What is sssu in cardiology. What does the diagnosis mean - sick sinus syndrome (SSS)? Internal causes of sinus node weakness

Sinus node weakness syndrome is a type of functional lesion of the cardiovascular system, in which the natural pacemaker is not able to generate impulses sufficient to completely reduce all structures of force.

There is a similar phenomenon for pathological reasons, it is almost always secondary. Recovery is possible, a complete cure too, but the prospects are vague, depending on the underlying disease, general condition health, as well as specialist qualifications.

Organic abnormalities are associated with a worse prognosis, since it is potentially more difficult to normalize the work of cardiac structures.

Understanding the essence of the development of the disease is to determine the anatomical and physiological features.

The syndrome is based on a violation of the normal activity of the sinus node. This is a special accumulation of cells responsible for generating an electrical impulse of sufficient power. Under adequate conditions, the heart works autonomously, without third-party stimulation factors. Signal generation is the task of the pacemaker.

Under the action of certain moments, the intensity of the electric pulse decreases. It continues to be carried out along special fibers to the atrioventricular node and further along the legs of the His bundle, but the force is so small that it does not allow the myocardium to contract completely.

Recovery is radical, but not always surgical methods. The bottom line is to stimulate the "lazy" heart.

As the pathological process progresses, an even greater weakening in the work of myocytes is observed.

There is a violation of myocardial contractility, blood output decreases, hemodynamics suffers. Total functional defects often lead to organ failure, heart attack or coronary insufficiency.

Differences between sick sinus syndrome and sinus dysfunction

In fact, it is not necessary to distinguish between the pathological processes of the two described types. The described disease is considered a special case of disruption of the pacemaker. That's why The second term is general.

If we consider SSSU as a separate variety, it has the following characteristic, pathognomonic features:

• Intermittent bradycardia and tachycardia (a condition known as tachy-brady syndrome). This is not the only possible clinical type of process.
• Other forms of this disease are heart rate deviations in one direction or another. There is a weakening (not more than 40-50 beats per minute) or strengthening (from 100).
• It starts mostly in the morning. Relapses are possible at night.

In addition, the development of the syndrome of weakness of the sinus node is gradual, over the years. Other dysfunctions are characterized by aggressiveness, rapid forward movement.

Classification

Typification of the pathological process is carried out for a number of reasons.

Based on the origin of the disease, they talk about the following types:

• Primary SSSU. It develops against the background of cardiac problems themselves. Some doctors (theoreticians and practitioners) understand this term as the formation of a process without external factors. This is an extremely rare situation.
• Secondary variety. Formed under the influence of non-cardiac causes. Occurs in 30% of recorded cases.

Depending on activity, flow:

• latent type. It is determined in 15% of situations. This is the mildest form in most cases, because it has no symptoms and does not progress over a long period of time. The opposite option is also possible, when there is forward movement, aggravation too, but the patient does not feel anything.
• Acute manifest. It is characterized by the appearance of a severe attack of tachycardia or a weakening of the heart rate, with pronounced manifestations from the cardiac structures, nervous system. It is often impossible to distinguish the syndrome of weakness of the sinus node from other deviations on the move. Further, the course of the disease is determined by constant relapses.
• chronic type. The symptoms are always present. But as such, there are no exacerbations. The intensity of manifestations is also minimal. Basically makes itself felt tachycardia.

According to the severity of objective organic abnormalities:

• compensated form. The heart is still coping with disruptions. Adaptive mechanisms are activated, adequate myocardial contractility is observed.

This state of affairs can persist for years, in which case the patient does not even suspect that he is ill.

There are no symptoms or the clinical picture is minimal. Mild palpitations, slight shortness of breath or tingling in the chest. That's all that arises against the background of this type.

• decompensated form. Occurs more often. This is a classic option, in which the symptoms are sufficiently pronounced to determine health problems. But the manifestations are nonspecific. An objective diagnosis is required.

Finally, based on their options clinical picture and dominant feature:

• bradycardic appearance. The heart rate is reduced. Sometimes to a dangerous minimum of 40-50 beats per minute. It happens less. There is a threat of acute conditions, such as a stroke or Morgagni-Adams-Stokes attacks. Requires pacemaker implantation.
• Mixed, braditachysystolic type. There is an alternating alternation of acceleration and deceleration of the heart rate. It is possible to connect other arrhythmias, which aggravates the prognosis. The quality of life proportionally falls.

The presented classifications are clinically important, since they allow determining the vector of diagnosis and the development of competent therapeutic tactics.

Causes

Development factors are divided into two groups. The primary ones are caused by a violation of the work of the heart itself, as well as blood vessels. Secondary - extracardiac moments and diseases.

Primary

• ischemic heart disease. Accompanies patients over the age of 40. In rare cases, formation of violations in the early period is possible.

The bottom line is the impossibility of a normal supply of blood to the heart structures themselves.

Due to constant hypoxia, organic disorders develop: muscle mass increases, chambers expand. Weakness of the sinus node is a possible option, but is not always observed.

• Autoimmune pathologies affecting cardiac structures and vessels. Vasculitis, rheumatism, systemic lupus erythematosus and others.

Affect the muscle layer. Destruction of tissues leads to their replacement with scar fragments and development.

They cannot contract, do not have elasticity, hence the impossibility of adequate work. Blood is pumped with less intensity.

In the perspective of several years, this may result in total multiple organ dysfunction or emergency conditions.

• Inflammation of the heart (myocarditis) and surrounding structures. Infectious, less often autoimmune genesis. Recovery in the walls of the hospital, with the use of antibiotics and corticosteroids. Untimely assistance leads to tissue destruction, a minimum of severe disability, and a maximum of death.

• Cardiomyopathy. Violation of the growth of the muscle layer or the expansion of the chambers of the heart. Both conditions are potentially fatal if left untreated. Radical treatment is impossible, the use of maintenance drugs is required to stop the process. Duration beneficial effect- whole life.

• Operations on the heart. Even minor ones at first glance, like radiofrequency ablation, and others. There are no safe interventions on cardiac structures. There is always a risk of complications. So, against the background of cauterization of a large area, or if a functionally active, healthy area is treated, the likelihood of arrhythmia is higher.
• Heart injury. These lead to bruises of the chest, fractures of the ribs.
  Congenital and acquired organic deviations in the development of cardiac structures. Multiple in nature. Prolapse is considered the most typical mitral valve, other conditions that cause reverse blood flow (regurgitation), aortic insufficiency, and many others. In the early stages, they do not manifest themselves in any way. There may be no symptoms of defects up to the onset of death.

In rare cases - hypertonic disease running type.

Secondary factors

Non-cardiac problems are less common:

• Pronounced intoxications. There are many reasons for the state. From cancer processes of the advanced stage to poisoning with metal salts, decompensated liver diseases.
• Autonomic dysfunction (VGSU) appears frequently. Perhaps a temporary weakening of the sinus node as a result of vomiting, coughing, changes in body position, meteorological dependence, sports. Dystonia also plays a role. But this is not a diagnosis, but a symptom of a disease.
• Drug overdose antihypertensive, cardiostimulatory action. Long-term use of these funds leads to a similar result.
• metabolic processes associated with impaired potassium and magnesium metabolism.
• Syphilis, HIV, tuberculosis. Dangerous infectious or viral processes.
• Age from 50 years. The body loses the ability to adequately adapt to harmful external and internal factors. Therefore, the risks of developing pathologies of the cardiac profile are higher.
• Prolonged fasting, cachexia. It develops as a result of objective processes (cancer, infections, Alzheimer's disease, vascular and other dementia) or a conscious refusal of food (diet, anorexia).
• Endocrine disorders. Diabetes, hyperthyroidism (excessive production of thyroid hormones), the reverse process, deficient states in the part of the adrenal glands.

