Syndrome sick sinus (SSSU) combines in his concept of certain types of heart rhythm disorders, which are caused by pathological changes in the sinus node work. This disease is characterized by the obligatory presence of bradycardia. Often on the background pathology arise in ectopic foci of arrhythmia.
The content of the article
Along with a true syndrome of weakness of sinus node, in which occurs an organic lesion of the cells, we can distinguish 2 forms of the disease. These include autonomic function and drug dysfunction site. The last two options of the pathology are removed when you restore the functionality of the relevant Department of the nervous system or the abolition of the drugs that caused the reduction in heart rate (HR).
The disease is accompanied by weakness, dizziness or fainting. The diagnosis is exposed on the basis of electrocardiography (ECG) or Holter monitoring. For SSSU very diverse. In case of a verified diagnosis shows the installation of an artificial pacemaker (Hebrew) – permanent pacemaker.
Pathology the sinus node most likely to occur in the elderly. the Average age is 60-70 years. Research scientists from the United States showed that the disease occurs in about 0.06% of the population older than 50 years. Sex to no to disease predisposition. SSSU can manifest in childhood.
The causes of the disease
The syndrome of weakness of sinus node usually leads either organic pathology, which is responsible for structural changes in the cells or external etiologic factors. The latter leads to the violation only as a source of the cardiac rhythm. Sometimes causes SSSU are both factors simultaneously.
Organic pathology that causes SSSU:
- Degenerative disorders. The most common cause of sinus node disease is fibrosis. In this case, decreases automaticity source of rhythm and conductivity it of the nerve signal. There is evidence of a genetic predisposition to such changes. The causes of fibrosis can be:
- tumors of the heart.
- Coronary heart disease (CHD). This disease rarely causes SSSU, however, its role is large enough. Here it is as an acute ischemia (myocardial infarction) or chronic form. The main reason for the development of pathology in the sinus node in this case is insufficient blood flow:
- atherosclerosis of the right coronary artery, which feeds the node;
- thrombosis of the vessels bringing the blood to the source of the rhythm (observed in side or lower myocardial infarction).
It is for this reason heart attacks with such localization are often accompanied by bradycardia (up to 10% of cases).
- Arterial hypertension (hypertension) – chronically high blood pressure.
- Injury due to heart transplantation.
- Hypothyroidism – deficiency of thyroid hormones in the body.
External factors leading to impairment of sinus node function:
- Disruption of the autonomic nervous system:
- increased activity of the vagus nerve (causes a decrease in heart rate);
- physiological increase its tone (observed in urination, vomiting, swallowing, bowel movements, and coughing);
- in diseases of the digestive tract and urinary system of the body;
- increase of vagal tone in sepsis (infection of the blood), increased level of potassium in the blood or hypothermia.
- The effect of medicines that can reduce the function of the sinus node:
- beta-blockers (Inderal, Metoprolol);
- some calcium channel blockers (Diltiazem and Verapamil);
- cardiac glycosides (Strofantin, Digoxin);
- various antiarrhythmic drugs (Amiodarone, Sotalol, etc.)
The pathogenesis of the syndrome sick sinus
For a complete idea of the mechanism of development of the SSSU need to know and understand the anatomical and physiological characteristics of the cells of the sinus node.
The sinus node in the diagram leading system of the heart the node that is the primary heart rate source is located in the right atrium and consists of cells, regularly generating the nerve impulse. Next is the last spread in the conducting system of the myocardium, causing contraction.
Due to the fact that the sinus node is a constant source of rhythm, he is forced to work in various conditions. For example, during exercise the organs and systems of man needs a greater volume of oxygen. The heart begins to contract more often. It specifies the frequency of the sinus node. Climate variation is achieved by switching the operation of the node. Thus, some structural elements are able to generate pulses with a minimum frequency, and some are tuned for maximum heart rate.
