Holter monitoring AV block 2nd degree, type 2. Cardiac conduction disorders (AV block)

a common part

Atrioventricular, or atrioventricular, blockade (AV block)- This different kinds disturbances in the conduction of impulses from the atria to the ventricles.

To the most common reasons This disorder includes idiopathic fibrosis and sclerosis of the conduction system.

The diagnosis is made on the basis of an ECG.

Clinical manifestations and treatment depend on the severity of the block, but treatment usually includes pacing.

• Classification of AV blocks
  • ECG classification of AV blocks

    Classification of AV blocks based on ECG data reflects the severity and level of impulse conduction disturbance.

    • Degrees of AV block
      • AV block of the first degree.

        All atrial impulses reach the ventricles, but conduction through the AV node occurs with the same delay.

      • AV block of the second degree.

        Individual atrial impulses are not conducted to the ventricles. There are 3 types of 2nd degree AV block:

        • Mobitz type I (Wenckebach block).
        • Type Mobitz II.
        • Incomplete high degree AV block.
        • Some authors identify a fourth variant of second-degree AV block - a 2:1 block.
      • AV block III degree(complete AV block).

        Impulses from the atria do not reach the ventricles. There is complete separation of atrial and ventricular rhythms.

      Any blockade can be persistent, transient (transitory) and intermittent.

    • Classification of AV blockades by localization of impulse conduction disturbances

      Based on the localization of impulse conduction disturbances, AV blockades are classified into proximal and distal.

      There are combined blockades (at different levels).

  • Classification of AV blocks by prognostic value
    • Relatively favorable AV blocks (not prone to progression):
      • First degree AV block, especially proxial and not associated with posteroinferior myocardial infarction.
      • Chronic or functional (vagal) AV block of the second degree, type I.
    • Favorable AV block:
      • Acute development Second degree AV block of the 1st and especially the 2nd type (especially with wide QRS complexes, which indicates a distal level of blockade).
      • Acute and most variants of chronic complete AV block, which is often distal.

• Epidemiology of AV blocks

  The incidence of this pathology increases with age. The prevalence of third degree AV block reaches its maximum values ​​in people over 70 years of age with concomitant diseases hearts.

  AV block is most often observed among patients with heart disease. Approximately 5% of patients with heart disease have first-degree AV block and 2% of patients have second-degree AV block.

  Congenital AV block of the third degree is quite rare (approximately 1 case per 20 thousand newborns).

  Atrioventricular block of the second degree, mainly type I, occurs in isolated healthy individuals young. It usually occurs during sleep, disappearing with physical activity, which indicates its connection with increased tone vagus nerve and is considered a variant of the norm.

• ICD-10 code

  Etiology and pathogenesis

  • Etiology of atrioventricular blocks

    Atrioventricular block can develop when various diseases(How of cardio-vascular system and non-cardiac), and also be a consequence of taking medications.

    Reasons for the development of AV block:

    • IHD.
    • Myocarditis.

      The acute development of transverse heart block may be the only symptom of myocarditis and requires careful examination.

      AV blockade can complicate the course of myocarditis.

      In many cases, conduction disturbances in myocarditis are reversible and disappear as the process subsides.

      AV blockade is more often observed in the following myocarditis:

      Specific myocarditis (with diphtheria, Lyme disease and Reiter's syndrome, Chagas disease, measles, mumps.

      Thyrotoxic myocarditis.

      Autoimmune myocarditis - against the background of rheumatism, infective endocarditis, systemic lupus erythematosus.

    • Postmyocardial cardiosclerosis.

      Postmyocardial cardiosclerosis can lead to the development of persistent conduction disorders.

      The most specific in relation to the inflammation suffered is the combined damage to different parts of the conduction system.

      It is characterized by a combination with tachyarrhythmias caused by the presence of zones of fibrosis in the myocardium and conduction system, which become part of the re-entry loop circuit.

    • Non-ischemic degenerative and infiltrative diseases with damage to the conduction system of the heart.

      There are a number of diseases that are characterized by damage to the conduction system of the heart:

      Amyloidosis. Senile amyloidosis clinically manifests itself after 75 years of age. Developing clinical picture heart damage, which is difficult to distinguish from ischemic heart disease. However, earlier lesions are also possible within the framework of hereditary amyloidosis, and less commonly, secondary amyloidosis.

      Clinic and complications

      • Clinic for atrioventricular block

        Peculiarities clinical course and prognosis for AV blockade are determined primarily by the level of blockade and, to a lesser extent, by the degree of blockade.

        Distal blockades are generally more severe than proximal ones. This is associated with a lower frequency and stability of the idioventricular rhythm, a greater susceptibility to Morgagni–Adams–Stokes attacks and the development of heart failure.

        The course of the disease also depends on the etiology of AV block and the severity of concomitant cardiac damage.

        Blockades at the level of the AV node that do not lead to the development of bradycardia do not manifest themselves clinically.

        Complaints are usually made only by patients with acquired high-degree atrioventricular blockade, accompanied by noticeable bradycardia.

        Due to the impossibility of an adequate increase in heart rate (and, as a consequence, cardiac output), during physical activity such patients experience weakness and shortness of breath, and less often, attacks of angina.

        Decreased cerebral perfusion is manifested by syncope and transient feelings of confusion.

        Occasionally, with second degree atrioventricular block, patients may experience prolapses as interruptions.

        Fainting episodes associated with a decrease in heart rate (Morgagni-Adams-Stokes attacks) are especially characteristic of the development of third-degree AV block, when a long pause may occur due to a delay in the activity of the replacement pacemaker.

        Congenital complete AV block in childhood and adolescence, and in most patients in adulthood, is asymptomatic.

        Distal blockades can develop against the background of symptoms acute heart attack myocardium.

      • Complications of atrioventricular blockade

        Complications of atrioventricular block occur in a significant proportion of patients with acquired high-degree atrioventricular block and complete AV block.

        Complications of atrioventricular blockade are caused mainly by a significant slowdown in the ventricular rhythm against the background of severe organic disease hearts.

        Main complications of AV block:

        • Morgagni-Adams-Stokes attacks.

          The most common complications include Morgagni-Adams-Stokes attacks and the onset or worsening of chronic heart failure and ectopic ventricular arrhythmias, including ventricular tachycardia.

          A Morgagni-Adams-Stokes attack usually develops at the moment of transition of incomplete atrioventricular blockade to complete, before the start of stable functioning of the pacemaker II - III order, or with persistent third-degree AV block, often distal, with a sudden decrease in the frequency of the impulses generated by it.

          Analysis of the ECG in a lead in which the P waves are clearly visible allows us to detect during pauses the loss of only the QRST complex, which is characteristic of second degree atrioventricular block, or simultaneously this complex and the P wave, characteristic of second degree sinoatrial block.

          Availability on ECG waves P, following regardless of the QRST complexes with a higher frequency, distinguishes complete AV block from an escape rhythm from the atrioventricular junction or idioventricular when the sinus node stops.

          In favor of blocked atrial or nodal extrasystoles, in contrast to second degree AV block, is evidenced by the absence of a pattern of loss of the QRST complex, the shortening of the P-P interval before the loss compared to the previous one, and the change in the shape of the P wave, after which the ventricular complex falls out, compared to preceding P waves sinus rhythm. The last sign cannot always be identified - in doubtful cases, the diagnosis can be clarified only by recording an intracardiac ECG during an electrophysiological study of the heart.

          Atrioventricular dissociation is characterized by the presence of independent pacemakers of the atria and ventricles in the absence of retrograde conduction of ventricular impulses. It can occur in combination with AV block or in the absence of the latter. Required condition development of atrioventricular dissociation and the main criterion for its diagnosis is a high frequency of the ventricular rhythm compared to the frequency of atrial excitation caused by a sinus or ectopic atrial pacemaker. Often this difference is quite small.

          Important To assess the prognosis and select the optimal treatment tactics, it is necessary to determine the level of atrioventricular blockade, especially complete blockade. In the differential diagnosis of proximal and distal AV block of the third degree, the first is indicated by a heart rate at rest of more than 45 beats per minute, mild fluctuations in the duration of the R - R intervals and the possibility of an increase in heart rate during physical activity, during inspiration and after the administration of atropine sulfate.

          The differential diagnostic value of the width and graphics of the QRS complexes is very limited.

          Carrying out simple electrocardiographic tests helps to clarify the localization of atrioventricular blockade of the II - III degree. Slowing down atrioventricular conduction by vagus nerve stimulation, such as with carotid sinus massage, aggravates proximal atrioventricular block, while the degree of distal blockade in response to a decrease in the number of impulses passing through the atrioventricular node, on the contrary, decreases. In contrast, physical activity and the administration of atropine sulfate have a positive effect on the conduction coefficient with AV block localized at the level of the atrioventricular node and a negative effect with blockade of distal localization.

          Most precise method assessment of the level of atrioventricular blockade is the registration of an intracardiac ECG during an electrophysiological study of the heart, which is resorted to in unclear and controversial cases.

