Antiarrhythmic drugs are used to eliminate or prevent heart rhythm disturbances of various etiologies. They are divided into drugs that eliminate tachyarrhythmias. and drugs effective for bradyarrhythmias.
Ventricular fibrillation followed by asystole is responsible for 60-85% of cases sudden death, especially cardiac patients. In many of them, the heart is still quite capable of contractile activity and could work long years. At least 75% of patients with myocardial infarction and 52% of patients with heart failure suffer from progressive disorders heart rate.
Chronic, recurrent forms of arrhythmias accompany heart diseases (valvular defects, myocarditis, coronary insufficiency, cardiosclerosis, hyperkinetic syndrome) or occur against the background of disorders of the neuroendocrine regulation of cardiac activity (thyrotoxicosis, pheochromocytoma). Arrhythmias develop during intoxication with nicotine, ethyl alcohol, cardiac glycosides, diuretics, caffeine, anesthesia with halogen-containing general anesthetics, operations on the heart, blood vessels, and lungs. Heart rhythm disturbances are often a vital indication for emergency treatment with antiarrhythmic drugs. In recent years, the paradoxical fact has been established that antiarrhythmic drugs can cause dangerous arrhythmias. This limits their use for arrhythmias with minimal clinical manifestations.
In 1749, it was proposed to take quinine for “persistent palpitations.” In 1912 to Karl Friedrich Wenckebach (1864-1940), a famous German cardiologist who described Wenckebach's block. A merchant contacted him about a heart attack. Wenckebach diagnosed atrial fibrillation, but explained to the patient that it was not possible to relieve it with medications. The merchant expressed doubts about the medical competence of cardiologists and decided to undergo treatment on his own. He took 1 g of quinine powder, which in those days had a reputation as a cure for all diseases. After 25 minutes, the heart rhythm returned to normal. Since 1918, the dextrorotatory isomer of quinine, quinidine, was introduced into medical practice on the recommendation of Wenckebach.
Under normal conditions, the function of the heart pacemaker is performed by the sinus node. His P-cells (the name is from the first letter of the English word racemaker) have automaticity - the ability to spontaneously. during diastole generate an action potential. The resting potential of β cells ranges from -50 to -70 mV, and depolarization is caused by incoming flows of calcium ions. The following phases are distinguished in the structure of the membrane potential of β-cells:
Phase 4 - slow spontaneous diastolic calcium-type depolarization; phase 0 - development of a positive action potential +20-30 mV after reaching the depolarization threshold in phase 4;
Phase 1 - rapid repolarization (input of chlorine ions);
Phase 2 - slow repolarization (output of potassium ions and slow influx of calcium ions);
Phase 3 - final repolarization with restoration of the negative resting potential.
During the resting potential, the ion channels are closed (the external activation and internal inactivation gates are closed), during depolarization the channels open (both types of gates are open), during the repolarization period the ion channels are in an inactivated state (the external gates are open, the internal gates are closed).
Action potentials from the β-cells of the sinus node propagate through the atrial conduction system, the atrioventricular node, and the intraventricular His-Purkinje fiber system (in the direction from the endocardium to the epicardium). In the conduction system of the heart, the cells are long and thin, contact each other in the longitudinal direction, and have rare lateral connections. Action potentials are conducted 2-3 times faster along cells than in the transverse direction. The speed of impulse conduction in the atria is -1 m/s, in the ventricles - 0.75-4 m/s.
ECG wave R corresponds to atrial depolarization, complex ORS - ventricular depolarization (phase 0), segment ST - repolarization phases 1 and 2, wave T - repolarization phase 3.
In the conduction system of a healthy heart, distal to the sinus node, spontaneous depolarization occurs much more slowly than in the sinus node, and therefore is not accompanied by an action potential. There is no spontaneous depolarization in the contractile myocardium. The cells of the conduction system and contractile myocardium are excited by impulses from the sinus node. In the atrioventricular node, spontaneous depolarization is caused by the entry of calcium and sodium ions, in the Purkinje fibers - the entry of only sodium ions (“sodium” potentials).
The rate of spontaneous depolarization (phase 4) is regulated by the autonomic nervous system. With increased sympathetic influences, the entry of calcium and sodium ions into cells increases, which accelerates spontaneous depolarization. With an increase in parasympathetic activity, potassium ions are released more intensely, slowing down spontaneous depolarization.