Ischemia of the arteries that supply the sinus node or with other lesions, there is a lack of food and some cells of the node are replaced by connective tissue. Extensive loss and structural change of the source elements of rhythm isolated as a separate disease – idiopathic degeneration.
The affected centres are responsible for the minimum frequency, begin to function properly – Horny and less likely to cause bradycardia (decreased heart rate).
Clinical manifestations SSSU Initial stages of the disease is often asymptomatic. It can be even when there are pauses between contractions reaching 4 seconds.
Some patients is the shortage of blood supply to various organs, which leads to corresponding symptoms. Not always reduced heart rate leads to insufficient nutrition of tissue, because when you experience this condition included the compensatory mechanisms that promote adequate circulation.
The progression of the disease is accompanied by symptoms related to bradycardia. The most frequent manifestations of the SSSU are:
- pain in region of heart;
- shortness of breath.
The above symptoms are transient in nature, i.e., arise spontaneously and in the same way stop. The most common symptoms are:
- Cerebral. These include irritability, fatigue, memory impairment and mood swings. With the progression of the disease have loss of consciousness, tinnitus, convulsions. In addition, the SSSU is often accompanied by a decrease in blood pressure (BP), cold sweat. Over time, there are signs of dyscirculatory encephalopathy: dizziness, sharp “dips” in memory, and slurred speech.
- Cardiac (heart). The first complaints of patients presenting to the sense of irregular slow heartbeat. Due to the lack of blood heart appear painful sensations in the chest, shortness of breath develops. Perhaps the appearance of heart failure, ventricular tachycardia and fibrillation. The last two symptoms are often significantly increase the risk of sudden coronary (cardiac) death.
- Other symptoms. Among the manifestations of the SSSU, not related to circulatory disorders of the brain and heart, isolated signs of renal failure (oliguria – low urine), gastrointestinal symptoms and muscle weakness (intermittent claudication).
Due to the fact that 75 out of 100 people suffer from syndrome sick sinus, marked bradycardia, this symptom can be regarded as the main assumptions of pathology. The basis of diagnosis is the electrocardiogram (ECG) at the time of the attack. Even in the presence of marked reduction in heart rate definitely not to talk about the SSSU. Any bradycardia may be a manifestation of the violation of his autonomic functions.
Methods used to define the syndrome sick sinus:
- Monitoring of the halter.
- Drug samples and samples with physical activity.
- Intracardiac electrophysiological study.
- The definition of clinical manifestations.
Syndrome sick sinus occurs with bradycardia, displaying ECG
For choice of method of treatment it is important to determine the clinical form of disease.
- Bradiaritmicheskuyu. The main manifestations associated with impaired hemodynamics. There may be bouts of Morgagni-Edems-Stokes (due to lack of cerebral circulation). ECG is determined by the irregular rhythm with decreased heart rate. However, this symptom is not always a consequence of the SSSU. Similar electrocardiographic changes occur with the combination of atrial fibrillation with atrioventricular block.
- Tahi-bradiaritmicheskuyu. Before the attack of tachycardia and after ECG recorded pauses (increasing R-R interval). This option SSSU is characterized by a prolonged course and often becomes permanent and substitute atrial fibrillation.
- Bradycardic. In this form SSSU bradycardia with a source of rhythm in the sinus node is determined initially at night. However, there are residual rhythms. The initial stages of this variant of the disease are recognized only with the help of Holter monitoring.
- Postoyannoe. This option differs from the previous more long pauses that occur after a bout of atrial fibrillation or tachycardia.
Sometimes initial symptom SSSU is a violation of sinoatrial conduction which blocks the transmission of nerve impulses in the Atria. On ECG is clearly visible the increase in the interval P-P in two, three or more times.
The disease progresses in the form of one of the above options. Further SSSU develops in a detailed form, when any symptoms of pathology are beginning to wear a wavy character. Separately allocated three variants of the disease:
A latent option is not specified even with repeated Holter monitoring. He is diagnosed with intracardiac electrophysiological studies. For this purpose pharmacological denervation (artificial disruption of the conduction of nerve signals to the sinus node from the autonomic nervous system). This condition in most cases is observed in violation of sinoatrial conduction.
