Sinoauricular blockade 2nd degree treatment. Sinoatrial blockades. You are one of the millions who have a heart condition

Sinoatrial blockade is a process of slowing the conduction of electrical impulses through the heart muscle. It is quite rare. Pathology is detected at any age. It develops twice as often in men as in women.

Clinically manifested by discomfort in the heart area; a severe form of blockade can lead to cardiac arrest. The disease is subject to mandatory treatment.

The essence of pathology

Sinoauricular block is a type of sick sinus syndrome. With this pathology, the conduction of impulses from the atrial node, located in the atrial appendage, to the myocardium is disrupted. Electrical impulses are either slowed down or blocked completely.

As a result, atrial contractions are disrupted. This causes the entire heart to contract out of sync as the ventricles continue to pump at their normal rhythm. Hemodynamic disturbance occurs.

Causes

Sinoauricular block occurs due to:

• lesions of the sinus node;
• myocardial compaction;
• increasing the function of the vagus nerve.

The causes of these conditions are:

• congenital and acquired heart defects;
• ischemic disease - myocardial infarction with subsequent hardening of muscle tissue;
• acute or chronic inflammation of the myocardium;
• congenital or acquired cardiomyopathy;
• intoxication with certain medications and chemicals.

Thus, the disease occurs due to a disruption in the formation of an electrical impulse or a slowdown in its conduction through muscle tissue.

Sinoauricular block in children develops after the age of seven, when autonomic dysfunction develops. In most cases, this condition goes away on its own. If signs of the disease appear before this age, the child should be examined to identify a congenital defect.

Degrees of blockade

Depending on the severity of impulse conduction disturbances, three degrees of sinoauricular block are distinguished. The greater the degree, the more severe the symptoms observed.

Table. Degrees of sinoatrial block.

Degree	Impulse conduction	Clinical manifestations	Signs on ECG
First	Impulses occur less frequently than in a healthy person, but all reach the atrium myocardium	Does not manifest itself, can only be detected on an ECG	Decrease in heart rate, calculated by increasing the R-R interval
Second	Some of the generated impulses do not reach the atrial myocardium	Discomfort in the heart area, shortness of breath on exertion, dizziness	Periodicals by Samoilov-Wenckebach appear. This is the loss of the P wave, indicating contraction of the atrium, and the ventricular complex
Third	Impulses are either not produced or their conduction is completely blocked	Feeling of heart sinking, dizziness and tinnitus. With the development of asystole - sudden loss of consciousness, complete cardiac arrest, death	There are no P waves, only ventricular contraction or asystole is observed.

The second degree of blockade is divided into two types:

• in the first type, there is a gradual increase in the interval between contraction of the atrium and ventricle;
• with the second type, the pause between contractions is always the same.

Chronic sinoatrial blockade of the 3rd degree leads to the development of heart failure and cerebrovascular accidents, which manifests itself:

• sudden fainting;
• the appearance of swelling in the legs;
• enlarged liver;
• pale skin;
• constant shortness of breath.

Also, the 3rd degree of blockade is characterized by Morgagni-Adams-Stokes attacks - a sudden decrease in heart rate to less than 40 per minute. In this case, loss of consciousness occurs, muscle cramps, involuntary urination and defecation develop.

Transient blockade in childhood does not have specific manifestations, as it is caused by increased work of the vagus nerve. If a child develops symptoms such as pale skin and discomfort in the heart area, increased fatigue is a reason to contact a pediatric cardiologist.

To diagnose the disease, electrocardiographic examination and daily monitoring of heart function are used. The examination is mandatory for conscripts. If there is a 2nd or 3rd degree blockade, exemption from the army is given.

Treatment

Therapeutic measures differ for each degree of the disease. For first-degree blockade, no special treatment is required. The underlying disease is corrected and the patient is systematically monitored. It is recommended to normalize the work and rest regime, give up bad habits, and adhere to the principles of a healthy diet.

