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What does the ecg say? Decoding a regular ECG will reveal all the heart’s “secrets”

MINISTRY OF HEALTH OF THE RF

NIZHNY NOVGOROD STATE

MEDICAL INSTITUTE

A.V. SUVOROV

Publishing house NGMI NIZHNY NOVGOROD, 1993

Kyiv – 1999

UDC 616.12–008.3–073.96

Suvorov A.V. Clinical electrocardiography. – Nizhny Novgo-

genus. Publishing house NMI, 1993. 124 p. Ill.

The book by Suvorov A.V. is a good, complete textbook for cardiologists, therapists and senior students of medical institutes on all sections of electrocardiography. The features of ECG recording, normal ECG in standard and unipolar leads, all types of atrioventricular blocks, bundle branch blocks, ECG features in hypertrophies, conduction disorders, arrhythmias, myocardial infarction, ischemic heart disease, thromboembolism, cerebrovascular accidents, etc. are described in detail.

Published by decision of the editorial and publishing council of NMI

Scientific editor Professor S. S. BELOUSOV

Reviewer Professor A. A. OBUKHOVA

ISBN 5-7032-0029-6

PREFACE

Electrocardiography is one of the informative and most common methods of examining patients with heart disease. An ECG also makes it possible to diagnose diseases and syndromes that require emergency cardiac care, and above all myocardial infarction, paroxysmal tachyarrhythmias, conduction disorders with Morgagni–Edams–Stokes syndrome, etc. The need for their diagnosis arises at any time of the day, but, unfortunately, interpretation ECG presents significant difficulties for many doctors, and the reason for this is poor study of the method at the institute, and the lack of courses on ECG diagnostics at advanced training faculties for doctors. It is very difficult to acquire literature on clinical electrocardiography. The author sought to fill this gap.

The manual on electrocardiography is structured traditionally: first, the electrophysiological foundations of electrocardiography are briefly outlined, the section of a normal ECG in standard, unipolar and chest leads, and the electrical position of the heart are presented in detail. The section “ECG for myocardial hypertrophy” describes general signs and criteria for atrial and ventricular hypertrophy.

When describing rhythm and conduction disorders, the pathogenetic mechanisms of the development of syndromes, clinical manifestations and medical tactics are presented.

The sections on ECG diagnosis of coronary artery disease, especially myocardial infarction, as well as infarction-like diseases, which are of great importance for practice, are covered in detail.

For complex ECG syndromes, a diagnostic search algorithm has been developed to facilitate the diagnosis of pathology.

The book is intended for doctors who want to study the theory and practice of this important area of cardiology on their own or with the help of a teacher in a short time.

1. TECHNIQUE FOR REMOVING ELECTROCARDIOGRAM

The electrocardiogram is recorded using electrocardiographs. They can be single-channel or multi-channel. All electrocardiographs (Fig. 1) consist of an input device (1), an amplifier of cardiac biopotentials (2) and a recording device (3).

The input device is a lead switch with cables of different colors extending from it.

The amplifiers have a complex electronic circuit that allows them to enhance the biopotentials of the heart several hundred times. The power source for the amplifier can be batteries or AC power. For safety reasons when working with an electrocardiograph and to prevent interference, the device must be grounded using a wire, one end of which is attached to a special terminal of the electrocardiograph, and the other to a special circuit. If this is not available, in emergency cases, central heating water pipes can be used for grounding (as an exception).

The recording device converts electrical vibrations into mechanical ones. Mechanical pen recording is carried out using ink or carbon paper. Recently, thermal recording has become widespread.

The point is that a feather heated by electric current melts the fusible layer of the tape, exposing the black base.

To record an ECG, the patient is placed on a couch. To obtain good contact, gauze pads moistened with saline are placed under the electrodes. Electrodes are applied to the inner surfaces of the lower third of the upper and lower extremities, a red cable is connected to the right arm, a black cable (patient grounding) to the right leg, a yellow cable to the left arm and a green cable to the left lower extremity. The pear-shaped chest electrode with a suction cup is connected to a white cable and installed in specific positions on the chest.

ECG recording begins with a reference millivolt, which should be equal to 10 mm.

IN 12 leads are recorded without fail - three standard, three unipolar and six chest leads, III, avF leads should preferably be taken in the inhalation phase. Additional leads are recorded according to indications.

IN Each lead should record at least 5 QRS complexes; for arrhythmias, one of the leads (II) is recorded on a long tape. The standard recording speed is 50 mm/sec; for arrhythmias, a speed of 25 mm/sec is used to reduce paper consumption. The voltage of the QRS complexes can be increased and decreased by 2 times depending on the research task.

An application for an ECG study is written on a special form or in a journal, which indicates the full name, gender, blood pressure, age of the patient, and diagnosis. It is imperative to report any medications you are taking.

therapy with cardiac glycosides, β-blockers. diuretics, electrolytes, antiarrhythmic drugs of the quinidine series, rauwolfia, etc.

2. ELECTROPHYSIOLOGICAL BASICS OF ELECTROCARDIOGRAPHY

The heart is a hollow muscular organ divided by a longitudinal septum into two halves: the left arterial and the right venous. The transverse septum divides each half of the heart into two sections: the atrium and the ventricle. The heart performs certain functions: automaticity, excitability, conductivity and contractility.

Automaticity is the ability of the conduction system of the heart to independently produce impulses. To the greatest extent the function

The sinus node (the center of first-order automaticity) has automaticity. At rest, it produces 60–80 impulses per minute. In pathology, the source of rhythm can be the atrioventricular node (the center of second-order automaticity); it produces 40–60 impulses per minute.

The conduction system of the ventricles (idioventricular rhythm) also has an automatic function. However, only 20–50 impulses are generated per minute (third-order center of automaticity).

Excitability is the ability of the heart to respond by contraction to internal and external stimuli. Normally, excitation and contraction of the heart occur under the influence of impulses from the sinus node.

Impulses can be not only nomotopic (from the sinus node), but also heterotopic (from other parts of the conduction system of the heart). If the heart muscle is in a state of excitation, it does not respond to other impulses (absolute or relative refractory phase). Therefore, the heart muscle cannot be in a state of tetanic contraction. When the myocardium is excited, an electromotive force appears in it in the form of vector quantities, which is recorded in the form of an electrocardiogram.

Conductivity. Having originated in the sinus node, the impulse propagates orthograde through the atrial myocardium, then through the atrioventricular node, the His bundle, and the ventricular conduction system. The intraventricular conduction system includes the right branch of the His bundle, the main trunk of the left branch of the His bundle and its two branches, anterior and posterior, and ends with the Purkinje fibers, which transmit impulses to the cells of the contractile myocardium (Fig. 2).

