Home Orthopedics Heart rhythm disturbances ecg. Atrial fibrillation on the ECG: description and signs

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Heart rhythm disturbances ecg. Atrial fibrillation on the ECG: description and signs

Heart rhythm disturbances have recently become a fairly common pathology, and the quality of medical care depends on timely diagnosis. An idea of what atrial fibrillation looks like on an ECG will help identify this disease.

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The mechanism of occurrence of this disease

Failure of the contractile function of the heart muscle is usually caused by impaired excitability and conduction. In clinical practice, this includes atrial flutter and fibrillation, ventricular fibrillation or fibrillation. If a patient has chronic cardiac pathology, specialists are more often faced with atrial fibrillation.

It should be noted that atrial fibrillation is one of the most common and severe diseases of the cardiovascular system. This pathology was first diagnosed back in the 19th century, but the disease received its modern name at the beginning of the 20th century in the works of domestic scientists.

The main component of the development of the disease is considered to be a disturbance in the conduction of electrical and nerve impulses in the fibers of the atria. In this case, damage to the ventricles of the heart is secondary.

The entire nervous system of the heart is autonomous and depends little on the human central nervous system. The work of the heart muscle is regulated by several nodes. It is the malfunction and weakening of the conduction function in the sinus-atrial node that causes an increase in atrial excitability. The above node ceases to fulfill its main role as a pacemaker, which can be perfectly confirmed by various ECG signs of atrial fibrillation.

A large number of ectopic foci occur in the atria, which leads to a disruption in the rhythm of contractions of this part of the heart. Due to the fact that the myocardium is unable to respond to all incoming impulses, contractile movements occur in individual fibers of the atrial muscle, which resembles trembling or flickering.

Most often, such a pathology is observed only in the area of the atria; only individual impulses can leak to the ventricles, which causes inconsistency in the contractile work of the entire heart. However, most experts consider limiting the impact of excess nerve stimuli on the walls of the ventricles as a certain safety precaution.

The atria are responsible for only 25% of all pumped blood, which allows the body to compensate for such a disruption in hemodynamics with certain difficulties. Ventricular fibrillation most often causes the death of the patient, since the symptoms of circulatory failure in this case will be of a landslide nature.

Classifications of atrial dysfunction

Modern clinical cardiology prefers to distinguish two main ones. ECG diagnosis of atrial fibrillation is based on the principles of this division.

It is believed that the main course of cardiac arrhythmia in the atria is a permanent form of the disease, which occurs in more than 70% of patients and often occurs without pronounced symptoms. Persistent atrial fibrillation is classified by the number of heartbeats and the interaction of the atria and ventricles. There are three main types of disease:

Bradysystolic atrial fibrillation is characterized by a reduced number of heart contractions - less than 60 beats per minute. This pathology most often develops in patients with chronic processes in the heart muscle or coronary vessels.
Normosystolic form of atrial fibrillation It is interesting in that since the number of heartbeats is close to normal and there is no discrepancy in the functioning of the atria and ventricles, the patient may not notice a disruption in the activity of the heart for a long time. The body adapts to minimal hemodynamic disturbances and corrects it itself.
If the number of heart contractions exceeds 100 beats per minute, experts talk about the development of the tachysystolic form of the disease. Such symptoms are most often caused by various acute processes in the human body. Such a heart rhythm disturbance can occur even in a healthy person under the influence of acute poisoning, large amounts of alcohol, or a chronic lack of calcium in the blood.

In clinical practice, a picture is often observed when disruption of the atria occurs without any apparent reason or under the influence of physical activity. In this case, experts talk about the development of a paroxysmal form of atrial fibrillation.

Unlike a constant change in heart rhythm, such attacks are short: they can last from a few seconds to 10 - 12 hours. In terms of symptoms, this disease is similar to the tachysystolic form of rhythm disturbance, but there are certain differences.

If a patient has developed paroxysmal atrial fibrillation, an ECG can clearly diagnose the process. Cardiologists consider the main sign of this pathology to be the presence of specific F waves on the electrocardiogram; an excessive frequency of ventricular complexes on the film is also possible.

Such subtleties of deciphering the electrocardiogram are most needed by emergency doctors and intensive care unit specialists. Regular users of medical websites should note for themselves the main features of what atrial fibrillation looks like on an ECG.

The main thing on the film is the pulse deficiency, that is, the discrepancy between heart contractions and the peristalsis of large vessels and the periphery. As mentioned above, under the influence of excess impulses, the rhythm is disrupted, the frequency of contractions of the atria, and sometimes the ventricles, increases, but the pulse remains unchanged. This occurs for the reason that the innervation of the heart and the rest of the body comes from different sources.

Such observation allows specialists to evaluate the work of the heart only by ECG, since the pulse rate indicators will be unreliable.

Atrial fibrillation is considered a fairly serious disease and should not be treated on its own. The ability to recognize a picture of impaired atrial contractility on an ECG is not a reason to refuse consultation with a specialist. Only a doctor can determine the presence of pathology and prescribe correct and timely treatment.

Research methods and their description

Arrhythmia is considered a common disease among adolescents during puberty. The disease is defined by the following symptoms: chest pain, tachycardia, shortness of breath and others.

Sinus arrhythmia is an uneven distribution of the rhythm, in which it becomes more frequent or less frequent. To determine the cause of the disease, research is necessary.

It happens that a situation arises when an in-depth study may be needed; a person may be prescribed invasive methods - that is, with penetration into the esophagus, blood vessels or heart.

Exercise tests

In order to detect sinus arrhythmia during physical activity, it is most often used bicycle ergometry, treadmill test or tilt test.

Reference! Before starting the research, a blood test is taken, since the first signs of rhythm disturbance can be detected there.

Bicycle ergometry

As the name suggests, the procedure is carried out using a structure that resembles an exercise bike with an attached apparatus. First, the indicators before the procedure are recorded - blood pressure is measured, ECG and heart rate are recorded. The patient begins to pedal at the speed and power set by the doctor. Then the specialist increases the indicators. During the entire procedure, ECG indicators are recorded, and blood pressure is measured every 2-3 minutes. The moment when the patient stops pedaling and rests is also recorded. It is important to understand how quickly the heart returns to a normal rhythm.

Treadmill test

This procedure is also associated with the simulator. The patient walks on a treadmill at different speeds. The intensity is adjusted by changing the speed and angle of inclination.

Also, all indicators are recorded while driving. There are no significant differences from bicycle ergometry. But it is believed that the treadmill is more natural and familiar to the patient.

If any discomfort occurs, the patient can stop. The doctor also closely monitors the patient's condition.

Tilt test

To perform this procedure, the patient is placed on a special table, then he is secured with straps and placed in an upright position. During the change of positions, all ECG readings, as well as blood pressure, are recorded.

