Description, types, symptoms, diagnosis and treatment of heart block

Why does the violation develop?

There are many different conditions that can disrupt the conduction of an electrical impulse through the myocardium. We can not always accurately determine the cause of this phenomenon. Often, we can only guess why the blockade occurred and try to slow down the progression of the process.

In clinical cardiology, it is customary to distinguish two groups of cardiac conduction and excitability disorders:

• Cardiac, that is, caused by pathological processes occurring in the heart muscle. It can be coronary artery disease (CHD) or myocardial infarction, inflammatory diseases, cardiomyopathy. Often the source of the problem is congenital and acquired defects of the heart valves. Failure of the conduction system can be caused by tissue trauma during surgery.
• Noncardiac - the cause of such disorders lies outside the myocardium. Most often we have to deal with endocrine diseases - diabetes mellitus and thyroid gland pathology. Among the possible reasons, it is also worth highlighting hypertension, chronic bronchitis, asthma and other conditions leading to the development of hypoxia. In women, a failure is often recorded during pregnancy, with the onset of menopause.

It is important to understand: the occurrence of a blockade is not always associated with organic changes in the myocardium or serious non-cardiac diseases. Heart failure can be temporary due to stress or exercise. You can find out the nature of the violations by examining the patient.

Mechanism of occurrence

Normally, electrical impulses pass through the myocardium at a certain speed and in a strictly established sequence. The signal path begins in the auricle of the right atrium - in the sinus node. From here, excitement gradually spreads through the tissues of the atria and slows down for a short time in the atrioventricular node. Further, the impulse spreads along the branches of the His bundle, which cover the right and left ventricles. The conducting system ends with fine Purkinje fibers.

The problem arises when the conduction of the impulse is slowed down or completely blocked at a certain point. Functional and organic changes may be the cause. In the first case, the impulse reaches the cells that are in the refractory (inactive) phase - and its further passage is disrupted. The next signal can pass through tissues without obstruction. With organic changes (for example, in the case of scar formation after a heart attack), the impulse will "stumble" over the obstacle, and the failure will become persistent.

If we talk about the pathophysiology of disorders, then it should be noted the work of Na + -channels of cardiomyocytes. As long as these pathways are open, the impulse can enter the cells without hindrance. But, if the channels are inactivated, the signal conduction is slowed down or suspended. This happens, for example, in the zone of myocardial ischemia - where the blood supply to the tissues stops.

Signs of heart block are nonspecific and are not always noticeable without a special examination. You can identify the problem on the ECG. The film shows how the impulse passes through the heart muscle, whether there are obstacles to the excitation of tissues, and in which zone they are localized. Electrocardiography is the main method for diagnosing and prescribing treatment.

Possible Symptoms

Clinically, heart block is not always present. In mild disorders, the patient may not present any complaints. Failure in the functioning of the heart is detected only on the electrocardiogram.

With progressive conduction disturbances, the following symptoms occur:

• causeless weakness;
• labored breathing;
• dyspnea;
• interruptions in the work of the heart;
• slowing down the heart rate;
• dizziness.

If several impulses in a row do not pass through the tissues of the heart, loss of consciousness is possible. Over time, the disease progresses, the patient's condition worsens, and such attacks occur more often.

Types of blockages and their signs on the ECG

In cardiology, various classifications of cardiac conduction disorders are proposed. In practice, it seems convenient to us to separate all pathological processes according to the place of localization. There are such blockade options:

• Sinoatrial. The failure is localized in the area of ​​the sinus node - at the very beginning of the path of the impulse.
• Atrial. The signal flow slows down between the atria.
• Atrioventricular (AV block). The transmission of impulse between the atria and ventricles slows down or stops.
• Intraventricular. There is a failure in conducting a signal along the branches of the His bundle in the ventricles of the heart.

These conditions can be distinguished on the ECG. Typical signs of pathology are presented in the table.

Let us dwell in more detail on atrioventricular blocks. According to the clinical course, it is customary to distinguish 3 stages of the development of the process.

Heart block I degree is characterized by a slow passage of an electrical impulse from the atria to the ventricles. The ECG shows the expansion of the PQ interval to 0.2 sec. - it reflects the speed of the signal through the atria. This is the most common abnormality of AV conduction. It occurs mainly in old age against the background of organic pathology - a past heart attack, with myocarditis, heart defects.

