Bradycardia at night and sa block. Sinus heart block

Sinoauricular or sinoarterial blockade is a type of intracardiac conduction disorder. This condition is characterized by a slow speed or complete cessation of the transmission of the cardiac impulse from the sinus node to all atria. The sensation at the same time is interruptions or fading of the heart, short-term dizziness, general weakness.

Features of the disease

Sinoauricular blockade is one of the varieties of sick sinus syndrome. When this occurs, the blocking of the conduction of an electrical impulse between the atria and the sinus node. This disorder is characterized by temporary atrial asystole and prolapse of one or more ventricular complexes.

Sinoauricular blockade is rare, and if it develops, it is most often in men (65%). The disease can be detected at any age.

ICD disease code: 144.0-144.2.

The next section will tell you what a sinoauricular blockade of 1, 2, 3 degrees and type is.

Degrees and types of sinoauricular blockade

Sinoauricular blockade is 1st, 2nd and 3rd degree.

• 1st degree is difficult to identify on the electrocardiogram. At the same time, cardiac impulses originate less often than necessary and completely reach the atria. may indicate sinoauricular block.
• The 2nd degree can already be seen on the ECG. Not all impulses reach the atria and ventricles. On the cardiogram, this is revealed by the appearance of the Samoilov-Wenkerbach periods. With the loss of one cardiac cycle, the increased R-R interval is equal to two main R-R intervals. Sometimes there is a blocking of every 2nd impulse that follows a normal contraction. This is a 2:1 sinoauricular block. In such cases, one speaks of allorhythmia.
• 3rd degree sinoauricular blockade is the blocking of all impulses from the sinus node. This can lead to asystole and death of the patient. The role of the driver is assumed by the atrioventricular node, the conducting systems of the ventricles or atria.

Causes

The main reasons for the development of sinoauricular blockade include:

• organic damage to the myocardium;
• increased tone vagus nerve;
• damage to the sinus node itself.

The disease most often occurs in patients with:

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Sinoauricular blockade can also develop due to:

• intoxication with adrenergic blockers, cardiac glycosides, drugs K, quinidine;
• performing defibrillation;
• with a reflex-increased tone of the vagus nerve.

Symptoms

Sinoauricular blockade of the 1st degree does not manifest itself in any way. Auscultation can reveal the absence of a subsequent cardiac contraction after two or three normal cycles.

The clinical manifestations of the 2nd degree block will depend on the frequency of the sinus impulse dropouts. With infrequent loss of heart contractions, the patient may experience:

• dizziness;
• chest discomfort;
• general weakness;
• dyspnea.

The symptomatology of sinoauricular blockade, characterized by the absence of several cycles of heart contractions, looks like this:

• feeling of a sinking heart;
• noise in ears;
• severe bradycardia.

With sinoauricular blockade with organic lesion myocardium, formation occurs.

As a result of developed asystole, patients may develop Morgagni-Edems-Stokes syndrome. Such a violation is characterized by pallor of the skin, unexpected dizziness, flickering of "flies" before the eyes, convulsions, loss of consciousness, ringing in the ears.

Diagnostics

The main methods of examination:

• electrocardiography, (ECG) signs of sinoauricular blockade are clearly visible on it;
• Ultrasound of the heart.

After electrocardiography, sinoauricular blockade should be distinguished from sinus bradycardia and, 2nd degree.

In case of confirmation of sinus bradycardia, tests are carried out with the introduction of atropine. After it, patients have a rate heart rate increases by 2 times, then sharply decreases by 2 times. There is a blockade. In the case of normal functioning of the sinus node, the rhythm will gradually increase.

Treatment

Sinoauricular blockade of the 1st degree does not require any treatment. Treatment of the underlying disease or refusal to take drugs that contribute to the disorder helps restore normal cardiac conduction.

• With a blockade that has developed due to vagotonia, the use of subcutaneous or intravenous atropine is effective.
• To stimulate the automatism of the sinus node, sympathomimetic drugs are used. These are ephedrine, alupten, isadrin.
• To improve the metabolism of the heart muscle, prescribe cocarboxylase, ribaxin, ATP. An overdose of these drugs may cause headache, nausea, insomnia, twitching of limbs, vomiting.

Patients are contraindicated to take cardiac glycosides, beta-blockers, antiarrhythmic drugs of the quinidine series, K salts, cordarone, rauwolfia preparations.

If sinoauricular blockade significantly worsens the patient's health, asystole attacks occur, doctors install a pacemaker temporarily or permanently to stimulate the atria.

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Prevention

Due to the insufficiently studied disease such as sinoauricular blockade, prevention as such does not exist. The main thing to do is to eliminate the causes of cardiac conduction disorders and be constantly monitored by a cardiologist (arrhythmologist).

Complications

The negative consequences of sinoauricular blockade are due to a slow rhythm due to organic damage to the heart. Usually the disease generates or aggravates, contributes to the development of ectopic and ventricular arrhythmias.

Forecast

How the sinoauricular blockade will manifest itself in the future will depend entirely on the underlying disease. The degree of conduction and the presence of other pathologies of the rhythm are also of great importance.

• The disease, which does not manifest itself in any way, basically does not cause any disturbances in hemodynamics.
• In the case of the development of Morgagni-Adams-Stokes syndrome, the prognosis is usually unfavorable.

Second-degree atrioventricular (AV) block

Second-degree atrioventricular (AV) block is characterized by impaired, delayed, or interrupted conduction of impulses through the AV node, with the exception of block. associated with premature atrial contraction. AV blockade can be permanent or temporary, depending on the features of anatomical or functional disorders in the conduction system. which are subdivided into type I blockade, or Mobitz type I and Wenckebach blockade - Mobitz type II blockade, 2: 1 blockade and complete AV blockade.

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

Of course, 2:1 AV block cannot be classified as either type I or II because only one PR interval is used for diagnosis. Both 2:1 block and block involving two or more sinus P waves are sometimes referred to as complete AV block, in which there is some conduction in the block, as opposed to third-degree AV block.

