Treatment of 3rd degree AV block. Congenital or acquired atrioventricular block: degrees of disease development, treatment. Common indicators of occurrence

Transient 2nd degree AV block, if Holter monitoring reveals delays (pauses) in the conduction of an electrical impulse (signal) lasting more than 3 seconds, even if the disease is asymptomatic, is an indication for implantation of a pacemaker. Transient AV block of the 2nd stage, if delays longer than 3 seconds are not detected, require observation by a cardiologist (arrhythmologist) with periodic daily ECG monitoring. If the disease progresses, a decision will be made to install a pacemaker.

Transient 2nd degree AV block, accompanied by syncope (fainting caused by a temporary interruption of blood flow to the brain), is considered life-threatening and requires the installation of an artificial cardiac pacemaker (APM) - a pacemaker. Transient AV block, stage 2. otherwise called transient - it can be complete or partial, but, in general, it tends to progress with age.

Can transient 2nd degree AV block resolve?

In some cases, 2nd degree AV block is considered normal for young people during sleep and may resolve (or not recur) on its own. However, there are clear criteria when installing a pacemaker is required: with sinus rhythm for the atria, with a delay of more than 3 s, with atrial fibrillation - more than 5 s.

Do they take into the army with a transient 2nd degree AV block?

They definitely don’t take you to serve in the army if you have an ECS, but with a transient 2nd degree AV block they can take you, because The blockade is not permanent. In this case, we are usually talking about a staff position. If you have permanent fainting, you will not be accepted into the army.

Transient 2nd degree AV block with Wenckebach periodicity means Mobitz type I - it, as a rule, being the first or second degree, does not require special treatment, but requires observation by a cardiologist. For 2nd degree AV block type Mobitz II, permanent pacing is indicated.

Treatment of transient 2nd degree blockades

Treatment of transient 2nd degree AV block is carried out only by implantation of an electrical pacemaker. Atropine can be used while waiting for the pacemaker to be installed, but medications are not used as an independent treatment. Atropine is ineffective for complete AV block because does not affect conduction in the His–Purkinje bundle.

Treatment for transient 2nd degree AV block of type 1 is often not required - it occurs during sleep even in healthy people, but the disease is classified as unfavorable and, if diagnosed, requires observation by a specialist.

Ensuring blood supply to the vessels at the time of the cardiac impulse is necessary to supply oxygen to the internal organs. Blockade of impulses transmitting contractions can lead to persistent heart failure and more serious consequences.

How does AV block manifest?

Atrioventricular block of 1-3 degrees on the ECG immediately marks a decrease in ventricular contractions (bradycardia). The coordinated work of the conductive fibers of the myocardium conducts rhythmic impulses generated by the sinus node and propagating along the atrial fibers to the AV node, from which they pass further through the ventricular tissue.

At each of the 4 levels, blocking of impulses can occur, which, depending on the location of the obstacle, is called atrioventricular sinoatrial, intraatrial, and intraventricular block.

Intraatrial does not pose any particular danger, sinoatrial is accompanied by bradycardia and a rare pulse, atrioventricular can, to a certain extent, cause hemodynamic disturbances.

According to statistical data, AV block, in the form of a transient phenomenon, can also occur in relatively healthy people, but as a percentage, cases of its manifestation are much more common in those who already have various cardiac disorders. According to WHO, in 17% of cases of atrioventricular block, an unfavorable scenario occurs, leading to death.

Atrioventricular block is one of the existing types of cardiac dysfunction, which is often caused by the presence of another cardiac pathology. Impaired conduction from the atria to the ventricles causes disruption of the heart rhythm and disruption of vascular patency. This can lead to impaired hemostasis.

Classification and types of existing violations

In modern domestic medicine, V. Doshchitsin’s classification is used for functional diagnostics, which provides for a typological differentiation of existing functional failures at certain levels. Changes in electrocardiographic parameters and pronounced clinical symptoms can be observed in the His bundle, in the atrial tract or in the atrioventricular node.

Based on the location of the functional failure, reflected on the ECG, there are three proximal and one distal - a total of 4 types of atrioventricular blockades:

• in the atrial tract;
• stem;
• in the bundle of His;
• three-bundle (trifascicular).

The leading position in the cause-and-effect series is occupied by the atrioventricular node, which is due to its specific structure. Following the sinus node, which provides the heart rhythm, it acts as a pacemaker if the higher one fails. Special heart cells, consisting of actin and myosin, are concentrated in the lower part of the right atrium, near the septum, and can conduct electrical impulses or excite spontaneously.

The work of two cell channels, slow and fast, ensures the smooth functioning of the heart. To understand the importance of the functional activity of the node, it should be added that it is through the right coronary artery that 90% of all nutrition is delivered to the cells.

According to time duration, AV blockades are divided into:

• short-term and permanent;
• random and periodic.

Another gradation is formed according to the degree of pulse passage:

• when incomplete, the majority of impulses still reach the ventricle;
• at full conductivity there is no conduction at all.

The characteristic according to the degree of severity is the main one that is generally accepted, and implies a division according to symptoms, duration and nature of the electrocardiographic indicators. The parameters of the conduction of cardiac impulses and the degree of development of the disease provide grounds for dividing the typological varieties into 1, 2, 3 degrees of severity. In this case, the third means complete atrioventricular block.

Degrees of atrioventricular blockade

The degrees of AV are determined by the clinical picture and ECG readings. First degree atrioventricular block does not require treatment and is characterized by a slight delay in the conduction of electrical impulses. It can only be detected during an electrocardiographic study, but sometimes this condition is diagnosed in young and healthy people, and even athletes.

If 1st degree atrioventricular block is detected, the prescription of drugs that reduce the heart rate is limited or prohibited. Detection of the 1st degree becomes a signal for a more vigilant attitude towards health, and forces a medical search for the causes, the consequence of which is a violation of the conduction of heart impulses.