During an action potential, the myocardium is in a state of refractory to stimulation. With absolute refractoriness, the heart is not capable of excitation and contraction, regardless of the strength of stimulation (phase 0 and the beginning of repolarization); at the beginning of the relative refractory period, the heart is excited in response to a strong stimulus (the final stage of repolarization); at the end of the relative refractory period, the excitation is accompanied by contraction.
The effective refractory period (ERP) covers the absolute refractory period and the initial part of the relative refractory period, when the heart is capable of weak excitation, but does not contract. On the ECG, the ERP corresponds to the complex QRS and the ST segment.
PATHOGENESIS OF ARRHYTHMIAS
Tachyarrhythmias arise due to disturbances in impulse formation or circulation of a circular excitation wave.
Impulse formation disorder
In patients with arrhythmia, heterotopic and ectopic pacemakers appear in the myocardium, which have greater automatism than the sinus node.
Heterotopic foci are formed in the conduction system distal to the sinus node.
Ectopic lesions appear in the contractile myocardium.
Impulses from additional foci cause tachycardia and extraordinary contractions of the heart.
A number of factors contribute to the “unleashing” of abnormal automatism:
The occurrence or acceleration of spontaneous depolarization (the entry of calcium and sodium ions is facilitated under the influence of catecholamines, hypokalemia, stretching of the heart muscle);
Reducing the negative diastolic resting potential (myocardial cells contain excess calcium and sodium ions during hypoxia, blockade Na/TO-ATPase and calcium-dependent ATPase);
Reduction of ERP (potassium and calcium conductivity increases in phase 2. development of the next action potential is accelerated);
Weakness of the sinus node with rare generation of impulses;
Release of the conduction system from the control of the sinus node during conduction block (myocarditis, cardiosclerosis).
Trigger activity is manifested by early or late trace depolarization. Early trace depolarization, interrupting phases 2 or 3 of the transmembrane potential, occurs with bradycardia, low content of potassium and magnesium ions in the extracellular fluid, and excitation of beta-adrenergic receptors. It causes polymorphic ventricular tachycardia (torsades de pointes). Late trace depolarization develops immediately after the end of repolarization. This type of trigger activity is caused by overload of myocardial cells with calcium ions during tachycardia, myocardial ischemia, stress, and poisoning with cardiac glycosides.
Circular wave of excitation
Excitation wave circulation reentry - repeated admission) contributes to heterochronism - a mismatch in the time of the refractory period of myocardial cells. A circular excitation wave encountering refractory depolarized tissue in the main conduction path. is sent along an additional path. but can return in the antidromic direction along the main path. if the refractory period has ended. Pathways for the circulation of excitation are created in the border zone between scar tissue and intact myocardium. The main circular wave breaks up into secondary waves that excite the myocardium, regardless of impulses from the sinus node. The number of extraordinary contractions depends on the period of wave circulation before attenuation.
CLASSIFICATION OF ANTIARRYTHMIC DRUGS
Antiarrhythmic drugs are classified according to their effect on the electrophysiological properties of the myocardium (E.M. Vaughan Williams, 1984; D.C. Hamson. 1985) (Table 38.2).
Whether there is an arrhythmia, where and why it occurred, whether it should be treated can only be determined by a cardiologist. In diversity antiarrhythmic drugs Only a specialist can figure it out. The use of many drugs is indicated for narrow pathologies and has a lot of contraindications. Therefore, drugs from this list should not be prescribed to oneself.
Disturbances that cause everything known species arrhythmias, mass. They are not always directly related to heart pathology. But reflected in the work of this important body, can cause acute and chronic heart rhythm pathologies that are life-threatening.
General picture of arrhythmia
The heart performs its work under the influence of electrical impulses. The signal is born in the main center that controls contractions - the sinus node. Next, the impulse is transported to both atria along conduction tracts and bundles. The signal, entering the next atrioventricular node, spreads through the His bundle to the right and left atrium along nerve endings and groups of fibers.
Coordinated work of all parts of this complex mechanism, ensures a rhythmic beating of the heart with normal frequency(from 60 to 100 beats per minute). A violation in any area causes a failure and disrupts the frequency of contractions. Moreover, violations may be different order: irregular functioning of the sinuses, inability of muscles to carry out orders, disruption of the conduction of nerve bundles.
Any obstacle in the way of the signal or its weakness also leads to the fact that the transmission of the command will follow a completely different scenario, which provokes chaotic, irregular contractions of the heart.