Event monitoring

A special device is attached to the patient, but he turns it on only when he feels pain or any discomfort. The received recordings are transmitted to the doctor on the phone.

ECG

ECG is the most important research method through which abnormalities can be detected. This can be determined by the following indicators:

what is the heart rate per minute - bracardia is less than 60, tachycardia is more than 90, and the norm is in the range from 60 to 90;
where is the source of rhythm located? If everything is normal, then it is located in the sinus node;
where the presence and location of extraordinary excitations of the myocardium is extrasystal;
where conduction from the sinus node is impaired, inside the ventricles, or the problem lies in the atrium;
whether there are fibrillations and flutters in the ventricles or in the atrium.

During the procedure, the patient must undress to the waist, free his legs and lie down on the couch. The nurse then applies the product to the lead sites and attaches the electrodes. The wires go to the device and a cardiogram is taken.

Anticipate the presence of sinus arrhythmia on the cardiogram can be done as follows:

You can see the P wave in all leads, while it is always positive in lead II, and vice versa negative in lead aVR, while the electrical axis is within age limits.
Next, you should pay attention to changes in the R-R intervals. Usually the intervals between the teeth are shortened and lengthened smoothly, but if there is a sinus arrhythmia, then abrupt changes are observed.
Again, if there is no difference when holding the breath at the R-R interval, then this indicates an arrhythmia. The exception is older people.

Holter ECG

A device is attached to the patient's body - halter, which records indicators for forty-eight hours. In this case, the person should keep a diary describing their daily activities and symptoms. After which the doctor must analyze the obtained indicators.

This diagnosis allows you to accurately identify the presence of the disease by monitoring the work of the heart over a certain period of time.

But it is worth taking into account the fact that the device may have some malfunctions, so the indicators in some places may not be accurate or may have some deviations.

Electrophysiological study

This method is used if discomfort could not be detected during other studies. One of the electrodes is inserted through the nose into the food passage or a vein is catheterized into the heart cavity. After which a small impulse is given, and the doctor monitors the change in rhythm.

Useful video

The following video lessons will help you learn how to decipher ECG results yourself:

Conclusion

Paying close attention to your heart's function can protect against more serious illnesses. If shortness of breath or rapid heartbeat occurs, it is recommended to immediately consult a doctor. As was described in the article, an ECG is one of the most accurate ways to detect sinus arrhythmia; you can read the cardiogram yourself, but for an accurate diagnosis it is recommended to consult a specialist.

In contact with

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:

Automatism, caused by the spontaneous generation of impulses, which then cause its excitement;
Excitability or the ability of the heart to become active under the influence of exciting impulses;
Conductivity 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) in it are formed under the influence of exciting impulses.

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 during the entire cardiac cycle and repeated depolarizations (excitation, then contraction) and repolarizations (transition to the original state).

Excitation, spreading through the conduction 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.

What does atrial fibrillation look like on an ECG?

Based on the ECG results, the doctor will be able to identify the cause of the arrhythmia.

There are a great number of factors that cause manifestations of arrhythmia, ranging from a neuropsychiatric disorder to severe organic damage to the heart. There are main groups of etiological factors:

Organic or functional diseases of the cardiovascular system (myocardial infarction, ischemic heart disease, pericarditis).
Extracardiac factors – nervous regulation disorders, stress conditions, hormonal disorders.
Bad habits – alcohol abuse, smoking, drug addiction.
Traumatic injuries, hypothermia or, conversely, overheating, oxygen deficiency.
Taking certain types of medications - diuretics, cardiac glycosides as side effects causes arrhythmia.
Idiopathic (independent) arrhythmias - in this case there are no changes in the heart, arrhythmia acts as an independent disease.

Sinus arrhythmia

The heart rhythm is characterized by a period of acceleration and deceleration. The cause of the rhythm disturbance is a change in the tone of the n.vagus during inhalation and exhalation, a violation of the formation of an impulse in the node, or a syndrome of autonomic dysfunction.

On the ECG, sinus arrhythmia is recorded as fluctuations in the intervals between the R waves; with an interval of more than 0.15 seconds, the rhythm becomes irregular. Does not require special therapy.

The diagnosis of sinus tachycardia is made when the heart rate is above 90 beats per minute in a relaxed state (outside physical activity). The sinus rhythm is maintained in the correct form.

The ECG shows up as an accelerated heart rate. The causes of this condition are divided into extracardiac (hypothyroidism, anemia, fever) and intracardial (MI, heart failure). Therapy is aimed at the underlying disease that caused the condition.

Sinus bradycardia is characterized by a regular but slow sinus rhythm (less than 65 beats per minute).

The ECG is characterized by a slower rhythm. The extracardiac form of sinus bradycardia is caused by a toxic effect on the sinoatrial node or the predominance of the parasympathetic system in the regulation of rhythm. Occurs with an overdose of β-blockers, cardiac glycosides; viral hepatitis, influenza; hypothyroidism.

Extrasystole

This type of rhythm disturbance is associated with extraordinary contractions of the entire heart muscle or some part, which is caused by a spontaneous electrical impulse from the atria or ventricles. This type of arrhythmia is a rather dangerous condition, especially when it is group, as it can develop into ventricular fibrillation or ventricular tachycardia.

The ECG shows a premature ventricular or atrial complex while maintaining a normal further rhythm. If an early extrasystole is recorded, it can be superimposed on the top of the tooth of the previous complex, due to which deformation and expansion of the latter is possible. At the end of the extrasystole, a compensatory pause always occurs - the next P-QRST cycle is delayed.

Impulse conduction disorders in paroxysmal tachycardia

The clinical picture is similar to an extrasystole, it also begins suddenly and ends quickly, the difference is in the heart rate, reaching up to 240 beats per minute in the atrial form and impaired hemodynamics in the ventricular form.

The ECG shows an altered P wave, which precedes the QRS complex, the P-R interval is lengthened, and the ST complex is subject to secondary changes. Before an attack, ventricular or supraventricular extrasystoles and impulse conduction disturbances may be recorded on the cardiogram.

The second name is blockade. According to the place of origin they are divided into:

Sinoatrial block - impulses from the sinoatrial node do not enter the atria, which is typical for structural damage to the heart. Therapy is aimed at the underlying disease.
Intraatrial block is detected in heart defects, myocardial inflammation, coronary heart disease, as well as in case of poisoning of certain antiarrhythmic drugs.
Atrioventricular (AV) block is a delay in the conduction of impulses from the atrium to the ventricle. Occurs during inflammatory and destructive processes in the heart, myocardial infarction. Increased irritation of the vagus also plays a role in the occurrence of AV block;
Intraventricular blockade - occurs in the conduction system of the heart (disorders in the His bundle, blockade of the right and left legs of the bundle of His). This type of blockade does not require special therapy.
Wolff-Parkinson-White syndrome or premature ventricular depolarization. It develops when additional pathways appear. More often affects men than women. A separate syndrome does not require treatment; in some cases, when combined with paroxysmal tachycardia, β-blockers, cardiac glycosides, are prescribed.

