In a healthy person, the heart rate should normally be from 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 get enough oxygen. The 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. Atrioventricular block, which interferes with the normal transmission of signals, can cause impaired blood flow through the vessels.
Description of the problem
The AV node, which acts as 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 decreases 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 to the legs of the bundle and only then to the ventricles, causing them to contract. Such a well-coordinated process ensures stable blood flow.
Atrioventricular block (AVB) is a type of disorder for conducting signals from the atria through the atrioventricular node to the ventricles. This pathology becomes the cause of heart rhythm disturbances and disorders of blood flow through the vessels. In this case, electrical impulses can be transmitted very slowly or completely cease their passage. The atrioventricular block in ICD 10 has numbers 144.0, 144.1, 144.2 and 144.3, which includes atrioventricular block 1, 2 and 3 degrees, as well as another, unspecified block.
The disease is associated with damage to the atrioventricular node, bundle or legs of the bundle of His. Doctors have established a pattern: the lower the area of the disorder, the harder the disease progresses, provoking unfavorable prognoses. In 17% of cases, death is possible.
Epidemiology
Most often, the named 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 mildly recorded in 2% of cases from all patients. Severe heart block occurs after the age of seventy. Sometimes a moderate pathology is also diagnosed in people who do not have heart disease, this is especially true in athletes. And in 3% of cases, the disease develops due to the use of certain medications. Complete atrioventricular block with subsequent death is diagnosed in 17% of cases.
The severity of the pathology
In medicine, it is customary to distinguish the following severities of the named disease:
1. Atrioventricular block 1 degree is characterized by a slowdown in the conductivity of impulses that still reach the ventricles. This pathology is most often detected by chance during an ECG. This stage of the disease does not require therapy, but the patient should carefully use medications that reduce the heart rate to prevent the development of a more severe form of the disease. This degree of ailment is diagnosed in young people, in particular in athletes.
2. Atrioventricular blockade of the 2nd degree is caused by a violation of conductivity, in which only part of the electrical signals is carried out. There are several types of AV blockade of the second degree:
- The first type, in which a person’s condition worsens depending on the duration of the signal delay. If untreated, complete heart block and death occurs.
- Sudden signal delay, in which there is no conduction of every second or third impulse.
3. Grade 3 atrioventricular block is characterized by complete heart block, in which the impulse conduction ceases, the ventricles begin to contract in their own rhythm. All this contributes to circulatory disorders. If untreated, death occurs.
When diagnosing blockages of the first or second degree, they speak of such a pathology as incomplete atrioventricular block. 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 conductivity of signals are observed in the bundles of His.
- Proximal blockade, which is characterized by abnormalities in the atria and AV node.
- Combined AV blockade. It is caused by the presence of multilevel impulse conduction disturbances.
In addition, there are several forms of pathology:
- Acute blockade resulting from myocardial infarction or as a result of the use of certain medications.
- Intermittent atrioventricular block, developing with ischemia and coronary insufficiency.
- Chronic blockade.
Causes of the disease
In some cases, atrioventricular block 1 degree is also diagnosed in healthy people who do not suffer from heart pathologies. It can also be detected in patients with hypotonic type VSD. Usually the disease does not show any signs and goes away on its own. But in the case of preserving the pathology for a long period of time, they say that a person has serious heart problems.
Atrioventricular block 2 degrees, as well as the third, most often indicates the development in humans of an organic heart lesion. These include the following diseases:
- Myocardial infarction, in which disturbances in signal conduction occur due to dead and damaged tissue.
- Heart defects. In this case, a deep disorder of the structure of the heart muscle is observed.
- Ischemia, in which myocardial hypoxia is observed, a decrease in muscle functionality.
- Prolonged hypertension, which leads to the development of 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, hypothyroidism, gastric ulcer, intoxication, infectious diseases, head injury 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 block is diagnosed, in which some parts of the conduction system are absent. Usually pathology is accompanied by other congenital anomalies.
Often the development of the disease provokes intoxication of the body with medications, such as calcium channel blockers or lithium salts.