The reasons for some of these violations have not yet been fully established. Like the mechanism of action of many drugs that help restore the usual rhythm, it is not completely clear. However, effective drugs Many have been developed for the treatment and immediate relief of arrhythmia. With their help, most violations are successfully eliminated or can be corrected over a long period of time.
Classification of antiarrhythmic drugs
An electrical impulse is transmitted due to the constant movement of positively charged particles - ions. The heart rate (HR) is affected by the penetration of sodium, potassium, and calcium ions into the cells. By preventing them from passing through special channels in cell membranes, the signal itself can be affected.
Medicines for arrhythmia are grouped not according to active substance, but by the effect produced on the conduction system of the heart. Substances with completely different chemical composition. According to this principle, antiarrhythmic drugs (AAP) were classified by Vaughan Williams in the 60s of the 20th century.
The simplest classification according to Williams, distinguishes 4 main classes of AAP and is generally applicable to this day.
Traditional classification of antiarrhythmic drugs:
- Class I – block sodium ions;
- Class II – beta-blockers;
- Class III – blocks potassium particles;
- Class IV – calcium antagonists;
- Class V is conditional and includes all antiarrhythmic drugs that are not included in the classification.
Even with subsequent modifications, such a division is not considered ideal. But attempts to propose a distinction between antiarrhythmic drugs based on other principles have not yet been successful. Let's look at each class and subclass of AAP in more detail.
Blockers Na- channels (1 class)
The mechanism of action of class 1 drugs is based on the ability of some substances to block sodium channels and slow down the speed of propagation of electrical impulses throughout the myocardium. The electrical signal in arrhythmic disorders often moves in a circle, causing additional contractions of the heart muscle that are not controlled by the main sinus. Blocking sodium ions helps correct precisely such violations.
Class 1 is the largest group of antiarrhythmic drugs, which is divided into 3 subclasses: 1A, 1B and 1C. They all have a similar effect on the heart, reducing the number of its contractions per minute, but each has some features.
1A – description, list
In addition to sodium, drugs block potassium channels. In addition to good antiarrhythmic properties, they additionally have a local anesthetic effect, since blocking the channels of the same name in the nervous system leads to a strong anesthetic effect. List of commonly prescribed drugs of group 1A:
- Novocainamide;
- Quinidine;
- Aymalin;
- Gilurithmal;
- Disopyramide.
The drugs are effective in relieving multiple acute conditions: extrasystole (ventricular and supraventricular), atrial fibrillation and its paroxysms, some tachycardias, including with WPW (premature ventricular excitation).
Novocainamide and quinidine are used more often than other drugs in the group. Both drugs are available in tablet form. They are used for the same indications: supraventricular tachycardia, atrial fibrillation with a tendency to paroxysms. But drugs have various contraindications and possible negative consequences.
Due to severe toxicity and many non-cardiological side effects, class 1A is primarily used to relieve an attack; for long-term therapy it is prescribed when it is impossible to use medications from other groups.
Attention! Arrhythmogenic effects of AAP! When treated with antiarrhythmic drugs, in 10% of cases (for 1C - in 20%), the opposite effect to the intended one occurs. Instead of stopping the attack or reducing the heart rate, the initial condition may worsen and fibrillation may occur. Arrhythmogenic effects represent real threat for life. Taking any type of AAP must be prescribed by a cardiologist and must be carried out under his supervision.
1B – properties, list
They differ in the property that they do not inhibit, like 1A, but activate potassium channels. They are used mainly for ventricular pathologies: tachycardia, extrasystole, paroxysm. Most often, they require a jet or drip intravenous administration. IN Lately, many class 1B antiarrhythmic drugs are available in tablet form (for example, Difenin). The subgroup includes:
- Lidocaine;
- Difenin;
- Mexiletine;
- Pyromecaine;
- Trimecaine;
- Phenytoin;
- Aprindin.
The properties of medications in this group make it possible to use them even during myocardial infarction. The main side effects are associated with significant depression nervous system, there are practically no cardiac complications.
Lidocaine is the most famous medicinal product from the list, is famous for its excellent anesthetic properties, which are used in all branches of medicine. It is characteristic that the effectiveness of the drug taken orally is practically not observed; it is with intravenous infusion that lidocaine has the strongest antiarrhythmic effect. The most effective jet injection is rapid. Often causes allergic reactions.
