Sinoauricular block on ecg. Cardiac conduction disorders (AV block)

If there are disturbances in the functioning of the sinus node, new sources can form in various areas of the heart muscle. They provide electrical impulses.

The presented new sources may have a negative impact on the sinus node, competing with it or aggravating its activity.

There may be a blockage in the propagation of the wave through the heart muscle. All presented negative phenomena can be accompanied by arrhythmias and, in the worst case, blockades, which are called atrioventricular.

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Conducting cardiac system

Speaking about cardiac impulses, it should be noted that they are formed in the formation of the sinus node. It is located in the area of the right atrium and is the main one.

It is the sinus node that guarantees the frequency of rhythmic contractions, which are then transmitted to the atrioventricular node.

The latter is located in the area of the interatrial septum. The fibers that form the bundle of His lag behind it. It is located in the septum between the ventricles, from which both its legs emerge: right and left. The presented endings branch and terminate on the myocardial cells of the ventricles.

Each of the components of the conductive system can independently create excitation, and if the operation of a certain node located above is destabilized, its functioning will replace the underlying one.

However, in such a situation, the degree of impulse frequency suffers, and, as a result, the rhythm, which decreases significantly (from 60 to 20 contractions).

Causes of pathology

2nd degree heart block occurs due to the following factors:

genetic predisposition and inherited pathologies;
coronary heart disease and myocardial infarction;
, angina pectoris, myocarditis;
consuming large dosages of medicinal components or using medications not according to medical recommendations;
change in the thickness of the heart muscle.

The heart rate of an adult in normal health is 60 to 80 repetitions per 60 seconds. If no heart contractions are observed within 3-5 seconds, then the person is likely to lose consciousness. He may also begin to have convulsive contractions, and in the absence of specialist help, death occurs.

The presented pathological phenomena occur occasionally or can be observed constantly. identified using an ECG.

Differences between 2nd degree heart block

With 2nd degree heart block, not every impulse from the atria is conducted to the ventricular region, and therefore some contractions of the represented region are lost.

On the ECG, manifestations of deceleration or optimal complexes are identified first.

Only after this is a wave detected, which corresponds to the contraction of the precardiac region, and contraction of the ventricles is not observed. This can happen with every fifth, fourth, third and any subsequent contraction.

Blockades that form without a previous slowdown in implementation can transform into full-fledged heart block. Treatment when a 2nd degree blockade is detected largely depends on the underlying disease.

In some cases, atropine and isadrin are used. If the heart rate is significantly reduced, then permanent electrical stimulation of the heart is used, namely a pacemaker.

Treatment methods

When a blockade is formed due to pathologies of the heart (myocarditis or acute myocardial infarction), the leading disease is first dealt with.

The recovery algorithm for 2nd and 3rd degree blockages is selected taking into account where the disturbance is located within the conductivity:

If the blockade relates to a proximal tic	Treatment is carried out with drugs such as isadrin or the introduction of atropine under the skin. At the treatment stage, physical exercises are completely excluded. loads.
For distal blocking	Drug therapy does not guarantee the desired effect. The only treatment option is electrical stimulation of the heart muscle. When the blockade is acute and occurs as a result of myocardial infarction, intermittent stimulation is carried out due to electricity. With a stable blockade, the presented measure must be carried out continuously.
In case of unexpectedly developing absolute blockade	If stimulation is not possible, an Isuprelai or Euspiran tablet is placed under the patient’s tongue (in some cases, 0.5 tablets are used). For introduction into the vein, these drugs are dissolved in a composition with glucose (5%).
Absolute blockade of the heart muscle formed due to digitalis intoxication	Neutralized by eliminating glycosides. If the blockage, the rhythm of which does not exceed 40 beats within 60 seconds, persists even after stopping glycosides, Atropine is introduced into the vein. In addition, Unitol injections are injected into the muscles (up to 4 times during the day). If there is such a need (for medical reasons), then temporary electrical stimulation is performed.

Under the influence of medicinal components on the vagus nerve, situations are possible in which absolute blockage of the heart is transformed into partial.

