The term “violation of the intraventricular conduction of the heart” means that one to three bundles of the system malfunction. Cardiac blockades appear – barriers that interfere with the normal passage of nerve impulses of the main muscle of the body. For example, the processes of the heart slow down, the rhythm becomes less frequent, in special cases a complete stop may occur.
The main characteristic that tells us about the presence of a violation is the appearance of a heart block (complete or partial). In the first case, the nerve impulse is completely absent and the contractile work ceases. With partial blockade, slow activity is observed, the frequency of the pulse decreases.
In addition, such a disease, depending on the site of the lesion is divided into:
- blockade of the Guiss bundle legs;
- intraatrial block;
- AV blockade;
All possible causes of failure can be divided into two large groups: cardiac – caused by pathology of the heart and non-cardiac – provoked by other disorders.
- heart defects;
- myocardial infarction;
- cardiac ischemia;
- coronary arteriosclerosis;
- the consequences of surgical interventions (for example, due to valve prosthetics, radiofrequency catheter ablation).
- vascular dystonia;
- endocrine problems: hypothyroidism, diabetes mellitus;
- disorders of the respiratory system with tissue hypoxia – bronchospasm, chronic inflammation;
- irrational medication;
- arterial hypertension;
- alcohol poisoning;
- taking drugs;
Failure of the signal does not always indicate pathology. For example, a partial violation of conductivity along the right leg of the bundle of His is considered a variant of the norm, characteristic of individual young people.
Violation of the conductive function of the myocardium can be permanent and transient. Temporary “malfunctions” are detected against the background of physical activity (for example, in training and competitions). If after rest the situation normalizes, there is no cause for concern. But if the problem persists, and changes are visible on the ECG, you need to be examined by a specialist.
Permanent single-beam blockade of the right leg and individual branches of the left leg in people without cardiac pathology do not affect health and life expectancy.
The prognosis for the first occurrence of conduction disturbances resulting from organic damage to the heart depends on the severity of the underlying disease.
There are different opinions about the degree of influence of the left leg blockade on mortality rates. Some researchers do not consider single- and double-beam blockades as risk factors that reduce patient survival. According to other sources, a constant or recurring form of pathology can increase the likelihood of death from cardiac complications by 5 times.
The development of the left leg blockade in the acute period of myocardial infarction significantly worsens the prognosis: the mortality rate rises and is 40–50%.
The most unfavorable prognosis is trifascicular block due to the high risk of developing asystole.
- How common are intraventricular blockages?
- Diagnosis: signs on ECG and halter
- What is a violation of intraventricular conduction of the heart?
- Symptoms of the disease
- Myocardial conduction system
- Three-beam blockade
- How is ECG conductivity different?
- Clinical case
- How to determine the prognosis for impaired conductivity?
- 5 Conductivity disorder in children
How common are intraventricular blockages?
Impaired conduction within the ventricles can be detected in both children and adults. Among the pathologies detected by electrocardiography, the proportion of intraventricular blockade is up to 2,4%. An increase in the detection rate in elderly patients is noted.
By prevalence among the population:
- in the first place is a block in the left leg (anteroposterior branch);
- on the second – the right leg.
Impaired conduction in the posterior lower bundle is rare.
Diagnosis: signs on ECG and halter
The fact that the patient has a blockade, he can learn quite by accident. This applies to mono- and bifascicular blockades, since they do not affect the state of blood circulation. Patients with three-beam blockade may complain of dizziness, palpitations, fainting, shortness of breath, chest pain. Most often, patients present complaints of the underlying disease, which led to the development of conduction disorders.
Inspection, palpation and auscultation do not give a clear idea of the existing violations in the conduct, as there are no specific signs. A doctor may suspect something was wrong by the presence of split tones.
Electrocardiography (ECG) is the main method for detecting this kind of disturbance in the conduction system of the ventricles. The main sign of complete blockade of the right leg of the bundle of His is a change in the ventricular complex of QRS in the right thoracic leads – V1 and V2. The complexes exceed the normal duration and are modified, acquiring an M-shaped appearance.
Signs of blockade of the right bundle branch block
In addition to changes in the ventricular complex, a decrease in the ST segment with a negative T may be noted. With incomplete blockade, the existing changes in the appearance of the complexes and segments do not exceed their normal duration. In the case of blockade of the left leg, these changes are localized in the left thoracic leads – V5 and V6. The blockade of the anterior branch of the left leg is characterized by a sharp deviation of the electrical axis of the heart to the left, the posterior branch to the right.
Holter monitoring allows you to identify possible triggering factors of conduction disturbances by prolonged recording of an electrocardiogram throughout the day.
An intracardiac electrophysiological examination of the heart can be carried out when the question of the possible implantation of a pacemaker to a patient is considered.