1C – list and contraindications
The most powerful blockers of sodium and calcium ions, act at all levels of signal transmission, starting with sinus node. They are used mainly internally. Medicines from the group differ wide range applications, exhibit high efficiency in atrial fibrillation, with tachycardia of various origins. Frequently used means:
- Propafenone;
- Flecainide;
- Indecainide;
- Ethacizin;
- Ethmozin;
- Lorcainide.
They are used for both rapid relief and permanent treatment of supraventricular and ventricular arrhythmias. Medicines from this group are not applicable for any organic heart damage.
Propaferon (rhythmonorm) has only recently become available in intravenous form. It has a membrane-stabilizing effect, exhibits beta-blocker properties, and is used for paroxysmal rhythm disturbances (extrasystole, atrial fibrillation and flutter), WPW syndrome, atrial ventricular tachycardia, as a preventive measure.
The entire 1st class has limitations in use in cases of organic damage to the myocardium, serious heart failure, scars, and other pathological changes in heart tissue. After conducting statistical studies, an increase in the mortality rate of patients with similar diseases was found when treated with this class of AAP.
Antiarrhythmic drugs latest generation, often called beta blockers, compare favorably in these indicators with class 1 antiarrhythmics and are increasingly used in practice. The introduction of these drugs into the course of treatment significantly reduces the likelihood of an arrhythmogenic effect of medications from other groups.
Beta blockers – class II
Block adrenergic receptors, slow heart rate. Monitor contractions during atrial fibrillation, fibrillation, and some tachycardias. They help avoid the influence of stressful conditions by blocking the ability of catecholamines (in particular adrenaline) to act on andrenoreceptors and cause increased heart rate.
After a heart attack, the use of beta blockers significantly reduces the risk of sudden death. Well proven in the treatment of arrhythmias:
- Propranolol;
- Metoprolol;
- Cordanum;
- Acebutalol;
- Trazikor;
- Nadolol.
Long-term use can cause sexual dysfunction, bronchopulmonary disorders, and increased blood sugar. β-blockers are absolutely contraindicated in certain conditions: acute and chronic forms heart failure, bradycardia, hypotension.
Important! Beta blockers cause withdrawal syndrome, so it is not recommended to stop taking them abruptly - only according to the regimen, for two weeks. It is not advisable to skip taking pills or take breaks from treatment without permission.
Significant depression of the central nervous system is observed with long-term use: memory deteriorates, depressive states, noted general weakness and laxity of the musculoskeletal system.
Blockers TO- channels – III class
They block charged potassium atoms at the entrance to the cell. Heart rhythms, unlike class 1 drugs, slow down slightly, but are able to stop long-term, months-long atrial fibrillation, where other drugs are powerless. Comparable in action to electrocardioversion (restoration of heart rhythm using an electrical discharge).
Arrhythmic side effects are less than 1%, however, a large number of non-cardiac side effects, require constant medical monitoring during treatment.
List of commonly used products:
- Amiodarone;
- Bretylium;
- Sotalol;
- Ibutilide;
- Refralol;
The most commonly used drug on the list is amiodarone (cordarone), which exhibits the properties of all classes of antiarrhythmic drugs and is additionally an antioxidant.
Note!Cordarone can be called the most effective antiarrhythmic drug today. Like beta blockers, it is the first choice drug for arrhythmic disorders of any complexity.
The latest generation class III antiarrhythmic drugs include dofetilide, ibutilide, and nibentan. They are used for atrial fibrillation, but the risk of tachycardia of the “pirouette” type increases significantly.
The peculiarity of only class 3 is the ability to cause severe forms of tachycardia when taken together with cardiological and other arrhythmic drugs, antibiotics (macrolides), antihistamines, and diuretics. Cardiac complications in such combinations can cause sudden death syndrome.
Calcium blockers class IV
By reducing the flow of charged calcium particles into cells, they act on both the heart and blood vessels, and affect the automaticity of the sinus node. By reducing myocardial contractions, they simultaneously dilate blood vessels, lower blood pressure, and prevent the formation of blood clots.
- Verapamil;
- Dilthiozel;
- Nifedipine;
- Diltiazem.
Class 4 drugs allow you to correct arrhythmic disorders in hypertension, angina, and myocardial infarction. Should be used with caution in atrial fibrillation with SVC syndrome. Cardiac side effects include hypotension, bradycardia, circulatory failure (especially in combination with β-blockers).
Antiarrhythmic drugs of the latest generation, the mechanism of action of which is blocking calcium channels, have a prolonged effect, which allows you to take them 1-2 times a day.
