Sinoauricular block ecg signs. Sinoauricular blockade

The ETIOLOGY of SA blockade largely coincides with the etiology of sick sinus syndrome (SSS) and other sinus dysfunctions - this is a degenerative calcifying lesion of intracardiac structures, numerous and varied myocardial pathology, regulatory dysfunctions (excessive vagotonia), toxic (including drug) effects. SA blockade may be one of the manifestations of SSS.

ECG DIAGNOSIS. With SA blockade of the first degree, there is a slowdown in the conduction of impulses from the SA node to the atrial myocardium. But an ECG study does not allow this to be revealed, tk. external ECG does not capture the excitation of the sinus node, and the P wave is formed by depolarization of the atrial myocardium. Sinoatrial conduction time can only be estimated using special electrocardiographic methods. There are no clinical manifestations of SA blockade of the 1st degree.

SA block II degree (incomplete SA block) is characterized by the blocking of one or more consecutive sinus impulses. This is manifested by the loss of one or more sinus cycles (P waves and RJ3 complexes). The resulting pauses can be multiples of 2, less often 3-4 basic R-R intervals, but are often interrupted by passive escape complexes or rhythms. With the clinical and electrocardiographic characteristics of CA blockade of the II degree, 2 main types are distinguished:

SA block II degree type I (Wenckenbach period in SA junction) is characterized by the loss of the sinus complex, which is preceded by a successive shortening of the RR intervals (Fig. 47). With this option, there is an increase in the time of impulse conduction from the sinus node to the atrial myocardium, progressing from cycle to cycle, culminating in the complete blocking of the next impulse. At this moment, a pause is registered, including a blocked pulse. The increase in the holding time in this periodical is maximum in its first cycles after a pause. Although the conduction progressively deteriorates in the future, the increase in this time (increment) decreases from complex to complex. In this regard, the ECG shows a gradual shortening of the PP intervals and after the shortest interval there is a pause as a result of blocking one impulse in the CA junction. This pause is shorter than twice the P-P interval preceding the pause. Classical periodicals of Wenckenbach are less common than atypical periodicals with disordered fluctuations of P-P intervals or their progressive lengthening with blocking of the next sinus impulse. With repeated Wenckenbach periods, regular ratios are established between the number of sinus impulses and P waves - 3:2, 4:3, etc. At the time of blocking the sinus impulse on the ECG, there is no next P wave and the QRS complex. Children at the time of the loss of the cardiac cycle may feel a sinking heart, sometimes accompanied by dizziness. This variant of SA block is usually benign.

SA blockade II degree II type (Mobitz blockade) is characterized by the loss of the sinus complex without changes in the RR intervals (Fig. 48). This type of blockade is manifested by long pauses as a result of the sudden blocking of one or more sinus impulses without a preceding period. Despite the absence of changes in the RR intervals in the conducted 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 fallout 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 termination of conduction in the SA connection is delayed to values ​​of 4:1, 5:1 (the pause is a multiple of the duration of 4-5 normal cycles), one speaks of a far advanced SA blockade of type II degree II. The frequent occurrence of long pauses is perceived as a sinking heart, accompanied by dizziness, loss of consciousness. Symptoms correspond to the manifestations of SSSU.

SA blockade III degree (complete SA blockade) is recognized using electrophysiological methods. On the ECG, a slow replacement rhythm is recorded (most often the rhythm of the AV junction). Clinical symptoms may be absent or signs of disorders of regional (cerebral) hemodynamics 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. With significant hemodynamic disturbances as a result of SA blockade, anticholinergics, sympathomimetics, and temporary pacing are used. With persistent SA blockade, the question of permanent pacing is raised.

More on the topic Sinoatrial (sa) blockade:

1. Sinoatrial (SA) block, or exit block from the SA node
2. The combination of a complete blockade of the right leg and a blockade of the anterior superior branching of the left leg (two-beam blockade)

All human organs and systems are interconnected. Violation of the functions of one organ immediately affects others. However, there are organs that, even if they stop working, do not pose a real threat to human health and life, since others take over their functions. And there are those that, at the slightest failure, significantly disrupt human life.