In the absence of data for organic pathologies, they speak of an idiopathic form. This is also a common option.

Recovery consists in relief of symptoms. The effectiveness of such a measure is controversial, without the etiotropic component, the action is incomplete.

Symptoms

Manifestations depend on the form and severity of pathological abnormalities. Possible signs include:

• Pain in chest. The intensity varies, from slight tingling to severe bouts of discomfort. Despite the pronounced severity, it is impossible to talk about the origin without a thorough diagnosis.
• , flutter, booming beat. In this case, tachycardia is replaced by the opposite phenomenon. Episodes last from 15 to 40 minutes or a little more.
• Dyspnea. The inefficiency of the lung structures is due to tissue hypoxia. In this way, the body tries to normalize oxygen metabolism. At the initial stage, when there are no defects yet (the size of the heart is normal, the muscle layer too, the systems work stably), the symptom occurs only with increased activity. It's still hard to notice. In the later stages, intense shortness of breath appears even at rest. Within the framework of advanced diagnostics, specific tests are carried out (bicycle ergometry as an example).
• Arrhythmias of a different type. In addition to accelerating the work of the heart, group or single extrasystoles.

The danger of a particular type is determined during the ECG and dynamic observation. Potentially lethal forms develop somewhat later from the onset of the main pathological process.

Cerebral structures suffer as a result of hemodynamic disturbance and decreased nutrition of the brain:

• Noise in the ears, ringing.
• Vertigo. It comes to the point that the patient cannot normally navigate in space. The inner ear, cerebellum suffers.
• Cephalgia of uncertain origin. Similar in character to that of high blood pressure or migraines.
• Fainting, syncope. Up to several times a day.
• Mental disorders. By the type of depressive episodes of a long nature, aggressiveness, increased irritability.
• Cognitive and mnestic deviations. The patient cannot remember important things, fill in new information. The efficiency of thinking decreases.
• Feeling of numbness of the limbs, weakness, drowsiness.

General symptoms:

• Paleness of the skin.
• Cyanosis of the nasolabial triangle.
• Decrease in working ability, ability to serve oneself in everyday life.

Symptoms of weakness of the sinus node are determined by cerebral, cardiac and general manifestations.

First aid for an attack

Methods of pre-medical exposure suggest a clear algorithm:

• Call an ambulance. It is carried out in the first place. Acute attacks are accompanied by a pronounced clinic, and the symptoms are nonspecific. These or those states are possible, up to lethal.
• Measurement blood pressure, heart rate. Both indicators against the background of deviations change upwards. Less often, asymmetry is possible (high blood pressure numbers with bradycardia).
• Open a window, a window for fresh air. Put on the head and chest soaked in cold water piece of fabric.
• Lie down, move as little as possible.

Preparations can not be used, just as you should not resort to folk recipes.

Rhythm restoration during heart rate acceleration is carried out by vagal methods: deep breathing, pressure on the eyeballs (in the absence of ophthalmic conditions).

When the heart stops, a massage is shown (120 movements per minute, with squeezing of the sternum by several centimeters).

The patient can be brought out of a faint with the help of ammonia. Ammonia solution does not need to be placed under the nose of the patient, burns of the respiratory tract are possible.

Moisten a cotton swab and hold it several times in front of the victim, about 5-7 cm. Before regaining consciousness, it is recommended to turn the head to the side and release the tongue.

Upon the arrival of the ambulance, the issue of transporting the patient to the hospital is decided. You should not refuse, you need to find out the source of the phenomenon that has begun.

Diagnostics

Patients are examined by cardiologists. Specialists in CNS pathologies and hormonal problems can also be involved in determining the origin of the process.

List of events:

• Oral questioning of a person and collection of anamnestic data.
• Measurement of blood pressure, counting the heart rate.
• Electrocardiography. Basic technique. Provides an opportunity to determine the nature of functional disorders in the short term.
• Daily monitoring. The bottom line is to assess blood pressure and heart rate for 24 hours.
• Echocardiography. Visualization of cardiac structures. One of the main methods of early detection of organic defects.
• MRI as indicated to obtain clear images.
• Coronography.

Also, an assessment of the neurological status, a blood test for hormones, a general, biochemical one. Diagnosis is carried out on an outpatient or inpatient basis. In the second case, it's faster.

Signs on the ECG

The weak work of the sinus node has several specific features on the cardiogram:

• Complete disappearance of P waves.
• Deformation of peaks, untimely appearance of the QRS complex, its absence.
• Extraordinary contractions against the background of extrasystole, which occurs frequently.
• Bradycardia or acceleration of cardiac activity.

There are many more features. Tertiary or secondary pathologies are represented by blockades, fibrillation. Some signs overlap with others.

Ways of treatment

The essence of therapy is to eliminate the underlying pathology (etiotropic technique) and relieve symptoms. Medicines are used, surgery is less often performed.

Preparations:

• Antiarrhythmic. As part of the restoration of an adequate rhythm.
• Antihypertensive. different types. From calcium channel blockers to ACE inhibitors.
• Against the background of emergency conditions, stimulants are used (Epinephrine, Atropine). With great care.

Cardiac glycosides are generally not used due to possible cardiac arrest.

The surgical technique involves the implantation of a pacemaker, and the elimination of malformations of cardiac structures.

Treatment will not be effective if complicating factors are present. They not only prevent adequate recovery, slowing down or completely leveling the effect, but also increase the risk of dangerous consequences.

• Give up bad habits: smoking, drinking alcohol, drugs.
• At long-term treatment physical and mental disorders, it is necessary to adjust the therapeutic course so that it does not harm the heart.
• Full rest (8 hours of sleep per night).

Ration does not play a special role. However, it is recommended to fortify the menu, consume more foods containing potassium, magnesium, and protein.

Predictions and possible complications

The outcome of the process is determined by the severity of the condition, stage, dynamics, and the health of the patient in general. Lethality is minimal.

Death is due to secondary or tertiary diseases. The average survival rate is 95%.

With the addition of fibrillation, extrasystoles are sharply reduced to 45%. Treatment improves prognosis.

The consequences are:

• Heart failure.
• Heart attack.
• Stroke.
• coronary insufficiency.
• Cardiogenic shock.
• vascular dementia.

Finally

The sinus node is a collection of cells that generate electrical impulse providing contraction of all cardiac structures.

The weakness of this formation entails insufficient activity of the organ. The inability to provide blood not only to distant systems, but also to oneself.

The reasons are diverse, which makes it difficult to diagnose early.

Treatment is carried out by a cardiologist or a specialized surgeon. The duration of therapy can reach decades. Lifetime support in some cases is the only possible option.

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Treatment Goals

Prevention of SCD due to bradyarrhythmia, elimination or relief clinical manifestations diseases, as well as prevention possible complications(thromboembolism, cardiac and coronary insufficiency).

Indications for hospitalization

• Severe symptoms of the disease. So, in the case of fainting, frequent pre-syncope conditions, emergency hospitalization is indicated.
• Planned pacemaker implantation.
• The need to select antiarrhythmic therapy for bradycardia-tachycardia syndrome.

Non-drug treatment

Not drug treatment patients with coronary artery disease, hypertension, heart failure includes standard dietary recommendations, as well as psychotherapeutic effects. In addition, drugs (if possible) that may have caused or exacerbated SSSS (eg, beta-blockers, calcium channel blockers, class I and III antiarrhythmic drugs, digoxin) should be discontinued.