Other antiarrhythmic drugs – class V
Medicines that have a positive effect on arrhythmias, but do not fall into the Williams classification according to their mechanism of action, are combined into the conditional 5th group of drugs.
Cardiac glycosides
The mechanism of action of the drugs is based on the properties of natural heart poisons to have a positive effect on the cardiovascular system, subject to the correct dosage. By reducing the number of heart contractions, they simultaneously increase their efficiency.
Plant poisons are used for immediate relief of tachycardia and are applicable in long-term treatment of rhythm disturbances due to chronic heart failure. They slow down the conduction of nodes and are often used to correct atrial flutter and fibrillation. Can replace beta-blockers if their use is contraindicated.
List of plant glycosides:
- Digoxin.
- Strophanin;
- Ivabradine;
- Korglykon;
- Atropine.
An overdose can cause tachycardia, atrial fibrillation and lead to ventricular fibrillation. With prolonged use, they accumulate in the body, causing specific intoxication.
Sodium, potassium, magnesium salts
Replenishes the deficiency vitally important minerals. They change the balance of electrolytes, allow you to relieve oversaturation with other ions (in particular calcium), lower blood pressure, and calm uncomplicated tachycardia. They show good results in the treatment of glycoside intoxications and the prevention of arrhythmogenic effects characteristic of classes 1 and 3 of AAP. The following forms are used:
- Magnesium sulfate.
- Sodium chloride.
- Potassium chloride.
Appointed to various forms for the prevention of many heart disorders. The most popular pharmaceutical forms of salts: Magnesium-B6, Magnerot, Orocomag, Panangin, Asparkam, Potassium and magnesium aspartate. On the recommendation of a doctor, a course of drugs from the list or vitamins may be prescribed mineral supplements for recovery after exacerbations.
Adenazine (ATP)
Urgent administration of adenosine triphosphate intravenously stops most attacks of sudden paroxysm. Due to the short period of action, in emergency cases it can be used several times in a row.
As a universal source of “fast” energy, it provides supportive therapy for a whole range of cardiac pathologies and is widely used for their prevention. Not prescribed together with cardiac glycosides and mineral supplements.
Ephedrine, isadrine
In contrast to beta blockers, the substances increase the sensitivity of receptors and stimulate the nervous and cardiovascular systems. This property is used to correct the contraction frequency during bradycardia. Long-term use is not recommended; they are used as emergency medications.
Prescribing classical antiarrhythmic drugs is complicated by the limited ability to predict their effectiveness and safety for each individual patient. This often leads to the need to search the best option selection method. Accumulation negative factors requires constant monitoring and examinations during treatment.
Latest generation antiarrhythmic drugs
In the development of a new generation of drugs for arrhythmia promising directions are the search for drugs with bradycardic properties, the development of atrial-selective drugs. Several new antiarrhythmics that can help treat ischemic disorders and the arrhythmias caused by them are in clinical trials.
Modification of known effective antiarrhythmic drugs (for example, Amiodarone and Carvedilol) is being carried out in order to reduce their toxicity and mutual influence with other cardiac drugs. The properties of drugs that were not previously considered as antiarrhythmics are being studied; this group also includes fish fat and ACE inhibitors.
The goal of developing new drugs for arrhythmia is to produce affordable drugs with the lowest cost. side effects, and ensuring a longer duration of their action, compared to existing ones, for the possibility of a single daily dose.
The above classification is simplified; the list of drugs is very large and is updated all the time. The purpose of each of them has its own reasons, characteristics and consequences for the body. Know them and prevent or correct them possible deviations Only a cardiologist can. Arrhythmia, complicated serious pathologies, cannot be treated at home, prescribing treatment and medications on your own is a very dangerous activity.
Antiarrhythmic drugs – medicines, used to normalize the heart rate. These chemical compounds belong to various pharmacological classes and groups. They are designed to treat and prevent their occurrence. Antiarrhythmics do not increase life expectancy, but are used to control clinical symptoms.
Antiarrhythmic drugs are prescribed by cardiologists if the patient has arrhythmia. pathological nature, which worsens the quality of life and can lead to the development severe complications. Antiarrhythmic drugs have a positive effect on the human body. They should be taken for a long time and only under the control of electrocardiography, which is carried out at least once every three weeks.
