Arrhythmia

Arrhythmia is not a separate, independent disease, it is a group of symptoms united by one concept - a violation of the normal heart rhythm. Arrhythmia, heart rhythm and myocardial conduction disorders pose a significant danger to the life and health of the patient, as they can lead to severe disorders of central hemodynamics, the development of heart failure and circulatory arrest.

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What causes arrhythmia?

Some of the cardiac arrhythmias and conduction disturbances that occur are short-term and transient. For example, transient benign arrhythmia, mainly ventricular and supraventricular extrasystoles, is a common occurrence even in healthy people. Usually, such arrhythmia does not require treatment. Other disturbances (paroxysmal ventricular tachycardia, complete atrioventricular block) dramatically worsen the heart's hemodynamics and can quickly lead to circulatory arrest.

Arrhythmia, atrial fibrillation and flutter often occur when left atrial pressure increases due to left ventricular dysfunction. Their effect on hemodynamics largely depends on the ventricular rate.

Cardiac arrhythmia and conduction disturbances may occur as a result of various pathological conditions (myocardial infarction, heart defects, cardiosclerosis, vegetative-vascular dystonia, etc.). They are caused by changes in the main functions of the heart (automatism, excitability, conduction, etc.). Among the factors that largely determine the development of arrhythmia, the most significant are: uncontrolled pain syndrome, electrolyte imbalance, increased levels of catecholamines, angiotensin, metabolic acidosis, arterial hypo- and hypertension. These factors not only predispose to the development of arrhythmia, but also reduce the activity of antiarrhythmic drugs.

In the broad sense of the word, arrhythmia is any heart rhythm that is not a regular sinus rhythm of normal frequency.

Sinus rhythm is the heart rhythm originating from the sinus node (the first-order pacemaker) with a frequency of 60-80 impulses per minute. These impulses spread to the atria and ventricles, causing them to contract (their spread is recorded on the electrocardiogram as the usual P, QRS and T waves). An accurate diagnosis of arrhythmia of a patient's heart rhythm or conduction disorder can only be made on the basis of an electrocardiographic study.

Factors that provoke arrhythmia can be both external influences and internal diseases and disorders of the functioning of organ systems. Among the most typical causes are the following:

• Myocarditis is an inflammatory lesion of the heart muscle, usually of viral etiology;
• Cardiosclerosis is the proliferation of connective tissue and scarring of the heart muscle;
• Heart attack;
• Violation of the norms of magnesium, potassium, calcium content in the blood - electrolyte balance;
• Bacterial infection;
• Pulmonary pathologies, insufficient oxygen supply to the blood;
• Stress, neurotic conditions;
• Injuries, including head injuries;
• Menstrual irregularities, menopause;
• Adrenal diseases;
• Thyroid diseases;
• Hypertension, hypotension.

In fact, anything can provoke arrhythmia if the body is weakened and there are problems with the cardiovascular system.

How does arrhythmia manifest itself?

Arrhythmia is clinically divided into the following types:

Tachycardia (sinus)

The sinus node is the most important element of the myocardium, it is the one that ensures the formation of electrical impulse transmission. This is an excessively active contraction of the muscle, exceeding the required 90 beats per minute. Subjectively, such arrhythmia is felt as an increased heartbeat. Stress, intense, unusual physical activity can provoke tachycardia. Less often, tachycardia is caused by internal diseases.

Bradycardia (sinus)

The heart rate decreases, sometimes falling to 50 beats per minute. Bradycardia does not necessarily signal problems with the cardiovascular system; sometimes it can manifest itself in absolutely healthy people during complete relaxation or sleep. Bradycardia is also typical for hypotensive patients and those suffering from hypothyroidism. Subjective sensations can manifest themselves as weakness, a feeling of pressure in the heart area, and dizziness.

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Sinus arrhythmia

Typical for small children and children in puberty. Alternating heartbeats can be associated with the active growth of organs and systems, as well as with breathing. This type of arrhythmia does not require therapeutic intervention.

Extrasystole

This is an unplanned disruption of the rhythmic contraction of the muscle. The rhythm seems to be out of rhythm. This type of arrhythmia is provoked by an unhealthy lifestyle, smoking, and alcohol abuse. It is also often associated with an underlying somatic disease if the cause is eliminated, or goes into remission, or disappears. Subjectively, it manifests itself as sudden heartbeats or equally sudden heart stops.

Paroxysmal tachycardia

This is excessive activity of the heart, which beats rhythmically, but too quickly. The heart rate sometimes exceeds 200 beats per minute. It is often accompanied by vegetative reactions, sweating, dizziness, and reddening of the skin of the face.