On the ECG, these types of arrhythmia are characterized by loss of contractions of the ventricles and atria (PQRS complex), a predominance of P waves, and deformation of the ventricular complexes.

In terms of frequency of occurrence, atrial fibrillation ranks after extrasystolic arrhythmia. It is characterized by the fact that excitation and contraction occur only in certain places of the atria, while in general there is no general excitation. This phenomenon prevents the conduction of an electrical impulse to the AV node.

The ECG is characterized by two characteristic changes: the absence of the P wave (the atria are not excited, instead there are atrial waves), and a different interval between the QRS complex.

Atrial fibrillation is a rhythm disorder in which, during one cardiac cycle, random excitation and contraction of individual atrium muscle fibers occurs.

Heart diseases require a comprehensive study. These include cardiac arrhythmia. The first diagnostic test to which the cardiologist refers the patient is an ECG.

On an electrocardiogram, the bioelectric activity of the heart is reflected in the form of teeth, intervals and sections. Their length, width, and distance between the teeth normally have certain values. Changing these parameters allows the doctor to determine abnormalities in the functioning of the heart muscle.

In most cases, it is enough to conduct an ECG so that the cardiologist can correctly diagnose the patient. Additional types of research are carried out to determine the type of pathological process.

Changes in the ECG make it possible to determine whether the patient is suffering from atrial fibrillation (atrial fibrillation) or flutter. Decoding the result will make it clear exactly what is bothering the patient. Atrial flutter is characterized by a rapid but regular rhythm of heart contractions, while with fibrillation the rhythm is disturbed, different groups of muscle fibers in the atria contract inconsistently with each other.

First signs

The electrocardiogram shows signs characteristic of the disease. Atrial fibrillation on an ECG will look like this:

There is no P wave on any electrocardiographic lead (this wave is a mandatory component of a normal ECG).
Presence of erratic f waves throughout the entire cardiac cycle. They differ from each other in amplitude and shape. In certain leads these waves are recorded best. These include V1, V2, II, III. aVF. These waves occur as a result of atrial fibrillation.
Irregularity of ventricular R-R complexes (unevenness, different lengths of R-R intervals). It indicates an abnormal ventricular rhythm;
QRS complexes are distinguished by their unchanged appearance and the absence of signs of deformation.

On the ECG, a small- or large-wave form of atrial fibrillation is distinguished (depending on the scale of the f waves).

Chest pain is one of the possible symptoms of atrial fibrillation

Clinical symptoms of atrial fibrillation become more pronounced as the disease progresses. They can vary significantly from patient to patient.

Signs of atrial fibrillation, which appear on the electrocardiogram, are complemented by symptoms that are noticeable to the patient himself. We are talking about such painful conditions:

profuse sweating;
weakness;
cardiopalmus;
chest pain.

A patient with chronic atrial fibrillation may not even be aware of his illness if it is characterized by an asymptomatic course. In this case, only the result of an electrocardiographic study can determine the presence of pathology.

The types of electrocardiographic manifestations, that is, the symptoms that are visible on the ECG, correspond to the clinical signs of the disease in the patient. Thanks to this, a competent specialist is able to accurately understand what exactly is bothering the patient and what kind of help he needs to provide.

Atrial fibrillation is a severe pathology; it has a significant cause that must be treated along with the arrhythmia itself.

Among the causes of the disease are:

dysfunction in the endocrine system,
atherosclerotic changes in blood vessels,
cardiovascular failure,
disturbances in the body's water-salt balance,
cardiosclerosis,
acid-base balance disorders,
congenital or acquired heart defects,
cardiomyopathy,
hypertension,
neoplasms of the heart,
renal failure,
surgical interventions on the heart and blood vessels,
myocarditis.

The cause of the disease can be determined after a comprehensive examination of the patient, and an ECG for atrial fibrillation will play an important role in this matter - the doctor will notice the characteristic signs of pathology on it.

When interpreting the electrocardiogram of patients with suspected atrial fibrillation, doctors pay attention to the following analysis features:

Absence of P-wave at abduction sites.
The presence of atrial fibrillation waves, which are frequent and irregular, which is provoked by chaotic excitation and atrial contractions. There are large-wave and small-wave forms of f-wave amplitude. The large-wave form with an indicator of more than one millimeter is observed in people suffering from chronic pulmonary heart disease, as well as in those who suffer from mitral stenosis. The shallow-wave form is characteristic of patients with myocarditis, myocardial infarction, thyrotoxicosis, intoxication, and cardiosclerosis.

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.

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.

ECG analysis

A more rigorous interpretation of the ECG is made by analyzing and calculating the area of the teeth using special leads (vector theory), however, in practice, they mainly make do with such an indicator as the direction of the electrical axis, which represents 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 ischemic heart disease, atherosclerosis, myocarditis, rheumatism. 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;
The position of the EOS begins to be calculated from the isoline along 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.

Ventricular fibrillation

The ECG is displayed as a wave of one amplitude, on which it is impossible to distinguish complexes and waves, the rhythm frequency is 250-300 beats per minute. There is no clear isoline.

The most disappointing diagnosis: heart attack

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

The classic signs of myocardial infarction on the ECG are the registration of a deep Q wave (OS), an elevation of the ST segment, which deforms the R, smoothing it, and the subsequent appearance of a negative pointed isosceles wave 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.

Myocardial infarction is a severe complication of cardiac pathologies (hypertension, arrhythmia). Symptoms of a heart attack are often similar to those of acute angina, but are difficult to control with medications. With this pathology, the blood flow changes, causing the death of heart tissue. The patient needs urgent medical attention. At the first opportunity, he is shown electrocardiography.

Cardiogram of the heart

Human organs emit weak currents. This ability is used in the operation of an electrocardiograph, a device that records electrical impulses. The device is equipped with:

a mechanism that enhances weak currents;
voltage measuring device;
recording device (works in automatic mode).

Based on the cardiogram generated by the device, the doctor makes a diagnosis. Special tissue of the human heart (the conduction system) transmits signals to the muscle about relaxation and contraction. Heart cells respond to signals, and the cardiograph records them. The electric current in the heart cells passes through the periods:

depolarization (changing the negative charge of cardiac muscle cells to positive);
repolarization (restoration of negative intracellular charge).

The electrical conductivity of damaged cells is significantly lower than that of healthy cells. This difference is recorded on the cardiogram.

To decipher the confusing graphs that come out from under the cardiograph recorder, you need to know some subtleties. The intervals and waves are clearly visible on the cardiogram. They are designated by the letters P, T, S, R, Q and U. Each element of the graph reflects the work of one or another part of the heart. In the diagnosis of pathology, the following are “involved”:

Q – tissue irritation between the ventricles;
R – irritation of the apex of the heart muscle;
S – irritation of the ventricular walls; normally has a vector inverse to vector R;
T – “rest” of the ventricles;
ST – “rest” period.