Symptoms and signs of the disease
Congenital atrioventricular block in children and adolescents is asymptomatic. At the first degree of the disease, there are no symptoms of blockade. Patients can only complain of fatigue, weakness, slight dizziness, tinnitus, flickering points in front of the eyes, or a feeling of lack of air during physical activity. Especially often, this phenomenon is observed when running, since heart block prevents the full flow of blood to the brain.
With blockade of the second and third degree, a violation of the heartbeat (bradycardia) is observed. The disease is characterized by a sudden onset of weakness, dizziness, and heart rhythm disorder. In case of impassability of impulses to the ventricles, cramps occur, loss of consciousness for several minutes. This phenomenon in medicine is called an MES attack, it is very dangerous, as it can provoke a complete cardiac arrest. But this is rare, usually the patient regains consciousness, and this contributes to the inclusion of workarounds for conducting impulses.
Doctors recommend an examination. If a person has cases of MES, then such a patient should be hospitalized. In rare cases, when after an attack the patient never regains consciousness, emergency medical care is required.
Complications and consequences
With heart block, complications arise in the form of a slowdown in heart rate against a background of damage to an organ of an organic nature. Most often, AV blockade leads to chronic heart failure, arrhythmias, tachycardia. The course of the disease is often complicated by MES attacks, which can result in death as a result of cardiac arrest. Repeated MES attacks in old age cause the development of the syndrome of intellectual and mnestic disorders. Rarely, cardiogenic shock, collapse, encephalopathy can also be observed.
Diagnostic measures
Diagnosis of the disease begins with a history and examination of the patient. The survey determines the presence of cardiopathy, the facts of the use of medications that affect the rhythm of the heart. When listening to an organ, a specialist notes the loss of ventricular contractions, bradycardia. Then the doctor directs the patient to an electrocardiogram.
Atrioventricular block on ECG can be detected even without the presence of symptoms. This technique makes it possible to identify the degree of development of pathology. For 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 make it possible to make an accurate diagnosis and develop treatment tactics.
Therapies
Atrioventricular blockade of treatment requires only if 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 the use of drugs, the doctor reduces their dosage or completely cancels. In case of blockade as a result of organic damage to the heart, for example, with a heart attack or myocarditis, the doctor carries out therapy with special medicines, and in the future, the establishment of a pacemaker may be required.
With the development of an MES attack, first aid must be provided by 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 block. In the chronic form of blockade, therapy is performed using Theophylline.
Usually, conservative treatment of the underlying disease can completely restore conduction along the atrioventricular node. But sometimes a scar formed in its area leads to a persistent disorder in the conductivity of the signals. In this case, the patient requires the establishment of an artificial pacemaker. Also, an indication for this operation is the presence of MES attacks, chronic bradycardia, heart block of the second degree of the second type or third degree, accompanied by angina pectoris, heart failure or hypertension. This surgical treatment increases the patient's chances of full recovery and improves the quality of life.
Forecast
First-degree AV block has good predictions. With the right treatment for the second and third degree of the disease, the risk of developing complications is significantly reduced, and the person's life expectancy increases. The installation of an artificial pacemaker makes it possible to improve the quality of life of patients and increase their survival. But in some cases, third-degree heart block leads to the development of persistent heart failure and even death.
Prevention
Typically, AV blockade is due to the presence of a underlying disease or pathological condition, so its prevention is primarily aimed at treating diseases of the cardiovascular system and eliminating the long-term use of medications that have a negative effect on heart rhythm.
Complications are prevented by measures that are aimed at preventing the development of severe heart pathologies, therefore, doctors recommend timely contact a medical institution for diagnosis and the appointment of 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 more favorable prognoses than acquired throughout life.
Atrioventricular block is a serious pathology that is easier to prevent than to treat later. In case of deterioration of well-being, a person should undergo regular examinations by a cardiologist, and when making a diagnosis - follow all doctor's prescriptions.
Doctors insist on the regular use of trace elements such as magnesium and potassium, contributing to the support in the normal state of the heart muscle. In addition, a person should eat right, eliminate bad habits and the use of certain groups of medicines. For any manifestations of the disease, consult a doctor.