Pathophysiology

Type I AV block is most often the result of an abnormal conduction in the AV node, but can rarely be associated with infranodal block and is rarely secondary to structural anomalies 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 vagal-mediated and may occur in conditions accompanied by a relatively high tone of the parasympathetic nervous system, for example, in well-trained athletes, with an overdose of cardiac glycosides (eg, digoxin) and neurogenic (or neurotransmitter) syncope syndrome.

Vagal-mediated AV block occurs at the node when, under the influence of parasympathetic influences, a marked ECG slowdown is observed. sinus rhythm. Vagal-mediated AV block improves physical performance and occurs more frequently during sleep, when parasympathetic tone is dominant. If an increase in the tone of the sympathetic system (for example, physical exercises) initiates or exacerbates type I AV block, infranodal block may be suggested.

Cardioactive drugs are another common cause of AV block. They can have a negative (i.e. dromotropic) effect on the AV node directly, indirectly through the autonomic nervous system or in their combination. 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 blockade may be associated with a conduction disorder localized in the bundle of His, its distal sections. In this situation, the QRS complex may be wide, and the basal PR interval preceding the block is usually shorter, with reduced amplitude. The prognosis for type I infranodal block is significantly worse than for block at the level of the AV node. The location of the focus of type II blockade is most often infranodal, which determines the increased risk for the patient.

Distribution frequency in the USA

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

Mortality / morbidity

The location of the focus of the blockade and its root causes determine the prognosis. Nodal-level AV block and the vast majority of type I block have a favorable prognosis, while both types of infranodal block 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 is often non-progressive and benign in terms of mortality. The risk of progression to complete heart block is significant when the block is located in the His-Purkinje system (infranodal location).
• Type II AV block often progresses to third degree block and thus has a more worrying prognosis. Type II blockade can lead to Stokes-Adams syncope.
• Vagal-mediated AV block is generally benign in terms of mortality. but can lead to dizziness and fainting.

Gender specificity

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

Clinical manifestations

Symptoms associated with type I blockade vary greatly, ranging from asymptomatic course in well-trained athletes and individuals without significant structural changes in the heart, to periodic syncope, pre-syncope and bradycardia in patients with heart disease. AV block can cause cardiac arrest and angina pectoris.

The reasons

Second-degree AV block may occur with or without structural heart disease.

• An increase in vagal tone may be due to pain, mechanical stress on the carotid sinus, or carotid sinus hypersensitivity, which may result in slow sinus rhythm and/or AV block. Thus, vagal-mediated AV block can be confirmed by the slowing of the sinus rhythm noted by the ECG. High vagal tone can be seen in athletes and young people at rest. Type I Mobitz blockade has been described in 2-10% of distance runners observed.1
• Cardioactive drugs 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 seen as the cause 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 His-Purkinje block. Sustained AV blockade has been reported following adenosine infusion during a stress test in patients taking cardioactive medications, suggesting an underlying conduction disorder in addition to drug influence as the etiology of the blockade. Toxic levels of some other pharmacological agents, such as tricyclic antidepressants and lithium salts, may be accompanied by AV blockade. Presynaptic alpha agonists, adrenergics (eg, clonidine) may also cause or exacerbate 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, rheumatic fever, Sokolsky-Bujo disease)

• Infiltrative diseases:

• Amyloidosis
• Hemochromatosis
• Sarcoidosis, and abnormal 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

• Collagenosis with vascular lesions

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

• Other diseases accompanied by AV blockade

• Tumors of the heart
• Injuries (including those associated with catheterization, especially with an existing blockade of the left bundle branch block)
• Muscular "bridges" of the myocardium 7
• Transcoronary alcohol ablation of the interventricular septum in obstructive hypertrophic cardiomyopathy
• Transcatheter occlusion of an atrial or ventricular septal defect 8, 9
• Heart surgery for congenital malformations, especially near the septum
• Progressive (age) idiopathic fibrosis cardiac skeleton
• Valvular complications 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 be carefully evaluated clinically and followed 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 blockade may have autosomal dominant traits and show a tendency to be inherited. Several mutations in the SCN5A gene have been associated with hereditary AV block. Various mutations in another gene have been reported in other dysrhythmias such as long QT syndrome or Brugada syndrome.

One of the pathologies of the myocardium, in which there are failures (slowdown or complete stop) of electrical conductivity is called sinoatrial blockade (SA blockade). Normally, the impulses go to the atria from the sinoatrial node, and in case of pathology, a violation occurs at one of the stages, causing abnormal contraction rhythms and disorganization of the organ.

SA blockade - a violation of conduction in the sinus node of the heart

It occurs in people of any age and gender in about 0.2 - 2% of cases. Of these, 65% are men, 35% are women. More often it has a secondary character (against the background of existing lesions of the heart muscle). It mainly occurs at the age of 50 years, sometimes against the background of congenital anomalies or excessive activity of the vagal nerve - younger.

What is sino-arterial blockade

Anatomically, an electric charge arises in the sinus node (right atrium), passes through the atrioventricular node to the legs of the His bundle - the heart chambers contract. If dysfunction occurs at some stage, then all conduction deteriorates. From the point of view of diagnosis, treatment and development of the disease, the most important stage is the CA blockade of the 2nd degree. It is easy to identify and not too late to start treatment.

The disease is similar in etymology and causes to sinus dysfunctions (eg, weakness of the sinus node). Most doctors consider blockade to be a type of SSA (sinus node weakness).

Sick sinus syndrome can also be one of the causes of heart failure.

It can develop against the background of existing problems (chronic ischemia, malformations, heart attack, myocarditis), excessive activity of the autonomic system (vagotonia), drug use (poisoning with calcium channel and adrenergic receptor blockers, Digoxin and Quiindin, organophosphorus compounds). The first group accounts for 60% of cases, the second - 20%.

In addition, a negative factor that started the process can be: rheumatism, cardiosclerosis, tumors and leukemia, neglected hypertension, pathologies of the nervous system, inflammatory processes and infections (meningitis, encephalitis), brain injuries and chest, conducted resuscitation and defibrillation, endocrine system disorders, hereditary gene.

One way or another, the pathology is based on deformation, degeneration or inflammation of the sinoatrial node and nearby tissues.

