Sinoatrial blockade ecg. Features of diagnosis and treatment of sinoatrial heart block

For the normal and coordinated functioning of organs and systems, a regular and sufficient supply of blood is necessary, which is ensured through heart contractions. The main function of the heart - contractility - can be disrupted by various disruptions in the conductivity of the myocardium - the heart muscle. One of these disorders is sinoatrial block, details of the causes, symptoms and treatment of which in children and adults are discussed in the article.

What is sinoatrial block and what are its causes?

The sinoatrial node (sinus node) is located in the wall of the right atrium slightly lateral to the mouth of the superior vena cava, midway between its opening and the right atrial appendage. The branches of the sinoatrial node (bundles of Bachmann, Wenckebach, Thorel) go to the myocardium of both atria and the atrioventricular junction. The disruption of the passage of the sinus impulse through the sinoatrial node is called sinoatrial block, or sinoauricular block.

Experts note that sinoatrial block is nothing more than a type of SSS (sick sinus syndrome), when the electrical impulse between the sinoatrial node and the atria is blocked. As a result, transient, temporary atrial asystole develops, which leads to loss of one or more ventricular complexes. Most often, incomplete blockade develops, in which any part of the impulses arising in the sinus node is not transmitted to the atria and ventricles. Less commonly, a loss of 2-3 cycles is observed, as a result of which a long pause is recorded during the examination, 3 times higher than normal intervals.

The disease is rare, affecting approximately 0.16% of people. It is most often diagnosed by ECG in people over 50 years of age, and about 70% of them are male. Sometimes sinoatrial blockade is observed in children, in the vast majority of cases - with congenital or acquired organic heart pathology at an early age.

The causes of blockade in 60% of cases are associated with progressive coronary heart disease, which is associated with damage to the right coronary artery, as well as with myocardial infarction of posterior localization against the background of coronary artery disease. In 20% of people, the pathology was diagnosed in connection with myocarditis of viral and bacterial etiology. Other possible causes of sinoatrial block:

rheumatism;
myocardial cardiosclerosis;
myocardial calcification;
severe hypertension;
overdose or side effect from taking drugs - beta blockers, cardiac glycosides, quinidine;
excess potassium in the blood;
hypersensitivity of the carotid sinus;
conducting reflex tests that lead to an increase in the tone of the vagus nerve;
brain tumors;
leukemia;
pathologies of cerebral vessels;
meningitis and encephalitis;
congenital cardiomegaly;
thyroid diseases;
CHD (valvular defects);
chest injury.

If the disease occurs in a child from birth, it may be hereditary, which is transmitted in an autosomal dominant manner. Also, sinoatrial blockade often develops a few days after electrical impulse therapy. Up to a third of cases of sinoauricular block remain without an identified cause of development, but if the pathology is fatal, then the autopsy shows fibrosis of the sinoauricular junction and various disorders in other parts of the conduction system of the heart. Thus, the anatomical basis of this disease is always degenerative or inflammatory processes of the sinus node and the tissues surrounding it.

Classification of pathology

Sinoatrial block occurs for various reasons, but they are all classified into the following groups according to the type of disorder:

Blocking the conduction of impulses from the sinus node to the atria.
Low impulse strength from the sinus node.
Complete absence of impulse production in the sinus node.
Poor susceptibility of the atrial myocardium to conduct electrical impulses.

Also, sinoatrial blockade is divided into the following degrees:

First degree - there is an increase in the conduction time of the impulse from the sinoatrial junction, but still this impulse reaches the atria, albeit with a delay. This disease is not visible on an ECG; it can only be determined using EFA.
Second degree - there is a periodic disturbance in the conduction of impulses to the atria, resulting in loss of ventricular complexes, which is determined by ECG. This degree of blockade is divided into two subtypes - sinoatrial blockade 2nd degree, type 1 (conduction disturbances develop gradually with periodically complete sudden disappearance of ventricular complexes) and type 2 (periods of absence of excitation of the heart muscle without a previous increase in sinoatrial conduction time).
Third degree, or complete sinoatrial block. The impulse from the sinus node does not reach the atria at all, and asystole continues until the 2nd or 3rd order pacemaker is activated.

Symptoms of manifestation

With sinoatrial blockade of the 1st degree, which is called partial (incomplete), the patient does not show any complaints, so it can only be detected after a thorough examination for other pathologies. Blockades of 2-3 degrees are more serious diseases, but the clinical picture during their development will largely depend on the rhythm frequency, the adaptation of a particular organism to a slower rhythm (bradycardia).

The second degree of sinoatrial blockade causes cerebrovascular accidents. Clinically, this manifests itself in the form of regular dizziness, sometimes leading to fainting, weakness, decreased performance, a feeling of the heart slowing down or the absence of its beating at any moment. Symptoms can develop as extrasystole, if the patient has only single impulses blocked, and also as bradycardia, if every 2nd impulse is blocked.

A more vivid clinical picture is provided by 3rd degree sinoatrial block. When the AV connection takes over the role of pacemaker, the person may not feel the heart rhythm at all. Other possible symptoms of the disease:

syncope;
unexpected, causeless failures (fainting);
frequent dizziness;
memory impairment;
signs of heart failure - shortness of breath, suffocation, attacks of cardiac asthma, swelling, enlargement of the liver.

Complications of sinoatrial blockade

Severe bradycardia, which can be caused by complete sinoatrial block when the heart rate is less than 40 beats per minute, leads to frequent and severe attacks of Morgagni-Adams-Stokes. They not only provoke unpleasant symptoms - loss of consciousness, involuntary bowel movements and urination, muscle cramps and breathing problems, but can also cause sudden death, which more often happens with prolonged fainting.

In general, the prognosis even with complete sinoatrial block is considered more favorable than with complete atrioventricular block, since death is much less common. The prognosis will depend on the cause of the pathology, the type of blockade, associated arrhythmias and the overall health of the heart. The worst outcome is for elderly people who suffer from constant partial blockade due to coronary artery disease, since it most often turns into a complete blockade and ends in cardiac arrest.

Diagnostic methods

The main diagnostic method is an ECG, although to identify the first degree of blockade you will need to undergo an electrophysiological study - EFA. ECG signs of different degrees of sinoatrial block are as follows:

Second degree blockade of type 1 - the frequency of discharges in the sinus node is constant, there is an extended P-P interval during the pause, and there is a gradual shortening of the intervals before the pause.
Blockade of the 2nd degree, type 2 - a pause equal to the P-P interval, doubled or tripled, periodic loss of the PQRST complex is observed.
Blockade of the 3rd degree (complete) - absence of PQRST complexes (asystole), registration of the isoline until the next order pacemaker is activated. This manifests itself as the appearance of an ectopic rhythm with the absence of a normal P wave. Atrial fibrillation is often present.

For a more detailed study of heart function and diagnosing sinoatrial blockade, many patients are recommended to have 24-hour ECG monitoring, as well as a transesophageal ECG (the latter is required to detect complete blockade). To clarify the cause of the pathology, an ultrasound of the heart and other examinations are most often performed as indicated. Differential diagnosis is made with sinus arrhythmia, atrial extrasystole, sinus bradycardia.

Treatment methods

When the disease is caused by short-term causes, for example, an overdose of cardiac glycosides, sinoatrial blockade can be completely eliminated. It may go away without treatment once the influence of the risk factor ceases. With the development of sinoatrial blockade against the background of increased tone of the vagus nerve, which often happens in young people, the administration of Atropine, as well as sympathomimetics - Isoprenaline, Orciprenaline, helps. In some cases, drug therapy brings only short-term results, but an unstable improvement in rhythm, even in such a situation, can be achieved with the help of nitrates (Cardiket, Olycard), anticholinergics (Platifillin), as well as Nifedipine, Bellaspon, Belloid, Nonachlazine. However, all of these medications are not tolerated by many patients and contribute to the development of ectopic arrhythmias, so they should be used only with great caution.

