Heart block: complete and partial, various localizations - causes, signs, treatment. Atrioventricular block Ventricular block

Egilok, a drug produced in Hungary, is becoming increasingly popular among hypertensive patients. Having a blood pressure-lowering effect, at the same time egilok alleviates the condition of those affected by complications of hypertension and atherosclerosis of the heart. The drug also helps with diseases not directly related to high blood pressure. Many patients prefer Egilok, ignoring analogues, of which there are many. What motivates them to make a particular choice?

Instructions for use

The name “egilok” is the trademark given to the medicine by the manufacturer (Hungary). There is also Indian egilok.

Egilok's INN is metoprolol. This is the main active ingredient, supplemented by auxiliary ingredients: anhydrous colloidal silicon dioxide, microcrystalline cellulose, magnesium stearate, sodium carboxymethyl starch and povidone. Dosage form: tablets.

Auxiliary components serve to preserve the base (active ingredient - metoprolol tartrate) until use. They serve as enterosorbents, emulsifiers, fillers, and stabilizers. The components are arranged in such a way that they ensure the stability of the composition and the safety of the medicine. Once in the body, they help the main component fully exhibit the desired effect.

In Latin, egilok is Egilok, and according to the active principle it is designated: Metoprolol tartat, if this is a fast-acting form. Extended-release egilok retard contains another metoprolol compound – succinate. Accordingly: Metoprolol succinate.

Tablets are dosed in milligrams of the active substance, three types of dosage: 25, 50, 100 mg. All of them are white or close to white, biconvex. On tablets of a lower (25 mg) dosage, the surface is marked with a cross-shaped notch. This makes it easier to split (break) the tablet when even smaller doses are needed. Usually, at the beginning of taking the drug, when the optimal dosage is being selected, this is necessary.

Large dosage tablets have risks that help them break neatly. The tableted drug has no odor.

Pharmacological group, mechanism of action

Pharmacotherapeutic group of Egilok: beta1-blockers. Egilok is a cardioselective drug that targets the myocardium and the coronary vessels that supply it.

Selective beta1-blockers at a reasonable dosage work only with beta1-adrenergic receptors, blocking only them. Another type, responsible for breathing, gestation of the fetus, peripheral vessels - β2-adrenergic receptors - calmly continues to work, the egilok is not directed at them. The medicine purposefully moves towards its intended target, finding the receptors for which it was created. By binding to them, egilok does not allow catecholamines to produce a strong shake-up in the body under provoking factors:

1. Emotional stress;
2. Increased physical activity;
3. Sudden changes in weather (almost 100% of “vascular” patients react to this by worsening their condition).

The sympathetic system, under the influence of egilok, reduces activity towards the myocardium. Egilok, by blocking β1-adrenergic receptors, slows down the pulse, reduces four important values ​​at once: heart rate, cardiac output, force of contractility and blood pressure numbers.

When beta1-adrenergic receptors are blocked, the heart works calmly. Its blood filling is carried out more completely and without overload, at the moment of relaxation (diastole phase) of the ventricles. The group's medicines are a lucky find for pharmacists. Egilok (metoprolol) is a typical representative of a number of beta-blockers.

The problem for patients with high blood pressure is left ventricular dysfunction, enlargement of the ventricle due to excess load (blood pressure) on it. Regular long-term use of Egilok allows you to reverse this pathology. The ventricle, without experiencing overload, changes size: it returns closer to normal.

Normalizing the size and function of the left ventricle and restoring the time needed for rest (diastole) has a direct impact on patient survival. Mortality from vascular accidents, especially in men, is significantly reduced. This is why Egilok tablets are taken: to prevent such misfortunes as heart attacks, strokes, and cases of sudden death. If hypertension is moderate, “mild,” then the therapeutic effect is more pronounced.

The need of the heart muscle for oxygen supply with blood decreases, and blood supply increases. The preload on the heart is reduced; it does not have to make as much effort to pump blood as before taking the medicine. Oxygen is absorbed better than what happened at high heart rate and pressure.

The selectivity of Egilok is an advantage over non-selective drugs of the same group. It has almost no spasmodic effect (with adequate doses) on the respiratory muscles (bronchi), as well as on the smooth muscles of the walls of peripheral vessels. It also does not affect tissues of muscles not included in the myocardial zone. It works only cardiologically, with a positive effect.

Egilok is good for diabetics: without affecting metabolic processes, it does not provoke hypoglycemia. Insulin secretion does not depend on the presence of metoprolol (egilok) in the blood. Cholesterol levels with prolonged therapy with Egilok are significantly reduced.

Pharmacokinetics

Absorption of the active substance after passing through the metabolic barrier of the liver occurs quickly. The process improves with an increase in the percentage of bioavailability if egilok tablets, according to the instructions for its use, are consumed with food. The liver controls everything entering the gastrointestinal tract, so it is easier to “slip” it unchanged through the gastrointestinal tract with food. It becomes 40% more accessible to the body than taken on an empty stomach. Metabolites lose the therapeutic activity of egilok.

The percentage of binding of metoprolol to blood proteins varies. It is small with a healthy liver, but reaches 10% with liver pathology.

The drug is eliminated by the kidneys. It may slow down if you have kidney failure, but this does not cause significant harm.

Indications for use

For egilok, the indications for its use are similar to the use of other beta-blockers. What these tablets are prescribed for can be understood by studying the mechanism of action of egilok. The drug is used for:

• Hypertension of all stages (arterial hypertension) - monotherapy or as a component in a complex of drugs;
• Cardiac ischemia;
• Tachyarrhythmias (tachycardias) of inorganic origin are functional reversible malfunctions of the myocardium;
• Arrhythmias with organic causes: supraventricular, paroxysmal tachycardia, atrial, ventricular, supraventricular extrasystole;
• Angina pectoris, stable course;
• Prevention of exacerbation of migraine, prevention of painful attacks;
• Hyperthyroidism (symptom relief, addition of specific therapeutic methods);
• Angina pectoris complicated by a heart attack is included in the complex of basic therapeutic measures. Treatment of the post-infarction state, simultaneous prevention of recurrence, prevention of a new heart attack.

Hypertonic disease

The instructions for use indicate at what pressure Egilok is effective. It is prescribed for any stage of this disease. If blood pressure levels are slightly higher than normal, one drug may help (monotherapy). Then the instructions for use provide a minimum - 25 mg of egilok per dose may already be enough.

Cardiac ischemia

Ischemia – narrowing, infringement. In fact, there is no infringement, there is a strong narrowing of the feeding arteries. In acute cases, and - their blockage, closure of the lumen with atherosclerosis (plaques come off), thrombosis (blockage of a vessel with a blood clot). When the lumen of the vessels is narrowed, the nutrition of the myocardium is inevitably disrupted. Egilok relaxes blood vessels, facilitating the passage of blood through them to the myocardium. IHD is a form of angina “with experience”, its dangerous phase. By improving the blood supply and nutrition of the heart, egilok helps it survive.

This happens with neuroses, in those suffering from dystonia, other disorders of the nervous system or cardiovascular system. Among the whole range of symptoms, tachycardia often comes out ahead of the rest. It worries more, creates fear, intensifies itself and intensifies the rest of the symptoms. There is no better remedy than beta blockers. Egilok will calm down a rapid pulse and, having some anxiolytic and anti-anxiety effect, will calm a person. At the same time, other unpleasant symptoms will go away: fear, sweating, tremors. Even for a heart that does not have organic changes, such an anxious state is not beneficial. The drug will help return everything to normal.

Arithymia of organic origin

Complex, severe rhythm disturbances. Caused by various reasons: atherosclerosis, impaired conduction of myocardial impulses, pathology of the sinus node. Beta blockers regulate the rhythm during tachycardia (reduce heart rate). Some types of ecstasystole are amenable to egilok, the rhythm is evened out. Or the extrasystoles at least become less frequent and acquire a sinus rhythm instead of an erratic one. The medicine egilok is sometimes used even for implicit bradycardia - for health reasons. Special caution is needed here, but the patient’s life must be saved. Even Egilok 25 may turn out to be an excess, it is divided, and initially dosed with a quarter of such a tablet. And this small dose will still have the desired effect. Almost without slowing down the pulse contractions.

The instructions for use list bradycardia as a contraindication for Egilok, but reviews from practicing cardiologists indicate: sometimes, in the smallest doses, it is necessary. Grind (again contrary to the instructions), directly under the tongue - for speed of action. This will save lives in an acute situation, and the selection of other drugs will come later.

