A he althy person should have a normal heart rate of sixty to eighty times per minute. This rhythm allows the vessels to fill with blood at the time of the contraction of the heart, so that the internal organs have the opportunity to receive a sufficient amount of oxygen. Normal conduction of impulses is ensured by the grouped activity of myocardial fibers. Electrical impulses originate in the sinus node, they are transmitted through the heart fibers to the atrioventricular node (AV node), and then through the ventricular tissue. An atrioventricular block that interferes with normal signaling can cause blood flow problems.
Problem description
The AV node, which is a component of the conduction system of the heart, guarantees sustained contraction of the atria and ventricles. The strength of the electrical signals that come from the sinus node is reduced in the atrioventricular node, which allows the atria to contract and push blood into the ventricles. After a short pause, the signals enter the bundle of His, then tobundle legs and only then to the ventricles, provoking their contraction. Such a well-coordinated process ensures a stable flow of blood.
Atrioventricular blockade (AVB) is one of the types of disorders in the conduction of signals from the atria through the atrioventricular node to the ventricles. This pathology causes a violation of the heart rhythm and a disorder in the movement of blood through the vessels. In this case, electrical impulses can be transmitted very slowly or completely stop their passage. Atrioventricular block in ICD 10 is numbered 144.0, 144.1, 144.2 and 144.3, which includes atrioventricular block of 1, 2 and 3 degrees, as well as other, unspecified block.
The disease is associated with damage to the atrioventricular node, bundle or legs of the bundle of His. Physicians have established a pattern: the lower the area of violation, the more severe the disease, provoking unfavorable prognosis. In 17% of cases, death is possible.
Epidemiology
Most often, this pathology is diagnosed in those who suffer from concomitant diseases of the heart and blood vessels. For example, together with myocardial infarction, it is observed in 13% of cases. Atrioventricular block in children is mild in 2% of all patients. Severe heart block occurs after the age of seventy years. Sometimes pathology of moderate severity is diagnosed in people who do not have heart disease, this is especially true for athletes. And in 3% of cases, the disease develops due to the intake of certainmedical preparations. Complete atrioventricular block followed by death is diagnosed in 17% of cases.
Severity of pathology
In medicine, it is customary to distinguish the following degrees of severity of the named disease:
1. Atrioventricular blockade of the 1st degree is characterized by a slowdown in the conduction of impulses that still reach the ventricles. This pathology is detected most often by chance during an ECG. This stage of the disease does not require therapy, but the patient should use drugs that reduce the heart rate with caution in order to prevent the development of a more severe form of the disease. This degree of illness is diagnosed in young people, in particular athletes.
2. Atrioventricular blockade of the 2nd degree is caused by a violation of conduction, in which only part of the electrical signals are conducted. There are several types of second-degree AV block:
- The first type, in which a person's condition worsens depending on the duration of the signal delay. If left untreated, complete heart block and death occur.
- Sudden delay of signals in which there is no conduction every second or third pulse.
3. Atrioventricular blockade of the 3rd degree is characterized by a complete blockade of the heart, in which the conduction of impulses stops, the ventricles begin to contract in their own rhythm. All this contributes to circulatory disorders. If untreated, fatalexodus.
When diagnosing blockades of the first or second degree, they speak of such a pathology as incomplete atrioventricular blockade. When the third degree of the disease is observed, a complete heart block is diagnosed, which can cause the development of complications and even death.
Varieties of AV blockade
In medicine, other varieties of the described disease are also distinguished:
- Distal blockade, in which disturbances in the conduction of signals are observed in the bundles of His.
- Proximal blockade, which is characterized by abnormalities in the atria and AV node.
- Combined AV block. It is caused by the presence of multi-level disturbances in the conduction of impulses.
In addition, there are several forms of pathology:
- Acute blockade due to myocardial infarction or as a result of the use of certain drugs.
- Intermittent atrioventricular block that develops with ischemia and coronary insufficiency.
- Chronic blockade.
Causes of disease development
In some cases, atrioventricular blockade of the 1st degree is also diagnosed in he althy people who do not suffer from heart pathologies. It can also be detected in patients with hypotonic VSD. Usually the disease does not show any symptoms and goes away on its own. But if the pathology persists for a long period of time, they say that a person has serious heart problems.
Atrioventricularblockade of the 2nd degree, as well as the third, most often indicates the development of an organic heart lesion in a person. These diseases include:
- Myocardial infarction, in which disturbances in the conduction of signals occur due to dead and affected tissue.
- Defects of the heart. In this case, there is a deep disorder in the structure of the heart muscle.
- Ischemia, in which there is myocardial hypoxia, a decrease in muscle functionality.
- Prolonged hypertension leading to cardiomyopathy.
- Cardiosclerosis resulting from myocarditis. In this case, the heart muscle is covered with scars that are not able to conduct impulses.
- Other diseases: diabetes mellitus, hypothyroidism, stomach ulcers, body intoxication, infectious diseases, TBI and others.
Also, the causes of the development of AV blockade can be surgical interventions on the heart: prosthetics, plastic defects, catheterization and others. Very rarely, congenital heart blocks are diagnosed, in which some parts of the conduction system are missing. Usually, the pathology is accompanied by other congenital anomalies.