Pacemaker implantation is mandatory for those patients who have repeated attacks of syncope (Morgagni-Adams-Stokes attacks), severe symptoms, as well as episodes of clinical death and increasing signs of heart failure. When the causes of the pathology cannot be corrected, then permanent pacemaker is performed (for example, cardiosclerosis, cardiac fibrosis in old age). Myocardial infarction, acute myocarditis, and severe drug overdose require temporary cardiac pacing. Only an ECS will solve the problem of complete sinoatrial block, which causes conduction failures, tachyarrhythmias and threatens sudden cardiac arrest. Read about the differential diagnosis of myocarditis

What not to do

With sinoatrial blockade, you should not overload yourself with heavy work, practice competitive sports and static loads, eat with an abundance of salt and animal fats, not get enough sleep, expose yourself to prolonged stress, or lead an unhealthy lifestyle.

Preventive measures

It is not possible to prevent the hereditary form of the disease. Cases of sinoatrial blockade acquired during life can be prevented with early correction and treatment of cardiac diseases and the exclusion of inappropriate medications and their overdoses. You should regularly visit a cardiologist if you have coronary artery disease and lead a healthy lifestyle to prevent myocardial infarction. Monitoring hormonal levels, the state of the thyroid gland, blood vessels, and preventing chest injuries are important tasks for the patient, which can also be classified as measures of nonspecific prevention of sinoatrial blocks.

Are you one of the millions who have heart disease?

Have all your attempts to cure hypertension been unsuccessful?

Have you already thought about radical measures? This is understandable, because a strong heart is an indicator of health and a reason for pride. In addition, this is at least human longevity. And the fact that a person protected from cardiovascular diseases looks younger is an axiom that does not require proof.

The materials presented are general information and cannot replace medical advice.

Sinoatrial (SA) block

Sinoatrial block II degree type I with Wenkenbach periodicity

Second degree SA block of type II (Mobitz block) is characterized by loss of the sinus complex without changes in the P-P intervals (Fig. 48). This type of block occurs in long pauses as a result of sudden blocking of one or more sinus impulses without preceding periodicity. Despite the absence of changes in the P-P intervals in the conducting complexes, a certain ratio can be established between the total number of sinus impulses and the number of impulses conducted to the atria - 2:1, 3:1, 3:2, 4:3, etc. Sometimes the loss can be sporadic. The extended P-P interval is equal to double or triple the main P-P interval. If the pause is prolonged, replacement complexes and rhythms arise. Regular 2:1 SA block mimics sinus bradycardia. If the cessation of conduction in the SA junction is prolonged to values of 4:1, 5:1 (the pause is a multiple of the duration of 4-5 normal cycles), they speak of advanced SA blockade of the second degree, type II. Frequent occurrence of long pauses is perceived as cardiac arrest and is accompanied by dizziness and loss of consciousness. The symptoms correspond to the manifestations of SSSU.

Sinoatrial block II degree II type

III degree SA block (complete SA block) is recognized using electrophysiological methods. The ECG shows a slow escape rhythm (most often the rhythm of the AV junction). Clinical symptoms may be absent or signs of regional (cerebral) hemodynamic disorders may appear with a rare replacement rhythm. TREATMENT. The occurrence of SA blockade as a result of acute cardiac pathology requires active treatment of the underlying disease. In case of significant hemodynamic disturbances as a result of SA blockade, anticholinergics, sympathomimetics, and temporary cardiac pacing are used. With persistent SA blockade, the question of permanent cardiac pacing is raised.

Sinoauricular block: severity, diagnosis and treatment

Pathological changes in conduction between the sinus node and the atrium can cause dangerous complications: complete sinoatrial blockade leads to impaired heart contractions and sudden death. Mild sinoauricular conduction disturbances are usually transient, cause loss of cardiac cycles, and are not life-threatening. But any pathological changes in conductivity in the area of the sinus node (SA block) require a full diagnosis and effective treatment. The main goal of therapy is to restore rhythm and prevent ischemia of vital organs.

Causes of the disease

The severity of external manifestations depends on the presence and quality of the impulse: sinoatrial conduction changes occur against the background of the following factors:

complete absence of impulse in the node;
low impulse force;
restriction of conduction between the node and the atrium.

The main factors causing conduction disturbances and episodes of loss of sinus node rhythm are the following conditions and diseases:

heart pathology (cardiomyopathy, myocarditis, myocardial infarction, congenital defects, chronic heart failure, atherosclerosis);
negative drug effects (side effects of some cardiovascular drugs);
toxic damage due to poisoning or severe illness (severe lack of potassium and oxygen);
tumors in the cardiovascular system;
neurovegetative reflex reactions;
mechanical damage during injuries and operations.

Any type of disturbance in the conduction of impulses in the heart requires a full diagnosis, highlighting the severity and type of cardiac pathology, which will become the basis for quality treatment.

Pathology options

There are 3 degrees of severity possible:

Sinoauricular block 1st degree - No symptoms, detected extremely rarely with the help of special studies
Sinoauricular block 2nd degree (type 1) - Gradual increase in heart block with sudden episodes of complete loss of impulses with typical manifestations on the ECG
SA blockade 2nd degree (type 2) - Irrhythmic loss of cardiac complexes with episodic and temporary complete blockades of conduction
SA block 3rd degree (complete) - Complete absence of impulses from the sinus node to the atrium

Using electrocardiography, the doctor will be able to identify a variant of pathological conduction disorder and distinguish the disease from other types of dangerous cardiac pathology.

Symptoms of the disease

With 1 degree of impaired sinoatrial conduction, there will be no signs other than a moderate decrease in heart rate. Possible manifestations of 2nd degree sinus node block include:

severe bradycardia;
circulatory disorders in the central nervous system, manifested by episodes of memory loss, dizziness and headaches;
intermittent shortness of breath;
cardiac type edema;
tendency to fainting and loss of consciousness with temporary stoppage of vital functions.

At grade 2-3, the risk of sudden death in patients with sinoauricular disorders is quite high, so it is necessary to make a timely and accurate diagnosis, ensuring that the necessary therapeutic measures are carried out.

Diagnostic tests

In addition to a routine examination, the doctor will definitely order an ECG. It is based on the results of an electrocardiographic study that the presence and severity of sinoatrial blockade can be accurately determined. With grade 1 ECG manifestations are minimal - sinus bradycardia, which normally occurs in many people and is not considered a pathology.

The first type of 2nd degree blockade on the cardiogram is expressed by periodic rhythmic loss of cardiac cycles (loss of P-P waves or the whole PQRST complex). The second type is characterized by irregular and repeated loss of P-P waves, PQRST complexes, when two or more cardiac cycles disappear, forming a pathological state of blood circulation.

Identification of typical clinical symptoms and manifestations on the electrocardiogram is a criterion for making a diagnosis and prescribing treatment, which is especially important in the complete absence of impulses and a high risk of sudden death.

Principles of treatment

Detection of sinus bradycardia does not require therapeutic measures: it is quite enough to be periodically observed by a doctor. In case of conduction disturbance of the 2nd degree, it is necessary to carry out complex therapy:

identification and treatment of heart diseases that create conditions for sinus node blockade;
removal of toxic factors and medications that negatively affect cardiac conduction of impulses;
use of symptomatic therapy;
use of cardiac pacing (surgical implantation of pacemaker).

