation of the apex of the heart with the adjacent area (0.05 s.);
S – excitation of the base of the organ (0.02 s.);

The Q, R, S waves are considered as a single ventricular complex (0.10 s.).

T - this wave reflects repolarization, that is, restoration of the original state of all parts of the heart.

The teeth form corresponding segments and intervals between themselves.

When deciphering a cardiogram, specialists usually adhere to a certain sequence.

Heart rate and frequency

Normally, the rhythm should be sinus, that is, the impulse “originates” in the sinus node. This will be indicated by the P wave, which should precede the QRS complex and be positive in all leads except aVR. If this is not the case, then we can talk about heart pathology. In case of weakness of the sinus node, the pacemaker may be the atrioventricular node, His bundles or Purkinje fibers. This information can be indicated by the functional diagnostician on the ECG tape. In addition, the heart rate (HR) is indicated there, which, however, can be calculated independently. To do this, it is enough to find out at what speed the ECG was recorded and find out the R-R distance (count the number of small squares between them).

If the recording speed is 25 mm/s, then it should be calculated using the following formula:

Heart rate= 60/R-R*0.04;

If – 50 mm/s, then heart rate = 60/R-R*0.02;

For an adult, the normal heart rate is 60-90 beats per minute. For children, all cardiogram indicators change and “grow” with them. For example, the frequency varies from 110 in the first months of life to 90 beats in adolescence.

If the rhythm is rapid, then this indicates tachycardia, if it is slow, then this indicates bradycardia, and if the R-R distance is unequal, then this condition is called arrhythmia.

The figure shows examples of normal heart rhythm (a), tachycardia (b), bradycardia (c) and irregular rhythm (arrhythmia) of an adult (d).

Electrical axis of the heart

Next, the specialist pays attention to the location of the EOS. It can not only be normal, but also have a vertical, horizontal orientation, or be deviated to one side. This indicator may depend on several factors at once - tall height, excess weight, age, pregnancy, etc., so you should not immediately and unambiguously draw conclusions about abnormalities in the functioning of an adult’s organ. However, as well as ignoring the changes, especially if the axis shift occurred quite sharply. This may indicate problems with the respiratory system, the development of heart disease, changes in the myocardium, atherosclerosis, etc. In this case, an additional examination of the patient will be prescribed.

When reading an ECG, the following algorithm is used to determine EOS.

Teeth and Spacing Analysis

ECG analysis is not complete without monitoring waves and intervals. It all starts with the P wave, which, as mentioned above, should be sinus. If it has an increased amplitude or duration in the second lead, then this may indicate hypertrophy of the right or left atrium, respectively. Further, by assessing the PQ interval, it is possible to identify blockade of the atrioventricular node, which is characterized by an increased duration of the PQ interval or its complete absence.

A separate point in ECG analysis is reading the QRS complex. Normally its duration is 60-100 ms. Its lengthening is evidence of conduction disturbances in the bundle branches. Below are examples of ECG sections where right and left bundle branch blocks are clearly visible.

Moreover, a Q wave whose depth exceeds 1/3 of the R wave may indicate myocardial infarction.

The QT interval reflects the duration of ventricular contraction and is 390-450 ms. Its lengthening indicates the development of coronary heart disease, and its shortening indicates hypercalcemia. The ST segment normally should not rise above the isoline by more than 1 mm and decrease by more than 0.5 mm. Violation of the first condition indicates an acute infarction or pericarditis, and the second – of ischemia.

The video shows the sequence and more detailed interpretation of all the teeth of the ECG intervals:

But no matter how detailed such information is presented, it should be understood that only a specialist can correctly interpret the cardiogram.

The ruler is an indispensable assistant

Sometimes it happens that a person’s life depends on precious minutes, during which the doctor must understand the reason for the deterioration of the patient’s condition and take appropriate measures. Ambulance paramedics sometimes have to make a diagnosis right at the patient’s home, relying only on electrocardiography readings. Of course, analysis in such a situation must be carried out extremely quickly and at the same time correctly. For such emergency cases and to help medical students, a ruler was developed to interpret the resulting ECG.

With its help, you can quickly read an ECG: determine the heart rate, measure and compare intervals and their duration with the norm, and also determine EOS. An invention such as a ruler can also become useful when trying to independently decipher an ECG.

Other ways to look into the “engine” of the human body

In addition to the electrocardiogram, modern medicine has such methods of examining the heart as echocardiography and the method of 24-hour heart rate monitoring.

Holter method

This method allows you to obtain continuous data on heart function for 24 hours (and sometimes even up to 7 days). Daily monitoring allows you to identify pathologies that are determined in special conditions. To do this, 2 or 3 electrodes (rarely more) are attached to the patient’s body, and a recorder is worn on a belt or over the shoulder, which keeps continuous recording. In this case, the subject leads a normal lifestyle, with usual physical activity, recording the time and circumstances in which the unpleasant sensations appeared.