Cardiosclerosis can provoke the development of pathology

Deviation classification

The main classification is based on the degree of progression of the disease: I degree (slowdown) and II degree (incomplete), which is divided into two types (moderate (Wenckebach) and high degree (Mebitsa), complete (III degree). Possible changes on the ECG are shown in the table .

Grade 3 is the most dangerous: not only the ventricles, but also the atria suffer. The second (partial blockade) is the most common.

One of the causes of blockade may be dysfunction of the sinus node

There is another classification (due to the blockade):

• node dysfunction;
• weak impulse;
• complete or partial immunity of the atrial muscles to impulses.

Symptoms of the disease

Sinoauricular blockade is distinguished by symptoms that depend on the stage of development of the pathology.

At 2 stages:

• dizziness and fainting, noticeable interruptions in the work of the heart;
• dyspnea;

Many patients with this pathology feel discomfort in the chest.

• arrhythmia and bradycardia;
• general weakness.

At 3 steps:

• no symptoms;
• noise in ears;
• fainting;
• heart failure (edema, cyanosis);
• impaired consciousness syndrome: pallor, hypotension, convulsions, ripples before the eyes;
• sudden death.

SA blockade of the 1st degree is mostly asymptomatic.

The presence of SA blockade can be detected on the ECG

From the inside, the pathology is determined when arrhythmia (violation of time intervals) and bradycardia (decrease in heart rate up to 30 beats) of the sinus, extrasystole (a type of arrhythmias) of the atria is detected on the ECG.

Possible consequences

The prognosis and risks depend on the course of the disease, the cause, the stage of development, and the characteristics of the patient. The safest first stage: does not cause metabolic (blood and oxygen supply) disorders and dysfunctions. The third stage bears the maximum danger in the form of a syndrome of disturbed consciousness and death. It also most often develops a pronounced asystole (cardiac arrest).

The second one is most susceptible to conservative treatment and, in combination with prevention, has a favorable prognosis. However, CA blockade of the 2nd degree of the 2nd type in advanced cases is fraught with an increase in episodes of heart failure, oxygen starvation and clinical death.

Blockade on the background of ischemia, one of the most difficult cases

The most unfavorable type is blockade due to ischemia. Elderly people are more susceptible. Partial but permanent blockades in this case, even with treatment, as a rule, they go into full and end in death.

Diagnostic methods

Sinoatrial blockade is diagnosed on the ECG (electrocardiogram). However, the first stage cannot be defined in this way. Only a slightly abnormal heartbeat (less often than normal), that is, a low pulse, can give it away. The only way is auscultation (listening).

At stages 2 and 3, the electrocardiogram shows a number of specific changes. Sinoatrial blockade of the 2nd degree: loss of one or more cycles. At the same time, with type 1, there is a shortening of the P-P interval with a final pause (shorter than the square of the P-P interval) due to an overdue blockade. Gradually, equal intervals are established, showing on the cardiogram the loss of the P wave and the QRS complex. With type 2 - sharp and prolonged pauses (long interval) against the background of normal equal P-P intervals. It can be related as 2:1 or 3:1, sometimes - 5:1 (far gone).

One of the diagnostic options is to record ECG values ​​for 72 hours.

At stage 3, the ECG shows a slow replacement rhythm. Electrophysiological methods help to more accurately determine the pathology.

Diagnostic methods also include:

• Daily ECG monitoring. Lasts at least 72 hours. Allows you to record the slightest fluctuations and changes in the rhythm of the heart at any time. It is used for negative ECG results, but the remaining suspicion of the presence of sinoatrial blockade.
• atropine test. A drug is introduced into the body (1 gram of a 0.1% solution), which causes the heartbeat to double (subject to the presence of the disease), and then it decreases by the same amount, ending with a blockade. The second degree (when the work of the sinus node is still preserved) is characterized by a gradual increase. Before the introduction of the drug and after the initial and control ECG, respectively.
• Additionally, ultrasound is used. With it, you can determine heart defects and other inflammations, muscle sizes and features (scars).

You also need to do an ultrasound of the heart.

Methods of treatment

Blockade of the first stage is practically harmless, but requires constant monitoring. Sinoauricular blockade of the 2nd degree of the 2nd type and 1, as well as the 3rd degree - treatment. In the presence of primary pathology, impaired hemodynamics - anticholinergics (Atropine, Saracin, Metacin, Platifillin), sympathomimetics (Ephedrine, Isoprenaline, Orciprenaline) and nitrates (Olikard, Monizol, Erinit, Nitroglycerin), partial pacing.

To improve metabolism in the heart muscle - adrenomimetics (Inosine, Cocarboxylase, Isadrin, Mezaton). Diuretic and hormonal therapy is used.

In case of persistent blockade or worsening of the condition with conservative treatment (pulse below 40, severe depression of consciousness, constant fainting and other signs of heart failure, clinical death) - the installation of a pacemaker.

Mezaton improves metabolism in the heart, alleviating the condition

If the blockade arose against the background of taking medications, then their urgent cancellation and maintenance therapy, detoxification of the body are necessary. Temporary electrical stimulation is acceptable, as in myocardial infarction.

When there is a sharp, but unexpected acute blockade- carrying out resuscitation: indirect massage heart and pulmonary ventilation, temporary pacing, injection of Atropine and (or) Adrenaline.

It is forbidden to use group β adrenoblockers, glycosides and antiarrhythmic quinidine drugs!

In addition, some of the permitted drugs have many adverse reactions and the risk of individual intolerance to the components that cause ectopic arrhythmia. Therefore, they require strict medical supervision!

Not all medicines can be used, so do not take anything without a doctor's prescription

Prevention of pathology

Specific instructions in medicine have not been identified, a list of general recommendations has been defined: regular examination by a cardiologist (once a year or six months), elimination of negative factors (bad habits and production, overload) and possible causes (obesity, sleep disturbances and daily routine), high-quality treatment existing diseases (hypertension, arrhythmia), regular courses of fortification of the body (alternate mineral complexes).