Atrioventricular block of the 2nd degree is diagnosed with a partial disruption of impulse conduction, which is usually sudden in nature and is accompanied by severe negative symptoms.

Due to an unstable state, a person may experience weakness, darkening of the eyes, even loss of consciousness, which occurs due to the failure of impulses to pass through.

During the period when the presence of the second degree can be diagnosed, events develop according to two scenarios. The first is a gradual progression of the duration of non-passage; in the second scenario, the impulses do not pass suddenly, and every second or third one no longer reaches its destination.

Atrioventricular block of the 3rd degree is characterized by a sharp slowing of the pulse, fainting and darkening of the eyes, severe cyanosis of soft tissues, convulsions and pain in the heart. This condition occurs when atrioventricular patency is completely disrupted, and the heart ventricles contract under the influence of their own, but slower, rhythm.

Complete atrioventricular block, which usually results in death, is especially often diagnosed in elderly patients who previously suffered from chronic cardiac pathologies.

Diagnosis of pathology

The basis for stating the presence of a pathological condition, diagnostic evidence of the development of a certain period, is usually an ECG with signs of AV block, which shows conduction and rhythm disturbances, accompanied by well-studied and described symptoms. Interpretation of the ECG becomes a compelling basis for confirming diagnostic assumptions.

ECG signs of atrioventricular block can be observed in varying degrees of severity, and this is associated with both the severity and the level of blocking of the motivating impulse. Clinical symptoms include:

• unequal impulse frequency of the atria and ventricles;
• pulse waves that occur at the moment of random coincidence of systole;
• periodic loud tone upon auscultation of the heart.

ECG signs and their significance in diagnosis

For all types of 1st degree AV block, be it internodal, nodal, trunk, three-fascicular, or combined, it is characteristic that the PQ interval (the time interval from the beginning of the P wave to the beginning of the Q wave) increases with both bradycardia and tachycardia, but sinus rhythm correct.

In the nodal proximal P waves are normal, in the atrium they are often split, in the distal one the width of the P wave does not exceed 0.11 s.

With type 2 blockades, the sinus rhythm is no longer correct, and individual excitation impulses are blocked as they pass from the atria to the ventricles. The nodular form, also known as Mobitz type 1, is characterized by:

• loss of the ventricular QRST complex, but the P wave is preserved, and the PQ interval is only slightly widened;
• 2nd degree AV block of type 2:1, with preserved sinus rhythm, implies loss of every second QRST complex;
• with progressive type 2 atrioventricular block, two or even more QRST complexes fall out in a row, while the P wave is preserved.

With any type of 3rd degree AV block, the ventricular rhythm is maintained, but the atrial and ventricular rhythms are completely separated.

In the proximal form, with complete atrioventricular dissociation, the QRS complex is practically unchanged, but about 60 or less ventricular contractions are observed. The distal form is accompanied by a smaller number of ventricular contractions, and widening and deformation of the QRS complex.

Atrioventricular block can be combined with fibrillation or atrial flutter (Frederick's syndrome), or Morgagni-Adams-Stokes syndrome (hemodynamic disturbances and hypoxia of internal organs). Such a syndromic complex leads to an attack that can be fatal.

Impaired blood hemodynamics and cardiac arrhythmia in the 2nd and 3rd degree of AV block are usually a consequence of existing heart diseases, and, if repeated regularly, can lead to irreversible consequences or death.

Causes of pathology

Modern cardiology conventionally divides the causes of heart block into:

• organic;
• functional.

Organic include pathologies of the cardiovascular system, chemical (medicinal) effects on the impulse-conducting bundles, or myocardium, and surgical interventions in the heart area. Functional ones can be multiple in nature and refer to any disorders of the body (including the central nervous system, which lead to pathology in the natural processes of impulse transmission in the human body). About 1 in 20 thousand newborns also have congenital heart defects that can cause similar disorders.

Sclerotic or fibrous lesions in the myocardial fibers, which form in numerous diseases, are the most common cause of AV, and manifest a special type of blockade, known as cardiomyopathic.

Among these etiological reasons, we can list:

• cardiopathy of autoimmune, diphtheria, or thyrotoxic origin;
• rheumatoid diseases with accompanying cardiac complications;
• myocarditis;
• collagenoses;
• sclerotization of the heart vessels;
• some systemic diseases;
• infectious chronic lesions (syphilis).

Uncharacteristic reasons include stupid:

• chest injury;
• progressive muscular dystrophy;
• water-electrolyte imbalance;
• hemosiderosis;
• hemochromatosis.

However, clinical practice shows that atrioventricular block is becoming increasingly widespread, resulting from the use of medications - calcium channel blockers, beta blockers, cardiac glycosides, and some groups of cardiac and muscle stimulants. In this case, the cause of the blockade can be an overdose or prolonged use of the drug.

It has been noted that severe hypothermia, cardiac catheterization, and an attack of angina pectoris or coronary heart disease can cause a severe degree of blockade. In old age, a short-term one can be triggered by hiccups, swallowing, severe coughing, and even sudden physical effort.

Symptoms of pathology

The symptom complex can develop according to a negative scenario of varying severity, depending on the patient’s age, concomitant cardiac lesions, and the general physical condition of the body.

Weakness and shortness of breath, a feeling of flushing and instant heat, increased fatigue, and dizziness - all this can be a concomitant symptom complex to stage 1 of atrioventricular block, which does not require treatment, but requires the immediate adoption of preventive measures.

Impaired cardiac function of this type can lead to stages of the disease that involve negative consequences. Timely consultation with a cardiologist will help you avoid serious health problems.