Medical treatment

The options for medical treatment of SSS are limited. Therapy of the underlying disease that caused the development of SSSU (etiotropic treatment) is carried out according to general rules. In emergency cases (severe sinus bradycardia, which worsens hemodynamics), 0.5-1 ml of a 0.1% solution of atropine is injected intravenously. If symptoms persist, a temporary pacemaker is established. In the event of an attack of Morgagni-Adams-Stokes, resuscitation is necessary.

With severe symptoms, to increase heart rate, Belloid can be prescribed (1 tablet 4-5 times a day), prolonged forms of theophylline (75-150 mg 2-3 times a day). However, when using these drugs, it is necessary to remember the danger of provoking heterotopic arrhythmias. Therapy of concomitant tachyarrhythmias should be carried out with great caution. Almost all modern antiarrhythmic drugs have an inhibitory effect on the function of the sinus node. This property is somewhat less pronounced in allapinin, a trial appointment of which in small doses (12.5 mg 3-4 times a day) is possible.

In patients with vagotonic dysfunction of the sinus node, in contrast to SSS caused by organic causes, conservative therapy is of primary importance. Treatment of vegetative dystonia is carried out according to general principles, including measures aimed at limiting parasympathetic effects on the heart (they do not recommend wearing clothes that squeeze the neck, they treat concomitant pathology of the gastrointestinal tract), dosed physical activity, and rational psychotherapy. A positive effect in such patients gives clonazepam at a dose of 0.5-1 mg at night with a possible subsequent increase in dose to 1.5-2 mg in 2-3 doses. The drug allows you to correct psychovegetative disorders leading to the formation of vagotonic dysfunction of the sinus node, which is manifested by the elimination of not only fainting, weakness, dizziness, but also a decrease in the severity of bradycardia and other ECG signs. In patients with sleep apnea syndrome with adequate treatment this disease(CPAP therapy, surgical treatment) observe the disappearance or decrease in the manifestations of sinus node dysfunction.

Surgery

The main method of treating organic SSSU is the implantation of a permanent pacemaker.

Indications for pacemaker implantation in SSSU are divided into classes.

• Sinus node dysfunction with documented bradycardia or pauses accompanied by symptoms, including as a result of therapy that cannot be canceled or replaced.
• Clinically manifest chronotropic incompetence.

Class IIa.

• Sinus node dysfunction with heart rate less than 40 per minute and clinical symptoms in the absence of documentary evidence that the symptoms are due to bradycardia.
• Syncope for unknown reasons, in combination with violations of the function of the sinus node identified during an electrophysiological study.

Class IIb.

• Minimal symptomatology with a heart rate in the waking state of less than 40 per minute.

In patients with SSSU, it is preferable to use the pacemaker in AAI or (with concomitant AV conduction disorders) DDD, and in cases of symptomatic chronotropic insufficiency - AAIR or DDDR.

Approximate periods of incapacity for work

Approximate terms of disability are determined by the severity of the underlying disease. As a rule, in the absence of complications, the terms of hospitalization for pacemaker implantation rarely exceed 10-15 days. Patients cannot work in professions that threaten the safety of others.

Further management

Further management of patients with SSSU includes:

• control of the ECS system, selection of stimulation parameters, determination of the time for replacing the ECS, carried out in specialized arrhythmological centers;
• treatment of the underlying disease;
• treatment of concomitant tachyarrhythmias.

Information for the patient

The patient is recommended to regularly undergo preventive control of the EKS system. If new symptoms occur or recurrence of previous symptoms (fainting, dizziness, shortness of breath on exertion), you should immediately consult a doctor.

Patients with SSS who have not been implanted with a pacemaker are prohibited from taking any antiarrhythmic drugs (especially β-blockers, verapamil, cardiac glycosides) without prior consultation with a cardiologist.

Daily monitoring of heart rate is necessary, and if aggravation of bradycardia is detected, immediate medical attention should be sought. Periodic ECG registration is shown (the frequency is determined by the attending physician), and, if necessary, Holter ECG monitoring.

Forecast

With timely implantation of the pacemaker, the prognosis for life and recovery is regarded as favorable. In 19-27% of patients with SSSU, a permanent form of AF is established within 2-8 years, which can be equated to self-healing from SSSU.

Tsaregorodtsev D.A.

Sick sinus syndrome (SSS) combines in its concept some types of disorders heart rate, the cause of which is a pathological change in the work of the sinus node. This disease is characterized by the obligatory presence of bradycardia. Often, against the background of pathologists, ectopic foci of arrhythmia occur.

Along with the true syndrome of weakness of the sinus node, in which organic cell damage occurs, 2 more forms of the disease can be distinguished. These include impaired autonomic function and drug dysfunction of the node. The last two variants of the pathology are eliminated when the function of the corresponding part of the nervous system is restored or the drug that caused the decrease in heart rate (HR) is discontinued.

The disease is accompanied by weakness, dizziness or fainting. The diagnosis is made on the basis of electrocardiography (ECG) or Holter monitoring. The course of the SSSU is very diverse. With a proven diagnosis, the installation of an artificial pacemaker (IVR) is indicated - a permanent pacemaker.

Sinus node pathology most often occurs in the elderly. The average age is 60-70 years. A study by scientists from the United States showed that the disease occurs in 0.06% of the population over 50 years of age. By gender, there is no predisposition to the disease. SSSU can also manifest in childhood.

Causes of the disease

The syndrome of weakness of the sinus node usually leads either to an organic pathology, which is the culprit of structural changes in cells, or to external etiological factors. The latter lead to a violation of only the function of the source of the heart rhythm. Sometimes the causes of SSS are both factors at the same time.

Organic pathology causing SSSU:

1. degenerative disorders. The most common cause of sinus node disease is its fibrosis. In this case, the automaticity of the rhythm source and the degree of conduction of the nerve signal through it are reduced. There is evidence of a genetic predisposition to such changes. Fibrosis can be caused by:
   • sarcoidosis;
   • heart tumors.
2. Ischemic heart disease (CHD). This disease rarely leads to SSS, however, its role is quite large. Here we are talking about both acute ischemia (myocardial infarction) and chronic form. The main reason for the development of the pathology of the sinus node in this case is its insufficient blood supply:
   • atherosclerosis of the right coronary artery, which feeds the node;
   • thrombosis of vessels that bring blood to the source of rhythm (observed with lateral or lower myocardial infarction).

   It is for this reason that heart attacks with such localization are often accompanied by bradycardia (up to 10% of cases).

3. Arterial hypertension (hypertension) is chronically high blood pressure.
4. Heart injury due to heart transplant.
5. Hypothyroidism is a deficiency of thyroid hormones in the body.

External factors leading to dysfunction of the sinus node:

1. Violation of the autonomic nervous system:
   • increased activity vagus nerve(causes a decrease in heart rate);
   • physiological increase in its tone (observed during urination, vomiting, swallowing, defecation and coughing);
   • with diseases of the digestive tract and urinary system of the body;
   • increased tone of the vagus nerve with sepsis (blood infection), elevated levels of potassium in the blood, or hypothermia.
2. The effect of drugs that can reduce the function of the sinus node:
   • beta-blockers (Anaprilin, Metoprolol);
   • some calcium channel blockers (Diltiazem and Verapamil);
   • cardiac glycosides (Strophanthin, Digoxin);
   • various antiarrhythmic drugs (Amiodarone, Sotalol, etc.)