The speed of propagation of the excitation wave in the atria is 1 m/sec, in the ventricular conduction system 4 m/sec, and in the atrioventricular node 0.15 m/sec. Retrograde impulse conduction is sharply slowed down, atrioventricular delay allows the atria to contract before the ventricles. The most vulnerable areas of the conduction system are: atrioventricular node with AV delay, right bundle branch, left anterior branch,

As a result of the impulse, the process of excitation (depolarization) of the myocardium begins at the beginning of the interventricular septum, right and left ventricles. Excitation of the right ventricle may begin earlier (0.02"") than the left. Subsequently, depolarization captures the myocardium of both ventricles, and the electromotive force (total vector) of the left ventricle is greater than the right one.

th. The process of depolarization proceeds from the apex to the base of the heart, from the endocardium to the epicardium.

The process of recovery (repolarization) of the myocardium begins at the epicardium and spreads to the endocardium. During repolarization, a significantly lower electromotive force (EMF) occurs than during depolarization.

The process of depolarization and repolarization of the myocardium is accompanied by bioelectric phenomena. It is known that the protein-lipid membrane of the cell has the properties of a semi-permeable membrane. K+ ions easily penetrate through the membrane and phosphates, sulfates, and proteins do not penetrate. Since these ions are negatively charged,

they attract positively charged K+ ions. The concentration of K+ ions inside the cell is 30 times higher than in the extracellular fluid. Nevertheless, negative charges predominate on the inner surface of the membrane. Na+ ions are located predominantly on the outer surface of the membrane, because the cell membrane at rest is poorly permeable to Na+. The Na+ concentration in the extracellular fluid is 20 times higher than inside the cell. The cell potential at rest is approximately

but 70–90 mV.

When the myocardium is depolarized, the permeability of cell membranes changes, sodium ions easily penetrate the cell and change the charge of the inner surface of the membrane. Due to the fact that Na+ enters the cell, the electrical charge on the outer surface of the membrane changes. Depolarization changes the charge on the outer and inner surfaces of cell membranes. The potential difference that occurs during excitation is called the action potential, it is about 120 mV. During the process of repolarization, K+ ions leave the cell and restore the resting potential. Upon completion of repolarization, Na+ is removed from the cell into the extracellular space using sodium pumps, and K+ ions actively penetrate into the cell through the semi-permeable cell membrane (Fig. 3).

The repolarization process proceeds more slowly than depolarization and causes less emf than the excitation process.

Repolarization begins in the subepicardial layers and ends in the subendocardial layers.

The process of depolarization in a muscle fiber is more complex than in an individual cell. The excited area is charged negatively in relation to the area at rest, and dipole charges are formed, equal in magnitude and opposite in direction. If a dipole with a positive charge moves towards the electrode, a positively directed tooth is formed, if from the electric

troda – negatively directed.

The human heart contains many muscle fibers. Each excited fiber represents a dipole. Dipoles move in different directions. The sum of the vectors of muscle fibers of the right and left ventricles is written as a scalar quantity

– electrocardiograms.

IN In each lead, the ECG curve represents the sum of the vectors of the right and left ventricles and atria (biocardiogram theory).

3. NORMAL ECG IN STANDARD LEADS

IN At the beginning of the 20th century, Einthoven proposed standard leads. Einthoven presented the human body in the form of an equilateral triangle. The first standard lead registers the difference in potentials of the right and left hands, the second – the difference in potentials of the right hand and left leg, the third – the difference in potentials of the left hand and left leg. According to Kirchhoff's law, the second lead represents the algebraic sum of the first and third leads. All elements of the electrocardiogram obey this rule. The first lead reflects the potentials of the subepicardial surface of the left ventricle, the third – the potentials of the posterior wall of the left ventricle and the subepicardial surface of the right ventricle.

A normal ECG in standard leads is represented by a series of waves and intervals, designated by Latin letters (Fig. 4). If the amplitude of the tooth is more than 5 mm, it is indicated by a capital letter, if less than 5 mm, then by a small letter.

Wave P - this atrial complex consists of a hollow ascending limb and a symmetrically located descending limb, which are connected by a rounded apex. The duration (width) of the tooth does not exceed 0.08-0.1 seconds (1 mm - 0.02 ""), the height P is 0.5-2.5 mm. The largest amplitude P in

second standard lead. Normally PII >PI >PIII. PI >0.l"" indicates hypertrophy of the left atrium; with PIII >2.5 mm we can speak of hypertrophy of the right atrium. The duration of the P wave is measured from the beginning of the ascending to the end of the descending knee, the amplitude

P - from the base of the tooth to its top.

Interval PQ (R) – from the beginning of P to the beginning of g or R. It corresponds to the time of passage of the impulse through the atria, through the atrioventricular node, along the His bundle, bundle branches, and Purkinje fibers.

The duration of the PQ interval normally fluctuates 0.12"÷ 0.20"" and depends on the pulse rate. Prolongation of the PQ interval is observed when atrioventricular conduction is impaired; shortening of PQ is associated with a sympatheticoadrenal reaction, premature ventricular excitation syndrome, atrial or nodal pacemaker, etc.

Segment PQ – located from the end of P to the beginning of Q (R). The ratio of P to the PQ segment is called the Makruz index, its norm is 1.1–1.6. An increase in the Macruse index indicates hypertrophy of the left atrium.

The QRS complex reflects the process of ventricular depolarization, measured in the second standard lead from the beginning of Q to the end of S, the normal duration is 0.05–0.1 "". QRS prolongation is associated with myocardial hypertrophy or intraventricular conduction disturbances.

The Q wave is associated with the excitation of the interventricular septum (optional, with a negative amplitude). The duration of Q in the first and second standard leads is up to 0.03"", in the third standard lead - up to 0.04". The amplitude of Q is normally no more than 2 mm or no more than 25% R. Widening of Q and its increase indicate the presence of focal changes in the myocardium.

The R wave is caused by ventricular depolarization, has an ascending limb, an apex, and a descending limb. The time from Q (R) to the perpendicular from the apex of R indicates an increase in the rate of depolarization of the ventricles and is called the time of internal deviation, for the left ventricle no more than 0.04"", for the right - 0.035"". Serration R

Cardiac pathologies today are a fairly common and negative phenomenon. Each of us, feeling unwell, can consult a doctor for a referral for a heart cardiogram and then undergo appropriate treatment.

This painless procedure will allow you to learn about the condition of your heart and its possible pathologies. Early diagnosis of diseases will allow a specialist to prescribe effective treatment that will help you continue to enjoy yourself and lead your usual lifestyle.

Perhaps you have already encountered this diagnostic method, such as a cardiac cardiogram, and were unable to independently decipher the results. Don't worry, we will tell you how to do this and what diseases can be identified.