Diseases of the heart and blood vessels are now especially common among the population of different ages. Such diseases pose a serious threat to health and even life, and are provoked by a variety of factors, including congenital predisposition, unhealthy lifestyle, and the pathological influences of other diseases. One of the fairly common ailments of the cardiovascular system is considered to be atrioventricular block, which can vary in severity. In short, this condition is simply called AV block. We will consider the disease of 1st, 2nd and 3rd degrees in more detail, and also discuss its treatment and talk about how prevention is carried out.

About what kind of AV block there is (degree of condition)

AV block is a form of blockade of the conduction of natural electrical impulses through the atrioventricular node, located between the atria and ventricles. There are three degrees of this pathological condition, depending on whether the electrical impulse is conducted slowly, periodically, or completely blocked.

With first-degree AV block, each impulse from the atria reaches the ventricles, but its conduction is delayed literally for a split second - at the moment it passes through the atrioventricular node. This pathological condition does not make itself felt in any way. It occurs in well-trained athletes, as well as in adolescents and young adults who have high vagus nerve activity. In addition, 1st degree AV block can occur against the background of rheumatism, heart damage, sarcoidosis, etc.

2nd degree AV block is manifested by the fact that not every impulse reaches the ventricles from the atria. In this case, a rare and often irregular contraction of the heart is observed. Sometimes such a blockade transforms over time into a 3rd degree blockade.

With 3rd degree AV block, the conduction of natural impulses from the atria to the ventricles completely stops. The heart rate and rhythm of the heart are set by the atrioventricular node or directly by the ventricles. The lack of natural stimulation by the sinus node leads to the fact that ventricular contractions occur very rarely - less than forty times per minute. Thus, 3rd degree AV block is a dangerous arrhythmia that can negatively affect the pumping function of the heart. The patient experiences fainting, dizziness and heart failure. If the ventricles contract more than forty times per minute, the symptoms are less serious, but patients suffer from fatigue, hypotension (during elevation of the body), and shortness of breath.

About how AV block is corrected (treatment)

If a patient has 1st degree AV block, which is not accompanied by negative symptoms, only dynamic observation is indicated. If the disorder is caused by the consumption of medications, for example, cardiac glycosides, drugs against arrhythmia or beta blockers, it is important to adjust their dosage or completely stop them.

Second-degree AV block requires treatment of the disease, and third-degree disease is a reason for serious monitoring and long-term therapy.

If AV blockades are of cardiac origin (developed against the background of a heart attack, myocarditis, cardiosclerosis, etc.), the patient is prescribed therapy with beta-adrenergic stimulants, for example, isoprenaline or orciprenaline. Over time, a pacemaker is implanted.

First aid medications (if necessary to stop Morgagni-Adams-Stokes attacks) are isadrine or atropine. The first is administered sublingually, and the second - subcutaneously. To correct the phenomena of congestive heart failure, diuretics are used, as well as cardiac glycosides (only with caution) or vasodilators. For symptomatic treatment, medications such as teopeca, belloid and corinfar are usually used.

A radical method of treating AV blockade is the installation of a so-called pacemaker. This type of surgery helps restore normal rhythm and heart rate. The decision about surgical correction is made after consultation with a cardiac surgeon.

How to prevent AV block (prevention)

The main measure for preventing AV block is systematic observation by a cardiologist, especially in old age. Such observation involves, first of all, taking an ECG - an electrocardiogram, as well as monitoring the heart rate in case of any suspicion of any violations. Prevention of AV block also involves maintaining a healthy lifestyle, giving up bad habits, as well as proper nutrition, rich in potassium and magnesium.

Additional Information

The prognosis for patients with AV block depends on the degree of the disorder, as well as the type of underlying disease. The most serious prognosis is typical for patients with 3rd degree AV block. Such patients are disabled and develop heart failure.

At the same time, early implantation of a special pacemaker makes it possible to increase the life expectancy of patients with this diagnosis by an order of magnitude, as well as significantly improve their quality of life. Also, timely implantation helps prevent the worsening of the degree of AV block.

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P.S. The text uses some forms characteristic of oral speech.

It is found in 0.5% of young people without signs of heart disease. In the elderly, 1st degree AV block is most often the result of an isolated disease of the conduction system (Lenegra's disease).

With 2nd degree AV block, some of the atrial impulses do not reach the ventricles. The block can develop at the level of the AV node and the His-Purkinje system.

2nd degree AV block with 3:1 conduction.

• If during AV block (for example, with 4:3 or 3:2 conduction) the PQ intervals are unequal and Wenckebach periodicity is observed, they speak of 2nd degree AV block of the Mobitz type I.

• In second-degree AV block, Mobitz type I, the QRS complexes are usually narrow because the block occurs above the His bundle at the level of the AV node.

• Even if bundle branch block is present in Mobitz type I AV block, the level of AV block is most likely at the level of the AV node. However, in this case, a His bundle electrogram is necessary to confirm the level of blockade.

Advanced AV block (3:1, 4:1 and higher) refers to 2nd degree AV block of the Mobitz type II. In this case, the QRS complexes are usually wide (characteristic of right or left bundle branch block), and the level of the block is located below the AV node. Mobitz type II AV block usually occurs at or below the level of the His-Purkinje system. It often progresses to complete AV block.

Third degree AV block, or complete AV block, can be acquired or congenital.

total systemic lupus erythematosus.

Clinical picture

First degree AV block is usually asymptomatic.

• As the PQ I interval lengthens, the heart sound becomes quieter, therefore, for 1st degree AV block a quiet I tone is characteristic; for 2nd degree AV block of the Mobitz type I, the volume of the I tone decreases from cycle to cycle, and for complete AV block she is different all the time.

• With complete AV block, a functional mesosystolic murmur may occur.

Etiology

The causes of AV block are given in the table. The most common cause is isolated disease of the conduction system (Lenegre's disease). In addition, AV block can occur during myocardial infarction, usually in the first 24 hours. It occurs in patients with inferior myocardial infarction and in 2% of patients with anterior infarction.

