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Av tachycardia. Signs of reciprocal avnodal tachycardia on the ecg. Tachycardia with pulmonary edema

Radiofrequency ablation of the heart (or, as it is also called, catheter ablation) is a very important operation in cardiac surgery. RFA is performed in cases where a person has complicated atrial fibrillation.

This procedure is a minimally invasive treatment because it does not require an incision.

History of origin

RFA began its development in the 80s of the twentieth century. It was then that S. Huang, together with his colleagues, conducted experiments on dogs. They used radiofrequency energy to disrupt the electrical communication between the atria and ventricles. For this purpose, a special catheter was used - an electrode.

The experiments were successful, and already in 1987, catheter ablation was performed on the first patient. From that moment on, the history of the development of ablation began - one of the most effective procedures in eliminating arrhythmia.

Indications for use

Radiofrequency ablation of the heart is not a procedure that a patient can choose for his or her treatment. The doctor decides when exactly this operation should be used. Indications for its implementation:

  • unsatisfactory results when using drug treatment;
  • appearance side effects when taking medications;
  • very high risk of sudden cardiac arrest.

RFA can combat the following diseases:

  • ventricular tachycardia;
  • reciprocal tachycardia;
  • Wolff-Parkinson-White syndrome (WPW syndrome);
  • enlargement of the heart.

Contraindications

The catheter ablation procedure has many contraindications. These include:

  • constantly elevated body temperature;
  • persistent hypertension;
  • lung problems;
  • severe sensitivity to iodine;
  • kidney failure;
  • poor blood clotting.

However, there are also contraindications in which RFA is postponed until remission or complete cure. These include:

  • infectious diseases;
  • fever;
  • anemia.

Preparation for RFA

To ensure that no complications arise after or during RFA, the patient must undergo a series of examinations. These include:

  • blood analysis. It is carried out on the blood group and Rh factor. Tests are also taken to determine the presence or absence of hepatitis B and C and the human immunodeficiency virus. A test for the presence of syphilis is also carried out;
  • stress test;
  • Echo-CG;
  • magnetic resonance imaging of the heart.

If the examination results are positive, a period of RFA can be scheduled. In this case, the doctor prepares the patients by giving them some instructions. Two to three days before the procedure, you will need to stop taking certain medications. This applies to antiarrhythmic drugs, drugs that lower blood sugar, and so on. The patient must stop eating and drinking water 12 hours before the procedure. It is also necessary to shave the areas through which the catheter will be inserted.

Benefits of Catheter Ablation

It is not for nothing that RFA is one of the best procedures in the fight against many heart diseases. Among the advantages over surgical intervention, the following are worth noting.

1. Most patients tolerate this operation very easily. When a patient needs to undergo this procedure, it is safe to say that he will not be in the hospital for more than two or three days. This is a very short period when compared with surgery. During open surgery, the integrity of the human body is damaged, which leads to a long recovery. Therefore, the patient remains in the hospital for more than one week.

2. This procedure is a minimally invasive operation. You do not need to make large incisions to insert the catheter. The required needle is inserted through a small incision in the thigh area.

3. Painless procedure. After a patient undergoes open surgery, he faces terrible pain. To suppress it, he is given painkillers. This is not observed after ablation. A person feels discomfort only during the procedure. The sensation is more uncomfortable than painful. After the procedure is completed, the feeling of chest compression disappears within a few hours. It should be noted that you do not need to take painkillers.

4. Fast recovery after surgery. Within a couple of days after the operation, if the patient’s readings are normal, he can be discharged.

5. Cosmetic effect. After ablation there is no scar left. This is very different from open surgery, which involves making a large incision in the patient's chest and leaving a huge cosmetic defect. Small punctures left after the insertion of catheters heal quickly and completely disappear, leaving no scars behind.

Carrying out the procedure

This procedure is carried out in a special room in which the following equipment should be present:

  • special instruments required for cardiac catheterization;
  • catheters-electrodes;
  • apparatus for determining the vital signs of the human body;
  • a device that records electrograms;
  • defibrillator and other devices to restore the heartbeat.

Before starting the operation, the doctor gives the patient a sedative (makes the person relaxed, calm) and performs local anesthesia. It is done in the puncture area, that is, the place where the puncture will be performed. After this, RFA is started.

1. For arterial access, either the right or left femoral artery is selected. The radial arteries can also be selected. The puncture area is treated with a special antiseptic solution, after which it is covered with a sterile cloth.

2. Then a guide needle is inserted into the vessel. Immediately after this, the doctor, using X-ray control, inserts a catheter-electrode into the artery. The catheter is inserted through a hemostatic tube, which delivers it directly to the heart.

3. After inserting the catheters, the doctor will place them in the chambers of the heart. Once this is completed, the catheters are connected to equipment that records the ECG signals. It is this process that allows us to establish the cause of the impulse, which is the source of the arrhythmia. If necessary, the doctor may perform special tests to induce the arrhythmia.

4. Ablation can be performed through the AV node or in any other part of the rhythm source. After the electrode impacts the heart tissues, they will begin to heat up and reach a temperature of 40˚C. Such heating provokes the appearance of a micro-scar and artificial AV block.

5. To maintain artificially created AV block, the doctor uses previously inserted electrodes.

6. To understand whether the procedure gives positive results or not, an ECG is performed again. If the results of the electrocardiological study reveal that the result is unsatisfactory, the doctor may implant a pacemaker. If the results are positive, the operation will be considered completed. In this case, the doctor removes catheters and electrodes from the patient.

7. A special hemostatic and antibacterial bandage is applied to the puncture site.

8. After completion of RFA, the patient must stay in bed for 24 hours. If the femoral artery was punctured during RFA, then he is prohibited from bending his legs.