Indications for installation of a pacemaker are:

disturbance of cerebral blood flow;
heart failure;
decrease in heart rate below 40 beats;
high risk of sudden death.

With 2-3 degrees of sinoatrial blockade, the best effect of treatment appears after surgery to install a pacemaker, and drug therapy can only provide temporary improvement and relief of symptoms.

Dangerous complications

Against the background of bradycardia and rhythm disturbances caused by blocking of impulses in the sinus node, one should be wary of the formation of the following pathological conditions:

sinus arrhythmia;
stop or failure of the sinoatrial node;
acute heart failure with edema, shortness of breath and a drop in vascular pressure;
severe disturbances of cerebral blood flow;
complete cardiac asystole;
sudden death.

Even if nothing worries you, with any type of SA blockade it is categorically unacceptable to refuse periodic visits to the doctor and regular examinations with an ECG.

If a deterioration in cardiac conduction is detected in time, it can be corrected with the help of a pacemaker and drug therapy, but if severe complications develop, it is extremely difficult to restore the lost functions of the heart and restore a person’s previous quality of life.

SA blockade 2nd degree, type 1

Sinoatrial block is a pathology of the conduction system of the heart, characterized by a disturbance in the conduction of impulses going from the sinus node to the atria.

The cause of this disturbance in the rhythm of heart contractions is atherosclerotic damage to the vessels of the heart (right coronary artery), inflammatory processes in the right atrium, followed by replacement of the site of inflammation with connective tissue, intoxication with antiarrhythmic drugs (cardiac glycosides, B blockers, etc.), myocarditis, myocardial dystrophy of metabolic-dystrophic origin, congenital heart defects, hypothyroidism.

As a result, the following pathological changes occur in the conduction system of the heart:

- The impulse in the sinus node is not produced
- The strength of the impulse coming from the sinus node is not enough to depolarize the atria
- The impulse is blocked along the path from the sinus node to the right atrium

Sinoatrial block of the 2nd degree, type I, is characterized by blocking one or more sinus impulses in a row.

Clinical picture

Clinically, 2nd degree sinoatrial block is manifested by fainting states (Morgagni–Adams–Stokes syndrome). Such fainting is characterized by the absence of convulsions and any aura, a feeling of cardiac arrest or a pronounced slowdown in its rhythm; a drop in blood pressure with cold skin and cold sweat are possible. Syncope can be triggered by a sharp turn of the head, coughing, or wearing a tight collar. Mostly they resolve on their own, but in advanced cases, resuscitation measures may be necessary.

Also worrying is a rare pulse, interruptions in the functioning of the heart, pre-fainting states with the appearance of tinnitus and severe weakness, nausea, shortness of breath when eating, and muscle weakness.

The development of bradycardia is often accompanied by a progressive course of heart failure, coronary pathology, as well as dyscirculatory encephalopathy (memory lapses, irritability, insomnia, increased dizziness, paresis, “swallowing” of words).

Diagnostics

All patients with complaints of frequent dizziness, fainting, slowing of the rhythm with a feeling of interruptions in the work of the heart undergo a mandatory examination by a cardiologist. A physical examination reveals bradycardia, arrhythmic heartbeats, and changes in blood pressure.

To confirm the diagnosis of SA blockade, ECG, HM - ECG, stress tests (treadmill test), PPSS/EPI are used. SA blockade should not be confused with 2nd degree atrioventricular block.

Treatment

First of all, the cause that caused the sinoatrial block is eliminated. All drugs that contribute to conduction disturbances are discontinued. For moderate bradycardia (beats per minute), Teopec, aminophylline, and belloid are prescribed. In emergency cases (asystole, Morgagni–Adams–Stokes attack), resuscitation measures are carried out.

With bradycardia less than 41 beats. in minutes, Morgagni-Adams-Stokes attacks, high uncorrectable blood pressure figures, SA with rhythm disturbances requiring the prescription of antiarrhythmics that suppress the sinus node, installation of a permanent pacemaker is indicated.

Forecast

The prognosis for sinoatrial block depends on the cause of the disease, the clinical picture, the patient’s age, and concomitant pathology. Properly selected drug therapy or installation of an pacemaker improves the prognosis and quality of life, but the absence of any treatment can cause Morgagni–Adams–Stokes attacks and sudden death. Also read SA blockade 2nd degree, type 2.

Right ventricular block

It often happens that the terms of cardiologists and unclear entries in the description of the ECG frighten and confuse patients, which leads to the appearance of non-existent diagnoses in everyday life. Right ventricular block is a misnomer for a completely different concept. Therefore, it would not be superfluous to clarify and understand the “blockades” and “ventricles”.

Complete right bundle branch block

The attending physician prescribed you an electrocardiogram: a beeping machine, a whole bunch of wires with suction cups and a long tape covered with mysterious curves, as a result. What do these teeth and mounds mean?

In a nutshell, unfortunately, the technique for deciphering an ECG cannot be described. However, you can and should understand the reasons and significance of the changes that a specialist will identify. For example, if we are talking about the inconvenient acronym - RBBBB, also known as complete right bundle branch block.

SA blockade 2nd degree 2nd type

Sinoatrial block is one of the types of arrhythmia when the conduction of impulses along the fibers of the heart is disrupted at the place where the connection between the sinus and atrioventricular nodes occurs. It comes in several degrees and types. This depends on the level of damage to that connection.

SA blockade 1st degree, type 2

Conduction through the sinoatrial junction in the heart can be impaired for various reasons. It comes in several degrees, each of which has a different impact on the patient’s well-being. The mildest degree of this blockade is 1st degree. This is the initial and minimal damage to the conduction system in the heart, namely its sinoatrial junction.

Brachial plexus block

Invasive techniques for the treatment of various diseases are found everywhere - such techniques are used not only by surgeons, but also by cardiologists, ophthalmologists, neurologists, and indeed in almost any field of medicine. Let's consider general issues of such a technique as blockade of the brachial plexus area.

A blockade of the brachial plexus, in ordinary language, is nothing more than “switching off” individual or groups of nerve fibers, necessary for various purposes.

Is there a 1st degree SA block, type 1 or other types?

One of the common impulse conduction disorders is the so-called sinoatrial or SA block. It should be noted that SA blockade occurs in 0.17 - 2.4% of the population, more often in adulthood and somewhat more often in women than in men.

Heel spur block

One of the common diseases of the musculoskeletal system is heel spurs. This pathology is detected in 26% of patients over 40 years of age, and in the age group over 70 years old, 88% of patients suffer from this disease.

Cervical spine block

Each of us has experienced pain in the neck at least once in our lives. There are many reasons for such pain. The most common cause is degenerative changes in the cervical spine, the so-called cervical osteochondrosis. One of the effective methods of treating neck pain is therapeutic blockades. This is the introduction of a medicinal substance into certain areas for therapeutic purposes.

Right bundle branch block

Right bundle branch block (RBBB) is a pathological disorder in the conduction system of the heart in which the conduction of electrical impulses from the atrioventricular node to the right ventricle is slow or absent. There are complete and partial blockade of the right leg of the bundle of His.

Chest discomfort

Patients often come to the doctor complaining of discomfort in the chest area. There are many reasons for this symptom to occur. First of all, the doctor will think about possible myocardial ischemia, when there is insufficient oxygen supply to the heart muscle. This happens for many reasons, primarily an increase in cholesterol in the blood, dietary errors, hypertension, and hereditary factors.

Atrioventricular block 2nd degree

Atrioventricular block of the second degree or heart block of the second degree is characterized by a violation, delay or interruption of the conduction of the atrial impulse through the atrioventricular node to the ventricles.