Folk remedies

The use of folk recipes to restore health during heart blockade is also recommended to be agreed with a specialist. But first of all, you need to follow basic lifestyle recommendations.

It is necessary to exclude the use of alcohol and cigarettes, and minimize the use of strong coffee and tea. It is undesirable to consume salt, as well as fried and fatty foods.

For a speedy recovery, salty and smoked dishes are excluded from the menu, and preference is given to fruits, vegetables, meat and fish with a low fat content, as well as similar dairy products.

Traditional medicine can offer the following simple recipes that will help the heart muscle function fully:

Decoction of the root part of valerian	2 tsp. Dried finely chopped valerian root is poured into 100 ml of boiling water and boiled under the lid for 15 minutes. The product is cooled and filtered; it should be consumed three times a day, 1 tbsp. l. before meals.
Melissa decoction	To prepare it, use 1 tbsp. l. pour 400 ml of boiling water with a heap of lemon balm herb and let it cool until it cools 100%. After this, the product is filtered and taken 0.5 cups 3 times a day before eating. The presented mixture is in great demand among athletes.
Decoction from the flower part of hawthorn	1 tsp. The flowers of the plant are poured with 200 ml of boiling water and heated in a water bath for 15 minutes. The composition is cooled, filtered and diluted with water to 200 ml. Drink 0.5 cups 30 minutes before meals.

Mixing onions with an apple, for the preparation of which you need to mix 1 small head of regular onion. Next, grate 1 apple on a fine grater and mix the resulting mixture thoroughly. The mixture must be consumed 2 times in between meals.

Peppermint composition, for the preparation of which use 1 tbsp. l. finely chopped mint leaves, which are poured with 200 ml of boiling water. Infuse the mixture under the lid for at least 60 minutes. The decoction is filtered and consumed slowly over 24 hours.

It is necessary to avoid excessive physical and emotional stress, remember to adhere to a rest regime and carry out physical exercises as often as possible.

Consequences

The timing of disability is directly dependent on how difficult the leading disease is.

The prognosis depends on the underlying disease and the level of blockage. A pessimistic prognosis is associated with distal blockades, because they are prone to constant development - the consequences in this case will be the most severe.

Absolute heart block of the distal type is identified by the likelihood of fainting in 70% of cases. The blockade, which develops according to the proximal algorithm, is determined by the possibility of fainting in 25% of cases.

It should be noted that:

if a primary attack of Morgagni-Adams-Strokes occurs and an pacemaker is not transplanted, then life expectancy is significantly reduced and will be no more than 2.5 years;
the survival rate of patients increases due to permanent stimulation;
the prognosis after transplantation is directly dependent on the nature of the leading disease.

If myocardial infarction of the anterior wall occurs, then with absolute blockade there is aggravated damage to the septum between the ventricles. This means that the prognosis is extremely unfavorable: the mortality rate from ventricular fibrillation or cardiac failure is identified in 90% of cases.

2nd degree heart block is a dangerous pathology that can worsen a person’s life, causing many complications. In order to avoid this, you should undergo a correct and timely course of treatment.

People should not neglect folk recovery methods, which will enable a person to live on without encountering blockades. The essence of the phenomenon is partial or complete blockade of impulse transmission from the sinus node to the atrium. Causes of sinoatrial block (SAB): autonomic dysfunction with vagotonia, carotid sinus hypersensitivity syndrome, immaturity of the sinus node, hyperkalemia, drug intoxication, degenerative and inflammatory changes in the node, myocarditis, cardiomyopathies, etc. Diagnosis of SAB is carried out using an ECG study. There are SAB I, II, III degrees.

Sinoatrial block of the first degree (SAB I) occurs due to a slowdown in conduction in the perinodal region, loss of atrial contractions does not occur, and therefore it is almost impossible to make a diagnosis using a surface ECG.

Second degree sinoatrial block (II degree SAB) is a partial (incomplete) block of impulse conduction to the atrium.

There are two types of SAB II degree. 1st type - (Wenckebach periodical).

Sinoatrial block of the second degree, type 1 (Wenckebach period)
ECG criteria
Typical periodicals:
- loss of the P wave is preceded by a gradual shortening of the P-P intervals;

The first interval after the pause is longer than the P-P interval preceding the pause.