The mechanism of conduction disturbance: in the case of a complete block of the right branch of the bundle, the right ventricle and the adjacent half of the ventricular septum get excited in another way. The wave of cell depolarization passes here from the left side of the interventricular septum, from the other ventricle. They are excited first, and the fibers slowly transmit impulses to the right ventricle.
Incomplete blockade is distinguished by the correct way of transmission, but the slowed down speed of the pulse.
The causes of the complete block are mainly diseases accompanied by overload of the right ventricle:
- chronic lung diseases with the formation of a “pulmonary heart”;
- congenital malformations, valve failure in children;
- of acquired defects, mitral stenosis is important, creating increased pressure in the pulmonary circulation;
- chronic ischemic disease, combined with arterial hypertension;
- myocardial infarction of the posterior diaphragmatic and apical region, the detection of pathology is regarded as an indicator of the high prevalence of the zone of necrosis and ischemia.
Radiologically overloaded right ventricle is seen by the expansion of the contours in the upper right
With a healthy heart, this type of blockade is rare.
The reasons for the incomplete blockade should be added:
- myocarditis (rheumatic heart disease, consequences of infectious viral diseases in a child);
- diffuse and focal cardiosclerosis;
- thickening of the left ventricle with hypertension;
- intoxication with drugs (digitalis derivatives, quin >
In these cases, delayed conduction indicates ventricular hypertrophy. Possible as a variant of the norm in athletes.
The mechanism of conduction disturbance: there are always obstacles to conducting excitation along the front and side walls of the left ventricle. First, the impulse passes through the left posterior branch, activates the interventricular septum and the bottom of the posterior wall. Then, through the Purkinje fibers, an excitation wave directed from the bottom up goes to the anterolateral part of the left ventricle.
- myocardial infarction of the anterior or lateral wall;
- focal cardiosclerosis;
- non-closure of the atrial septum;
- aortic malformations;
- insufficiency of mitral valve cusps;
- hypertrophic cardiomyopathy;
- myocardial dystrophy with metabolic changes.
The mechanism of conduction disturbance: impulse delivery is inhibited in the posterior lower part of the left ventricle. Excitation goes along the left anterior bundle to the myocardium of the anterolateral region, through the fibers of Purkinje spreads to the posterior and lower sections. The myocardium is activated along the front wall from top to bottom.
This type of block is rarely isolated, more common with blockade of the right bundle branch block.
Causes – focal changes in the left ventricle from the back wall with:
- posterior diaphragmatic myocardial infarction;
ECG for myocardial infarction
with left leg blockade
The mechanism of conduction disturbance: the block of the common trunk of the left leg should be located before branching into the front and rear branches or at the same time block the flow of pulses along both branches. The right ventricle is excited in the usual way, after it the wave is transmitted through the contractile cells to the left ventricle from right to left. In the case of an incomplete block, some of the pulses, although slowly, “break through” along the left leg.
The reasons for the occurrence of this type of conduction disturbance must be sought in a very extensive damage to the left ventricle with:
- acute transmural myocardial infarction;
- diffuse cardiosclerosis;
- aortic malformations and coarctation;
- malignant course of arterial hypertension.
The mechanism of conduction disturbance: the obstacle is located simultaneously in the right leg and the left front bundle (branch). The first through the intact left posterior branch excite the posterior wall and lower part of the left ventricle, along the anastomotic pathways – front and side. With a big delay, in a roundabout way, the impulses reach the right ventricle. This is the most common variant of intraventricular disturbances in the spread of arousal.
- chronic ischemic disease;
- acute widespread myocardial infarction with seizure of the interventricular septum;
- heart defects;
- diffuse sclerotic, inflammatory and degenerative lesions of the ventricles in Lenegra disease (degeneration, calcification and sclerosis of the conduction system inside the ventricles), Levy disease (fibrous growths in the interventricular septum).
The mechanism of conduction disturbance: through the left intact anterior branch, excitation enters the front and side walls of the left ventricle, then along the anastomoses it covers its posterior and lower sections. Lastly, impulses reach the right ventricle.
The causes do not differ from the widespread and deep lesions of the left ventricular wall described above. ECG signs combine changes in the chest leads during blockade of the right leg with a right-sided deviation of the electrical axis.
In most cases, doctors recommend taking vitamins, herbal remedies, and potassium preparations. Women who have heart disease or blockages are planning a cesarean delivery to prevent serious heart failure.
Any disturbances in the conduction of the heart can be in women in position. It is not a fact that all symptoms will appear, but it is not worth excluding such a possibility. And if you notice frequent dizziness, general weakness, shortness of breath and nervous instability, then these are obvious symptoms of the disease.
Before prescribing a medical course of treatment for a woman, an ECG study is needed to confirm the diagnosis.
