How often is an ecg performed on adults? What not to do before an ecg. Is ECG taken for pregnant women?

Few people thought that preparation for an ECG even existed. This is not strange, because few doctors reported the necessary preliminary procedures. Usually the patient comes, lies down on the couch, is connected to the device and is diagnosed. And often the results of such a cardiogram are unpredictable. An ECG is needed to obtain information about the functioning of the heart. For a long time, doctors have been using this research method to prevent possible complications in the functioning of this organ. Carrying out electrocardiography is quite simple, but following basic rules contributes to the accurate outcome of the examination.

Preparatory stages

The attending physician must describe in detail to the patient all necessary actions before taking an ECG. For men with abundant body hair, it is better to shave it off - this will allow for closer contact between the electrodes and the body. The day before the scheduled procedure, you need to take a warm shower. The same should be done the morning before. Clean skin is better suited for attaching electrodes. If the contact is close enough, the likelihood of interference will decrease dramatically. Be sure to carry out a water procedure after the session. This is due to the application of a special gel to the attachment points for better current conductivity. For people who are sensitive to cleanliness, it is better to bring a towel and a sheet. It's just worth remembering how many patients are on the couch in a day.

The main requirement for the human condition is calm. If before a cardiac examination a person has been subjected to intense physical activity, anxiety or stress, it is necessary to come to a state of rest. It is better to relax while sitting in a comfortable position. It is useful to do breathing exercises during this. You can allocate time for this while waiting in line.

It is advisable to choose loose-fitting, easy-to-remove clothing for visiting a cardiologist. This will speed up the event process.

When the examination period occurs during cold weather, the ECG room should be warm and comfortable. If a person gets cold, this can negatively affect the electrocardiogram.

Women should not use cream so as not to leave a greasy mark on the skin. This prevents the device from being tightly attached to the body.

What should you not take before the test?

A person should give up all tonic drinks. The list includes tea, coffee, energy cocktails, and especially those containing alcohol. This should be done no later than 4-6 hours before the start of the procedure. This does not apply to alcohol. You should not drink it for at least several days before the procedure. Energy drinks, which contain a considerable dose of caffeine, not only distort cardiograph readings, but also negatively affect the functioning of many organs.

It is not recommended to eat heavy or fatty foods for an hour before the procedure. Eating spicy and salty foods is also not advisable. Large meals may cause shortness of breath and interfere with monitoring results. If skipping breakfast for some reason is not recommended or you simply don’t feel like it, you can have a light snack in small quantities.

Vasoconstrictor drugs are also contraindicated before the start of the session. Eye drops and nasal sprays are not used before the cardiogram procedure.

Just like stimulants, strong sedatives are also contraindicated. If a patient takes such drugs, the doctor may misdiagnose bradycardia (or tachycardia in the case of stimulants).

Holter monitoring

Holter monitoring is a modern electrocardiogram method that allows it to be carried out 24 hours a day. The method is more effective than a one-time short-term procedure, the result of which can be influenced by many factors. Preparing a patient for a Holter ECG involves performing a number of simple measures. A person must understand that the study involves observing the functioning of the heart during a normal lifestyle. You need to carry on with your daily affairs, go to work and not try to influence the monitoring.

The Holter device is a small block with electrodes that are attached to the chest.

Clothing should not have metal parts. Metal jewelry will also have to be removed. Before using the device, it is necessary to carry out water procedures, since this cannot be done during the study.

During monitoring you should avoid:

caffeine (coffee, strong tea, energy drinks);
alcohol;
excessive physical activity;
swimming and bathing;
taking medications that affect cardiac function.

The application of ointments, creams and various cosmetics is undesirable. As with a regular ECG, precautions must be taken. These include taking cardiac stimulants, nervous system stimulants, and vasoconstrictors.

Our heart is a motor from which electrical impulses are sent every second. If the heart beats evenly, then impulses occur at equal intervals. The paper coming out of the ECG machine reflects the normal heart rhythm, contraction frequency, source of excitation in the heart, and conductivity. It is recommended for a healthy person to have their heart function checked once every 2 years. An ECG in early pregnancy is one of the first important procedures during registration. Further is carried out as necessary.

Read in this article

Why do they do it? Early ECG?