Atypical periodicals:
- loss of the P wave;

The loss of the P wave is preceded by a gradual increase in the P-P intervals.

Second degree sinoatrial block, type 2 (MOBITC type II)
ECG criteria:
- loss of the P wave;

The duration of the pause is equal to the sum of two R-R intervals or more (2:1; 3:1) with the previous normal rhythm.

During pauses in SAB of any degree, it is possible to detect impulses escaping from the atria, atrioventricular junction or ventricles.

Sinoatrial block can be combined with atrioventricular block, which indicates diffuse damage to the conduction system.

Third degree sinoatrial block is otherwise called “complete sinoatrial block”. With this blockade, there is no excitation of the heart from the sinus node, which is manifested by the absence of PQRST complexes on the ECG (asystole) and registration of the isoline. Asystole continues until the third-order driver begins to act (from the atria, atrioventricular junction or from the ventricles), which leads to the appearance of an ectopic replacement (escaping, slipping out) rhythm with the absence of a normal P-wave. The ECG often shows signs of retrograde atrial excitation.

Clinical manifestations of SA blockade depend on the heart rate and the degree of adaptation of the body to bradycardia. If with SA blockade of the first degree there are no clinical manifestations, then with SA blockade of the II-III degree, developing bradycardia leads to disruption of cerebral blood flow: syncope, instantaneous “lapses” of memory and episodes of dizziness. Manifestations of heart failure may occur in the form of shortness of breath, attacks of cardiac asthma, edema, and enlarged liver. The development of severe bradycardia (heart rate less than 40 per minute) often leads to Morgagni-Adams-Stokes (MAS) attacks in the form of episodes of loss of consciousness, which may be accompanied by muscle cramps, respiratory arrest, involuntary urination and defecation.

Treatment of children with SA blockade depends on its severity. With SA blockade? To a certain extent, therapeutic tactics are reduced to observation and treatment of the underlying disease. SA blockade of II-III degree requires more active intervention. Drug treatment is usually ineffective. A short-term unstable increase in rhythm can be achieved by prescribing anticholinergic drugs (atropine, platyphylline), combination drugs (bellaspona, belloid).

Sympathomimetic drugs (isadrin) are used, but they can contribute to the occurrence of ectopic arrhythmias and are often poorly tolerated by patients, so they are mainly used as emergency drugs for the development of threatening bradycardia with attacks of MAS. Treatment of an attack of MAS is carried out according to the rules of cardiopulmonary resuscitation using closed heart massage and artificial ventilation.

The presence of symptoms of cerebral blood flow insufficiency (syncope, Morgagni-Adams-Stokes syndrome), increasing signs of heart failure (shortness of breath, swelling, liver size, the appearance of attacks of cardiac asthma), a heart rate of less than 40 per minute are indications for surgical treatment - implantation of permanent electrocardiostimulator (ECS). The latter should be carried out only after assessing the state of atrioventricular conduction to decide on the mode of stimulation (atrial or ventricular).

If the conductive function of the atrioventricular junction is preserved (Wenckebach point above 120 pulses per minute), preference is given to atrial stimulation in the AAI mode. In this case, the physiological sequence of contraction of the heart chambers is preserved, which has a beneficial effect on the regulation of intracardiac, central and cerebral hemodynamics; ECS syndrome, which occurs as a result of a violation of the normal sequence of contraction of the heart chambers and is usually manifested by shortness of breath with low tolerance to physical activity, practically does not occur, weakness, dizziness, fainting. In case of atrioventricular conduction disturbance (Wenckebach point below 120 pulses per minute), implantation of a pacemaker operating in DDDR mode is indicated.

The prognosis depends on the etiology, duration, type of sinoatrial block, cardiac status and combination of cardiac arrhythmias.

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

What is sinoatrial block?

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

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

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

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

The main causes of pathology

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

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

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

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

First degree blockade and its features

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

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

Second degree blockade: brief description

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

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

What signs are accompanied by a 3rd degree blockade?

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

Drug treatment

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

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

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

First aid for blockade

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

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

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.