• Digoxin
• Beta blockers
• Some calcium antagonists
• Antiarrhythmic drugs with quinidine-like action

• Congenital complete AV block (often with systemic lupus erythematosus in the mother)
• Atrial septal defect of the ostium primum type
• Transposition of the great arteries

• Infective endocarditis
• Myocarditis (Chagas disease, Lyme disease, rheumatism, tuberculosis, measles, mumps)

• Primary adrenal insufficiency

• Carotid sinus syndrome
• Vasovagal reactions

Diagnostics

1st degree AV block

This diagnosis is made when the PQ interval is more than 0.20 s in adults and more than 0.18 s in children. Each P wave is followed by a QRS complex, the shape of the P wave and QRS complex is normal.

2nd degree AV block

2nd degree AV block type Mobitz I is placed if the following symptoms are present:

• The PQ interval gradually lengthens, and then after the next P wave the QRS complex drops out.

• The PQ interval gradually lengthens, but with each cycle by an ever smaller amount, so that the RR interval becomes shorter from cycle to cycle until the next ventricular complex falls out.

• The pause at the end of the Wenckebach period is shorter than any two consecutive RR intervals.

• The PQ interval after the pause is less than the PQ interval before the pause.

• QRS complexes form groups called Wenckebach periods.

2nd degree AV block Mobitz type II is less common than Mobitz I. It is characterized by the following symptoms:

• The PQ interval is the same all the time, but some atrial impulses are not conducted. In this case, unlike blocked atrial extrasystoles, the PP interval is constant.

• With advanced AV block, there is more than one P wave per QRS complex (this is called AV block with conduction 3:1, 4:1, etc.). The QRS complexes are often wide (in contrast to Mobitz type I block, which is characterized by narrow complexes).

Complete AV block

AV dissociation is characteristic, that is, a complete absence of temporal relationship between P waves and QRS complexes. The P waves can be used to calculate the atrial rate.

Treatment

For 1st degree and 2nd degree Mobitz type I AV block, no treatment is required. For 2nd degree Mobitz type II AV block and complete AV block, permanent pacemaker is usually indicated.

• Atropine can reduce AV block if it is due to increased parasympathetic tone, but not ischemia.

• Atropine is more effective for AV block against the background of inferior than against the background of anterior myocardial infarction.

• Atropine does not affect conduction in the His-Purkinje system and is therefore ineffective in complete AV block, as well as in 2nd degree AV block caused by blockade at the level of the His-Purkinje system.

• Atropine has no effect on the transplanted heart.

• In 2nd degree Mobitz type II AV block, atropine should be used with caution as it may decrease the ventricular rate. Thus, a 2:1 AV block at an atrial rate of 80 beats per minute may progress to a 3:1 AV block at an atrial rate of 90 beats per minute, causing the ventricular rate to drop from 40 to 30 beats per minute.

Antidigoxin (Fab fragments of antibodies to digoxin) is used for hemodynamically significant AV block caused by digoxin. The dose is calculated as follows:

Number of vials = Weight (kg) × Serum concentration of digoxin (ng/ml) ⁄ 100

Complete AV block in inferior myocardial infarction is often transient, so a temporary pacemaker is usually sufficient.

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2nd degree atrioventricular block - 2nd degree AV block

Atrioventricular block of the 2nd degree is characterized by a slowdown in conduction in the projection of the AV node and in nearby areas of the conduction system of the heart.

Incomplete AV block of the second degree is of three types.

1. Atrioventricular block of the 2nd degree I Mobitz is accompanied by a gradual lengthening of the P-Q (R) interval with subsequent loss of the ventricular QRST complex (the so-called Samoilov-Wenckebach periodicity) and a stable, preserved P wave.
2. In the case of anterograde atrioventricular block of the second degree (Mobitz type II), the P wave is recorded on the electrocardiogram and the ventricular Q-T complex falls out without a gradual increase in the P-Q (R) interval, which remains normal or extended.
3. Second degree AV block of type 2:1, 3:1. On the ECG, every second (2:1) two or more QRST complexes in a row (3:1 blockade, etc.) are lost, which leads to severe bradycardia and the development of syncope states. Severe ventricular bradycardia contributes to the formation of replacement contractions and rhythms.

Principles of treatment for patients with 2nd degree AV block:

1. In patients with first-time atrioventricular block of the 2nd degree, it is necessary to carry out therapy for the underlying disease, which in some cases leads to the disappearance of cardiac conduction disturbances;
2. It is necessary to discontinue all antiarrhythmic drugs and other drugs that slow down AV conduction;
3. It is necessary to prescribe drugs that increase heart rate, improve AV conduction and reduce the negative effect of the parasympathetic nervous system on the sinus node and atrioventricular conduction, atropine, belladonna derivatives - belloid, belospon, sympathomimetics, and the like. Atropine can reduce AV block only when parasympathetic nerve (vagal) activity is increased, but not during ischemia. Atropine sulfate is more effective in 2nd degree AV block in lower than in anterior myocardial infarction in people. Atropine is practically ineffective in the development of complete AV block, and in Mobitz II degree AV block, atropine must be used cautiously, due to the fact that it may even reduce the frequency of ventricular contraction. Atropine sulfate has no effect on the transplanted heart. Of the sympathomimetic group of drugs, preference is most often given to isoproterenol (isadrin), which is available in 5 mg tablets. Isadrin is used sublingually or as an infusion (at a dose of 0.5 to 5-7 mcg per 1 minute) or intramuscular injection. Glucocorticosteroids are used for myocarditis (they have an anti-inflammatory effect), but they are not effective for ischemic heart disease. Saluretics, which remove potassium and thereby improve AV conduction, are indicated only for hyperkalemia;
4. A pacemaker is implanted for 2nd degree AV block of type II Mobitz and III degree, accompanied by syncopal attacks of Morgagni-Adams-Stokes syndrome;
5. If Morgagni-Adams-Stokes syndrome occurs, emergency care is provided in full.