Cardiogram of the heart - general information

Cardiogram of the heart

A cardiogram is a procedure that records various cardiac pathologies. Anyone who feels unwell can make such a diagnosis, even at home. Almost every ambulance has this device, so a cardiac cardiogram is often performed at home.

This method allows you to identify heart disease at an early stage, and deliver such a patient to the hospital department as soon as possible. If you approach deciphering the indicators of this study in a general way and from the position of a beginner, then it is quite possible to independently understand what the cardiogram shows. The more frequently the teeth are located on the cardiograph tape, the faster the myocardium contracts.

If heartbeats are rare, then zigzags on the cardiogram will be shown much less frequently. In essence, such indicators reflect the nerve impulse of the heart. In order to be able to carry out such a complex medical manipulation as deciphering a cardiac cardiogram, you need to know the meaning of the main indicators. The cardiogram has teeth and intervals, which are designated by Latin letters.

There are only five teeth - these are S, P, T, Q, R, each of these teeth shows the work of a certain department of the heart:

P – normally should be positive, indicating the presence of bioelectricity in the atria;
Q – in the normal state, this wave is negative, characterizing bioelectricity in the interventricular septum;
R – shows the prevalence of biopotential in the ventricular myocardium;
S – normally it is negative, indicating the final process of bioelectricity in the ventricles;
T – during normal heart function it is positive and characterizes the restoration process of biopotential in the heart.

To understand which teeth are considered positive and which are negative, you should know that those teeth that point down are negative, and those that point up are positive. In order to record an electrocardiogram, twelve leads are used: three standard, three unipolar from the limbs and six unipolar from the chest.

It is the ECG that allows you to promptly notice trends in abnormalities in the functioning of the heart muscle and avoid further development of the disease. In fact, a cardiogram is the first thing a heart patient must go through on the path of diagnosis and development of a course of treatment and rehabilitation therapy.

The cost of a cardiac cardiogram is not so high compared to the significant preventive effect that is achieved as a result of its implementation. Performing a cardiogram in private professional clinics costs approximately 500 rubles or more.

The final price of a cardiac cardiogram depends on the pricing policy of the medical institution, the patient’s distance from the cardiologist in case of a doctor’s home call, as well as the completeness of the service provided. The fact is that often, in addition to direct research, doctors offer to develop on the spot an optimal strategy to combat possible deviations.

The ECG examination does not require any preliminary preparation or diet. Usually the procedure is performed from a lying position and takes very little time (up to 10 minutes).

In addition to the standard procedure for recording currents through the chest, there are several methods for conducting electrocardiography. A doctor at our clinic may recommend the following tests:

daily (Holter) ECG monitoring – throughout the day the patient wears a small portable device that records the slightest changes in cardiac activity.

The advantage of the technique is that it is possible to track the functioning of the heart over a long period of time under normal living conditions: this helps to identify pathologies that are not detected during a single electrocardiography;

ECG with stress - during the procedure, physical or medicinal stress can be used, as well as electrical stimulation if the ECG is performed using the transesophageal method.

The procedure is useful in that it helps to establish the exact cause of pain in the heart during physical activity, while at rest no abnormalities are detected.

An ECG is an absolutely safe and painless way to study cardiac activity. To carry it out, the patient must be placed on a couch, special electrodes must be placed in the required places, which will record the impulses. They are generated by the heart muscle during its work.

The tissues of the human body are, to one degree or another, conductors of electric current, so it can be recorded in different parts of the body. The study is carried out in twelve standard leads.

A cardiac cardiogram is not only performed for people with heart problems. This research is also carried out for healthy people. This procedure can determine:

Heart rate.
Regularity of pulse.
The presence of acute or chronic damage to the myocardium.
Metabolism problems.
Causes of chest pain.
The condition of the myocardial walls, their thickness.
Features of the functioning of the embedded pacemaker.

Indicators of a normal cardiogram

Knowing how to decipher the ECG of the heart, it is important to interpret the results of the studies, adhering to a certain sequence. You need to pay attention first to:

Myocardial rhythm.
Electric axis.
Conductivity of intervals.
T wave and ST segments.
Analysis of QRS complexes.

Interpretation of the ECG in order to determine the norm is reduced to data on the position of the teeth. The normal ECG in adults for heart rhythms is determined by the duration of the R-R intervals, i.e. the distance between the tallest teeth. The difference between them should not exceed 10%. A slow rhythm indicates bradycardia, and a rapid rhythm indicates tachycardia. The norm of pulsations is 60-80.

Based on the P-QRS-T intervals located between the teeth, the passage of the impulse through the cardiac sections is judged. As the ECG results will show, the normal interval is 3-5 squares or 120-200 ms. In ECG data, the PQ interval reflects the penetration of biopotential into the ventricles through the ventricular node directly to the atrium.

The QRS complex on the ECG demonstrates ventricular excitation. To determine it, you need to measure the width of the complex between the Q and S waves. A width of 60-100 ms is considered normal. The norm when deciphering an ECG of the heart is considered to be the severity of the Q wave, which should not be deeper than 3 mm and last less than 0.04.

The QT interval indicates the duration of ventricular contraction. The norm here is 390-450 ms, a longer interval indicates ischemia, myocarditis, atherosclerosis or rheumatism, and a shorter interval indicates hypercalcemia.

When deciphering the ECG norm, the electrical axis of the myocardium will show areas of impulse conduction disturbance, the results of which are calculated automatically. To do this, the height of the teeth is monitored:

The S wave should normally not exceed the R wave.
If there is a deviation to the right in the first lead, when the S wave is below the R wave, this indicates that there are deviations in the functioning of the right ventricle.
A reverse deviation to the left (the S wave exceeds the R wave) indicates left ventricular hypertrophy.

The QRS complex will tell you about the passage of biopotential through the myocardium and septum. A normal ECG of the heart will be in the case when the Q wave is either absent or does not exceed 20-40 ms in width and a third of the R wave in depth.

The ST segment should be measured between the end of the S wave and the beginning of the T wave. Its duration is affected by the pulse rate. Based on the ECG results, the normal segment occurs in the following cases: ST depression on the ECG with permissible deviations from the isoline of 0.5 mm and elevation in leads of no more than 1 mm.

Indications for an electrocardiogram for adults:

It is definitely worth doing a cardiogram of the heart if you suspect a disease of the “motor” or organs of the cardiovascular system and the first alarming symptoms appear: shortness of breath, pressing and squeezing pain in the chest, heaviness, tachycardia, edema, and others;
a cardiogram can help prevent serious pathologies for those who are at risk of heart disorders (smokers, overweight people, hypertensive people, with a hereditary predisposition, as well as an annual examination for people over 40 years of age);
upon the accomplished fact of detection of heart disease - behind the dynamics of the development of pathology and control over the situation.