Recorders are divided into those that record on magnetic media and those that have digital memory. The analysis of the accumulated information is carried out on a computer with software installed for this purpose, but it cannot be done without correction of the results by a specialist. The conclusion on daily monitoring of heart function contains the same mandatory points as in a regular ECG. Only information about health is added, according to the diary, prescribed loads and related changes.

Echocardiogram

Like any organ, the heart is subject to ultrasound examination. The doctor performing the procedure sees a real-time video of the beating heart on the screen. Like regular ultrasound, echocardiography is absolutely painless and has no contraindications. An echocardiogram may be prescribed if the patient:

Heart murmurs;
Signs of ventricular failure;
IHD in chronic or acute form;
Chest injuries;
Suspicion of an aortic aneurysm or other vascular abnormalities, etc.

During echocardiography, a functional diagnostician can determine:

Condition of all heart valves;
The dimensions of all chambers of the heart and the thickness of their walls;
The direction of blood flows and their speed;
Pulmonary artery pressure.

To identify hidden pathologies or abnormalities that are not diagnosed at rest, the patient may be assigned certain loads during echocardiography. This is called a stress echo.

As practice shows, three factors can affect the results of echocardiography:

Patient characteristics, for example, obesity, specific location of the heart, chest deformity, emphysema.
Experience and qualifications of a functional diagnostician.
Ultrasound device class.

Therefore, final conclusions about heart health cannot be drawn or diagnoses made based on echocardiography results alone. This procedure is usually prescribed in combination with electrocardiography.

Conclusions

This article is more for informational purposes only, because only a cardiologist who has been studying the heart for many years can read an electrocardiogram correctly. Thus, each person will be able to determine from the tape whether he has a sinus rhythm, heart rate, compare the duration of intervals with the norm and, guided by the proposed algorithm, set the EOS.

But it’s worth remembering once again, if you find any abnormalities on your ECG, do not rush to make a diagnosis and take medications - wait for the doctors’ conclusion.

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

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

Figure 1. ECG tape with graphical data

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

Main tasks of electrocardiography

Timely detection of irregularities in rhythm and heart rate (detection of arrhythmias and extrasystoles).
Determination of acute (myocardial infarction) or chronic (ischemia) organic changes in the heart muscle.
Detection of disturbances in the intracardiac conduction of nerve impulses (impaired conduction of an electrical impulse through the conduction system of the heart (blockade)).
Definition of some acute (PE - pulmonary embolism) and chronic (chronic bronchitis with respiratory failure) pulmonary diseases.
Detection of electrolyte (potassium, calcium levels) and other changes in the myocardium (dystrophy, hypertrophy (increase in the thickness of the heart muscle)).
Indirect registration of inflammatory heart diseases (myocarditis).

Disadvantages of the method

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

Indications for an ECG

Electrocardiography is performed routinely or as an emergency. Routine ECG registration is carried out during pregnancy, upon patient admission to the hospital, in the process of preparing a person for operations or complex medical procedures, to assess cardiac activity after certain treatment or surgical medical interventions.

For preventive purposes, an ECG is prescribed:

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

On an emergency basis, i.e. “this minute” an ECG is prescribed:

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

Contraindications to ECG

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

Preparation for electrocardiography

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

It is necessary to know whether the patient is taking heart medications (a note must be made on the referral form).
During the procedure you cannot talk or move; you must lie down, relax and breathe calmly.
Listen and follow simple commands from medical staff, if necessary (inhale and hold for a few seconds).
It is important to know that the procedure is painless and safe.

Distortion of the electrocardiogram recording is possible when the patient moves or in case of improper grounding of the device. Incorrect recording may also be caused by loose contact of the electrodes to the skin or incorrect connection. Interference in the recording often occurs due to muscle tremors or electrical interference.

Carrying out electrocardiography or how to do an ECG

Figure 2. Application of electrodes during ECG When recording a cardiogram, the patient lies on his back on a horizontal surface, arms extended along the body, legs straightened and not bent at the knees, chest bare. One electrode is attached to the ankles and wrists according to the generally accepted scheme:

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

Then 6 more electrodes are placed on the chest.

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

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

ECG interpretation and interpretation

The electrocardiogram is deciphered by either a cardiologist, a functional diagnostics doctor, or a paramedic (in an emergency setting). The data is compared with a reference ECG. The cardiogram usually shows five main waves (P, Q, R, S, T) and a subtle U-wave.

Figure 3. Basic characteristics of the cardiogram

Table 1. ECG interpretation in adults is normal

ECG interpretation in adults, norm in the table

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

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

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

The main and most important clinical significance of the ECG is in myocardial infarction and cardiac conduction disorders. By analyzing the electrocardiogram, you can obtain information about the focus of necrosis (localization of myocardial infarction) and its duration. It should be remembered that the ECG assessment should be carried out in conjunction with echocardiography, 24-hour (Holter) ECG monitoring and functional stress tests. In some cases, the ECG may be practically uninformative. This is observed with massive intraventricular blockades. For example, LBBB (complete block of the left bundle branch). In this case, it is necessary to resort to other diagnostic methods.