The duration of this operation can range from one and a half to six hours. It all depends on the depth of the cause of the arrhythmia.

The patient is discharged 2-4 days after the end of the procedure.

Possible problems

However, not all patients are immune from complications. These include:

  • people who have problems with blood clotting;
  • people with diabetes;
  • aged people. People over seventy are most susceptible to complications.

Complications that can occur both immediately after the operation and after some time include:

  • The occurrence of bleeding at the site of puncture of the artery.
  • Damage to the vascular wall. It may be disrupted while advancing the guidewire or catheter.
  • Formation of blood clots that can spread through the arteries.
  • Narrowing of the lumen of the pulmonary veins.
  • Irregular heart rhythm, which leads to worsening arrhythmia. In this case, a pacemaker is implanted.
  • Disruption of normal kidney function.

Postoperative period

After the operation is completed, the patient is placed on bed rest. He is under constant medical supervision and monitoring of the condition of his body. In addition, the patient must undergo repeated ECG procedures at certain intervals. The first time electrocardiography is performed six hours after completion of ablation. Next in twelve hours, and the last one in a day.

Blood pressure and body temperature are also measured.

If such discomfort becomes painful or does not go away after thirty minutes, the patient should immediately tell the doctor about it.

The first few days a person may feel an irregular heartbeat. However, this problem goes away very quickly.

The patient can be discharged the next day after completion of RFA. There are cases when a person’s health condition allows him to leave the hospital within a couple of hours after the ablation. If there are no contraindications and the doctor allows the patient to be discharged immediately after the operation, then this person is not recommended to drive a car himself. It's best if someone takes him home.

Rehabilitation

The rehabilitation period after catheter ablation can range from two to three months. During recovery, the patient may be prescribed special antiarrhythmic drugs, such as Propanorm, Propafenone and others.

There are a number of rules, following which, the patient will be able to quickly recover and forget about the procedure forever. These include:

  1. Maintain a normal physical activity regimen. The patient should not overwork. But at the same time, you shouldn’t lie in bed all the time. It is necessary to find the optimal activity at which there will be no jumps in the heart rate.
  2. During the rehabilitation period, the patient should reduce salt intake to a minimum.
  3. It is worth eliminating the consumption of alcoholic beverages.
  4. Avoid coffee and all drinks that contain caffeine for two to three months.
  5. Follow a diet. In particular, this applies to fats of animal origin. Their consumption should be kept to a minimum. If possible, exclude it from the diet altogether.
  6. If you have a bad habit such as smoking, quit smoking.

If the doctor was qualified, the operation was carried out successfully, and after the patient followed all the rules, then it will not be necessary to perform it again. Moreover, in this case, the recovery period will be minimal and without any consequences.

Patients' opinions

It’s not worth judging by reviews on the Internet, if only because not everyone leaves it. People who have not encountered problems or had any unpleasant experiences rarely leave feedback. This is not a new procedure, so it does not cause a stir among the population. However, many years of experience of doctors allows us to prepare the patient for the procedure and recovery after it.

There are almost no negative reviews. Many people report unpleasant sensations in the chest, which occur both during the operation and after its completion. However, doctors have noticed that most patients do not feel anything at all.

Many patients who have undergone this procedure are completely free of the disease and have not encountered arrhythmia for many years.

Negative reviews mainly concern the cost of the procedure. This procedure is not cheap, since it requires the latest equipment and highly qualified specialists.

Doctors have noticed that almost all nervous patients face pain problems both during and after surgery. Therefore, a stress test is performed before the procedure.

Suspicious patients do not get enough sleep before surgery and constantly make up their own minds. Negative consequences, which act as a placebo. As a result, this greatly affects their health.

Diet after hemorrhoid surgery

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Abnormal development of the AV node as a cause of reciprocal tachycardia

Cardiological diseases - myocardial infarction, coronary disease - are known to everyone. They have a pronounced, characteristic clinical picture and pose certain threats to the health, even life, of the patient. AV nodal reciprocal tachycardia is not a frequently diagnosed pathology; its name sounds ominously incomprehensible. How dangerous is the disease, what risks does this diagnosis carry?

What does the definition of disease mean?

The reason for the appearance of paroxysmal, that is, unexpected, rapid, irregular heartbeat is in altered electrical pathways that form or conduct signals.

Definition of atrioventricular nodal reciprocal tachycardia (ICD code 147): a disease caused by the presence of an additional conduction pathway in the heart muscles electrical signals, going from the atria to the ventricles.

The passage of an impulse in the atrioventricular node should normally slow down, but this does not happen due to the fact that the node branches (bifurcates). Abnormal activity of electrically conductive channels is not associated with organic or anatomical changes in muscle structure. This pathology develops more often in females than in representatives of the stronger half of humanity.

Causes

Reciprocal tachycardia is a congenital disease. Its manifestations can only be provoked by certain factors. It is quite possible to live a long life with cardiac conduction of the type of reciprocal tachycardia. During the interictal period, heart rate does not deviate from normal values.

The etiology of the disease is not fully understood. The most likely cause of tachycardia is considered to be congenital abnormalities during intrauterine development. They arise due to genetic mutation processes in the formation of the electrical structures of the heart. To this day, it has not been possible to establish under the influence of which specific causative factor the aberrant bifurcation of the node occurs, which is located between the atria (atrio means “atrium” in Latin) and the ventricle (hence the name “ventricular”).

Pregnancy with nervous stress, neglect of doctor’s recommendations, non-compliance with a rational regimen, balanced nutrition is a risk factor for the development of a supraventricular or atrial node of pathological electrical activity in an unborn child.