ECG indications for children:

A cardiogram of the child’s heart is performed for preventive examination in all children under 1 year of age;
if there is a suspicion of congenital heart disease. Which can be judged by early symptoms;
with possible acquired pathologies of the heart, as well as the involvement of the organ in the symptoms of disturbances in the functioning of other body systems.

An ECG examination is the first part of the diagnosis. The qualifications of the physician who interprets the research results are of paramount importance. The developed treatment strategy, and therefore a successful outcome for the patient, depends on the correct interpretation of the image of heart sounds.

To provide emergency care, private clinics provide the service of a cardiologist visiting the patient directly at home, as well as conducting EGC at home. In this case, you should only contact reliable clinics with a reliable reputation.

It also remains to remember that an ECG is an effective, but far from the only means of diagnosing cardiac pathologies. For a more accurate diagnosis, a stress ECG, echocardiography, pulse oximetry, a number of laboratory tests and other studies may be prescribed.

One of the main advantages of ECG is that the traditional procedure has no contraindications. Its implementation may be somewhat complicated if you have chest injuries, a high degree of hair growth, or severe obesity.

Data may also be distorted if you have a pacemaker. A stress ECG is not performed in some cases:

in the acute period of myocardial infarction,
for acute infections,
aortic aneurysm dissection,
worsening of heart failure, ischemia and hypertension,
in the stage of decompensation of diseases of other body systems.

Before performing a cardiogram, the doctor will tell the patient about all the aspects of preparing for the study. What can cause incorrect readings on an ECG:

consumption of any alcohol-containing drinks, as well as energy cocktails;
smoking 3-4 hours before the procedure;
excessive consumption of food 3-4 hours before the test. It is better to do a cardiogram on an empty stomach;
strong physical activity the day before;
emotional stress;
use of medications that affect heart activity;
coffee drunk 2-3 hours before the ECG.

Many people forget that deciphering a cardiogram can erroneously show the presence of pathologies, due to the experiences experienced by a person the day before or if the patient was late for the ECG and ran to the office.

Before performing an ECG, you need to sit quietly in the corridor, relaxing and not thinking about anything, for about 10-15 minutes. Carrying out a cardiogram will not take much time. A person entering the office must undress to the waist and lie down on the couch.

Sometimes the doctor asks you to remove all clothes down to your underwear before the examination, which is due to the diagnosis that is suspected in the patient. Next, the doctor applies a special product in the form of a gel to certain places on the body, which serve as attachment points for wires coming from the cardiograph.

Using special electrodes located on the desired areas, the device detects even the slightest heart impulses, which are reflected on the cardiograph tape in the form of a straight line. The duration of the procedure varies in the range of several minutes.

ECG technique

As planned, ECG recording is carried out in a specialized room equipped with an electrocardiograph. Some modern cardiographs use a thermal printing mechanism instead of a conventional ink recorder, which uses heat to burn the cardiogram curve onto the paper.

But in this case, the cardiogram requires special paper or thermal paper. For clarity and convenience of calculating ECG parameters, cardiographs use graph paper. In the latest modifications of cardiographs, the ECG is displayed on the monitor screen, decrypted using the supplied software, and not only printed on paper, but also saved on digital media (disk, flash drive).

Despite all these improvements, the principle of the ECG recording cardiograph has remained virtually unchanged since Einthoven developed it. Most modern electrocardiographs are multichannel. Unlike traditional single-channel devices, they record not one, but several leads at once.

In 3-channel devices, first standard I, II, III are recorded, then enhanced unipolar leads from the limbs aVL, aVR, aVF, and then the chest leads - V1-3 and V4-6. In 6-channel electrocardiographs, standard and unipolar limb leads are first recorded, and then all chest leads.

The room in which recording is carried out must be removed from sources of electromagnetic fields and X-ray radiation. Therefore, the ECG room should not be placed in close proximity to the X-ray room, rooms where physiotherapeutic procedures are carried out, as well as electric motors, power panels, cables, etc.

There is no special preparation before recording an ECG. It is advisable for the patient to be rested and well-slept. Previous physical and psycho-emotional stress can affect the results and is therefore undesirable. Sometimes food intake can also affect the results. Therefore, an ECG is recorded on an empty stomach, no earlier than 2 hours after a meal.

While recording an ECG, the subject lies on a flat, hard surface (on a couch) in a relaxed state. Places for applying electrodes must be free of clothing. Therefore, you need to undress to the waist, free your shins and feet from clothes and shoes.

Electrodes are applied to the inner surfaces of the lower thirds of the legs and feet (the inner surface of the wrist and ankle joints). These electrodes have the form of plates and are designed for recording standard leads and unipolar leads from the limbs. These same electrodes may look like bracelets or clothespins.

In this case, each limb has its own electrode. To avoid errors and confusion, the electrodes or wires through which they are connected to the device are color coded:

To the right hand - red;
To the left hand - yellow;
To the left leg - green;
To the right leg - black.

Why do you need a black electrode? After all, the right leg is not included in the Einthoven triangle, and readings are not taken from it. The black electrode is for grounding. According to basic safety requirements, all electrical equipment, incl. and electrocardiographs must be grounded. For this purpose, ECG rooms are equipped with a grounding circuit.

And if the ECG is recorded in a non-specialized room, for example, at home by ambulance workers, the device is grounded to a central heating radiator or to a water pipe. For this there is a special wire with a fixing clip at the end.

Electrodes for recording chest leads have the shape of a suction cup and are equipped with a white wire. If the device is single-channel, there is only one suction cup, and it is moved to the required points on the chest.

In multi-channel devices there are six of these suction cups, and they are also marked with color:

V1 – red;
V2 – yellow;
V3 – green;
V4 – brown;
V5 – black;
V6 – purple or blue.

It is important that all electrodes adhere tightly to the skin. The skin itself should be clean, free of oil, fat and sweat. Otherwise, the quality of the electrocardiogram may deteriorate. Inductive currents, or simply interference, arise between the skin and the electrode.

Quite often, the tip occurs in men with thick hair on the chest and limbs. Therefore, here you need to be especially careful to ensure that the contact between the skin and the electrode is not broken. The interference sharply worsens the quality of the electrocardiogram, which displays small teeth instead of a straight line.

Therefore, it is recommended to degrease the area where the electrodes are applied with alcohol and moisten it with a soap solution or conductive gel. For electrodes from the limbs, gauze wipes soaked in saline solution are also suitable. However, it should be borne in mind that the saline solution dries quickly and the contact may be broken.

Before recording, it is necessary to check the calibration of the device. For this purpose, it has a special button - the so-called. reference millivolt. This value reflects the height of the tooth at a potential difference of 1 millivolt (1 mV). In electrocardiography, the reference millivolt value is 1 cm. This means that with a difference in electrical potentials of 1 mV, the height (or depth) of the ECG wave is 1 cm.