The pathogenesis of sick sinus syndrome

For a complete understanding of the mechanism of development of SSSU, it is necessary to know and understand the anatomical and physiological features of the cells of the sinus node.

Sinus node in the diagram of the adductor system of the heart This node, which is the main source of heart rhythm, is located in the right atrium and consists of cells that regularly generate a nerve impulse. Further, the latter spreads along the conduction system of the myocardium, causing its contraction.

Due to the fact that the sinus node is a constant source of rhythm, it is forced to work in various conditions. For example, during physical activity, human organs and systems require a larger amount of oxygen. This causes the heart to beat faster. The frequency is set by the sinus node. The change in heart rate is achieved by switching the work of the centers of the node. Thus, some structural elements are able to generate impulses with a minimum frequency, and some are tuned to a maximum heart rate.

With ischemia of the arteries supplying the sinus node, or with its other lesions, there is a lack of nutrition and some cells of the node are replaced connective tissue. Extensive death and structural changes in the elements of the rhythm source are isolated into a separate disease - idiopathic dystrophy.

The affected centers responsible for the minimum frequency begin to work incorrectly - they are excited less often and cause bradycardia (a decrease in the frequency of heart contractions).

Clinical manifestations of SSSU

In some patients, there is a shortage of blood supply to various organs, which leads to corresponding symptoms. Not always a decrease in heart rate leads to a lack of tissue nutrition, because. when this condition occurs, compensatory mechanisms are activated that promote adequate blood circulation.

The progression of the disease is accompanied by symptoms associated with bradycardia. The most common manifestations of SSS are:

• dizziness;
• fainting;
• pain in the region of the heart;
• labored breathing.

The above manifestations are of a transient nature, i.e. arise spontaneously and cease in the same way. The most common symptoms:

1. Cerebral. These include irritability, feeling tired, memory impairment, and mood swings. With the progression of the disease, loss of consciousness, tinnitus, convulsions occur. In addition, SSSU is often accompanied by a decrease in blood pressure (BP), cold sweat. Over time, signs of dyscirculatory encephalopathy appear: dizziness, sharp “lapses” in memory, speech impairment.
2. Cardiac (heart). The very first complaints patients present are the sensation of an irregular slow heartbeat. Due to the lack of blood circulation of the heart, pain behind the sternum appears, shortness of breath develops. Heart failure, ventricular tachycardia and fibrillation may occur. The last two manifestations often significantly increase the risk of sudden coronary (cardiac) death.
3. Other symptoms. Among the manifestations of SSS, not related to circulatory disorders of the brain and heart, there are signs kidney failure(oliguria - low urine output), gastrointestinal manifestations and muscle weakness (intermittent claudication).

Diagnostics

Because 75 out of 100 people with sick sinus syndrome have severe bradycardia, this symptom can be considered as the basis for the assumption of pathology. The basis of diagnosis is the removal of the electrocardiogram (ECG) at the time of the attack. Even in the presence of a pronounced decrease in heart rate, it is unambiguously impossible to speak of SSSU. Any bradycardia can be a manifestation of a violation of its autonomic function.

Methods used to determine sick sinus syndrome:

1. Holter monitoring.
2. Medical tests and tests with physical activity.
3. Electrophysiological intracardiac study.
4. Definition of clinical manifestations.

To choose a treatment it is important to determine the clinical form of pathology.

1. Bradyarrhythmic. The main manifestations are associated with impaired hemodynamics. Morgagni-Edems-Stokes attacks may occur (due to lack of cerebral circulation). The ECG shows an abnormal rhythm with a reduced heart rate. However, this sign is not always a consequence of SSSU. Similar electrocardiographic changes occur when atrial fibrillation is combined with atrioventricular block.
2. Tachy-bradyarrhythmic. Before and after a tachycardia attack, pauses are recorded on the ECG ( R-R increase interval). This variant of SSSU is characterized by a protracted course and often turns into a permanent replacement atrial fibrillation.
3. Bradycardic. With this form of SSSU, bradycardia with a rhythm source in the sinus node is determined first at night. Along with this, replacement rhythms are recorded. The initial stages of this variant of the disease are recognized only with the help of Holter monitoring.
4. Posttachycardic. This option differs from the previous ones by longer pauses that occur after an attack of atrial fibrillation or tachycardia.

Sometimes initial symptom SSSU is a violation of sinoatrial conduction, as a result of which the transmission of a nerve impulse to the atria is blocked. ECG clearly shows an increase interval P-P two, three or more times.

The disease progresses in the form of one of the above options. Further, SSSU develops into an expanded form, when any symptoms of the pathology begin to be undulating. Separately allocated three variants of the course of the disease:

1. Latent.
2. Intermittent.
3. Manifesting.

The latent variant is not determined even with repeated Holter monitoring. It is diagnosed using an intracardiac electrophysiological study. To do this, medical denervation is performed (artificial disruption of the conduction of nerve signals to the sinus node from the autonomic nervous system). Such a course in most cases is observed in violation of sinoatrial conduction.

The intermittent variant is characterized by the occurrence of a decrease in heart rate at night. This is due to a decrease in sympathetic influence and an increase in the parasympathetic function of the autonomic nervous system.

The manifesting course develops with the progression of the disease. In this case, the manifestations of SSS can also be determined using Holter monitoring, because. they occur more than once a day.

Treatment

SSSU therapy begins with the elimination of various factors that theoretically can lead to impaired conduction. To do this, the first step is to cancel such drugs.

If the patient has an alternation of tachycardia with bradycardia, but the decrease in heart rate is not critical, then under the control of Holter monitoring, Allapinin is prescribed in the minimum dosage several times a day. Disopyramide is used as an alternative drug. Over time, the progression of the disease still reduces the heart rate to the minimum allowable. In this case, the drug is canceled and a pacemaker is implanted.

When deciding whether to install a pacemaker (IVR-artificial pacemaker), it is imperative to exclude hypothyroidism and hyperkalemia in a patient. In these conditions, a functional occurrence of bradycardia is possible.

With the acute development of SSSU, it is advisable to treat the cause that caused the pathology:

1. In case of suspicion of inflammatory changes in the sinus node, therapy is started with Prednisolone.
2. A pronounced decrease in heart rate with impaired hemodynamics (blood circulation of the whole body) is stopped by the introduction of an Atropine solution.
3. In the absence of heart contractions (asystole), resuscitation is immediately carried out.
4. To prevent the dangerous manifestations of sick sinus syndrome, an endocardial pacemaker is sometimes installed.

Basic principles of treatment of sick sinus syndrome:

1. In the case of minimal manifestations - observation.
2. With a moderately severe clinic, conservative therapy is indicated. medicines aimed at preventing manifestations.
3. In a severe case, surgical therapy (IVR implantation).

• bradycardia less than 40 beats per minute;
• Morgagni-Edems-Stokes attacks in history. Even in the presence of a single case of loss of consciousness;
• pauses between heartbeats for more than 3 seconds;
• the occurrence of dizziness, fainting, heart failure or high blood systolic pressure due to SSS;
• cases of a disease with rhythm disturbances in which it is impossible to prescribe antiarrhythmic drugs.

IN modern world the vast majority of people with installed artificial pacemakers suffer from SSSU. This method of treatment does not increase life expectancy, but significantly improves its quality.

The choice of pacing method should provide not only adequate ventricular systolic function. To prevent the formation of blood clots and the corresponding complications, it is imperative to organize a normal rhythmic contraction of the atria.

SSSU forecast

Since the disease almost always progresses over time, patients' symptoms worsen. According to statistics, SSSU increases the level of total mortality by 4-5%.