Violation of intraventricular conduction during pregnancy is extremely rare, but this type of risk should not be excluded. If symptoms such as dizziness, frequent loss of consciousness, very frequent weakness, shortness of breath, nervousness are detected, you should immediately consult a doctor for help.
Before prescribing a course of treatment for a diagnosis of a violation of intraventricular conduction, it is first necessary to undergo an ECG. After confirming the diagnosis, you need to consider the harm that can be done to you and your child before prescribing drugs and carrying out procedures.
In order to accurately determine the violation of patency at the first stage, doctors use an electrocardiograph. If rhythmic inconsistencies are detected, Holter monitoring is performed – a specialized kind of ECG. The third stage will be the study of the locality of pathology with the help of the electro-Hiss beam.
Some medical tests that determine local violation of intraventricular conduction, suggest tests with physical exertion. Thanks to them, it is possible to establish an accurate picture of the course of the disease and find out what kind of heart block accompanies pathology. On how competently carried out the diagnosis will depend on the treatment.
Some medical tests that determine the location of the violation include tests with physical activity. This test establishes an accurate picture of the course of the disease and it turns out which blockade is associated with the pathology. A competent diagnosis is very important, since the further course of treatment will depend on this.
If you suspect a blockade, a person should contact a cardiologist. The following studies are shown to the patient:
- Echocardiography allows you to see the structure of the organ and assess the condition of the myocardium.
- Electrocardiography with exercise makes it possible to establish a relationship between rhythm disturbance and the intensity of physical activity.
- Daily monitoring of electrocardiography allows you to evaluate the rhythm of the body at different times of the day.
What is a violation of intraventricular conduction of the heart?
Of course, a person wonders about the cause of the violation of intraventricular conduction. What could it be? There are a number of prerequisites for the development of pathology:
- Changes in the cardiovascular system, not accompanied by organic deviations.
- Patient-borne diseases such as congenital malformations, ischemia, myocarditis, cardiomyopathy.
- The effect of the operation on the vessels of the heart.
- The negative impact of drugs, side effects.
Violation of intraventricular cardiac conduction – a pathology of one, two or three bundles of the intraventricular cavity, which lead to mono-, bi- or trifashicular block.
The concept of blockade implies violations of the normal impulse patency through the heart muscle system. But a violation does not mean the complete absence of a nerve impulse.
Intracardiac pathologies are accompanied by intraventricular blockade of various forms of abduction. And if there is no impulse, then this is a complete violation of the conductivity. When the interventricular impulse is slowed down, it is called incomplete local pathology (PNPH).
Violations are divided by the frequency of the lesion: intraventricular block of the left ventricle proximal and distal, bpn.
As is known, impulse conduction disturbance can be partial or complete. If in the first case, the blockade is most often asymptomatic, then the second is a significant threat to humans.
Heart contractions in children and adults are provided due to the work of the heart muscle – myocardium. Pulses in the heart are formed in the sinus-atrial (sinoatrial) node and then are sent to the bundles of Torel, Wenckebach, Bachmann, as well as to the atrioventricular node.
At the last indicated point, the impulse is slightly delayed so that the atria are normally reduced, and the blood enters the cavity of the left ventricle and the right ventricle. Then the path of the pulse lies in the trunk of the His bundle, from there – into the legs of the His bundle, to the myocardium of the ventricles and Purkinje bundles.
As a result, blood is discharged into the aorta and pulmonary artery.
According to the classification of V. L. Doshchitsin, all intraventricular conduction disorders are divided into:
- mono-, bi- and trifascicular depending on the defeat of one or two or three bundles;
- focal: local damage is not confirmed in all ECG leads;
- arborization: localized in the final part of Purkinje fibers;
- transient: changes alternate with proper conductivity;
- complete and incomplete;
- alternating: one or another type of blockade is revealed.
The pathological process can cause an impulse block at any level.
Depending on the place of interruption of the pulse, blockages are distinguished:
- monofascicular (single-beam): the block of the left front or back, only the right leg of His;
- bifascicular (two-beam): it is possible in two versions as one-sided (left leg) or two-sided (right with left front branch, right with left back branch).
- trifascicular (three-beam).
A variety of blockades is reflected in the decoding of the electrocardiogram. Conducting an impulse from the supraventricular nodes of the heart slows down or is completely interrupted. This violates the sequence of excitation of the ventricles, affects the biochemical processes in the myocardium, the usefulness of the cardiac output.
The causes of different types of blockades differ from each other, cause unequal changes. Consider how a violation of intraventricular conduction is formed in diseases of the myocardium.
The conduction system begins with the sinoatrial node, which is the source of the sinus rhythm. From it, impulses through specialized cells enter the atrioventricular node located in the zone of connection of the atria and ventricles. Further, the passage of pulses is carried out through a system of His fibers.