The cell wall of cardiomyocytes is penetrated by a large number of ion channels through which potassium, sodium, and chlorine ions move. Such movement of charged particles leads to the formation of an action potential. Arrhythmia is caused by abnormal propagation nerve impulses. To restore the heart rhythm, it is necessary to reduce activity and stop the circulation of the impulse. Under the influence of antiarrhythmic drugs, ion channels close and the pathological effect on the heart muscle decreases sympathetic division nervous system.
The choice of antiarrhythmic drug is determined by the type of arrhythmia, the presence or absence of structural heart pathology. If the necessary safety conditions are met, these drugs improve the quality of life of patients.
Antiarrhythmic therapy is primarily carried out for the purpose of recovery sinus rhythm. Patients are treated in a cardiology hospital, where they are given antiarrhythmic drugs intravenously or orally. In the absence of a positive therapeutic effect, move on to. Patients without concomitant chronic pathology hearts can restore sinus rhythm on their own in outpatient setting. If attacks of arrhythmia occur rarely, are short and have few symptoms, patients are indicated for dynamic observation.
Classification
The standard classification of antiarrhythmic drugs is based on their ability to affect the production of electrical signals in cardiomyocytes and their conduction. They are divided into four main classes, each of which has its own route of action. The effectiveness of medications for different types of arrhythmia will vary.
- Membrane-stabilizing sodium channel blockers - Quinidine, Lidocaine, Flecainide. Membrane stabilizers affect the functionality of the myocardium.
- – “Propranolol”, “Metaprolol”, “Bisoprolol”. They reduce mortality from acute coronary insufficiency and prevent relapses of tachyarrhythmias. Medicines in this group coordinate the innervation of the heart muscle.
- Potassium channel blockers - Amiodarone, Sotalol, Ibutilide.
- - “Verapamil”, “Diltiazem”.
- Others: sedatives, tranquilizers, neurotropic drugs have a combined effect on myocardial function and its innervation.
Table: division of antiarrhythmics into classes
Representatives of the main groups and their actions
1A class
The most common drug from the group of class 1A antiarrhythmics is “ Quinidine", which is made from the bark of the cinchona tree.
This medicine blocks the penetration of sodium ions into cardiomyocytes, reduces the tone of arteries and veins, has an irritating, analgesic and antipyretic effect, and inhibits brain activity. "Quinidine" has pronounced antiarrhythmic activity. It is effective when various types arrhythmias, but causes side effects if dosed and used incorrectly. Quinidine has an effect on the central nervous system, blood vessels and smooth muscles.
When taking the drug, it should not be chewed to avoid irritation of the gastrointestinal mucosa. For a better protective effect, it is recommended to take Quinidine with food.
effect of drugs of various classes on the ECG
1B class
Antiarrhythmic class 1B – "Lidocaine". It has antiarrhythmic activity due to its ability to increase membrane permeability to potassium and block sodium channels. Only significant doses of the drug can affect the contractility and conductivity of the heart. The medicine stops attacks of ventricular tachycardia in the post-infarction and early postoperative period.
To stop an arrhythmic attack, it is necessary to administer 200 mg of Lidocaine intramuscularly. If there is no positive therapeutic effect, the injection is repeated three hours later. IN severe cases the medicine is administered intravenously as a bolus, and then proceeds to intramuscular injections.
1C class
Class 1C antiarrhythmics prolong intracardiac conduction, but have a pronounced arrhythmogenic effect, which currently limits their use.
The most common remedy in this subgroup is "Ritmonorm" or "Propaphenone". This medicine is intended to treat extrasystole, a special form of arrhythmia caused by premature contraction heart muscle. "Propafenone" is an antiarrhythmic drug with a direct membrane-stabilizing effect on the myocardium and a local anesthetic effect. It slows down the influx of sodium ions into cardiomyocytes and reduces their excitability. "Propafenone" is prescribed to persons suffering from atrial and ventricular arrhythmias.
2nd grade
Class 2 antiarrhythmics - beta-blockers. Influenced "Propranolol" blood vessels dilate, blood pressure decreases, bronchial tone increases. In patients, the heart rate normalizes, even in the presence of resistance to cardiac glycosides. In this case, the tachyarrhythmic form is transformed into bradyarrhythmic, palpitations and interruptions in cardiac function disappear. The drug can accumulate in tissues, that is, there is a cumulation effect. Because of this, when using it in old age, doses must be reduced.