Sinoatrial block - Cardiac rhythm and conduction disorders

10. HEART CONDUCTION DISORDERS

10.1. Sinoatrial blockade

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

full (or III degree).

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

Etiology. sinoatrial block more often (35-61%) occurs with ischemic heart disease, especially with damage to the right coronary artery and subsequent posterior myocardial infarction. It may appear (in 6-20% of patients) with acute myocarditis of various etiologies or myocardial cardiosclerosis, with hypertension, side effects of drugs (cardiac glycosides, quinidine, beta-blockers, cordarone), hyperkalemia, and also due to increased tone of the peripheral vagus nerve (reflex tests, increased sensitivity of the carotid sinus) or central (tumors, inflammatory processes or vascular pathology of the brain) origin. Less commonly, SA blockade occurs with congenital cardiomegaly, thyroid dysfunction, mitral and aortic valve defects, in the first 5-10 days after electrical impulse therapy. sinoatrial block can also be congenital, inherited in an autosomal dominant manner. In 25-50% of cases, it is not possible to detect any obvious myocardial pathology. At autopsy, pronounced fibrosis of the SA junction and SU is usually found, as well as various changes in the remaining parts of the conduction system of the heart and in the myocardium.

The clinical picture depends on the form of SA blockade. 1st degree sinoatrial block does not cause any complaints; with second degree blockade, dizziness, a feeling of irregular heart activity, or even fainting (with advanced SA blockade) may occur; with third degree blockade, if the AV junction becomes the pacemaker, patients may not feel a rhythm disturbance. If the jump-up rhythm of the AV connection does not occur, then with a short

Third-degree SA blockade can lead to fainting, and if prolonged, sudden death.

Sinoatrial blockade of the first degree does not cause objective changes in cardiac activity. In the case of sinoatrial block of the second degree, an arrhythmia similar to extrasystole is observed (if only single impulses are blocked), or pronounced bradycardia (if every second impulse is blocked).

On the ECG with 1st degree SA block: all SA impulses pass through the SA junction, but slowly. 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 propagation of the sinus impulse in the SA junction is not reflected in a conventional ECG, it is impossible to diagnose this blockade using ECG data; it can only be diagnosed if it is combined with type II SA blockade of the second degree. Then the P-P interval between two sinus impulses, covering the place of blocking, is not equal to the P-P interval of two normal sinus impulses, but is shorter than this interval. With simultaneous second-degree SA blockade, due to the blocking of one sinus impulse, conduction in the SA junction temporarily improves, which is why this shortening of the P-P interval occurs.

sinoatrial block of the second degree. Sinus impulses do not pass through the SA junction at times. There are 3 types of this blockade: I, II and advanced blockade.

In type I, conductivity in the SA junction gradually deteriorates and completely disappears (Wenckebach phenomenon). On the ECG: 1) the P-P pause of sinoatrial block is preceded by a progressive shortening of the P-P intervals of sinus rhythm. The shortening of the P-P interval is due to the fact that with a gradual deterioration of conductivity in the SA junction, the deceleration rate gradually decreases; 2) the PR pause of the sinoatrial block is less than twice the duration of the previous normal PR interval. The P-P interval after the pause is longer than the P-P interval before the pause. The conduction ratio is different - 3:2, 4:3, etc. (Fig. 37, A). Type I block is differentiated from sinus arrhythmia and atrial, especially blocked, extrasystoles. With sinus arrhythmia, the duration of the P-P intervals varies depending on the breathing cycles (when exhaling, the P-P interval lengthens, when inhaling, it shortens). 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 extrasystoles.

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

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

With advanced SA blockade, 2-3 or more sinus impulses are lost at once. The R-R pause will be equal to the value of 2-3, etc., of 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 less often from the ventricles. Retrograde P waves are often observed on the ECG.

Transient third degree SA block or advanced second degree SA block must be differentiated from 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 control system is temporarily stopped, the extended R-R interval does not have a specific mathematical relationship to normal R-R intervals. In addition, third degree sinoatrial block is often recorded together with periods of second degree sinoatrial block. With cardiac asystole due to CA blockade, atrial complexes or atrial ectopic rhythm usually occur. With temporary arrest of the sinus node and 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 retrogradely 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, various heart rhythm disturbances (supraventricular tachycardia, atrial fibrillation or flutter, atrial extrasystole, and less often - ventricular extrasystole and tachycardia) occur more often than others.