Electrocardiograms are recorded at a tape speed of 10 to 100 mm/s. True, extreme values are used very rarely. Basically, the cardiogram is recorded at a speed of 25 or 50 mm/s. Moreover, the last value, 50 mm/s, is standard and most often used.

A speed of 25 mm/h is used where the greatest number of heart contractions needs to be recorded. After all, the lower the speed of the tape, the greater the number of heart contractions it displays per unit of time. An ECG is recorded during quiet breathing.

In this case, the subject should not talk, sneeze, cough, laugh, or make sudden movements. When registering standard lead III, a deep breath with a short breath hold may be required. This is done in order to distinguish functional changes, which are often found in this lead, from pathological ones.

The section of the cardiogram with teeth corresponding to the systole and diastole of the heart is called the cardiac cycle. Typically, 4-5 cardiac cycles are recorded in each lead. In most cases this is enough. However, in case of cardiac arrhythmias or suspected myocardial infarction, recording up to 8-10 cycles may be required. To switch from one lead to another, the nurse uses a special switch.

At the end of the recording, the subject is released from the electrodes, and the tape is signed - their full name is indicated at the very beginning. and age. Sometimes, to detail the pathology or determine physical endurance, an ECG is performed against the background of medication or physical activity.

Drug tests are carried out with various drugs - atropine, chimes, potassium chloride, beta-blockers. Physical activity is carried out on an exercise bike (bicycle ergometry), walking on a treadmill, or walking for certain distances. To ensure completeness of information, an ECG is recorded before and after exercise, as well as directly during bicycle ergometry.

Many negative changes in heart function, such as rhythm disturbances, are transient and may not be detected during ECG recording even with a large number of leads. In these cases, Holter monitoring is performed - a Holter ECG is recorded in continuous mode throughout the day.

A portable recorder equipped with electrodes is attached to the patient's body. Then the patient goes home, where he follows his usual routine. After 24 hours, the recording device is removed and the available data is decrypted.

A normal ECG looks something like this:

All deviations in the cardiogram from the midline (isoline) are called waves.

Teeth deviated upward from the isoline are considered to be positive, and downward - negative. The space between the teeth is called a segment, and the tooth and its corresponding segment are called an interval.

Before finding out what a particular wave, segment or interval represents, it is worth briefly dwelling on the principle of forming an ECG curve.

Normally, the cardiac impulse originates in the sinoatrial (sinus) node of the right atrium.

Then it spreads to the atria - first the right, then the left. After this, the impulse is sent to the atrioventricular node (atrioventricular or AV junction), and then along the His bundle.

The branches of the His bundle or pedicles (right, left anterior and left posterior) end in Purkinje fibers. From these fibers, the impulse propagates directly to the myocardium, leading to its contraction - systole, which is replaced by relaxation - diastole.

The passage of an impulse along a nerve fiber and the subsequent contraction of the cardiomyocyte is a complex electromechanical process, during which the values of the electrical potentials on both sides of the fiber membrane change. The difference between these potentials is called the transmembrane potential (TMP).

This difference is due to the different permeability of the membrane to potassium and sodium ions. There is more potassium inside the cell, sodium - outside it. As the pulse passes, this permeability changes. In the same way, the ratio of intracellular potassium and sodium and TMP changes.

When an excitatory impulse passes, TMP increases inside the cell.

In this case, the isoline shifts upward, forming the ascending part of the tooth. This process is called depolarization. Then, after the passage of the pulse, the TMP tries to take the original value.

However, the permeability of the membrane to sodium and potassium does not immediately return to normal and takes some time.

This process, called repolarization, is manifested on the ECG by a downward deviation of the isoline and the formation of a negative wave. Then the polarization of the membrane takes on the initial resting value (TMP), and the ECG again takes on the character of an isoline. This corresponds to the diastole phase of the heart.

It is noteworthy that the same tooth can look both positive and negative. It all depends on the projection, i.e. the lead in which it is recorded.

ECG waves are usually designated in Latin capital letters, starting with the letter P. The parameters of the waves are direction (positive, negative, biphasic), as well as height and width. Since the height of the tooth corresponds to the change in potential, it is measured in mV.

As already mentioned, a height of 1 cm on the tape corresponds to a potential deviation of 1 mV (reference millivolt). The width of a tooth, segment or interval corresponds to the duration of a phase of a particular cycle. This is a temporary value, and it is customary to denote it not in millimeters, but in milliseconds (ms).

When the tape moves at a speed of 50 mm/s, each millimeter on paper corresponds to 0.02 s, 5 mm - 0.1 ms, and 1 cm - 0.2 ms. It's very simple: if 1 cm or 10 mm (distance) is divided by 50 mm/s (speed), we get 0.2 ms (time).

Wave R. Displays the spread of excitation through the atria.

In most leads it is positive, and its height is 0.25 mV and width is 0.1 ms. Moreover, the initial part of the wave corresponds to the passage of the impulse through the right ventricle (since it is excited earlier), and the final part - along the left.

The P wave may be negative or biphasic in leads III, aVL, V1, and V2.

P-Q interval (or P-R) is the distance from the beginning of the P wave to the beginning of the next wave - Q or R.

This interval corresponds to the depolarization of the atria and the passage of the impulse through the AV junction, and further along the His bundle and its branches. The size of the interval depends on the heart rate (HR) - the higher it is, the shorter the interval.

Normal values are in the range of 0.12 – 0.2 ms. A wide interval indicates a slowdown in atrioventricular conduction.

QRS complex. If P represents the functioning of the atria, then the following waves, Q, R, S and T, reflect the function of the ventricles, and correspond to the various phases of depolarization and repolarization.

The set of QRS waves is called the ventricular QRS complex. Normally, its width should be no more than 0.1 ms. An excess indicates a violation of intraventricular conduction.

Wave Q. Corresponds to depolarization of the interventricular septum.

This tooth is always negative. Normally, the width of this wave does not exceed 0.3 ms, and its height is no more than ¼ of the next R wave in the same lead. The only exception is lead aVR, where a deep Q wave is recorded.

In other leads, a deep and widened Q wave (in medical slang - kuishche) may indicate a serious heart pathology - acute myocardial infarction or scars after a heart attack.

Although other reasons are possible - deviations of the electrical axis due to hypertrophy of the heart chambers, positional changes, blockade of the bundle branches.

Wave R. Displays the spread of excitation throughout the myocardium of both ventricles.

This wave is positive, and its height does not exceed 20 mm in the limb leads, and 25 mm in the chest leads. The height of the R wave is not the same in different leads.

Normally, it is greatest in lead II. In ore leads V1 and V2 it is low (for this reason it is often denoted by the letter r), then it increases in V3 and V4, and in V5 and V6 it decreases again. In the absence of the R wave, the complex takes on the appearance of QS, which may indicate transmural or cicatricial myocardial infarction.