If the heart rate allows (not too low), beta blockers help with this diagnosis. Attacks of angina pectoris, it is not for nothing that it is named with the addition of the word “stress,” occur during physical or mental stress. Egilok, taken constantly, relieves stress. Attacks become rare and mild.

Migraine, attack prevention

The disease is common, but little studied. The culprit of pain today is considered to be dilatation (expansion) of cerebral vessels due to their overflow with blood and increased pressure.

By lowering blood pressure, egilok warns and blocks dilatation.

Additionally, it has an anti-anxiety effect: it has been noted that migraine attacks are a frequent occurrence in anxious people. No anxiety - no migraine.

Hyperthyroidism

The disease cannot be treated with beta blockers. But they are used for an auxiliary purpose. Egilok will help reduce the rapid pulse characteristic of the disease. At the same time, the intensity of sweating, tremor, and blood pressure decrease. The symptoms of hyperthyroidism are smoothed out, this is important for the patient’s well-being.

Prevention of recurrent heart attacks

The drug, in combination with others, helps protect a person from the risk of a recurrence of a heart attack. A weakened heart may not be able to withstand a second heart attack. Here the role of medications and the doctor’s ability to navigate their selection and development of treatment tactics are vitally important.

Now you know what egilok helps with. It's time to find out when it's not shown. Contraindications to taking Egilok are:

Use with caution

• Pheochromocytoma – combination with alpha-blockers is necessary; without them, Egilok is not used.
• Diabetes mellitus has a dose-dependent effect; at high doses, stimulation of hypoglycemia cannot be ruled out.
• Metabolic acidosis - interference with the failure of metabolic processes by a beta-blocker may be observed with an unpredictable result.
• Bronchial asthma - a slight effect on the second type of receptors that control the respiratory system - β2-adrenergic receptors - occurs occasionally in sensitive, asthmatic patients.
• Psoriasis.
• Obliterating endarteritis, pathology of peripheral vessels.
• Failure - renal, hepatic: possible clearance problems, delayed elimination, increased concentration of the drug above the recommended level in the body.
• Depression is a stage of exacerbation or remission.
• Tendency to allergies - if it is necessary to administer anti-shock drugs (adrenaline), the body may not respond to them under the influence of egilok.
• Hyperthyroidism (thyrotoxicosis) - increased hormonal activity of the thyroid gland affected by the disease requires careful selection of drugs and doses, even for symptomatic treatment.
• COPD - severe lung disease makes the respiratory system sensitive even to almost neutral selective beta blockers. The cardioselectivity of Egilok does not exclude micro-influences on other systems. If they are impaired by disease, special control is required.

Pregnancy, lactation

If both are at risk: the mother from stopping Egilok, the fetus from using it, doctors compare the risks. If possible, a drug that is gentle on the baby is selected for the pregnant woman. If such a possibility is excluded, and it is egilok that is needed (for health reasons), they try to save both. The effect of the drug on the developing organism is carefully monitored.

The newborn is immediately examined, checked for possible pathological deviations of systems and organs.

If there are any, intensive therapy is carried out, trying to correct the negative effect of the drug received in utero.

The child may be under observation for a long time.

Directions for use, dosage

Take the drug without strictly linking the time of administration with food. There is no need to wait minutes before or after eating. You can - right along with food, it will be absorbed even better. The daily dose of egilok is divided according to the instructions in the instructions into two doses - morning and evening. The minimum is set based on the condition and concomitant diseases. Start with small doses. Through gradual selection they reach the optimal one. At each such increasing “step” they stay for up to two weeks to check the effectiveness.

Daily maximum: 200 mg, no more should be taken, the risk of side effects will increase. If the recommended daily dose is exceeded, the selectivity of egilok is partially lost. The active substance may begin to block both types of adrenergic receptors, which should not be allowed. The doctor's prescriptions should be carried out scrupulously: he knows how much to prescribe and takes into account all the features of the drug.

The dosage of Egilok can and should vary depending on the type of disease. There may be the same doses for some diagnoses.

Hypertonic disease

The dosage of Egilok varies from the initial dose of 25 mg to the maximum dose of 200 mg. The selection is individual, stepwise. Reception according to the scheme: morning + evening, the dose is divided in half. They settle on the most comfortable dose that provides the expected effect. Arterial hypertension, detected in time, at the onset stage, can be corrected with Egilok monotherapy. If the disease persists and blood pressure levels are high, well-combined drugs from other groups that lower blood pressure are added.

Cardiac ischemia

Start with 25 or 50 mg, depending on the patient’s condition and overall tolerance to the medication. For ischemic heart disease, this dosage is taken twice or three times a day. The daily dose can be increased to 200 mg. If such an amount is poorly tolerated, and a smaller amount does not give the desired effect, leave it in a normally tolerated amount. The treatment is adjusted by adding another medicine that complements Egilok, which alleviates the patient’s condition.

Functional tachyarrhythmia

Prescription: morning and evening – 50 mg each. If the effect is insufficient - 100 mg. Monotherapy usually works well.

Extrasystole, tachycardia

Start with 25 or 50 mg. Frequency of administration: three times a day. If it is well tolerated but has little effectiveness, the dose is increased. Do not exceed the maximum level - 200 mg. You can practice combined treatment of arrhythmias. It’s better to start – stationary.

Stable exertional angina

The treatment regimen is similar to the treatment of ischemic heart disease, since ischemic heart disease is formed during the progression of angina pectoris and is one of its stages.

Preventing migraine attacks

Dose selection is individual. Usually it is 100 mg, divided into two doses. Or - the maximum daily dose of two hundred milligrams. Also divided in half, taken twice (morning + evening).

If migraine attacks are rare, continuous use is not practiced. The approach of an attack is characterized by precursors (decreased vision, flashing of bright spots before the eyes). When such precursors are present, immediately take Egilok in a pre-selected dose. Continue for several days.

Hyperthyroidism

Up to four doses per day. The maximum daily dose or close to it (150 – 100 mg).
Prevention of recurrent heart attacks. The maximum or half daily dose of the drug (200 or 100 mg). Divided into two, reception: morning and evening.

Side effects

Egilok has side effects, which is understandable: the medicine, even with its selectivity, is in the systemic circulation. Organisms are different, so is reactivity. What is useful for most is not suitable for everyone. Undesirable effects from taking Egilok:

• Headache, dizziness;
• Inhibition or activation of nervous processes: from excessive excitability to severe fatigue;
• Sexual dysfunction – decreased libido/potency;
• Amnestic-confabulatory syndrome (memory problems);
• Increased unmotivated anxiety;
• Bradycardia;
• Feeling of cold feet;
• Depression;

• Drying of the mucous membranes of the mouth;
• Insomnia or drowsiness;
• Symptomatic exacerbation of heart failure;
• Orthostatic hypotension;
• Hallucinations;
• Diarrhea;
• Painful heartbeat;
• Cardiogenic shock;
• Nausea;
• Liver failure;
• Arrhythmia;
• Abdominal pain,
• Cardiac conduction disturbances;
• Constipation;

• Gangrene (due to worsening peripheral circulatory disorders);
• Vomit;
• Tinnitus;
• Thrombocytopenia;
• Conjunctivitis;
• Distortion of taste perception;
• Decreased vision;
• Rhinitis;
• Alopecia;
• Bronchospasm;
• Irritation of the mucous membranes of the eyes;
• Photosensitivity;
• Shortness of breath on exertion;
• Hives;
• Arthralgia;
• Heavy sweating;
• Increased weight gain.

Overdose

Exceeding the dose of egilok causes dose-dependent effects. An overdose can be determined by symptoms:

1. Sinus bradycardia;
2. Arterial hypotension – severe, low levels, complications including stroke;
3. Acute heart failure;
4. Blockade of myocardial sections (atrioventricular);
5. Bronchospasm;
6. Hypoglycemia;
7. Blueness (cyanosis) of the skin;
8. Unconscious state;
9. Falling into a coma.

An overdose of Egilok during therapy with blood pressure-lowering drugs, taking barbiurates, or in the presence of ethanol in the body is more dangerous. Symptoms intensify, the prognosis worsens.

Before the ambulance arrives, if consciousness is preserved, you can give an enterosorbent and try to induce vomiting.