Atrial fibrillation (AF)

This type of arrhythmia is provoked by cardiosclerosis, rheumatic heart disease, and thyroid disease. Often, atrial fibrillation is caused by a heart defect. Individual sections of the heart muscle begin to contract irregularly against the background of incomplete contraction of the atrium itself. The atria may seem to "flutter", subjective sensations are similar - fluttering, shortness of breath. The main clinical sign of atrial fibrillation is a pulse that noticeably lags behind the heart muscle contraction rate. According to prognostic values, this is the most dangerous arrhythmia, which can end in loss of consciousness, convulsions, and cardiac arrest.

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Block arrhythmia

Heart blocks are characterized by a complete loss of pulse. This happens because impulses stop being conducted through the myocardial structures in the right rhythm, sometimes this process slows down so much that the patient's pulse is almost undetectable. This is also a life-threatening arrhythmia, since in addition to convulsions and fainting, it can end in heart failure and even death.

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Periarest arrhythmia

Cardiac rhythm and myocardial conduction disturbances that occur in the periarrest period (i.e. before circulatory arrest and after its restoration) pose a significant danger to the patient's life (in English-language literature they are called periarrest arrhythmias). This arrhythmia can dramatically worsen central hemodynamics and quickly lead to circulatory arrest.

Cardiac arrhythmia and conduction disturbances can occur as a result of various pathological conditions, but they are based on changes in cardiac punctures such as automatism, excitability and conduction.

Among the factors that cause the development of arrhythmia, the most important are pain syndrome, ischemia, electrolyte imbalance, increased levels of catecholamines, angiotensin, metabolic acidosis, arterial hypo- and hypertension. These factors not only predispose to the development of arrhythmia, but also reduce the activity of antiarrhythmic drugs.

Pain, ischemia, and electrolyte imbalances are reversible causes of life-threatening tachyarrhythmias and define the risk group for potential arrhythmic events.

All arrhythmias preceding circulatory arrest and arrhythmia that occurs after restoration of spontaneous circulation require immediate intensive care to prevent cardiac arrest and stabilize hemodynamics after successful resuscitation.

The gradation of periarrest arrhythmia is based on the presence or absence of adverse signs and symptoms in the patient associated with cardiac arrhythmia and indicating instability of the condition. The main signs are listed below.

1. Clinical symptoms of decreased cardiac output. Signs of activation of the sympathoadrenal system: pale skin, increased sweating, cold and clammy extremities, increasing signs of impaired consciousness due to decreased cerebral blood flow, Morgagni-Adams-Stokes syndrome, arterial hypotension (systolic pressure less than 90 mm Hg).
2. Severe tachycardia. An excessively rapid heart rate (more than 150 per minute) reduces coronary blood flow and can cause myocardial ischemia.
3. Heart failure. Left ventricular failure is indicated by pulmonary edema, and increased pressure in the jugular veins (jugular venous distension) and liver enlargement indicate right ventricular failure.
4. Pain syndrome. The presence of chest pain means that arrhythmia, especially tachyarrhythmia, is caused by myocardial ischemia. The patient may or may not complain of increased heart rate.

Threatening arrhythmia

Threatening arrhythmia is a disturbance of the heart rhythm that immediately precedes and transforms into ventricular fibrillation and asystole. Long-term electrocardiographic monitoring has shown that ventricular fibrillation is most often preceded by paroxysms of ventricular tachycardia with a gradual increase in rhythm, turning into ventricular flutter. A dangerous type of ventricular tachycardia is "tachycardia of the vulnerable period", a characteristic feature of which is the onset of an early ventricular extrasystole.

The most dangerous are episodes of polytopic ventricular tachycardia, in particular, bidirectional spindle-shaped "pirouette" ventricular tachycardia (torsades de pointes - occurs quite rarely). This type of polymorphic, pause-dependent ventricular arrhythmia occurs under conditions of an extended QT interval. There are two main forms of this tachyarrhythmia: acquired arrhythmia (provoked by drugs) and congenital arrhythmia. Antiarrhythmic drugs in these forms can act as both causative and contributing agents of proarrhythmia. For example, torsades de pointes ventricular tachycardia can be provoked by drugs that increase the duration of the membrane action potential of cardiomyocytes (antiarrhythmic drugs of class IA, III and others). However, prolongation of the QT interval itself does not necessarily cause arrhythmia.

Among the factors influencing the development of torsades de pointes are:

• diuretic treatment;
• increased plasma concentrations of antiarrhythmic drugs (except quinidine);
• rapid intravenous administration of the drug;
• conversion of atrial fibrillation to sinus rhythm with the occurrence of a pause or bradycardia;
• prolongation of the QT interval, lability of the Gili wave or its morphological changes, increase in QT dispersion during therapy;
• congenital long QT syndrome.

Intracellular calcium overload can significantly increase the risk of torsades de pointes. Genetic abnormalities in the coding of transmembrane ion channels increase the risk of torsades de pointes by disrupting drug metabolism.