Signs of the disease do not always appear. For the manifestation of symptoms, the action of provoking factors is necessary:

  • nervous, physical or psychological stress;
  • smoking;
  • alcoholism;
  • physical fatigue;
  • drinking coffee in large quantities;
  • the presence of energy stimulants in the diet.

An organism that has been subjected to stress or regularly undergoes the action of the above factors gradually depletes its internal reserves, begins to look for a means of compensation, and an additional, bifurcation pathway of normal sinus rhythm is activated. This is how an ectopic focus of electrical activity is formed, which leads to paroxysms.

Symptoms

Women suffer from this disease several times more often than men, so clinical manifestations may be associated with hormonal changes in the body.

Patients describe their subjective state with the following symptoms:

  • the appearance of a feeling of pressure and discomfort in the heart area;
  • the occurrence of heart pain of varying intensity;
  • vestibular disorders;
  • respiratory disorders;
  • clouding of consciousness, even to the point of fainting;
  • stopping an attack is possible with little physical activity or holding your breath.

A discomfort in the chest is manifested by fluttering, trembling of the heart. The pain does not have a characteristic color, its intensity is weakly expressed, which becomes a differential sign in the diagnosis of this disease.

The vestibular apparatus reacts by disorienting the body in space: patients are forced to take a sitting or lying position due to sudden dizziness. Sometimes a short-term, sudden fainting occurs with all the typical signs of the condition:

  • cold extremities;
  • cyanosis of the nasolabial triangle;
  • pallor skin;
  • cold, clammy sweat.

For successful treatment of junctional tachycardia, it is first necessary to accurately diagnose the disease and differentiate the specific type of pathological conduction.

Diagnostics

The patient must be carefully interviewed, collect a life history and find out the professional aspects of his activities. Information about relatives who suffered from a similar disease and had the same symptoms of cardiac disorders is extremely important. This information will allow doctors to concentrate their efforts in the right direction.

After a detailed interview, it is necessary to examine the patient. Particular attention should be paid to the color, condition of the skin, nail phalanges of the fingers. Shape, pallor of color, bluishness or lack thereof can tell the cardiologist a lot about the condition of cardio-vascular system. The doctor must listen to the lungs and record the presence of any wheezing during breathing. It is important to note heart murmurs; this will become a criterion in making a diagnosis.

The patient takes a blood test for clinical and biochemical parameters. Particular attention should be paid to the levels of potassium and calcium in plasma, the activity of liver and cardiac transaminases, and the amount of cholesterol.

An electrocardiographic study (ECG) will finally confirm or deny the diagnosis of avnodal reentrant tachycardia. There are several types of pathology, which are determined by the direction of electrical activity. The orthodromic type is more common than the antidromic type. The difference between them is that the first type of reentrant activation consists of sequential transmission of the signal from the ventricles to the atria, after which it returns to the ventricles through the atrioventricular node and the Hiss bundle. The antidromic type also uses the electrical structures of the heart to conduct, but is directed in the opposite direction. This type of tachycardia has more stable manifestations, occurs regularly, and is characterized by an unchanged ventricular complex of waves on the cardiogram

Echocardiography becomes a mandatory stage of diagnosis; it will help to detect organic or structural disorders of the valvular or septal formations of the heart. At the present stage, the most informative method used to identify rhythm disturbances is electrophysiological research. During the procedure, a diagnostic probe is inserted through the femoral vein directly into the heart cavity, which makes it possible to find pathology in the connections of electrical structures.

Treatment

First aid in the event of an attack consists of providing the patient with rest, free access to oxygen, and warming the extremities. If possible, you can give heart drops or nitroglycerin, be sure to call ambulance or transport the patient to the nearest medical facility.

Sinoatrial tachycardia is subject to both conservative and surgical treatment. After a thorough examination and diagnosis, the patient is prescribed antiarrhythmic drugs, which can be administered intravenously or given in tablet preparations. Only a qualified cardiologist can choose the right medicine, its dose and frequency of administration, taking into account the patient’s condition and the presence of concomitant diseases. Traditional methods Treatments with herbs that improve overall well-being are not prohibited.

A characteristic differential sign of this type of congenital tachycardia is that when the anterior abdominal wall is tensed or the breath is held as much as possible, the paroxysm stops.

Indications for surgery are the following factors: professional activity that involves provoking attacks, tolerance to antiarrhythmic therapy, inability to take medications (for example, very young age, pregnancy, individual intolerance), debilitating nature of the disease. During the operation, an additional electrical path is destroyed, which helps normalize the direction and strength of the signal.

Prognosis and prevention

The vast majority of cases of the disease proceed according to a favorable scenario. The only complication of the pathology if it persists can be heart failure. This development is possible if myocardial contractility decreases. The prognosis for life is completely favorable.

There is no specific prevention for this disease, since the pathology is congenital. A timely visit to a cardiologist if a disorder is suspected can help avoid problems of this kind. heart rate, sports, healthy eating. When identifying cases of atrioventricular paroxysmal tachycardia among close relatives, it is necessary to undergo a complete cardiographic examination for problems with electrical conduction in the heart muscle.

Pregnant women should carefully monitor their health, follow the instructions and recommendations of the specialist they are seeing, in order to prevent the development of heart pathology in the unborn child.

The P waves overlap the QRS complexes and are therefore not visible. The QRS complex is narrow, the ventricular contraction rate is 150-200 per minute.

This form of supraventricular tachycardia occurs mainly in young people suffering from vegetative-vascular dystonia. This form of heart rhythm disorder is quite rare in people with heart disease.

The most common form of supraventricular tachycardia is reciprocal AV nodal tachycardia; the focus that initiates and maintains tachycardia is located above the level of the ventricles, in particular in the AV node.