If the cause of the block is dysfunction of the vagus nerve, symptomatic treatment is prescribed:

• wearing loose clothing;
• adequate physical activity;
• walks in the open air;
• treatment of diseases of the stomach and intestines;
• psychotherapy.

More active therapy is prescribed for second and third degree blockades. Drug treatment is not always effective. To increase the heart rate, the following drugs are used:

• Atropine;
• Nifedipine;
• Cardiket;
• belladonna preparations.

The effect of their use is short-term and unstable. The following drugs are contraindicated in patients with established sinoatrial block:

• cardiac glycosides;
• beta blockers;
• potassium preparations.

To improve myocardial conductivity, metabolic drugs are used - riboxin, ATP, cocarboxylase. Vitamin therapy courses are carried out periodically

With the development of a Morgagni-Adams-Stokes attack, cardiopulmonary resuscitation measures are indicated.

If signs of hemodynamic and cerebral circulation disturbances appear, surgical treatment is indicated. It is carried out by implanting an artificial pacemaker. Indications for surgical intervention:

• persistent bradycardia with corresponding symptoms;
• taking blockade-provoking drugs for health reasons;
• constant fainting;
• signs of heart failure.

A pacemaker is placed temporarily or for life. To prevent blockade attacks, it is recommended to normalize your lifestyle, give up bad habits, and try to avoid stress. Patients are monitored at the dispensary and undergo regular examinations.

Conclusion

Sinoatrial blockade is a slowdown in the conduction of electrical impulses due to disruption of the atrial node or pathology of the heart muscle. As a result, asynchronous contraction of the atria and ventricles is observed. Depending on the severity of the blockade, it is asymptomatic or leads to the development of severe circulatory disorders until it stops. Drug treatment is ineffective; surgery is generally indicated - implantation of an artificial pacemaker.

Description:

Sinoauricular (sinoatrial) blockade is a type in which the conduction of an electrical impulse between the sinoatrial node and the atria is blocked. With sinoauricular block, there is a temporary atrium and loss of one or more ventricular complexes. Sinoauricular block is relatively rare in cardiology. According to statistics, this conduction disorder develops more often in men (65%) than in women (35%). Sinoauricular block can be detected at any age.

Causes of sinoauricular block:

Sinoauricular block can develop after, in the acute period of myocardial infarction (in 1% of cases), more often with infarction of the posterior wall (I. Markulyak, 1975).

Sinoauricular blockade may be associated with intoxication with cardiac glycosides, quinidine, potassium preparations, and beta-blockers. More often it is recorded when the atrial myocardium is damaged, especially near the sinus node, by a sclerotic, inflammatory or dystrophic process. Sometimes it occurs after defibrillation, very rarely - in practically healthy individuals with increased tone of the vagus nerve.

Sinoauricular blockade is possible at any age. According to statistics from K. Rasmusen (1971), it is observed more often in men (65%) than in women (35%).

The mechanism of sinoauricular blockade has not yet been elucidated. The question has not been resolved as to what is the cause of the blockade - a decrease in atrial excitability “or suppression of the impulse in the node itself. According to D. Scherf (1969), the permanent form of blockade is associated with organic changes in the sinus node. In recent years, sinoauricular block is increasingly considered as sick sinus syndrome.

Classification:

There are sinoauricular blockades of I, II and III degrees.
Sinoauricular block of the first degree is not detected on a regular electrocardiogram. In this case, all impulses generated by the sinus node reach the atria, but they originate less frequently than normal. Persistent sinus block may indirectly indicate sinoauricular block of the first degree.
With sinoauricular block of the second degree, some impulses do not reach the atria and ventricles, which is accompanied by the appearance of Samoilov-Wenckebach periods on the ECG - loss of the P wave and the associated QRST complex. In case of loss of one cardiac cycle, the increased R-R interval is equal to two main R-R intervals; if more cardiac cycles occur, the pause may be 3 R-R, 4 R-R. Sometimes the conduction of every second impulse following one normal contraction is blocked (sinoauricular block 2:1) - in this case they talk about allorhythmia.
In contrast to stage II atrioventricular block, in which only the QRS complex is lost, with sinoauricular block there is loss of the atrial and ventricular complexes.
With sinoauricular block of the third degree, there is a complete blockade of impulse transmission from the sinus node, which can cause asystole and death of the patient. In some cases, the role of pacemaker is assumed by the atrioventricular node, the conduction system of the atria or ventricles.