Drug interactions

Concomitant use with antihypertensive drugs causes an additive effect. Combination therapy is prescribed, started and monitored by a doctor. The overall effect is the goal of such treatment, but it should not be excessive. Excessive doses are dangerous due to hypotension, which can cause a number of complications. Some of them are more dangerous than high blood pressure.

It is risky to combine Egilok and other beta blockers with calcium channel blockers (slow). Intravenous use of verapamil is especially dangerous; there is a risk of asystole (cardiac arrest).

Antiarrhythmics taken orally (cordarone, quinine) can provoke atrioventricular block. Severe bradycardia cannot be ruled out.

Do not combine Egilok with cardiac glycosides: the conductive function of the heart may be affected and severe bradycardia may develop.

Clonidine, reserpine, and some other antihypertensive drugs are not combined with egilok, a representative of beta-blockers. The situation is fraught with hypotension and bradycardia.

If clonidine is still taken with egilok, long-term use of clonidine is not currently practiced. It is impossible to cancel drugs at the same time. The order is as follows: first stop taking metoprolol (egilok). Clonidine remains “on the drug menu” for several more days. Then it is cancelled. If you do otherwise, remove clonidine first, there is a high probability of two consequences. The development of a hypertensive crisis and the formation of drug dependence occur.

CNS depressants (neuroleptics, tranquilizers, ethanol and other substances of similar action) together with egilok can cause critical hypotension. Emergency recovery measures will be required. And if someone taking a beta blocker is given anesthesia, there is a risk of asystole.

Do not combine alpha and beta sympathomimetics with Egilok (severe hypotension, clinically significant bradycardia, high risk of cardiac arrest).

Ergotamine has a vasoconstrictor effect; a beta blocker cannot resist it in this combination.

Egilok has many incompatibilities with medications. NSAIDs – anti-inflammatory drugs of this type reduce its effectiveness.

Antihyperglycemic agents and insulin increase their activity when paired with Egilok (risk of hypoglycemia).

Inhibitors of various enzymes and neurotransmitters - the effect of the drug is enhanced by increasing its concentration in the body.

Barbiurates and other enzyme inducers inhibit metoprolol, and the effect of egilok weakens.

If substances that block the nodes (ganglia) of the sympathetic nervous system (nervous system) and drugs of the same group with egilok (beta-blockers) are used, even when these are eye drops, special control is needed. The body's reactions to these combinations are unpredictable.

special instructions

Analogues

The medicine is effective, common, and necessary for many people. Egilok has many analogues in the country and around the world. Most are given a name that matches the active substance, some are named after the companies that produce them. The price of Egilok is not the lowest, nor is it low: for thirty 100 mg tablets the patient will pay 130 - 150 rubles. You can buy a cheap analogue of Egilok, the instructions, composition, properties are the same: metoprolol (after agreeing on a replacement with your doctor) - German, the same packaging - 55 rubles.

The most famous analogues are:

• Metoprolol: Russia, Poland;
• Lidalok: Russia;
• Metoprolol Teva: Israel;
• Metolol: Russia;
• Metoprolol ratiopharm: Germany;
• Emzok: Germany;
• Metoprolol organic: Russia;
• Metoprolol zentiva: Slovenia;
• Egilok Retard (extended): Switzerland, Hungary;
• Metoprolol-Obl: Russia;
• Metoprolol succinate: India;
• Metozok: Russia;
• Metokor adifarm: Bulgaria;
• Metoprolol tartrate: Ukraine;
• Corvitol 50: Germany;
• Betaloc, Betaloc ZOK (extended): Sweden, France;
• Metocard: Russia, Poland;
• Metoprolol-acri: Russia;
• Vasocardin: Slovenia;
• Betalok: Sweden;
• Egilok S (extended): Hungary;
• Serdol: Romania;
• Egilok: Hungary.

Dispensation by prescription.

Disturbances in the passage of the impulse between the sinoatrial node and the beginning of the branching of the His bundle, which is called heart block, cause disruption of the heart rhythm and decreased blood supply to the brain.

Heart block, in which the passage of the excitation impulse slows down, is considered partial. If the impulse ceases to be transmitted completely, then complete heart block is formed.

When a partial blockade occurs, most patients feel quite healthy, attributing a slight malaise to fatigue after a hard day at work, stress, etc., since they do not feel significant disturbances in cardiac activity. In many cases, it is not detected during the next preventive examination or when seeking medical help. At the same time, the word “blockade” causes panic among many. So what kind of disease is this, and what danger does it pose to humans? Let's try to explain.

What is heart block?

Let's start with the fact that the normal functioning of the heart is facilitated by electrical impulses generated in the sinoatrial node. From it they are distributed throughout the atria, the contractions of which contribute to the transmission of the impulse further, through the atrioventricular node to the atrioventricular His bundle. From there it is distributed into areas through smaller branches. With a decrease in the automaticity of the sinus node the passage of the impulse slows down, the interval increases (lengthens) between atrioventricular contractions.

Sometimes the impulse does not travel through the conduction system at all. In this case, there is no contraction of the atria or ventricles. A long pause occurs (atrial), which is called the Wenckebach period. When it occurs, conductivity is restored again, thanks to the ectopic rhythm, which is called the “rescuing” rhythm. And the next atrioventricular interval is already of normal length. Symptoms with incomplete (partial) heart block are almost completely absent, since it does not disrupt the blood supply to the brain. More often partial heart block is accompanied by slight dizziness and slight malaise.

Complete heart block is characterized by the occurrence of bradysystole - a sharp decrease in the number of ventricular contractions (up to 30-40), when the number of atrial contractions remains normal. This almost always causes significant circulatory problems. Patients complain of shortness of breath, dizziness, and their vision suddenly becomes dark.

Sometimes a drop in cardiac activity (a sharp decrease in ventricular contractions to 15 per minute) causes. In this case, epileptiform convulsions develop, and the person loses consciousness for several minutes. Before it occurs, he begins to feel weak, a feeling of intense heat arises in his head, then he suddenly turns pale and loses consciousness. This condition is called instantaneous blockade. It develops when a violation of sinus rhythm turns into ventricular automaticity. Repeated attacks of MAS often cause death.

Video: heart block on ECG

The video shows an intermittent (alternating) blockade of either the right or left bundle branch

Heart blockades - briefly about the types

The following types of blockade are distinguished depending on where the obstacles that arise that cause disruption of the impulse patency are localized.

Sinoatrial blockade

Usually calls excessive stimulation of the vagus nerve, or organic damage to the sinus node. It is characteristic of the area between the atria and the sinoatrial node, accompanied by loss of complete heartbeat, which is detected by auscultation (listening). The nature of the loss is irregular.

Sinoatrial blockades also develop under the influence of potassium and quinidine drugs prescribed for the treatment of heart disease. It also occurs in people in excellent health who engage in various sports when their physical activity increases.
Partial (incomplete) blockade, associated with a decrease in the activity of the sinoatrial node, is asymptomatic. No treatment is required for this type of blockage. In cases of significant pain caused by increased excitability of the vagus nerve, a course of therapy with atropine administered subcutaneously is carried out; sympathomimetics can be used.

Intraatrial block

When it occurs the patency of excitation is disrupted inside the atria.

Atrioventricular block

The cause is pathology of the passage of the impulse that excites the ventricles simultaneously through all three branches of the His bundle. They are divided according to degrees, which determine the severity of the disease.

1st degree

First degree heart block occurs when there is a delay in the passage of the electrical impulse through the atrioventricular region. It is detected only through an ECG. If cardiac activity is normal, the duration of the interval of impulse passage from the atria to the ventricles (P - Q) is 0.18 s. When a 1st degree blockade develops, the impulse conduction interval (P – Q) increases to 0.3 s and higher.

2nd degree

A 2nd degree block is characterized by a further increase in conduction disturbances in the atrioventricular node. This disorder has three types (Mobitz).

3rd degree

With the 3rd degree of blockade, the transmission of impulses in the atrioventricular node stops completely. And they begin to contract spontaneously, regardless of each other. Myocardial pathologies, drug intoxication and other factors lead to the development of complete blockade.