Heart block II degree occurs with the progression of the process. Not all impulses travel to the ventricles. Changes in the ECG are determined by the type of blockade:

• Mobitz 1 AV block leads to ventricular prolapse. On the cardiogram, this can be seen from the lengthening of the PQ interval, and the changes progress with each complex. Further, only the P wave is recorded, and the QRS - a marker of the ventricles - falls out. Such symptoms are observed with a heart attack, overdose of cardiac glycosides, etc.
• AV block of the Mobitz 2 type on the ECG is indicated by a loss of QRS. The PQ interval is lengthened, but its increase does not progress. This symptom speaks of serious damage to the heart muscle and threatens the development of a complete heart block.

If the process continues to progress, several ventricular contractions in a row are blocked, and QRS complexes fall out two or more times. The patient has attacks of Morgagni-Adams-Stokes (MAS) with loss of consciousness.

Degree III disorders are complete transverse heart block. The signal does not travel from the atria to the ventricles. Separate excitement of the upper and lower parts of the heart is recorded. Changes on the ECG are chaotic, dissociation between the markers of atrial and ventricular contractions - PQ and QRS - is visible. Often this condition is combined with intraventricular blockade.

Treatment approaches

When choosing a therapy regimen, we focus on the protocols adopted by the Ministry of Health, clinical guidelines of domestic and foreign communities. Treatment should be comprehensive and rational. It is necessary not only to remove the symptom, but also to eliminate the possible cause of the problem - and to prevent the development of complications.

Moderate disturbances of intra-atrial and intraventricular conduction do not require treatment. We suggest that the patient regularly see a cardiologist, monitor his well-being, and lead a healthy lifestyle. Drug therapy is prescribed with obvious clinical symptoms - the appearance of interruptions in the work of the heart, shortness of breath, dizziness and other conditions that interfere with the usual way of life. With the development of dangerous complications, surgical treatment is indicated.

Let us dwell on the therapy of AV blockade in more detail. The treatment regimen will depend on the severity of the patient's condition. If, after the ECG diagnostics, I degree AV block is detected, therapy is not indicated. It is recommended only observation by a specialist - visits to the doctor at least once a year.

If a second degree AV block of the Mobitz type 1 is detected, treatment should be comprehensive. Antiarrhythmic drugs are prescribed to stabilize the cardiac conduction system. At the same time, the underlying disease is being treated, which caused the malfunction of the heart. No specific therapy is provided here. We select medications based on the leading symptoms and associated diseases.

AV block II degree Mobitz 2 and complete heart block are the reason for surgical treatment. A pacemaker is being implanted. The device regulates the heart rate, provides full signal transmission and uninterrupted operation of the myocardium. A pacemaker can also be offered to a patient with AV block of the Mobitz 1 type in the presence of severe symptoms.

Emergency care is indicated for the development of MAC syndrome, complete heart block. The patient must be admitted to the hospital. An indirect heart massage is performed, and drugs are prescribed to maintain a stable rhythm. The installation of a pacemaker is shown.

Lifestyle and Precautions

Treatment and prevention of cardiac dysfunction is not only medication or surgery. We recommend that the patient completely change his attitude towards life. In order to prevent the progression of the disease and avoid undesirable consequences, you should:

• Change your diet. There should be less fried, spicy and salty foods on the daily menu. It is recommended to add herbal products, focus on fresh vegetables and fruits. Fast food and fast-digesting carbohydrates are prohibited - they negatively affect metabolism and provoke the development of cardiovascular pathology.
• Do sport. Shown are aerobic exercise, yoga, swimming. If it is not possible to visit the fitness club or gym, you can walk in the fresh air every day - at least 30 minutes a day.
• Do not overexert yourself. Work "to wear and tear" will not benefit the heart. It is worth revising your daily routine. Night sleep should be at least 8 hours.
• Avoid stress. Excessive experiences negatively affect the work of all internal organs, and the heart is no exception.
• Monitor your weight. With overweight and obesity, it is worth contacting an endocrinologist to draw up a diet.
• To refuse from bad habits. Smoking is prohibited. Do not abuse alcohol.

The prognosis of the disease depends on the severity of the patient's condition. Compliance with all doctor's recommendations and timely installation of a pacemaker prolong life and preserve health.