Treatment.

Treatment tactics depend on the underlying disease and the clinical course of sinoatrial block. Short-term partial blockade resolves without treatment; if its occurrence is caused by medications, you must stop taking them. If the appearance of frequently repeated SA blockade is facilitated by increased vagal tone, atropine (as a parasymmatolytic) 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 case of acute organic heart diseases (for example, myocarditis) or in case of drug overdose - temporary, and in case of fibrotic changes in the heart and elderly patients - permanent. In such cases, medications usually do not help. Ventricular stimulation of the heart should be used, since there are often associated cardiac conduction disorders. Cardiac ES often prevents the occurrence of cardiac tachparrhythmias. sinoatrial blockade accounts for 10-20% of indications for cardiac ES.

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

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

Sinoatrial heart block

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

He can defeat her.

Diseases of the heart and blood vessels are very dangerous for the entire body. Oxygenated blood circulates throughout the body, washing and nourishing every cell. 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?

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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.

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.

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.

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?

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.

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

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

Diagnostic methods

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.

Treatment methods

What not to do

Preventive measures

Are you one of the millions who have heart disease?

Have all your attempts to cure hypertension been unsuccessful?

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

Sinoatrial (sinoauricular) blockade

Correct myocardial contractions are ensured primarily by the work of the cardiac conduction system.

When the production or transmission of nerve impulses along the fibers of these structures is disrupted, discoordination of cardiac activity develops. One of the types of arrhythmias is sinoatrial (SA) block.

Blockades are a pathological slowdown in the conduction of impulses along conductive pathways, up to the complete impossibility of transmission to other cells.

Among the main causes of such conditions are organic and functional changes caused by:

inflammation of the myocardium;
ischemia of the heart muscle;
drug intoxication;
vegetative dystonia;

Sinoatrial block corresponds to a disturbance in the conduction of electrical potential from the sinus node located at the level of the right atrium.

Impulse delay develops against the background of a high concentration of cardiac glycosides, β-blockers, cordarone, quinidine. SA blockade can be a consequence of an increase in the level of potassium in the blood of patients, vagotonia, thyroid dysfunction, and can also be congenital and inherited.

Types of pathology

Based on their temporary nature, all blockades, including SA, are divided into two types: transient and permanent.

Regarding the severity of SA blockades are classified as follows:

incomplete:
1st degree sinoatrial block;
SA blockade 2nd degree, first and second type;
advanced 2nd degree sinoauricular block;
complete sinoatrial block of the 3rd degree.

Manifestations of pathology are directly related to the severity of the delay of the impulse when passing from the main source of excitation to the atrioventricular node.

With minimal changes, all impulses slowly reach the end point. As the situation worsens, some potentials generated in the sinus node die out without reaching the AV connection.

Electrocardiographic signs

Violations of the mildest degree on the ECG do not have strictly individual signs. The cardiograph records the delay in the conduction of potentials through the atria, which is expressed in the prolongation of PQ intervals and PP distances without violating the RR ratios. In other words, the diagnostician will be presented with a picture of sinus bradycardia.

Second degree sinoatrial block is represented by 2 types:

complete extinction of one of the potentials with a preceding change in conduction delay (Samoilov-Wenckebach period);
unexpected interruption of sinus rhythm due to loss of a normal impulse.

Electrocardiographic signs of these disorders are the absence of timely appearance of the P wave. This manifestation may be preceded by a gradual reduction in the duration of PQ intervals during type 1 2nd degree blockade.

Degree 3 sinoauricular conduction disturbance on the ECG is recorded as a straight line without recording excitation from a normal source of impulses until the function of automatism is taken over by the downstream pacemaker.

Episodes of SA blockade 2 and other degrees can develop at any time of the day. In order to register changes of a temporary nature, a daily cardiogram is recorded (monitoring).