Signs of a partial blockade of impulses in the region of the right leg are sometimes found against the background of complete health and are considered congenital features.
But often the sudden problem of impulses is a consequence of heart disease. Possible causes of intraventricular conduction pathology:
- myocardial infarction
- attacks of ischemia
- atherosclerotic cardiosclerosis,
- heart failure,
- myocardial dystrophy,
- heart defects
- arterial hypertension,
- hypertrophy of the heart.
Conduction disorders are sometimes caused by electrolyte imbalance, drug intoxication, thyrotoxicosis, chronic obstructive pulmonary pathology, pulmonary thromboembolism.
Partial blockade of the right leg, accidentally detected by electrocardiography, is usually not a pathology and does not require treatment. But if a violation of intraventricular conduction of the heart occurred suddenly, it is necessary to find out the cause of the condition and prescribe adequate therapy. Treatment is carried out, influencing the causes of conduction disturbance: if conduction disturbance occurs due to myocarditis, aortic defect, pulmonary embolism – treatment of these pathologies is organized.
Often transient blockades develop due to myocardial ischemia. In this case, therapeutic measures are carried out aimed at improving the blood supply to the myocardium, the treatment of atherosclerosis. Treatment of the underlying pathology can lead to the elimination of the problem of impulses.
With myocardial infarction, intensive therapy is carried out to limit the area of necrosis, reduce the area of ischemia and combat complications of pathology, including life-threatening ones. The danger is a complete three-beam blockade, as a result of which asystole (cessation of heart contractions and electrical activity) can develop. Treatment is carried out using external and intracardiac pacing.
- Blockade of two legs of the bundle of His, manifested by a rare frequency of heart contractions, congestive heart failure, angina attacks.
- The combination of conduction pathology in the left or right leg of the bundle of His and atrioventricular block.
- The termination of the passage of pulses along the right leg and the posterior branch of the His system.
- Persistent conduction disturbance of both legs, persisting 3 weeks after a heart attack.
- The attacks of Morgagni-Adams-Stokes.
When exacerbation of the situation, for example, the occurrence of myocardial infarction, promptly injected probe. At first, treatment is reduced to eliminating the cause of the disease, and only then begins work to alleviate the symptoms.
The bundle of His provides the passage of an electrical impulse throughout the ventricular system of the heart. Therefore, a violation of its function and leads to the development of intraventricular blockade.
As a result, the impulse ceases to flow to the ventricular muscle fibers. Based on how much the conduction function of the bundle of His is lost, intraventricular blockades are divided into types:
- right legs (branches);
- left front leg;
- left hind leg.
If the transmission of an impulse in the ventricular system stops completely, a complete blockade develops, if the impulse passes through individual fibers or passes slowly and in violation, they speak of an incomplete blockade of the His bundle. Diagnosis of these conduction disturbances is possible with the help of an ECG.
Often, pathological processes immediately affect two or three branches of the bundle, then they talk about a two-beam and three-beam ventricular block. Diagnosis of complex ventricular pathology during a standard ECG is difficult and requires the registration of additional leads.
If the blockage of the bundle of His is incomplete and affects only one branch, then, as a rule, it does not cause serious problems for the patient and he continues to live with such changes for a long time, taking medication.
But in some cases, the disease progresses and transforms into a transverse intraventricular block. With this pathology, the function of the conduction of the His bundle in the transmission of an impulse along the ventricular system is completely lost. The atria and ventricles begin to contract independently.
There are two types of transverse intraventricular blockade:
- Incomplete transverse blockade (Mobitsa). On the ECG, an extraordinary atrial contraction is periodically noted. As a rule, the process quickly proceeds to the next stage, so it is rare to register this type of pathology on the ECG.
- Complete transverse blockade (Trifascicular). The atria and ventricles contract independently of each other, each with its own frequency. ECG complexes that record the work of the ventricular system are deformed.
When the atria and ventricles begin to contract inconsistently and each with its own frequency, the work of the heart becomes ineffective. As a result, it does not provide proper blood flow through the vessels. There is stagnation of blood in the small and large circles of blood circulation, the nutrition of tissues with oxygen and nutrients is disrupted. Vital products are poorly excreted from the organs. Heart failure develops.
Medications can improve heart function, but to achieve a significant effect in this way is possible only with a mild violation of ventricular conduction and in the early stages.
If a complete transverse heart block develops, the only treatment option is the setting of a pacemaker – an artificial pacemaker.
Symptoms of the disease
It is possible to suspect a violation of intraventricular conduction in a child and an adult when the following problems are detected:
- palpitations become more frequent – tachycardia detected;
- heart rate skips beats;
- cardiac muscle contraction chaotic;
- heart pains like angina pectoris;
- shortness of breath, fainting, dizziness – poor blood supply to the brain.