Symptoms of sinoauricular block:

There are no clinical manifestations of sinoauricular block of the first degree. Auscultation can determine the absence of another heart contraction after 2-3 normal cycles.
The symptoms of second degree sinoauricular block depend on the frequency of sinus impulse loss. With rare loss of heartbeat, there is a feeling of discomfort behind the sternum and general weakness.
The absence of several cycles of heart contractions in a row, as well as sinoauricular block of the third degree, is accompanied by a feeling of cardiac arrest, tinnitus, and severe bradycardia. In the case of sinoauricular block caused by organic damage to the myocardium, congestion develops.
Against the background of attacks of asystole, patients with sinoauricular block develop Morgagni-Edams-Stokes syndrome, characterized by sudden dizziness, pale skin, flashing “spots” before the eyes, ringing in the ears, loss of consciousness, and convulsions.

Diagnostics:

Sinoauricular block should be distinguished from sinus bradycardia, sinus bradycardia, blocked atrial extrasystoles, and second degree atrioventricular block.

Sinoauricular block and sinus bradycardia can be differentiated using an atropine or exercise test. In patients with sinoauricular block, during these tests the heart rate doubles and then suddenly decreases by 2 times (blockade occurs). With sinus bradycardia, the rhythm gradually increases.

An extended pause with sinoauricular block is not associated with the act of breathing, but with sinus arrhythmia it is.

With a blocked atrial extrasystole, the ECG shows an isolated P wave, while with sinoauricular block there is no P wave and the associated QRST complex (i.e., the entire cardiac cycle is missing). Difficulties arise when the P wave merges with the T wave preceding the extended pause.

With atrioventricular block of the second degree, in contrast to sinoauricular block, the P wave is constantly recorded, an increasing increase in time or a fixed time of the P-Q interval is noted, followed by a blocked P wave.

Treatment of sinoauricular block:

For sinoauricular block of the first degree, no special therapy is performed. Sometimes restoration of conductivity is facilitated by treatment of the underlying disease or withdrawal of drugs that contribute to the disorder.
With functional sinoauricular blockade caused by vagotonia, good results are achieved by using atropine orally or subcutaneously. Stimulation of the automatism of the sinus node is facilitated by the administration of sympathomimetics (ephedrine, alupent, isadrine). To improve myocardial metabolism, cocarboxylase, riboxin, and ATP are indicated.
With sinoauricular blockade, the use of cardiac glycosides, beta-blockers, antiarrhythmic drugs of the quinidine series, potassium salts, cordarone, and rauwolfia preparations is contraindicated.
In the event that sinoauricular blockade significantly worsens the patient’s well-being or is accompanied by attacks of asystole, temporary or permanent electrical stimulation of the atria (implantation of a pacemaker) is resorted to.

Forecast:

The development of events during sinoauricular block is largely determined by the course of the underlying disease, the degree of conduction disturbance, and the presence of other rhythm disturbances. Asymptomatic sinoauricular block does not cause severe hemodynamic disturbances; the development of Morgagni-Adams-Stokes syndrome is regarded as prognostically unfavorable.

Second degree atrioventricular (AV) block

Second-degree atrioventricular (AV) block is characterized by disruption, delay, or interruption of impulse transmission through the AV node, with the exception of the block. associated with premature atrial contraction. AV blockades can be permanent or temporary, depending on the characteristics of anatomical or functional disorders in the conduction system. which are divided into type I block, or Mobitz type I and Wenckebach block - Mobitz block type II, 2:1 block and complete AV block.