Concomitant pathology of the heart of an organic nature has an adverse effect on the general condition of the human cardiovascular system. In view of the fact that thromboembolism is a frequent (about 40-50%) cause of death in cardio-diseases, the prognosis of CVD depends on the degree of risk of thrombi in the heart cavities.

With sinus bradycardia without cardiac arrhythmia, the risk of complications is minimal. The variant of SSS with sinus pauses slightly increases the risk of thrombi. The worst prognosis is with alternating bradycardia with tachyarrhythmias. In this case, the highest probability of developing thromboembolism.

Despite the prescribed treatment, sudden coronary death can occur at any time in SSSU. The level of risk depends on the severity of diseases of the cardiovascular system. If left untreated, patients with sick sinus syndrome can live for absolutely any amount of time. It all depends on the form of the disease and its course.

Prevention

To prevent SSSU, like all heart diseases, lies the right lifestyle and the rejection of bad habits. Specific prevention consists in the timely diagnosis of abnormalities in the work of the heart and the correct prescription of drugs.

Thus, it can be said that the standard of living and its duration in sick sinus syndrome depends on various factors. With the right choice of treatment, the risk of coronary death can be reduced to a minimum.

Sick sinus syndrome combines in its concept various cardiac arrhythmias, the main cause of which is considered pathological changes work of the sinus node. This disease is characterized by the presence of bradycardia, and often additional foci of arrhythmia occur.

To get rid of the ongoing pathology, it is important to conduct a timely diagnosis and subsequent comprehensive treatment.

Features of the course of the disease

In the heart muscle there is a center that sets the rhythm of its beating. This function is performed by the so-called sinus node, which is considered a pacemaker. It creates an electrical impulse and redirects it to the heart.

The sinus node of the heart is located in the right atrium in the area where the union of the vena cava occurs. It is a kind of power plant that distributes charges that set the rhythm of the beating of the heart muscle. The deterioration of the functioning of this organ creates various kinds of interruptions in the functioning of the heart. This pathology manifests itself equally in both sexes and often occurs in older people.

Sick sinus syndrome is not one specific disease, but several combined heart rhythm disturbances. This concept includes:

• bradycardia;
• tachycardia;
• mixed type.

Such a pathology is quite common and responds well to therapy, especially in the initial stages of the course of the disease. To determine the presence of a disease, it is imperative to know the causes that provoke it and the characteristic signs.

Classification of the course of the disease

Many people wonder, sinus arrhythmia - what is it, how is this disease classified and what is characteristic of it? We can distinguish such types of pathologies as:

• sinus bradycardia;
• tachycardia-bradycardia syndrome;
• sinoatrial blockade;
• fading of the sinus node.

Bradycardia is characterized by the fact that there is a decrease in the number of impulses and this leads to a decrease in contractions of the heart muscle. If less than fifty contractions occur per minute, then this is considered the main sign of bradycardia.

The syndrome of bradycardia-tachycardia is characterized by the fact that periods of slow work of the heart muscle are replaced by a rapid heartbeat. Sometimes, with the subsequent development of the pathology, atrial fibrillation is observed.

When the sinus node functions unchanged, however, a failure occurs during the transmission of impulses. The rhythm of contraction of the heart muscle largely depends on how clearly and evenly the blockade of the impulse occurs.

Stopping the sinus impulse implies that the pacemaker takes a break in the generation of the impulse for a certain time. Violation of the activity of the node also differs in the nature of the course of the pathology, namely, it is divided into:

• latent course;
• intermittent flow;
• manifest flow.

It is expressed in the fact that the violations of the functioning of the sinus node are almost imperceptible. Failures are very rare and pathology can only be detected during a comprehensive examination.

The intermittent course of the disease is characterized by the fact that the weakness of the sinus node is observed mainly at night. This is due to the impact on the work of the rhythm of the vegetative system. With a manifesting course of pathology, malfunctions in the work of the heart appear more pronounced.

Causes of pathology

There are a variety of reasons that provoke the weakness of the sinus node, which can be external and internal. The most common internal causes include:

• replacement of cardiac muscle cells with connective tissue;
• coronary artery disease;
• atherosclerosis;
• surgery and trauma;
• inflammatory processes, regardless of the peculiarities of their origin;
• autoimmune diseases;
• violation of protein metabolism.

Also, predisposing factors may be metabolic disorders, lack or excess of hormone production. thyroid gland, diabetes, constant change in weight.

The most common external cause of SSSU (ICD 10 - I49.5) may be the excessive influence of the department of the nervous system responsible for the activity of many internal organs. This condition occurs when:

• injuries of the nervous system;
• the presence of malignant neoplasms in the brain;
• cerebral hemorrhage;
• systematic use of certain medications.

In children, weakness of the sinus node is observed mainly with diphtheria, and in the elderly - with atherosclerosis of the coronary vessels. Failures in the functioning of this section of the heart muscle occur mainly in patients with acute myocardial infarction. Often the cause is acute heart failure.

node weaknesses

In order to timely recognize the course of the pathology, it is imperative to know sinus arrhythmia - what is it and what are the signs of the disease? Violations can manifest themselves in completely different ways, depending on the primary pathology that provoked them. Initially, the disease is mostly asymptomatic. Patients may not even notice interruptions in the contraction of the heart muscle lasting several seconds.

In some patients, at the very beginning, there may be problems with blood circulation in the area of ​​​​the brain and other organs, which leads to the appearance of appropriate clinical manifestations. Subsequently, with further progression of the pathology, a decrease in the number of heart contractions is noted. The severity of this pathology depends largely on the general condition of the cardiovascular system.

The main signs of sick sinus syndrome in the initial stages include:

• dizziness;
• feeling of heartbeat;
• fainting state;
• chest pain;
• shortness of breath

Such symptoms are non-specific, which is why it is necessary to conduct a comprehensive diagnosis to select the most appropriate method of therapy. Sinus node dysfunction syndrome is divided into two separate groups, namely, a violation of the activity of the brain, as well as the presence of problems from the heart.

In case of violation of the activity of the brain, such main signs of the pathological process can be distinguished as:

• increased irritability;
• emotional instability;
• constant feeling of tiredness;
• memory deterioration.

Elderly people may also experience a decrease in intellectual abilities. With the subsequent progression of the pathological process, circulatory disorders occur, which provokes the occurrence of more pronounced symptoms. and dizziness may be accompanied by severe weakness and the appearance of tinnitus. As a result of deterioration in the functioning of the heart muscle, there may be a sharp drop in pressure, accompanied by excessive pallor and cooling of the skin.

Symptoms of weakness of the sinus node with violations of the heart muscle at the initial stage are practically not manifested in any way. With the progression of the pathology, pain behind the sternum is noted, which occurs as a result of deterioration in the blood supply to the myocardium. With increased physical activity, patients complain of severe weakness and shortness of breath. If the patient is not given timely medical care, it can lead to chronic heart failure. In the later stages of the pathological process, there may be a fatal outcome.

Diagnostics

For the timely determination of the presence of pathology and complex treatment, it is important to diagnose the weakness of the sinus node, which is carried out using several different methods. The main method is the removal of the electrocardiogram at the time of the attack. In addition, diagnostic methods such as:

• Holter monitoring;
• drug tests with physical activity;
• intracardiac;
• definition of symptoms.

Holter monitoring involves the use of a portable electrocardiograph, which records the activity of the heart muscle throughout the day. This is very convenient, since it is possible to detect the latent course of the pathological process. At the same time, the patient can live his usual life and perform basic processes. By analyzing the data obtained, it is possible to determine the main cause of sinus node dysfunction.