Wave S. Displays the passage of the impulse along the lower (basal) part of the ventricles and the interventricular septum.

This is a negative tooth and its depth varies widely, but should not exceed 25 mm. In some leads the S wave may be absent.

Wave T. The final section of the ECG complex, reflecting the phase of rapid ventricular repolarization.

In most leads this wave is positive, but it can also be negative in V1, V2, aVF. The height of the positive waves directly depends on the height of the R wave in the same lead - the higher the R, the higher the T.

The causes of a negative T wave are varied - small-focal myocardial infarction, dyshormonal disorders, previous food intake, changes in the electrolyte composition of the blood, and much more. The width of the T waves usually does not exceed 0.25 ms.

S-T segment is the distance from the end of the ventricular QRS complex to the beginning of the T wave, corresponding to full coverage of the ventricles by excitation.

Normally, this segment is located on the isoline or deviates from it slightly - no more than 1-2 mm. Large S-T deviations indicate a severe pathology - a violation of the blood supply (ischemia) of the myocardium, which can lead to a heart attack.

Other, less serious reasons are also possible - early diastolic depolarization, a purely functional and reversible disorder mainly in young men under 40 years of age.

Q-T interval is the distance from the beginning of the Q wave to the T wave.

Corresponds to ventricular systole. The size of the interval depends on the heart rate - the faster the heart beats, the shorter the interval.

U wave. An unstable positive wave, which is recorded after the T wave after 0.02-0.04 s. The origin of this tooth is not fully understood, and it has no diagnostic value.

From a physical point of view, the work of the heart is an automatic transition from the depolarization phase to the repolarization phase of the heart muscle. In other words, there is a constant change in states of contraction and relaxation of muscle tissue, in which, accordingly, the excitation of myocardial cells is replaced by their restoration.

The design of the ECG device allows you to record electrical impulses that occur in these phases and record them graphically. This is precisely what explains the unevenness of the curve in the cardiogram figure.

To learn how to interpret ECG diagrams, you need to know what elements they consist of, namely:

tooth – a convex or concave part of a curve relative to the horizontal axis;
segment - a straight line segment between two adjacent teeth;
interval – a combination of a tooth and a segment.

Recording of cardiac data is carried out over several cycles, since not only the characteristics of each element of the electrocardiogram are of medical importance, but also their comparability within several cycles.

It is immediately worth noting that with the help of an electrocardiogram you can find out how the heart works. Many people wonder how to decipher a heart cardiogram. The decoding is carried out by the doctor by taking measurements of the duration of the intervals between the components.

This calculation makes it possible to estimate the rhythm frequency, and the teeth show the nature of the heart rhythm. This whole procedure is carried out in a certain order, where violations and norms are determined:

first of all, heart rate and rhythm indicators are recorded; with a normal electrocardiogram, the rhythm will be sinus, and the heart rate will be from sixty to eighty beats per minute;
then they begin to calculate the intervals; normally, the QT interval will be 390-450 ms. If there is a prolongation of this interval, then the doctor may suspect coronary heart disease, rheumatism or myocarditis. And if, on the contrary, its shortening is noted, then hypercalcemia can be suspected;
then the EOS is calculated based on the height of the waves from the midline (in a normal ECG the R wave will be higher than the S wave);
the QRS complex is studied, normally its width is no more than one hundred and twenty ms;
Lastly, the ST segments are described, normally it should be in the midline. This segment shows the recovery period after depolarization of the heart muscle.

Thus, deciphering the cardiogram of the heart, the normal photo will look like this: the Q and S waves will always be negative, P and T, R will be positive. The heart rate will vary from sixty to eighty beats per minute, and the rhythm is always sinus. The R wave will be higher than the S wave, and the QRS complex will not be more than one hundred and twenty ms wide.

Decoding a cardiogram is a long process that depends on many indicators. Before deciphering the cardiogram, it is necessary to understand all the deviations in the functioning of the heart muscle. Atrial fibrillation is characterized by irregular contractions of the muscle, which can be completely different.

This violation is dictated by the fact that the clock is set not by the sinus node, as it should happen in a healthy person, but by other cells. The heart rate in this case ranges from 350 to 700. In this condition, the ventricles are not fully filled with incoming blood, which causes oxygen starvation, which affects all organs in the human body.

An analogue of this condition is atrial fibrillation. The pulse in this state will be either below normal (less than 60 beats per minute), or close to normal (60 to 90 beats per minute), or above the specified norm. On the electrocardiogram you can see frequent and constant contractions of the atria and, less often, the ventricles (usually 200 per minute).

This is atrial flutter, which often occurs already in the acute phase. But at the same time, the patient tolerates it more easily than flickering. Blood circulation defects in this case are less pronounced. Trembling can develop as a result of surgery, various diseases such as heart failure or cardiomyopathy.

When a person is examined, fluttering can be detected due to rapid rhythmic heartbeats and pulse, swollen veins in the neck, increased sweating, general impotence and shortness of breath. Conduction disorder - this type of heart disorder is called blockade.

The occurrence is often associated with functional disorders, but it can also be the result of various types of intoxication (due to alcohol or taking medications), as well as various diseases. There are several types of disorders that a heart cardiogram shows. Deciphering these violations is possible based on the results of the procedure.

Sinus arrhythmia can be physiological or pathological. In the physiological form, respiratory arrhythmia is observed, and in the pathological form, a non-respiratory form is observed. The physiological form most often occurs in young people who play sports and suffer from neuroses and neurocirculatory dystonia.

With sinus arrhythmia, it will have the following picture: preserved sinus rhythm, the arrhythmia disappears during breath holding, fluctuations in R-R intervals are observed. Pathological sinus arrhythmia usually appears in elderly people when falling asleep or waking up, as well as in patients with coronary heart disease and cardiomyopathy.

With this form, the cardiogram will show signs of preserved sinus rhythm, which is noted even during breath-holding and abrupt changes in the duration of the R-R intervals.

How does myocardial infarction manifest itself on a cardiogram?

Myocardial infarction is an acute condition of coronary artery disease in which there is insufficient blood supply to some part of the heart muscle. If this area is starved for more than fifteen to twenty minutes, its necrosis occurs, that is, necrosis.

This condition leads to disruption of the entire cardiovascular system and is very dangerous and life-threatening. If there are characteristic symptoms of cardiac dysfunction, the patient is prescribed an electrocardiogram.

Decoding the cardiogram of the heart during a heart attack will have pronounced changes on paper. The following ECG signs indicate a heart attack:

significant increase in heart rate;
ST segment elevation is noted;
The ST segment will have fairly persistent depression in the leads;
increase in the duration of the QRS complex;
The cardiogram shows signs of a previous heart attack.