Differential diagnosis of type I and type II second-degree AV block is based on electrocardiographic data, and not on the anatomical location of the block site. Type I is characterized by a progressive increase in impulse latency. Type II is characterized by episodic or periodically recurring sudden blockade of impulse conduction without a prior noticeable increase in conduction time. Accurate localization of the site of blockage within the conduction system is critical for proper treatment of individuals. having second degree AV block.

Of course, 2:1 AV block cannot be classified as type I or II, since only one PR interval is used for diagnosis. Both 2:1 blocks and blocks involving two or more sinus P waves are sometimes called complete AV block, in which some conduction is observed at the sites of the block, unlike third-degree AV block.

Pathophysiology

Type I AV block most often results from conduction disturbances in the AV node, but in rare cases may be associated with infranodal block and is rarely secondary to structural abnormalities of the AV node. when the QRS complex is narrow and there is no underlying heart disease. In such cases, type I AV block may be vaginally mediated and may be observed in conditions involving relatively high parasympathetic tone, such as in highly trained athletes, overdose of cardiac glycosides (eg, digoxin), and neurogenic (or neurotransmitter) syncope syndrome.

Vagal-mediated AV block occurs in the node when, under the influence of parasimatic influences, a slowdown in sinus rhythm is observed on the ECG. Vaginally mediated AV block improves physical performance and is observed more often during sleep, when parasympathetic tone dominates. If increased sympathetic tone (eg, exercise) initiates or worsens type I AV block, infranodal block may be suspected.

Cardioactive medications are another common cause of AV block. They may have a negative (i.e., dromotropic) effect on the AV node directly, indirectly through the autonomic nervous system, or a combination of both. Digoxin, beta blockers, calcium channel blockers, and some antiarrhythmic drugs have been reported to cause second-degree AV block.

Various inflammatory, infiltrative, metabolic, endocrine disorders and systemic collagenoses with vascular damage are accompanied by blockade of the AV node. Less commonly, type I block may be associated with conduction disturbances localized in the His bundle and its distal sections. In this situation, the QRS complex may be wide, and the baseline PR interval preceding the block is usually shorter, with reduced amplitude. The prognosis for type I infranodal block is significantly worse than for blockade at the level of the AV node. The location of the focus of type II block is most often infranodal, which determines an increased risk for the patient.

US prevalence

Almost 3% of patients with underlying structural heart disease develop some form of second-degree AV block.

Mortality/morbidity

The location of the blockade and its root cause determine the prognosis. Nodal AV blocks and the vast majority of type I blocks have a favorable prognosis, while infranodal blocks of both types can progress to complete block with a significantly worse prognosis. However, the symptoms of type I blockade can be very wide.

• Type I AV node block often has a nonprogressive course and is benign in terms of mortality. The risk of progression to complete heart block is significant when the block is localized in the His-Purkinje system (infranodal location).
• Type II AV block often progresses to third degree block and thus has a more alarming prognosis. Type II block can lead to Stokes-Adams syncope.
• Vaginally mediated AV block is generally benign in terms of mortality. but can lead to dizziness and fainting.

Sex specificity

• The number of men and women among patients with AV block is the same.

Clinical manifestations

Symptoms associated with type I block vary widely, from asymptomatic in well-trained athletes and individuals without significant structural changes in the heart, to recurrent syncope, presyncope, and bradycardia in patients with heart disease. AV block can cause cardiac arrest and angina.

Causes

Second-degree AV block can occur in the presence or absence of structural heart disease.