Suspicions of impaired intraventricular conduction in adults and children can cause the following health problems:
- palpitations – tachycardia;
- skipping beats in a heart rhythm;
- the heart muscle contracts randomly;
- heart pain (similar to angina pectoris);
- poor circulation of the brain, due to which there may be shortness of breath dizziness, fainting.
The main characteristic that indicates the appearance of a violation is cardiac blockade.
If such symptoms bother you, you should immediately contact a specialist and sign up for a check, where the diagnosis can be refuted or confirmed, depending on what the cardiac ECG shows and other tests.
Blockade on the right leg of the heart leads to expansion and deformation (the appearance of chipping) in the QRS complex. Such changes are determined through the right chest leads.
The blockade of the left leg of the heart also expands and deforms the QRS, but pathological signs are detected through the left chest leads. If the left anterior branch is affected, then a deviation of the electrical axis of the heart to the left is observed. The diagnosis can be confirmed by comparing the ECG waves – in the second and third leads S will be higher than R. If the pulses do not go through the left posterior branch, then the axis deviates to the right, S is higher than R in the first lead.
Particularly noteworthy are cardiac blockades of a non-specific format. ECG reveals changes that do not correspond to a specific pathology. For example, the QRS complex changes – it splits and deforms without expansion. Such symptoms are noted with local damage to the heart tissue against a background of a heart attack, inflammatory process, etc.
Additional information is provided by such research methods:
- cardiac echocardiography;
- radiography of the lungs;
- functional tests;
- CT scan.
We obtain significant information on the work of the heart muscle during Holter ECG monitoring. The study lasts 24 hours. This method allows you to continuously record signals and identify abnormalities that are not visible on a regular cardiogram. On such a record, changes are noted that occur not only at rest, but also during movement, physical activity. The compact recorder is attached to the belt. The patient leads a familiar lifestyle, and the system captures the work of the heart in a continuous mode.
It is very important to make timely preventive measures to strengthen the vascular system, even if you have not found a violation of intraventricular conduction. What does this give? First reduces the risk of disease. It is better to prevent any disturbance in the body than to fight it. The main measures to be followed by people at any age:
- Walking in the fresh air is a guarantee of a good blood supply to all vital organs, including the heart. Fresh air oxygenates tissues and cells.
- A balanced diet enriched with potassium and vitamins. In general, eating healthy food adds strength, energy and health.
- Compliance with the daily regimen – if you get enough sleep, eat at the same time, you feel much better, and the risk of disease becomes much lower.
- Non-intensive physical activity, which is very important – daily. Easy jogging, gymnastics, exercises, yoga.
- The use of power sports, especially bodybuilding, is undesirable; it rather negatively affects the heart vessels.
- No matter how trite, less stress and worries. Constant emotional stress is detrimental to the heart muscle.
- Annual vacation at sea. If there is such an opportunity, then it should definitely be used. A two-week trip to pure, salty, mineral-enriched water restores both the physical and psychological state of a person. If you can’t go to the sea, you just need to arrange your own outdoor recreation. A trip to the forest will be a worthy alternative to the sea breeze.
- Timely examination at a medical facility. It is better not to ignore even the slightest discomfort when it comes to the health of the heart muscle.
No wonder the heart muscle is called the motor. It regulates most of the processes and supplies the vital organs with blood. The heart should be treated with special trepidation. While it beats and does not bother, we sometimes do not attach due importance to its little motor. But everyone knows if health problems happen, including a violation of intraventricular conduction, which is just out of balance. Therefore, it would be better not to run your health.
It is worth treating the heart with special trepidation. While it beats and does not bother, we sometimes do not attach due importance to our motor.
But everyone knows if there are health problems, including a violation of intraventricular conduction, which is simply unbalancing. Therefore, it would be much better not to start your health.
Even in the absence of intraventricular conduction disturbances, prophylaxis is necessary in a timely manner to reduce the risk of disease. The main measures to prevent pathology in people of any age will be walks in the fresh air.
This is the key to good blood circulation and oxygen supply to all tissues and cells of the body. You need to eat food that is enriched with vitamins and potassium.
The only way to reduce the risk of disease remains a healthy lifestyle. Do not start heart pathologies, as well as overdose with drugs. Constantly, when the corresponding symptom appears, go to the therapist and cardiologist.
There are no special preventive measures to prevent diseases. The only recommendation to reduce the risk of developing cardiac conduction pathology is a healthy and active lifestyle, prevention of drug overdoses, timely visits to a cardiologist and general practitioner.
Myocardial conduction system
To understand exactly how such pathological conditions develop, you need to know what exactly the conductive system consists of, which is responsible for transmitting impulses through the ventricles. So, the leading role in this process belongs to the so-called bundle of His, consisting of two structural parts:
- Left leg. It is represented by the anterior and posterior branches, each of which is responsible for its wall in the left ventricle. Their branches form a system of Purkinje fibers.