ECG is necessary and safe for pregnant women. The main goals of the procedure are:

Prevention of heart disease and heart failure. , arrhythmia, myocardial infarction, angina pectoris, inflammatory processes are recorded using an electrocardiogram.
Prevention of deviations in the functioning of internal organs and body systems - gestosis.
Compiling a complete picture of a pregnant woman’s health. An ECG in the card will help doctors make decisions: prescribe medications, pay attention to problems and monitor them more closely, prescribe additional examinations.
Further monitoring of fetal development and delivery. There are heart diseases in which continuing pregnancy is life-threatening for the mother in labor. She must make an informed and deliberate decision based on knowledge of the risk. There are diagnoses for which natural childbirth is prohibited; the doctor must identify them.

Is an ECG done in the early stages of pregnancy if the woman has not yet suffered from any heart disease? The volume of circulating blood pumped increases in pregnant women, so deviations associated with the new condition may occur. Hormonal changes in the body can also affect the functioning of the heart. And some diseases are asymptomatic and do not make themselves felt.

All pregnant women are required to undergo an ECG. Agree, it is extremely dangerous to discover a problem during childbirth. If heart problems were overlooked and labor began, then only resuscitation will save you.

Is ECG dangerous during pregnancy?

Electrocardiography is safe and can be done an unlimited number of times. There are no penetrating rays in the device and it has no effect on the body. The purpose of an ECG is to record electrical impulses emanating from the contraction of the heart muscle. You can go for examination without fear and additional consultations with a doctor.

The ECG procedure in early pregnancy is no different from the usual one and is performed in the supine position. Sensors are attached to the wrists and ankles, and electrodes are attached to the chest area. For a healthy person, three leads (sensor application patterns) are applied between the arms and legs, points on the chest. And for pregnant women, the doctor may prescribe additional leads for a more complete picture.

Recommendations for the procedure are standard: eat 2 hours before the test, do not worry, since nervous tension and overeating can make the result uninformative, and in the worst case, cause a false positive diagnosis.

How often should an electrocardiogram be done?

An ECG during early pregnancy can be shown more than once so as not to miss a dangerous condition. Here are the cases in which doctors refer for additional examination:

for complications: severe toxicosis, gestosis, low or polyhydramnios, high/low blood pressure, pressure surges;
with rapid heartbeat, pain in the heart area, in the left side of the chest and regular pain in the area of the left shoulder blade (be sure to tell your doctor about these symptoms!);
with frequent dizziness, darkening of the eyes;
in the presence of hectic work and other factors in the life of a pregnant woman that affect her nervous system.

If there are no complications, the procedure is performed three times. The first time is as early as possible, ideally at 5-6 weeks. If the deadline is missed - during registration. The second is carried out during general screening at the 12th week. When applying for sick leave for maternity leave, the doctor may order an ECG for the third time.

How to read an ECG in pregnant women

In the absence of deviations, the results of a pregnant woman will not differ from the results of any healthy person:

heart rate (pulse) - 60-80 beats/minute;
rhythm - sinus;
the electrical axis of the heart (heart position, EOS) is 30-70 0, but during pregnancy a temporary deviation of up to 90 0 is allowed.

If the conclusion shows different parameters, it is time to contact a cardiologist and conduct additional examinations.

A slight sinus tachycardia is allowed; it is possible to detect overload of some cardiac sections. Such deviations are associated with an increase in load and circulating blood volume. This is not a reason to panic, but a reason to dig deeper into problem areas and monitor them.

Do not confuse maternal ECG and fetal ECG

To check the heart function of the unborn baby, CTG (cardiotocography) is performed. The need for it appears when the fetal heartbeat can be registered - no earlier than 28-30 weeks.

Watch the video about performing CTG in pregnant women:

Have you ever had a case where heart disease was once detected and stopped during pregnancy using an ECG? Tell us about it in the comments!

More than a century has passed since scientists discovered the heart's ability to produce electrical impulses in small doses.

This discovery marked the beginning of the science of electrocardiology, of which electrocardiography is an integral part. This section studies the electric current that arises in the heart or affects it from the outside.

Electrocardiography is capable of recording electrical potentials that arise during relaxation and contraction of the myocardium in a certain time period.

These impulses spread throughout the body and reach the skin.

A special device - an electrocardiograph - records these potentials and produces the result in the form of a graphic image, called an electrocardiogram. It can be printed on paper or displayed on a monitor screen.