In such a serious disease as myocardial infarction, it is the electrocardiogram that can be the first to recognize dead zones on the heart muscle, determine the location of the lesion and its depth. With the help of this study, the doctor can easily distinguish an acute infarction from an enlargement.

Due to the elevation of the ST segment, deformation of the R wave will be noted, it becomes smoothed. Then a negative T will appear. This total rise in ST on the cardiogram will resemble the arched back of a cat. Sometimes during a heart attack, a Q wave may be observed on the cardiogram.

An electrocardiogram should only be performed by a specialist in a medical facility or by an emergency physician at the patient’s home. Today you can do an ECG at home by calling an ambulance. Almost every ambulance has a special device - an electrocardiograph.

It is small and very convenient, therefore, in case of certain complaints, the patient can undergo this manipulation without visiting a medical institution.

A patient's ECG data can sometimes be different, so if you know how to read a cardiac ECG but see different results in the same patient, don't make a diagnosis prematurely. Accurate results will require taking into account various factors:

Often distortions are caused by technical defects, for example, inaccurate gluing of the cardiogram.
Confusion can be caused by Roman numerals, which are the same in the normal and inverted directions.
Sometimes problems arise as a result of cutting the diagram and losing the first P wave or the last T wave.
Preliminary preparation for the procedure is also important.
Electrical appliances operating nearby affect the alternating current in the network, and this is reflected in the repetition of the teeth.
The instability of the zero line may be affected by the patient’s uncomfortable position or anxiety during the session.
Sometimes the electrodes become dislodged or incorrectly positioned.

Therefore, the most accurate measurements are obtained using a multichannel electrocardiograph. It is with them that you can test your knowledge of how to decipher an ECG yourself, without fear of making a mistake in making a diagnosis (treatment, of course, can only be prescribed by a doctor).

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

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

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

Prolongation of the QT interval indicates the development of coronary heart disease, rheumatic disease, and sclerotic disorders. A shortening of the interval indicates hypercalcemia.
An altered Q wave is a signal of myocardial dysfunction.
Sharpening and increased height of the R wave indicates right ventricular hypertrophy.
A split and widened P wave indicates left atrial hypertrophy.
An increase in the PQ interval and disruption of impulse conduction occurs with atrioventricular block.
The degree of deviation from the isoline in the R-ST segment diagnoses myocardial ischemia.
Elevation of the ST segment above the isoline is a threat of acute infarction; a decrease in the segment registers ischemia.

There is another method for reading a heart cardiogram yourself. For this you need an electrocardiographic ruler. It helps to decipher an ECG at a speed of 25 mm/s or 50 mm/s. The cardiac ruler consists of divisions (scales) defining:

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

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

Thanks to the ECG, it is possible to diagnose many abnormalities in cardiac activity. The main ones are:

Hypertrophy of departments.

This problem occurs due to hemodynamic disturbances. Deviations in the movement of blood through the vessels cause overload of the organ chambers, causing the atria or ventricles to increase in size.

This problem can be identified by the following signs:

Changes in the electrical axis of the heart.
Increasing the excitation vector.
Increase in R wave amplitude.
Changing the position of the transition zone.

Angina pectoris.

When there are no attacks of the disease, there may be no signs of it on the ECG. This disease exhibits the following features:

The location of the S-T segment is below the isoline.
Changes in T wave mapping.

Arrhythmia.

In the presence of this pathology, disturbances in the formation of the impulse occur. Because of this, disruptions in the pulse rhythm occur.
It appears on the ECG as follows:

There are fluctuations in the P-Q and Q-T display.
Deviations from the norm in the interval between R-waves.

Tachycardia.

This is a type of arrhythmia in which the heart rate increases. Its signs on the cardiogram:

The gap between the R-teeth is less than normal.
The P-Q section decreases.
The direction of the teeth remains within normal limits.

Bradycardia.

This is another type of arrhythmia in which the heart rate decreases. Signs:

The gap between R and R is increased.
Growth of the Q-T region is observed.
The direction of the teeth changes slightly.

Aneurysm.

In this case, the myocardium increases due to changes in the muscle layers or pathologies in the development of the organ during the prenatal period.

Extrasystole.

During extrasystole, a focus is formed in the heart that is capable of creating an electrical impulse, which disrupts the rhythm of the sinus node.

Pericarditis.

This disease is characterized by inflammation of the layers of the pericardial sac.

Other diseases that can be detected using a cardiogram include ischemic heart disease, myocardial infarction, myocarditis, heart failure, etc.

This disease is characterized by inflammation of the layers of the pericardial sac. Other diseases that can be detected using a cardiogram include ischemic heart disease, myocardial infarction, myocarditis, heart failure, etc.

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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Heartbeat

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 monitoring;
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 further 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 decoding 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 the manifestation 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 (the average is 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 of varying lengths between contractions. 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: coronary 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 apparatus 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 capable of detecting 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 an 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:

Electrocardiography is a method for diagnosing the condition of the myocardium. This article will discuss ECG norms in children, adults and women during pregnancy. In addition, the reader will learn about what cardiography is, how an ECG is done, and what the interpretation of a cardiogram is.

Questions that arise while reading the article can be asked to specialists using the online form.

Free consultations are available 24 hours a day.

Electrocardiography is a method used to record electrical currents that occur during contractions and relaxations of the heart muscle. An electrocardiograph is used to conduct the study. Using this device, it is possible to record electrical impulses that come from the heart and convert them into a graphic drawing. This image is called an electrocardiogram.

Electrocardiography reveals disturbances in the functioning of the heart and disruptions in the functioning of the myocardium. In addition, after decoding the results of the electrocardiogram, some non-cardiac diseases can be detected.

How does an electrocardiograph work?

The electrocardiograph consists of a galvanometer, amplifiers and a recorder. Weak electrical impulses that arise in the heart are read by electrodes and then amplified. The galvanometer then receives data on the nature of the pulses and transmits them to the recorder. In the recorder, graphic images are printed on special paper. The graphs are called cardiograms.

How is an ECG done?

Electrocardiography is performed according to established rules. Below is the procedure for taking an ECG:

The person removes metal jewelry, removes clothing from the legs and upper body, and then assumes a horizontal position.
The doctor treats the contact points between the electrodes and the skin, and then places the electrodes in certain places on the body. Next, he fixes the electrodes on the body with clips, suction cups and bracelets.
The doctor attaches the electrodes to the cardiograph, after which the impulses are recorded.
A cardiogram is recorded, which is the result of electrocardiography.

Separately, it should be said about the leads used for ECG. The following leads are used:

3 standard leads: one of them is located between the right and left arms, the second – between the left leg and right arm, the third – between the left leg and left arm.
3 limb leads with enhanced character.
6 leads located on the chest.

In addition, additional leads can be used if necessary.

After the cardiogram is recorded, it is necessary to decipher it. This will be discussed further.