RCHR (Republican Center for Health Development of the Ministry of Health of the Republic of Kazakhstan)
Version: Clinical protocols of the Ministry of Health of the Republic of Kazakhstan - 2014

Bifascicular block (I45.2), Other and unspecified atrioventricular block (I44.3), Second degree atrioventricular block (I44.1), First degree atrioventricular block (I44.0), Complete atrioventricular block (I44.2), Sick sinus syndrome (I49.5), Trifascicular block (I45.3)

Cardiology

general information

Short description

Approved
at the Expert Commission on Healthcare Development
Ministry of Health of the Republic of Kazakhstan
Protocol No. 10 dated July 04, 2014

AV block represents a slowdown or cessation of impulses from the atria to the ventricles. For the development of AV block, the level of damage to the conduction system may vary. This may be a conduction disorder in the atria, AV junction, and ventricles.

I. INTRODUCTORY PART

Protocol name: Cardiac conduction disorders

Protocol code

ICD-10 codes:
I44.0 First degree atrioventricular block
I44.1 Second degree atrioventricular block
I44.2 Complete atrioventricular block
I44.3 Other and unspecified atrioventricular block
I45.2 Double bundle block
I45.2 Trifascicular block
I49.5 Sick sinus syndrome

Abbreviations used in the protocol:
HRS - Heart Rhythm Society
NYHA - New York Heart Association
AV block - atrioventricular block
blood pressure - arterial pressure
ACE - angiotensin-converting enzyme
VVFSU - sinus node function recovery time
HIV - human immunodeficiency virus
VSAP - sinoauricular conduction time
ACE inhibitors - angiotensin-converting enzyme inhibitors
IHD - ischemic disease hearts
HV interval - impulse conduction time according to the His-Purkinje system
ELISA - linked immunosorbent assay
LV - left ventricle
MPCS - maximum duration of the stimulation cycle
SVC - sinus cycle duration
PCS - duration of the stimulation cycle
SA block - sinoatrial block
HF - heart failure
SNA - sinoatrial node
FGDS - fibrogastroduodenoscopy
HR - heart rate
ECG - electrocardiogram
EX - pacemaker
ERP - effective refractory period
EPI - electrophysiological study
EchoCG - echocardiography
EEG - electroencephalography

Date of development of the protocol: year 2014

Protocol users: interventional arrhythmologists, cardiologists, therapists, doctors general practice, cardiac surgeons, pediatricians, emergency doctors, paramedics.

Classification

Classification of AV block by degree:

First degree AV block is characterized by a slowdown in the conduction of impulses from the atria to the ventricles. The ECG shows a prolongation P-Q interval more than 0.18-0.2 sec.

. With second degree AV block, single impulses from the atria sometimes do not pass into the ventricles. If this phenomenon occurs rarely and only one ventricular complex is lost, patients may not feel anything, but sometimes they feel moments of cardiac arrest, during which dizziness or darkening occurs in the eyes.

AV block of the second degree, type Mobitz I - the ECG shows a periodic prolongation of the P-Q interval followed by a single P wave, which does not have a subsequent ventricular complex (type I block with Wenckebach periodicity). Typically, this variant of AV block occurs at the level of the AV junction.

AV block of the second degree, type Mobitz II, is manifested by periodic loss of QRS complexes without a previous prolongation of the PQ interval. The block level is usually the His-Purkinje system, the QRS complexes are wide.

. Third degree AV block (complete atrioventricular block, complete transverse block) occurs when electrical impulses from the atria are not conducted to the ventricles. In this case, the atria contract at a normal rate, and the ventricles contract rarely. The frequency of ventricular contractions depends on the level at which the center of automaticity is located.

Sick sinus syndrome
SSS is a dysfunction of the sinus node, manifested by bradycardia and accompanying arrhythmias.
Sinus bradycardia- decrease in heart rate less than 20% below the age limit, migration of the pacemaker.
SA block is a slowdown (below 40 beats per minute) or cessation of impulse transmission from the sinus node through the sinoatrial junction.

Classification of SA block by degree :

The first degree of SA block does not cause any changes in cardiac activity and does not appear on a regular ECG. With this type of blockade, all sinus impulses pass to the atria.

With second-degree SA block, sinus impulses sometimes do not pass through the SA junction. This is accompanied by loss of one or more atrioventricular complexes in a row. With a second degree block, dizziness, a feeling of irregular heart activity, or fainting may occur. During pauses of SA blockade, escape contractions or rhythms may appear from underlying sources (AV junction, Purkinje fibers).

With third-degree SA block, impulses from the SPU do not pass through the SA junction and cardiac activity will be associated with the activation of the following rhythm sources.

Tachycardia-bradycardia syndrome- combination of sinus bradycardia with supraventricular heterotopic tachycardia.

Sinus arrest is a sudden cessation of cardiac activity with the absence of contractions of the atria and ventricles due to the fact that the sinus node cannot generate an impulse for their contraction.

Chronotropic insufficiency(incompetence) - inadequate increase in heart rate in response to physical activity.

Clinical classification AV blocks

According to the degree of AV block:
. 1st degree AV block

AV block II degree
- Mobitz type I

Type Mobitz II
- AV block 2:1
- High degree AV block - 3:1, 4:1

AV block III degree

Fascicular block
- Bifascicular blockade
- Trifascicular block

By time of occurrence:
. Congenital AV block
. Acquired AV block

According to the stability of AV block:
. Permanent AV block
. Transient AV block

Sinus node dysfunction:
. Sinus bradycardia
. Sinus arrest
. SA blockade
. Tachycardia-bradycardia syndrome
. Chronotropic insufficiency

Diagnostics

II. METHODS, APPROACHES AND PROCEDURES FOR DIAGNOSIS AND TREATMENT

List of basic and additional diagnostic measures

Basic (required) diagnostic examinations carried out on an outpatient basis:
. ECG;
. Holterovskoe ECG monitoring;
. Echocardiography.

Additional diagnostic examinations performed on an outpatient basis:
If organic cerebral pathology is suspected or in case of syncope of unknown origin:

X-ray of the skull and cervical spine spine;

. EEG;
. 12/24-hour EEG (if epileptic genesis of paroxysms is suspected);


. Doppler ultrasound(if pathology of extra- and intracranial vessels is suspected);

General blood test (6 parameters)

General urine analysis;


. coagulogram;
. HIV ELISA;



. FGDS;

The minimum list of examinations that must be carried out when referring to planned hospitalization :
. general analysis blood (6 parameters);
. general urine analysis;
. microprecipitation reaction with antilipid antigen;
. biochemical analysis blood (AlAT, AST, total protein, bilirubin, creatinine, urea, glucose);
. coagulogram;
. HIV ELISA;
. ELISA for markers viral hepatitis B, C;
. blood type, Rh factor;
. plain radiography organs chest;
. FGDS;
. additional consultations specialized specialists if available concomitant pathology(endocrinologist, pulmonologist);
. consultation with a dentist or otolaryngologist to exclude foci of chronic infection.

Basic (mandatory) diagnostic examinations carried out on stationary level:
. ECG;
. Holter ECG monitoring;
. Echocardiography.

Additional diagnostic examinations carried out at the hospital level:
. massage carotid sinus;
. sample with physical activity;
. pharmacological tests with isoproterenol, propronolol, atropine;
. EPI (performed in patients with clinical symptoms in whom the cause of symptoms is unclear; in patients with asymptomatic His bundle branch block, if pharmacotherapy is planned that can cause AV block);

If organic cerebral pathology is suspected or in case of syncope of unknown origin:
. radiography of the skull and cervical spine;
. examination of the fundus and visual fields;
. EEG;
. 12/24 - hourly EEG (if epileptic genesis of paroxysms is suspected);
. echoencephaloscopy (if there is a suspicion of volumetric processes in the brain and intracranial hypertension);
. CT scan(if there is a suspicion of space-occupying brain processes and intracranial hypertension);
. Doppler ultrasound (if pathology of extra- and intracranial vessels is suspected);

Diagnostic measures carried out at the emergency stage emergency care :
. blood pressure measurement;
. ECG.

Diagnostic criteria

Complaints and anamnesis- main symptoms
. Loss of consciousness
. Dizziness
. Headache
. General weakness
. Determine the presence of diseases predisposing to the development of AV block

Physical examination
. Pallor skin
. Sweating
. Rare pulse
. Auscultation - bradycardia, first heart sound of varying intensity, systolic murmur above the sternum or between the apex of the heart and the left edge of the sternum
. Hypotension

Laboratory tests: not carried out.