Intraventricular block

Associated with the formation of pathology of the pathways located below the atrioventricular node: in one or more of its legs. With this type of blockade, the exciting impulse directed to the ventricles is delayed or not transmitted at all.

types of intraventricular blocks

Video: Lesson on Heart Blocks

Etiology

• Basically, the causes of heart block lie in the progression of diseases, such as:
  1. myocarditis of thyrotoxic, diphtheria or autoimmune type;
  2. diffuse connective tissue diseases;
  3. and heart tumors;
  4. sarcodia and amyloidosis;
  5. myxedema;
  6. syphilis affecting the heart and myocardial defects caused by;
  7. myocardial infarction or.
• No less common causes are drug poisoning caused by exceeding the dosage of certain drugs: quinidine (against arrhythmia), Corinfar, verapamil, digitalis and a number of others. Digitalis preparations are especially dangerous for heart blockades of any kind.
• Incomplete blockade often occurs in completely healthy people. Most often it is caused by overexcitation of the vagus nerve, which is caused by increased stress during training or physical work.
• There have been cases of congenital blockade that occurs as a result of pathology of intrauterine development. In this case, newborns are diagnosed with heart defects, etc.
• Blockade can also be caused by certain types of surgical interventions used to eliminate various heart defects and other anomalies.

Blockades of intraventricular localization

The most common is intraventricular heart block. It has several varieties, which are classified based on which branch of the His bundle the pathology arose. The mechanism by which the excitatory impulse is transmitted to the ventricles from the atria includes three branching segments. They are called the legs of His. First there is a branch to the RV (right ventricle). It is called the bundle branch (right). Next comes the left segment (leg), which is directed downward. Being a continuation of the main trunk, it is thicker than the others. Just below the segment branching to the pancreas, the left segment divides into posterior and anterior branches. Along the posterior branch, excitation is transmitted to the septum, and along the anterior branch - directly to the ventricle, located on the left side.

Damage to any branch of the His bundle contributes to the formation of a single-bundle block. If conduction is impaired in two branches, then we are talking about a two-bundle blockade. If the pathology develops in all three legs (complete bundle lesion), this means the occurrence of a complete three-bundle transverse block of the atrioventricular (distal) type.

Based on the location of the conduction pathology, there is a division into right ventricular and left ventricular blockades. If conduction pathology occurs along the anterior or posterior part of the left segment of the His bundle, a blockade of the left ventricle of the heart is formed.

1. Pathology of the conduction of the anterosuperior left leg mainly progresses with the development of diseases leading to. This may be myocarditis, anomalies of the interventricular septum, aortic heart disease, heart attack, etc. There is a violation of the patency of the excitation along the anterior section of its side wall. It is distributed abnormally, starting from the lower areas and gradually rising upward. That is, the septum between the ventricles is first excited, then the impulse is transmitted to the lower portion of the posterior wall. At the end of the period, along the anastomoses, the excitation reaches the anterior section of the lateral wall. The cardiogram shows that the QRS interval is wider than during the normal passage of the impulse by 0.02 s. The R wave is of greater height, and the S wave is of greater depth. At the same time, abnormal Q waves are formed.
2. When excitation completely ceases to be transmitted through the His bundle (along its left leg), a complete left ventricular block occurs. But along the segment on the right side the impulse passes in a normal rhythm. And only after excitation occurs in the right part of the septum and RV, the impulse is sent to the left ventricle. Conduction disorders of this type are caused by severe heart diseases, which give complications in the form of various defects of the myocardium and impulse-conducting system.
3. When the left ventricular block is incomplete, the passage of the electrical impulse to the branching slows down. It is brought to the LV transseptally, in a retrograde direction (from left to right) along the right branch of the His bundle, starting from the RV.

The development of blockade of the right ventricle in most cases is caused by diseases leading to its overstrain and the formation of wall thickening. Anomalies of this type are often caused by intoxication of the body with medications prescribed to eliminate disturbances in the functioning of the heart (beta blockers, quinidine, etc.). RV block very often develops in people whose hearts are completely healthy. The anomaly in the patency of the impulse in this case lies in the fact that the septum and LV are first excited, and only then the impulse is transmitted to the RV.

From the above the following conclusion follows: The pathology of the passage of the excitation impulse at any of the branches of the His bundle is a partial blockade of one of the ventricles, on the side of which a pathological interruption of the branch occurred. Excitation to the blocked ventricle is transmitted in an abnormal “bypass” way: through the septum and the ventricle corresponding to the normally functioning branch.

Intraventricular blockades can be identified mainly by electrocardiographic examination. The cardiogram shows a deviation of the electrical axis to the left by an angle of up to 90° with a negative value in case of left ventricular block caused by conduction disturbances in the anterior segment. Deviation of the electrical axis to the right by an angle of up to 90° with a positive value indicates a blockade of the left posterior area. The QRS complex remains unchanged. To clarify the diagnosis, readings are taken over a period of 24 hours or more.

Video: lesson on bundle branch blocks

Why is heart block dangerous?

The most dangerous is considered complete atrioventricular block., since it has serious consequences, manifested in the following:

1. The occurrence of chronic heart failure, accompanied by fainting and collapse. Over time, it will progress, causing exacerbations of cardiovascular diseases (in particular), chronic kidney diseases, etc.
2. Against the background of a slow rhythm, they develop, including ventricular tachycardia.
3. A frequent complication is that leads to hypoxia (oxygen starvation) of the brain and attacks of MAS, the frequent occurrence of which in older people is the cause.
4. Sometimes an attack of MAS causes sudden death. Therefore, it is important to provide emergency assistance in a timely manner: perform, if necessary, or perform forced ventilation.
5. During heart attacks or post-infarction conditions, complete heart block can cause.

Diagnosis

When some of the ventricular contractions are lost, their number decreases. This happens both with complete and partial blockade, including functional blockade. To identify the nature of its occurrence, a so-called atropine test is used. The patient is given atropine. An incomplete blockade, the occurrence of which is not associated with pathological changes, then disappears literally after half an hour.

On the electrocardiogram, only the waves are modified, showing that the impulse exciting the contraction passes from the atrium to the ventricle very slowly. With partial second-degree heart block, the cardiogram shows that the impulse passes with a slowdown. The wave of atrial contraction is recorded, but there is no wave indicating ventricular contraction. Partial blockade of the right leg is recorded on the cardiogram by slight changes in the thoracic leads on the right side and the appearance of small notches on the S wave.

Pathology treatment method

Treatment for heart block (antrioventricular) is prescribed depending on the type and cause of its occurrence. For first-degree atrioventricular block, constant clinical monitoring of the patient is sufficient. Drug therapy is carried out if his condition worsens. If the blockade develops against the background of a heart disease (or acute), then the underlying disease is eliminated first. The treatment method for 2nd and 3rd degree blockade is selected taking into account the location of the conduction disorder.

• If the blockade is of the paroxysmal type, then treatment is carried out with sympathomimetic agents (isadrin) or subcutaneous administration of atropine.
• With a distal blockade, drug therapy does not give the desired effect. The only treatment is electrical stimulation of the heart. If the blockade is acute and occurs as a result of myocardial infarction, then temporary electrical stimulation is performed. In case of persistent blockade, electrical stimulation should be carried out continuously.
• In case of sudden complete blockade, if it is not possible to perform electrical stimulation, a tablet is placed under the patient’s tongue Isuprel or Euspirana(or half a tablet). For intravenous administration, these drugs are diluted in glucose solution (5%).
• Complete heart block that develops against the background of digitalis intoxication is eliminated by withdrawing glycosides. If the blockade, the rhythm of which does not exceed 40 beats per minute, persists even after discontinuation of glycosides, intravenous Atropine. In addition, intramuscular injections are given Unitola(up to four times a day). If necessary (for medical reasons), temporary electrical stimulation is performed.

Under the influence of drugs on the vagus nerve, there are often cases when complete heart block turns into partial.

help yourself

In case of incomplete blockade, specific drug treatment is not required. But care must be taken to reduce the likelihood of its progression to more severe forms. And the symptoms that arise, such as dizziness and heaviness in the chest, also cannot be ignored. Therefore, it is recommended to reconsider your lifestyle and diet, and give up bad habits. If you experience discomfort caused by the blockade, do the following:

Complete heart blocks

Let's look at what a complete intraventricular block caused by pathological changes looks like on an ECG. The amount of damage to each branch of the left leg of His is indicated by the deviation of the isoline towards negative or positive values. It is located neutrally (zero position), when excitation is transmitted to the ventricles in a normal rhythm. When the passage of a pulse is disrupted, broadening is recorded QRS complex, which in some cases reaches more than 0.18 s.