Decoding the cardiogram

Conclusions about diseases are made on the basis of heart parameters obtained after deciphering the cardiogram. Below is the procedure for deciphering the ECG:

The heart rhythm and myocardial conductivity are analyzed. To do this, the regularity of contractions of the heart muscle and the frequency of myocardial contractions are assessed, and the source of excitation is determined.
The regularity of heart contractions is determined as follows: the R-R intervals between successive cardiac cycles are measured. If the measured R-R intervals are the same, then a conclusion is made about the regularity of contractions of the heart muscle. If the duration of the R-R intervals is different, then a conclusion is drawn about the irregularity of heart contractions. If a person exhibits irregular contractions of the myocardium, then a conclusion is drawn about the presence of arrhythmia.
Heart rate is determined by a certain formula. If a person’s heart rate exceeds the norm, then a conclusion is drawn about the presence of tachycardia, but if a person’s heart rate is below normal, then a conclusion is drawn about the presence of bradycardia.
The point from which the excitation comes is determined as follows: the movement of contraction in the cavities of the atria is assessed and the relationship of the R waves to the ventricles is established (according to the QRS complex). The nature of the heart rhythm depends on the source that causes the excitation.

The following heart rhythm patterns are observed:

The sinusoidal nature of the heart rhythm, in which the P waves in the second lead are positive and are located in front of the ventricular QRS complex, and the P waves in the same lead have an indistinguishable shape.
Atrial rhythm of the heart, in which the P waves in the second and third leads are negative and are located in front of the unchanged QRS complexes.
The ventricular nature of the heart rhythm, in which there is deformation of the QRS complexes and loss of connection between the QRS (complex) and the P waves.

Cardiac conductivity is determined as follows:

Measurements of P wave length, PQ interval length, and QRS complex are assessed. Exceeding the normal duration of the PQ interval indicates that the conduction velocity in the corresponding cardiac conduction section is too low.
The rotations of the myocardium around the longitudinal, transverse, anterior and posterior axes are analyzed. To do this, the position of the electrical axis of the heart in the general plane is assessed, after which the presence of rotations of the heart along one or another axis is determined.
The atrial P wave is analyzed. To do this, the amplitude of the P wave is assessed and the duration of the P wave is measured. Afterwards, the shape and polarity of the P wave are determined.
The ventricular complex is analyzed. For this purpose, the QRS complex, RS-T segment, QT interval, T wave are assessed.

When assessing the QRS complex, the following is done: the characteristics of the Q, S and R waves are determined, the amplitude values of the Q, S and R waves in a similar lead and the amplitude values of the R/R waves in different leads are compared.

At the time of evaluation of the RS-T segment, the nature of the displacement of the RS-T segment is determined. The displacement can be horizontal, oblique and oblique.

During the period of analysis of the T wave, the nature of the polarity, amplitude and shape are determined. The QT interval is measured by the time from the beginning of the QRT complex to the end of the T wave. When assessing the QT interval, do the following: analyze the interval from the starting point of the QRS complex to the end point of the T wave. To calculate the QT interval, use the Bezzet formula: the QT interval is equal to the product of the R-R interval and a constant coefficient.

The coefficient for QT depends on gender. For men, the constant coefficient is 0.37, and for women – 0.4.

A conclusion is made and the results are summed up.

At the end of the ECG, the specialist draws conclusions about the frequency of contractile function of the myocardium and cardiac muscle, as well as the source of excitation and the nature of the heart rhythm and other indicators. In addition, an example is given of the description and characteristics of the P wave, QRS complex, RS-T segment, QT interval, T wave.

Based on the conclusion, a conclusion is made that the person has heart disease or other ailments of the internal organs.

Electrocardiogram norms

The table with ECG results has a visual appearance, consisting of rows and columns. In the 1st column, the rows list: heart rate, examples of contraction frequency, QT intervals, examples of axis displacement characteristics, P wave indicators, PQ indicators, examples of QRS indicator. ECG is performed in the same way in adults, children and pregnant women, but the norm is different.

The ECG norm for adults is presented below:

heart rate in a healthy adult: sinus;
P wave index in a healthy adult: 0.1;
heart rate in a healthy adult: 60 beats per minute;
QRS indicator in a healthy adult: from 0.06 to 0.1;
QT score in a healthy adult: 0.4 or less;
RR in a healthy adult: 0.6.

If deviations from the norm are observed in an adult, a conclusion is drawn about the presence of a disease.

The norms of cardiogram indicators in children are presented below:

P wave index in a healthy child: 0.1 or less;
heart rate in a healthy child: 110 or less beats per minute in children under 3 years of age, 100 or less beats per minute in children under 5 years of age, no more than 90 beats per minute in adolescent children;
QRS indicator in all children: from 0.06 to 0.1;
QT score in all children: 0.4 or less;
the PQ indicator for all children: if the child is under 14 years old, then an example of the PQ indicator is 0.16, if the child is from 14 to 17 years old, then the PQ indicator is 0.18, after 17 years the normal PQ indicator is 0.2.

If any deviations from the norm are detected in children when interpreting the ECG, then treatment should not be started immediately. Some heart problems improve with age in children.

But in children, heart disease can also be congenital. It is possible to determine whether a newborn child will have a heart pathology at the stage of fetal development. For this purpose, electrocardiography is performed on women during pregnancy.

The normal electrocardiogram indicators in women during pregnancy are presented below:

heart rate in a healthy adult child: sinus;
P wave index in all healthy women during pregnancy: 0.1 or less;
heart muscle contraction frequency in all healthy women during pregnancy: 110 or less beats per minute in children under 3 years of age, 100 or less beats per minute in children under 5 years of age, no more than 90 beats per minute in adolescent children;
QRS indicator for all expectant mothers during pregnancy: from 0.06 to 0.1;
QT index in all expectant mothers during pregnancy: 0.4 or less;
PQ indicator for all expectant mothers during pregnancy: 0.2.

It is worth noting that during different periods of pregnancy, ECG readings may differ slightly. In addition, it should be noted that performing an ECG during pregnancy is safe for both the woman and the developing fetus.

Additionally

It is worth saying that under certain circumstances, electrocardiography can give an inaccurate picture of a person’s health status.

If, for example, a person subjected himself to heavy physical activity before an ECG, then when deciphering the cardiogram, an erroneous picture may be revealed.

This is explained by the fact that during physical activity the heart begins to work differently than at rest. During physical activity, the heart rate increases, and some changes in the rhythm of the myocardium may be observed, which is not observed at rest.

It is worth noting that the work of the myocardium is affected not only by physical stress, but also by emotional stress. Emotional stress, like physical stress, disrupts the normal course of myocardial function.

At rest, the heart rhythm normalizes and the heartbeat evens out, so before electrocardiography you must be at rest for at least 15 minutes.