Symptoms

Minimal dysfunction in conduction along the sinoauricular junction can only be determined as a decrease in sinus rhythm (bradycardia); patients do not feel any interruptions in the heart.

SA blockade, starting from the 2nd degree, has clear clinical signs. During episodes, patients experience attacks of dizziness and complain of a feeling of irregular cardiac activity.

With a significant blockade, a fainting state develops due to insufficient blood supply to the brain, called a Morgagni-Adams-Stokes attack. Stopping breathing, involuntary urination and defecation, and convulsive readiness may accompany such fainting.

If, in the third degree of disturbance, the extinct sinus impulse is replaced by a rhythm from the atrioventricular connection, then patients do not notice any significant changes in their condition. Severe cases are characterized by complete asystole with the threat of sudden death.

Differentiated approach to diagnosis

The diagnosis is based on an assessment of the electrocardiogram with the possible inclusion of additional research and functional tests.

Blockade of the sinoatrial junction is differentiated from sinus bradycardia, in which the heart rate exceeds 40 beats per minute, in contrast to an abnormal slow rhythm with a frequency of 30–40 beats per minute.

An atropine test helps to make a final diagnosis. Immediately after administration of the drug, in the event of a blockade, the heart rate increases twofold, followed by a rapid decrease.

The presence of escape rhythms is a reason to clarify the nature of the arrhythmia, since replacement impulses are often similar to extrasystole, a change in the main source of excitation to atrial or atrioventricular.

Therapeutic tactics

First degree sinoatrial block often does not require treatment. In order to monitor the condition of the myocardium and avoid aggravation of the situation, the patient is periodically referred for an ECG and other cardiac studies.

If the patient has a history of taking medications that cause blocking of sinus impulses, it is necessary to reconsider medication prescriptions and switch to an alternative drug without this side effect.

In case of disturbance of sinoatrial conduction against the background of increased tone of the vagus nerve, they resort to the prescription of anticholinergics (atropine, platyphylline) and sympathomimetics (isadrine, ephedrine).

In the absence of a response to drug treatment, the presence of a blockade of degree 2, frequent episodes of Morgagni-Adams-Stokes attacks, and the threat of cardiac arrest are indications for deciding to install a pacemaker.

Forecast

The duration and quality of life of patients depend on the duration and form of conduction disturbance through the sinus node, the condition of the myocardium, and combination with other pathologies.

In general, the prognosis for this type of arrhythmias is better than for AV blockade. Short-term episodes of impulse delays in the sinoauricular region against the background of transient conditions do not aggravate the situation in general.

Constant manifestations of partial blocking of sinoatrial impulses can eventually transform into complete and advanced ones with the development of fainting attacks and the risk of sudden cardiac death.

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.

What is 2nd degree heart block?

If there are disturbances in the functioning of the sinus node, new sources can form in various areas of the heart muscle. They provide electrical impulses.

The presented new sources may have a negative impact on the sinus node, competing with it or aggravating its activity.

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Conducting cardiac system

Speaking about cardiac impulses, it should be noted that they are formed in the formation of the sinus node. It is located in the area of the right atrium and is the main one.

It is the sinus node that guarantees the frequency of rhythmic contractions, which are then transmitted to the atrioventricular node.

However, in such a situation, the degree of impulse frequency suffers, and, as a result, the rhythm, which decreases significantly (from 60 to 20 contractions).

Causes of pathology

2nd degree heart block occurs due to the following factors:

genetic predisposition and inherited pathologies;
coronary heart disease and myocardial infarction;
cardiosclerosis, angina pectoris, myocarditis;
consuming large dosages of medicinal components or using medications not according to medical recommendations;
change in the thickness of the heart muscle.

The heart rate of an adult in normal health is 60 to 80 repetitions per 60 seconds. If no heart contractions are observed within 3-5 seconds, then the person is likely to lose consciousness. He may also begin to have convulsive contractions, and in the absence of specialist help, death occurs.

The presented pathological phenomena occur occasionally or can be observed constantly. Atrioventricular block is identified using an ECG.

Differences between 2nd degree heart block

With 2nd degree heart block, not every impulse from the atria is conducted to the ventricular region, and therefore some contractions of the represented region are lost.