Often the development of the disease is provoked by intoxication of the body with medications, such as calcium channel blockers or lithium s alts.
Symptoms and signs of illness
Congenital atrioventricular block in childhood and adolescence is asymptomatic. In the first degree of the disease, there are no symptoms of blockade. Patients may only complain of fatigue, weakness, lightdizziness, ringing in the ears, flashing dots before the eyes, or feeling short of breath during physical activity. This phenomenon is especially often observed when running, since heart block prevents proper blood flow to the brain.
When blockade of the second and third degree, there is a violation of the heartbeat (bradycardia). The disease is characterized by sudden onset of weakness, dizziness, heart rhythm disorder. In case of obstruction of impulses to the ventricles, convulsions occur, loss of consciousness for several minutes. This phenomenon in medicine is called an attack of MES, it is very dangerous, as it can provoke a complete cardiac arrest. But this is rare, usually the patient regains consciousness, and this is facilitated by the inclusion of bypass pathways for conducting impulses.
Doctors recommend getting tested. If there is a case of MES in a person, then such a patient should be hospitalized. In rare cases, when after an attack the patient does not regain consciousness, emergency medical care is required.
Complications and consequences
When heart blockade complications occur in the form of a slow heart rate against the background of damage to an organ of an organic nature. Most often, AV blockade leads to chronic heart failure, arrhythmias, and tachycardia. The course of the disease is often complicated by attacks of MES, which can be fatal as a result of cardiac arrest. Multiple attacks of MES in old age causedevelopment of the syndrome of intellectual-mnestic disorders. Rarely, cardiogenic shock, collapse, encephalopathy can also be observed.
Diagnostic measures
Diagnosis of the disease begins with the study of history and examination of the patient. During the survey, the presence of cardiopathies, the facts of the use of medications that affect the heart rhythm are determined. When listening to the organ, the specialist notes the loss of ventricular contractions, bradycardia. The doctor then directs the patient for an electrocardiogram.
Atrioventricular block on ECG can be detected even without symptoms. This technique makes it possible to identify the degree of development of pathology. To make an accurate diagnosis, daily ECG monitoring is often used, which can indicate the cause of the disease.
In addition, an ultrasound of the heart is prescribed to identify the nature of the pathology, as well as Holter monitoring of blood pressure, tests with physical activity and EFI to identify indications for surgical intervention. With concomitant cardiac pathologies, MRI and laboratory tests are often used. Comprehensive diagnostics makes it possible to make an accurate diagnosis and develop therapy tactics.
Therapy Methods
Atrioventricular block requires treatment only when its second or third degree is diagnosed. In the first degree of pathology, only observation of the patient is required. With the development of the disease due to taking medications, the doctor reduces their dosage orcancels completely. In case of blockade as a result of organic damage to the heart, for example, with a heart attack or myocarditis, the doctor conducts therapy with special medications, and in the future it may be necessary to install a pacemaker.
When an attack of MES develops, first aid should be provided using drugs such as Isoprenaline or Atropine. In the case of existing heart failure, drugs in the form of diuretics or glycosides are suggested for atrioventricular blockade. In the chronic form of the blockade, therapy is carried out using "Theophylline".
Usually, conservative treatment of the underlying disease allows you to completely restore conduction through the atrioventricular node. But sometimes a scar that forms in its area leads to a persistent disorder in the conduction of signals. In this case, the patient requires the installation of an artificial pacemaker. Also an indication for this operation is the presence of attacks of MES, chronic bradycardia, second-degree heart block of the second type or third degree, accompanied by angina pectoris, heart failure or hypertension. This surgical treatment increases the patient's chances of a full recovery and improves the quality of life.
Forecast
First degree AV block has a good prognosis. With properly selected treatment of the second and third degree of the disease, the risk of complications is significantly reduced, and a person's life expectancy increases. The installation of an artificial pacemaker makes it possibleimprove the quality of life of patients and increase their survival. But in some cases, third-degree heart block leads to persistent heart failure and even death.
Prevention
Usually, AV blockade is caused by the presence of an underlying disease or pathological condition, so its prevention is aimed primarily at the treatment of diseases of the cardiovascular system and the exclusion of long-term medication that has a negative effect on the heart rhythm.
Prevention of complications are measures that are aimed at preventing the development of severe heart pathologies, so doctors recommend contacting a medical institution in a timely manner for diagnosis and effective therapy. In order to prevent the progression of the disease, it is recommended to implant a pacemaker. The congenital form of the disease has a better prognosis than the acquired form throughout life.
Atrioventricular blockade is a serious pathology that is easier to prevent than to treat later. If the state of he alth worsens, a person should undergo regular examinations by a cardiologist, and when making a diagnosis, follow all the doctor's prescriptions.
Medics insist on the regular use of trace elements such as magnesium and potassium, which contribute to maintaining the normal state of the heart muscle. In addition, a person must eat right, eliminate bad habits and the use of certain groups of medicines. Atany manifestations of the disease should consult a doctor.