With a significant increase in depolarization caused by conduction disturbances in the His bundle, early. On the electrocardiogram this process is recorded as follows:

• Segment ST in the left parts of the chest is shifted below the isoline; prong T takes the form of a negative equilateral triangle.
• Segment ST in the right parts of the chest - above the isoline, tooth T with a positive value.

When the right ventricular block occurs, the following occurs:

1. A low tooth is formed S greater width;
2. Prong R, on the contrary, narrow, but tall;
3. QRS the complex is shaped like the letter M.
4. Secondary repolarization (early) is displayed in the chest leads on the right with a convex upward segment ST, which has a slight downward shift. In this case, the tooth T- with inversion (upside down).

Complete atrioventricular block, which occurs as a result of pathological changes in the myocardium or against the background of an overdose of certain types of drugs, can develop in a distal or proximal type.

• The proximal type of block occurs when the ventricular pacemaker is located in the atrioventricular node. On the ECG this type of blockade is marked by a normal (not widened) complex QRS, the frequency of ventricular contractions is quite high (up to 50 per minute).
• In the distal type, the ventricular pacemaker has a lower idioventricular location. It is the bundle of His with all its branches. It is called a third-order automatic center. The electrocardiogram shows that the number of ventricular contractions is reduced, it does not exceed 30 per minute. This is indicated by the broadening of the complex QRS more than 0.12 s and overlap with the ventricular QRS tooth complex R. It may have a changed shape (if the automatic impulse occurs below the point at which the His bundle begins to branch). The ventricular complex retains an unchanged shape if the initial point of localization of the automatic impulse is located in the bundle itself.

With atrioventricular block, simultaneous contraction of the ventricles and atria occurs. This gives an increased sound of the first tone, which is called “cannon”. It is clearly audible when listening. The symptoms of this type of blockade depend on the degree of circulatory disturbance and the causes that cause it. If the frequency of ventricular contractions is high enough (at least 36 per minute), and there are no concomitant diseases, then patients do not experience discomfort or unpleasant sensations. In some cases, when cerebral blood flow decreases, dizziness occurs, and consciousness begins to periodically become confused.

With an increase in the duration of the interval between ventricular contractions, partial AV block can become complete, causing acute circulatory disorders in the brain. It is often accompanied by a slight eclipse of consciousness and heart pain. In more severe cases, MAS attacks occur, accompanied by convulsions, and the person loses consciousness for a short time. Prolonged ventricular arrest can cause instant death due to ventricular fibrillation.

Drug therapy for complete blockade

Therapy for complete blockade of any type is carried out based on etiology and pathogenesis.

Radical methods include implantation. Indications for its use are:

• low ventricular rate;
• increased period of asystole (more than 3 s);
• occurrence of MAS attacks;
• complete blockade, complicated by persistent heart failure, angina pectoris and other diseases of the cardiovascular system.

Forecast

A favorable prognosis is given only with partial blockades. The development of a complete third-degree block leads to complete disability, especially if it is complicated by heart failure or occurs against the background of myocardial infarction. The implantation of a pacemaker will make it possible to make more favorable prognoses. When used, some patients may experience partial restoration of their ability to work.

Features of heart block localizations

His bundle and its blockade

His bundle block has distinctive features. It may be constant or appear periodically. Sometimes its occurrence is associated with a certain heart rate. But the most important thing is that this type of heart block is not aggravated by severe disease. And although this blockade in itself does not pose a threat to human health, it can serve as a harbinger of more serious heart disease (in particular myocardial infarction). Therefore, it is necessary to periodically undergo a heart examination using an ECG.

A pathological conduction disorder, the location of which becomes the bundle branch, can pose a threat to life. This is explained by the fact that she is a fourth-order pacemaker. It regenerates low-frequency pulses (no more than 30 per minute). It should be noted that the highest frequency impulse (up to 80 per minute) is formed in the sinoatrial node. The second-order atrioventricular node that follows it produces impulses with a decrease in frequency to 50 per minute. The His bundle (third-order pacemaker) generates impulses at a frequency of 40 per minute. Therefore, in the event of obstruction of the excitatory impulse along the pacemakers of all levels, they are automatically formed in the Purkinje fibers. But their frequency decreases to 20 per minute. And this leads to a significant decrease in the blood supply to the brain, causes its hypoxia and leads to pathological irreversible disorders in its work.

Sinoatrial heart block

violation of the generation or conduction of impulses at the level of the sinus node

A distinctive feature of sinoatrial block (SB) is that it can occur simultaneously with other types of heart rhythm disturbances and conduction pathologies. Sinoatrial block is sometimes caused by a weak sinus node. It can be permanent, transient or have a latent form.

In this case, three stages of its manifestation are distinguished.

• At the first stage, the passage of the impulse through the sinoatrial region is delayed. It can only be detected by electrophysiological studies.
• At the second stage, two types of SB should be considered. With the development of the first type, a periodic blocking of one impulse occurs at the exit from the atria. Sometimes several impulses in a row are blocked at once, with Weckenbach periodicity. The R-R interval corresponding to the pause is extended. But its value is less than twice the R-R interval that precedes the pause. Gradually, the intervals that follow a long pause become shorter. It is detected during a standard ECG, on which the pulse frequency is displayed without change.
• The second type is characterized by a sudden disruption of impulse conduction, in which there are no Weckenbach periods. On the cardiogram, the pause is recorded as doubling, tripling, etc. pauses R-R.
• The third stage is a complete disruption of impulse conduction in the atria.

Interatrial block

One of the small rare heart rhythm disorders is interatrial block. Like all other types, it has three stages.

1. The impulse of excitation is delayed.
2. Periodic blocking of the excitatory impulse entering the left atrium.
3. Dissociation of atrial activity or complete conduction disturbance.

The third stage is characterized by the automaticity of the formation of impulses from two sources at once: the sinoatrial and gastroatrial node. This is due to the fact that due to the emerging pathology of the sinus node, the number of impulses formed in it sharply decreases. At the same time, an accelerated formation of the number of impulses in the AV node occurs. This leads to simultaneous contraction of the ventricles and atria, regardless of each other. This type of blockade has another name - “Pre-ventricular dissociation” or dissociation with interference. On the electrocardiogram it is recorded together with normal contractions. When listening, a more sonorous “gun” tone is heard from time to time.

Heart block in childhood

In childhood and adolescence, the same types of blockade are formed as in adults, differing only in the cause of occurrence: acquired (due to a disease) or congenital etiology. Acquired forms in children and adolescents are secondary, and develop as a complication after surgery to eliminate various cardiac pathologies, or against the background of diseases with an inflammatory or infectious etiology.

Congenital blockade can be caused by the following reasons:

• Diffuse damage to the mother's connective tissue.
• The presence of type II diabetes mellitus (insulin-dependent) in the mother. This syndrome is called Legerne disease.
• Not fully formed right leg of the His bundle.
• Anomaly in the development of the interatrial and interventricular septa.
• M.Lev disease

The most dangerous is the third degree of atrioventricular or complete transverse block caused by damage to all three legs of the His bundle. When they occur, the conduction of impulses to the ventricles from the atria is completely absent. It does not always have pronounced symptoms. Its only manifestation is bradycardia.

But as it progresses, there is a gradual stretching of the heart chambers, hemodynamic disturbances with a slowdown in overall blood flow. This leads to a deterioration in the supply of oxygen to the brain and myocardium. As a result of hypoxia, children experience neuropsychic disorders. They remember and assimilate educational material poorly, and lag behind their peers in physical development. The child often experiences dizziness, weakness, and slight fainting. Any stressful situation and increased physical activity can lead to fainting.

In the treatment of complete blockade in children, anti-inflammatory and hormonal drugs, antioxidants, nootropics and vitamin complexes are used. Severe forms, in which drug therapy is ineffective, are recommended to be eliminated by cardiac pacing. Pacemakers are also used in the treatment of congenital forms of heart block accompanied by bradycardia. Emergency assistance for loss of consciousness (attack of MAS) consists of closed (indirect) cardiac massage, administration of atropine or adrenaline. Continuous monitoring of conductivity through an ECG is recommended.

Congenital heart blocks often cause the death of a child in the first year of life. In a newborn they are manifested by the following symptoms:

1. Blueness or cyanosis of the skin, lips;
2. Increased anxiety or, conversely, excessive lethargy;
3. The baby refuses to take the breast;
4. He has increased sweating and...