Exercise tests are also carried out, during which certain increased requirements are created for the patient's heart. During physical activity the level of oxygen that is required by the myocardium for metabolic processes increases. This test will determine the signs of oxygen starvation.

Carrying out treatment

Treatment of the sinus node begins with the elimination of the main factors that can provoke a conduction disorder. For this, the prescribed medications are initially canceled. The main method of therapy, which guarantees the best result, is the installation of a pacemaker.

In addition to eliminating external causes, there must be observance of the optimal level of load, the exclusion of bad habits. It is also necessary to reduce the amount of caffeinated drinks consumed. If there is chronic diseases that affect the work of the sinus node, then it is imperative to treat them.

Medical treatment

If there is an increased activity of the nervous system responsible for the activity of the internal organs, or there are other, more serious disorders, then medical treatment of weakness of the sinus node is carried out. The doctor prescribes drugs that help eliminate dysfunction.

When conducting drug therapy, it is necessary to avoid taking drugs that provoke a decrease in the number of heart contractions and a decrease in pressure. In emergency cases, the patient is given the drug "Atropine". Taking medications is aimed only at eliminating the main symptoms and is a preparatory stage in the surgical intervention.

Surgery

To eliminate sinus node dysfunction, it is necessary to install permanent pacing in the patient's body. There are certain indications for the installation of a pacemaker, which include:

• the simultaneous presence of bradycardia and other cardiac arrhythmias;
• bradycardia with an excessively reduced pulse rate;
• loss of consciousness with epileptic seizures;
• coronary insufficiency, regular dizziness and fainting.

In this case, the installation of a pacemaker is necessarily indicated, since if treatment is not carried out in a timely manner, the consequences can be more serious, up to death.

The use of folk remedies

Self-medication with weakness of the sinus node is unacceptable, which is why it is necessary to consult with your doctor before using alternative therapy methods. During therapy with traditional medicine special infusions are made from medicinal plants, in particular, such as:

• motherwort;
• mint;
• valerian;
• yarrow.

These medicinal herbs help normalize sleep, fight stress, and improve well-being.

Carrying out prevention

In order to prevent deterioration of the condition, it is imperative to carry out competent prevention. It implies adherence to the principles rational nutrition, you need to control the regime of the day. The daily diet should contain foods with a high content of magnesium and potassium, which help maintain the performance of the heart muscle.

Physical activity must be regular, and the load increases depending on the state of health and well-being of the patient. You need to try to eliminate psycho-emotional stress and stress from your life. To calm the nervous system, it is advisable to use natural remedies and stop taking medications.

It is also necessary to control the amount of sugar in the blood and monitor weight gain in children and adults. It is impossible to take medications uncontrollably, since even the most harmless medicines can cause a deterioration in the activity of the heart muscle. It is imperative to undergo timely examination and treatment in order to prevent the transition of the disease to a more complex stage.

Forecast and consequences

It is important to remember that sick sinus syndrome is a dangerous disease that can have many negative consequences. This pathology occurs mainly in older people, however, recently it has also been diagnosed in young children, as well as adolescents. The consequences of the course of the disease can be very serious, in particular such as:

• the formation of permanent sinus bradycardia;
• regular blocking of the heart for a few seconds;
• blocking the transmission of impulses of the sinus node;
• frequent bouts of tachycardia;
• atrial flutter.

With incorrect or untimely treatment of the pathological process, a stroke can occur, and this can cause damage to brain tissue and impaired brain function. In addition, the formation of blood clots can be a consequence of such a disease, which is very life-threatening, since if a blood clot breaks off from the walls of blood vessels, this can lead to death.

Another pathology can be heart failure, which is often formed in the absence of timely therapy and the progression of the disease.

The violation of impulse conduction by the pacemaker center itself is not dangerous and does not have a negative impact on the patient's life expectancy. The threat is only those consequences that can be provoked by the course of the pathology.

The prognosis for life expectancy will largely depend on the nature and degree of damage. If violations in the work of the sinus node were formed as complications as a result of the course of the underlying disease, the prognosis for further survival will depend on how severe the damage to the body was.

a common part

Sick sinus syndrome (SSS)- a clinical and pathogenetic concept that combines a number of rhythm disturbances caused by a decrease in the functional ability of the sinus node. Sick sinus syndrome occurs with bradycardia / bradyarrhythmia and, as a rule, with the presence of concomitant ectopic arrhythmias.

In addition to true SSSU, caused by an organic lesion of the sinus node, there are autonomic sinus node dysfunction and drug-induced sinus node dysfunction, which are completely eliminated, respectively, with medical denervation of the heart and the abolition of drugs that suppress the formation and conduction of the sinus impulse.

Clinical manifestations of sick sinus syndrome may be mild or include a feeling of weakness, palpitations, and fainting (Morgani-Edems-Stokes syndrome).

The diagnosis is based on ECG data, Holter ECG monitoring, stress tests, and invasive studies - intracardiac electrophysiological study and transesophageal electrophysiological study.

There are latent, intermittent and manifesting course of SSSU, as well as several variants of its course.

Patients with the presence clinical symptoms as a rule, implantation of artificial pacemakers is indicated.

Epidemiology of sick sinus syndrome

Sick sinus syndrome is more common among the elderly and senile (peak incidence occurs at 60-70 years of age), therefore, it is more common in countries with high average life expectancy. An epidemiological study conducted in the United States showed that SSSU occurs in 3 out of 5000 patients over the age of 50 years.

Sick sinus syndrome can also occur in childhood and adolescence.

The disease occurs equally often in both men and women.

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Etiology and pathogenesis

Etiology of Sick Sinus Syndrome

There are two main groups of factors that can cause sinus node dysfunction.

The first group of factors includes diseases and conditions that cause structural changes in the cells of the sinus node and (or) changes in the atrial contractile myocardium surrounding the node. Data organic lesions are defined as internal etiological factors that cause sick sinus syndrome.

The second group of factors includes external factors that lead to dysfunction of the sinus node in the absence of any morphological changes.

In some cases, there is a combination of internal and external factors.

Organic lesions (intrinsic factors) that can cause sinus node dysfunction

External factors that can cause dysfunction of the sinus node

The pathogenesis of sick sinus syndrome

The sinus node is a complex of pacemaker cells; its main function is the function of automatism.

To implement the automatism function, it is required that the impulses generated in the sinus node are conducted to the atria, i.e. normal sinoauricular (SA) conduction is required.

Since the sinus node has to function under the conditions of various needs of the body, various mechanisms are used to ensure adequate heart rate: from changing the ratio of sympathetic and parasympathetic influences to changing the source of automatism within the sinus node itself.

According to modern concepts, in the sinus node there are centers of automatism responsible for rhythm control with different frequencies of impulse formation, therefore (with a somewhat simplified consideration) some centers are responsible for the formation of the minimum, and others - the maximum heart rate.

Under certain physiological and pathological conditions, for example, when the vagus nerve and fibers of the sympathetic part of the autonomic nervous system are excited, electrolyte metabolism disorders, groups of cells that perform the function of a back-up pacemaker with a less pronounced ability to automatism are capable of becoming pacemakers of the heart, which may be accompanied by minor changes R wave shapes.

Favorable conditions for the occurrence of dysfunction of the sinus node are also created by the extremely low speed of propagation of impulses through its constituent cells (2-5 cm / s). However, any relatively small deterioration in conduction due to dysfunction of the autonomic nervous system or organic damage to the myocardium can cause intranodal blockade of impulses.