Electrocardiography can serve various purposes:

Assess the effectiveness of heart medications, pacemakers and other methods of therapy.
Identify and monitor the dynamics of the development of heart diseases such as arrhythmia, intracardiac conduction disorders (blockades) and metabolism necessary for the functioning of the heart (potassium, magnesium, calcium). Here you can determine myocardial damage, the physical condition of the organ, acute cardiac pathologies and non-cardiac diseases (for example, pulmonary embolism).

An ECG is a very simple procedure with virtually no contraindications. It is allowed to be done to women during pregnancy and even to newborns upon discharge from the hospital. In emergency cases, a cardiogram is taken by an ambulance paramedic in a special vehicle, at the patient’s home, and even on the street.

Most often, the procedure is carried out in district clinics, hospitals, specialized clinics, and sanatorium institutions. This takes no more than 10 minutes and causes absolutely no discomfort to the subject.

However, despite all the positive aspects, electrocardiography also has disadvantages. Here, the short duration of the procedure is most often noted.

The operating principle of any electrocardiograph is based on the propagation of cardiac impulses. They are able to move by reducing the polarization of the cell electrodes. At rest, the surfaces of all muscle cells of the heart have a positive charge.

At such a moment there is no potential difference and, accordingly, it is impossible to register the electric field.

Electrical impulses in the heart usually originate in the sinoatrial (sinus) node.

It is located near the superior vena cava in the right atrium. The node is a specialized cell with the ability to automatically produce electrical impulses. The latter spread from the sinoatrial node first to the right, then to the left atrium.

The result of the propagation of electrical signals through the atria and ventricles is their contraction. The result is the flow of blood to the lungs and into the circulatory system.

Heart cardiogram: recording technique and scope of application

The recording of the potential difference between two points in the electrical field of the heart by an electrocardiograph is called a lead.

When recording a cardiac cardiogram, standard leads are recorded from two limbs by alternately connecting paired electrodes. Three standard positions form a triangular figure (Einthoven triangle).

A cardiac cardiogram is recorded when the patient is at rest. In some cases, the specialist records the ECG during inspiration, asking the patient to take a deep breath.

When analyzing ECG results, the cardiologist must have the necessary knowledge and skills to interpret the graphic image.

Electrocardiography is prescribed not only for existing or suspected heart disease. Your doctor may recommend an ECG as a preventative measure, as well as during a medical examination and annual physical examination.

If there are no suspicions of abnormalities, a cardiac cardiogram is done upon receipt of a medical book for employment. Children are given an ECG upon admission to kindergarten, and according to the new rules, they are required to provide it to the head of the sports section and the children involved in it. In addition, ECGs are often performed on pregnant women before giving birth. Patients with diabetes mellitus must be examined without fail, even in the absence of indications.

The referral for the study is given by the attending physician or cardiologist. Indications for an urgent procedure include pain in the heart, fainting, dizziness, hypertension, swelling of the legs, and weakness in the joints.

Electrocardiography: types of diagnostics

The first device capable of recording a high-quality ECG was a string galvanometer designed by V. Einthoven. Its basis was a very thin thread, which was in a magnetic field under a certain voltage. He created a new direction in the physiology of blood circulation - electrophysiology of the heart.

The first such equipment was very bulky and weighed 270 kg.

V. Einthoven identified the main waves, intervals and segments of the ECG, and also calculated their time intervals. He also proposed a system for placing electrodes on the surface of the patient’s body. These data are used by cardiologists to this day.

The jagged edges are the ups and downs of a graph.. In electrocardiography, a segment is a section of a straight line between two teeth. An electrocardiogram can show cardiac dysfunction in the early stages, as well as consider the possibilities for the development of serious pathologies.

However, an ECG does not always accurately determine the presence of a disease. For example, a disturbance in the rhythm of the heart (arrhythmia) during a study at rest may “lurk” and not manifest itself.