Typically, twelve recording electrodes are used to take a cardiac cardiogram. In case of a heart attack, the data from the electrodes on the left side of the chest (V1-V6) are significant.

Doctors “read” the electrocardiogram by measuring the length of the intervals between oscillations. The data obtained allows you to analyze the rhythm, and the teeth reflect the strength of heart contractions. There is an algorithm for determining the norm and violations:

Analysis of heart rhythm and contraction readings;
Calculation of time intervals;
Calculation of the electrical axis of the heart;
Study of the QRS complex;
ST segment analysis.

Important! Non-ST segment elevation myocardial infarction can occur due to rupture of a cholesterol plaque. Platelets deposited on the plaque activate the coagulation system, and a blood clot forms. An inflammatory process can also lead to plaque rupture.

During a heart attack, sections of the myocardium die due to insufficient blood supply. The heart tissues become deficient in oxygen and nutrients and cease to perform their function. The heart attack itself consists of three zones:

ischemia (initial degree, repolarization processes are disrupted);
zone of damage (deeper disturbances, depolarization and repolarization processes are disrupted);
necrosis (tissues begin to die, the processes of repolarization and depolarization are completely absent).

Experts note several types of necrosis:

subendocardial (on the inside);
subepicardial (outside, in contact with the outer membrane)
intramural (inside the ventricular wall, not in contact with the membranes);
transmural (throughout the entire volume of the wall).

ECG signs of myocardial infarction:

the frequency of contractions of the heart muscle increases;
The ST segment rises, its stable depression is observed;
QRS duration increases;
The R wave changes.

The pathology that caused the change

Characteristic signs

	Normal heart function	The ST segment and waves are normal.
	Subendocardial ischemia	Repolarization disorder – high pointed T wave.
	Subepicardial ischemia	T wave negative
	Transmural ischemia	Deep negative T wave
	Subendocardial damage	The ST segment changes - either rises or falls (depression)
	Subepicardial damage	ST segment elevation
	Subepicardial ischemia subendocardial injury	ST segment depression and negative T wave
	Subepicardial injury subepicardial ischemia	ST segment elevation and negative T wave
	Transmural damage	The elevation of the ST segment is more noticeable than with subepicardial damage, reaches the T wave in height and is combined with it in one line. The complex is popularly called “cat’s back”. It is registered at the initial stages of pathology, in its most acute stage.
	Transmural infarction	There is no depolarization or repolarization. Only the Q wave is recorded under the electrode - deep and combined with the S wave, therefore it is also called the QS wave
	Nontransmural infarction	“Irregular” Q wave, almost equal in size to the R wave (it is not high, because only part of the wall is repolarized)
	Non-transmural infarction, subepicardial ischemia	Pathological Q, reduced R wave, negative T. Normal ST segment
	Subendocardial infarction (non-Q) subendocardial injury	Necrosis does not penetrate into the myocardium (a thin strip lies under the endocardium). The R wave is reduced, the ST segment is depressed

Important! Intramural infarction (not Q) occurs within the myocardial wall. Depolarization bypasses it on both sides, so the Q wave is usually not recorded.

There are several stages of necrosis:

damage (acute) – up to three days;
acute – up to three weeks;
subacute – up to three months;
scarring - for the rest of life.

Heart attack stage

Graphic image on a cardiogram

Characteristic signs

Acute	At first:	A zone of necrosis begins to form. A “cat’s back” appears. At the first signs of necrosis, a Q wave is recorded. The ST segment may be located below or above
Acute	At first:	The damaged zone is gradually replaced by an ischemic zone. The necrosis zone grows. As the infarction progresses, the ST segment decreases. Due to ischemia, a negative T wave remains. By the beginning of a new stage, the damage zone disappears
Subacute		The Q wave and the reduced R wave are recorded. The ST segment lies on the isoline. A deep negative T wave indicates a large ischemic area
Scarring		Necrosis develops into a scar surrounded by normal tissue. On the cardiogram, only the pathological Q wave is recorded. R wave is reduced, the ST segment lies on the isoline. T is normal. Q remains for life after a myocardial infarction. Can be “masked” due to changes in the myocardium

Important! In most populated areas, you can take an ECG at home by calling an ambulance. A portable electrocardiograph can be found in almost every emergency vehicle.

Doctors find the heart attack area by identifying organ tissue visible on the ECG leads:

V1-V3 – ventricular wall in front and tissues between the ventricles;
V3-V4 – ventricles (front);
I, aVL, V5, V6 – left ventricle (left front);
I, II, aVL, V5, V6 – ventricle (top, front);
I, aVL, V1-V6 – significant anterior lesion;
II, III, aVF – ventricles (posteriorly from below);
II, III, aVF, V3-V6 – left ventricle (top).

These are not all possible areas of damage, because localization of myocardial infarction can be observed both in the right ventricle and in the posterior parts of the heart muscle. When deciphering, it is necessary to have maximum information from all electrodes, then the localization of myocardial infarction by ECG will be more adequate.

The area of damaged lesions is also analyzed. The electrodes “shoot” into the heart muscle from 12 points, the “shooting” lines converge in its center. If the right side of the body is examined, six more leads are added to the standard ones. When deciphering, special attention is paid to data from electrodes near the area of necrosis.

Parasystole of the heart

Often in ECG conclusions you can find the expression: “Left ventricular hypertrophy.” 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

In medical practice, the term “parasystole” is practically not used. Translated from Latin, it means independent contraction of the heart, independent of the main pacemaker.

The fact is that any extraordinary sources require clarification. Arrhythmias have their own origin and mechanism of development. The word “parasystole” is also found in popular literature as a collective name for rhythm disturbances associated with additional ectopic (heterotopic) foci.

Classifications of arrhythmias are based on different characteristics, each with its own disadvantages:

according to the anatomical location of the ectopic focus - the mechanism of development of disorders is not taken into account;
according to the mechanism of violation of automaticity, conductivity or excitability - in most cases there is a violation of all functions at once;
by rhythm frequency - with the diagnosis of normo-, tachy- and bradyarrhythmia, the algorithm for determining the type begins, but it requires further clarification using electrocardiographic (ECG) studies;
depending on the mechanism of impulse occurrence (in a normal and ectopic focus) - separate identification of conduction disorders and combined disorders.

Parasystole is closest to the last option. Let us clarify that we understand the term as additional contractions of the heart muscle in response to impulses coming from the “paracenter” located in any part of the heart.

Automatic generation of impulses is a physiological function of myocardial cells. This is how they differ from ordinary muscle tissue. Typically the impulses originate in the sinus node. From here they spread to all parts of the heart and cause the correct rhythm.