For mild forms, drug treatment is not required. But the child needs constant monitoring by a cardiologist. In some cases, surgical intervention is recommended, which can save the baby’s life.

Modern cardiology knows many pathologies of the cardiovascular system. Most of the ailments are independent in nature, and some of them manifest themselves as an unpleasant addition to the main heart defect.

Perhaps one of the last is atrioventricular blockade, which manifests itself in the form of a disturbance in the conduction of impulses between the ventricles and atria. Today we will talk in more detail about the mechanism of development of this disease, the principles of its diagnosis and treatment. Interesting? Then be sure to read the material below to the end.

Atrioventricular block is a pathology of the heart in which the impulse interaction between the atria and ventricles of the organ is impaired. To be more precise, the electrophysiological conductivity begins to differ, as a result of which the contraction of specific parts of the heart muscle occurs incorrectly.

Any heart disease in a person can be a potential cause of atrioventricular block. According to official statistics, most pathologies of this kind are diagnosed in patients with ischemic disease, and.

Less commonly, the cause of the disorder is complications caused by surgical intervention in the structure of the cardiac apparatus or.

By the way, official statistics also confirm that with age the risk of atrioventricular blockade is noticeably higher. In any case, these are only statistical data; specific scientifically confirmed information regarding the occurrence of this disease is still not available.

Symptoms of atrioventricular block are also unremarkable. Often, this disease occurs together with other pathologies of the cardiovascular system, so their course is accompanied by the appearance of typical symptoms for a cardiac patient:

• dyspnea
• abnormal heart rhythm
• chest pain
• dizziness

It is impossible to accurately diagnose atrioventricular block based solely on the symptoms shown. At a minimum, you will need to undergo a basic list of examinations from a cardiologist.

Degrees of the disease

The main classification of atrioventricular block is carried out through the degrees of this disease:

• 1st degree atrioventricular block is a disease associated with incomplete asynchrony of the impulse interaction between the atria and ventricles. Otherwise, such a course of the disease is called “incomplete blockade.” In the results, degree 1 of pathology is manifested by a prolongation of the heartbeat interval with the designation “P-Q” (extension of more than 0.2 seconds, persistent).
• 2nd degree atrioventricular block is a pathology that also occurs in the form of incomplete blockade, but is characterized not by a stable disturbance of impulse interaction, but by a periodic loss of ventricular asynchrony. On the ECG, the disease manifests itself in the form of indicators similar to grade 1, but with a pronounced periodicity.
• 3rd degree atrioventricular block is a heart defect, which is expressed in complete or almost complete asynchrony of the atria and ventricles. This condition of the heart apparatus is also called complete blockade. On the results of ECG 3, the degree of the disease is reflected by indicators completely opposite to the norm.

Depending on the type of disorder detected in the patient, the further course of therapy is determined. By the way, this moment plays a crucial role in the treatment of atrioventricular blockades, since different types of lesions affect completely different parts of the heart, which requires different treatment approaches.

The danger of blockade

As we found out above, atrioventricular block is a violation of the impulse interaction of the parts of the heart associated with its slowdown. The functioning of an organ in this mode is naturally not a good thing.

This is due to the fact that this state of affairs causes serious disturbances in heart rhythm. The latter, in turn, provoke arrhythmic disorders of the cardiac apparatus and accompanying ailments.

Often, long-term, severely ongoing or untreated blockade provokes the development of the following heart pathologies:

1. previously noted arrhythmias
2. thromboembolism
3. heart attack and other myocardial diseases
4. ischemic stroke

Fortunately for many cardiologist patients, the noted complications with atrioventricular block are not rapidly developing illnesses, but the result of a long course of disorders and the lack of their treatment. That is, it is very simple to prevent these problems from occurring - just organize competent treatment and follow the basic advice of specialists on maintaining a healthy lifestyle.

Diagnostics

It was previously noted that atrioventricular blockade cannot be diagnosed even indirectly based on symptoms.

To guarantee the detection of the disease, it will be necessary to conduct several specialized cardiological examinations at once. The list of the latter includes:

• An ordinary ECG is the main and most informative method in diagnosing many heart blocks, including atrioventricular block. Only in a colossally small number of cases does this type of examination fail to identify the disease in question. Signs of atrioventricular block on the ECG results can be traced in the “P-QRS” intervals in the so-called dropped complexes, which signal the incorrect passage of certain impulses.
• Daily ECG monitoring is a diagnostic method used in rare cases when other examination methods do not give an unambiguous result. The essence of its implementation is completely similar to an ordinary ECG, with the only exception that daily monitoring is carried out over a long period of time, and a standard examination - only a few minutes.
• ECG with stress - this research method is used not for the purpose of identifying a blockade, but to check the tolerance of an already detected disease to physical activity on the part of the patient. This approach often allows one to determine the risks of complications.
• , x-rays, and - types of examinations used to possibly identify the root cause of the blockage. That is, diagnostic data are needed only to determine the heart pathology that caused the disruption of impulse interaction, and not the blockade itself.

Based on the results of the examinations, the cardiologist will be able to give the patient an accurate diagnosis, after which it is already possible to determine the further direction of therapy, its urgency and the nuances of treatment. Let us note that decoding the results of an ECG and other heart diagnostics is not an easy and extremely responsible matter, so it should not be carried out without the participation of a doctor.

Treatment and prognosis

The treatment process for atrioventricular blockades differs markedly in different patients, which is caused, first of all, by the specificity of the pathology.

Often, grade 1 illnesses that do not manifest themselves clinically do not require therapy, and cardiologists advise patients only to try to lead a correct lifestyle and undergo systematic examinations. However, more severe types of the disease must be treated.

Often their therapy consists of organizing the following stages:

1. Drug optimization of heart function.
2. Normalization of nutrition and lifestyle.
3. Medical or surgical elimination of the root cause of the disorder.
4. Maintaining the patient's health.

In cases where the atrioventricular blockade cannot be eliminated in the manner described above, they resort to its relief. What does it mean? This means that with the help of a special pacemaker, the patient’s heart function is normalized for the rest of his life. Forced cardiac pacing can be either temporary or permanent. It all depends on the characteristics of a particular case.

In the process of treating atrioventricular blockades, nutritional adjustments are very important.

Most cardiologists agree that patients with this diagnosis require:

• First, give up any junk food (fast food, a lot of sweets, fatty foods, highly salty foods).
• Secondly, increase the consumption of proteins, vegetable fats and complex carbohydrates (boiled meat, cereals, nuts, etc.).
• Thirdly, eat small meals and at normal intervals.

More information about ECG can be found in the video:

Also, patients with atrioventricular block are prohibited from physical activity (either completely or partially). It’s probably not worth talking about the need for normal sleep, lack of stress and similar things. And, of course, it is important not to forget about systematic studies by a cardiologist.

Perhaps that’s all for today’s topic. We hope that the material presented was useful to you and provided answers to your questions. Good health to you!

Dilatation of the four chambers of the heart can be diagnosed based on a combination of electrocardiographic signs typical of isolated enlargement of each of the four cavities of the heart, which is rarely observed. However, the diagnosis is possible in certain situations when there is enlargement of the two ventricles and atrial fibrillation (enlargement of the left atrium).

In the broadest sense of the word blockade they say if the conduction of an electrical impulse is delayed in a certain part of the conduction system of the heart.

Delay can occur in any area, from the SA junction to the ventricular myocardium, and may cause slower activation in the corresponding area. Ventricular block has three degrees. With a first-degree blockade, impulse conduction is delayed, with a second-degree blockade, impulses are partially conducted, and with a third-degree blockade, impulses are not conducted at all.

The term "blockade" used in an electrophysiological rather than an anatomical sense. Due to this, the blockade can be antegrade or retrograde, for example, antegrade atrioventricular block can be accompanied by ventricular atrial conduction of ventricular extrasystoles, and transient blockade can also occur even with an unchanged ventricular conduction system, for example, after the administration of certain medications or as a result of electrolyte disturbances.

Ventricular heart blocks

Traditionally considered. that the electrical impulse can be blocked at the level of the trunk of the right or left bundle branch, creating a right or left bundle branch block, respectively.

However, in the present It has been known for some time that conditions such as right or left bundle branch block can be caused not only by damage to the trunk, but also by damage occurring in the proximal part of the His bundle. Moreover, in recent years, blockades of the superior anterior branch and blockades of the inferoposterior branch of the left bundle branch have begun to be distinguished. The validity of the diagnosis of right zonal blockade is also discussed.