Therefore, the specialist chooses another examination method, there are several of them:

At rest- The standard method used most often. The patient lies on the couch in a relaxed state.
With load— during this procedure, the doctor will first take electrocardiograph readings, then ask the patient to perform a simple physical exercise (bending, squats), and then examine him again using the device. In addition, it is possible to use other methods - bicycle ergometry and treadmill test. In the first case, a bicycle ergometer is used (a device similar to an exercise bike with varying resistance of the pedals), in the second, a treadmill (a moving track). For each type of examination, electrodes connected to a computer are applied to the patient's body. The doctor monitors and analyzes the readings during the procedure.
Daily (Holter) monitoring- This method takes the longest time. When using it, adhesive electrodes are attached to the body of the subject. They are connected to a device that is attached to the belt or worn over the shoulder on a belt. It weighs no more than half a kilogram, so it does not cause any particular inconvenience.

The patient should keep a diary in which he indicates information about changes in physical activity, emotional overload, time of taking medications, sleep and wakefulness. Here he describes pain in the heart area and a feeling of discomfort that can arise during certain activities.

There are two options for Holter monitoring: full-scale and fragmented.

The first continues continuously for 1-3 days, as a result providing accurate and complete information about abnormalities in the functioning of the heart.

Fragmented monitoring may extend over a longer period. It is resorted to only when cardiac dysfunction occurs infrequently. Electrocardiography in this case is carried out using a special device.

To record deviations, the subject turns on the ECG recording button when pain occurs. The apparatus for such research is very miniature: it can be a pocket version or a device in the form of a wristwatch.

A sterile electrode is inserted into the subject's esophagus. This is usually done through the nasopharynx, less often through the mouth. The patient must make swallowing movements. But do not be alarmed - the transesophageal electrophysiological examination of the heart (TECFE) probe is thin and its insertion usually does not cause difficulties. At the same time, electrodes are attached to the chest to record an electrocardiogram.

The electrode is inserted approximately 40 cm - where the heart is closest to the esophagus. After this, they begin to record a cardiogram, and the probe begins to send weak electrical signals to the heart, causing it to contract more often.

At the end of the study, the electrode is removed from the esophagus.

In electrocardiography, there are instrumental methods for studying the functioning of the heart muscle. These include, for example, phonocardiography. In this case, a special microphone records the sounds made when the heart muscle is excited and relaxed. As a rule, listening is carried out by an experienced specialist with good hearing, who is able to separate murmurs and heart sounds from pathological sounds.

The book by V.V. Murashko “Electrocardiography” contains other methods of conducting research. Its cost is low, but it will be very useful for those who want to master the basics of ECG.

How to do an ECG correctly: preparation and conduct of the procedure

For those who do not know how to do an ECG correctly, do not worry: conducting electrocardiography does not require special training. However, some nuances still exist. It is advisable to refrain from eating heavy food 2 hours before the procedure.

Also, do not be nervous, play sports, drink energy cocktails or alcohol, as well as strong coffee or tea. Before the examination, women do not need to apply lotion or cream to the body; they should remove any jewelry from the wrists and chest area: bracelets, rings, chains, etc.

The chest electrodes have a special suction cup that is attached to the body due to the vacuum created. The specialist taking the readings knows very well how to do an ECG correctly, so it is unlikely that he will be able to confuse the wires connecting the suction cups to the device.

Before starting work, the device must be warmed up (3-5 minutes is enough). After this, the position of the recorder pen is adjusted, giving a calibration signal by turning on a special button.

There are no contraindications for conducting an ECG - the study can be performed even on infants.

In this case, the procedure for collecting data from a child is similar to that carried out by adults. Only the result will be different - for example, babies have a higher heart rate.

Some children are afraid of all people in white coats, so they can be very nervous before the procedure. Before it starts, parents should relieve stress in their children - give them a favorite toy, show a funny picture or photo (you can do it on your phone). An older child can be told about the study in advance and shown in a playful way how to do an ECG correctly.

The examination procedure may be difficult for those with complex chest injuries, high obesity, or excessive chest hair - in this case, the electrodes will not adhere tightly to the skin and the examination result will be distorted. The presence of a pacemaker will also lead to incorrect results.

Transesophageal examination cannot be performed in the presence of tumors or other diseases of the esophagus. ECG with stress is contraindicated in acute infectious diseases, chronic heart failure, coronary heart disease, complex rhythm disturbances, and in the acute period of myocardial infarction. Also, you should not do this if there is an exacerbation of diseases of other body systems - urinary, respiratory, digestive.

Normal cardiogram of a healthy heart and what it looks like

In a healthy adult, a normal cardiogram (cardiogram of a healthy heart) is considered to be a curve with sinus rhythm.