The parasystolic center may arise elsewhere and contribute to premature contractions, extrasystoles, or a more complex disorder - atrial fibrillation.

Increased tone of the vagus nerve is important. This mechanism predominates in healthy people and athletes.

There is a possibility of internal blockade of the propagation of ectopic waves. But with a weak sinus node, the parasystolic focus turns out to be active. Usually the impulse with the highest frequency “wins”.

Depending on the location of the source of the second rhythm, the following types are distinguished:

ventricular parasystole;
atrial;
from the atrioventricular node;
polytopic (from different places).

In addition, in relation to the normal contraction, extrasystole can be:

early and late;
single, group and allorhythmic (constant rhythmic alternation).

According to the frequency of the ectopic rhythm:

rare (up to 10 per minute);
medium (10–30);
frequent (more than 30).

There are temporary and permanent forms. The type of parasystole can be clarified using the ECG picture.

There are cardiac and extracardiac causes. In some cases, it is impossible to establish a connection with any cause, then the extrasystole is called idiopathic.

Cardiac ones include:

ischemia or necrosis in the sinus node area and other places with coronary heart disease, which forces different areas to become active and “survive” on their own;
inflammation of a focal or diffuse nature in acute and chronic myocarditis (rheumatic carditis, acute infectious diseases, sepsis);
metabolic changes during dystrophy;
replacement of myocytes with connective tissue cells with disruption of their functions (cardiomyopathies, cardiosclerosis);
loss of the ability to restore the required level of energy (circulatory failure);
hypertrophy of myocardial tissue (hypertension, decompensation in heart failure, cardiomyopathies);
disruption of the valves (congenital malformations, acquired changes in the valves due to inflammatory processes, injuries).

Non-cardiac causes include concomitant diseases leading secondary to myocardial dysfunction. Most often, these changes are “guided” by endocrine organs when:

diseases of the thyroid gland (hypothyroidism or hyperthyroidism associated with deficiency or excess synthesis of thyroid hormones);
diseases of the adrenal glands;
diabetes mellitus

Activation of parasystolic foci is detected on the ECG when:

vegetative-vascular dystonia, neuroses;
anemia (anemia) of various origins;
overdose of drugs (cardiac glycosides);
violation of the necessary balance in the electrolyte composition of the blood between potassium, sodium, magnesium and calcium, they are necessary for the implementation of the normal process of excitation and contraction of myocardial cells.

Clinical signs of parasystole are felt by a person as:

strong “blows or jolts” to the chest;
“heart stop”, “fading”;
attacks of sudden heart palpitations.

Common symptoms include: dizziness, weakness, fainting, coughing movements.

Extrasystoles may not give any symptoms and are detected during examination by chance.

The patient must undergo a general appointment with a therapist. The doctor will try to find out the connection between parasystole and other diseases and will discover a hidden course. It is necessary to talk about your feelings and their dependence on a specific reason.

If the patient is taking medications, it is necessary to reconsider their appropriateness and the possibility of affecting the heart rhythm.

Family history is always taken into account - the tendency of relatives to similar diseases.

Auscultation of the patient allows you to identify arrhythmia and calculate the number of heartbeats. Hypertension at the appointment indicates the role of increased pressure in myocardial tension.

General blood tests and biochemical tests are carried out to more accurately identify the mechanism of disorders:

Reduced hemoglobin and red blood cells indicate anemia.
An altered balance of cholesterol, triglycerides and lipoproteins suggests the development of atherosclerosis in the vessels of the heart.
Blood glucose level is the primary diagnosis of diabetes mellitus.
Determination of electrolyte composition shows nutritional deficiencies.

Sometimes the patient is prescribed more in-depth studies of hormonal levels, and consultation with an endocrinologist is recommended.

To identify cardiac causes, a complete examination is necessary, including differential diagnosis of defects, physiological abnormalities, and the consequences of vascular atherosclerosis.

The ECG quite accurately shows the localization of the second pacemaker, allows you to distinguish the ventricular type from others, and identify allorhythmia. This method is available at the outpatient and clinic level. Allows you to identify signs of heart disease that cause rhythm changes. Conducting stress tests is recommended to identify the latent form (asymptomatic), the connection with physical activity and the influence of nervous regulation. Bicycle ergometry tests, treadmill walking, and stair tests are used.
If parasystoles appear rarely, then the Holter monitoring method helps: the patient is fitted with electrodes for a day, from which information is recorded even during night sleep. Decoding allows you to determine the cause of the extrasystole.
Dopplerography is a very informative method for identifying heart defects, the degree of mitral valve prolapse, and myocardial reserve reserves. The image on the screen visualizes the contraction process and its phases. At the same time, a quantitative analysis of indicators is carried out.
Magnetic resonance imaging (MRI) is the method of choice for diagnosing the correct functioning of all parts of the heart muscle and identifying replacement with scar tissue.

Treatment

After identifying the disease that caused parasystole, you should carefully follow the cardiologist’s recommendations on regimen and treatment. In each specific case, different medications are prescribed, so you should not adopt the experience of neighbors or acquaintances.

In your daily routine, it is imperative to allocate enough time for rest, relaxation, exercise, and sleep.

Treatment will not be successful if you abuse alcoholic beverages (including beer) or smoke. You will have to get rid of these habits.

There is no special diet in nutrition, but nutritionists recommend eliminating strong irritants from food:

fried and smoked meat dishes;
high-fat dairy products;
butter and animal fats;
strong tea and coffee;
spicy seasonings and sauces.

You should not overeat; it is better to eat often, but in small portions. Preference is given to boiled and steamed fish, poultry, fresh vegetables and fruits.

For drug treatment use:

Soothing herbal remedies made from mint, valerian, motherwort. If necessary, the doctor prescribes sedatives.
To improve metabolism in myocardial cells, Retabolil, Panangin, Riboxin are prescribed.
For high concentrations of low-density lipoproteins, statins and nicotinic acid injections are recommended.
β-blockers (Isoptin, Obzidan) are prescribed for organic changes to suppress impulse transmission from paracentres.

Surgical methods are used when drug therapy is unsuccessful or it is impossible to use them (pregnancy). The least dangerous method is radiofrequency ablation of the source of excitation. A catheter with a radiofrequency emitter at the end is brought to the heart through large vessels. The end of the catheter is placed in the area of suspected heterotopic foci and their targeted destruction is carried out. A scar forms at the site of exposure.

The most dangerous consequences of uncontrolled parasystole can be:

ventricular fibrillation, leading to death;
the formation of chronic heart failure with a gradual decline in the ability of the heart muscle to contract and push blood.

Clinicians and scientists study heterotopic foci (parasystolic) in the heart. The impact of altered neurohormonal regulation on the heart is well recognized. This process is especially important during the period of child growth, adolescence, and menopause. A person should pay the most attention to health during these sensitive periods of life.