Instrumental studies
ECG and daily monitoring ECG (main criteria):

With AV block:
. Rhythm pauses of more than 2.5 seconds (R-R interval)
. Signs of AV dissociation (lack of conduction of all P waves to the ventricles, which leads to complete dissociation between P waves and QRS complexes)

With SSSU:
. Rhythm pauses of more than 2.5 seconds ( P-P interval)
. Increase in the R-R interval by 2 or more times from normal interval R-R
. Sinus bradycardia
. No increase in heart rate during emotional/physical stress (chronotropic insufficiency of the heart rate)

EchoCG:
. Hypokinesis, akinesis, dyskinesis of the walls of the left ventricle
. Changes in the anatomy of the walls and cavities of the heart, their relationship, the structure of the valve apparatus, systolic and diastolic function of the left ventricle

EFI ( additional criteria):

. With SSSU:

	Test	Normal answer	Pathological response
1	VVFSU	<1,3 ПСЦ+101мс	>1.3 PSC+101ms
2	Corrected VVFSU	<550мс	>550ms
3	MPCS	<600мс	>600ms
4	VSAP (indirect method)	60-125ms	>125ms
5	Direct method	87+12ms	135+30ms
6	Electrogram SU	75-99ms	105-165ms
7	ERP SPU	325+39ms (PCS 600ms)	522+39ms (PCS 600ms)

With AV block:

Prolongation of the HV interval more than 100 ms

Indications for consultation with specialists (if necessary, according to the decision of the attending physician):

Dentist - sanitation of foci of infection

Otolaryngologist - to exclude foci of infection

Gynecologist - to exclude pregnancy, foci of infection

Differential diagnosis

Differential diagnosis cardiac conduction disorders: SA and AV blockade

Differential diagnosis with AV blockade
SA blockade	Analysis of the ECG in a lead in which the P waves are clearly visible allows us to detect during pauses the loss of only the QRS complex, which is typical for AV block of the second degree, or simultaneously this complex and the P wave, characteristic of SA block of the 2nd degree
Escaping rhythm from the AV junction	The presence of P waves on the ECG, which follow independently of the QRS complexes with a higher frequency, distinguishes complete AV block from an escape rhythm from the atrioventricular junction or idioventricular when the sinus node stops
Blocked atrial extrasystole	In favor of blocked atrial or nodal extrasystoles, in contrast to second-degree AV block, is evidenced by the absence of a pattern of loss of the QRS complex, the shortening of the P-P interval before the loss compared to the previous one, and the change in the shape of the P wave, after which the ventricular complex falls out, compared to preceding P waves of sinus rhythm
Atrioventricular dissociation	A prerequisite for the development of atrioventricular dissociation and the main criterion for its diagnosis is a high frequency of the ventricular rhythm compared to the frequency of atrial excitation caused by a sinus or ectopic atrial pacemaker.

Differential diagnosis for SSSU
	Test	Normal answer	Pathological response
1	Carotid sinus massage	Decreased sinus rhythm (pause< 2.5сек)	Sinus pause>2.5 sec
2	Exercise test	Sinus rhythm ≥130 at stage 1 of the Bruce protocol	There are no changes in sinus rhythm or the pause is insignificant
3	Pharmacological tests
A	Atropine (0.04 mg/kg, i.v.)	Increased sinus rate ≥50% or >90 beats/min	Increased sinus rhythm<50% или<90 в 1 минуту
b	Propranolol (0.05-0.1 mg/kg)	Decreased sinus rhythm<20%	The decrease in sinus rhythm is more significant
V	Own heart rate (118.1-0.57* age)	Own heart rate within 15% of calculated	<15% от расчетного

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Treatment

Treatment goals:

Improving life prognosis (preventing sudden cardiac death, increasing life expectancy);

Improving the patient's quality of life.

Treatment tactics

Non-drug treatment:

Bed rest;

Diet No. 10.

Drug treatment

with acute development of AV block, SSSU before pacemaker installation(mandatory, 100% probability)

Drug treatment provided on an outpatient basis before hospitalization:

List of essential medicines(having a 100% probability of application).

List of additional medicines(less than 100% chance of application)

№	Additional	Quantity per day	Duration of use	Likelihood of application
1	0.5% dopamine solution 5 ml	1-2	1-2	50%
2		1	1-2	50%
3	1% phenylephrine solution 1 ml	1-2	1-2	50%

Drug treatment provided at the inpatient level

List of essential medicines(having a 100% probability of application)

List of additional medicines c (less than 100% probability of application).

№	Additional	Quantity per day	Duration of use	Likelihood of application
1	0.5% dopamine solution 5 ml	1-2	1-2	50%
2	0.18% epinephrine solution 1 ml	1	1-2	50%
3	1% phenylephrine solution 1 ml	1-2	1-2	50%

Drug treatment provided at the emergency stage

№	Basic	Quantity per day	Duration of use	Likelihood of application
1	0.1% atropine sulfate solution 1 ml	1-2	1-2	100%
2	0.18% epinephrine solution 1 ml	1	1-2	50%
3	1% phenylephrine solution 1 ml	1-2	1-2	50%

Other treatments:(at all levels of medical care)

For hemodynamically significant bradycardia:

Place the patient with the lower limbs elevated at an angle of 20° (if there is no pronounced congestion in the lungs);

Oxygen therapy;

If necessary (depending on the patient’s condition), closed heart massage or rhythmic tapping on the sternum (“fist rhythm”);

It is necessary to discontinue drugs that could cause or worsen AV block (beta-blockers, slow calcium channel blockers, antiarrhythmic drugs of classes I and III, digoxin).

These measures are carried out until the patient’s hemodynamics are stabilized.

Surgical intervention

Electrocardiostimulation- the main method of treating cardiac conduction disorders. Bradyarrhythmias account for 20-30% of all heart rhythm disorders. Critical bradycardia threatens the development of asystole and is a risk factor for sudden death. Severe bradycardia worsens the quality of life of patients, leading to dizziness and syncope. Elimination and prevention of bradyarrhythmias will solve the problem of threat to life and disability of patients. ECS are implantable automatic devices designed to prevent bradycardic episodes. The electrical stimulation system includes the device itself and electrodes. According to the number of electrodes used, pacemakers are divided into single-chamber and double-chamber.

Surgical intervention provided on an outpatient basis: no.

Surgical intervention provided in a hospital setting

Indications for permanent pacing in AV block

Class I

Third degree AV block and progressive second degree AV block of any anatomical level associated with symptomatic bradycardia (including heart failure) and ventricular arrhythmias due to AV block (Level of Evidence: C)

Third degree AV block and progressive second degree AV block of any anatomical level associated with arrhythmias and other medical conditions requiring medical treatment causing symptomatic bradycardia (Level of Evidence: C)

Third degree AV block and progressive second degree AV block at any anatomical level with documented periods of asystole greater than or equal to 2.5 seconds, or any escape rhythm<40 ударов в минуту, либо выскальзывающий ритм ниже уровня АВ узла в бодрствующем состоянии у бессимптомных пациентов с синусовым ритмом (Уровень доказанности: С)

Third degree AV block and progressive second degree AV block of any anatomical level in asymptomatic patients with AF and documented at least one (or more) pause of 5 seconds or more (Level of Evidence: C)

Third degree AV block and progressive second degree AV block of any anatomical level in patients after catheter ablation of the AV node or His bundle (Level of Evidence: C)

Third degree AV block and progressive second degree AV block of any anatomical level in patients with postoperative AV block if its resolution is not predicted after cardiac surgery (Level of Evidence: C)

Third degree AV block and progressive second degree AV block of any anatomical level in patients with neuromuscular diseases with AV block, such as myotonic muscular dystrophy, Kearns-Sayre syndrome, Leiden dystrophy, peroneal muscular atrophy, with or without symptoms (Level of Evidence: B )

Third degree AV block, regardless of the type and location of block, with associated symptomatic bradycardia (Level of Evidence: B)

Persistent third-degree AV block of any anatomical level with an escape rhythm of less than 40 beats per minute while awake - in patients with cardiomegaly, LV dysfunction, or an escape rhythm below the level of the AV node who do not have clinical manifestations of bradycardia (Level of Evidence: B)

AV block II or III degree, occurring during an exercise test in the absence of signs of coronary artery disease (Level of evidence: C)

Class IIa

Asymptomatic persistent third-degree AV block at any anatomic site, with a mean awake ventricular rate >40 beats per minute, especially with cardiomegaly or left ventricular dysfunction (Level of Evidence: B, C)

Asymptomatic AV block of the second degree, type II at the intra- or infragisial level, detected by EPI (Level of evidence: B)

Asymptomatic second degree AV block type II with narrow QRS. If asymptomatic second-degree AV block occurs with a widened QRS, including isolated RBBB, the indication for pacing moves to a Class I recommendation (see next section on chronic bifascicular and trifascicular block) (Level of Evidence: B)

AV block I or II degree with hemodynamic disturbances (Level of evidence: B)

Class IIb

Neuromuscular diseases: myotonic muscular dystonia, Kearns-Sayre syndrome, Leiden dystrophy, peroneal muscular atrophy with AV block of any degree (including AV block of the first degree), with or without symptoms, because there may be unpredictable disease progression and deterioration of AV conduction (Level of Evidence: B)

When AV block occurs due to the use of drugs and/or their toxic effects, when resolution of the block is not expected, even if the drug is discontinued (Level of Evidence: B)

First-degree AV block with a PR interval greater than 0.30 sec in patients with left ventricular dysfunction and congestive heart failure in whom a shorter A-V interval results in hemodynamic improvement, presumably by reducing left atrial pressure (Level of Evidence: C)

Class IIa

The absence of a visible connection between syncope and AV block when excluding their connection with

Ventricular tachycardia (Level of evidence: B))

Incidental detection during invasive EPS of an apparently prolonged HV interval >100 ms in asymptomatic patients (Level of Evidence: B)

Detection during invasive electrophysiological study of non-physiological AV block below the His bundle, developing during stimulation (Level of Evidence: B)

Class IIc

Neuromuscular diseases such as myotonic muscular dystonia, Kearns-Sayre syndrome, Leiden dystrophy, peroneal muscular atrophy with fascicular block of any degree, with or without symptoms, because there may be an unpredictable increase in atrioventricular conduction disturbances (Level of Evidence: C)

Indications for planned hospitalization:

AV block II-III degree

Indications for emergency hospitalization:

Syncope, dizziness, hemodynamic instability (systolic blood pressure less than 80 mm Hg).