It is believed that in the AV node as a result of the so-called longitudinal dissociation, two pathways of excitation are formed: a slow-conducting, or alpha, pathway with a short refractory period and a fast-conducting, or beta, pathway with a long refractory period. This splitting allows the circular motion of the excitation wave, when the excitation spreads from one path (alpha path) to another (beta path) and makes a rapid circular motion.

When analyzing ECG Noteworthy are the narrow QRS complexes, quickly following each other. The ventricular contraction rate is usually 120-220 per minute.

Scheme explaining the pathogenesis of reciprocal tachycardia and AV nodal re-entry tachycardia:
a It is believed that there are 2 conduction pathways in the AV node: slow (alpha pathway) and fast (beta pathway). Normally, excitation propagates distally along the fast pathway (a).
When it reaches the alpha path, there is a mutual cancellation of the excitation spreading along these two paths.
b Atrial extrasystoles, especially very early ones, are extinguished in the fast pathway, while along the slow pathway the excitation is conducted to the ventricles, causing their contraction later.
But excitation can also spread retrogradely along the fast path, cause contraction of the atria and then spread antegradely again and cause contraction of the ventricles (RP phenomenon If this circle of re-entry of the excitation wave persists for some time, then reciprocal AV nodal tachycardia occurs.
c If atrial extrasystoles are rare, they may be blocked in the slow pathway. Excitation spreads along a fast path to the ventricles and causes them to contract.
However, excitation can also spread retrogradely along the slow conduction pathway and cause delayed excitation of the atria (RP>PR phenomenon).

P waves, although recorded, are negative and, due to the high frequency of contractions, are not visible or are not clearly visible. This is explained by the fact that P waves overlap the QRS complexes or are recorded immediately after these complexes. The QRS and ST-T complexes do not change at first. Only with aberrant ventricular conduction can the QRS complexes be widened, as with bundle branch block (BBB).

Accurately determine P wave boundaries sometimes it's difficult. Therefore, previously they simply spoke of “supraventricular tachycardia”, without distinguishing between atrial and AV nodal tachycardia.

It is noteworthy that this tachycardia often occurs in young people, especially girls, suddenly, without apparent reason or after physical activity and just as suddenly it stops. These features have important clinical significance. Reciprocal AV nodal tachycardia can also occur in people with heart disease. However, in most cases, the general condition of patients, despite the rapid contractions of the ventricles, remains relatively satisfactory, since blood pressure, as well as stroke and cardiac output, decrease slightly.

It is known that after an attack reciprocal AV nodal tachycardia There is often excessive urination due to the release of atrial natriuretic peptide.

Treatment of reciprocal AV nodal tachycardia often begin with a massage of the carotid sinus, ask the patient to strain (Valsalva maneuver), give him a drink cold water If necessary, verapamil, cardiac glycosides, beta-adrenergic receptor blockers or flecainide are administered intravenously, and if there is no effect from these measures, catheter ablation is considered. Differential diagnosis and treatment of tachycardia with normal ventricular complexes are presented in the figure below.


.
Vegetovascular leafing. The P wave in lead V1 is visible immediately after the QRS complex (typical or “slow-fast” shape: RP The ventricular contraction rate is 170 per minute).

Features of the ECG in reciprocal AV nodal tachycardia:
The P wave is usually not clearly differentiated
QRS complexes are narrow
Heart rate: usually ranges from 150-220 per minute
It usually occurs in people without cardiac pathology, less often - with
Treatment: vagal tests, verapamil

  • Attacks of rapid rhythmic heartbeat, a feeling of the heart “fluttering” in the chest at a very high frequency, accompanied by:
    • shortness of breath;
    • discomfort or pain in the heart of various types;
    • weakness, dizziness;
    • loss of consciousness and attacks of suffocation (rarely observed with extremely high heart rates).
  • The attack can stop with a deep breath and holding your breath, straining (tension of the abdominal muscles).

Causes

  • Paroxysmal AV nodal reciprocal tachycardia is a congenital anomaly (deviation from the norm) of the structure of the heart.
  • The reason for its occurrence is a mutation (change) of genes, and therefore, during the formation and formation of the heart in utero (in the womb), the atrioventricular node splits (bifurcates) (a section of the heart that slows down the conduction of electrical impulses from the atria to the ventricles). This creates the basis for the occurrence of tachycardia (rapid heartbeat).
  • Among the factors that provoke the occurrence of tachycardia are:
    • stress;
    • smoking;
    • physical activity;
    • drinking alcohol and coffee.

Diagnostics

  • Analysis of the medical history and complaints (when did the feeling of rapid heartbeat appear, whether there are dizziness, weakness, loss of consciousness, attacks of suffocation during an attack, what the patient associates with the occurrence of these symptoms).
  • Analysis of the life history (whether the patient’s profession is associated with increased attention (due to the risk of loss of consciousness during an attack)).
  • Analysis of family history (whether the patient’s immediate relatives have cardiovascular diseases).
  • Physical examination. The color of the skin, the appearance of the skin, hair, nails, the frequency of respiratory movements, the presence of wheezing in the lungs and heart murmurs are determined.
  • General blood and urine analysis.
  • Biochemical blood test - determine the level of total cholesterol (a fat-like substance, a building element of cells), “bad” cholesterol (cholesterol that promotes the formation of cholesterol plaques) and “good” cholesterol (prevents the formation of cholesterol plaques), blood sugar level, potassium level (an element necessary for cell activity).

These two studies are carried out to identify concomitant pathologies.