- Right foot. It is represented by one bundle branching in the lower parts of the right ventricle.
For the occurrence of excitation in the ventricles, an impulse from the pacemaker passes through the interventricular septum and then the simultaneous excitation of both ventricles occurs. For this to happen, the pulse needs approximately 0,12 seconds.
In the event that blockages are noted on one of the paths, not only the path along which the impulse passes, but also the time during which the ventricles are excited, changes.
Elements of the conduction system of the heart
The intraventricular conduction system is an integral part of the conduction system of the heart. The main function of the system is to conduct an impulse from the place of its formation to the final destination. Normally, formed in the sinus node (SU), an electrical impulse runs from the atria to the ventricles, alternately exciting them. So, first the right and left atria are excited, then the right and left ventricle. Each chamber of the heart has its own time for receiving a charge.
It departs from the atrioventricular node and is located at the junction of the right fibrous triangle with the upper membranous part of the interventricular septum. Its length is from 8 to 20 mm, and the width is only 2-3 mm. After passing some distance from its beginning, the bundle of His is divided into right and left legs.
In order for the blood to flow to organs and tissues, the heart is constantly contracting, creating pressure in the vessels and causing the blood to move.
The contraction of the heart muscle occurs under the influence of electronic impulses, which are generated by the heart’s own conducting system, transferring the discharge across the entire surface of the myocardium.
The system is an electric circuit created from special cells that can create electricity and conduct it. The chain begins in the right atrium from the sinus node. This node is the main one in the conducting system and normally it is it that generates the initial impulse that triggers the contraction of the myocardium.
From the sinus node, through the conductive fibers, electrical excitation is transmitted to the next atrioventricular node in the hierarchical structure, which is located in the lower medial region of the right atrium and smoothly passes to the third node – the bundle of His. The bundle of His is divided into three parts: the right, left front and left hind legs, which in turn are repeatedly divided, forming a ventricular electrical network of thin fibers (Purkinje fibers). Purkinje fibers with their endings, like electrodes, end in the muscle cells of the ventricular part of the heart.
The electrical circuit of a conductive system works on the same principle as a conventional electrical circuit: if, for various reasons, a conductivity violation occurs along its length, then the pulse does not pass further. There is a blockade. Parts of the heart below the incident do not receive electrical stimulation. Thus, the connection in the work of the atria and ventricular myocytes is lost. Diagnosis is by ECG.
Having contracted, the atria push blood into the ventricles. At a time when the ventricles are preparing to expel blood into large vessels to deliver it to the entire body, the atria are “stocked” with a new portion of blood in order to give it to the ventricles. The intraventricular conduction system is represented by conduction paths that form the so-called bundle of His (GH). This bundle collects in itself all the pathways going from the atria.
The mechanism of conduction disturbance: when incomplete, an electrical impulse follows from the atria into the ventricles along one of the branches (less affected). In this case, signs of atrioventricular block are detected. Complete blockade is characterized by a third degree of atrioventricular obstruction and an altered source of ventricular rhythm.
The reasons are severe organic myocardial lesions already listed above.
The shape of the teeth indicates the type of intraventricular block
Organic Causes of Conductivity Disorders
From 0,06 to 0,10 seconds are given for conducting an impulse along the ventricular system. If there is some kind of obstacle, then the impulse passes with delay. If the transmission of an impulse is blocked along all fibers, they speak of complete blockade. If part of the fibers of the conductive intraventricular system nevertheless transmits an impulse, they speak of incomplete blockade. The reasons for the delay or blocking of the transmission of the pulse can be both functional and organic in nature.
Functional nature means failure of deviations in the normal conductivity of the pulse without structural changes in the elements of the conducting system. With organic conduction disturbance, the impulse cannot pass freely due to the restructuring of the conduction pathway as a result of a previous or existing disease.
Organic causes: coronary heart disease (myocardial infarction), abnormalities in the development of the cardiovascular system, heart defects, hypertension, cardiomyopathies, pulmonary heart, diabetes mellitus, dystrophic changes due to systemic diseases (amyloidosis, sarcoidosis). A separate item is the more rare cases of idiopathic blockade, when the cause cannot be identified. Such blockades are called Lenegra disease, Lev disease, etc.
Organic: the development of connective tissue in the area of necrosis after a myocardial infarction or inflammatory process of the heart muscle, abnormalities in the development of the heart, dystrophic changes in muscle fibers due to the pathology of other organs. Such factors lead to a persistent violation of the conductivity function.
Functional: disturbances as a result of external factors, for example, physical exertion, diet, psycho-emotional overstrain, taking certain medications (overdose of cardiac glycosides or opiates). Pathology is often reversible and eliminated along with external factors.