The heart is thus an indispensable organ. At the same time, any violation of its functions is reflected in every cell of the body. Many diseases can disrupt its activity. One of them is sinoatrial block, also called sinoauricular or SA block. What do these concepts mean, what is the danger of this disease, what causes contribute to its development, and can it be cured?

general description

To understand what sinoatrial A-blockade is, you should understand the anatomical features of the heart muscle. As you know, the heart is a pumping mechanism that pumps blood by contracting the heart chambers - the atria and ventricles. At the same time, the contractions themselves become possible due to electrical impulses that form in the sinoatrial or sinus node.

This component of the heart is one of the pacemakers, which is located in the right atrium. And it consists of several branches, which include the bundle of Thorel, Bachmann and Wenckebach. These branches carry electrical impulses to both atria. Sinoatrial blockade is a condition in which impulse conduction is disturbed.

Sinoatrial blockade, as a rule, occurs against the background of other cardiac pathologies, as a result of which scars and other obstacles form in the heart muscle that interfere with the conduction of the impulse. As a result, a person develops an arrhythmia, which leads to asystole. Asystole is a dangerous condition in which cardiac arrest occurs as a result of the disappearance of electrical activity.

It should be noted that sinoatrial blockade accounts for no more than 0.16% of all heart diseases. That is, the disease is quite rare, and it is diagnosed most often in men who have crossed the 50-year mark.

However, SA-blockade is also diagnosed in children. However, in childhood disruption of electrical impulses usually caused by congenital heart disease.

Reasons for the development of SA-blockade

Among the main causes of impulse conduction disturbances, the following can be noted:

• damage to the sinus node;
• violation of the propagation of an impulse along the myocardium;
• change in tone vagus nerve.

In some cases, the disease occurs due to the fact that the impulse is not formed at all, or it is so weak that myocardial cells, called cardiomyocytes, are unable to recognize it, or they are insensitive to it. It is not uncommon for an impulse to encounter obstacles in the form of scars, through which it cannot pass.

There are many factors that can provoke the development of sinoatrial blockade. These include the following pathologies:

• heart defects, both congenital and acquired;
• inflammatory processes in the myocardium;
• systemic connective tissue diseases;
• tissue damage to the heart oncological diseases or injury;
• coronary heart disease that develops against the background of cardiosclerosis, or is a consequence of myocardial infarction;
• myocardial infarction, causing the death of a section of the heart muscle;
• cardiomyopathy;
• some types of VSD;
• intoxication of the body caused by an overdose of certain drugs or their intolerance, as well as poisoning with various chemicals.

The function of the sinus node is directly affected by the vagus nerve. Sinoatrial blockade can occur when its activity changes. However, in this case, as a rule, it does not pose a serious threat to human life, since it is able to pass without medical intervention.

Types of SA blockade and symptoms

Based on the severity of arrhythmia, sinoatrial blockade is divided into several degrees:

• 1 degree;
• 2 degree;
• 3 degree.

1st degree SA block

In this case, they speak of incomplete SA blockade, when the sinus node functions smoothly, and the impulses cause myocardial contractions in the atria. However, with such a pathology, the heart muscle receives impulses somewhat less frequently than necessary. At the same time, sick people do not feel any manifestations of the disease, and no changes are recorded during the ECG.

The presence of SA-blockade of the 1st degree can be suspected by the only sign - bradycardia. And it is possible to diagnose it only with an electrophysiological study of the heart.

2nd degree SA block

A distinctive feature of sinoatrial blockade of the 2nd degree is that the formation of impulses does not always occur. As a result, in some cases, there are no myocardial contractions, which is recorded on the ECG.

This pathology is divided into two types:

• SA-blockade of the second degree of type 1;
• Type 2 second-degree SA block.

In the first case, the conduction of impulses decreases gradually. In this case, the patient is concerned about the following symptoms:

• dizziness;
• general weakness;
• pre-fainting states;
• short-term loss of consciousness.

Loss of consciousness can be provoked by any physical exertion, as well as turning the head or coughing.

In the second case, there is a persistent violation heart rate, accompanied by pauses, during which sick people feel weak and often lose consciousness.