In people suffering from myocardial infarction in the acute period, the duration of complete AV block depends on the size and location of the heart muscle necrosis and in most cases it goes away on its own. Implantation of a permanent pacemaker is carried out 1 month after the onset of the disease. In case of heart disease, implantation of a pacemaker can eliminate syncope, but this does not reduce the risk of sudden cardiac death.

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What is AV block: causes, diagnosis and treatment

From this article you will learn: what AV block is, how treatment and prognosis depend on the severity, what is the life expectancy after implantation of a pacemaker, how to support the heart at home.

Atrioventricular block is the cessation of nerve impulse transmission between the atria and ventricles of the heart.

This is what happens with the most severe atrioventricular block (3rd degree)

The harmonious functioning of the heart is coordinated by the autonomic conduction system of the heart. It consists of special muscle fibers that are capable of conducting nerve impulses. The “leader” of the autonomic conduction system of the heart is the autonomic nervous system.

The peculiarity of the conduction system of the heart is that its fibers are able to independently generate the impulse necessary for contraction. In this case, the number of impulses decreases from top to bottom.

The conduction system of the heart is called autonomous because it itself produces impulses for myocardial contraction. This gives a person a margin of safety for survival. In case of severe injuries, loss of consciousness and other disasters, the heart continues to beat, increasing the chances of life.

Normally, the sinus node generates a rhythm with a frequency of 60 to 90 beats per minute. The atria contract at this rate. The task of the atrioventricular part is to delay the excitation wave on its way to the ventricles. Contraction of the ventricles begins only after the atria have completed their work. The frequency from the atrioventricular part is 40–60 pulses. This is not enough for a full life, but still better than nothing.

The atrioventricular node is part of the conduction system of the heart

A condition in which the impulse is not conducted from the sinus node is called AV block. The lower its level, the fewer impulses the heart receives. A decrease in heart rate makes blood circulation ineffective and, in severe cases, threatens life.

A cardiologist treats heart blocks. It should be contacted if a person feels interruptions. After 40 years, it is advisable to consult a cardiologist annually in order to “catch” the problem at an early stage. Initial forms of blockades respond well to treatment, and you can live with them for many years. In the case of moderate blockades, they can be compensated for by regular medication use and proper alternation of exercise and rest. Severe cases are treated by implantation of a pacemaker, with which one can successfully live to an old age.

Why does this blockade occur?

There are several main reasons:

There are a lot of diseases that cause AV block. Rheumatic heart disease, amyloidosis, Addison's disease, thyrotoxicosis, collagenosis and other conditions can be distinguished. Researchers claim that the likelihood of heart block is inherited: mutations of the genes responsible for conducting the impulse are being actively studied.

Regardless of the cause, atrioventricular block can vary in severity. Mild diseases are treated by a cardiologist; in more complex cases, the participation of a cardiac surgeon is required.

Three degrees of severity

There are 3 degrees of severity: the first is the mildest, and the third is called complete or transverse heart block. The second degree is also divided into 3 subtypes. The degree of severity is determined by a combination of clinical signs and ECG results.

Electrocardiographic signs of AV blocks of varying degrees are as follows:

Blockades of 2 and 3 degrees develop in two cases: with high tone of the parasympathetic nervous system (has inhibitory functions) and with diseases accompanied by inflammation, infiltration, endocrine and metabolic disorders. The tone of the parasympathetic part of the autonomic nervous system increases with heavy sports loads and overdose of vasoactive drugs.

Characteristic symptoms

Atrioventricular block manifests itself differently depending on the severity.

1st degree

The first degree may not be clinically detected. This is an incidental finding in young people under 20 years of age, its frequency in the world is just over 1%. It reduces tolerance to heavy physical activity. Athletes are more susceptible to it; their frequency reaches almost 9%. With age, the number of people suffering from such a blockade increases to 5%.

This problem is found in almost all people suffering from myocarditis and severe infections. With recovery from the infection, the blockade also passes.

2nd degree

Manifestations of 2nd degree AV block are noticeable from the moment heart rhythm disturbances begin.

• When the heart rate decreases, the minute volume, or the number of liters of blood that the ventricles can pump, decreases.
• Initial manifestations are shortness of breath during exercise, vague chest pain, and weakness.
• With a decrease in the frequency of beats, the patient feels interruptions, as if the heart freezes for a while.
• Dizziness, darkening of the eyes, and brief fainting may occur.
• Weakness, headaches, and shortness of breath increase.

These symptoms may be intermittent; a person does not see a doctor for a long time, attributing it to ordinary fatigue. The frequency of these blockades is up to 3% of the entire population in any country.

3rd degree

Atrioventricular block of the 3rd degree (or complete transverse) is life-threatening. All organs suffer from oxygen starvation and metabolic disorders.

The most striking symptom is Morgagni-Adams-Stokes, or fainting, which developed due to cerebral ischemia. 3 or 10 seconds after the blockade occurs with a heart rate of up to 40 beats per minute, the person suddenly turns pale, loses consciousness and falls. Usually after 1–2 minutes the blood flow is restored, the person comes to his senses and gets up, his skin turns red at this time. Needless to say, how dangerous this symptom is in an urban environment or while driving. If blood flow does not return on its own, immediate life-saving medical measures are required.

Differences in heart rate with different types of atrioventricular block

Diagnostics

Today, atrioventricular block is no longer a death sentence. First of all, the cardiologist prescribes an examination to find out all the details of the body’s condition. It includes Holter monitoring, ultrasound of the heart chambers, and laboratory tests.

Holter monitoring is a 24-hour recording of an ECG using a recorder or recorder that is attached to the patient’s body. Continuous recording can be maintained for several days. At the same time, the patient records all his actions in time: got up, walked, climbs the stairs, eats, communicates, and so on. By comparing activity activity and the ECG tape, the cardiologist gets an objective picture.

