Violation of intraventricular conduction is a pathology in which the conduction of an electrical impulse through the ventricles slows down or stops. The rhythm and frequency of contractions changes, their strength decreases. As the disease progresses, the heart may stop. Timely diagnosis and rationally selected treatment reduce the likelihood of complications and prolong life.
What it is
Normally, the impulse originates in the sinus node of the right atrium - where the superior vena cava flows into it. Further, the wave goes along the atria and is at the next control point - the node of the atrioventricular localization. From here, excitement goes through the bundle of His and gradually spreads to the apex.
His fibers are special cells of the interventricular septum that form three branches. The right leg (RNPG) delivers signals to the walls of the right ventricle. On the left (LNPG), which is divided into anterior and posterior branches, there is coverage of the left ventricle. At the end, the branches are divided into Purkinje fibers. This structure allows you to conduct an impulse without loss and ensures the smooth functioning of the heart.
Conduction is slowed down and broken - is there a difference?
In a healthy organ, impulses move from top to bottom in a set rhythm, with the required speed. With pathology, their conduct is slowed down or disrupted. If the signal is inhibited, the excitation reaches the end point, but this process is slower. If the conduction is violated, the impulse is interrupted in a certain area or is completely absent.
Violation and retardation of intraventricular conduction occurs at different ages. We cannot unequivocally assess how often this pathology is detected. Failure in the cardiac conduction system often remains asymptomatic and is recorded accidentally during a preventive examination. According to the medical literature, various types of conduction disturbances are diagnosed mainly after 50 years (5–7% of cases). In 60–70 years, the detection rate of such conditions reaches 30%.
Failure of intraventricular conduction belongs to the group of bradyarrhythmias. Intra-atrial conduction disorders belong to the same category. The causes and symptoms of the development of these conditions are similar. An accurate diagnosis can be made only after an examination.
The reasons for the development of pathology
All possible causes of failure can be divided into two large groups: cardiac - caused by cardiac pathology and non-cardiac - provoked by other disorders.
Cardiac factors:
- heart defects;
- myocardial infarction;
- myocarditis;
- cardiac ischemia;
- cardiomyopathy;
- atherosclerosis of the coronary vessels;
- the consequences of previous surgical interventions (for example, due to valve replacement, radiofrequency catheter ablation).
Noncardiac factors:
- vegetative-vascular dystonia;
- endocrine problems: hypothyroidism, sugar diabetes;
- respiratory system disorders with tissue hypoxia - bronchospasm, chronic inflammation;
- irrational intake of medications;
- arterial hypertension;
- alcohol poisoning;
- taking drugs;
- pregnancy.
A signal failure does not always indicate pathology. For example, partial conduction disturbance along the right bundle branch 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 "problems" are revealed against the background of physical exertion (for example, training and competition). If the situation returns to normal after rest, 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.
Symptoms: what most often worries a person
Failure of intraventricular conduction has no specific symptoms. Often this condition remains unrecognized for a long time. The patient does not complain about anything, and the problem is revealed by chance - during medical examination, undergoing a medical examination before starting work or study, serving in the army, before an operation, etc.
Possible signs of pathology:
- feeling of "freezing" in the chest;
- interruptions in the work of the heart - the appearance of extraordinary contractions;
- slowing down the heart rate;
- dyspnea;
- feeling short of breath;
- dizziness;
- anxiety, anxiety.
With the progression of the process, Morgagni-Adams-Stokes syndrome (MAS) develops. At the beginning of the attack, the patient turns pale and loses consciousness. After improvement of the condition, the reddening of the skin persists. These episodes last 1–2 minutes and are caused by insufficient blood supply to the brain against the background of a sharp decrease in cardiac output. Neurological complications are usually not observed.
Classification
According to the localization of the process, the following types of blockade are distinguished:
- Single-beam - signal delay is recorded only in one of the beam branches. Accordingly, a blockade of the right ventricle or disturbances in the work of the left are detected.
- Two-bundle - two branches do not function - both left legs or one left and right.
- Three-beam - pulse delay is observed in all three branches.
Clinical case
Patient M., 65 years old, was admitted to the therapeutic department. At the time of examination, he complains of shortness of breath during exertion, frequent bouts of dizziness, general weakness. Repeatedly there were loss of consciousness.
During the survey, it was found out that such symptoms bother her for more than a year. Over the course of 14 months, severe weakness, headaches, and dizziness have been noted. For six months, there were loss of consciousness - about once a week. In the last month, fainting occurs almost daily. The patient loses consciousness for one minute, then general weakness is noted.