Information

Sources and literature

1. Minutes of meetings of the Expert Commission on Health Development of the Ministry of Health of the Republic of Kazakhstan, 2014
   1. 1. Brignole M, Auricchio A. et al. 2013 ESC The Task Force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA). Guidelines on cardiac pacing and cardiac resynchronization therapy. European Heart Journal (2013) 34, 2281–2329. 2. Brignole M, Alboni P, Benditt DG, Bergfeldt L, Blanc JJ, Bloch Thomsen PE, van Dijk JG, Fitzpatrick A, Hohnloser S, Janousek J, Kapoor W, Kenny RA, Kulakowski P, Masotti G, Moya A, Raviele A, Sutton R, Theodorakis G, Ungar A, Wieling W; Task Force on Syncope, European Society of Cardiology. Guidelines on management (diagnosis and treatment) of syncope-update 2004. Europace 2004;6:467 – 537 3. Epstein A., DiMarco J., Ellenbogen K. et al. ACC/AHA/HRS 2008 guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2008;117:2820-2840. 4. Fraser JD, Gillis AM, Irwin ME, Nishimura S, Tyers GF, Philippon F. Guidelines for pacemaker follow-up in Canada: a consensus statement of the Canadian Working Group on Cardiac Pacing. Can J Cardiol 2000;16:355-76 5. Gregoratos G, Abrams J, Epstein AE, et al. ACC/AHA/NASPE 2002 17 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices-summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee to Update the 1998 Pacemaker Guidelines). J Am Coll Cardiol. 40: 2002; 1703–19 6. Lamas GA, Lee K, Sweeney M, et al. The mode selection trial (MOST) in sinus node dysfunction: design, rationale, and baseline characteristics of the first 1000 patients. Am Heart J. 140: 2000; 541–51 7. Moya A., Sutton R., Ammirati F., Blanc J.-J., Brignole M., Dahm, J.B., Deharo J-C, Gajek J., Gjesdal K., Krahn A., Massin M., Pepi M., Pezawas T., Granell R.R., Sarasin F., Ungar A., ​​J. Gert van Dijk, Walma E.P. Wieling W.; Guidelines for the diagnosis and management of syncope (version 2009). Europace 2009. doi:10.1093/eurheartj/ehp29 8. Vardas P., Auricchio A. et al. Guidelines for cardiac pacing and cardiac recynchronization therapy. The Task Force for Cardiac Pacing and Cardiac Recynchronization Therapy of the European Society of Cardiology. Developed in Collaboration with the European Heart Rhythm Association. European Heart Journal (2007) 28, 2256-2295 9. Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). J Am Coll Cardiol. 48: 2006; e247–e346 10. Bockeria L.A., Revishvili A.Sh. et al. Clinical recommendations for electrophysiological studies and catheter ablation and for the use of implantable antiarrhythmic devices. Moscow, 2013

   
   Disclosure of no conflict of interest: absent.

   Reviewer:
   Madaliev K.N. - Head of the Arrhythmology Department of the RSE at the Scientific Research Institute of Cardiology and Internal Medicine, Candidate of Medical Sciences, cardiac surgeon of the highest category.

   Conditions for reviewing the protocol: Once every 5 years, or upon receipt of new data on the diagnosis and treatment of the corresponding disease, condition or syndrome.

   
   

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Distinguish 2 types of 2nd degree AV block: type I, which is a relatively harmless cardiac arrhythmia, and which is considered a serious disorder that requires additional research.

AV block II degree, type I (Mobitz I, Wenckebach periodics)

With this type of AV block we are talking about the so-called Wenckebach period. The PQ interval is initially normal.

With subsequent heart contractions, it gradually lengthens until the ventricular complex (QRS complex) falls out, since the conduction time in the AV node turns out to be too long and conduction of the impulse through it becomes impossible. This process is repeated.

AV block II degree, type I (Wenckebach period).
On the upper ECG the Wenckebach periodic is 3:2. On the lower ECG, the Wenckebach 3:2 periodic changed to a 6:5 periodic.
Long registration. Paper speed 25 mm/s.

Second degree AV block, type II (Mobitz II)

With this blockade, every 2nd, 3rd or 4th impulse from the atrium (P wave) is carried out to the ventricles. Such rhythm disturbances are referred to as AV block 2:1, 3:1 or 4:1. On the ECG, despite the fact that P waves are clearly visible, the corresponding QRS complex appears only after every 2nd or 3rd wave.

As a result, with a normal atrial contraction rate, severe bradycardia may occur, requiring implantation of a pacemaker.

AV block with Wenckebach periodicity can be observed with vegetative-vascular dystonia and ischemic heart disease, while cardiac arrhythmias of the Mobitz type II are observed only with serious organic damage to the heart.

Second degree AV block (Mobitz type II).
A 21-year-old patient who had myocarditis. Only every 2nd atrial impulse is conducted to the ventricles.
The ventricular contraction frequency is 35 per minute. Complete blockade of PNPG.

Training video for detecting AV block and its degrees on an ECG

If you have problems watching, download the video from the page

Normally, the human heart rate is 60-80 beats per minute. This rhythm sufficiently ensures blood supply to the vessels at the time of heart contraction in order to fully meet the oxygen needs of the internal organs.

The normal conduction of electrical signals is due to the coordinated work of the conducting fibers of the myocardium. Rhythmic electrical impulses are generated in the sinus node, then travel along the atrial fibers to the atrioventricular junction (AV node) and further along the ventricular tissue (see image on the left).

A block to conduction of an impulse can occur at each of the four levels. Therefore, they highlight , intraatrial, atrioventricular And . Intraatrial blockade does not pose a danger to the body; sinoatrial blockade can be a manifestation of sick sinus syndrome and be accompanied by severe bradycardia (rare pulse). Atrioventricular (AV, AV) blockade, in turn, can lead to severe hemodynamic disturbances, if conduction disturbances in the corresponding node of 2 and 3 degrees are detected.

Statistical data

According to WHO statistics, the prevalence of AV block based on the results of daily ECG monitoring reaches the following figures:

• In healthy young people, 1st degree blockade is recorded in up to 2% of all subjects,
• In young people with functional or organic pathology of the heart and blood vessels, 1st degree blockade is recorded in 5% of all cases,
• In persons over 60 years of age with underlying heart pathology, 1st, 2nd and 3rd degree AV block occurs in 15% of cases,
• In persons over 70 years of age - in 40% of cases,
• In patients with myocardial infarction, 1st, 2nd or 3rd degree AV block is recorded in more than 13% of cases,
• Iatrogenic (drug) AV block occurs in 3% of all patients,
• Atrioventricular block is the cause of sudden cardiac death in 17% of all cases.

Causes

1st degree AV block can occur normally in healthy people, if there is no background myocardial damage. In most cases it is transient (transitory). This type of blockade often does not cause clinical manifestations, and therefore is detected during a routine ECG during preventive medical examinations.

Also, grade 1 can be found in patients with hypotensive type, when parasympathetic influences on the heart predominate. However, persistent 1st degree blockade may indicate a more serious heart pathology.

Grades 2 and 3 in the vast majority of cases indicate the presence of organic myocardial damage in the patient. These diseases include the following (according to the frequency of blockade detection):

Prevention of complications includes not only measures initially aimed at the occurrence of severe cardiovascular pathology. Timely consultation with a doctor, complete diagnosis and competent treatment will help to identify the blockade in time and avoid the development of complications.

Disease prognosis

Prognostically 1st degree AV block is more favorable than grades 2 and 3. However, in the case of correctly selected therapy for grades 2 and 3, the risk of complications is reduced, and the quality of life and its duration in patients improves. An installed pacemaker, according to a number of studies, significantly increases patient survival in the first ten years.

The human heart, like many other living creatures belonging to mammals, consists of a right and left part, each of which has an atrium and a ventricle. Blood from the entire body, namely from the systemic circulation, flows first into the right atrium, and then into the right ventricle, then through the vessels to the lungs.

Blood flow in the heart ensures the functioning of its conduction system. It is thanks to it that the heart beats correctly - the timely contraction of the atria and ventricles and the flow of blood through them. If there is a disturbance in the transmission of nerve impulses between the atria and ventricles, the latter contract too slowly or untimely - after a long period of time after the contraction of the atria.

In this case, if there are no serious disturbances in the blood flow in the organs, it is necessary to eliminate the underlying disease, and the disturbance in the conduction of the excitation wave will completely disappear without treatment.

If the cause of the disorder is organic (there is a pathology in the heart muscle), there is no complete cure.
In the absence of symptoms, observation is indicated, as there is a risk of increasing the degree of blockade. And if the patient has clinical manifestations, treatment and constant monitoring are necessary.