On the ECG, manifestations of deceleration or optimal complexes are identified first.

In some cases, atropine and isadrin are used. If the heart rate is significantly reduced, then permanent electrical stimulation of the heart is used, namely a pacemaker.

Treatment methods

When a blockade is formed due to pathologies of the heart (myocarditis or acute myocardial infarction), the leading disease is first dealt with.

The recovery algorithm for 2nd and 3rd degree blockages is selected taking into account where the disturbance is located within the conductivity:

Treatment is carried out with drugs such as isadrin or the introduction of atropine under the skin.
At the treatment stage, physical exercises are completely excluded. loads.

Drug therapy does not guarantee the desired effect.
The only treatment option is electrical stimulation of the heart muscle.
When the blockade is acute and occurs as a result of myocardial infarction, intermittent stimulation is carried out due to electricity.
With a stable blockade, the presented measure must be carried out continuously.

If stimulation is not possible, an Isuprelai or Euspiran tablet is placed under the patient’s tongue (in some cases, 0.5 tablets are used).
For introduction into the vein, these drugs are dissolved in a composition with glucose (5%).

Neutralized by eliminating glycosides.
If the blockage, the rhythm of which does not exceed 40 beats within 60 seconds, persists even after stopping glycosides, Atropine is introduced into the vein.
In addition, Unitol injections are injected into the muscles (up to 4 times during the day).
If there is such a need (for medical reasons), then temporary electrical stimulation is performed.

You can learn more about 2nd degree heart block here.

Under the influence of medicinal components on the vagus nerve, situations are possible in which absolute blockage of the heart is transformed into partial.

Folk remedies

The use of folk recipes to restore health during heart blockade is also recommended to be agreed with a specialist. But first of all, you need to follow basic lifestyle recommendations.

It is necessary to exclude the use of alcohol and cigarettes, and minimize the use of strong coffee and tea. It is undesirable to consume salt, as well as fried and fatty foods.

For a speedy recovery, salty and smoked dishes are excluded from the menu, and preference is given to fruits, vegetables, meat and fish with a low fat content, as well as similar dairy products.

Traditional medicine can offer the following simple recipes that will help the heart muscle function fully:

2 tsp. Dried finely chopped valerian root is poured into 100 ml of boiling water and boiled under the lid for 15 minutes.
The product is cooled and filtered; it should be consumed three times a day, 1 tbsp. l. before meals.

To prepare it, use 1 tbsp. l. pour 400 ml of boiling water with a heap of lemon balm herb and let it cool until it cools 100%.
After this, the product is filtered and taken 0.5 cups 3 times a day before eating.
The presented mixture is in great demand among athletes.

1 tsp. The flowers of the plant are poured with 200 ml of boiling water and heated in a water bath for 15 minutes.
The composition is cooled, filtered and diluted with water to 200 ml.
Drink 0.5 cups 30 minutes before meals.

It is necessary to avoid excessive physical and emotional stress, remember to adhere to a rest regime and carry out physical exercises as often as possible.

Consequences

The timing of disability is directly dependent on how difficult the leading disease is.

The prognosis depends on the underlying disease and the level of blockage. A pessimistic prognosis is associated with distal blockades, because they are prone to constant development - the consequences in this case will be the most severe.

if a primary attack of Morgagni-Adams-Strokes occurs and an pacemaker is not transplanted, then life expectancy is significantly reduced and will be no more than 2.5 years;
the survival rate of patients increases due to permanent stimulation;
the prognosis after transplantation is directly dependent on the nature of the leading disease.

If myocardial infarction of the anterior wall occurs, then with absolute blockade there is aggravated damage to the septum between the ventricles. This means that the prognosis is extremely unfavorable: the mortality rate from ventricular fibrillation or cardiac failure is identified in 90% of cases.

Read here what blockade of the left leg of the heart is.

The relationship between false chord and heart block is described in another article.

People should not neglect folk recovery methods, which will enable a person to live on without encountering blockades.

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

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.

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.

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.

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.

Manifestations and diagnostic methods of SA blockade

syncope with MAS syndrome due to sinus node blockade

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.

Treatment

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.