First aid for arrhythmia

Each of us periodically, during or after physical activity, sometimes during complete rest during sleep, experiences sensations in the heart area in the form of interruptions, fading, and rapid heartbeat. This does not necessarily mean that there is any heart disease. Even healthy people experience heart failure, but this is rare and, as a rule, does not last long and goes away on its own.

Sa blockade 2nd degree, type 1

SA blockade of the first degree: indistinguishable on a surface ECG.

Second degree SA block:

Type I: gradual shortening of the PR interval leading to loss of the P wave and QRS complex

Type II: repeated loss of P waves and QRS complexes

SA blockade of the third degree: sequential loss of several P waves and QRS complexes at once

Sinoatrial block is a relatively rare cardiac arrhythmia. It is characterized by a violation of conduction between the sinus node and the atrium. As with AV block, there are 3 types of SA block.

I. SA blockade of the 1st degree

The conduction time of excitation from the sinus node to the atria is prolonged. However, this prolongation is not visible on the surface ECG, and the block itself has no clinical significance.

II. SA blockade II degree

SA blockade of the second degree, type I (SA-Wenckebach period). Rarely observed. Similar to second degree AV block (Wenckebach period), as the sinoatrial conduction time gradually increases, the cardiac complex (P wave and QRS complex) falls out. The pause that occurs is shorter than the double PP interval.

SA blockade of the second degree, type II. The occasional loss of sinoatrial conduction is characteristic. On the ECG this is manifested by the loss of the P wave and the corresponding QRS complex.

Second degree sinoatrial block (type II) is sometimes combined with another rhythm disorder, in particular sinus arrhythmia, which makes ECG interpretation difficult. If there is a significant decrease in the frequency of ventricular contractions, it is necessary to discuss the implantation of a pacemaker.

SA blockade of the second degree, type II.

The first 2 complexes correspond to sinus rhythm, then there is a sudden loss of the entire atrioventricular complex, after which the heart contracts again in sinus rhythm.

After the 5th cardiac complex, prolapse of the entire atrioventricular complex is again observed. Belt speed 25 mm/s.

III. III degree SA block (complete SA block)

Third degree sinoatrial block is also called complete SA block. When analyzing the ECG, loss of the P wave and the QRS complex is noted for some time; During this period of time, blood circulation stops. Characteristic of third degree SA block is the intermittent appearance of pauses after the loss of the sinus complex, i.e. short ventricular asystole. This is the reason why patients complain of dizziness. In these cases, implantation of a pacemaker is also indicated.

Sinus arrest is often indistinguishable from complete SA block.

The causes of SA blockade are often coronary artery disease, heart defects, myocarditis and sick sinus syndrome (sinus node dysfunction, manifested by pronounced sinus bradycardia and SA blockade).

Complete SA block (sinus node arrest).

A 71-year-old patient complains of seizures associated with epilepsy diagnosed 2 years ago.

During ECG recording, a convulsive seizure occurred, the asystolic pause was 7.5 s. Complete SA blockade.

The frequency of ventricular contractions is per minute.

Due to the low frequency of ventricular contractions, an escape rhythm appears in the upper part of the AV junction (see limb leads) and partially in the middle part of the AV junction (not shown in the figure).

Complete blockade of PNPG. In this case, we can assume a complete SA blockade with an escape rhythm.

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SINOATRIAL (SA) BLOCK is characterized by a disturbance in the conduction of impulses from the sinus node to the atria.

THE ETIOLOGY of SA blockades largely coincides with the etiology of sick sinus syndrome (SSNS) and other sinus dysfunctions - these are degenerative calcifying lesions of intracardiac structures, numerous and varied myocardial pathologies, regulatory dysfunctions (excessive vagotonia), toxic (including drug) effects. SA blockade may be one of the manifestations of SSSS.

ECG DIAGNOSTICS. With SA block of the first degree, a slowdown in the conduction of impulses from the SA node to the atrial myocardium is observed. But an ECG study does not reveal this, because An external ECG does not record excitation of the sinus node, and the P wave is formed by depolarization of the atrial myocardium. Sinoatrial conduction time can only be assessed using special electrocardiographic methods. 1st degree SA block has no clinical manifestations.

SA block of the second degree (incomplete SA block) is characterized by blocking of one or more sinus impulses in a row. This is manifested by the loss of one or more sinus cycles (P waves and rUD complexes). The pauses that occur can be multiples of 2, less often 3-4, of the main R-R intervals, but are often interrupted by passive slipping complexes or rhythms. In the clinical and electrocardiographic characteristics of second degree SA block, two main types are distinguished:

SA blockade of the second degree, type I (Wenckenbach period in the SA junction) is characterized by loss of the sinus complex, which is preceded by a consistent shortening of the P-P intervals (Fig. 47). With this option, there is a progressive increase from cycle to cycle in the time of impulse conduction from the sinus node to the atrial myocardium, ending with complete blocking of the next impulse. At this moment, a pause is recorded, including a blocked impulse. The increase in conduction time in this periodical is maximum in its first cycles after a pause. Although in the future the conduction progressively worsens, the increase in this time (increment) decreases from complex to complex. In this regard, the ECG reveals a gradual shortening of the P-P intervals and after the shortest interval a pause occurs as a result of blocking one impulse in the SA junction. This pause is shorter than twice the P-R interval preceding the pause. Classical periodicals of Wenkenbach are less common than atypical periodicals with disordered fluctuations of P-P intervals or their progressive lengthening with blocking of the next sinus impulse. With repeated Wenckenbach periods, regular ratios are established between the number of sinus impulses and P waves - 3:2, 4:3, etc. At the moment the sinus impulse is blocked, the next P wave and QRS complex are absent on the ECG. Children at the time of loss of the cardiac cycle may feel a sinking heart, sometimes accompanied by dizziness. This variant of SA block is usually benign in nature.

TREATMENT. The occurrence of SA blockade as a result of acute cardiac pathology requires active treatment of the underlying disease. In case of significant hemodynamic disturbances as a result of SA blockade, anticholinergics, sympathomimetics, and temporary cardiac pacing are used. With persistent SA blockade, the question of permanent cardiac pacing is raised.

SA blockade 2nd degree 2nd type

Reasons for the blockade

About half of the cases of arrhythmia do not have a specific cause, and it occurs on its own. It can also be caused by the following reasons:

1 – chronic heart diseases, such as ischemic disease and myocardial cardiosclerosis. These diseases most often cause sinoatrial block;

2 – acute processes in the heart, such as myocardial infarction and acute myocarditis, can cause temporary or permanent disruption of the passage of electrical impulses in the sinoatrial junction;

3 – lesions of the heart valves in the form of defects can increase the load on the heart muscle, as a result of which overload can occur anywhere in the impulse conduction system, including in the connection between the sinus and atrioventricular nodes;

4 – high vagal tone can lead to sinoatrial blockade. It can occur due to tumors, inflammation or vascular disorders in the brain. Also, frequent reflex stimulation of the vagus nerve in order to relieve other types of arrhythmias can lead to constant high tone;

5 – disturbances in the hormonal balance (thyroid hormones) and electrolyte composition (large amounts of potassium) in the blood plasma can also provoke the formation of a blockade;

6 – hypertension also increases the load on cardiac activity, which can lead to this blockade;

7 – hereditary predisposition also plays an important role in the formation of blockade;

8 – some drugs against arrhythmia (quinidine, cordarone, cardiac glycosides, beta-blockers) can lead to the formation of blockade, including type 2 sinoatrial blockade. They must be taken carefully and strictly follow the regimen prescribed by the doctor.