3rd grade
Class 3 antiarrhythmics are potassium channel blockers that slow down electrical processes in cardiomyocytes. The most prominent representative of this group is "Amiodarone". It dilates coronary vessels, blocks adrenergic receptors, and lowers blood pressure. The drug prevents the development of myocardial hypoxia, reduces the tone of coronary arteries, and reduces heart rate. The dosage for administration is selected only by the doctor on an individual basis. Because of toxic effect drug, its use must be constantly accompanied by monitoring of blood pressure and other clinical and laboratory parameters.
4th grade
Antiarrhythmic class 4 – "Verapamil". This is a highly effective remedy that improves the condition of patients with severe forms of angina, hypertension and arrhythmia. Under the influence of the drug, coronary vessels dilate, coronary blood flow increases, myocardial resistance to hypoxia increases, and the rheological properties of blood are normalized. "Verapamil" accumulates in the body and is then excreted by the kidneys. It is produced in the form of tablets, dragees and injections for intravenous administration. The medicine has few contraindications and is well tolerated by patients.
Other drugs with antiarrhythmic effects
Currently, there are many drugs that have an antiarrhythmic effect, but are not included in this pharmaceutical group. These include:
- Anticholinergics, which are used to increase heart rate during bradycardia - "Atropine".
- Cardiac glycosides intended to slow heart rate - "Digoxin", "Strophanthin".
- "Magnesium sulfate" used to stop an attack of a special ventricular tachycardia called “pirouette”. It occurs when there are severe electrolyte disturbances, as a result long-term use some antiarrhythmic drugs, after a liquid protein diet.
Antiarrhythmic drugs of plant origin
Medicines of plant origin have an antiarrhythmic effect. List of modern and most common drugs:
Side effects
The negative consequences of antiarrhythmic therapy are represented by the following effects:
Cardiovascular diseases - common reason death, especially among mature and elderly people. Heart disease triggers the development of other life-threatening conditions such as arrhythmia. This is a fairly serious health condition that does not allow self-treatment. At the slightest suspicion of development of this disease it is necessary to seek medical help, undergo a full examination and a full course of antiarrhythmic treatment under the supervision of a specialist.
Heart arythmy is a heart rhythm disorder: a disturbance in the normal sequence or frequency of heartbeats.
Heart rhythm disturbances are an independent and important section in cardiology. Occurring under various cardiovascular diseases(Ischemic heart disease, myocarditis, myocardial dystrophy and myocardiopathy), arrhythmias often cause heart and circulatory failure, aggravating the work and life prognosis. Treatment of arrhythmias requires strict individualization.
It can be considered generally accepted that arrhythmias arise mainly as a result of two processes - a disturbance in the formation or a disturbance in the conduction of an impulse (or a combination of both processes). In accordance with this, they are divided into groups.
Classification of cardiac arrhythmias:
I. Cardiac arrhythmias caused by impaired impulse formation:
– A. Automatic disorders:
1. Changes in the automaticity of the sinus node (sinus tachycardia, sinus bradycardia, sinus node arrest).
2. Ectopic rhythms or impulses caused by the predominance of automatism of the underlying centers.
– B. Other (besides automatism) mechanisms for disrupting the formation of impulses (extrasystoles, paroxysmal tachycardias).
II. Cardiac arrhythmias caused by impaired impulse conduction:
This different types blockade, as well as rhythm disturbances caused by the phenomenon of semi-blockade with return of excitation (re entry phenomenon).
III. Cardiac arrhythmias caused by combined disturbances in the formation and conduction of impulses.
IV. Fibrillation (atrial, ventricular).
Heart rhythm disturbances have an adverse effect on the body as a whole and primarily on the cardiovascular system. Cardiac arrhythmias can be a clinical manifestation, sometimes the earliest, coronary disease hearts, inflammatory diseases myocardium, extracardiac pathology. The appearance of arrhythmia requires examination of the patient to determine the causes of the arrhythmia.
Rhythm disturbances often lead to the appearance or worsening of circulatory failure, a drop in blood pressure up to arrhythmic collapse (shock). Finally, individual species ventricular arrhythmias may herald the onset of sudden death from ventricular fibrillation; these include ventricular paroxysmal tachycardia, ventricular extrasystole (polytopic, group, paired, early).
Treatment of cardiac arrhythmias:
When treating cardiac arrhythmias, etiological and pathogenetic therapy. However, its importance should not be overestimated, especially in urgent cases. The lack of a reliable antiarrhythmic effect in most cases of such therapy dictates the need for the use of special antiarrhythmic drugs.