The use of cordarone, which promotes prolongation of the QT interval, does not lead to the development of torsades de pointes. In patients with hypokalemia, hypomagnesemia and bradycardia (especially in females), the heterogeneity of the drug effect of antiarrhythmic drugs at different levels of the myocardium increases. There is evidence that this heterogeneity can be reduced by blocking arrhythmogenic currents with cordarone.

Types of arrhythmia

There are a number of classifications of cardiac rhythm and conduction disorders. One of the most convenient, in our opinion, is the classification of V.N. Orlov [2004], which is based on electrocardiographic signs.

A. Arrhythmia caused by disturbances in the automatic function of the sinus node (sinus tachycardia and bradycardia, sinus arrhythmia, sinus node arrest, atrial asystole and sick sinus syndrome).

B. Ectopic rhythms.

I. Passive complexes or rhythms (atrial, atrioventricular, ventricular, etc.).

II. Active:

1. extrasystole (atrial, atrioventricular, ventricular);
2. parasystole;
3. paroxysmal and non-paroxysmal tachycardia (atrial, atrioventricular, ventricular).

B. Atrial and ventricular fibrillation, flutter.

G. Conduction disorders (sinoatrial block, intra-atrial block, atrioventricular block, intraventricular conduction disorders, bundle branch block and left bundle branch block).

For the convenience of practical work, V.V. Ruksin [2004] developed a classification of cardiac rhythm and conduction disorders depending on the required emergency care:

1. Arrhythmia requiring resuscitation measures (causing clinical death or Morgagni-Adams-Stokes syndrome).
2. Arrhythmia requiring intensive care (causing shock or pulmonary edema).
3. Arrhythmia requiring urgent treatment (causing disruption of systemic or regional blood circulation; threatening to develop into ventricular fibrillation or asystole; repeated paroxysms with a known method of suppression).
4. Arrhythmia that requires not only intensive monitoring, but also planned treatment (newly occurring arrhythmias without clinically significant disorders of systemic or regional circulation; arrhythmias in which the primary treatment is the underlying disease or condition).
5. Arrhythmia requiring correction of the ventricular rate (paroxysms of acceleration with a constant form of atrial fibrillation or flutter; arrhythmias that are poorly tolerated subjectively).

Of greatest interest in terms of emergency care are the first three groups of cardiac arrhythmias. These are ventricular fibrillation, ventricular paroxysmal tachyarrhythmias, paroxysms of atrial and supraventricular arrhythmias with pronounced disturbances of central hemodynamics.

How is arrhythmia recognized?

Arrhythmia is diagnosed according to the standard scheme:

• Collection of anamnesis;
• Inspection – appearance, skin;
• Pulse diagnostics;
• Electrocardiogram, and possibly daily electrocardiogram (Holter monitoring)
• Less commonly, an electrophysiological examination is performed (electrosensors are inserted into the heart).

How is arrhythmia treated?

Arrhythmia is treated depending on its type:

Tachycardia

As a rule, it does not require serious therapeutic measures and prescriptions. Rest, peace, giving up bad habits, mastering relaxation techniques, following a rational diet and a healthy lifestyle in principle - these are the main methods of treating tachycardia. As a symptomatic treatment, soothing herbal teas, valerian tincture (or in tablet form), and Corvalol are prescribed. In more serious cases, when rapid heartbeat is a consequence of pathological processes in the cardiovascular system, the doctor may prescribe drug therapy (verapamil, propranolol). It is also good to take drugs containing magnesium and potassium.

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Bradycardia

If bradycardia is rare and mild, symptomatic treatment is prescribed. In more serious situations, when bradycardia is caused by insufficient cardiac muscle function, atenolol, euphyllin, and atropine group of drugs are prescribed. If bradycardia threatens the patient's life, electrical cardiac stimulation is performed, including implantation.

Extrasystole

Symptomatic treatment consists of relaxing, calming drugs. Psychotherapy sessions and autogenic training are also indicated. Beta-blockers (atenolol, metoprolol, and others) are used to treat serious pathologies. Antiarrhythmic drugs are selected by a doctor; self-medication in case of diagnosis of this condition is unacceptable.

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Atrial fibrillation

Combination therapy is prescribed taking into account the anamnesis and results of diagnostic studies. Electrocardioversion is often used - the heart rhythm is restored using electrical discharges of a certain frequency externally, on the skin in the heart area. Cardioversion can also be internal, when electrodes are passed directly to the heart through the veins.

Arrhythmia often accompanies the life of many of us. The main thing is to find its true cause, eliminate the underlying disease if possible or transfer it to a form of stable remission. Then - compliance with preventive measures, a course of prescribed medications, then heart rhythm disturbances practically disappear and can only occur against the background of positive emotional stress, which is unlikely to harm health.

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