Symptoms of SA blockade 2 degrees 2 types

Block of the sinoatrial junction of the 2nd degree, type 2, causes the following manifestations. First, there are interruptions in the functioning of the heart. These interruptions occur as extrasystoles. As a rule, patients feel them. You can also follow them by feeling the pulse. Against the background of a normal rhythmic pulse, an extraordinary beat suddenly appears, almost immediately after a normal beat. After which there is a long pause when there is not a single blow. At this moment, the patient feels a sinking feeling in his heart. At this time, there is no heartbeat, and the next portion of blood does not enter the brain. All this causes dizziness. SA blockade should not be confused with 2nd degree atrioventricular block.

With an advanced or untreated form of sinoatrial arrhythmia of the 2nd degree, type 2, such episodes of cardiac arrest can be repeated much more often, as a result of which blood increasingly does not flow to the brain, and attacks of loss of consciousness occur. And with a long interval after extraordinary contractions, sudden clinical death may occur.

Treatment

If interruptions due to this blockade are single and rare, then this does not require special treatment. All you need is observation. In more severe forms of blockade, when there are manifestations of it, it is necessary to treat the underlying disease that led to this arrhythmia. If it was a result of taking medications, then you need to stop taking them. If this happened due to high tone of the vagus nerve, then you need to take medications to reduce it.

Elimination of hormonal imbalance and correction of electrolyte composition will help cope with arrhythmia, if this was its cause. With frequent loss of consciousness and a history of clinical death due to sinoatrial arrhythmia of the 2nd degree, type 2, temporary or permanent electrical pulse therapy will help. Read also the article by a cardiologist about 2nd degree SA blockade, type 1.

Consequences of heart bypass surgery

Cardiac bypass, or more precisely coronary artery bypass, is a very common procedure for patients suffering from coronary heart disease. It is the only method of improving a person’s quality of life when medications do not help and the disease progresses.

Recovery after cardiac bypass surgery

Heart bypass surgery, or coronary artery bypass grafting, is now being used more and more often. The operation is performed for coronary heart disease, in case of significant blockage of the vessels directly feeding the heart muscle.

Cardiac bypass surgery after a heart attack

Unfortunately, cardiovascular diseases today occupy a leading place among other human diseases. They are also the most common cause of death among people of working age (especially men).

SA blockade 1st degree, type 2

Right bundle branch block

Atrioventricular block 2nd degree

Is there a 1st degree SA block, type 1 or other types?

Complete left bundle branch block

The bundle of His can be described as a collection of cardiac cells that is divided into two parts (branch): right and left. It is located behind the atrioventricular node. The left leg has its own branches, which are connected to each other by anastomosis. The legs, having reached the ventricular myocardium, are divided into bundles of adductor cardiac cells, also called Purkinje fibers.

Incomplete right bundle branch block

Incomplete right bundle branch block (abbreviated as RBBB) is a partial disruption of the passage of electrical impulses through the right bundle branch.

SA blockade 2nd degree, type 1

Sinoatrial block is a pathology of the conduction system of the heart, characterized by a disturbance in the conduction of impulses going from the sinus node to the atria.

Consequences of complete blockade of the left bundle branch

The heart is a unique organ that governs itself, i.e. has automaticity, but, of course, taking into account the needs of the body and not without interfering with the work of the nervous and endocrine systems. This organ is not just a muscle sac, which is a pump for pumping blood; the heart is much more complex than it might seem.

First aid for arrhythmia

Sinoatrial block (SA): what it is, causes, symptoms, ECG, treatment

Sinoatrial block (sinoauricular, SA block) is considered one of the variants of sick sinus syndrome (SU). This type of arrhythmia can be diagnosed at any age; it is recorded somewhat more often in males; it is relatively rare in the general population.

In a healthy heart, the electrical charge is generated in the sinus node, which is located deep in the right atrium. From there it spreads to the atrioventricular node and the bundle branches. Due to the sequential passage of the impulse through the conductive fibers of the heart, the correct contraction of its chambers is achieved. If an obstacle arises in any of the areas, then the reduction will also be disrupted, then we are talking about a blockade.

With sinoatrial blockade, the reproduction or propagation of the impulse to the underlying parts of the conduction system from the main, sinus node is disrupted, therefore the contraction of both the atria and ventricles is disrupted. At a certain moment, the heart “misses” the impulse it needs and does not contract at all.

Different degrees of sinoatrial block require different therapeutic approaches. This disorder may not manifest itself at all, or may cause fainting and even death of the patient. In some cases, sinoatrial blockade is permanent, in others it is transient. In the absence of a clinic, you can limit yourself to observation; a 2-3 degree blockade requires appropriate treatment.

Causes of sinoatrial block

Among the main mechanisms of sinoauricular blockade are damage to the node itself, disruption of the propagation of impulses through the heart muscle, and changes in the tone of the vagus nerve.

In some cases, the impulse is not formed at all, in others it is there, but too weak to cause contraction of cardiomyocytes. In patients with organic damage to the myocardium, the impulse encounters a mechanical obstacle in its path and cannot pass further along the conducting fibers. Insufficient sensitivity of cardiomyocytes to electrical impulses is also possible.

Factors leading to sinoauricular block are considered:

Heart defects;
Inflammatory changes in the heart (myocarditis);
Cardiovascular form of rheumatism;
Secondary damage to heart tissue due to leukemia and other neoplasms, injuries;
Coronary heart disease (cardiosclerosis, post-infarction scar);
Myocardial necrosis (infarction);
Cardiomyopathy;
Vagotonia;
Intoxication with drugs when the permissible dose is exceeded or individual intolerance - cardiac glycosides, verapamil, amiodarone, quinidine, beta-blockers;
Organophosphorus poisoning.

The operation of the SA is influenced by the activity of the vagus nerve, therefore, when it is activated, impulse generation may be disrupted and SA blockade may occur. Usually in this case they talk about transient SA blockade, which appears on its own and goes away in the same way. This phenomenon is possible in practically healthy people, without anatomical changes in the heart itself. In isolated cases, idiopathic sinoauricular block is diagnosed when the exact cause of the pathology cannot be determined.

In children, conduction disturbances from the sinoatrial node are also possible. Typically, such arrhythmia is detected after 7 years of age, and a common cause is autonomic dysfunction, that is, the blockade is more likely to be transient, against the background of increased tone of the vagus nerve. Among the organic changes in the myocardium that can cause this type of blockade in a child are myocarditis, myocardial dystrophy, in which, along with SA blockade, other types of arrhythmias can be detected.

Types (types and degrees) of sinoatrial blockade

Depending on the severity of the arrhythmia, there are several degrees of it:

SA blockade 1st degree (incomplete), when changes are minimal.
SA blockade 2nd degree (incomplete).
SA blockade 3rd degree (complete) is the most severe, the contraction of both the ventricles and atria is impaired.

With 1st degree block of the sinus node, the node functions, and all impulses cause contraction of the atrial myocardium, but this happens less frequently than normal. The impulse through the node passes more slowly, and therefore the heart contracts less often. It is impossible to record this degree of blockade on an ECG, but it is indirectly indicated by rarer, as expected, heart contractions – bradycardia.

With sinoatrial blockade of the 2nd degree, the impulse is no longer always formed, resulting in a periodic absence of contraction of the atria and ventricles of the heart. It, in turn, comes in two types:

SA blockade 2nd degree, type 1 - the conduction of the electrical signal through the sinus node gradually slows down, as a result of which the next contraction of the heart does not occur. The periods of increase in the pulse conduction time are called Samoilov-Wenckebach periods;
SA blockade of the 2nd degree, type 2 – contraction of all parts of the heart occurs after a certain number of normal contractions, that is, without periodic slowing down the movement of the impulse along the SA node;

Sinoauricular block of the 3rd degree is complete, when the next heart contraction does not occur due to the lack of impulses from the sinus node.