  • ECG (electrocardiography). There are no specific changes in the electrocardiogram at rest. The examination may reveal signs of concomitant heart diseases.
  • CHMEKG (24-hour Holter electrocardiogram monitoring). An electrocardiogram is recorded within 24-72 hours. It allows you to determine the presence of specific tachycardia (an attack of rapid heartbeat), its duration, and the conditions under which it stops.
  • EchoCG (echocardiography). Determine whether there are structural changes in the heart (valves, walls, septa).
  • Transesophageal electrophysiological study. During the procedure, a thin tube is inserted through the nose or mouth into the esophagus to the level of the heart. At the same time, the parameters of heart activity are visible more clearly than on a conventional electrocardiogram. By applying an electrical impulse, you can trigger a short episode of tachycardia and accurately determine its type and characteristics. This procedure allows you to accurately establish the diagnosis.
  • Electrophysiological study. A thin probe is passed through the femoral vein directly into the heart, allowing the electrical activity of the heart to be directly measured. It is the most informative method for diagnosing rhythm disturbances (any rhythm different from the normal one - the rhythm of a healthy person).

Treatment of paroxysmal AV nodal reciprocal tachycardia

There are two methods of treating paroxysmal AV nodal reentrant tachycardia: conservative And surgical.

Conservative method.

  • Prevention of attacks of tachycardia (rapid heartbeat). For the purpose of prevention, antiarrhythmic drugs are prescribed (drugs that prevent the development of rhythm disturbances (any rhythm other than the normal one - the rhythm of a healthy person). The choice of drug is determined by a cardiologist based on the patient’s condition and the presence of concomitant diseases.
  • Termination of an attack of tachycardia. For this purpose, intravenous administration of antiarrhythmic drugs is used.
Surgical method.
Indications for surgical treatment are:
  • frequent attacks of tachycardia and their poor tolerance;
  • persistence of tachycardia attacks when taking antiarrhythmic drugs;
  • a profession associated with a risk to life in case of loss of consciousness;
  • situations where long-term drug therapy is undesirable (young age, planned pregnancy).

Surgical treatment of paroxysmal AV nodal reentrant tachycardia involves radiofrequency ablation of one of the bifurcated pathways in the atrioventricular node (a section of the heart that slows the conduction of electrical impulses from the atria to the ventricles).

The essence of the procedure is that a conductor (thin tube) is brought to the heart through the femoral vessels. An impulse is sent along the conductor, destroying one of the paths.

Complications and consequences

In general, the disease has a favorable prognosis.

The only complication with a long course of the disease and frequent episodes of tachycardia (attacks of rapid heartbeat) is the development of heart failure (disorders associated with a decrease in the contractility of the heart).

Prevention of paroxysmal AV nodal reciprocal tachycardia

  • The disease is hereditary, so there is no specific prevention of paroxysmal AV nodal reciprocal tachycardia.
  • Relatives of a person who has been diagnosed with this disease need to undergo a set of examinations (electrocardiogram, 24-hour electrocardiogram monitoring, echocardiography, and, if necessary, electrophysiological study)) to exclude the development of the disease.

Atrioventricular nodal reentrant tachycardia (AVNRT) accounts for 85% of all supraventricular arrhythmias, provided atrial fibrillation is excluded. In the population of patients suffering from this arrhythmia (namely, tachycardia), the ratio between women and men is 3:2. AVNRT is common in all age groups. However, in most cases, pronounced clinical manifestations occur between the ages of 28 and 40 years.

Clinic

A patient with AVNRT usually has no signs of structural myocardial pathology. The disease (tachycardia) occurs in the form of attacks of frequent rhythmic heartbeat, which begins and stops suddenly. The duration of AVNRT paroxysm is from several seconds to several hours, and the frequency of their occurrence is from daily attacks of arrhythmia to 1-2 times a year. Symptoms during an attack depend on the heart rate (usually from 140 to 250 per minute), the functionality of the cardiovascular system, and the presence of concomitant pathology. During paroxysm, patients usually complain of weakness, dizziness, and a feeling of pulsation in the vessels of the neck and head. Sometimes the attack is accompanied by the development of syncope and hypotension.

Pathogenesis

The pathogenesis is based on the functional division of the atrioventricular connection into 2 channels with different electrophysiological properties: “fast” and “slow”. These channels form 2 anterograde atrial entrances to the compact part of the atrioventricular junction in the region of Koch's triangle (an anatomical site located in the interatrial septum in the right atrium and bounded by the ligament of Todaro, the superior edge of the coronary sinus ostium and the fibrous ring of the tricuspid valve). At the same time, the “fast” part of the ABC is located in the upper parts of Koch’s triangle, has the properties of “fast” conduction (in sinus rhythm, conduction occurs precisely through it) and relatively high refractoriness values. At the same time, the fibers of the “slow” part are located in the lower parts of the triangle, passing from the upper edge of the coronary sinus, along the fibrous ring of the tricuspid valve to the compact part of the ABC. These fibers are characterized by slower conduction and low refractoriness values. The different electrophysiological properties of the two groups of fibers in this area are the basis for the formation of re-entry of excitation (re-entry) and the existence of tachycardia. With extraordinary contraction of the atria (for example, with an atrial extrasystole), a conduction block occurs in the fast part and the impulse is slowly conducted to the ventricles in the lower parts of Koch's triangle. During this time, excitability in the fast part has time to recover and the depolarization wave propagates retrogradely to the “fast” part, and then again to the “slow” part. Thus, re-entry is formed in the area of ​​the Koch triangle, which underlies AVNRT.