Treatment methods

1st degree

1st degree blockade does not require treatment unless it is caused by inflammation. Patients with endo- or myocarditis are treated in a cardiology hospital. The criterion for recovery is the disappearance of blockade on the ECG, restoration of normal sinus rhythm.

2nd degree

Second degree blockade of the second and third types is an indication for immediate hospitalization. Restoring rhythm is an urgent task. The doctor’s goal is to facilitate the passage of impulses from the atria to the ventricles; with AV blockade at the level of the atrioventricular node, atropine is used for this, but at a lower location the medicine will not help.

If a conduction interruption is recorded at the level of the left bundle branch or even lower, then electrical stimulation is needed. It is possible to restore normal rhythm using electrical stimulation; for this purpose, temporary stimulation is used when a probe electrode is inserted into the right atrium. This is a preparatory stage for the installation of a permanent pacemaker.

3rd degree

Complete transverse block is life-threatening and is treated in the intensive care unit. If the condition is caused by organic damage to the heart (infarction, Lenegra syndrome or idiopathic bilateral damage to the His bundle, cardiosclerosis), then adrenergic agonists are first used - orciprenaline or isoprenaline. Then the general condition of the person is assessed, whether his body can cope with a heart attack or adapt to cardiosclerosis. If adaptation does not occur and the rhythm does not hold, then a pacemaker is installed.

An artificial pacemaker is also called a pacemaker. The operation to install it is a minor one and is performed under local anesthesia. An active electrode under X-ray control will be inserted through the lateral saphenous vein of the arm into the right atrium, and a small titanium housing will be placed under the subcutaneous fat on the chest, usually on the left.

The pacemaker housing is placed under the subcutaneous fat of the chest. To ensure that it is not rejected by the body, it is made of titanium (or a special alloy), which is inert for our body

Forecast

Various AV blocks are the fourth most common cause of heart rhythm disturbances. On average, the prognosis for these conditions looks like this:

Patients with a pacemaker should avoid exposure to radar installations and high-voltage equipment. They cannot undergo MRI examinations or receive thermal physical therapy. You can return to normal life in a month and a half. Pacemakers are replaced within 5 to 15 years; this is their average service life.

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Atrioventricular block (AV) of the heart: causes, degrees, symptoms, diagnosis, treatment

Normally, the human heart beats at a rate of beats per minute. This rhythm sufficiently ensures blood supply to the vessels at the time of heart contraction in order to fully meet the oxygen needs of the internal organs.

The normal conduction of electrical signals is due to the coordinated work of the conducting fibers of the myocardium. Rhythmic electrical impulses are generated in the sinus node, then travel along the atrial fibers to the atrioventricular junction (AV node) and further along the ventricular tissue (see image on the left).

A block to conduction of an impulse can occur at each of the four levels. Therefore, sinoatrial, intraatrial, atrioventricular and intraventricular blockades are distinguished. Intraatrial blockade does not pose a danger to the body; sinoatrial blockade can be a manifestation of sick sinus syndrome and be accompanied by severe bradycardia (rare pulse). Atrioventricular (AV, AV) blockade, in turn, can lead to severe hemodynamic disturbances if conduction disturbances in the corresponding node of 2 and 3 degrees are detected.

Statistical data

According to WHO statistics, the prevalence of AV block based on the results of daily ECG monitoring reaches the following figures:

• In healthy young people, 1st degree blockade is recorded in up to 2% of all subjects,
• In young people with functional or organic pathology of the heart and blood vessels, 1st degree blockade is recorded in 5% of all cases,
• In persons over 60 years of age with underlying heart pathology, 1st, 2nd and 3rd degree AV block occurs in 15% of cases,
• In persons over 70 years of age - in 40% of cases,
• In patients with myocardial infarction, 1st, 2nd or 3rd degree AV block is recorded in more than 13% of cases,
• Iatrogenic (drug) AV block occurs in 3% of all patients,
• Atrioventricular block is the cause of sudden cardiac death in 17% of all cases.

Causes

1st degree AV block can occur normally in healthy people if there is no underlying myocardial damage. In most cases it is transient (transitory). This type of blockade often does not cause clinical manifestations, and therefore is detected during a routine ECG during preventive medical examinations.

Also, grade 1 can be found in patients with a hypotonic type of vegetative-vascular dystonia, when parasympathetic influences on the heart predominate. However, persistent 1st degree blockade may indicate a more serious heart pathology.

Grades 2 and 3 in the vast majority of cases indicate the presence of organic myocardial damage in the patient. These diseases include the following (according to the frequency of blockade detection):

1. Cardiac ischemia. Due to the fact that during ischemia the myocardium experiences a prolonged, chronic lack of oxygen (hypoxia), the performance of the heart muscle decreases sharply. Microscopic foci of tissue appear that do not contract fully and do not conduct impulses. If such foci are located on the border of the atria and ventricles, then obstacles arise in the path of the impulse, and a blockade develops.
2. Acute and subacute myocardial infarction. The mechanism of the blockade is similar, only the cause of the disruption of impulse conduction is both foci of ischemic tissue and necrotic (dead) myocardial tissue.
3. Congenital and acquired heart defects. The mechanism for the development of blockade is a gross violation of the morphological structure of muscle fibers, since heart defects lead to the formation of cardiomyopathy -

structural changes in the chambers of the heart.

Symptoms

Symptoms of 1st degree AV block may be scanty or absent altogether. However, patients often note such signs as increased fatigue, general weakness, a feeling of shortness of breath during physical activity, dizziness and a feeling of interruptions in the heart, pre-syncope with flickering spots before the eyes, ringing in the ears and other harbingers of what is now the person will lose consciousness. This is especially pronounced when walking or running quickly, since a blocked heart is unable to provide adequate blood flow to the brain and muscles.