The heart rate (HR) is 60-80 beats per minute, the EOS (electrical axis of the heart) is in the standard position.

PQ interval (period of the excitation wave passing through the atria and atrioventricular node to the ventricular myocardium) - 0.12-0.18 seconds. (up to 0.2).

No changes in rhythm or tone (arrhythmia, bradycardia, tachycardia) were detected.

Increased heart rate is possible in pregnant women or overly emotional individuals. In elderly patients, on the contrary, there is a slowing of the heart rate or morphological pathologies of the myocardium.

Only a specialist with a medical education can correctly decipher the cardiogram and describe the obtained ECG parameters.

Electrocardiography can accurately diagnose various diseases of the cardiovascular system - ischemia, abnormalities in the development of conduction pathways, cardiac aneurysm, extrasystole, angina pectoris and many others.

The most serious diagnosis with electrocardiography is myocardial infarction. It is here that you can first detect areas of damaged or dead tissue, determine the specific location (in which wall of the heart) and the depth of the lesion. An ECG easily distinguishes the acute phase of a heart attack from old scars and aneurysms.

In case of a heart attack, the ECG procedure is performed more than once. The first time this happens is during the first contact with the patient - at home, in an ambulance or in a hospital waiting room. If there are no changes in the graphic image, but if symptoms are present, the procedure is repeated after 6 hours - by this time the symptoms usually appear in full force.

After this, diagnostics are carried out daily, and during recovery - once every few days. Thus, over the entire period the patient is examined at least 10 times.

The patient must always remember that taking care of his health should only be entrusted to a specialist. This fully applies to the electrocardiography procedure. You should not neglect the doctor’s prescription and you should not try to decipher the ECG yourself, even if you are sure that the result will be a normal cardiogram.

A cardiogram of a healthy heart, like an ECG with abnormalities, can only be read correctly by a doctor.

Only a person with a medical education is capable of assessing the risk of a critical condition obtained from the examination, clinical symptoms and the results of the study. Otherwise, there is a possibility of underestimating the ECG, which can lead to fatal consequences.

Electrocardiography is the recording of bioelectric potentials that occur during contraction of the heart muscle. This method is accessible, does not require special preparation, and is safe for the patient. At the same time, the information received by the doctor can help in making a diagnosis of coronary artery disease, arrhythmia, and conduction disorders.

Read in this article

Operating principle of an electrocardiograph

An ECG recording device consists of electrodes that are attached to the patient's body, a galvanometer, an amplifier, a recorder and a lead switch. The impulses that are formed in the heart muscle must first be amplified, then they are perceived by the galvanometer. It converts electrical waves into mechanical vibrations.

The recorder records, using thermal paper recorders, a typical graphical curve called an electrocardiogram.

Using an ECG study, you can judge the condition of the heart muscle by the following indicators:

impulse conductivity;
rhythm of heart contractions;
enlargement of one or more parts of the heart;
blood supply to the myocardium;
areas of necrosis (infarction) their size, depth and duration of occurrence.

Clothing is selected in such a way that it is easy to attach electrodes to the skin of the ankles, wrists and chest.

On the day of the study, drinking alcoholic beverages and smoking is strictly prohibited; you must avoid sports and a hearty breakfast. The best drink to drink is plain drinking water, weak tea or fruit juice.

To take an electrocardiogram, the patient is placed on a couch and a healthcare professional places electrodes on the legs, wrists and chest. If there is difficulty breathing in a horizontal position, the procedure is performed while sitting.

Rules for the procedure

To ensure good contact between the skin and the electrode, the attachment site is degreased with ethyl alcohol and a special conductive gel is applied. After this, readings are taken using an ECG diagnostic device.

The whole procedure takes about 10 - 15 minutes.

In order to get a reliable result, you need to be in a calm, relaxed state, and not hold your breath. Muscle tremors from excitement or cold can lead to data distortion.

The generally accepted leads are 3 standard, 3 reinforced and 6 chest. Each lead will record at least 4 cardiac cycles. After this, the device is turned off, the electrodes are removed, and the functional diagnostics doctor is given a signed tape, which he must decipher.

For information on the ECG recording method, watch this video:

Are there any special features during pregnancy?