Intermittent variant is characterized by the occurrence of decrease in heart rate at night. It is associated with reduced sympathetic effect and increase in the parasympathetic function of the autonomic nervous system.
A manifestation for developing with the progression of the disease. In this case, the manifestations of the SSSU can be identified and with the help of Holter monitoring because they occur more often than once a day.
Therapy SSSU starts with dealing with all sorts of factors that in theory could lead to conduction disturbance. This first step are canceled similar drugs.
If patient has tachycardia alternating with bradycardia, but the decrease in the heart rate is not critical, then under the control Holter appoint Allapinin in minimal doses several times a day. As an alternative to drug use Disopyramide. Over time the progression of the disease immediately reduces heart rate to the minimum. In this case, the drug is canceled and implanted a pacemaker.
When deciding about the installation of the pacemaker (IVR-artificial pacemaker) is required to exclude the patient has hypothyroidism and hyperkalemia. In these States, the possible functional appearance of bradycardia.
In acute development of SSSU appropriate treatment, the causes of pathology:
- In the case of suspected inflammatory changes in the sinus node, the therapy is started with Prednisone.
- Marked reduction in heart rate with violation of hemodynamics (circulation of the entire body) is eliminated by introduction of a solution of Atropine.
- In the absence of heart beat (asystole) immediately carried out resuscitation.
- For the prevention of dangerous manifestations of the syndrome sick sinus sometimes set endocardial stimulator.
Basic principles of treatment syndrome of weakness of sinus node:
- In the case of minimal manifestations – observation.
- In moderately severe clinic shown conservative treatment with drugs aimed at prevention of manifestations.
- In severe cases, surgical therapy (implantation PSI).
A pacemaker is inserted beneath the skin under the collarbone and is associated with heart indications for the installation of permanent pacemaker:
- bradycardia less than 40 beats per minute;
- bouts of Morgagni-Edems-Stokes in history. Even in the presence of a single case of loss of consciousness;
- the pause between heartbeats for more than 3 seconds;
- the occurrence of dizziness, fainting, heart failure or high blood systolic pressure by reason of the SSSU;
- cases of violations of rhythm, in which it is impossible the appointment of antiarrhythmic drugs.
In the modern world the vast majority of people with established artificial pacemaker suffer SSSU. This method of treatment does not increase life expectancy, but significantly improves its quality.
The choice of the method of pacing is to provide not only adequate systolic function of the ventricles. To prevent the formation of blood clots and related complications is necessary to organize the normal rhythmic contraction of the Atria.
Due to the fact that the disease almost always progresses over time, symptoms patients worse. According to statistics, SSSU increases the total mortality rate of 4 — 5 %.
Accompanying pathology of the heart organic nature has an adverse effect on the General condition of the cardiovascular system. Due to the fact that frequent (about 40 – 50 %) causes of deaths are of cardiac diseases thromboembolism, forecast SSSU depends on the risk of clots in the cavities of the heart.
If sinus bradycardia without cardiac arrhythmia the risk of complications is minimal. The SSSU version with sinus pauses slightly increases the risk of blood clots. The worst prognosis in alternation of bradycardia with tachyarrhythmias. In this case, the most likely to develop thromboembolism.
Despite prescribed treatment, when SSSU sudden coronary death can occur at any time. The level of risk depends on the severity of cardiovascular diseases. In the absence of treatment, patients with syndrome of weakness of sinus node can survive any amount of time. It all depends on the form of the disease and its course.
To prevent SSSU and all diseases of the heart, lies the correct way of life and refusal of bad habits. Specific prevention is the early diagnosis of deviations in the hearts and proper prescription.
Thus, we can say that the level of life and its duration in the syndrome of weakness of sinus node depends on various factors. With the right choice of treatment the risk of coronary death can be reduced to a minimum.