Classification

There are typical AVNRT and atypical forms of AVNRT. If during re-entry the excitation wave passes anterogradely along the slow part of the ABC, and retrogradely along the fast part, then we speak of a typical AVNRT (slow-fast). Among the atypical forms, fast-slow (circulation of the depolarization wave in the opposite direction) and slow-slow (retrograde impulse travels slowly) variants are distinguished. In this case, the fibers supporting the retrograde excitation front can be located in the middle parts of Koch's triangle.

Diagnostics

Registration of an ECG (mandatory in 12 leads) during an attack of tachycardia and against the background of sinus rhythm, with a high degree of probability, makes it possible to diagnose a typical AVNRT. In sinus rhythm, as a rule, no changes are detected on the ECG. During an attack of tachycardia, the R-R intervals are the same, the retrograde P-wave merges with the ventricular complex, sometimes a pseudo-r’ is formed, which is not recorded during sinus rhythm (especially in leads II, III, AVF, V1). In atypical AVNRT, a retrograde P wave is identified behind the ventricular complex (so-called long RP' interval tachycardia). In this case, an indirect sign indicating in favor of AVNRT will be the negative direction of the retrograde P wave in leads III, AVF. When a tachydependent blockade occurs along one of the His bundle branches, the length of the tachycardia cycle does not change. In addition, the differential diagnosis of AVNRT should be made with the entire spectrum of tachyarrhythmias with “narrow” and/or “wide” QRS complexes.

Transesophageal electrophysiological study allows non-invasive diagnosis of AVNRT. In addition to the above ECG characteristics, a typical form of AVNRT is characterized by: a sudden prolongation of the PQ interval during programmed atrial stimulation (the so-called “Jump” phenomenon or “jump”), which is explained by the relatively high value of the effective refractory period of the fast part of the AVS and the propagation of the impulse along the slow part; during tachycardia, the VA interval is less than 80 ms (from the beginning of the R wave in lead V1 to the A wave in the esophageal recording channel.

Conducting an endocardial electrophysiological study in modern cardiology is an absolute indication in patients with AVNRT. Signs of a typical AVNRT during endoEPI are:

  • the presence of the Jump phenomenon (more than 40 ms) of the A2-H2 interval during atrial programming (with the introduction of extrastimuli with a 10 ms prematurity step). This phenomenon may be present in 30% of healthy people or absent in patients with AVNRT in 30% of cases. Often, after a sudden prolongation of the A2-H2 interval, clinical tachycardia begins.
  • VA interval during tachycardia (from the beginning of the QRS complex in lead V1 to the beginning of atrial activation in the superolateral parts of the right atrium no more than 90 ms with a typical form of AVNRT)
  • so-called “central” type of retrograde atrial activation during an attack of tachycardia (i.e., the earliest retrograde atrial activation occurs in the area of ​​the electrodes recording His bundle activity)
  • absence of the phenomenon of “advancement” of the A’-A’ intervals during ventricular stimulation synchronized with the His bundle. This phenomenon indicates that retrograde conduction during tachycardia when a ventricular extrastimulus is applied occurs only along the His bundle and excludes conduction through additional atrioventricular conduction

Treatment

Paroxysm of AVNRT: An attack can be effectively stopped by performing reflex techniques (Valsalva maneuver, massage of the carotid sinuses). Among the pharmacological agents, the drugs of choice are verapamil, adenosine, obzidan, and novocainamide. Medicines can be prescribed either orally or parenterally. Transesophageal pacing may also be considered as a method of restoring sinus rhythm.

Long-term prophylactic use of antiarrhythmic drugs: Drugs can be prescribed for continuous use in patients with frequently recurrent attacks of tachycardia. The drugs of choice are quinidine, procainamide, disopyramide (in the absence of structural heart disease); verapamil; cordarone; sotalol; beta blockers. For rare, hemodynamically insignificant episodes of arrhythmia, on-demand therapy may be used. In this case, antiarrhythmic drugs are used orally only during an attack of tachycardia. The most commonly used are flecainide 200 mg or a combination of diltiazem 120 mg and anaprilin 80 mg.

Catheter ablation

Today, catheter ablation AVNRT is the most effective method of treating this arrhythmia, which allows the patient to completely stop taking antiarrhythmic drugs. The effectiveness of RFA AVNRT is 98-99%. Complications in the form of the development of high-degree AV block when modifying the slow part using RFA occurs in 1% (according to the leading electrophysiological laboratories in the world). It is based on the destruction of the fibers of the “slow” part in the lower part of Koch’s triangle. The criteria for effective RF exposure (a conventional catheter is used, power up to 50 W, temperature up to 60 degrees Celsius) are the appearance of an accelerated rhythm from the ABC during application, elimination of the “jump” phenomenon during programmed atrial stimulation, absence of AVNRT during stimulation in its modes induction. RFA AVNRT is an absolute indication in patients suffering from this arrhythmia. A contraindication to this operation is the patient’s preference for ongoing antiarrhythmic therapy.

At the Russian Clinical Center for Interventional Cardiology, GVKG named after. N.N. Burdenko from 1999 to 2005, about 200 RFA were performed for AVNRT. The effectiveness of the procedure after the first session was 97%, after the second - 100%. There were no complications associated with surgical treatment.

The main difficulty experienced by the doctor is when faced with an acutely developed paroxysm of tachycardia. Firstly, the urgency of the situation limits the time for making a decision and limits the possibilities of examining the patient for the most complete diagnosis - the decision often has to be made only on the basis of an objective examination of the patient and ECG data. Secondly, diagnosis is complicated by the absence of an ECG in dynamics, especially against the background of sinus rhythm - which is especially important when recording paroxysmal tachycardia with wide complexes. To facilitate the provision of care to patients with the occurrence of paroxysmal NRS, a diagnostic algorithm has been developed (3)

Paroxysmal tachycardias with narrow complexes- are always supraventricular (SVT). These include: sinus tachycardia - reciprocal and focal, atrial tachycardia; atrioventricular (AV) nodal reciprocal and focal tachycardia; orthodromic AV reciprocal tachycardia with WPW syndrome and hidden accessory AV junctions (AC), atrial fibrillation (AF) - atrial flutter and fibrillation. Differential diagnosis in this case concerns determining the exact location and mechanism of tachycardia.