In the body of a pregnant woman, the load on the heart muscle changes, as it must provide blood supply to the fetus in the uterus. The electrocardiogram may show abnormalities that are not an indication of heart disease.

Therefore, starting from 3 - 4 months, when deciphering the testimony, an amendment is made for the presence of the gestation process.

When preparing and conducting the procedure itself, standard research techniques are used.

How to do an ECG for women

For women, the rules for installing electrodes are the same as for men. They should be located in the heart area, directly on the skin, so before performing an ECG, you must completely remove all clothing from the chest, including your bra. Please note that tights or stockings will interfere with attaching the sensors to the lower leg.

Interpretation of ECG indicators

On the tape, the curve obtained after taking the cardiogram has 5 teeth. They occur with sequential contraction of the atria and ventricles. The following designations are accepted:

The P wave is an indicator of the work of the right (first half) and left atrium.
P Q – interval of impulse passage to the ventricle along the Hiss bundle.
QRST - complex occurs during contraction of the ventricles, while the highest R wave reflects the excitation of the ventricular myocardium, and Q and S are the partitions between them, T - occurs during the period of myocardial recovery after systole.

Teeth and intervals

Normal in adults

A doctor can fully evaluate the electrocardiogram, since making a diagnosis requires knowing the symptoms of the disease and data from other research methods (blood tests, ultrasound, echocardiography). The general characteristics that a specialist evaluates in a healthy person are as follows:

The rhythm of contractions is from 60 to 80 per minute.
The size of the intervals should not exceed normal values, or be shorter than average values.
– normally R exceeds S in all leads except aVR, V1 - V2, sometimes V3.
The ventricular complex is no more than 120 ms.
T is positive and longer than the QRS complex.

ECG (normal)

During pregnancy

As the uterus grows, it raises the dome of the diaphragmatic septum and after 24 - 24 weeks the apex of the heart moves to the left. This is reflected in the electrocardiogram by an increase in the amplitude of R in the first lead, and S and Q in the third lead, the ventricular complex decreases along with the ST segment. Changes in conduction through the heart muscle are also associated with the influence of hormones produced by the placenta.

Characteristic features:

Shift of the heart axis to the left.
T biphasic and negative in the right chest leads.
The ventricular complex is wider than normal.
Rapid rhythm, single extraordinary contractions.

Respiratory arrhythmia in pregnant women

Deviations that the device can detect

By taking and interpreting an electrocardiogram, you can identify signs of the following diseases:

angina pectoris and heart attack;
type of arrhythmia, location of the pacemaker;
blockade due to decreased conductivity;
myocardial hypertrophy and its localization;
signs of myocarditis and pericarditis;
pulmonary embolism;
symptoms of pulmonary hypertension;
disorders of the electrolyte composition of the blood.

3rd degree AV block

Disadvantages of ECG examinations

Despite its high diagnostic value, a regular ECG cannot detect changes in heart function outside the time of its taking. Therefore, along with the traditional technique, the patient may be prescribed additional exercise tests.

Using this method, it is impossible to recognize heart murmurs, therefore, if structural defects of the valves or septa are suspected, phonocardiography or ultrasound of the heart should be performed.

If you plan to install a stent or shunt for myocardial ischemia, then it is required to determine the localization of the narrowing of the coronary arteries. Tumor processes are diagnosed by X-ray or MRI examination.

Current patient questions

The ECG method is traditional and has been used for a long time in medical practice. But patients often have concerns about its use. The most common questions:

Thus, an ECG is a time-tested, accessible type of diagnosis, which is used both for preventive examination during clinical examination and for making a diagnosis in the presence of complaints of cardiac dysfunction. Such research is safe and informative.

Patients want to know...

Yes, patients want to know what the strange teeth on the tape left by the recorder mean, so before going to the doctor, patients want to decipher the ECG themselves. However, everything is not so simple and in order to understand the “sophisticated” record, you need to know what the human “motor” is.

The heart of mammals, which includes humans, consists of 4 chambers: two atria, endowed with auxiliary functions and having relatively thin walls, and two ventricles, which bear the main load. The left and right parts of the heart are also different. Providing blood to the pulmonary circulation is less difficult for the right ventricle than pushing blood into the systemic circulation with the left. Therefore, the left ventricle is more developed, but also suffers more. However, regardless of the difference, both parts of the heart must work evenly and harmoniously.