With therapy, it is possible to achieve good functional results with almost complete restoration of ability to work for second-degree blockade of type 1, less often - type 2.

In the case of third degree blockade, 90% of patients already have cardiovascular disease, and quality of life is only partially improved. The main goal of treatment in this group is to reduce the risk of cardiac arrest.

Click on photo to enlarge

First degree:

• observation in dynamics,
• do not use drugs that impair the conduction of the excitation impulse (listed in the medicinal causes of blockades),
• if there is insufficiency of the left ventricle caused by cardiac pathology, installation of an electrical cardiac stimulator.

Second degree, type 2:

• in the presence of clinical manifestations - temporary, and then, after preparation, permanent electrical stimulation of cardiac activity,
• in the absence of symptoms, planned pacemaker implantation due to the high risk of developing complete heart block.

Why is AV block dangerous?

The degree of danger of atrioventricular block depends on its severity. Mild forms of conduction disturbances may be asymptomatic, while moderate forms require clarification of the causes and treatment to prevent heart failure. With complete blockade, instant death from cardiac arrest can occur. That is why disturbances in nerve conduction in the heart cannot be ignored, even if there are no severe signs of the disease at the moment.

Causes of 2nd degree AV blocks Mobitz types I and II

This rhythm is so easy to remember once you identify its “identity.” Note the PR interval on the ECG strip. See how the PR interval gradually lengthens and then suddenly there is no QRS complex and then the pattern starts all over again? This is the key to understanding Wenckebach.

This rhythm is CYCLIC and will always gradually increase PR intervals until the QRS complex disappears, and then it will repeat. You will also have the following with this rhythm:

• P-waves R-wave will be IRREGULAR
• PR intervals ABNORMAL
• Missing QRS complex
• Cyclical

Many people like to confuse this rhythm with Wenckebach and the third degree. However, there are some major differences. The fact that the rhythm is not cyclical does not have a pattern. Second, his QRS complexes will be IRREGULAR, which is the opposite of 3rd degree heart block. Third, it may have NORMAL PR intervals when 3rd degree heart block does not contain PR intervals.

Notice in the bar above: the p waves are nice and regular, while there are some missing QRS complexes that make the R wave irregular. In addition, there is no pattern of p-wave elongation. So, the things that need to be removed from this rhythm are:

• P-waves will be regular, however P-waves will NOT
• The PR interval will measure normally (most of the time)
• NO Sample
• Missed QRS complexes after p-waves randomly

AV blockades are based on Art. 2. Mobitz types I and II often underlie organic diseases:

• IHD – during ischemia, the myocardium experiences a prolonged lack of oxygen (hypoxia), which results in microscopic areas of tissue that do not conduct electrical impulses (and do not contract fully). If such foci are concentrated near the boundaries of the atria and ventricles, an obstacle appears in the path of impulse propagation - a blockade occurs and develops;
• myocardial infarction (acute and subacute) – a similar mechanism, but areas of dead tissue also appear;
• heart defects (congenital or acquired) – a serious disorder in the structure of muscle fibers leading to structural changes in the chambers of the heart, cardiomyopathies;
• arterial hypertension (long-term) – leads to hypertrophic or obstructive left ventricular cardiomyopathy.

The causes of 2nd degree atrioventricular block can also be isolated diseases of the conduction system of the heart - Lenegra's disease and Lev's disease, calcification of valve rings, infiltrative myocardial diseases - amyloidosis, sarcoidosis, hemochromotosis. The cause of congenital AV block is stage 2. the mother may develop systemic lupus erythematosus.

Inflammatory diseases also become causes of 2nd degree AV block: infective endocarditis, myocarditis (Lyme disease, Chagas disease, rheumatism, measles, tuberculosis, mumps). Endocrinological diseases, such as diabetes mellitus (especially type 1), hypothyroidism, as well as gastric ulcers, primary adrenal insufficiency are also the causes of 2nd degree AV blockades.

The causes of 2nd degree AV blockade can be: metabolic disorders - hyperkalemia, hypermagnesemia, damage to the AV node during heart surgery, cardiac catheterization, catheter destruction, mediastinal irradiation, neuromuscular diseases (for example, atrophic myotonia). The causes of 2nd degree AV block can be traumatic brain injury, intoxication and poisoning, infectious diseases, and fever.

Tumors (mesothelioma, melanoma, lymphogranulomatosis, rhabdomyosarcoma), collagenoses (rheumatoid arthritis, systemic scleroderma, systemic lupus erythematosus, Reiter's syndrome, ankylosing spondylitis, polymyositis) can also act as causes of stage 2 AV blocks. Neurogenic causes of transient and permanent 2nd degree AV blocks in young and elderly people can be provoked by diseases such as carotid sinus syndrome or vasovagal reactions.

In general, the causes of 2nd degree AV block are the development of idiopathic fibrosis and sclerosis of the conduction system of the heart in various diseases. This includes a whole list of diseases associated with rheumatic processes in the myocardium, syphilitic damage to the heart, cardiosclerosis, infarction of the interventricular septum, and diffuse connective tissue diseases.

Regardless of the causes of 2nd degree AV block, treatment usually comes down to installing a pacemaker. Drug treatment is not carried out independently. In rare cases - when the cause of the disease is the use of medications - treatment comes down to stopping the medication.

Sinoauricular block

First degree AV block may be a normal physiologic finding in young patients. It is often diagnosed in regularly training athletes, and is also considered normal for them. With this type of blockade, a person usually does not have any noticeable symptoms indicating a heart problem. 1st degree AV block in the absence of signs of the disease, as a rule, does not require treatment, but it may be necessary if there are other abnormalities in the heart.

Also in this case, the doctor may prescribe repeated ECGs, daily ECG monitoring and additional studies, such as echocardiography (ultrasound of the heart). On the electrocardiogram, first degree atrioventricular block is manifested by an increase in the interval between the P and R waves, while all P waves are normal and are always followed by QRS complexes.

The most common causes of such a disorder as AV block are increased vagal tone in athletes, sclerosis and fibrosis of the cardiac conduction system, pathology of the heart valves, myocarditis, myocardial infarction, electrolyte disorders and the use of certain medications, such as cardiac glycosides (Digoxin) , "Korglikon", "Strofanthin"), calcium channel blockers ("Amlodipine", "Verapamil", "Diltiazem", "Nifedipine", "Cinnarizine"), beta blockers ("Bisoprolol", "Atenolol", "Carvedilol" ).

1st degree atrioventricular block, as well as 2nd degree block of the first type, is usually not accompanied by any symptoms. However, with Moritz type 1 blockade, dizziness and fainting are observed in some cases. The second type of the second degree is manifested by the same symptoms, as well as clouding of consciousness, pain in the heart and a feeling of cardiac arrest, prolonged fainting.

Diagnosis of atrioventricular block is carried out using electrocardiography. Often, 2nd degree AV block (as well as 1st degree) is discovered accidentally during an ECG without complaints during a preventive medical examination. In other cases, diagnosis is carried out in the presence of any symptoms that may be associated with problems in the nerve impulse conducting system of the heart, for example, dizziness, weakness, darkening of the eyes, fainting.

If a patient is diagnosed with AV block by ECG and there are indications for further examination, the cardiologist usually recommends daily ECG monitoring. It is carried out using a Holter monitor, which is why it is also often called Holter monitoring. For 24 hours, there is a constant continuous recording of the ECG, while the person leads his usual and characteristic way of life - moves, eats, sleeps. The examination is non-invasive and causes virtually no discomfort.

After the end of the electrocardiogram recording, the data from the monitor is analyzed and an appropriate conclusion is issued. The advantage of this diagnostic method, compared to a conventional short ECG recording, is that it is possible to find out with what frequency blockades occur, at what time of day they are recorded most often and at what level of activity of the patient.

Having answered the question “what is heart block,” it is necessary to understand what they are and how they are divided in medical practice.

1st degree blockade is characterized by a slowdown in the passage of the impulse, but each contraction of the atria, albeit with a delay, corresponds to a contraction of the ventricles. In most cases, the disorder is localized at the level of the AV node; in only 20%, damage to the pathways is detected at the level of the His bundle elements.

3rd degree block, or complete AV block - the excitation impulse from the atria to the ventricles does not pass at all, they contract separately from each other with different rhythms. Atria - more often than 60 contractions per minute, since the impulse comes from the sinus node, ventricles - less often (the rhythm can decrease to 20).

Heart blocks can also be:

• physiological (5–10%) – the norm for people with a predominant influence of the parasympathetic nervous system, athletes,
• pathological, or organic, associated with damage to the myocardial conduction system (more than 90% of all blockades).

The article discusses only pathological changes in the conduction of excitation.

Arntioventricular block is a disease that disrupts the transmission of nerve impulses to the conduction system of the heart.

The disease may have a transverse form, which is characterized by a disorder, since the Ashofa-Tavara node is affected.

With longitudinal blockade, conduction is also impaired. Arntioventricular block occurs with an increase in the PQ interval, more than 0.2 s. It is diagnosed in 0.5 percent of young patients.

In this case, there are no signs of heart disease. This disease can also occur in elderly patients. The most common cause of its appearance at this age is an isolated disease of the conduction system.