• Increased vagal tone may be due to pain, mechanical stress on the carotid sinus, or carotid hypersensitivity, which may result in slow sinus rhythm and/or AV block. Thus, vaginally mediated AV block can be confirmed by a slow sinus rhythm noted on the ECG. High vagal tone can be observed in athletes and young people at rest. Mobitz block type I has been described in 2-10% of observed long-distance runners.1
• Cardioactive medications are another important cause of AV block. They can have a negative effect on the AV node directly, indirectly through the autonomic nervous system, or as a result of a combination of both. Digoxin, beta blockers, calcium channel blockers, and some antiarrhythmic drugs have been implicated as causes of second-degree AV block. Some antiarrhythmic drugs can cause second-degree AV block, including sodium channel blockers such as procainamide, which are more common with distal blocks in the His-Purkinje system. Persistent AV block has been reported following adenosine infusion during a stress test in patients taking cardioactive medications, suggesting an underlying conduction disorder in addition to drug effects as the etiology of the block. Toxic levels of some other pharmacological agents, such as tricyclic antidepressants and lithium salts, may be accompanied by AV blockade. Presynaptic alpha agonists and adrenergic agents (eg, clonidine) can also cause or worsen AV block.
• Various inflammatory, infiltrative, metabolic, endocrine diseases and systemic collagenoses with vascular damage leading to blockade of the AV node are represented by the following:
• Inflammatory diseases:

• Endocarditis
• Myocarditis
• Lyme disease
• Acute rheumatic fever (ARF, rheumatism, Sokolsky-Buyo disease)

• Infiltrative diseases:

• Amyloidosis
• Hemochromatosis
• Sarcoidosis, and impaired AV conduction may be the first sign of sarcoidosis.3
• Infiltrative malignancies such as Hodgkin's lymphoma, other lymphomas and multiple myeloma 4

• Metabolic and endocrine disorders

• Hyperkalemia
• Hypermagnesemia
• Addison's disease
• Hyperthyroidism
• Myxedema
• Thyrotoxic periodic paralysis 5

• Collagenoses with vascular damage

• Ankylosing spondylitis
• Dermatomyositis
• Rheumatoid arthritis
• Scleroderma
• lupus erythematosus
• Reiter's syndrome
• Mixed connective tissue diseases (MCTD) 6

• Other diseases accompanied by AV blockades

• Heart tumors
• Injuries (including those associated with catheterization, especially with a pre-existing left bundle branch block)
• Muscular “bridges” of the myocardium 7
• Transcoronary alcohol ablation of the interventricular septum for obstructive hypertrophic cardiomyopathy
• Transcatheter occlusion of atrial or ventricular septal defect 8, 9
• Heart surgery for congenital malformations, especially near the septum
• Progressive (age-related) idiopathic fibrosis of the cardiac skeleton
• Valvular complications of cardiovascular disease, especially aortic stenosis and aortic valve replacement
• Obstructive sleep apnea associated with a range of cardiac arrhythmias, including AV block.10
• Muscular dystrophies. The development of defects in patients with muscular dystrophy is progressive, therefore, these patients should undergo careful clinical evaluation and follow-up, even if they have a benign conduction defect, such as first-degree AV block.11
• Acute myocardial infarction (MI) can lead to second-degree AV block.
• In some patients, AV block may have autosomal dominant features and tend to be inherited. Several mutations in the SCN5A gene have been associated with hereditary AV blocks. Various mutations in another gene have been reported in other dysrhythmias, such as long QT syndrome or Brugada syndrome.

Sinoatrial block is a pathological condition that is accompanied by a disturbance in the natural heart rhythm. Parts of the myocardium contract asynchronously, resulting in temporary asystole. Naturally, such a violation is dangerous. Many patients are looking for more information about this pathology. Why does the blockade develop? Are there any external symptoms? What treatment methods does modern medicine offer? The answers to these questions will be of interest to many readers.

What is sinoatrial block?

In order to explain the essence of the pathology, you first need to pay attention to the anatomical and physiological features of the human myocardium. As you know, the heart is a partially autonomous organ. Its reduction is ensured by the work of special cells that conduct nerve impulses.

An important part of the heart rate drivers is the sinus node. It is located between the right atrial appendage and the opening in the wall of the right atrium. The sinoatrial junction has several branches, including the bundle of Thorel, Bachmann, Wenckebach - they conduct impulses to the walls of both atria. Disruption of normal conduction in this area is called sinoatrial node block.