The first two degrees of blockade are called incomplete, since the sinus node, although abnormal, continues to function. The third degree is complete, when impulses do not reach the atria.

Features of ECG with SA blockade

Electrocardiography is the main way to detect heart blocks, through which uncoordinated activity of the sinus node is detected.

SA blockade of the 1st degree does not have characteristic ECG signs; it can be suspected by bradycardia, which often accompanies such blockade, or shortening of the PQ interval (not a constant sign).

The presence of SA blockade can be reliably confirmed by ECG starting from the second degree of disorder, in which full cardiac contraction does not occur, including the atria and ventricles.

On the ECG at stage 2 the following are recorded:

Lengthening the interval between atrial contractions (A-P), and during the loss of one of the next contractions this interval will be two or more normal;
Gradual decrease in R-R time after pauses;
Absence of one of the next PQRST complexes;
During long periods of absence of impulses, contractions may occur generated from other sources of rhythm (atrioventricular node, bundle branches);
If not one, but several contractions occur at once, the duration of the pause will be equal to several R-R, as if they were occurring normally.

Complete blockade of the sinoatrial node (3rd degree), is considered when an isoline is recorded on the ECG, that is, there are no signs of electrical activity of the heart and its contraction, and is considered one of the most dangerous types of arrhythmia, when there is a high probability of death of the patient during asystole.

Manifestations and diagnostic methods of SA blockade

The symptoms of sinoatrial block are determined by the severity of disorders in the conductive fibers of the heart. In the first degree, there are no signs of blockade, as well as the patient’s complaints. With bradycardia, the body “gets used” to a rare pulse, so most patients do not experience any worries.

SA blockades of 2 and 3 degrees are accompanied by tinnitus, dizziness, discomfort in the chest, and shortness of breath. Against the background of a slower rhythm, general weakness is possible. If SA blockade has developed due to a structural change in the heart muscle (cardiosclerosis, inflammation), then an increase in heart failure is possible with the appearance of edema, cyanosis of the skin, shortness of breath, decreased performance, and enlarged liver.

In a child, the signs of SA blockade differ little from those in adults. Parents often pay attention to decreased performance and fatigue, blue discoloration of the nasolabial triangle, and fainting in children. This is the reason to contact a cardiologist.

If the interval between heart contractions is too long, then Morgagni-Adams-Stokes (MAS) paroxysms may occur, when the flow of arterial blood to the brain is sharply reduced. This phenomenon is accompanied by dizziness, loss of consciousness, noise, ringing in the ears, possible convulsive muscle contractions, involuntary emptying of the bladder and rectum as a result of severe brain hypoxia.

syncope with MAS syndrome due to sinus node blockade

Suspicion of the presence of a blockade in the heart arises already during auscultation, during which the cardiologist records bradycardia or loss of the next contraction. To confirm the diagnosis of sinoauricular block, the main methods are electrocardiography and 24-hour monitoring.

Holter monitoring can be performed for 72 hours. Long-term ECG monitoring is important in those patients in whom, if the presence of arrhythmia is suspected, no changes could be detected in a regular cardiogram. During the study, a transient blockade, an episode of SA blockade at night or during physical activity may be recorded.

Children also undergo Holter monitoring. The detection of pauses lasting more than 3 seconds and bradycardia of less than 40 beats per minute is considered diagnostically significant.

A test with atropine is indicative. The introduction of this substance to a healthy person will cause an increase in the frequency of heart contractions, and with SA blockade, the pulse will first double, and then just as rapidly decrease - a blockade will occur.

To exclude other cardiac pathologies or search for the cause of the blockage, an ultrasound of the heart can be performed, which will show the defect, structural changes in the myocardium, scarring area, etc.

Treatment

1st degree SA blockade does not require specific therapy. Usually, to normalize the rhythm, it is enough to treat the underlying disease that caused the blockade, normalize the daily routine and lifestyle, or discontinue medications that could disrupt the automatism of the sinus node.

Transient SA blockade against the background of increased activity of the vagus nerve is well treated by prescribing atropine and its drugs - bellataminal, amizil. The same medications are used in pediatric practice for vagotonia, which causes transient blockade of the sinus node.

Attacks of SA blockade can be treated medicinally with atropine, platyphylline, nitrates, nifedipine, but, as practice shows, the effect of conservative treatment is only temporary.

Patients with sinus node blockade are prescribed metabolic therapy aimed at improving myocardial trophism - riboxin, mildronate, cocarboxylase, vitamin and mineral complexes.

If SA blockade is recorded, you should not take beta blockers, cardiac glycosides, cordarone, amiodarone, or potassium supplements, as they can cause even greater difficulty in the automaticity of the SA and worsen bradycardia.

If blockade of the SA node leads to pronounced changes in well-being, causes an increase in heart failure, and is often accompanied by fainting with a high risk of cardiac arrest, then the patient is offered to have a pacemaker implanted. Indications may also include Morgagni-Adams-Stokes attacks and bradycardia below 40 beats every minute.

In case of sudden severe blockade with Mroganyi-Adams-Stokes attacks, temporary cardiac stimulation is necessary, chest compressions and artificial ventilation are indicated, atropine and adrenaline are administered. In other words, a patient with such attacks may require full resuscitation measures.

If the exact reasons for the development of sinoatrial block have not been established, there are no effective measures to prevent this phenomenon. Patients who have already recorded changes in the ECG should correct them with the help of medications prescribed by the cardiologist, normalize their lifestyle, and also regularly visit the doctor and have an ECG taken.

Children with arrhythmias are often advised to reduce the overall level of exercise and reduce participation in sports sections and clubs. Visiting children's institutions is not contraindicated, although there are experts who advise limiting the child in this too. If there is no risk to life, and episodes of SA blockade are rather isolated and transient, then there is no point in isolating the child from school or going to kindergarten, but observation at the clinic and regular examination are necessary.

The danger of sinoauricular block and methods of its treatment

Sinoatrial or sinoauricular block is a form of heart rhythm disorder. Impulses are generated in the sinus node, but do not propagate through the atria. As a result, the heart does not contract. Clinically, this condition can manifest as syncope and in some cases requires the installation of a pacemaker.

What is

Normal heartbeat is controlled by electrical signals that are regularly produced in the sinus node. This cluster of special cells is located in the upper part of the right atrium. From there, the impulse spreads through the atria, causing their excitation and contraction. As a result, blood is pushed out of them into the ventricles.

The conduction system of the heart is normal

With sinoatrial (SA) block, the impulse is delayed or blocked at exit from the sinus node. In the latter case, it does not enter the conduction system of the atria and does not pass further into the ventricles.

And here is more information about the treatment and symptoms of atrial extrasystole.

Reasons for development

In young people, such conduction disturbances may be associated with increased excitability of the vagus nerve and the predominance of the parasympathetic system. During daily ECG monitoring, pauses are detected, usually during sleep. This condition is not life-threatening, but can limit the professional suitability of a young person.

Extracardiac causes of pathology:

damage to the sympathetic or parasympathetic nerve trunks during operations on the chest or abdominal organs;

brain tumor;

intracranial hypertension (increased cerebrospinal fluid pressure in the cavities of the ventricles of the brain);

hypothyroidism (insufficient production of thyroid hormones);

progressive liver diseases (hepatitis or cirrhosis);

hyperkalemia (increased potassium concentration in the blood, for example, with renal failure).

SA blockade can be caused by heart diseases:

ischemic cardiomyopathy caused by ischemic heart disease or the consequences of myocardial infarction;

myocarditis;

pericarditis;

myocardial amyloidosis (impregnation with protein masses, for example, in chronic osteomyelitis);

age-related changes associated with atherosclerosis of the coronary vessels.