It is very harmful to eat a lot of salt

SA blockade 2 degrees 2 and 1 type involves prevention in order to obtain remission. To do this, it is necessary to know exactly the root cause so that preventive drug courses can be used. Otherwise, only general recommendations can be applied, but their effectiveness is much lower.

Heart block at night, from this video you will learn the main causes and methods of treatment:

Dizziness, pain in the region of the heart (shoulder blades). holter (sa-blockade 2nd degree type 2) Holter monitoring (sa-blockade 2nd degree type 2) Hello! I am 20 years old. There was pain in the region of the heart, it has been going on for 3 weeks, dizziness is frequent, the heart seems to stop before going to bed, a feeling of fear of death (I measure blood pressure and pulse endlessly), it can be very scary ), ultrasound of the heart is normal, gastroscopy (superficial focal reflux gastritis, moderate Bulbit, pyloritis, moderate reflux esophagitis); blood tests from a vein and a finger in tolerances, a urine test too, hormones are normal, thyroid normal, chest (ultrasound) normal, ultrasound internal organs in perfect order, fluorography (lungs and heart unchanged) They said to do a holter. Here is what is written in the conclusion: During the entire observation period, predominantly sinus rhythm was recorded (92.8%), which was interrupted by sinus arrhythmia. Average heart rate 86 bpm, minimum 49 (sleep), maximum 156 (climbing stairs) Predominantly negative bradycardia is observed during the entire observation period lasting 4h46m: in the active period 13 minutes, in the passive period - 4h33m The circadian index is 1.60, which indicates a significant decrease heart rate at night. Conduction disturbance: no pauses lasting more than 2000 ms were detected. Pauses 2 r-r were detected due to SA-blockade of the 2nd degree (9 in total). Maximum r-r the interval is 1620ms (SA-blockade 2 DEGREE 2 TYPE). Single complex sinus complex with aberration (transient blockade of PVLnPG). The PQ interval is 176ms within the normal range. Supraventricular arrhythmias - not detected Ventricular arrhythmias: detected 3 ventricular extrasystoles, including intercalary, of which 3 were isolated. ST segment elevation was detected with a duration of 1172 (85%) in the lead channel A, B. The maximum elevation is 349 μV (early ventricular repolarization syndrome) Analysis of the QT interval: at maximum heart rate it is 286 ms, at the minimum is 408ms. The average for the entire observation period is 347ms.

Mild sinoauricular conduction disturbances are usually transient, cause cardiac cycle loss, and are not life-threatening. But any pathological changes conduction in the area of ​​the sinus node (SA blockade) require a complete 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:

1. complete absence of momentum in the node;
2. low force of impulse action;
3. limitation of conduction between the node and the atrium.

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

• pathology of the heart (cardiomyopathy, myocarditis, myocardial infarction, congenital malformations, chronic heart failure, atherosclerosis);
• negative drug effects (side effects of certain cardiovascular drugs);
• toxic damage in case of poisoning or serious illness (pronounced 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 complete diagnosis, highlighting the severity and type of cardiac pathology, which will become the basis of high-quality treatment.

Options for pathology

There are 3 levels of severity:

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

With the help of electrocardiography, the doctor will be able to identify a variant of a 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, except for a moderate slowing of the heartbeat. Possible manifestations of blockade of the sinus node of the 2nd degree include:

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

At grades 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 taken.

Diagnostic studies

In addition to the usual examination, the doctor will definitely refer you to an ECG. It is according to the results of an electrocardiographic study that one can accurately identify the presence and severity of sinoatrial blockade. At grade 1 ECG, the manifestations are minimal - sinus bradycardia, which normally occurs in many people and is not considered a pathology.

The first type of 2nd degree of blockade on the cardiogram is expressed by periodic rhythmic loss of cardiac cycles (loss of P-P teeth or the whole PQRST complex). The second type is characterized by non-rhythmic and repeated loss of P-P waves, PQRST complexes, when two or more cardiac cycles disappear, forming pathological condition 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 high risk sudden death.

Principles of treatment

Detection of sinus bradycardia does not require therapeutic measures: it is enough to periodically see a doctor. In case of violation of conductivity of the 2nd degree, it is necessary to carry out complex therapy:

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

Indications for the installation of a pacemaker are:

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

In grade 2-3 sinoatrial block, the best response to 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 due to 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 disorders of cerebral blood flow;
• complete asystole of the heart;
• sudden death.

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

A deterioration in cardiac conduction detected in time can be corrected with a pacemaker and drug therapy, and with the development of severe complications, it is extremely difficult to restore lost heart functions and restore the previous quality of human life.

Sinoatrial blockade - Rhythm and conduction disorders of the heart

10. CONDUCTION DISORDERS OF THE HEART

10.1. Sinoatrial blockade

This is a violation of the passage of the sinus impulse through the sinoatrial junction. Sypoatrial (SA) blockade is divided into the following types:

full (or III degree).

sinoatrial blockade occurs in 0.16-2.4% of people, more often after 50-60 years and slightly more often in women than in men.

Etiology. sinoatrial blockade more often (35-61%) occurs with coronary artery disease, especially with damage to the right coronary artery and subsequent posterior myocardial infarction. It can appear (in 6-20% of patients) with acute myocarditis various etiologies or myocarditic cardiosclerosis, with hypertension, side effect drugs (cardiac glycosides, quinidine, beta-blockers, cordarone), hyperkalemia, and also due to increased tone of the vagus nerve of peripheral (reflex tests, hypersensitivity of the carotid sinus) or central (tumors, inflammation or vascular pathology of the brain) origin. Less commonly, SA blockade occurs with congenital cardiomegaly, thyroid dysfunction, mitral and aortic valves, in the first 5-10 days after electropulse therapy. sinoatrial blockade can also be congenital, inherited in an autosomal dominant way. In 25-50% of cases, no obvious pathology of the myocardium can be detected. At autopsy, pronounced fibrosis of the SA junction and SU is usually found, as well as various changes in other parts of the conduction system of the heart and in the myocardium.

The clinical picture depends on the form of SA blockade. sinoatrial block I degree does not cause any complaints; with II-degree blockade, dizziness, a feeling of irregular heart activity, or even fainting (with advanced SA blockade) may occur; with blockade of the III degree, if the AV connection becomes the pacemaker, patients may not feel a rhythm disturbance. If the jumping rhythm of the AV connection does not occur, then with a short

SA blockade of the III degree may cause fainting, and with prolonged - sudden death.