Holter method

In standard situations, a person is diagnosed with atrial fibrillation based on his complaints and the symptoms of the disease identified during the initial diagnosis. A survey of the patient and the results of electrocardiographic diagnostics are quite sufficient if there are no serious complications of the disease.

If the ECG does not provide sufficient information about the patient’s condition, the cardiologist will refer him for additional studies:

Echocardioscopy.
Radiography.
Biochemical tests of blood and urine.
Transesophageal examination of the cardiac conduction system.

An important stage in the study of a patient with atrial fibrillation is differential diagnosis: it is necessary to distinguish the disease from other pathological conditions that may have similar symptoms. Differential diagnosis is carried out with the following pathologies:

sinus tachycardia;
atrial flutter;
supraventricular paroxysmal tachycardia;
ventricular paroxysmal tachycardia.

ECG results allow the cardiologist to distinguish atrial fibrillation from the above-mentioned heart diseases.

HM ECG - what kind of abbreviation is this so incomprehensible? This is the name for long-term and continuous recording of an electrocardiogram using a portable portable tape recorder, which records the ECG on magnetic tape (Holter method). Such electrocardiography is used to detect and register various disorders that occur periodically, so a regular ECG is not always able to recognize them.

In addition, abnormalities may occur at certain times or under certain conditions, so in order to compare these parameters with the ECG recording, the patient keeps a very detailed diary. In it, he describes his feelings, records the time of rest, sleep, wakefulness, any active activity, notes the symptoms and manifestations of the disease.

The duration of such monitoring depends on the purpose for which the study was prescribed, however, since the most common is recording an ECG during the day, it is called daily, although modern equipment allows monitoring for up to 3 days. And a device implanted under the skin takes even longer.

Daily Holter monitoring is prescribed for rhythm and conduction disorders, painless forms of coronary heart disease, Prinzmetal's angina and other pathological conditions. Also, indications for the use of Holter are the presence of an artificial pacemaker in the patient (control over its functioning) and the use of antiarrhythmic drugs and drugs for the treatment of ischemia.

Preparing for Holter monitoring is also simple, but men should shave the electrode sites, as hair will distort the recording. Although it is believed that daily monitoring does not require special preparation, the patient, as a rule, is informed what he can and cannot do.

Of course, you cannot immerse yourself in a bath; the device does not like water procedures. There are those who don’t even accept showers, all you have to do is endure, unfortunately. The device is sensitive to magnets, microwaves, metal detectors and high-voltage lines, so it is better not to test its strength; it will still record incorrectly. He doesn’t like synthetics and all kinds of metal jewelry, so he should switch to cotton clothes for a while and forget about jewelry.

Bicycle and ECG

Everyone has heard something about such a bicycle, but not everyone has ridden it (and not everyone can). The fact is that hidden forms of coronary circulatory insufficiency, excitability and conduction disorders are poorly detected on an ECG taken at rest, therefore it is customary to use the so-called bicycle ergometer test, in which the cardiogram is recorded using dosed increasing (sometimes constant) loads. During an ECG with stress, the patient's overall response to this procedure, blood pressure and pulse are simultaneously monitored.

A bicycle ergometer test is prescribed if necessary:

To clarify the diagnosis of coronary heart disease, rhythm and conduction disorders that occur in a latent form;
To evaluate the effectiveness of treatment of coronary heart disease;
Select medications for an established diagnosis of IHD;
Select training regimes and loads during the period rehabilitation of patients who have had myocardial infarction (before the expiration of a month from the onset of MI, this is possible only in specialized clinics!);
To provide a prognostic assessment of the condition of patients suffering from coronary heart disease.

However, performing an ECG with a load also has its contraindications, in particular, suspicion of myocardial infarction, angina pectoris, aortic aneurysms, some extrasystoles, chronic heart failure at a certain stage, cerebrovascular accident and thrombophlebitis are an obstacle to the test. These contraindications are absolute.

In addition, there are a number of relative contraindications: some heart defects, arterial hypertension, paroxysmal tachycardia, frequent extrasystole, atrioventricular block, etc.

What is phonocardiography?

FCG or phonocardiographic research method allows the sound symptoms of the heart to be depicted graphically, to objectify it and to correctly correlate tones and noises (their shapes and duration) with the phases of the cardiac cycle. In addition, phonography helps in determining some time intervals, for example, Q - I sound, the sound of the mitral valve opening - II sound, etc. During PCG, an electrocardiogram is also recorded simultaneously (a mandatory condition).

The phonocardiography method is simple; modern devices make it possible to isolate high- and low-frequency components of sounds and present them as most convenient for the researcher’s perception (comparable to auscultation). But in capturing pathological noise, FCG is not superior to the auscultatory method, since it does not have greater sensitivity, so it still does not replace a doctor with a phonendoscope.

Phonocardiography is prescribed in cases where it is necessary to clarify the origin of heart murmurs or the diagnosis of valvular heart defects, to determine indications for surgical intervention for heart defects, and also if unusual auscultatory symptoms appear after myocardial infarction.

A dynamic study using PCG is needed in cases of active rheumatic carditis to clarify the pattern of formation of heart defects, and in infective endocarditis.

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Purpose of the lesson: To teach clinical and ECG diagnostics of the main types of heart rhythm disturbances.

By the end of the lesson, the student should know:

Classification of arrhythmias.

Arrhythmias associated with dysfunction of automaticity.

Arrhythmias associated with dysfunction of excitability.

Arrhythmias associated with conduction dysfunction.

Complex types of heart rhythm disorders.

As a result of the lesson, the student should be able to:

Correctly recognize different types of arrhythmias based on clinical signs.

Correctly recognize different types of arrhythmias using ECG.

Motivation. Arrhythmias are a common complication of heart disease. They aggravate the course of the disease. Therefore, timely accurate diagnosis of arrhythmias is important for the treatment of patients.

Initial data.

Educational elements.

Basic functions of the heart . The work of the heart is carried out thanks to 4 main functions: automaticity, excitability, conductivity, contractility.

Classification of heart rhythm disorders . Arrhythmias are divided into groups depending on the disturbance of one or another function of the heart: automaticity, excitability, conductivity and contractility.

Automatic dysfunction. The most common are sinus tachycardia, sinus bradycardia and sinus arrhythmia. On an ECG, a sign of sinus rhythm is the presence of a positive P wave before the QRS complex.

Sinus tachycardia . Caused by increased activity of the sinus node as a result of physical or nervous stress, fever, when taking stimulants, thyrotoxicosis, heart failure. Patients complain of palpitations, the pulse is frequent and rhythmic. On the ECG, the RR and TP intervals are shortened.