Thus, against the background of pathology, malfunctions occur, which leads to asystole, which, of course, is extremely dangerous. It is worth saying that this is a rather rare pathology - it is diagnosed in 0.16% of patients in the cardiology department. And according to statistical studies, men over fifty years of age most often suffer from the disorder. In female representatives, such a deviation is observed less frequently.

It is possible for the blockade to develop in childhood, but this usually occurs against the background of congenital organic lesions of the myocardium.

The main causes of pathology

It is worth understanding that SA blockade is not an independent disease. This is rather a sign of other pathologies. Almost 60% of patients with blockade suffer from coronary heart disease. In addition, pathology often occurs against the background of or after myocardial infarction.

In addition, there are other reasons that can lead to disruption of normal heart rhythm. Risk factors include viral and bacterial myocarditis, as well as calcification of the heart muscle and congenital forms of cardiomegaly. Sometimes SA blockade develops in people suffering from rheumatism.

Blockade of the sinoatrial node can be caused by taking too large doses of cardiac glycosides, beta blockers, quinidines and some other medications. Excess potassium in the blood often leads to the development of pathology. Since the work of the heart is regulated by the vagus nerve, an increase in its tone can also lead to rhythm disturbances (a strong blow or injury to the chest, some reflex tests that increase the activity of nerve endings).

Causes include other ailments, including heart valve defects, the presence of a tumor in the brain, malfunction of the thyroid gland, severe hypertension, meningitis, encephalitis, leukemia, and pathologies of cerebral vessels. As you can see, there are a huge number of risk factors.

First degree blockade and its features

In modern medicine, it is customary to distinguish three degrees of severity of this pathology. Each of them has its own characteristics. The mildest form is considered to be first-degree sinoatrial block. With such a pathology, each impulse that occurs in the area of ​​the sinus node reaches the atria. But it happens with some delay.

This pathology cannot be seen on an electrocardiogram, and there are no external manifestations - patients for the most part feel normal. The first degree of blockade can be diagnosed by performing intracardiac EPI.

Second degree blockade: brief description

This stage of pathology development is usually divided into two types:

• A 2nd degree block of the first type is accompanied by a gradual decrease in conductivity in the area of ​​the sinus node. Such a disorder can already be diagnosed on an ECG. As for external symptoms, patients often complain of periodic dizziness and weakness. As the disease develops, short-term loss of consciousness, provoked by increased physical exertion, severe coughing, sudden turns of the head, etc., becomes a frequent occurrence in a person’s life.
• A 2nd degree blockade of the second type is already accompanied by clear disturbances in heart rhythm, which the patient himself can feel. For example, the heartbeat first increases (a person can feel contractions), then abruptly stops, and after a pause it resumes. During periods of asystole, the patient feels severe weakness and often loses consciousness.

What signs are accompanied by a 3rd degree blockade?

Third degree pathology is a complete sinoatrial block. In this case, the myocardium does not receive impulses from the sinus node at all. Naturally, the pathology is visible on the ECG, because against the background of a complete block of conduction, the patient develops asystole. In this case, an elusive ectopic rhythm appears due to the activity of third-order drivers. During electrocardiography, you can notice that the PQRST complexes are absent.

Drug treatment

It’s worth saying right away that the treatment regimen largely depends on the cause of the pathology. If the sinoatrial block is partial and is not a threat to the patient’s life, then specific therapy may not be required at all - the heart rhythm may normalize on its own.

However, the primary disease must be treated. For example, if the blockade is provoked by an increase in the tone of the vagus nerve, then it is important to administer Atropine to the patient (can be replaced with Ephedrine, Orciprepalin, Isoprenaline). In the event that heart rhythm disturbances occur due to an overdose, taking potentially dangerous medications should be stopped immediately and an attempt should be made to remove the remaining medications from the body.

Unfortunately, quite often such rhythm disturbances lead to the development of fibrotic changes in the myocardium. In such cases, it is possible to ensure normal contraction of the heart muscle only through constant electrical stimulation.