Sinoatrial blockade of the 1st degree does not cause objective changes in cardiac activity. In the case of sinoatrial blockade of the II degree, an arrhythmia is observed that is similar to extrasystole (with a block of only single impulses), or severe bradycardia (if every second impulse is blocked).

On the ECG with CA blockade of the 1st degree: all SU impulses pass through the CA junction, but at a slower pace. The normal duration of SA conduction, established during an electrophysiological study, reaches 0.04 - 0.153 (0.092 ± 0.06) s. Due to the fact that the distribution of the sinus impulse in the SA junction is not reflected in the normal ECG, this blockade cannot be diagnosed according to the ECG data; it can only be diagnosed if it is associated with a type II second-degree SA block. Then the P-P interval between two sinus impulses, covering the blocking site, is not equal to the P-P interval of two normal sinus impulses, but is shorter than this interval. With simultaneous SA II degree blockade due to blocking of one sinus impulse, conductivity in the SA junction temporarily improves, and therefore this shortening of the RR interval occurs.

sinoatrial block II degree. Sinus pulses sometimes do not pass through the CA connection. There are 3 types of this blockade: I, II and far-reaching blockade.

In type I, the conductivity in the SA compound gradually worsens and completely disappears (Wenckebach phenomenon). On the ECG: 1) a pause in the RR of the sinoatrial blockade is preceded by a progressive shortening of the RR intervals of the sinus rhythm. The shortening of the PP interval is due to the fact that with a gradual deterioration in conductivity in the CA compound, the deceleration rate gradually decreases; 2) the RR pause of the sinoatrial blockade is less than twice the duration of the previous normal RR interval. The RR interval after the pause is longer than the RR interval before the pause. The conduction coefficient is different - 3:2, 4:3, etc. (Fig. 37, A). Type I blockade is differentiated from sinus arrhythmia and atrial, especially blocked, extrasystoles. With sinus arrhythmia, the duration of the RR intervals varies depending on the breathing cycles (when exhaling, the RR interval is lengthened, while inhaling, it is shortened). With conducted or blocked atrial extrasystoles, there are always P waves of a different configuration than normal sinus P waves. They are difficult to notice if they are superimposed on the ST segment or T wave. A conduction ratio of 3: 2 is sometimes difficult to distinguish from sinus extrasystole.

Rice. 37. Sinoatrial block II degree. A - type I; B - II type.

In SA type II blockade, conduction in the SA junction disappears without gradual deterioration, and a single P wave with a QRS complex is observed on the ECG. The R-R pause will be equal to twice the normal interval (Fig. 37, B). Type II block with a ratio of 2:1 must be differentiated from sinus bradycardia. The number of heartbeats in sinus bradycardia is 40-60 in 1 min, with type II SA blockade - 30-40 in 1 min. Tests with physical activity or atropine. With sinus bradycardia, the heart rate increases gradually, with SA blockade of 2: 1, it immediately doubles.

With far-reaching SA blockade, 2-3 or more sinus impulses fall out at once. The R-R pause will be equal to the value of 2-3, etc., of the normal R-R intervals.

With complete SA blockade, all SA impulses are blocked and do not enter the atria. Then, most often, a jumping ectopic rhythm occurs from the atria, less often from the AV junction, or even more rarely from the ventricles. The ECG often shows retrograde P waves.

Transient 3rd-degree SA block or far-reaching 2nd-degree SA block must be differentiated from a temporary arrest of the sinus node or the phenomenon of sinoventricular conduction (the sinus impulse enters the ventricles through the internodal atrial bundles).

When the SS is temporarily stopped, the extended P-P interval does not have a definite mathematical relationship to the normal P-P intervals. In addition, 3rd degree sinoatrial blockade is often recorded in conjunction with periods of 2nd degree sinoatrial blockade. Cardiac asystole due to SA block usually results in atrial complexes or an atrial ectopic rhythm. With a temporary stop of the sinus node and a joint depression of atrial activity, atrial contractions are rarely detected. In these cases, after a period of cardiac asystole, a sinus or AV impulse is usually recorded.

In the case of the phenomenon of sinoventricular conduction, there are no retrograde conducted P waves and ectopic atrial waves.

Together with sinoatrial blockade, various disorders of AV or intraventricular conduction are often recorded. In patients with SA blockade, more often than others, various cardiac arrhythmias occur (supraventricular tachycardia, atrial fibrillation or flutter, atrial extrasystole, less often - ventricular extrasystole and tachycardia).

Treatment.

Treatment options depend on the underlying disease and clinical course sinoatrial blockade. Short-term partial blockade resolves without treatment; if its occurrence is due to medicines you need to stop taking them. If increased vagal tone contributes to the appearance of frequently recurring SA blockade, atropine (as a parasymtolytic) or sympathomimetics (ephedrine, isoprenaline, orciprepalin) can be administered. When repeated attacks of loss of consciousness or episodes of clinical death appear against the background of SA blockade, it is necessary to apply cardiac ES: in acute organic diseases heart (for example, myocarditis) or with an overdose of drugs - temporary, and with fibrotic changes in the heart and advanced age of patients - permanent. In such cases, medications usually do not help. Ventricular pacing should be used, as there are often concomitant cardiac conduction disorders. ES of the heart often prevents the occurrence of cardiac tachparythmias. sinoatrial block is 10-20% of the indications for cardiac ES.

The prognosis depends on the etiology, duration, type of sinoatrial block, the state of cardiac activity and the combination of cardiac arrhythmias. The overall prognosis for sinoatrial block is better than for AV conduction disorders.

Partial short-term sinoatrial blockade (on the background of acute myocardial infarction, toxic effects of cardiac glycosides or increased vagal tone) does not have any noticeable effect on the prognosis. Permanent partial sinoatrial blockade (due to fibrotic changes in the sinoatrial region), especially in older people with coronary artery disease, can go completely and cause attacks of loss of consciousness and even sudden death.