The most common disorder is at the level of the AV node. There is also a decrease in the AV node itself. 1st degree AV block can be chronic, which requires constant monitoring of the patient, as well as the use of certain treatment methods.

The cause of atrioventricular block in isolated diseases of the cardiac conduction system. These diseases include Lev's disease or Lenegra's disease.

Find out what AV block is in this video.

There are a huge number of reasons due to which this pathological condition occurs.

Atrioventricular block may occur while taking certain medications:

• Deta-blockers;
• Certain calcium antagonists;
• Digoxin;
• Antiarrhythmic drugs that have quinidine action.

With congenital heart defects, in most cases, AV block is observed, the diagnosis of which is very often carried out during the course of lupus in females. If the patient experiences transposition of the great arteries, this can lead to atrioventricular block.

Also, the cause of this pathological condition is defects in the interatrial septa.

In most cases, the development of the disease is observed in myocardial diseases:

• Sarcoidosis;
• Amyloidosis;
• Hemochromatosis.

The development of pathology can be observed with myocarditis, infective endocarditis, which belong to the category of inflammatory diseases.

With metabolic disorders: hyperkalemia and hypermagnesemia, the development of atrioventricular block is observed. In primary adrenal insufficiency, this process can also be observed.

The cause of atrioventricular block is very often damage to the AV node, which occurs as a result of surgical intervention in the heart, catheterization of the organ, irradiation of the mediastinum, catheter destruction.

The presence of tumors, namely melanoma, mesothelioma, rhabdomyosarcoma, lymphogranulomatosis, can also contribute to the development of AV block.

There are several neurogenic reasons why the pathological condition may appear. These include vasovagal reactions. The disease can also occur as a result of carotid sinus syndrome.

Atrioventricular block is a fairly serious pathological process occurring in the heart. It can appear as a result of the development of various diseases and pathologies.

Treatment of 1st degree AV block consists of constant doctor monitoring of the patient only if it occurs without symptoms. If the pathological condition appears as a result of taking certain medications, then their dose is adjusted or completely discontinued. Very often, the pathology is caused by cardiac glycosides, B-blockers, and antiarrhythmic drugs.

Atrioventricular block, which has a cardiac origin and occurs as a result of the development of myocardial infarction, cardiosclerosis, myocarditis, etc., requires the use of B-agonists for treatment. Most often, patients are prescribed Isoprenaline, Orciprenaline and their analogues. After completing the course of medication, a pacemaker is implanted.

In order to prevent a Morgana-Adams-Stokes attack, subvaginal use of Izadrin is carried out. Atropine can also be administered subcutaneously or intravenously. If a patient is diagnosed with congestive heart failure, then they are prescribed cardiac glycosides, diuretics, and vasodilators.

The first of the medications must be taken as carefully as possible. If the patient has a chronic form of atrioventricular block, then this requires the use of symptomatic therapy. Most often in this case, Belloid, Teopek, Corinfar are prescribed.

They are committed to installing an electrical pacemaker, with the help of which the normal rhythm and heart rate are restored. If a patient has Morgan-Adams-Stokes attacks, then he must undergo implantation of an endocardial pacemaker.

ECG with complete blockade

Of all heart blocks, this is the worst for the patient. This requires serious interventions. In this rhythm, the atria and ventricles do NOT beat together and work independently of each other. Therefore, the important "distinguishing marks" to be taken away from this rhythm are the following:

• P-waves will be regular And P-waves will be regular
• The P wave will not accompany the QRS complexes and vice versa, therefore there is no connection between the atria and ventricles
• You cannot measure the PR interval because the atria and ventricles are independent

• unchanged atrial waves at regular intervals, emphasizing the preserved atrial rhythm;
• the distances between the ventricular complexes are also equal, but they have an independent rare rhythm;
• the P wave (atrial) can be located anywhere and is in no way connected with R.

When the His bundle is destroyed, impulses can arise in one of the legs and be transmitted first to one ventricle, then to the other. The ECG picture will be similar to ventricular extrasystoles.

If the pathological process has not yet ended with scarring, then the ECG can be used to observe the transition from incomplete blockade to the formation of complete blockade.

The heart is undoubtedly one of the most important organs in the human body. And the main thing, if we talk about the cardiovascular system - being a kind of pump, it pumps blood through the vessels, providing tissues with nutrients and oxygen. Therefore, it is necessary for a person that the heart works correctly and without failures. But, unfortunately, this is not always the case. One of the ailments is heart block.

To understand the causes of heart block, you first need to understand a little about how it works. The normal functioning of the heart is carried out due to electrical impulses emanating from the sinoatrial node. They, in turn, enter the atria, which contract in response and transmit it further, towards small branches, causing heart contractions.

What is heart block and why does it occur? This is the name of one of the disorders of this process, characterized by reduced activity of the above-mentioned atrial node - as a result, the interval between contractions increases significantly.

The prerequisites for the appearance of symptoms of heart block are other diseases, one way or another related to the circulatory system or tissue conductivity. These include diseases such as heart tumors, myxedema, diffuse connective tissue diseases, myocardial infarction, some types of myocarditis and others.

In healthy people, with frequent overstimulation of the vagus nerve, incomplete heart block can also develop: it is provoked by excessive physical activity, less often by stress. In very rare cases, it is noted to be congenital; when intrauterine pathologies appear, the child in such cases is immediately diagnosed with heart disease.

Oddly enough, heart block is different and manifests itself to varying degrees in everyone, which depends on individual predisposition, the severity of the disease and many other factors. If we talk specifically about the harmfulness of impaired heart contractions, then there are two main types of the course of the disease: partial and complete heart block.

Often they are completely insignificant or are expressed in the form of mild dizziness or mild malaise. The only way to detect rhythm disturbances is at an appointment with a cardiologist or when visiting a clinic.

It would seem that it looks insignificant and, in general, there is no particular danger, but it is not for nothing that the phrase heart block sounds so frightening - any disorders of the circulatory system negatively affect a person and can get worse.

And from here new symptoms and ailments emerge:

• appearance;
• darkening of the eyes;
• varying degrees of dizziness;

All of them are in one way or another associated with impaired blood supply: the heart becomes unable to sufficiently supply the human body with oxygen. Another danger of sudden heart block is cerebral ischemia, which causes an attack of MAS (), loss of consciousness, accompanied by seizures similar to epileptic seizures.

The prerequisites for such an attack are: severe heat in the head, weakness, severe pallor and loss of consciousness. In this case, the blockade is no longer called complete, but instantaneous - from random to periodic, manifesting itself at the level of automatism. Often, systematic manifestations of MAS end in the death of the patient.

Characteristic symptoms

Type of heart block	Clinical manifestations
1st degree	None Diagnosis: incidental finding during electrocardiography Lead a full life, without any restrictions
2 degrees 1 type	None Rarely – there are sensations of interruptions in the heart’s function There are no changes in the usual way of life
2 degrees 2 types	Periodic or constant form of slowing of myocardial contraction frequency Feeling like your heart has stopped inside Irregularity of heart rate (interruptions) Weakness Fatigue Fatigue Dizziness Changes in vision (floaters, spots, circles) Darkness in the eyes, fainting due to physical exertion Chest pain – rare Cannot perform moderate to heavy workloads It is dangerous to work under conditions of increased attention due to the risk of loss of consciousness
3 degrees	The same as for the second degree of type 2 There are pains in the heart Decrease in myocardial contraction frequency to less than 40 per minute In 90% of cases, congestive failure of cardiac function (swelling, shortness of breath, decreased exercise tolerance, unstable blood pressure) May have difficulty performing household chores; otherwise, assistance is required Without treatment - completely disabled

Symptoms of 1st degree AV block may be scanty or absent altogether
. However, patients often note such signs as increased fatigue, general weakness, a feeling of shortness of breath during physical activity, dizziness and a feeling of interruptions in the heart, pre-syncope with flickering spots before the eyes, ringing in the ears and other harbingers of what is now the person will lose consciousness. This is especially pronounced when walking or running quickly, since a blocked heart is unable to provide adequate blood flow to the brain and muscles.

2nd and 3rd degree AV block is much more pronounced
. During a rare heartbeat (less than 50 per minute), the patient may lose consciousness for a short period of time (no more than 2 minutes). This is called (Morgagni-Edams-Stokes) and is life-threatening, since this type of conduction disorder can lead to complete.

But usually the patient regains consciousness, bypass and additional conduction pathways “turn on” in the myocardium, and the heart begins to contract at a normal or slightly lower frequency. However, a patient with an attack of MES must be promptly examined by a doctor and hospitalized in the cardiology, arrhythmology or therapeutic department of the hospital, since the issue of the need to install a pacemaker, or artificial pacemaker, will subsequently be decided.

In extremely rare cases, a patient may never regain consciousness after an attack of MES, in which case he should be taken to the hospital as quickly as possible.

Diagnosis of AV block

If the patient has the above-described complaints, call an ambulance or examine a therapist
(cardiologist/arrhythmologist) in a local clinic with an electrocardiogram.