Ischemia due to stenosis of the sinus node artery or more proximal segments of the right coronary artery, inflammation, infiltration, as well as necrosis and hemorrhage, the development of interstitial fibrosis and sclerosis (for example, in surgical trauma) lead to the replacement of sinus node cells with connective tissue.

In a large number of cases, dystrophy of specialized and working cardiomyocytes in the area of ​​the sinus node with the formation of interstitial fibrosis and sclerosis has the character of idiopathic dystrophy.

Electrophysiological mechanisms of the development of sick sinus syndrome

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Clinic and complications

The clinical manifestation of sick sinus syndrome may be different, due to the fact that this disease is a heterogeneous disorder.

In the early stages of the disease, most patients are asymptomatic. The course of sick sinus syndrome can be asymptomatic even with pauses of 4 seconds. and more.

Only in some patients, a decrease in heart rate causes a deterioration in cerebral or peripheral blood flow, which leads to complaints.

As the disease progresses, patients report symptoms associated with bradycardia. The severity of bradycardia and the duration of sinus pauses in symptomatic patients vary widely, since the state of systemic and regional blood flow is also significantly affected by cardiac output, total peripheral vascular resistance and vascular patency of individual basins. The most common complaints include feeling dizzy, fainting and syncope, palpitations, chest pain and shortness of breath.

When alternating tachy- and bradycardia, patients may be disturbed by palpitations, as well as dizziness and fainting during pauses after the spontaneous cessation of tachyarrhythmia.

All of these symptoms are nonspecific and transient. This circumstance, as well as the variability in the values ​​of the norm of heart rate and asymptomatic sinus pauses, sometimes makes it very difficult to establish a connection between the complaints of patients and objective signs of bradyarrhythmia, which is important for the choice of treatment tactics.

cerebral symptoms.

Patients with mild symptoms may complain of fatigue, irritability, emotional lability, and forgetfulness. In elderly patients, there may be a decrease in memory and intelligence. Pre-fainting states and fainting are possible.

With the progression of the disease and further circulatory disorders, cerebral symptoms become more pronounced.

Pre-fainting states are accompanied by the appearance of a sharp weakness, tinnitus. Fainting of a cardiac nature (Morgan-Edems-Stokes syndrome) is characterized by the absence of aura, convulsions (with the exception of cases of prolonged asystole).

The previous sensation of a slowdown in the work of the heart or its stop does not occur in all patients.

Possible cooling and blanching of the skin with a sharp drop in blood pressure, cold sweat. Fainting can be provoked by coughing, a sharp turn of the head, wearing a tight collar. Fainting ends on its own, but with a protracted nature, resuscitation may be required.

The progression of bradycardia may be accompanied by symptoms of dyscirculatory encephalopathy (appearance or intensification of dizziness, instant memory lapses, paresis, "swallowing" words, irritability, insomnia, memory loss).

Heart symptoms.

At the beginning of the disease, the patient may notice a slow or irregular pulse.

Perhaps the appearance of retrosternal pain, which is explained by hypoperfusion of the heart.

The appearance of escape rhythms can be felt as a heartbeat, interruptions in the work of the heart.

The limitation of the chronotropic reserve during exercise is manifested by weakness, shortness of breath, and chronic heart failure may develop.

In later stages, the incidence of ventricular tachycardia or fibrillation increases, which increases the risk of sudden cardiac death.

Other symptoms.

• Perhaps the development of oliguria, due to renal hypoperfusion.

  Some patients note complaints from the gastrointestinal tract, which may be caused by insufficient oxygenation of the internal organs.

  Intermittent claudication and muscle weakness were also noted.

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Diagnostics

The most constant manifestation of sick sinus syndrome is considered to be prolonged periods of bradycardia, which occur in 75% of patients with SSS. It is possible to assume the presence of sick sinus syndrome in any person with severe bradycardia of unclear etiology.

The main diagnostic method is the recording of the ECG during the onset of symptoms.

As a rule, when diagnosing sick sinus syndrome, two sequential tasks are solved. First, the function of the sinus node is evaluated (as normal or altered), and then, if deviations from the norm are detected, a differential diagnosis of the syndrome of weakness of the sinus node and autonomic dysfunction of the sinus node is carried out.

Methods for diagnosing sick sinus syndrome

• Physical examination

Holter ECG monitoring

Medical tests

Tests with physical activity

Intracardiac electrophysiological study (EPS)

Definition of clinical variants of sick sinus syndrome

In the diagnosis of sick sinus syndrome, it is important not only to identify the presence of its characteristic features, but also the definition of its clinical variant, which plays a significant role in determining treatment tactics.

Depending on the clinical manifestations, the following variants of the sick sinus syndrome are distinguished (A.V. Nedostup, A.L. Syrkin, I.V. Maevskaya):

minimal clinical manifestations.

There are no long pauses and tachyarrhythmias on the ECG. The current is relatively favorable.

Bradyarrhythmic variant.

Clinical symptoms begin to appear due to the hypokinetic state of blood circulation, up to Morgagni-Edems-Stokes attacks.

It should be noted that the bradyarrhythmic variant of atrial fibrillation may be due to disorders of atrioventricular conduction and is not in itself a diagnostic criterion for sick sinus syndrome.

Tachy-bradyarrhythmic variant:

• With a predominance of tachyarrhythmias (mainly supraventricular).

Pauses "at the entrance" to tachycardia and "at the exit" from it are characteristic.

With the same severity of tachy- and bradyarrhythmias.

Tachyarrhythmias become protracted due to the danger of their relief.

With the outcome in a constant form of atrial fibrillation (replacement rhythm).

At the same time, the bradisystolic form of atrial fibrillation is not always characteristic. Sinus node weakness syndrome is detected according to the anamnesis.

Assessment of the function of the sinus node against the background of atrial fibrillation is extremely difficult, however, the refractoriness of the AV node can be very reliably judged by the value of the minimum R-R interval.

The listed variants of the syndrome of weakness of the sinus node can be supplemented by the combined and expanded forms of the syndrome of weakness of the sinus node.

The bradycardic form of sick sinus syndrome is characterized by rigid sinus bradycardia or replacement rhythms, initially recorded mainly at night. In some patients, there is no adequate increase in heart rate during exercise.

At the initial stages of the development of the syndrome of weakness of the sinus node, these forms can occur in isolation, i.e. with a bradycardic form, a normal increase in heart rate during exercise is possible, and with chronotropic insufficiency, there may be no pronounced bradycardia at night.

In other cases (post-tachycardic form of sick sinus syndrome), only long (more than 2.5-3 s) pauses can be noted after the end of paroxysms of tachycardia or atrial fibrillation.

Sometimes the first manifestations of sick sinus syndrome are violations of sinoatrial conduction. This form of sinus node weakness syndrome is characterized by pauses with a twofold (or more) increase in the RR interval due to sinoatrial blockade. At the debut of this form of sick sinus syndrome, the automatism function may not suffer and pauses will be its only manifestation. Since initially such pauses can occur extremely rarely, it is rather difficult to diagnose this form of sick sinus syndrome in a patient who complains, for example, of rare episodes of dizziness.

The progression of sick sinus syndrome can begin with one of the four listed forms, but, as a rule, patients begin examination when they already have any combination of these mechanisms, so a fifth, combined form of sick sinus syndrome is distinguished.