Sinoatrial heart block

Rapid heartbeat - very dangerous symptom! Tachycardia can lead to heart attack

She can be defeated.

Diseases of the heart and blood vessels are very dangerous for the whole body. Oxygenated blood circulates throughout the body, washing and nourishing every cell of it. For the normal and well-coordinated work 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 - contractile - can be disrupted by various failures in the conduction of the myocardium - the heart muscle. One of these disorders is sinoatrial blockade, the details of the causes, symptoms and treatment of which in children and adults are discussed in the article.

What is sinoatrial blockade and what are its causes

sinoatrial node ( sinus node) is located in the wall of the right atrium somewhat lateral to the mouth of the superior vena cava, midway between its opening and the right auricle. The branches of the sinoatrial node (the bundles of Bachmann, Wenckebach, Torel) go to the myocardium of both atria and the atrioventricular junction. Violation of the passage of the sinus impulse through the sinoatrial node is called sinoatrial blockade, or sinoatrial blockade.

Experts note that sinoatrial blockade is nothing more than a type of SSS (weak 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 the prolapse 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 conducted to the atria and ventricles. Less commonly, there is a loss of 2-3 cycles, as a result of which a long pause is recorded during the examination, 3 times higher than normal intervals.

The disease is rare, occurring in about 0.16% of people. Most often it is diagnosed by ECG in people over 50 years old, and about 70% of them are males. Sometimes sinoatrial blockade is noted in children, in the vast majority of cases - with congenital or acquired at an early age organic pathology of the heart.

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 the posterior localization against the background of IHD. In 20% of people, pathology was diagnosed in connection with tolerated myocarditis of viral and bacterial etiology. Other possible reasons sinoatrial blockade:

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

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 blockade remain without an identified cause of development, but if the pathology ends in death, then autopsy shows fibrosis of the sinoanthricular junction and various disorders in other parts of the cardiac conduction system. Therefore, always the anatomical basis this disease are degenerative or inflammatory processes of the sinus node and tissues surrounding it.

Classification of pathology

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

1. Blocking the conduction of impulses from the sinus node to the atria.
2. Small force of impulses from the sinus node.
3. Complete absence of impulse production in the sinus node.
4. Poor susceptibility of the atrial myocardium to conduct electrical impulses.

Also, sinoatrial blockade is divided into the following degrees:

1. The first degree - there is an increase in the time of the impulse from the sinoatrial connection, but still this impulse reaches the atria, albeit with a delay. According to the ECG, this disease is not visible, it can only be determined with the help of EFA.
2. Second degree - there is a periodic violation of the conduction of the impulse to the atria, as a result of which ventricular complexes fall out, which is determined by the ECG. This degree of blockade is subdivided into two subtypes - sinoatrial blockade of the 2nd degree of type 1 (conduction disturbances develop gradually with the periodic complete disappearance of ventricular complexes) and type 2 (periods there is no excitation of the heart muscle without a previous increase in the time of sinoatrial conduction).
3. Third degree, or complete sinoatrial block. The impulse from the sinus node does not reach the atria at all, while asystole continues until the pacemaker of the 2nd or 3rd order is activated.

Symptoms of manifestation

With sinoatrial blockade of the 1st degree, which is called partial (incomplete), the patient does not make any complaints, so it can only be detected when conducting 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 frequency of the rhythm, the adaptation of a particular organism to slowing rhythms (bradycardia).

Second degree sinoatrial blockade causes disturbances cerebral circulation. Clinically, this manifests itself in the form of regular dizziness, sometimes leading to fainting, weakness, a drop in performance, a feeling of a slowing of the heart or the absence of its beating at some point. Symptoms can develop according to the type of extrasystole, if only single impulses are blocked in the patient, and also according to the type of bradycardia, if every 2nd impulse is blocked.

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

• syncope;
• unexpected, causeless failures (fainting);
• frequent dizziness;
• memory impairment;
• signs of heart failure - shortness of breath, suffocation, attacks of cardiac asthma, edema, an increase in the size of the liver.

Complications of sinoatrial blockade

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

In general, the prognosis even with complete sinoatrial block is considered to be better 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, concomitant arrhythmias and general condition heart health. The worst outcome is in the elderly, who suffer from constant partial blockade against the background of coronary artery disease, since it most often goes into a complete blockade and ends in cardiac arrest.

Diagnostic methods

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

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

For a more detailed study of the work of the heart and the diagnosis of sinoatrial blockade, many patients are recommended daily ECG monitoring, as well as transesophageal ECG (the latter is required to detect complete blockade). To clarify the cause of the pathology, ultrasound of the heart and other examinations are most often additionally performed according to indications. The differential diagnosis is made with sinus arrhythmia, atrial extrasystole, sinus bradycardia.

Treatment Methods

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

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

What Not to Do

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

Preventive measures

The hereditary form of the disease cannot be prevented. Lifetime acquired cases of sinoatrial blockade can be prevented by early correction and treatment of cardiac diseases and the exclusion of inappropriate drugs and their overdoses. You should regularly visit a cardiologist in the presence of coronary artery disease and lead a healthy lifestyle to exclude myocardial infarction. The control of hormonal levels, the state of the thyroid gland, blood vessels, the prevention of chest injuries are important tasks for the patient, which can also be attributed to measures of non-specific prevention of sinoatrial blockades.

Are you one of the millions with heart disease?

Have all your attempts to cure hypertension failed?

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

Sinoatrial blockade (SA): what is it, causes, symptoms, on the ECG, treatment

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

In a healthy heart, an electrical charge is generated in the sinus node, which is located in the thickness of the right atrium. From there it spreads to the atrioventricular node and to the legs of the bundle of His. Due to the successive passage of the impulse along the conductive fibers of the heart, the correct contraction of its chambers is achieved. If an obstacle arises in one of the sections, then the contraction will also be violated, 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 the ventricles is disrupted. At a certain moment, the heart "misses" the impulse it needs and does not contract at all.

Different degrees of sinoatrial blockade require a different therapeutic approach. This violation may not manifest itself at all, and 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, observation can be limited; blockade of 2-3 degrees requires appropriate treatment.