Figure 12. Supraventricular tachycardia

With uneven R-R intervals, the most common cause of paroxysm is atrial fibrillation. The diagnosis becomes certain if f waves are recorded between the QRS complexes.

In the case of registration of regular tachycardia, a significant help in differential diagnosis is the shape and position of the P’ wave in relation to the QRS complex, if P’ can be seen on the ECG.

Figure 13. RP’>P’R (P’ in the second half of the cardiac cycle)

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In the case when the RP’ interval is longer than the P’R interval (P’ in the second half R-R cycle), the most likely diagnosis is atrial tachycardia(Figure 13). It is also possible reciprocal AV tachycardia involving slowly conducting accessory pathways, atypical AV nodal reciprocal tachycardia, or focal AV tachycardia– however, such situations are much less common. With atypical AV nodal reciprocal tachycardia, antegrade conduction in the circle occurs along fast pathways and retrograde through slow pathways. In this case, the negative P’ wave in leads III and AVF may be located in front of the QRS complex.

Figure 14. Sinus tachycardia

Atrial tachycardia (Figure 15). Possible mechanisms are abnormal automaticity, triggered activity, or micro re-entry within a single lesion in the atria. The exact mechanism of tachycardia is difficult to establish using conventional diagnostic methods. Heart rate ranges from 100 to 200 beats/min, a negative or biphasic P’ wave is recorded in the second half of the cardiac cycle, but closer to the middle (when AV conduction slows down, the P’ wave can be observed even in the first half). If the leading mechanism is abnormal automatism - paroxysm is characterized by the phenomenon of “warming up and cooling” of tachycardia - when the occurrence of tachycardia is accompanied by a gradual increase in its frequency, and the cessation of AT is preceded by a gradual slowdown of the atrial rhythm. Since the AV node (AVN) is not involved in the source of tachycardia, blockade of conduction along it does not interrupt the tachycardia - thus, registration of episodes of AV block that does not interrupt the paroxysm confirms the atrial nature of the tachycardia. This type of tachycardia often occurs in elderly patients with coronary artery disease.

Figure 15. Atrial tachycardia

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In the case when P' is recorded in the first half of the cardiac cycle - that is, P' follows the QRS complex, the atrio-ventricular node is most likely involved in the circulation of the re-entry wave. This may be AVU reciprocal tachycardia or AV reciprocal tachycardia with DS involvement. In the case of AVU reentrant tachycardia (AVNRT), the re-entry wave circulates inside the AVU. In AV reentrant tachycardia (AVRT), an additional AV connection is involved in the circulation of the re-entry wave. Thus, with AVNRT, the circulating wavelength is shorter, which is reflected in the ECG. With AVNRT, the P wave is close to the QRS complex or merges with it - as a rule, the interval between them does not exceed 0.07 seconds. With AVRT, the re-entry wave goes beyond the AVU and the path it must travel increases - therefore, the P wave moves away from the QRS by more than 0.07 sec, but remains in the first half of the cardiac cycle (Figure 16).

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AV nodal reentrant tachycardia (AVNRT) the most common variant of PSVT, is more often observed in women and is rarely combined with structural heart pathology (Figure 17). The very concept of reciprocal tachycardia implies that the pathogenesis of rhythm disturbance is based on the mechanism of circulation of the re-entry wave. With AVNRT, the circulation of the excitation wave occurs inside the AVN between two functionally and anatomically dissociated pathways (a- and b-paths).

In typical AVNRT, antegrade AV conduction occurs along the slow pathways and retrograde through the fast pathways. As a result, when recording an ECG, the P-wave merges with the QRS complex or is close to it (< 70 мс). В случаях, когда Р-волна не визуализируется, может быть полезным запись чреспищеводной электрокардиограммы.

Figure 17. Atrioventricular nodal tachycardia

If the P-wave is separated from the QRS by more than 70 ms (0.07 sec) - most likely we are dealing with AVRT (orthodromic option). In the orthodromic variant of reciprocal AV tachycardia, antegrade conduction is carried out through the AVU, and retrograde conduction is carried out through the DC (Figure 18). In this case, antegrade conduction occurs through the AVU, and the return of the re-entry wave occurs through the DS. In this case, excitation is carried out to the ventricles physiologically and the QRS complexes remain narrow. The re-entry wave circulates in a larger circle than with AVNRT, so the P wave is spaced from the QRS complex by more than 0.07 seconds (Figure 19). At the same time, when recording such an ECG, one should remember the possibility of atrial tachycardia with functional slowing of AV conduction (as mentioned above).

Figure 18. Scheme of the movement of the re-entry wave during orthodromic AVRT.

Paroxysmal AV nodal reciprocal tachycardia of an unusual type (ventricular extrastimulus)

According to the work we cited by V. Strasberg et al. (1981) the retrograde ERP of the fast channel averaged 445 ± 94 ms with fluctuations from 290 to 620 ms. The retrograde ERP of the slow channel averaged 349 ± 115 ms with fluctuations from 210 to 550 ms. With this refractoriness ratio, premature ventricular extrastimulus can be blocked at the entrance to the fast channel and spread upward along the slow retrograde nodal channel.