This rhythm disturbance is one of the manifestations of sick sinus syndrome (SSNS). The disease is accompanied by a disruption in the production of normal impulses, a slow heartbeat, attacks of tachycardia and the formation of long pauses.

Sinoauricular block can be caused by an overdose of the following medications:

In many cases, it is not possible to determine the exact cause of the pathology.

Degrees of manifestation and their features

First degree sinoatrial block is a delay in the output of the electrical signal. In this case, the time required for the excitation to spread to the atria increases. At this stage, sinoauricular block does not appear on the ECG. It can only be diagnosed using electrophysiological testing (EPS).

SA blockade of the 2nd degree is characterized by periodic complete cessation of impulse flow into the atria. This is accompanied by the absence of the P wave and the ventricular complex on the ECG. There is a pause in the work of the heart.

Sinoauricular block of the 3rd degree is characterized by the absence of several sinus impulses. The ECG records a long pause, which usually ends with the formation of a replacement rhythm. Its source is the underlying portion of the conduction system, located in the atria. Ectopic atrial rhythm usually has a frequency of one minute.

If a replacement rhythm is not formed, the heart stops working. The brain experiences a lack of oxygen. This is accompanied by loss of consciousness.

To see how sinoatrial block looks on an ECG and the mechanism of its development, watch this video:

Symptoms of pathology

1st degree SA blockade has no clinical manifestations.

Second degree sinoauricular block is usually well tolerated by the patient. Sometimes the patient complains of a feeling of interruptions, a sinking heart, and slight dizziness. Clinical symptoms are associated primarily with the underlying disease (eg, myocarditis).

With complete SA blockade, attacks of weakness, dizziness, and sudden loss of consciousness may occur. In such cases, doctors decide to implant a pacemaker in the patient.

Diagnostics

An ECG taken at rest can detect manifestations of 2nd and 3rd degree SA blockade.

Sinoauricular block of the 2nd degree, type 1, is associated with a gradual slowdown in the output of the impulse from the sinus node. The cardiogram shows an increasing shortening of the intervals between the P waves, and after the shortest interval a pause appears. It is shorter than the previous P-P interval multiplied by 2.

Second degree sinoauricular block type 2 is caused by a sudden blockage of the electrical signal output. A pause occurs equal to twice the interval between adjacent P waves. If a 2:1 blockade appears, then every second P wave falls out, and sinus bradycardia is recorded on the cardiogram. The presence of SA blockade can be suspected given the low heart rate per minute.

Complete SA blockade on the ECG is characterized by the absence of atrial contractions and the formation of a replacement atrial or AV nodal rhythm.

a) Sinoauricular block 2nd degree, type 1; b) Sinoauricular block 2nd degree, type 2; c) Complete SA blockade

For a better diagnosis of such arrhythmia, Holter cardiogram monitoring is prescribed. The method makes it possible to determine the average heart rate and calculate the number and duration of pauses. The cardiologist needs these characteristics to determine whether the patient requires a pacemaker.

Treatment of pathology

SA blockade of the 1st and 2nd degrees does not require treatment. Treatment is carried out for the disease that caused conduction disturbances.

Treatment of 3rd degree sinoauricular block includes 3 stages:

For suddenly developed SA blockade, atropine is used. This medicine suppresses the activity of the parasympathetic nervous system, speeds up the heartbeat, and increases the efficiency of blood circulation. Ephedrine and norepinephrine stimulate the sympathetic nervous system, increasing heart rate and improving blood flow. These medications are used as emergency measures only.

The main treatment method for 3rd degree SA block is implantation of a pacemaker. It is placed under the skin of the chest and its electrodes are inserted into the heart. They produce electrical impulses, replacing the normal functioning of the sinus node. Cardiac stimulation allows you to completely eliminate the manifestations of arrhythmia.

Forecast

SA blockade itself practically does not cause serious complications. The SSSU, of which it is a part, is dangerous. This disease may cause:

Implanting a pacemaker eliminates the risk of these complications.

In other cases, the prognosis for SA blockade is determined by the underlying disease (myocardial infarction, cardiosclerosis, myocarditis, etc.).

And here is more information about atrioventricular block.

Prevention

Sinoatrial block is not a disease, but only a syndrome that complicates the course of various diseases. Therefore, its prevention comes down to eliminating risk factors for cardiovascular pathology (smoking, excess weight, physical inactivity, high blood pressure).

Non-cardiac diseases that can cause this arrhythmia should be treated promptly, and self-medication with antiarrhythmic medications should be avoided.

Sinoauricular block is a violation of heart contractions caused by a slowdown or cessation of the output of the stimulating signal from the sinus node. Complete SA blockade, which is accompanied by oxygen starvation of the brain, is dangerous. The main method of eliminating pathology is electrical cardiac stimulation.

Phase sinus arrhythmia in combination with AV block 2:1. . The danger of sinoauricular block and methods of its treatment.

Sinoauricular block: manifestations on the ecg. Atrial flutter: forms, signs of fibrillation.

Congenital or acquired atrioventricular block: degrees of disease development, treatment. The danger of sinoauricular block and its methods.

The danger of sinoauricular block and methods of its treatment. Rules for life after installation of a pacemaker.

Physiological second degree atrioventricular block occurs. If atrial impulse blockade occurs regularly, the ventricles contract.

We will publish information soon.

Causes, types and treatment of sinoatrial blockade

Sinoatrial block is characterized by a disturbance in the conduction of impulses emanating from the sinus node to the atria. Due to this pathology, the frequency of contractions of the heart muscle is disrupted. In this case, sinoatrial blockade can be caused by both ischemic disease and intoxication of the body. In the process of its development, the cardiovascular system is primarily affected. Then, due to increasing interruptions in blood supply, pathologies of internal organs and tissues begin to develop.

Thus, SA blockade can disrupt the functioning of all systems of the human body. Ultimately, this can lead to pre-infarction and death.

Causes

There are several reasons why a patient begins to develop this disease:

difficulty passing the impulse from the sinus node to the atria;
insufficient pulse power;
decreased sensitivity of the atria to impulse;
cessation of impulse formation in the sinus node.

All these disturbances in the functioning of the heart, as a rule, occur during degenerative processes that take place in the area of the sinus node. The following factors can provoke them:

vascular atherosclerosis;
Congenital heart defect;
myocarditis (viral);
leukemia;
heart tumors;
rheumatism;
disorder of the autonomic system;
intoxication with medications.

The last point should be considered separately. Medical practice shows that the patient himself often provokes the development of SA blockade by taking certain medications. These primarily include beta-blockers, glycosides, Amiodarone and Verapamil. An overdose of these drugs leads to the development of intoxication and initiation of inflammatory processes in the area of the sinus node. People who have an individual intolerance to certain components of the drugs may be especially affected.

Another reason for the development of sinoatrial block may be pathological irritation of the vagus nerve. If its tone increases excessively, the permeability of the impulse to the atria may decrease. Most often, young people who have problems with the functioning of the autonomic system suffer from this pathology.

Types of disease

Today, experts distinguish three degrees of development of SA blockade: I, II and III.

The first degree is very difficult to diagnose and cannot be detected by a surface ECG. It can only be detected during an examination using intracardiac EPI. As the pathology develops, it becomes much easier to diagnose it: the disease begins to be accompanied by typical symptoms. At the same time, disturbances in the conduction rhythm of the heart make themselves felt.

Second degree sinoatrial block is divided into two types.