The ECG will immediately show signs such as a decrease in the parameter reflecting ventricular contractions (bradycardia), an increase in the distance on the film between the P waves responsible for atrial contractions and the QRS complexes responsible for ventricular contractions. In case of 2nd degree AV block, Mobitz type 1 and Mobitz type 2 are distinguished, which are manifested on the ECG by periodic loss of ventricular contractions.

After the patient is hospitalized in the department of therapy, cardiology or arrhythmology,
He undergoes instrumental methods of further examination:

• , to clarify the nature of myocardial pathology, if any; the contractility of muscle tissue and the ejection fraction of blood into large vessels are also assessed,
• Blood pressure and ECG during the day with subsequent assessment of the degree of blockade, the frequency of its occurrence and its relationship with physical activity,
• Exercise testing is used in patients with myocardial ischemia and chronic heart failure.

In any case, only a doctor can prescribe an exact examination plan for a patient during an in-person examination.

Features of treatment for children

It is not always the case that first-degree atrioventricular block, like the second, requires medical intervention. In the first case, there is usually no need for therapeutic measures. Also, for type 2 to type 1 (Moritz 1), therapy is usually not carried out, although additional tests to identify concomitant heart problems may be recommended.

Treatment of AV block is necessary for the second degree of Moritz type 2, as well as for partial or complete block of the third degree, since such a significant conduction disorder can lead to sudden death. The main method of correcting abnormal heart function is to install a pacemaker (pacemaker), temporary or permanent, in the patient.

• Arterial hypertension;
• Congestive heart failure;
• Angina pectoris with complete AV block.

If the patient has a ventricular rate of less than forty per minute, then he must undergo the procedure.

Treatment of atrioventricular block involves the use of drug therapy. If it is ineffective, surgical intervention is used.

According to statistics, atrioventricular block in children occurs in 12 percent of cases. At this age, the disease very often progresses in children. The cause of fetal AV is a developmental pathology inside the mother's womb.

Very often, fetal damage occurs as a result of various infections: streptococci, staphylococci, chlamydia, etc. In some cases, the disease occurs as a result of a genetic predisposition. If surgery is performed to correct heart defects, this can also lead to atrioventricular block.

Children who develop this disease become tired very quickly. Young patients who can speak complain of headaches and pain in the heart area. In some cases, children may experience lack of concentration. When exercising, the child experiences shortness of breath. He becomes very weak. If the baby is critically ill, an artificial pacemaker is implanted.

Treatment of atrioventricular block in children directly depends on its causes. Most often, in the first stage of the disease, no treatment is performed. Most often, children are treated using drug therapy.

Atrioventricular block in children is diagnosed very often. If this disease does not progress and does not have concomitant diseases, then the child is simply monitored. Otherwise, medications or surgery are used.

It is necessary to treat blockades in case of clinical manifestations of hypoxia and the risk of developing heart failure. Most patients require therapy for the underlying disease. The prognosis also depends on the spread of atherosclerosis, cure of sepsis or myocarditis, successful treatment of hypertension, acute myocardial infarction.

In mild cases, patients undergo a test with Atropine. If the signs of blockade disappear on the ECG after its action, it means that there is an increase in the tone of the vagus nerve. To relieve its effects, drops of Zelenin, Bellataminal, and rectal suppositories with belladonna have a good effect.

In the case of a Morgagni-Edams-Stokes attack, treatment of heart block requires such potent substances as Ephedrine, Adrenaline. They are injected into the subclavian vein. Sometimes it is necessary to carry out resuscitation measures and indirect cardiac massage.

In patients with complete blockade and frequent attacks, cardiac pacing is vitally necessary using pacemaker implantation. It is sutured under the pectoral muscle. The device provides a given rhythm and frequency of contractions and allows the use of cardiac glycosides in treatment to compensate for chronic failure.

Diagnosis of various new blockades signals the unfavorable course of the underlying disease, allows you to change treatment, and take timely measures. Patients must undergo an ECG examination at least twice a year and be observed by a doctor.

What is a heart block?

The cause of AV blockades can be isolated disease of the conduction system (Lenegra disease), myocardial infarction (blockade, as a rule, manifests itself in the first 24 hours), coronary heart disease (CHD), congenital and acquired heart defects, long-term hypertension, cardiosclerosis, some endocrinological diseases, etc. The causes of AV block can also be functional (taking certain types of medications, intense exercise).

Functional causes of AV heart block, such as taking β-blockers, cardiac glycosides (digitalis), antiarrhythmic drugs (quinidine), intravenous administration of drotaverine and papaverine, calcium channel blockers (diltiazem, verapamil, corinfarum), lithium, can be eliminated by avoiding from taking medications. In general, the functional reasons for the occurrence and development of AV blockades are caused by an increase in the tone of the parasympathetic part of the nervous system.

The causes of AV block in children are congenital heart defects and certain diseases of the mother during pregnancy (for example, systemic lupus erythematosus in the mother). Often the congenital form of atrioventricular block in children is caused by the absence of sections of the conduction system (between the AV node and the ventricles, between the atrium and the AV node, between both legs of the His.

The most important thing in the case of such diseases is to never self-medicate. Consultation with a cardiologist is required.

Treatment of heart block directly depends on what causes it and what type it is. For example, 1st degree atrioventricular block does not require treatment as such - observation of a specialist is sufficient. Only in case of deterioration or complications, drug therapy can be started. If the blockade is provoked by some other disease, then the main forces should be focused on it as the source of the problem.

For other degrees of heart block, treatment is selected individually. For example, for paroxysmal it is sympathomimetic drugs or atropine, but for distal, tablets may not have the desired effect at all and electrical stimulation may be needed. In case of a sudden attack, you can take a whole or half of a Euspiran tablet. Patients are often given atropine. There is no need to neglect drug treatment, it can contribute to the transition of a complete blockade to a partial one.

If the patient notices weakness, fatigue and decreased activity, accompanied by low blood pressure and a rare pulse (at least 55 per minute), he can take courses of tinctures of ginseng, schisandra or eleutherococcus as general strengthening and tonic drugs, but only in consultation with the attending physician .

With 2nd and 3rd degree AV block, especially accompanied by attacks or MES equivalents, the patient requires full treatment.

Thus, treatment of the underlying disease of the heart or other organs comes to the fore. While the underlying cause of the block is being diagnosed and the first steps are being taken to treat the block, the patient is prescribed drugs such as atropine, isadrine, glucagon and prednisolone (subcutaneously, in tablets or intravenously, depending on the drug). In addition, it is possible to prescribe teopek, aminophylline or corinfar (nifedipine, cordaflex) in tablets.

As a rule, after treatment of the underlying disease, conduction through the AV node is restored. However, a formed scar in the area of ​​the node can cause persistent conduction disturbance in this place, and then the effectiveness of conservative therapy becomes questionable. In such cases, it is preferable for the patient to install one that will stimulate contractions of the atria and ventricles at a physiological frequency, ensuring the correct rhythmic pulse.

The operation to install an pacemaker can currently be performed free of charge according to quotas obtained from the regional departments of the Ministry of Health.

Preparing for ECS installation

Preparation for pacemaker implantation includes, in addition to electrocardiography, echocardiography - ultrasound examination of the heart. EchoCG allows you to visualize the wall, cavities and septa of the heart and detect any primary diseases that could be the cause of AV block, such as valve pathology.

If a cardiologist finds heart problems during an ultrasound examination, concomitant therapy is carried out in parallel with the treatment of atrioventricular block. This is especially important in cases where these pathologies are the cause of conduction disorders. Standard clinical tests are also prescribed - blood and urine tests.

Implantation of pacemaker

Installation of a pacemaker for a diagnosis such as AV block is a planned surgical procedure. It can be performed either under general anesthesia or local anesthesia. The surgeon passes electrodes through the subclavian vein through the vessels towards the heart, which are fixed there. The device itself is sewn under the skin using a special technique. Stitches are placed on the wound.

The pacemaker is an artificial pacemaker substitute that conducts impulses from the atria to the ventricles and normalizes the heartbeat. Thanks to periodic or continuous stimulation, the chambers contract in the correct order and at the correct interval, the heart fully performs its pumping function.

There is no congestion or sudden changes in pressure in the circulatory system, and the risk of symptoms such as dizziness, loss of consciousness, and others that typically occur in patients diagnosed with AV block is significantly reduced, as is the risk of sudden death from cardiac arrest. cardiac activity.

After operation

The postoperative period, if there are no other health problems complicating its course, is usually not accompanied by any serious restrictions. The patient is allowed to go home for 1-7 days, having previously conducted some studies. Care for the wound in the area of ​​the implanted body of the device is carried out according to the recommendations of the doctor.

In the first weeks after implantation of a pacemaker, it is recommended to avoid physical activity and also take care of the suture area (sports, if there are no contraindications, can be started after a few months, be sure to consult a doctor). A follow-up consultation with a cardiologist is scheduled 1 month after the procedure. Then the check is carried out six months later and again a year from the day of implantation, and then annually.

The operating time of the pacemaker depends on many factors. On average, this period is 7-10 years, and in children it is usually much shorter, which is due, among other things, to the growth of the child’s body. The operation of the stimulator, as well as its programming for a specific patient, is monitored by a doctor. Checking the functionality of the device must be carried out in a timely manner.