Organic: the development of connective tissue in the area of necrosis after a myocardial infarction or inflammatory process of the heart muscle, abnormalities in the development of the heart, dystrophic changes in muscle fibers due to the pathology of other organs. Such factors lead to a persistent violation of the conductivity function.
The causes of conduction pathologies in a child, during pregnancy and in other cases are different. Of particular note is the age of the patient or person in need of diagnosis. Acute forms of the disease appear in people over forty years of age for the following reasons:
- cardiac ischemia;
- myocardial infarction;
- pathologies associated with cardiomyopathy;
- benign tumors of fibrous connective tissue, or fibroma;
- tumors or metastases in the region of the heart;
- manifestations of angina pectoris;
- high degree of hypothermia.
Non-specific disturbance of intraventricular conduction in young people occurs after an acute form of myocarditis. Often a failure of the atrioventricular inner conduction nerve, its passage is rheumatic. The causes of the disease in young people are as follows:
- violation of ventricular conduction in the form of functional blockades;
- various types of heart disease;
- unauthorized use of glycosides, beta-blockers, potassium salts, antiarrhythmic drugs, drug overdoses;
- increased tone of the vagus nerve;
- deposition of iron or calcium oxalates;
- injuries and bruises of the chest cavity;
- heart surgery and more.
In childhood, conducting a cardiac examination on an ECG can show an AV blockade, which manifests itself from birth and does not depend on experienced rheumatism and other external factors. Complete primary blockade – local disturbances in intraventricular conduction, which require surgical intervention.
Insufficient atrial conduction:
- congenital heart defects;
- rheumatic fever;
- glycoside poisoning.
Violation of intraventricular conduction of the heart:
- open oval window (found in children);
- heart ischemia;
- myocardial hypertrophy;
- diseases of the bronchi and lungs;
- defects of valves.
Insufficient conductivity of the sinus node:
- heart hypertrophy;
- overdose of antiarrhythmic drugs;
Violation of cardiac conduction in the atrioventricular node:
- acute stage of myocardial infarction;
- congenital malformations of the body;
- overdose of hormonal drugs.
Currently, heart diseases are quite common, and among them are especially associated with impaired heart rhythm caused by conduction pathology inside the ventricles of the heart.
How is ECG conductivity different?
Signs of impaired conduction depend on the type of blockade. They differ in:
- the direction of the electrical axis of the heart;
- the form of ventricular complexes;
- place in the chest and standard leads;
- the width of the teeth and the intervals.
Sometimes changes in the ventricular complexes are not considered specific, since they are also present in cases of acute pulmonary heart and right ventricular hyperfunction. Transient blockade simulates ventricular extrasystole.
The two-beam type of blockade is regarded as a harbinger of the development of a three-beam lesion. In the three-beam variant, the shape of the ventricular complexes depends on the location of the lesion, while partially maintaining conduction in one of the branches resembles the variants of two-beam blockades. The ECG picture is superimposed on atrioventricular disorders of varying severity.
When assessing the features of blockades for a doctor, it is important to look at previous ECGs to be sure of the age of changes.
According to the localization of the process, these types of blockade are distinguished:
- Single beam – signal delay is recorded only in one of the beam branches. Accordingly, a blockage of the right ventricle or a violation in the work of the left is detected.
- Two-beam – two branches do not function – both left legs or one left and right.
- Three-beam – pulse delay is noted in all three branches.
Patient M., 65 years old, was admitted to the therapeutic department. At the time of examination, he complains of shortness of breath during physical exertion, frequent bouts of dizziness, general weakness. Repeatedly there were a loss of consciousness.
During the survey, it was possible to find out that such symptoms disturb her for more than a year. Over 14 months, marked weakness, headaches, dizziness were noted. For six months, there were loss of consciousness – about once a week. In the last month, fainting occurs almost daily. The patient faints for one minute, then general weakness is noted.
Upon further examination, changes were detected on the ECG. Ultrasound, dopplerography, left ventricular failure, valvular stenosis. Diagnosis: Coronary heart disease; rhythm disturbance as a two-beam blockade and MAC attacks; heart failure I tbsp.
The patient was given a pacemaker, her condition improved, and she was discharged.
The nature of the violations distinguishes:
- Incomplete blockade. Impulse conduction is slow, but it is preserved. Excitation of the myocardium occurs due to intact branches. This condition happens in healthy people, but it can also indicate pathology. Changes are usually detected by chance on an ECG. There are no complaints in patients, sometimes there is general weakness, increased fatigue.
- Complete blockade. Impulses do not reach the lower parts of the ventricles. High probability of cardiac arrest on the background of bradycardia. This condition is accompanied by clear clinical symptoms.