3rd degree SA block

This pathology poses the greatest danger, since the flow of impulses from the sinus node stops, which means that myocardial contraction does not occur. Sinoatrial blockade of the 3rd degree is very often accompanied by loss of consciousness, requiring resuscitation.

Signs of SA blockade in children

In children, pathology can be suspected by signs similar to adults. Most often, the reason for going to the doctor is the child's rapid fatigue and fainting, accompanied by a blue nasolabial triangle.

Sinoauricular block on ECG

Electrocardiography of the heart is the main way to help diagnose a violation of the conduction of electrical impulses. However, its implementation is not effective in the case of sinoauricular blockade of the 1st degree. The only signs of pathology in this case are bradycardia, to which a person adapts, and a shortening of the PQ interval.

At 2 degrees of pathology, the following deviations are recorded on the ECG:

• the P-P index decreases, indicating a lengthening of the interval between atrial contractions;
• after pauses, there is a gradual reduction in the time of the P-P indicator;
• one of the next PQRST complexes may be absent;
• during pauses, impulses come from other pacemakers;
• if there are several contractions, the duration of the pause is several P-P.

At the 3rd degree of pathology, an isoline is recorded on the ECG, indicating the absence of electrical impulses and myocardial contractions. During this period, the likelihood of death increases many times over.

Diagnosis of the disease

The main methods for diagnosing violations of the electrical conduction of the heart are the following studies:

• Holter ECG.

The Holter ECG is effective if the traditional electrocardiographic examination of the heart did not reveal any changes. Holter monitoring is carried out for 3 days, which allows you to reliably assess the violations in the sinus node. This type of study is also indicated for children.

Another diagnostic method is a test with atropine. The presence of pathology can be said if, after the introduction of this substance, the patient's pulse first increases and then sharply decreases, which will become indirect evidence of the blockade.

Finding the cause of the dysfunction of the sinus node helps ultrasound procedure hearts. This type of study allows you to detect defects, scars and other pathological changes in the structure of the myocardium.

Treatment of the disease

Sinoatrial blockade of the 1st degree does not require special therapy. In most cases, the treatment of the disease that caused its violation helps to normalize the heart rhythm. If the violation of the sinus node was caused by taking any medications, they are canceled.

If the cause of the disease was a change in the activity of the vagus nerve, patients are prescribed drugs based on atropine. The same drugs are also prescribed for children with VVD, which caused a violation of myocardial conduction.

Nitroglycerin, Atropine, Platifillin and Nidefilin help relieve severe attacks of arrhythmia. However, drug therapy in this case brings only temporary relief. In especially severe cases, patients are shown the installation of a pacemaker.

All patients, regardless of the severity of the disease, are prescribed drugs that improve metabolic processes in the myocardium and its contractility.

Children, in addition to taking medications, are advised to reduce their workload, reduce the intensity of sports activities, and in some cases refuse to visit children's institutions altogether. However, if the arrhythmia is transient and there is no risk to life, children are not recommended to be isolated. In this case, you only need to visit a doctor regularly and undergo the necessary studies.

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

1st degree SA block: indistinguishable on the surface ECG.

SA block II degree:
Type I: gradual shortening of the PR interval leading to prolapse of the P wave and QRS complex
Type II: repeated prolapse of P waves and QRS complexes

3rd degree SA block: consecutive loss of several P waves and QRS complexes at once

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

I. SA-blockade of the first degree

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

II. SA block II degree

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

SA block II degree, type II. Characteristically appearing sometimes loss of sinoatrial conduction. On the ECG, this is manifested by the loss of the P wave and the corresponding QRS complex.

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

III. 3rd degree SA block (complete SA block)

Third-degree sinoatrial block is also called complete SA block. In the analysis, there is a loss for some time of the P wave and the QRS complex; during this period of time, circulatory arrest occurs. Characteristic of SA-blockade of the III degree is the intermittent appearance of pauses after the loss of the sinus complex, i.e. short ventricular asystole. This is due to complaints of patients on dizziness. In these cases, implantation of a pacemaker is also indicated.

Sinus arrest is often indistinguishable from complete SA block.

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

Video lesson of sinoatrial blockade on the ECG (SA blockade)