Finally, the identification of the sixth, extended form of sick sinus syndrome, in the formation of which three or more “primary” electrophysiological mechanisms are involved, is determined by the need to emphasize the severity of the condition of these patients. Patients of this group, as a rule, have the longest history of clinical manifestations, and therefore, by the time of the examination, pathological changes are more pronounced than in other groups. In addition, they have exhausted compensatory mechanisms. The diagnosis of these patients is the least difficult, as well as the choice of treatment tactics (implantation of a pacemaker).

Starting with one of the "primary" forms (and possibly immediately with a combined one), the syndrome of weakness of the sinus node gradually moves to an expanded form. However, the undulating nature of the course of the syndrome is often observed, when in patients with initial manifestations they are either detected or disappear, and in patients with obvious signs of sick sinus syndrome, they are either more or less pronounced. Such fluctuations are due to the dynamics of autonomic and other influences, the response of the sinus node to them.

Depending on the nature of the development of the syndrome, it is advisable to distinguish the latent, intermittent and manifesting course of the syndrome of weakness of the sinus node:

Latent course of the syndrome of weakness of the sinus node.

With a latent course, signs of sick sinus syndrome, verified during an intracardiac electrophysiological study (EPS) (including with drug denervation), are not detected during Holter monitoring, both during multi-day and repeated 24-hour studies.

It is obvious that most patients still have clinical manifestations of sick sinus syndrome (transient disorders of consciousness), which served as the reason for EPS with medical denervation. But they are noted so rarely that it is not possible to identify them with an acceptable duration of Holter monitoring.

As a rule, the syndrome of weakness of the sinus node occurs latently, due to violations of the sinoatrial conduction.

Intermittent course of sick sinus syndrome.

The intermittent course of the syndrome of weakness of the sinus node is due to the dynamics of autonomic influences, when at the initial stages of the development of the syndrome, its manifestations are recorded only with an increase in parasympathetic and a decrease in sympathetic tone. It is with this that the registration of bradycardia at night is connected.

The fact that in patients with initial manifestations of sick sinus syndrome, its signs may not be detected every day, can be explained by slow circadian fluctuations in the body's regulatory systems or a transient increase in parasympathetic influences, for example, due to viscero-visceral reflexes.

Unfortunately, the role of the metasympathetic nervous system in the formation of the natural course of sick sinus syndrome has been little studied, although there are publications in which sick sinus syndrome is considered as "adenosine disease". Their authors associate the development of sick sinus syndrome with increased sensitivity of the sinus node to endogenous adenosine and attempt to treat the syndrome with an adenosine receptor blocker, aminophylline.

Manifesting course of sick sinus syndrome.

As it develops naturally, sick sinus syndrome becomes manifest, when its signs can be detected at each 24-hour monitoring.

But this does not exclude fluctuations in the severity of these signs, due to their intensification with an increase in parasympathetic or weakening of compensatory sympathetic influences.

These features of the course of sick sinus syndrome must be taken into account when diagnosing it, especially in cases where, based on Holter monitoring data, we “rule out” the presence of sick sinus syndrome.

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Treatment

The volume of therapy for sick sinus syndrome is determined not only by the degree of conduction disturbance, determined instrumentally, but depending on the severity of development, etiology, and severity of clinical manifestations.

Principles of treatment of sick sinus syndrome

Principles of treatment of sick sinus syndrome

Treatment of sick sinus syndrome is carried out according to the following principles:

First of all, all drugs that can contribute to impaired conduction are canceled.

In the presence of the "tachy-brady" syndrome, tactics can be more flexible: with a combination of moderate sinus bradycardia, which is not yet an indication for the installation of a permanent pacemaker, and frequent "brady-dependent" paroxysms of atrial fibrillation, in some cases, a trial appointment of Allapinin in a small dose (according to 1/2 table 3-4 times a day) followed by obligatory control during Holter monitoring.

An alternative is disopyramide.

However, over time, the progression of conduction disorders may require discontinuation of drugs, followed by the installation of a pacemaker.

While maintaining bradycardia, the simultaneous use of Belloid 1 tab. 4 times a day or Teopeka 0.3 g 1/4 tab. 2-3 times a day.

It is necessary to exclude hyperkalemia or hypothyroidism, in which the patient may be mistakenly directed to the installation of a permanent pacemaker!

If sick sinus syndrome is suspected, drugs that suppress the sinus node should be refrained from prescribing until Holter monitoring and special tests are performed.

If vegetative dysfunction of the sinus node is detected, a careful correction of the vegetative status is carried out (verapamil 120-160 mg / day in combination with belloid 1 table 4-5 times a day.

The appointment of beta-blockers in combination with cholinomimetics is not advisable.

Often, the atypical benzodiazepine Clonazepam (0.5-1 mg at night, an additional appointment of 0.5 mg in the morning or afternoon is possible) successfully corrects autonomic disorders. The drug has a nonspecific antiarrhythmic effect.

In cases of acute development of the syndrome of weakness of the sinus node, etiotropic treatment is carried out first of all.

If its inflammatory genesis is suspected, the introduction of Prednisolone 90-120 mg / in or 20-30 mg / day orally is indicated).

Emergency therapy of the SSSU itself is carried out depending on its severity:

• In cases of asystole, Morgagni-Edems-Stokes attacks, resuscitation is necessary.

  Severe sinus bradycardia, which worsens hemodynamics and/or provokes tachyarrhythmias, requires the appointment of atropine 0.5-1.0 ml of a 0.1% solution s/c up to 4-6 times a day under the control of a monitor.

  A temporary endocardial pacemaker may be placed prophylactically.

Tactics for the treatment of sick sinus syndrome

The tactics of treating sick sinus syndrome, depending on the variant of the course, may be as follows:

Observation - with minimal clinical manifestations.

Conservative therapy - with moderately pronounced manifestations of the bradyarrhythmic variant and "tachy-brady" with a predominance of tachyarrhythmias.

Installation of a permanent pacemaker.

Absolute indications for pacemaker implantation:

Morgagni-Edems-Stokes seizures in history (at least once).

Severe bradycardia (less than 40 per minute) and / or pauses for more than 3 seconds.

The sinus node function recovery time during electrophysiological examination (VVFSU) is more than 3500ms, the corrected sinus node function recovery time (KVVFSU) is more than 2300ms.

The presence of dizziness due to bradycardia, presyncopal conditions, coronary insufficiency, congestive heart failure, high systolic arterial hypertension - regardless of heart rate.

Sinus node weakness syndrome with rhythm disturbances requiring the appointment of antiarrhythmics, which is impossible in conditions of impaired conduction.

Currently, it is patients with sick sinus syndrome that make up the vast majority of patients with permanent pacemakers. It should be noted that this method, while improving the quality of life, sometimes significantly, usually does not allow to increase its duration, which is determined by the nature and severity of concomitant organic heart disease, mainly myocardial dysfunction.

When choosing a method of pacing, one should strive to ensure not only an adequate ventricular rate, but also the preservation of atrial systole.

Taking into account the available data on the ability of atrial pacing to reduce the incidence of paroxysms of atrial fibrillation and systemic thromboembolism, preference should be given to pacemakers with atrial detection and stimulation, both in isolation and with subsequent synchronous ventricular pacing (AAI-, DDD-modes).

With a decrease in the chronotropic reserve, which, like the state of atrioventricular conduction, is checked before surgery, as well as in physically active patients, the most effective is the implantation of models of pacemakers that provide increased rhythm during exercise (AAIR, DDIR or VYIR).

In patients prone to paroxysms of the bradysystolic form of atrial fibrillation, electrical cardioversion requires caution due to the risk of severe bradycardia and even asystole after it. In some of these cases, temporary pacing may be required.