Sinus bradycardia . It is caused by the rare generation of impulses from the sinus node. It is observed in cases of hypothyroidism, the effect of a number of medications, with increased tone of the vagus nerve during sleep, in patients with liver and gastrointestinal diseases, and in athletes. The pulse is rhythmic and rare. On the ECG, the RR and TP intervals are prolonged.

Sinus arrhythmia . It is caused by the irregular production of impulses from the sinus node. There are 2 forms: respiratory (adolescent) and non-respiratory (for myocardial diseases). The ECG shows different durations of RR intervals in sinus rhythm.

Violation of excitability function. Manifested by extrasystole and paroxysmal tachycardia. It is caused by the appearance in some areas of the myocardium of ectopic foci of excitation, which can generate an impulse leading to an extraordinary contraction of the heart. Such heterotopic foci occur in myocardial diseases, with an overdose of a number of medications, with increased nervous excitability, etc.

Diagnostic signs of extrasystole :

extraordinary reduction;

complete or incomplete compensatory pause;

drawing of the extrasystolic complex on the ECG.

In addition to single ones, there are group extrasystoles, and sometimes there is a pattern of extrasystoles, which is called allorhythmia. The types of allorhythms are as follows:

bigeminy (extrasystoles are repeated after each normal sinus complex);

trigeminy (every two sinus complexes are followed by extrasystole);

quadrigeminy (every three normal cycles are followed by an extrasystole).

Atrial extrasystole . The ectopic focus of excitation is located in the atrium. In this case, excitation to the ventricles spreads in the usual way, therefore the ventricular QRS-T complex will not be changed, some changes in the P wave may be observed. The compensatory pause is incomplete, since at the moment of generation of the ectopic impulse the sinus node is discharged, and after the extrasystole the next normal complex goes through the normal time interval.

Atrioventricular extrasystole . In this case, an extraordinary impulse leaves the atrioventricular node. Excitation covers the ventricles in the usual way, so the QRS complex is not changed. In the atria, excitation goes from bottom to top, leading to a negative P wave. Depending on the conditions of impulse conduction in the affected myocardium, excitation may reach the atria earlier and negative P will then be recorded before the normal QRS complex (“upper node” extrasystole). Or the excitation will reach the ventricles earlier, and the atria will be excited later, then the negative P will move after the QRS complex (“inferior nodal” extrasystole). In cases of simultaneous excitation of the atria and ventricles, a layering of negative P on the QRS occurs, which deforms the ventricular complex (“mid-nodal” extrasystole).

Ventricular extrasystole is caused by the release of excitation from an ectopic focus in one of the ventricles. In this case, the ventricle in which the ectopic focus is located is first excited, and the excitation reaches the other later along the Purkinje fibers through the interventricular septum. The impulse does not reach the atria in the opposite direction, therefore the extrasystolic complex does not have a P wave, and the QRS complex is expanded and deformed.

Paroxysmal tachycardia. This is a long chain of extrasystoles, due to the high activity of the ectopic focus, which produces 160-220 or more impulses per minute. The sinus node is suppressed and does not work. There is a supraventricular form of paroxysmal tachycardia (the ectopic focus is in the atrium), when all complexes are of a normal appearance, since excitation to the ventricles proceeds in the usual way from top to bottom. There is a ventricular form of paroxysmal tachycardia (an ectopic focus in one of the ventricles), when all complexes are dilated and deformed due to the simultaneous contraction of the ventricles.

Conduction dysfunction- blockades. A blockade is a slowdown or a complete interruption in the conduction of an impulse, therefore a distinction is made between incomplete and complete blockades. They are caused by a “lack of energy” to conduct impulses in myocardial diseases, the presence of cicatricial, dystrophic, inflammatory changes in the heart muscle.

Sinoauricular block is expressed in the fact that the entire cardiac P-QRS-T cycle periodically drops out, since “energy is quickly consumed” when conducting impulses from the sinus node to the atria.

Intraatrial block noted with an increase in the size of the atria, there is a right atrial (P-pulmonale) and a left atrial (P-mitrale). Due to the fact that the P wave is caused by the excitation of first the right and then the left atrium, with an enlarged right atrium, the P wave increases, becomes high and pointed. With enlargement of the left atrium, the P wave is expanded, often double-humped.

Atrioventricular block divided into 3 degrees.

1st degree manifests itself in prolongation of the PQ interval by more than 0.20 s.

2nd degree atrioventricular block is associated with an even greater slowdown in the conduction of impulses from the atria to the ventricles due to a greater lack of energy. There are 2 types according to Mobitz. With atrioventricular block of the 2nd degree according to the 1st Mobitz type, there is a gradual lengthening of the PQ interval with periodic loss of the ventricular complex - Samoilov-Wenckebach periods.

At 3 degrees There is a complete interruption in the movement of the impulse from the atria to the ventricles. This is a complete transverse block. In this case, the atria work from the sinus node (pacemaker of the 1st order) and the ECG will show rhythmic P waves. The ventricles receive impulses from the atrioventricular node (pacemaker of the 2nd order) or from the branches of the His bundle (pacemaker of the 3rd order), sometimes from Purkinje fibers . Since the underlying pacemakers have less automaticity, the ventricles contract less frequently than the atria, and on the ECG, QRS complexes will be recorded less frequently than P waves. With complete atrioventricular block, the pacemaker for the ventricles periodically changes, which leads to short-term cardiac arrest. Clinically this manifests itself Morgani-Edams-Stokes syndrome. There is a temporary cessation of cardiac activity, loss of consciousness, cyanosis and a seizure. In the treatment of these patients, an artificial pacemaker is used.

Bundle branch block . When one of the His bundle branches is completely blocked, the impulse from the atria passes to the unblocked leg, and to the other ventricle the excitation travels along the Purkinje fibers through the interventricular septum. As a result, the ventricles contract alternately and after the P wave a widened and deformed QRS will be recorded.

Complex rhythm disturbances - atrial fibrillation and atrial flutter. Most often observed in a triad of diseases: mitral stenosis, cardiosclerosis, thyrotoxicosis. In this case, all 4 functions of the heart are disrupted. Initially, the excitability function is impaired, since due to pronounced dystrophic changes in the atria, many ectopic foci with high activity appear. In 1 minute, from 600 to 900 pulses are generated. The sinus node is suppressed and does not work. Due to the very large number of impulses, the atria do not contract, but fibrillar twitching of individual muscle fibers is observed (the atria “flicker”). The atrioventricular node conducts only part of the impulses irregularly, and blocks the majority. The ventricles work irregularly, therefore, with different blood flow and contraction force. Clinical signs: the pulse is irregular and uneven, the heartbeat is irregular with varying volumes of tones.

On ECG atrial fibrillation manifested by 4 signs: different duration of the R-R interval, different heights of the R wave in the same lead, absence of the P wave, the presence of a wavy isoelectric line, especially noticeable in 1-2 chest leads.