Causes of sinoatrial blockade

Among the main mechanisms of sinoauricular blockade are damage to the node itself, a violation of the propagation of an impulse through the heart muscle, and a change in the tone of the vagus nerve.

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

The factors leading to sinoauricular blockade are:

1. Heart defects;
2. Inflammatory changes in the heart (myocarditis);
3. Cardiovascular form of rheumatism;
4. Secondary damage to the tissues of the heart in leukemia and other neoplasms, injuries;
5. Ischemic heart disease (cardiosclerosis, post-infarction scar);
6. Myocardial necrosis (heart attack);
7. Cardiomyopathy;
8. Vagotonia;
9. Intoxication with drugs in excess of the permissible dose or individual intolerance - cardiac glycosides, verapamil, amiodarone, quinidine, beta-blockers;
10. Organophosphate poisoning.

The work of the SU is influenced by the activity of the vagus nerve, therefore, when it is activated, a violation of the generation of an impulse and the appearance of a SA blockade are possible. Usually, in this case, they talk about transient SA blockade, which itself appears and also disappears. Such a phenomenon is possible in practically healthy people, without anatomical changes in the heart itself. In isolated cases, idiopathic sinoauricular blockade is diagnosed, when the exact cause of the pathology cannot be found out.

In children, conduction disturbance from the sinoatrial node is also possible. Typically, such an arrhythmia is detected after the age of 7, and autonomic dysfunction becomes a common cause, that is, the blockade is more likely to be transient, against the background of an increase in the 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.

Varieties (types and degrees) of sinoatrial blockade

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

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

With blockade of the sinus node of the 1st degree, the node functions, and all impulses cause a contraction of the atrial myocardium, but this happens less often than normal. The impulse through the node passes more slowly, therefore, the heart contracts less often. It is impossible to fix such a degree of blockade on the ECG, but it is indirectly spoken of by the 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, is of two types:

• SA-blockade of the 2nd degree of the 1st type - 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 time of impulse conduction are called Samoilov-Wenckebach periods;
• SA-blockade of the 2nd degree of the 2nd type - the contraction of all parts of the heart drops out after a certain number of normal contractions, that is, without a periodic slowdown in the movement of the impulse along the SA node;

Sinoauricular blockade of the 3rd degree is complete, when there is no next contraction of the heart due to the absence 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 the ECG in 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 (a variable sign).

It is possible to speak reliably about the presence of SA-blockade according to the ECG, starting from the second degree of the disorder, in which there is no complete cardiac contraction, including the atria and ventricles.

On the ECG at 2 degrees are recorded:

1. Elongation of the interval between atrial contractions (R-R), and during the loss of one of the next contractions, this interval will be two or more normal;
2. Gradual decrease in RR time after pauses;
3. Absence of one of the regular PQRST complexes;
4. During long periods of absence of impulses, contractions generated from other sources of rhythm (atrioventricular node, bundle of His bundle) may occur;
5. If not one, but several contractions fall out at once, the duration of the pause will be equal to several R-R, as if they were normal.

Complete blockade of the sinoatrial node (3 degrees), 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, it is considered one of the most dangerous types of arrhythmia, when the patient is likely to die during asystole.

Manifestations and methods of diagnosis of SA-blockade

The symptomatology of sinoatrial blockade is determined by the severity of disorders in the conductive fibers of the heart. At the first degree, there are no signs of blockade, as well as patient complaints. With bradycardia, the body "gets used" to a rare pulse, so most patients do not experience any anxiety.

2nd and 3rd degree SA blocks are accompanied by tinnitus, dizziness, chest discomfort, and shortness of breath. Against the background of a decrease in the 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 with the appearance of edema, cyanosis of the skin, shortness of breath, decreased performance, and enlarged liver is possible.

In a child, the signs of SA-blockade differ little from those in adults. Often, parents pay attention to a decrease in efficiency and fatigue, blue nasolabial triangle, fainting in children. This is the reason for contacting a cardiologist.

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

syncope in MAC syndrome due to blockade of the sinus node

Suspicion of the presence of a blockade in the heart arises already during auscultation, in which the cardiologist fixes bradycardia or the loss of another contraction. To confirm the diagnosis of sinoauricular blockade, the main methods are electrocardiography and daily monitoring.

Holter monitoring can be carried out for 72 hours. Long-term monitoring of the ECG is important in those patients in whom, with a suspected arrhythmia, the usual cardiogram failed to detect changes. During the study, a transient blockade, an episode of SA-blockade at night or during exercise may be recorded.

Children also undergo Holter monitoring. Pauses lasting more than 3 seconds and bradycardia less than 40 beats per minute are considered diagnostically significant.

Indicative is the test with atropine. 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 pathology or search for the cause of the blockade, an ultrasound of the heart can be performed, which will show a defect, structural changes in the myocardium, a scarring area, etc.

Treatment

SA-blockade of the 1st degree 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 stop drugs 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 the appointment of atropine and its drugs - bellataminal, amizil. The same drugs are used in pediatric practice for vagotonia, which causes a transient blockade of the sinus node.

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

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

With a fixed SA blockade, one should not take beta-blockers, cardiac glycosides, cordarone, amiodarone, potassium preparations, since they can cause even more difficulty in automatism of SU and aggravate bradycardia.

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

With a sudden severe blockade with attacks of Mrogany-Adams-Stokes, temporary pacing is necessary, indirect heart massage and artificial ventilation of the lungs are indicated, atropine and adrenaline are administered. In other words, a patient with such seizures may require full-fledged resuscitation.

If the exact causes of the development of sinoatrial blockade have not been established, there are no effective measures to prevent this phenomenon. Patients who already have ECG changes should correct them with medication prescribed by a cardiologist, normalize their lifestyle, and regularly visit a doctor and take an ECG.

Children with arrhythmias are often recommended to reduce the overall level of load, to reduce classes in sports sections and circles. Visiting children's institutions is not contraindicated, although there are experts who advise limiting the child in this as well. If there is no risk to life, and episodes of SA-blockade are rather isolated and transient, then it makes no sense to isolate the child from school or trips to Kindergarten, but observation in the clinic and regular examinations are necessary.