2nd and 3rd degree AV block is much more pronounced. During a rare heartbeat (less than 50 per minute), the patient may lose consciousness for a short period of time (no more than 2 minutes). This is called an attack of MES (Morgagni-Edams-Stokes) and is life-threatening, since this type of conduction disorder can lead to complete cardiac arrest. But usually the patient regains consciousness, bypass and additional conduction pathways “turn on” in the myocardium, and the heart begins to contract at a normal or slightly lower frequency. However, a patient with an attack of MES must be promptly examined by a doctor and hospitalized in the cardiology, arrhythmology or therapeutic department of the hospital, since the issue of the need to install a pacemaker, or artificial pacemaker, will subsequently be decided.

In extremely rare cases, a patient may never regain consciousness after an attack of MES, in which case he should be taken to the hospital as quickly as possible.

Diagnosis of AV block

The algorithm for diagnosing rhythm disturbances in general and AV block consists of the following measures:

If the patient has the above-described complaints, call an emergency medical team or be examined by a therapist (cardiologist/arrhythmologist) at a clinic at the place of residence with an electrocardiogram.

The ECG will immediately show signs such as a decrease in the parameter reflecting ventricular contractions (bradycardia), an increase in the distance on the film between the P waves responsible for atrial contractions and the QRS complexes responsible for ventricular contractions. In case of 2nd degree AV block, Mobitz type 1 and Mobitz type 2 are distinguished, which are manifested on the ECG by periodic loss of ventricular contractions. With grade 3, an extremely rare pulse appears due to a complete transverse block, the atria work in their normal rhythm, and the ventricles in their own (with a frequency of a minute or less).

After the patient is hospitalized in the department of therapy, cardiology or arrhythmology, he undergoes instrumental methods of further examination:

• Ultrasound of the heart (echocardioscopy), to clarify the nature of myocardial pathology, if any; the contractility of muscle tissue and the ejection fraction of blood into large vessels are also assessed,
• Holter monitoring of blood pressure and ECG during the day with subsequent assessment of the degree of blockade, the frequency of its occurrence and its relationship with physical activity,
• Exercise testing is used in patients with myocardial ischemia and chronic heart failure.

In any case, only a doctor can prescribe an exact examination plan for a patient during an in-person examination.

Treatment of AV block

Patients with 1st degree atrioventricular block do not require treatment if they do not have organic heart pathology or diseases of other organs.

In mild cases, it is usually enough to make lifestyle adjustments - give up fatty fried foods, eat right, spend more time in the fresh air and eliminate bad habits. In the presence of vegetative-vascular dystonia, contrast showers have a beneficial effect on the cardiovascular system.

If the patient notices weakness, fatigue and decreased activity, accompanied by low blood pressure and a rare pulse (at least 55 per minute), he can take courses of tinctures of ginseng, schisandra or eleutherococcus as general strengthening and tonic drugs, but only in consultation with the attending physician .

With 2nd and 3rd degree AV block, especially accompanied by attacks or MES equivalents, the patient requires full treatment.

Thus, treatment of the underlying disease of the heart or other organs comes to the fore. While the underlying cause of the block is being diagnosed and the first steps are being taken to treat the block, the patient is prescribed drugs such as atropine, isadrine, glucagon and prednisolone (subcutaneously, in tablets or intravenously, depending on the drug). In addition, it is possible to prescribe teopek, aminophylline or corinfar (nifedipine, cordaflex) in tablets.

As a rule, after treatment of the underlying disease, conduction through the AV node is restored. However, a formed scar in the area of ​​the node can cause persistent conduction disturbance in this place, and then the effectiveness of conservative therapy becomes questionable. In such cases, it is preferable for the patient to install an artificial pacemaker, which will stimulate contractions of the atria and ventricles at a physiological frequency, providing the correct rhythmic pulse.

The operation to install an pacemaker can currently be performed free of charge according to quotas obtained from the regional departments of the Ministry of Health.

Are there possible complications of AV block?

Complications from atrioventricular block can indeed develop, and they are quite severe and life-threatening. For example, an attack of MES due to a pronounced rare pulse with complete AV block can lead to sudden cardiac death or arrhythmogenic shock. In addition to acute complications, in patients with long-term AV block, the course of chronic heart failure is aggravated, and discirculatory encephalopathy develops due to constantly reduced blood flow through the vessels of the brain.

Prevention of complications includes not only measures initially aimed at the occurrence of severe cardiovascular pathology. Timely consultation with a doctor, complete diagnosis and competent treatment will help to identify the blockade in time and avoid the development of complications.

Disease prognosis

Prognostically, 1st degree AV block is more favorable than 2nd and 3rd degrees. However, in the case of correctly selected therapy for grades 2 and 3, the risk of complications is reduced, and the quality of life and its duration in patients improves. An installed pacemaker, according to a number of studies, significantly increases patient survival in the first ten years.

Heart blocks prevent normal blood flow to organs, causing changes in their function. They can occur in children and adults. Different types of blockades pose varying degrees of danger to the body.

In some cases, patients do not suspect that they have a heart pathology, considering themselves practically healthy.

Their heart block is detected during a physical examination or an ECG when visiting a doctor with another disease. The words “heart block”, discovered by the patient in the ECG report, cause panic fear of complete cardiac arrest. Should they be afraid?

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Description of the pathology

In the heart muscle there are clusters of nerve cells (the so-called nodes), in which nerve impulses arise, which spread along special nerve fibers throughout the myocardium of the atria and ventricles of the heart and cause their contractions.

One of these nodes (sinoatrial) is located in the atrium. It is here that an electrical impulse arises, which, spreading further into the atrioventricular node, ensures a normal heart rhythm. These nodes are called cardiac pacemakers.