First aid for blockade

As already mentioned, in most cases the blockade is partial and is not a direct threat to the patient’s life. However, in some cases, complete cessation of the transmission of electrical impulses leads to sudden cardiac arrest.

If there is a serious disturbance in the heart rhythm, even to the point of stopping, atrial stimulation is performed. As a short-term measure, you can press on the eyeballs (helps change the heart rate). Unfortunately, sometimes the patient requires cardiac massage and connection to a life support machine.

All human organs and systems are interconnected. Violation of the functions of one organ immediately affects others. However, there are organs that, even if they stop working, do not pose a real threat to human health and life, since their functions are taken over by others. And there are those that, at the slightest disruption, significantly disrupt human life.

The heart is an irreplaceable organ. Moreover, any violation of its functions affects every cell of the body. Many diseases can disrupt its activity. One of them is sinoatrial block, also called sinoauricular or SA block. What do these concepts mean, what danger does this disease pose, what causes contribute to its development, and can it be cured?

general description

To understand what sinoatrial A-blockade is, you need to understand the anatomical features of the heart muscle. As you know, the heart is a pumping mechanism that pumps blood through the contraction of the heart chambers - the atria and ventricles. At the same time, the contractions themselves become possible thanks to electrical impulses formed in the sinoatrial or sinus node.

This component of the heart is one of the pacemakers, which is located in the right atrium. And it consists of several branches, which include the Thorel, Bachmann and Wenckebach bundle. These branches carry electrical impulses to both atria. Sinoatrial block is a condition in which the conduction of impulses is disrupted.

Sinoatrial block, as a rule, occurs against the background of other cardiac pathologies, as a result of which scars and other obstacles are formed in the heart muscle, interfering with the conduction of the impulse. As a result, a person develops arrhythmia, which leads to asystole. Asystole is a dangerous condition in which the heart stops as a result of the disappearance of electrical activity.

It should be noted that sinoatrial blockade accounts for no more than 0.16% of all heart diseases. That is, the disease is quite rare, and it is most often diagnosed in men who have crossed the 50-year mark.

However, SA blockade is also diagnosed in children. However, in childhood, disturbances in the conduction of electrical impulses are usually caused by congenital heart diseases.

Reasons for the development of SA blockade

Among the main causes of impulse conduction disturbances, the following can be noted:

• damage to the sinus node;
• violation of impulse propagation throughout the myocardium;
• change in the tone of the vagus nerve.

In some cases, the disease occurs because the impulse is not formed at all, or it is so weak that myocardial cells, called cardiomyocytes, are unable to recognize it, or they are insensitive to it. It is not uncommon for an impulse to encounter obstacles in the form of scars through which it cannot pass.

There are many factors that can provoke the development of sinoatrial block. These include the following pathologies:

• heart defects, both congenital and acquired;
• inflammatory processes in the myocardium;
• systemic connective tissue diseases;
• damage to heart tissue due to cancer or injury;
• coronary heart disease, developing against the background of cardiosclerosis, or as a consequence of myocardial infarction;
• myocardial infarction, which causes death of a section of the heart muscle;
• cardiomyopathy;
• some types of VSD;
• intoxication of the body caused by an overdose of certain medications or intolerance to them, as well as poisoning by various chemicals.

The functions of the sinus node are directly influenced by the vagus nerve. Sinoatrial blockade can occur when its activity changes. However, in this case, as a rule, it does not pose a serious threat to human life, since it can pass without medical intervention.

Types of SA blockade and symptoms

Based on the severity of the arrhythmia, sinoatrial blockade is divided into several degrees:

• 1st degree;
• 2nd degree;
• 3rd degree.

SA blockade 1st degree

In this case, we speak of incomplete SA blockade, when the sinus node functions uninterruptedly, and the impulses cause myocardial contractions in the atria. However, with this pathology, the heart muscle receives impulses somewhat less frequently than necessary. In this case, sick people do not feel any manifestations of the disease, and no changes are recorded during an ECG.