The heart is heterogeneous in its structure and electrical activity, since contractile elements (myocardium) and non-contractile elements (nerves, vessels, valves, fatty tissue) differ from each other in varying degrees of electrical response.

Typically, patients, especially older ones, worry about whether there are signs of myocardial infarction on the ECG, which is quite understandable. However, to do this you need to learn more about the heart and the cardiogram. And we will try to provide this opportunity by talking about waves, intervals and leads and, of course, about some common heart diseases.

Heart Abilities

We first learn about the specific functions of the heart from school textbooks, so we imagine that the heart has:

Automatically, caused by the spontaneous generation of impulses, which then cause its excitation;
Excitability or the ability of the heart to activate under the influence of exciting impulses;
or the “ability” of the heart to ensure the conduction of impulses from the place of their origin to the contractile structures;
Contractility, that is, the ability of the heart muscle to contract and relax under the control of impulses;
Tonicity, in which the heart does not lose its shape in diastole and ensures continuous cyclic activity.

In general, the heart muscle in a calm state (static polarization) is electrically neutral, and biocurrents(electrical processes) are formed in it under the influence of exciting impulses.

Biocurrents in the heart can be recorded

Electrical processes in the heart are caused by the movement of sodium ions (Na+), which are initially located outside the myocardial cell, into it and the movement of potassium ions (K+), rushing from inside the cell to the outside. This movement creates the conditions for changes in transmembrane potentials throughout the entire cardiac cycle and repeated depolarizations(excitation, then contraction) and repolarizations(transition to the original state). All myocardial cells have electrical activity, but slow spontaneous depolarization is characteristic only of the cells of the conduction system, which is why they are capable of automatism.

Excitement spreading through conducting system, sequentially covers the parts of the heart. Starting in the sinoatrial (sinus) node (the wall of the right atrium), which has maximum automaticity, the impulse passes through the atrial muscles, the atrioventricular node, the bundle of His with its legs and is directed to the ventricles, stimulating parts of the conduction system even before the manifestation of its own automaticity .

Excitation that occurs on the outer surface of the myocardium leaves this part electronegative in relation to areas not affected by excitation. However, due to the fact that body tissues have electrical conductivity, biocurrents are projected onto the surface of the body and can be recorded and recorded on a moving tape in the form of a curve - an electrocardiogram. The ECG consists of waves that are repeated after each heartbeat, and through them shows the disorders that exist in the human heart.

How is an ECG taken?

Many people can probably answer this question. Doing an ECG, if necessary, will also not be difficult - there is an electrocardiograph in every clinic. ECG technique? It only seems at first glance that it is so familiar to everyone, but meanwhile, only medical workers who have undergone special training in taking an electrocardiogram know it. But we hardly need to go into details, since no one will allow us to do such work without preparation anyway.

Patients need to know how to properly prepare: that is, it is advisable not to overeat, not to smoke, not to drink alcoholic beverages and medications, not to get involved in heavy physical labor and not to drink coffee before the procedure, otherwise you can fool the ECG. It will certainly be provided, if nothing else.

So, a completely calm patient undresses to the waist, frees his legs and lies down on the couch, and the nurse will lubricate the necessary places (leads) with a special solution, apply electrodes from which wires of different colors go to the device, and take a cardiogram.

The doctor will decipher it later, but if you are interested, you can try to figure out your teeth and intervals yourself.

Teeth, leads, intervals

This section may not be of interest to everyone, in which case you can skip it, but for those who are trying to understand their ECG on their own, it may be useful.

The waves in the ECG are designated using Latin letters: P, Q, R, S, T, U, where each of them reflects the state of different parts of the heart:

P – atrial depolarization;
QRS wave complex – ventricular depolarization;
T – ventricular repolarization;
A weak U wave may indicate repolarization of the distal portions of the ventricular conduction system.

To record an ECG, 12 leads are usually used:

3 standard – I, II, III;
3 reinforced unipolar limb leads (according to Goldberger);
6 reinforced unipolar chest (according to Wilson).

In some cases (arrhythmias, abnormal location of the heart), there is a need to use additional unipolar chest and bipolar leads according to Neb (D, A, I).