Atrial flutter has the same mechanism, but fewer impulses are produced from ectopic foci in the atria (300-400 per minute). Therefore, instead of a wavy isoline, step-like teeth are recorded on it, caused by defective weak contractions of the atria.

Control questions:

List the main functions of the heart.

Explain the classification of heart rhythm disorders.

What are the signs of sinus rhythm on an ECG?

What are the clinical and ECG signs of sinus tachycardia?

What are the clinical and ECG signs of sinus bradycardia?

What are the clinical and ECG signs of sinus arrhythmia?

Define extrasystole.

The mechanism of development of extrasystole.

What are the clinical and ECG signs of different types of extrasystoles?

What is paroxysmal tachycardia?

What is the manifestation of conduction dysfunction?

Describe sinoauricular block.

What is the manifestation of intraatrial block?

What is the manifestation of atrioventricular block?

What degrees of atrioventricular block and their manifestations do you know?

What is the manifestation of bundle branch block?

What cardiac functions are impaired in atrial fibrillation?

What is the mechanism of occurrence of atrial fibrillation?

What are the clinical and ECG signs of atrial fibrillation?

Situational tasks.

Task 1. The patient complains of palpitations. There is a frequent and rhythmic pulse. On the ECG, the R-R and T-P intervals are shortened, a positive P wave precedes the QRS complex.

In medical terms, heart rhythm disturbances are called arrhythmia. Most people understand this term as random abbreviations, but this is not entirely correct. In fact, arrhythmia is an abnormal rhythm, frequency and sequence of heart contractions.

ECG helps diagnose various types of heart rhythm disorders

This disease is diagnosed using an ECG, on the graph of which the doctor sees changes in the length of the segments or the size of the teeth. Unfortunately, the problem of cardiac arrhythmia is one of the main ones in cardiological practice, since it is often difficult to identify the etiological causes of heart failure, and deep skills in deciphering the ECG are also required.

All arrhythmias are associated with a disruption in the functioning of the properties of the heart muscle - automaticity, excitability, conductivity. Depending on which of the properties of the heart is affected, arrhythmias according to the mechanism of occurrence can be divided into three groups:

arrhythmia associated with a violation of the formation of an electrical signal (sinus tachycardia/bradycardia, sinus arrhythmia);
arrhythmia associated with a malfunction in the conduction system of the heart;
combined forms of arrhythmias.

Common causes of rhythm disturbances

Based on the ECG results, the doctor will be able to identify the cause of the arrhythmia.

Organic or functional diseases of the cardiovascular system (myocardial infarction, ischemic heart disease, pericarditis).
Extracardiac factors – nervous regulation disorders, stress conditions, hormonal disorders.
Bad habits – alcohol abuse, smoking, drug addiction.
Traumatic injuries, hypothermia or, conversely, overheating, oxygen deficiency.
Taking certain types of medications - diuretics, cardiac glycosides as side effects causes arrhythmia.
Idiopathic (independent) arrhythmias - in this case there are no changes in the heart, arrhythmia acts as an independent disease.

Arrhythmias caused by a failure in the formation of an electrical impulse

Sinus arrhythmia

Sinus tachycardia

The diagnosis of sinus tachycardia is made when the heart rate is above 90 beats per minute in a relaxed state (outside physical activity). The sinus rhythm is maintained in the correct form.

Sinus bradycardia

Sinus bradycardia is characterized by a regular but slow sinus rhythm (less than 65 beats per minute).

Extrasystole

This type of rhythm disturbance is associated with extraordinary contractions of the entire heart muscle or some part, which is caused by a spontaneous electrical impulse from the atria or ventricles. This type of arrhythmia is a rather dangerous condition, especially when it is group, as it can develop into ventricular fibrillation or ventricular tachycardia.

Paroxysmal tachycardia

Impulse conduction disorders in paroxysmal tachycardia

Arrhythmias associated with impaired atrioventricular conduction

The second name is blockade. According to the place of origin they are divided into:

Sinoatrial block - impulses from the sinoatrial node do not enter the atria, which is typical for structural damage to the heart. Therapy is aimed at the underlying disease.
Intraatrial block is detected in heart defects, myocardial inflammation, coronary heart disease, as well as in case of poisoning of certain antiarrhythmic drugs.
Atrioventricular (AV) block is a delay in the conduction of impulses from the atrium to the ventricle. Occurs during inflammatory and destructive processes in the heart, myocardial infarction. Increased irritation of the vagus also plays a role in the occurrence of AV block;
Intraventricular blockade - occurs in the conduction system of the heart (disorders in the His bundle, blockade of the right and left legs of the bundle of His). This type of blockade does not require special therapy.
Wolff-Parkinson-White syndrome or premature ventricular depolarization. It develops when additional pathways appear. More often affects men than women. A separate syndrome does not require treatment; in some cases, when combined with paroxysmal tachycardia, β-blockers, cardiac glycosides, are prescribed.

On the ECG, these types of arrhythmia are characterized by loss of contractions of the ventricles and atria (PQRS complex), a predominance of P waves, and deformation of the ventricular complexes.

Atrial fibrillation

The ECG is characterized by two characteristic changes: the absence of the P wave (the atria are not excited, instead there are atrial waves), and a different interval between the QRS complex.

Ventricular fibrillation

This type of arrhythmia is a very severe pathology that accompanies terminal conditions. The causes of fibrillation are myocardial infarction, electric shock, and drug poisoning. When this pathology occurs, minutes count and emergency electrical defibrillation is necessary. With the development of this arrhythmia, a person loses consciousness, turns sharply pale, the pulse in the carotid arteries disappears, and the pupils dilate. This occurs due to the cessation of effective blood circulation, i.e. means it stops.

The ECG is displayed as a wave of one amplitude, on which it is impossible to distinguish complexes and waves, the rhythm frequency is 250-300 beats per minute. There is no clear isoline.

The mechanism of occurrence of this disease

Classifications of atrial dysfunction

Research methods and their description

Exercise tests

Bicycle ergometry

Treadmill test

Tilt test

Event monitoring

ECG

Holter ECG

Electrophysiological study

Useful video

Conclusion

Heart Abilities

What does atrial fibrillation look like on an ECG?

Sinus arrhythmia

Extrasystole

First signs

How is an ECG taken?

Teeth, leads, intervals

ECG analysis

Ventricular fibrillation

The most disappointing diagnosis: heart attack

Cardiogram of the heart

Parasystole of the heart

Treatment

Holter method

Bicycle and ECG

What is phonocardiography?

Educational elements.

Common causes of rhythm disturbances

Arrhythmias caused by a failure in the formation of an electrical impulse

Sinus arrhythmia

Sinus tachycardia

Sinus bradycardia

Extrasystole

Paroxysmal tachycardia

Arrhythmias associated with impaired atrioventricular conduction

Atrial fibrillation

Ventricular fibrillation

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