According to the type of violations, there are:
- Focal changes – observed in separate parts of the myocardium closer to Purkinje fibers, the impulse partially passes through the ventricles.
- Arborization changes – signal transmission is stored in all parts of the conducting system, except its end sections.
- One, two, or three-beam. This is determined by how many beams are involved in the incorrect conduct of pulses.
- Local. Violation of the conduction is not observed in all leads during ECG examination.
- Carryover. Improper impulse conduction alternates with normal.
- Arborization. Impulse blockade occurs in Purkinje fibers. More precisely, in their lower sections.
- Complete blockades.
- Incomplete blockades.
- Alternating blockades. When conducting research, one or the other option is revealed.
Single beam (monofascicular) – one beam is partially or completely blocked. This can be a blockade of the right leg of the bundle of His, anterior or posterior branch of the left leg.
Two-kidney (bifascicular) – two beams are involved in the process. It can be the left leg, so it consists of two bundles: the front and rear branches; the right leg and the front or rear branch of the left leg.
Three-beam (trifascicular) – completely blocked the left leg and partially right leg, complete blockade of the right leg and incomplete blockade of the front and rear branches of the left leg.
Types of heart block
Depending on how difficult the impulse passage through the legs of His is, a complete and incomplete blockade of the legs of the bundle of His is isolated. If the changes are permanent, the blockade is called a stand. If the blockade appears under the influence of certain factors, they speak of a transient blockade. There is also a classification that distinguishes conduction disturbances depending on the number of beams involved. In Latin, the sheaf is spelled “fasciculus”, therefore the synonym for sheaf is the adjective “fasciculus”.
How to determine the prognosis for impaired conductivity?
Since the pathology of conduction is not isolated, but is a consequence of other diseases, prediction is permissible only taking into account the clinical course, the effectiveness of treatment of the underlying disease.
Blockade of the left bundle branch block increases the risk of death by 5 times. The right leg block is not considered a risk factor for heart disease.
Two-beam disorders precede the transition to complete atrioventricular blockade annually in 5% of patients. Fear of increasing conductivity should be with an intermittent type of change.
If blockades arose in the acute stage of myocardial infarction, then mortality increases to 50%. This indicates a common focus of necrosis.
Intraventricular conduction cannot be considered in isolation from all cardiac pathology. The type of blockade is important in the diagnosis, purpose and choice of treatment.
In the event that the blockade of the legs of the bundle of His is asymptomatic, the prognosis is most often favorable. Such patients do not need to undergo treatment measures. It is only important to observe the dynamics of changes at the cardiologist. This will help to identify organic lesions in a timely manner.
It should be noted that blockades are one of the prognostic factors in the course of major diseases. So, you need to highlight the following points:
- Blockade of the left leg increases the mortality of cardiac pathologies by 5 times.
- In the event that blockades occur against a background of myocardial infarction, this indicates a large area of necrosis. In this case, mortality can reach 50%.
- Blockade of the right leg is not considered a risk factor for cardiac pathologies.
In any case, any disease is easier to prevent than to treat. As already mentioned, conduction disorders by themselves do not harm a healthy person. Therefore, to prevent the development of serious pathologies, it is important to carefully monitor yourself. Eliminate bad habits, do not lead a sedentary lifestyle, and also follow a diet. All this will help prevent diseases that can lead to the appearance of blocks for conducting an impulse to the ventricles.
The prognosis of existing conduction disturbances differs sharply depending on what caused this disorder. Patients with two- and three-beam blockade have a risk of developing complete atrioventricular blockade and ventricular rhythm disturbances. They also constitute a risk of sudden cardiac death of the patient.
5 Conductivity disorder in children
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Conductivity disorders in children may disappear as they grow older. In other situations, the disorder may become chronic. The reasons for the development of ventricular conduction disturbances in children can be the following:
- premature babies
- hypoxia of the heart muscle,
- birth injury,
- Congenital heart disease
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- infectious endocarditis,
- rheumatism and others
Establishment of the cause and treatment
Treatment of intraventricular blockade in both adults and children begins with the establishment of the cause. If the identified causes are functional, then, as a rule, their elimination leads to a complete recovery of the patient.
If a disease was the cause of this kind of conduction disturbance, then the treatment is aimed at the underlying disease. Drugs are prescribed or adjusted for arterial hypertension (AH), coronary heart disease, etc.
Attention is also paid to the issues of a therapeutic diet.
In the case of ineffective drug treatment, severe clinical symptoms, the patient is implanted with a device that artificially stimulates the ventricular myocardium.
Cardiovascular diseases are in first place in frequency of occurrence and causes of mortality. Heart diseases significantly reduce the quality of life, cause deterioration in the work of other organs. Cardiovascular disease is an extensive group of pathologies. A significant place in it is occupied by violations of intraventricular conduction.
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