When interpreting the ECG results, the duration of the intervals between its components is measured. This calculation is necessary to assess the rhythm frequency, where the shape and size of the teeth in different leads will be an indicator of the nature of the rhythm, the electrical phenomena occurring in the heart and (to some extent) the electrical activity of individual sections of the myocardium, that is, the electrocardiogram shows how our heart works at that time. or another period.

Video: lesson on ECG waves, segments and intervals

ECG analysis

A more rigorous interpretation of the ECG is made by analyzing and calculating the area of the teeth when using special leads (vector theory), however, in practice, they mainly make do with such an indicator as electrical axis direction, which is the total QRS vector. It is clear that everyone’s chest is structured differently and the heart does not have such a strict arrangement, the weight ratio of the ventricles and the conductivity inside them are also different for everyone, therefore, when deciphering, the horizontal or vertical direction of this vector is indicated.

Doctors carry out ECG analysis in a sequential order, determining the norm and violations:

Assess the heart rhythm and measure the heart rate (with a normal ECG - sinus rhythm, heart rate - from 60 to 80 beats per minute);
Intervals (QT, norm – 390-450 ms) are calculated, characterizing the duration of the contraction phase (systole) using a special formula (I often use Bazett’s formula). If this interval lengthens, then the doctor has the right to suspect. Hypercalcemia, on the contrary, leads to a shortening of the QT interval. The conductivity of the pulses reflected through the intervals is calculated using a computer program, which significantly increases the reliability of the results;
they begin to calculate from the isoline according to the height of the teeth (normally R is always higher than S) and if S exceeds R and the axis deviates to the right, then they think about disturbances in the activity of the right ventricle, if on the contrary - to the left, and the height of S is greater than R in II and III leads – left ventricular hypertrophy is suspected;
The QRS complex is studied, which is formed during the conduction of electrical impulses to the ventricular muscle and determines the activity of the latter (the norm is the absence of a pathological Q wave, the width of the complex is not more than 120 ms). If this interval shifts, then we speak of blockades (full or partial) of the bundle branches or conduction disturbances. Moreover, incomplete blockade of the right bundle branch is an electrocardiographic criterion of right ventricular hypertrophy, and incomplete blockade of the left bundle branch may indicate left ventricular hypertrophy;
They describe the ST segments, which reflect the period of restoration of the initial state of the heart muscle after its complete depolarization (normally located on the isoline) and the T wave, which characterizes the process of repolarization of both ventricles, which is directed upward, asymmetrical, its amplitude is lower than the wave in duration and is longer than the QRS complex.

The decoding work is carried out only by a doctor, however, some ambulance paramedics perfectly recognize common pathologies, which is very important in emergency cases. But first, you still need to know the ECG norm.

This is what the cardiogram of a healthy person looks like, whose heart works rhythmically and correctly, but not everyone knows what this record means, which can change under various physiological conditions, such as pregnancy. In pregnant women, the heart takes a different position in the chest, so the electrical axis shifts. In addition, depending on the duration, the load on the heart is added. An ECG during pregnancy will reflect these changes.

The cardiogram indicators in children are also excellent; they will “grow” with the baby, and therefore will change according to age; only after 12 years, the child’s electrocardiogram begins to approach the ECG of an adult.

The most disappointing diagnosis: heart attack

The most serious diagnosis on the ECG, of course, is, in the recognition of which the cardiogram plays the main role, because it is she (the first!) that finds areas of necrosis, determines the localization and depth of the lesion, and can distinguish an acute infarction from the scars of the past.

The classic signs of myocardial infarction on the ECG are the registration of a deep Q wave (OS), segment elevationST, which deforms R, smoothing it, and the subsequent appearance of a negative pointed isosceles tooth T. This elevation of the ST segment visually resembles a cat’s back (“cat”). However, a distinction is made between myocardial infarction with and without the Q wave.

Video: signs of a heart attack on an ECG

When there's something wrong with your heart

Often in ECG conclusions you can find the expression: “”. As a rule, such a cardiogram is obtained by people whose hearts have had an additional load for a long time, for example, due to obesity. It is clear that the left ventricle has a hard time in such situations. Then the electrical axis deviates to the left, and S becomes greater than R.

hypertrophy of the left (left) and right (right) ventricles of the heart on the ECG

Video: cardiac hypertrophy on ECG

One of the presenters will answer your question.

In questions about interpreting the ECG, be sure to indicate the patient’s gender, age, clinical data, diagnoses and complaints.