During follow-up examination, changes in the ECG were found. An ultrasound scan, Doppler sonography, revealed left ventricular failure, valvular stenosis. Diagnosis: Ischemic heart disease; rhythm disturbance by the type of two-beam blockade and attacks of MAC; heart failure I st.
The patient was fitted with a pacemaker, her condition improved and she was discharged.
By the nature of the violations, they are distinguished:
- Incomplete blockade. The impulse conduction is slow, but it is retained. Excitation of the myocardium occurs due to intact branches. This condition occurs in healthy people, but it can also indicate a pathology. Changes are usually detected by chance on an ECG. Patients have no complaints, sometimes there is general weakness, increased fatigue.
- Complete blockade. The impulses do not reach the lower ventricles. There is a high probability of cardiac arrest on the background of bradycardia. This condition is accompanied by obvious clinical symptoms.
By the type of violations, there are:
- Focal changes are observed in certain areas of the myocardium closer to the Purkinje fibers, the impulse partially passes through the ventricles.
- Arborization changes - signal transmission is preserved in all parts of the conducting system, except for its end sections.
Diagnosis: ECG and Holter signs
Electrocardiography is the main method for diagnosing a pathological process. Violation of intraventricular conduction on the ECG will manifest with specific signs.
A right pedicle block leads to widening and deformity (chipping) in the QRS complex. Such changes are determined through the right chest leads.
Left-sided blockade also widens and deforms the QRS, but pathological signs are detected through the left chest leads. If the left anterior branch is affected, then there is a deviation of the electrical axis of the heart to the left. You can confirm the diagnosis by comparing the ECG waves - in the second and third leads, S will be higher than R. If the impulses do not go through the left posterior branch, then the axis deviates to the right, S is higher than R in the first lead.
Cardiac blockade of a nonspecific format deserves special attention. The 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 observed with local damage to the tissues of the heart against the background of a heart attack, inflammatory process, etc.
Additional information is provided by the following research methods:
- echocardiography of the heart;
- X-ray of the lungs;
- functional tests;
- CT scan.
We obtain significant information about the work of the heart muscle during Holter ECG monitoring. The research lasts 24 hours. This method allows you to make continuous registration of signals and identify violations that are not visible on a conventional 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 normal life, and the system records the work of the heart in a continuous mode.
It is important to understand: the success of the diagnosis will directly depend on whether the blockade is permanent or transient and how often attacks occur in the latter case. If conduction disturbances are noted daily, daily monitoring will reveal this on the ECG. Sometimes it is required to control the cardiogram lasting 7-30 days.
Treatment principles
Moderate conduction disturbances do not require treatment. Incomplete blockage in the right branch of the His bundle is not dangerous. In this situation, we recommend that you see a cardiologist, undergo an annual examination by a doctor and do an EKG. But this is if the patient has no other complaints or concomitant pathology. If deviations are detected, appropriate therapy is indicated.
Left ventricular block is more dangerous. Against its background, violations of blood flow and heart failure develop more often. We recommend taking cardiac glycosides, antiarrhythmic and other drugs. The therapy regimen is determined individually based on the severity of the condition, the patient's age, and concomitant diseases.
It is important to know: a specific treatment for intraventricular blockade has not been developed. The proposed drugs only increase the excitation of the heart tissues, but do not eliminate the cause. It is necessary to treat the underlying pathology - the one that caused the failure of the conducting system. This is the only way to slow down the progression of the disease.
If drug therapy is ineffective or the patient's condition is severe, surgical treatment is suggested. A pacemaker is being installed - a device that imposes its own rhythm of the heart. The implanted device ensures uninterrupted activity of the myocardium.
Expert advice: when they put a pacemaker
Pacemaker insertion is a surgical procedure and is only prescribed if indicated. It makes no sense to carry out the procedure in the absence of obvious symptoms of pathology. If the patient is doing well, an artificial pacemaker is not indicated. The operation is not recommended if the identified symptoms are associated with reversible causes. It is necessary to cope with the underlying disease - and the heart muscle will be able to work fully again.
Indications for installing a pacemaker:
- bradycardia with a heart rate of less than 40 beats / min and rhythm disturbances in the presence of obvious symptoms;
- complications that threaten the patient's life;
- attacks of MAC;
- persistent conduction disturbances after myocardial infarction.
The possibility of installing a pacemaker with a pulse rate of less than 40 beats / min in the absence of obvious clinical symptoms is discussed. The procedure is performed at any age.
Prevention of cardiac conduction disorders has not yet been developed. Don't delay treatment, avoid risk factors. This will reduce the chances of developing pathology. In order to identify the problem in time, regularly undergo preventive examinations with a therapist with an ECG assessment (as needed).