The presence of 1st degree SA blockade can be suspected based on a single sign – bradycardia. And it can only be diagnosed with an electrophysiological study of the heart.

SA blockade 2nd degree

A distinctive feature of 2nd degree sinoatrial block is that the formation of impulses does not always occur. As a result, in some cases there are no myocardial contractions, which is recorded on the ECG.

This pathology is divided into two types:

• SA blockade of the second degree, type 1;
• SA blockade of the second degree, type 2.

In the first case, impulse conduction decreases gradually. In this case, the patient is concerned about the following symptoms:

• dizziness;
• general weakness;
• pre-fainting states;
• short-term loss of consciousness.

Loss of consciousness can be provoked by any physical activity, as well as by turning the head or coughing.

In the second case, a persistent disturbance in heart rhythm occurs, accompanied by pauses, during which sick people feel weak and often lose consciousness.

SA blockade 3rd degree

This pathology poses the greatest danger, since the flow of impulses from the sinus node stops, which means that myocardial contraction does not occur. Sinoatrial block of the 3rd degree is very often accompanied by loss of consciousness, requiring resuscitation measures.

Signs of SA blockade in children

In children, pathology can be suspected based on signs similar to those in adults. Most often, the reason for contacting a doctor is the child’s rapid fatigue and fainting, accompanied by a blue discoloration of the nasolabial triangle.

Sinoauricular block on ECG

Electrocardiography of the heart is the main method to help diagnose disturbances in the conduction of electrical impulses. However, its implementation is not effective in the case of 1st degree sinoauricular block. The only signs of pathology in this case are bradycardia, to which the person adapts, and a shortening of the PQ interval.

With 2 degrees of pathology, the following deviations are recorded on the ECG:

• the P-P indicator decreases, indicating a lengthening of the interval between atrial contractions;
• after pauses there is a gradual reduction in the time of the P-P indicator;
• one of the next PQRST complexes may be absent;
• during pauses, impulses come from other pacemakers;
• if several contractions occur, the duration of the pause is several P-P indicators.

With stage 3 pathology, an isoline is recorded on the ECG, indicating the absence of electrical impulses and myocardial contractions. During this period, the likelihood of death increases many times over.

Diagnosis of the disease

The main methods for diagnosing electrical conduction disorders of the heart are the following studies:

• Holter ECG.

Holter ECG is effective if traditional electrocardiographic examination of the heart did not detect any changes. Holter monitoring is carried out for 3 days, which makes it possible to reliably assess disturbances in the functioning of the sinus node. This type of study is also indicated for children.

Another diagnostic method is the atropine test. We can talk about the presence of pathology if, after administering this substance, the patient’s pulse first increases and then sharply decreases, which will be indirect evidence of a blockade.

Ultrasound examination of the heart helps to find the cause of the malfunction of the sinus node. This type of study allows you to detect defects, scars and other pathological changes in the structure of the myocardium.

Treatment of the disease

Sinoatrial blockade of the 1st degree does not require special therapy. In most cases, treatment of the disease that caused its disturbance helps normalize the heart rhythm. If the malfunction of the sinus node was caused by taking any medications, they are canceled.

If the cause of the disease is a change in the activity of the vagus nerve, patients are prescribed drugs based on atropine. The same drugs are also prescribed to children with VSD that has caused myocardial conduction disturbances.

Nitroglycerin, Atropine, Platiphylline and Nidefilin help relieve severe attacks of arrhythmia. However, drug therapy in this case brings only temporary relief. In particularly severe cases, patients are advised to have a pacemaker installed.

All patients, regardless of the severity of the disease, are prescribed drugs that improve metabolic processes in the myocardium and its contractility.

In addition to taking medications, children are advised to reduce their loads, reduce the intensity of sports activities, and in some cases, refuse to attend child care facilities altogether. However, if the arrhythmia is transient and there is no risk to life, it is not recommended to isolate children. In this case, you just need to regularly visit your doctor and undergo the necessary tests.