The danger of sinoauricular blockade and methods of its treatment

Sinoatrial or sinoauricular blockade is a form of heart rhythm disturbance. Impulses in the sinus node are generated, but do not propagate through the atria. As a result, the contraction of the heart does not occur. Clinically, this condition can be manifested by syncope and in some cases requires the installation of a pacemaker.

What is

The normal heartbeat is controlled by electrical signals that are regularly produced in the sinus node. This accumulation of special cells is located in the upper part of the right atrium. From there, the impulse propagates 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

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

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

Reasons for development

In young people, this conduction disorder may be associated with increased excitability of the vagus nerve and the predominance of the parasympathetic system. During daily ECG monitoring, they have pauses, usually during sleep. This condition is not life threatening, but may limit a young person's professional fitness.

Extracardiac causes of pathology:

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

• brain tumor;

• intracranial hypertension (increased CSF pressure in the cavities of the ventricles of the brain);

• hypothyroidism (insufficient production of thyroid hormones);

• progressive liver disease (hepatitis or cirrhosis);

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

SA blockade can cause heart disease:

• ischemic cardiomyopathy caused by coronary artery 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 (SSS). The disease is accompanied by a violation of the production of normal impulses, slow heartbeat, tachycardia attacks and the formation of long pauses.

Sinoauricular blockade can be caused by an overdose of such medicines:

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

Degrees of manifestation and their features

Sinoatrial blockade of the 1st degree - a delay in the output of an electrical signal. In this case, the time required for the propagation of excitation to the atria increases. At this stage, sinoauricular blockade on the ECG does not appear. It can only be diagnosed using an electrophysiological study (EPS).

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

Sinoauricular blockade of the 3rd degree is characterized by the absence of several sinus impulses. A long pause is recorded on the ECG, 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 per minute.

If the replacement rhythm is not formed, the work of the heart stops. The brain lacks oxygen. This is accompanied by loss of consciousness.

For information on how sinoatrial blockade looks on the ECG and the mechanism of its development, see this video:

Symptoms of pathology

SA-blockade of the 1st degree has no clinical manifestations.

Sinoauricular blockade of the 2nd degree is usually well tolerated by the patient. Sometimes the patient complains of a feeling of interruption, heart failure, slight dizziness. Clinical symptoms associated predominantly 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 on the implantation of a pacemaker to the patient.

Diagnostics

On the ECG taken at rest, it is possible to register manifestations of SA-blockade of the 2nd and 3rd degree.

Sinoauricular blockade of the 2nd degree of the 1st type is associated with a gradual slowdown in the output of the impulse from the sinus node. On the cardiogram, there is 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.

Type 2 sinoauricular block is caused by a sudden blockage in the output of an electrical signal. There is a pause equal to twice the interval between adjacent P waves. If a 2: 1 block 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 blockade of the 2nd degree of the 1st type; b) Sinoauricular blockade of the 2nd degree, type 2; c) Complete SA blockade

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

Treatment of pathology

SA-blockade of 1 and 2 degrees does not require treatment. The disease that caused the conduction disorder is being treated.

Treatment of sinoauricular blockade of the 3rd degree includes 3 stages:

With a sudden onset of SA-blockade, atropine is used. This medicine inhibits the activity of the parasympathetic nervous system, speeds up the heartbeat, increases the efficiency of blood circulation. Ephedrine and norepinephrine stimulate the sympathetic nervous system, speeding up the heartbeat and improving blood flow. These medicines are used only as emergency measures.

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

Forecast

By itself, SA-blockade practically does not cause serious complications. Dangerous SSSU, of which it is a part. With this disease, there may be:

Implantation of 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.).

Read more about atrioventricular block here.

Prevention

Sinoatrial blockade is not a disease, but only a syndrome that complicates the course of various diseases. Therefore, its prevention is reduced to the elimination of risk factors for cardiovascular pathology (smoking, overweight, inactivity, increased blood pressure).

Non-cardiac diseases that can cause this arrhythmia should be treated in time, as well as self-treatment with antiarrhythmic drugs should be abandoned.

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

SA block 2nd degree type 1

Sinoatrial blockade is a pathology of the conduction system of the heart, characterized by a violation of the impulse from the sinus node to the atria.

The cause of such a violation of 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 connective tissue, intoxication with antiarrhythmic drugs (cardiac glycosides, B-blockers, etc.), myocarditis, myocardial dystrophy of metabolic-dystrophic genesis, 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 on the way from the sinus node to the right atrium

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

Clinical picture

Clinically, sinoatrial blockade of the 2nd degree manifests itself fainting spells(Morgagni-Adams-Stokes syndrome). Such syncope is characterized by the absence of convulsions and any aura, a feeling of cardiac arrest or a pronounced decrease in its rhythm; possible drop in blood pressure with cooling of the skin, cold sweat. Syncope can be provoked by a sharp turn of the head, coughing, wearing a tight collar. They mostly stop on their own, but in advanced cases, resuscitation may be necessary.

Also worried about a rare pulse, interruptions in the work of the heart, fainting with the appearance of tinnitus and severe weakness, nausea, shortness of breath when eating, muscle weakness.

The development of bradycardia is often accompanied by a progressive course of heart failure, coronary pathology, and dyscirculatory encephalopathy (memory lapses, irritability, insomnia, increased dizziness, paresis, "swallowing" 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. Physical examination reveals bradycardia, arrhythmic heartbeats, changes in blood pressure numbers.

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

Treatment

First of all, eliminate the cause that caused the sinoatrial blockade. All drugs that contribute to conduction disorders are canceled. With moderate bradycardia (beats per minute), teopec, eufillin, belloid are prescribed. In emergency cases (asystole, Morgagni-Adams-Stokes attack), resuscitation is carried out.

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

Forecast

The prognosis for sinoatrial blockade depends on the cause of the disease, clinical picture, age of the patient, comorbidities. Properly selected drug therapy, or the installation of a pacemaker improves the prognosis, improves the quality of life, but the absence of any treatment can cause Morgagni-Adams-Stokes attacks and sudden death. See also Type 2 SA block.