Therefore, specialists Faculty of Medicine at the University of Barcelona believe that the terms “right ventricular block” and “left ventricular block” are more accurate than right bundle branch block and left bundle branch block. In this case, the classic picture of right and left bundle branch block will correspond to complete block of the right and left ventricle, regardless of where it occurs. The slow conduction zone can be located in various areas of the His-Purkinje system. The following is the classification of right ventricular block (delayed activation of the right ventricle):

A. Complete

Blockade may occur proximally (in the trunk or, less commonly, in the bundle branches) or peripherally (in the moderator bundle or, less commonly, in the Purkinje fiber network). The ECG picture depends on the severity, and not on the area where the blockade occurs.

1. III degree. The configuration corresponds to the type III of the Mexican school.

2. I degree. The configuration corresponds to Type I and II of the Mexican school.

3. II degree. Corresponds to a specific type of ventricular aberration. The blockade area is in the proximal part of the trunk.

B. Zonal

In the absence of obvious r waves‘ in lead V1 (anterosuperior and posteroinferior hemiblock) and the QRS complex<0,12 с.

A. Complete

The location of the block can be proximal (trunk or, less commonly, bundle branch) or peripheral (Purkinje fiber network or combined left bundle branch block). Some types of peripheral blockade may give a different ECG picture (see text).

I degree (incomplete). Corresponds to type I and II, according to the classification of the Mexican school.

The term " ventricular block" means that the activation of the corresponding ventricle is delayed, which explains the observed changes in the electrocardiogram.

We know how difficult it is change the usual definitions in medicine and most likely the terms “right leg block” and “left leg block” will remain prevalent. However, at the very least they should be considered as the result of disorders in the bundle branches.

Causes of atrioventricular blockade, mechanism of development

Etiology and pathogenesis

One of the common causes of atrioventricular conduction disturbances is coronary heart disease. According to M.Ya. Rudy and A.P. Zysko, V.L. Doshchitsyn, atrioventricular block of various degrees is detected in 10-15% of patients with myocardial infarction. The reason for the slowing of atrioventricular conduction can also be rheumatic carditis, myocarditis of various etiologies, myocardial, atherosclerotic and post-infarction cardiosclerosis, hyperkalemia.

There are reports of the development of atrioventricular block in 10% of cases after heart surgery.

Sometimes atrioventricular blockade of various degrees occurs due to intoxication with cardiac glycosides, taking various antiarrhythmic drugs (quinidine, beta-blockers, novocainamide, etc.).

Cases of congenital complete atrioventricular heart block, sometimes in combination with congenital heart defects, have been described.

Sometimes atrioventricular block (usually incomplete) is a consequence of increased vagus nerve tone. Vagal stimulation (pressure on the carotid sinus, eyeballs) can lead to transient disturbances of atrioventricular conduction. The role of the vagus nerve in the development of atrioventricular block is also confirmed by experimental studies by E.B. Babsky and L.S. Ulyaninsky. This factor appears to be of great importance in the occurrence of atrioventricular block in practically healthy people and in athletes.

The mechanism of development of atrioventricular block is not completely clear.

To explain the pathogenesis of atrioventricular blockade, various theories have been put forward: decremental conduction, “hidden” conduction, multiple conduction pathways, and others.

I.A. Chernogorov and I.I. Isakov associate disturbances in atrioventricular conduction with a decrease in the functional lability of the myocardium. At the same time, waves of excitation arriving at the site of reduced lability deepen its parabiotic state.

There are three degrees of atrioventricular block.

Atrioventricular block of the first degree is an incomplete blockade, characterized by a persistent prolongation of the P-Q interval on the ECG by more than 0.2 s. In the case of a sharp prolongation of the P-Q interval or when blockade is combined with tachycardia, the P wave merges with the T wave of the preceding complex, which is sometimes incorrectly mistaken for the rhythm of the atrioventricular junction.

Second degree atrioventricular block is an incomplete block characterized by periodic loss of ventricular complexes.

There are two types of blockades:

1. Samoilov-Wenckenbach type, or Mobitz-I type, is characterized by a gradual lengthening of the P-Q interval on the ECG and subsequent more or less regular loss of the ventricular complex;
2. Mobitz-I type, characterized by a normal or constantly prolonged P-Q interval and periodic loss of the ventricular complex.

Atrioventricular block of the second degree, type Mobitz-I, is observed with damage to the proximal parts of the His bundle, type Mobitz-II - with damage to the distal parts of the conduction system of the heart at the level of the branches of the His bundle. Therefore, on the ECG, the complexes are usually widened and deformed.

Atrioventricular block of the third degree is a complete atrioventricular block, in which not a single sinus impulse is conducted to the ventricles; there are two autonomous rhythms - sinus, or atrial, and ventricular; atrial and ventricular complexes follow independently of each other in the correct rhythm.

Complete atrioventricular block can develop at three levels: with damage to the atrioventricular node (nodular block, proximal block), with damage to the trunk of the His bundle (trunk block) and with damage to all three branches of the His bundle (three-bundle, or trifascicular, block , blockade of distal type).

Complete atrioventricular block can be persistent, or permanent, transient and intermittent (intermittent).

Prof. A.I. Gritsyuk

“Causes of atrioventricular blockade, mechanism of development” section Emergency conditions

Additional Information:

Emergency medicine

Atrioventricular block— when this type of conduction is disrupted, the impulse is blocked at the border of the atria and ventricles. Previously, it was believed that the conduction of impulses through the atrioventricular node was disrupted. However, as has been established in recent years, the delay in impulse conduction, both normally and during blockades, occurs in two places:

• 1) at the junction of the atria with the atrioventricular node (less significant);
• 2) at the junction of the atrioventricular node and the His bundle (more significant).

Thus, when speaking about atrioventricular blockades, one should keep in mind the slowdown in the conduction of impulses or their blockade in the atrioventricular junction.

Etiology and pathogenesis. One of the common causes of atrioventricular conduction disturbances is coronary heart disease. According to M. Ya. Ruda and A. P. Zysko (1977), V. L. Doshchitsyn (1979), atrioventricular block of various degrees is detected in 10-15% of patients with myocardial infarction. The reason for the slowing of atrioventricular conduction can also be rheumatic carditis, myocarditis of various etiologies, myocardial, atherosclerotic and post-infarction cardiosclerosis, hyperkalemia.

There are reports of the development of atrioventricular block in 10% of cases after cardiac surgery (C. XV. et al. 1963).

Sometimes atrioventricular blockade of various degrees occurs due to intoxication with cardiac glycosides, taking various antiarrhythmic drugs (quinidine, beta-blockers, novo-cainamide, etc.).

Cases of congenital complete atrioventricular heart block, sometimes in combination with congenital heart defects, have been described (B. Landtman, 1964).

In very rare cases, heart tumors are the cause of atrioventricular block.

Sometimes atrioventricular block (usually incomplete) is a consequence of increased vagus nerve tone. Vagal stimulation (pressure on the carotid sinus, eyeballs) can lead to transient disturbances of atrioventricular conduction. The role of the vagus nerve in the development of atrioventricular block is also confirmed by experimental studies by E. B. Babsky and L. S. Ulyaninsky (1960). This factor appears to be of great importance in the occurrence of atrioventricular block in practically healthy people and in athletes.

The mechanism of atrioventricular blockade has not been fully elucidated.

To explain the pathogenesis of atrioventricular blockade, various theories have been put forward - decremental conduction, “hidden” conduction, multiple conduction pathways, and others.

I. A. Chernogorov (1948, 1962) and I. I. Isakov (1953) associate disturbances in atrioventricular conduction with a decrease in the functional lability of the myocardium. At the same time, waves of excitation arriving at the site of reduced lability deepen its parabiotic state.

Distinguish three degrees of atrioventricular block.

First degree atrioventricular block - this is an incomplete blockade, characterized by a persistent prolongation of the P-Q interval on the ECG over 0.2 s. In the case of a sharp prolongation of the P-Q interval or when blockade is combined with tachycardia, the P wave merges with the T wave of the preceding complex, which is sometimes incorrectly mistaken for the rhythm of the atrioventricular junction.