The first type is characterized by a gradual decrease in the conductivity of the sinus node. The patient does not yet feel a change in pulse, and his sensations are initially limited to weakness and periodic dizziness. As the disease progresses, he increasingly experiences presyncope. As a rule, they are provoked by turning the head, severe coughing and increased physical activity. Loss of consciousness in such cases does not last long, and the patient can come to his senses on his own.
With second degree sinoatrial block of the second type, the patient may experience frequent delays in the heart. As a rule, after the next contraction, the heart immediately contracts again, after which there is a long pause. At this moment, the person experiences dizziness and weakness due to blood deficiency. The brain, not receiving enough oxygen, can temporarily turn off consciousness, causing fainting. In some cases, the patient may not only lose consciousness during another cardiac pause, but also die.

The last, III degree of the disease is the most dangerous and is characterized by complete blockade of impulse conduction. The patient's heart enters an "escaping" replacement rhythm, characteristic of asystole. When used as a diagnostic ECG, you can see that there are no PQRST complexes as such on the graph. A person experiences complete sinoatrial block, and the heart stops receiving impulses from the sinus node.

Treatment

The choice of drugs to treat sinoatrial block directly depends on the degree of its development. Thus, in stage I, the patient is not subject to drug treatment, being under the supervision of the attending physician. Therapy comes down to eliminating the causes that led to the development of pathology. In stages II and III of the disease, as a rule, potent drugs and therapeutic procedures are prescribed. Most often used to combat SA blockade:

All of these drugs cause a short-term increase in heart rate and should be taken regularly as recommended by a doctor. Unfortunately, many patients have individual intolerance to the components of certain medications. In such cases, drug treatment is completely replaced by medical procedures. The most effective of them include:

atrial pacing in AAI mode;
carotid sinus massage;
pressing on the eyeballs.

In severe cases, intensive care is used to save the patient's life. The patient is connected to the artificial lung ventilation system and closed heart massage is performed.

Cardiologist

Higher education:

Cardiologist

Kuban State Medical University (KubSMU, KubSMA, KubGMI)

Level of education - Specialist

Additional education:

“Cardiology”, “Course on magnetic resonance imaging of the cardiovascular system”

Research Institute of Cardiology named after. A.L. Myasnikova

"Course on functional diagnostics"

NTsSSKh them. A. N. Bakuleva

"Course in Clinical Pharmacology"

Russian Medical Academy of Postgraduate Education

"Emergency Cardiology"

Cantonal Hospital of Geneva, Geneva (Switzerland)

"Therapy course"

Russian State Medical Institute of Roszdrav

With transient 2nd degree AV block, the conduction of electrical impulses from the atria to the ventricles is partially disrupted. Atrioventricular block sometimes occurs without visible symptoms and may be accompanied by weakness, dizziness, angina, and in some cases loss of consciousness. The AV node is part of the conduction system of the heart, which ensures the sequential contraction of the atria and ventricles. When the AV node is damaged, the electrical impulse slows down or does not arrive at all and, as a result, a malfunction of the organ occurs.

Causes and extent of the disease

Second degree atrioventricular block can also be observed in healthy trained people. This condition develops during rest and goes away with physical activity. The most susceptible to this pathology are elderly people and people with organic heart disease:

ischemic disease;
myocardial infarction;
heart disease;
myocarditis;
heart tumor.

Sometimes the disease develops due to an overdose of drugs; congenital pathology is less common. The cause of atrioventricular block can be surgical interventions: insertion of a catheter into the right side of the heart, valve replacement, organ plastic surgery. Diseases of the endocrine system and infectious diseases contribute to the development of 2nd degree blockade.

In medicine, atrioventricular blocks are divided into 3 degrees. The clinical picture at stage 1 of the disease does not have pronounced symptoms. In this case, the passage of impulses in the organ area slows down.

Stage 2 is characterized by slowing down and partial passage of sinus impulses; as a result, the ventricles do not receive a signal and are not excited. Depending on the degree of loss of impulses, there are several options for 2nd degree blockade:

Mobitz 1 is characterized by a gradual lengthening of the P-Q interval, where the ratio of P waves and QRS complexes is 3:2, 4:3, 5:4, 6:5, etc.
Another variant, Mobitz 2, is characterized by incomplete blockade with a constant P-Q interval. After one or two pulses, the conductivity of the system deteriorates, and the third signal no longer arrives.
Option 3 implies a high degree of blockade 3:1, 2:1. During diagnosis, every second pulse that does not pass through is lost on the electrocardiogram. This condition leads the patient to a slow heart rate and bradycardia.

AV block (grade 2) with further deterioration leads to complete blockage, when not a single impulse passes to the ventricles. This condition is typical for stage 3 of the disease.

Symptoms and treatment

Symptoms of the pathology develop against the background of a rare heartbeat and circulatory disorders. Due to insufficient blood flow to the brain, dizziness occurs and the patient may lose consciousness for a while. The patient feels rare powerful tremors in the chest, and the pulse slows down.

When assessing the patient’s condition, the specialist finds out whether he has had previous heart attacks, cardiovascular diseases, and a list of medications taken. The main research method is electrocardiography, which allows you to capture and graphically reproduce the work of the cardiac system. Daily Holter monitoring allows you to assess the patient’s condition at rest and during light physical activity.

Additional studies are carried out using echocardiography, multispiral computed cardiography and magnetic resonance imaging.

If AV block (grade 2) occurs for the first time, the patient is prescribed a course of drug therapy. All medications that slow down impulse conduction are discontinued. Drugs are prescribed that increase the heart rate and block the influence of the nervous system on the sinus node. These drugs include: Atropine, Isadrine, Glucagon and Prednisolone. In cases of chronic disease, Belloid and Corinfar are additionally prescribed. Teopek is recommended for pregnant women and people suffering from epilepsy. The dosage is prescribed by the doctor depending on the patient’s condition.

Long-term heart failure contributes to the accumulation of fluid in the body. To eliminate congestion, take the diuretics Furosemide and Hydrochlorothiazide.

A severe form of the disease with 2nd degree AV block of the Mobitz type 2 requires radical treatment. For this purpose, an operation is performed to install a pacemaker - a device that controls the rhythm and frequency of the heart. Indications for surgery:

clinical picture of the patient’s condition with frequent fainting;
AV block (degree 2) Mobitz type 2;
Morgagni-Adams-Stokes attack;
heart rate less than 40 beats per minute;
heart failures with a frequency of more than 3 seconds.

Modern medicine uses the latest devices that work on demand: electrodes release pulses only when the heart rate begins to fall. The operation causes minimal damage and is performed under local anesthesia. After installing the stimulator, patients' pulse normalizes, pain disappears and their well-being improves. Patients must follow all doctor's instructions and visit a cardiologist. The operating life of the device is 7-10 years.

Forecast and prevention of the disease

In the chronic course of the pathology, serious complications are possible. Patients develop heart failure, kidney disease, arrhythmia and tachycardia, and there are cases of myocardial infarction. Poor blood supply to the brain leads to dizziness and fainting, and may impair intellectual activity. A Morgagni-Adams-Stokes attack becomes dangerous for a person, the symptoms of which are fever, pale skin, nausea and fainting. In such cases, the patient needs urgent help: cardiac massage, artificial respiration, calling intensive care. The attack can result in cardiac arrest and death.

Prevention of the disease consists of timely treatment of heart pathologies, hypertension, and control of blood sugar levels. It is necessary to avoid stress and overexertion.

In case of second degree AV block, the following is prohibited:

engage in professional sports;
be exposed to excessive physical exertion;
smoke and drink alcohol;
After installing a pacemaker, avoid electrical and electromagnetic fields, physiotherapeutic procedures and injuries to the chest area.

A routine electrocardiogram will help identify the disease in the early stages and carry out conservative treatment, which will contribute to the person’s full recovery and return to a normal lifestyle.

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.