Re-entry becomes possible at the moment of “critical” slowdown of VA conduction through this channel. With increasing frequency of ventricular stimulation in patients, a gradual lengthening of the V-A interval occurs in the form of the Wenckebach period, which confirms the fact of retrograde VA nodal conduction. This is also indicated by the fact that activation of the His bundle (potential H) precedes activation of the atrium (A).

The same ratio is observed during ventricular extrastimulation (H 3 is ahead of A.%). V. Strasberg et al. (1981) caused single echo complexes of an unusual type (f/s) in all patients who had two retrograde canals in the AV node. However, they were able to cause unusual AV nodal reentrant tachycardia only in 4 out of 31 patients (about 13%). In the remaining patients, the slow channel was not capable of conducting more than one impulse in the retrograde direction.

According to the ideas of P. Brugada et al. (1981), AV tachycardia of an unusual type is not induced by atrial extrastimuli, does not occur spontaneously without ventricular extrasystole with a “critical” coupling interval. Intravenous administration of atropine sulfate does not seem to increase the likelihood of reproducing this tachycardia.

Recently, V. Lerman et al. (1987) managed to induce such tachycardia in 5 patients using both ventricular and atrial programmed electrical stimulation. In this regard, it is also interesting that out of 31 patients examined by V. Strasberg et al. in 11 (35.5%) in the AV node, in addition to two retrograde canals, two anterograde canals were found.

The same sequence of retrograde excitation of the atria in the usual and unusual types of AV nodal re-entry indicated that in fact these patients had only two nodal channels capable of conducting impulses in the retrograde and anterograde directions. It is easy to imagine that, under favorable circumstances, some of these patients could develop attacks of both ordinary and unusual AV nodal reciprocal PT.

“Arrhythmias of the heart”, M.S. Kushakovsky

Paroxysmal AV nodal reentrant tachycardia of unusual type

Emergency care for paroxysmal reciprocal AV tachycardias

The most common forms of supraventricular paroxysmal tachycardia; for many decades they were mistakenly attributed to atrial “classical” tachycardia. It has now been proven that the basis of such tachycardias is the circular movement of the impulse in the area of ​​the AV junction. Several variants of paroxysmal reciprocal AV tachycardia can be distinguished.

AV nodal reciprocal tachycardia, AV reciprocal tachycardia in individuals with WPW syndrome, AV reciprocal tachycardia in individuals with hidden accessory pathways that conduct impulses only in the retrograde direction from the ventricles to the atria, AV reciprocal tachycardia in individuals with LGL syndrome.

All these options have a number of common features:

  1. sudden onset of an attack after one or several extrasystoles (usually atrial with prolongation of the P-R interval);
  2. correctness (regularity) of the tachycardic rhythm without a “warm-up” period;
  3. narrow supraventricular-looking QRS complexes;
  4. stability of AV conduction 1:1 and cessation of the attack when blockade develops in any link of the re-entry loop, in particular in the AV node or in the accessory pathway;
  5. acute end of an attack, which may be followed by a post-tachycardic pause.

Patients suffering from attacks of AV nodal reciprocal tachycardia are older in age than persons with other forms of AV reciprocal tachycardia; In half of them, organic changes are found in the heart.

To stop attacks of this tachycardia, patients themselves resort to vagal techniques. Over time, their effect decreases. This circumstance, as well as the fact that when the attack is prolonged, circulatory disorders may occur, forces patients to seek treatment. medical assistance. The drug of choice is verapamil (isoptin). Isoptin quickly (sometimes “on the needle”) eliminates attacks in 85 - 90% of patients. First, 2 ml of 0.25% isoptin solution (5 mg) is injected into a vein over 2 minutes, if necessary, another 5 mg every 5 minutes to a total dose of 15 mg. In more stable cases, isoptin injections can be combined with vagal techniques.

However, in 10-15% of patients it is not possible to achieve an effect. In such a situation (no earlier than 15 minutes after isoptin), it is better to try the effect of novocainamide: 10 ml of a 10% solution of novocainamide is injected into a vein slowly along with 0.3 ml of a 1% solution of mesatone. The latter not only counteracts the decrease in blood pressure, but through the baroreceptor reflex stimulates vagal anterograde inhibition of the AV node. It seems preferable to administer procainamide slowly according to the method described above - no more than 50 mg over 1 minute. In some cases, electrical cardioversion is used. After successful elimination of the attack, in the absence of complications, patients can remain at home.

The first attacks of tachycardia in patients with WPW syndrome often begin in childhood or adolescence. In many of them, in addition to attacks of tachycardia and signs of WPW syndrome, it is not possible to identify any other changes in the heart.

When treating these paroxysms of tachycardia, one proceeds in a well-known manner:

  1. vagal techniques (massage of the sinocarotid region);
  2. intravenous administration of 10 mg isoptin, which may be effective;
  3. intravenous administration of 5-10 ml of 10% solution of novocainamide;
  4. electrical cardioversion. If a high-frequency paroxysm can be eliminated with a single electrical discharge, then this may serve as an additional indication that the impulse propagated along a long loop (additional extra-nodal path).

A form of AV reciprocal tachycardia is often encountered, associated with the functioning of hidden retrograde ventricular-atrial accessory pathways. In such patients, mostly young people without organic changes in the heart, there are no signs of WPW syndrome on the ECG. Treatment of attacks of this tachycardia is carried out in the same way as other attacks of AV reciprocal tachycardia. After intravenous administration of isoptin, one can see, immediately before the end of the attack, an alternation of long and short R-R intervals.

The latter form of AV reciprocal tachycardia is observed in individuals with ECG signs of LGL syndrome. Paroxysms of this tachycardia are suppressed using the therapeutic measures described above. Hospitalization of patients is carried out only in the presence of complications.

Ed. V. Mikhailovich

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