Second degree atrioventricular block - This is an incomplete blockade, characterized by periodic loss of ventricular complexes. There are two types of blockades:

1) Samoilov-Wenckenbach type, or Mobitz-I type, is characterized by a gradual lengthening of the P-Q interval on the ECG and subsequent more or less regular loss of the ventricular complex;

2) Mobitz type II, characterized by a normal or constantly prolonged P-Q interval and periodic loss of the ventricular complex.

Atrioventricular block of the second degree, type Mobitz-I, is observed with damage to the proximal parts of the His bundle, type Mobitz-P - with damage to the distal parts of the conduction system of the heart at the level of the branches of the His bundle. Therefore, on the ECG, the complexes are usually widened and deformed.

Atrioventricular block of the third degree is a complete atrioventricular block, in which not a single sinus impulse is conducted to the ventricles; there are two autonomous rhythms - sinus, or atrial, and ventricular; atrial and ventricular complexes follow independently of each other in the correct rhythm.

Complete atrioventricular block can develop at three levels: with damage to the atrioventricular node (nodal block, proximal block), with damage to the trunk of the His bundle (trunk block) and with damage to all three branches of the His bundle (three-bundle or trifascicular block, distal block) .

With nodal block, the pacemaker is located high, in the atrioventricular junction, and therefore bradycardia is least pronounced; with brainstem blockade, bradycardia is more pronounced, since the source of the rhythm is lower; finally, with a three-fascicle blockade, the ventricular rhythm is the lowest located, with the most pronounced bradycardia.

Complete atrioventricular block can be persistent, or permanent, transient and intermittent (intermittent). The clinical picture of atrioventricular block is determined by the underlying disease and the degree of blockade. Subjective symptoms are usually absent as long as there are no heart rhythm disturbances. With atrioventricular block of the second degree, patients complain of interruptions in the activity of the heart, sometimes slight dizziness.

With atrioventricular blockade of the third degree (complete) . when ventricular contractions decrease to less than 40 per minute, dizziness, darkening of the eyes, and short-term attacks of loss of consciousness are observed. Against the background of a sharp decrease in rhythm, Morgagni-Adams-Stokes syndrome may develop. Sometimes, as a result of chronic cerebral hypoxia, mental disorders are observed in the form of a peculiar combination of inappropriately elevated mood with motor retardation.

During cardiac percussion, the size of the boundaries of cardiac dullness is determined depending on the underlying disease.

When auscultating the heart in patients with first-degree atrioventricular block, a presystolic three-part rhythm is sometimes heard (an additional dull tone of atrial contraction) due to a significant prolongation of the P-Q interval. On auscultation, during a second degree block, the correct rhythm is interrupted by long pauses (loss of ventricular contractions). With complete (III degree) atrioventricular block, a rare regular heart rhythm and changing sonority of the 1st tone are heard. Usually the 1st tone above the top is dull, but from time to time its sonority intensifies, and then the so-called Strazhesko cannon tone appears. N.D. Strazhesko (1908) explained this phenomenon by the simultaneous contraction of the atria and ventricles. However, V.F. Zelenin (1956) and L.I. Fogelson (1958), based on electrophonocardiographic studies, showed that the “cannon tone” occurs when atrial contraction somewhat precedes ventricular contraction and the closure phases of the atrioventricular valves approach each other. Sometimes atrial sounds together with ventricular ones form a transient three-part rhythm.

It is almost impossible to distinguish clinically between atrioventricular blockade (nodal (proximal or high), brainstem and trifascicular (distal or low). Based on the heart rate, one can only guess where the source of the rhythm is: with moderately expressed bradycardia - high, i.e. proximally, with pronounced bradycardia - low, i.e. distally.

Incomplete atrioventricular block can become complete, and vice versa. This alternation of varying degrees of blockade can result in persistent complete atrioventricular block.

The addition of other arrhythmias plays a major role in the clinical course of atrioventricular block. Most often, atrioventricular block is combined with ventricular extrasystole, less often with atrial fibrillation or flutter (Frederick's syndrome).

Complete atrioventricular block, joining the underlying disease, can cause decompensation or intensify it.

Prognosis for atrioventricular block I degree favorable. With II and III degree blockade, the prognosis depends on the underlying disease, the frequency of ventricular contraction and the condition of the myocardium. With complete atrioventricular block, the prognosis is always unfavorable. However, nowadays, when implantation of an artificial pacemaker is increasingly being carried out, it is becoming more and more favorable.

Prevention of atrioventricular blockades- this is, first of all, active, adequate and comprehensive treatment of the underlying disease. It is almost impossible to predict the occurrence of a blockade. However, it should be borne in mind that atrioventricular blockade of the first degree can develop into a blockade of the second degree, and a blockade of the second degree into a blockade of the third degree. To prevent life-threatening complete (III degree) atrioventricular blockade, it is important to eliminate the II degree blockade of the Mobitz-I type, and even more the II degree blockade of the Mobitz-II type. Since this is often impossible to achieve with medication, such patients need to have an electrode inserted for prophylactic purposes and, if complete blockade occurs, temporary cardiac stimulation should be started immediately.

Emergency conditions in the clinic of internal diseases. Gritsyuk A.I. 1985

Disease class:

Other heart diseases

Description

Precardioventricular blockade. When this type of conduction is disrupted, the impulse is blocked at the border of the atria and ventricles. Previously, it was believed that the conduction of impulses through the atrioventricular node was disrupted. However, as shown in recent years, impulse conduction, both normally and during blockades, is delayed in two places: 1) at the junction of the atria with the atrioventricular node (less significant) 2) at the junction of the atrioventricular node and the His bundle (more significant ). Thus, when speaking about atrioventricular blockades, one should keep in mind the slowdown in the conduction of impulses or their blockade in the atrioventricular junction. III degree - complete atrioventricular block, in which not a single sinus impulse is conducted to the ventricles; there are two autonomous rhythms - sinus, or atrial, and ventricular; atrial and ventricular complexes follow independently of each other in the correct rhythm. Complete atrioventricular block can develop at three levels: with damage to the atrioventricular node or connection (nodal block, proximal type block), damage to the trunk of the His bundle (trunk block) and damage to all three branches of the His bundle (trifascicular block). Complete atrioventricular block can also be persistent or permanent, transient and intermittent (intermittent). Symptoms The clinic is determined by the nature of the underlying disease and the degree of blockade. Subjective symptoms are usually absent as long as there are no heart rhythm disturbances. With atrioventricular block of the third degree (complete), in the case of a decrease in ventricular contractions of less than 40 per minute, dizziness, darkening of the eyes, and short-term attacks of loss of consciousness are possible. Against the background of a sharp decrease in rhythm, Morgagni-Edams-Stokes syndrome may develop. Sometimes, as a result of chronic cerebral hypoxia, mental disorders are observed in the form of a peculiar combination of inappropriately elevated mood with motor retardation. With complete (III degree) atrioventricular block, a rare regular heart rhythm and changing sonority of the 1st tone are heard. Usually the 1st tone above the top is dull, but from time to time its sonority intensifies, and then the so-called Strazhesko cannon tone appears. Complete atrioventricular block, joining the underlying disease, can cause decompensation or intensify it. Diagnostics The main method for detecting atrioventricular block and bundle branch block is standard electrocardiography and its varieties - transesophageal electrocardiography (TEECG), rhythmocardiography, daily ECG monitoring. To identify evidence of organic heart damage, echocardiography, MRI, MSCT, and cardiac PET are performed. Treatment Treatment of atrioventricular blockade should be aimed primarily at eliminating the etiological factor. Thus, in case of intoxication with drugs (cardiac glycosides, beta-blockers, etc.), their withdrawal is indicated. For rheumatism, infectious-allergic myocarditis or coronary heart disease - appropriate treatment of the underlying disease. Despite the therapy for atrioventricular block (especially complete), it is not always possible to avoid Morgagni-Edams-Stokes attacks. Therefore, in some cases they resort to temporary or permanent electrical stimulation of the heart, or pacing. Temporary cardiac stimulation is carried out for transient rhythm and conduction disturbances, permanent - for persistent forms. In case of AV blockades of cardiac origin (myocardial infarction, myocarditis, cardiosclerosis, etc.), a course of treatment with β-adrenergic stimulants (isoprenaline, orciprenaline) is carried out, and then implantation of an electrical pacemaker is indicated, restoring normal rhythm and heart rate. To decide on surgery, a consultation with a cardiac surgeon is necessary.