Also, if necessary, the program—the specified operating parameters—is adjusted. This may be necessary if the pacemaker is not performing its intended tasks: the heart rate is too low or high and/or the patient is not feeling well.

The main reason for ECS failure is a decrease in battery capacity - its discharge. In such cases, the device must be replaced with a new one, and consultation with a cardiologist is required. The electrodes located in the cavity of the heart usually remain for life and, if they work properly, do not require replacement, allowing a person to live a full life, despite heart problems.

Sinoauricular block

• sinoauricular,
• atrial,
• atrioventricular (AV),
• intraventricular.

The most common occurrence is atrioventricular block and conduction disturbances in individual bundle branches (two bundles of fibers into which the conduction system splits inside the ventricles).

The patient's pulse is characterized by the “loss” of the next shock wave. Physical activity in some cases eliminates the blockade, the same is observed after the administration of atropine-containing drugs.

It is important for the doctor to distinguish sinoauricular block from respiratory arrhythmia. When breathing deeply against the background of a delay, the rhythm slows down. And the conductivity block does not affect the frequency.

An ECG examination reveals a loss of contractions and a pause equal to two cardiac cycles.

Sinoauricular heart block most often occurs when:

• increased tone of the vagus nerve;
• pressure, blow to the eyeballs or the area of ​​the carotid arteries;
• treatment with cardiac glycosides and quinidine drugs.

It is noted in mitral stenosis. It is considered one of the indirect signs of right atrium hypertrophy.

There are 2 types:

1. incomplete heart block - even with impaired conduction, most of the impulses, albeit delayed, reach the ventricles;
2. complete - due to a break in the conduction pathways, signals from the sinus node do not reach the ventricles.

In case of incomplete blockade, the ECG reveals slow conduction of the impulse from the atria to the ventricles. This may be unstable, functional (nervous) in nature, and depend on overexcitation of the vagus nerve.

Inflammatory heart diseases lead to myocarditis in rheumatism, diphtheria, and acute viral infections. In such cases, newly detected incomplete blockade is considered a sign of myocarditis.

Cardiologists pay attention to circulatory disorders in the area of ​​the sinus and atrioventricular nodes, which contributes to their weakness and organic damage to the conductive fibers. The blockade causes anatomical changes in a descending manner, spreading to the bundle branches. But an ascending type of lesion is possible, when the pathology, starting with a blockade of the leg, becomes complete.

Based on ECG signs and clinical course, it is customary to distinguish 3 degrees of impaired conduction during atrioventricular blockade.

The first degree reflects only the slow conduction of excitation along the atrioventricular bundle. This means that the time required from contractions of the atria to the ventricles increases from the normal 0.15–0.18 seconds. up to 0.2 sec. On the ECG, the PQ interval lengthens accordingly.

Stage 1 conduction disturbances are often observed in the midst of an acute rheumatic attack. After treatment it disappears. Persistent changes occur when:

• postmyocardial cardiosclerosis;
• atherosclerotic lesions of the coronary arteries (especially the branches of the right coronary artery);
• slow sepsis;
• syphilitic myocarditis.

When studying the role of the vagus nerve, the importance of the left trunk, which innervates most of the His bundle, was established.

Second degree atrioventricular heart block represents a progressive deterioration of conduction and exhaustion of the system. Samoilov-Wenckebach periods appear on the ECG - the loss of one contraction. Perhaps this will be every third, fourth or fifth ventricular systole.

Accordingly, the patient feels a change in the strength of the pulse beat. In clinical manifestations, you need to carefully look at the pulsation of the cervical vessels. When auscultating the heart, the doctor needs to keep his hand on the pulse at the same time, then you can feel the loss of contraction without an ECG.

Another type described by Wenckebach is characterized by loss of individual ventricular contractions with a preserved PQ interval. This confirms incomplete atrioventricular block with an atrial to ventricular ratio of 2:1, 3:1, or 4:1.

The third degree is known as a complete transverse block. Its detection, according to various statistical studies, ranges from 0.53 to 0.8% of all electrocardiographs performed.

The main cause is atherosclerosis (in 50–70% of cases). Conductivity is impaired due to low patency of the coronary vessels that feed the cells. About 5% of cases are caused by rheumatic inflammation, diphtheria. Much less often, blockade of the left ventricle of the heart accompanies myocardial infarction of the posterior wall, scarlet fever and other infections.

With complete blockade, the His bundle loses its conductive ability. The impulses that cause ventricular contraction occur below the site of injury. As a result, the atria continue to receive impulses from the sinus node and contract at their normal rhythm (60–80 beats per minute), while the ventricles “listen” to other instructions and work more slowly, regardless of the atria.

It has been proven that in the atrioventricular node the frequency of impulses is 50 per minute. If the focus is located above the site of division of the common bundle into the right and left legs, bradycardia reaches 25–20 per minute.

• conduction disturbances in one of the legs of the bundle after its division into right and left;
• from damage to the terminal Purkinje fibers.

When a block occurs in one of the legs, it is completely destroyed. The impulse from the sinus node passes along the preserved leg, captures the nearest ventricle, then passes along the interventricular septum to the other ventricle.

Damage to the left leg is more common, since it is supplied by the left coronary artery, which is more prone to the atherosclerotic process. ECG changes are found in elderly men with chronic coronary insufficiency. Much less often, blockade of the legs is a consequence of childhood infections, acute myocardial infarction, and rheumatism.

There is no characteristic clinical picture. It is important to take into account in diagnosis that blockade of the legs indicates the severity of myocardial damage in any disease.

The ECG shows:

• dilated and deformed ventricular complexes;
• change in the direction of the T wave.

The localization of the blockade is indicated by changes in typical standard and chest leads.

Depending on the course of the underlying disease, this type of blockade can be:

• full,
• incomplete,
• short-term
• permanent.

The cause of 1st degree AV block may be the use of medications that reduce the heart rate (HR). Such drugs should be taken with caution when AV blockade occurs. The disease itself (deviation) can only be detected on an electrocardiogram (ECG).

Causes of AV block 1st century. without underlying myocardial damage, they are not searched for, treatment is not prescribed, however, the patient is recommended to undergo regular medical examination, because the disease tends to progress. In most cases, AV block is 1st degree. is transient, does not manifest itself clinically, and its cause may also be vegetative-vascular dystonia of the hypotonic type.

The causes of transient AV blockades are often the abuse of medications, including their incorrect combination with each other. Increased physical activity, leading to increased activity of the vagus nerve, is also the cause of transient AV blocks during sleep.

Prevention of complications includes not only measures initially aimed at the occurrence of severe cardiovascular pathology. Timely consultation with a doctor, complete diagnosis and competent treatment will help to identify the blockade in time and avoid the development of complications.

When electrocardiography reveals an increase in PQ duration beyond 0.3 s, there is most likely a combination of deceleration with another block.

Impulse conduction delay of the 2nd degree is divided into two types according to Mobitz. Type 1 second-degree atrioventricular block is spoken of in the presence of the characteristic Samoilov-Wenckebach period, when from cycle to cycle there is an increase in the duration of PQ intervals, followed by a compensatory pause or the possible appearance of a replacement rhythm from an ectopic focus.

Atrioventricular blockade 2 stages. Type 2 is manifested by the sudden loss of one of the cycles. When decoding the cardiogram, the ratio of P waves to ventricular complexes is indicated.

This record characterizes the efficiency of excitation through the atrioventricular region and means that every second (2:1) or third (3:1) potential reaches its destination.

In the case of complete AV block (3rd degree), discoordinated contractions of the atria and ventricles are observed, up to cardiac arrest. This condition can only be compensated by the appearance of an ectopic rhythm from the underlying structures of the conduction system.

Regardless of the degree, the ECG may not register the presence of rhythm disturbances at the time of examination. Therefore, in some cases, in case of corresponding complaints, daily electrocardiographic monitoring is prescribed.

How to make a diagnosis

Type of procedure or study	What is shown or assessed?
Collecting anamnesis - complaints, timing of their appearance	Assessing the severity of the disease
Patient examination	Detection of slow heart rate (low heart rate)
Electrocardiography (ECG) – a graphic representation of contractions of all parts of the heart muscle	How does the impulse travel from the atria to the ventricles - shortening or lengthening the PQ interval Correspondence to each contraction of the atria (P wave), contraction of the ventricles (Q wave) Do the ventricles of the heart contract evenly (QRS complex)
ECG with vagal or drug tests	Assessment of the level of the impulse conduction block
24-hour heart rate monitoring (Holter)	Assessment of the course of the blockade (paroxysmal or chronic)
Electrophysiological study of the heart (EPS) through the esophagus - assessment of the conductivity of the electrical impulse by electrical stimulation of the atria	Assessment of impulse conduction in the area of ​​the atrioventricular node only, and therefore has limited use
EPI with intracardiac sensors is an invasive procedure, sensors are passed through the femoral arteries into the heart cavity and electrical stimulation of the heart is performed	A complete assessment of the conduction system of the heart muscle allows you to accurately determine the level of block and the degree of impairment
Ultrasound examination of the heart (echocardiography or ultrasound) through the chest or esophagus	An additional research method to determine the functional state of the myocardium and identify the cardiac cause of heart block