The fibers through which impulses are transmitted from pacemakers to muscle fibers are called the conduction system. From the atrioventricular node to the muscles of the ventricles of the heart, impulses pass through bundles of nerve fibers called the bundle branches (left and right).

Impaired propagation of impulses generated in the atrial pacemaker is called heart block. They can be transmitted slowly or their conduction along the nerve fibers completely stops - partial or complete heart block develops accordingly. In any case, such changes cause cardiac arrhythmias.

With a slow rate of impulse passage, a longer than normal pause occurs between the contraction of the atria and ventricles. If the impulse is not carried out at all, then contraction of the atria or ventricles of the heart does not occur (atrial or ventricular asystole).

And only the next signal to contract is effective; contractions then occur at normal intervals until the next blockade.

Impairment of the conductivity of the electrical impulse can occur at different levels, which causes various forms of blockades. In this case, blood circulation is disrupted: in the absence of contraction of the ventricles, blood is not pushed into the blood vessels, pressure drops, and organ tissues are not provided with oxygen.

1st degree heart block and its consequences

Atrioventricular heart block (AV block) is the impaired passage of nerve impulses through the fibers of the conduction system between the atria and ventricles of the heart, which causes a serious malfunction of the cardiovascular system.

The danger and significance of AV blockade depend on its severity. There are 3 degrees of blockade severity:

Causes of congenital forms of blockade in children:

• maternal diseases (diabetes mellitus, systemic lupus erythematosus);
• widespread damage to connective tissue in the mother’s body;
• abnormalities in the development of the septa between the atria or ventricles;
• underdevelopment of the conduction system in the heart.

Congenital heart block quite often causes the death of a baby in the first year of life. Clinical manifestations in newborns are:

• cyanosis of the lips, nasolabial triangle, fingertips or skin of the body;
• severe restlessness or lethargy of the child;
• breast refusal;
• increased heart rate;
• increased sweating.

In cases of acquired disease, more severe conduction disturbances develop, including complete heart block. But even the most dangerous 3rd degree AV block is not always clinically manifested by severe symptoms. Some children have only one symptom - a decrease in the number of heartbeats.

As the process progresses, the cavities of the heart gradually expand, the overall blood flow slows down, and oxygen starvation of the brain substance develops. Hypoxia is manifested by memory deterioration and decreased academic performance.

The child is lagging behind in physical development, he often complains of dizziness and gets tired quickly. Increased physical activity or stress can lead to fainting.

Diagnostics

Atrioventricular block is diagnosed using an ECG: the interval between the P wave and the QRS complex increases, although the waves themselves are normal. will be even in the absence of any complaints from patients.

If 1st degree AV block is detected at a young age, in a well-trained person, then further in-depth examination may not be carried out.

But short-term recording of an ECG at rest does not always capture single, rarely occurring blockades. If there are complaints or any objective data on the heart, the doctor prescribes daily Holter monitoring. The monitor's sensors are attached to the chest. The examined patient leads a normal, habitual lifestyle.

The device continuously records ECG throughout the day, which is then analyzed. This absolutely painless, non-invasive diagnostic method allows you to determine the frequency of blockades, their dependence on the time of day and the patient’s physical activity. The study helps, if necessary, choose the right treatment.

Echocardiography (ultrasound of the heart) may also be prescribed. This study makes it possible to examine the septum, walls and cavities of the heart, and identify pathological changes in them as a possible cause of blockages. Their root cause may be a change in the valves.

Treatment

Atrioventricular block of the 1st degree (and sometimes 2nd) does not always require treatment. Only when cardiac pathology is detected is individually selected therapy carried out, which can also affect the frequency of blockades.

1st degree heart block in a child does not require drug treatment. Such children need constant monitoring by a pediatric cardiologist with regular ECG monitoring.

If there is a complete blockade, children are prescribed anti-inflammatory drugs, nootropics, drugs with antioxidant effects, and vitamins. If the child loses consciousness, emergency assistance should be provided to the child in the form of a closed heart massage. Congenital blockades and severe forms of acquired heart block are eliminated using an implanted pacemaker.

When the 1st degree of AV blockade passes into the 2nd degree according to the 2nd type (Moritz 2), into a partial (or complete) blockade of the 3rd degree, treatment is mandatory, since such severe conduction disturbances can cause sudden death from cardiac arrest.

The main method of restoring normal heart function is to implant a permanent or temporary pacemaker (PAC) into the patient. Temporary electrical stimulation is necessary, for example, in case of acute heart block resulting from myocardial infarction.

In preparation for the installation of an pacemaker, a complete examination of the patient and drug treatment (prescription of Atropine and other drugs) are carried out. It will not relieve the patient of the disease; it is used during the period of preparation for pacemaker implantation.

Installation of pacemaker is a surgical treatment method. It can be performed under local or general anesthesia. Its essence lies in the fact that the cardiac surgeon inserts special electrodes into the heart through the vessels (starting from the subclavian vein) and fixes them. And the device itself is sewn under the skin.

The impulse generated by the device causes normal contractions of the atria and ventricles at normal intervals. Rhythmic heart function and adequate blood supply to organs are restored. Stopping blood flow and sudden fluctuations in pressure disappear.

Clinical symptoms (dizziness and loss of consciousness) disappear, which significantly reduces the risk of cardiac arrest and sudden death.

After the operation, the patient is discharged on days 2-7 (after the studies have been performed). When applying a cosmetic suture, there is no need to remove it; it gradually dissolves. Upon discharge, the heart surgeon will recommend how long physical activity should be avoided.

A follow-up examination by a cardiologist is required after 1 month. A doctor's consultation is then recommended 6 and 12 months after surgery and annually thereafter. On an individual basis, the doctor will allow (in the absence of contraindications) sports activities after a few months.

The average period of use of the pacemaker is 7-10 years. In children it is smaller, which is associated with the child’s growth. The device is programmed (heart parameters are set) individually for each patient.