Drugs used to treat cardiac arrhythmias:
Antiarrhythmic drugs exert their effect mainly by changing the permeability of the cell membrane and the ionic composition of the myocardial cell.
According to the main electrophysiological mechanisms of the occurrence of cardiac arrhythmias, antiarrhythmic drugs can have therapeutic effect if they have following properties:
a) the ability to have a suppressive effect on increased (pathological) automatism by reducing the slope of the diastolic (spontaneous) depolarization curve in phase 4;
b) the ability to increase the value of the resting transmembrane potential;
c) the ability to lengthen the action potential and the effective refractory period.
The main antiarrhythmic drugs can be divided into three classes:
I class. Membrane stabilizing agents:
Their action is based on the ability to inhibit the passage of electrolytes through a semi-permeable cell membrane, leading primarily to a slowdown in the entry of sodium ions during the depolarization period and the release of potassium ions during the repolarization period. Depending on the effect on the conduction system of the heart, drugs of this class can be divided into two subgroups (A and B).
– A. A group of drugs that have an inhibitory effect on myocardial conductivity (quinidine, novocainamide, ajmaline, etmozin, disopyramide).
Quinidine has the most pronounced inhibitory effect on automatism, excitability, conductivity and contractility; is one of the most antiarrhythmic drugs. However, due to the presence of significant side effects, its use is currently limited. Quinidine is prescribed mainly to restore sinus rhythm in cases of persistent atrial fibrillation, prolonged attacks of atrial fibrillation, and for prophylaxis in patients with frequent attacks atrial fibrillation (flutter).
Quinidine sulfate (Chinidinum sulfas) is usually prescribed orally to restore sinus rhythm in atrial fibrillation. There are various schemes for using the drug. Old regimens involved the administration of quinidine 0.2-0.3 g every 2-4 hours (except at night) with a gradual increase in dose to the maximum over 3-7 days. Daily dose should not exceed 2 g, in some cases maximum dose equal to 3 g. Currently, treatment is often started with a loading dose of 0.4 g, followed by 0.2 g of quinidine every 2 hours. In subsequent days, the dose is gradually increased. After restoration of sinus rhythm, maintenance doses are 0.4–1.2 g/day for a long period under regular electrocardiographic monitoring. For atrial extrasystole, 0.2-0.3 g of quinidine is prescribed 3-4 times a day, for attacks of ventricular tachycardia - 0.4-0.6 g every 2-3 hours.
Quinidine bisulfate is used at a dose of 0.25 g 2 times a day (1-2 tablets), to restore sinus rhythm, you can give 6 tablets a day.
Aymalin (gilurythmal, tahmalin) is an alkaloid found in the roots of the Indian plant Rauwolfia serpentina (Snake Rauwolfia). Used for the prevention and treatment of atrial and ventricular extrasystole. At intravenous administration ajmaline gives good effect with paroxysms of tachyarrhythmia. It is also used for Wolff-Parkinson-White syndrome. The drug is available in tablets of 0.05 g and in ampoules of 2 ml of 2.5% solution. Aymalin is prescribed intramuscularly, intravenously and orally. Initially, up to 300–500 mg/day is used orally in 3–4 doses, with maintenance doses of 150–300 mg/day. Usually 50 mg (2 ml of a 2.5% solution) is administered intravenously in 10 ml of a 5% glucose solution or isotonic sodium chloride solution slowly over 3–5 minutes. 50–150 mg/day is administered intramuscularly.
– B. A group of membrane-stabilizing drugs that do not have a significant effect on myocardial conductivity (lidocaine, trimecaine, mexitil, diphenine).
Unlike quinidine, they somewhat shorten (or do not lengthen) the refractory period, due to which myocardial conductivity is not impaired, and according to some data, it is improved.
Lidocaine (Lidocaini) is one of the most effective and most safe means for the relief of ventricular paroxysmal tachycardias, prognostically unfavorable ventricular extrasystoles.
II class. Antiadrenergic drugs:
– A. Blockers of β-adrenergic receptors (anaprilin, oxprenolol, amiodarone, etc.).
The antiarrhythmic effect of drugs in this group consists of their direct antiadrenergic effect, as well as the quinidine-like effect exerted by most drugs in this group. Beta blockers are indicated in the treatment of extrasystole (atrial and ventricular), in the form course treatment with paroxysms of atrial fibrillation and flutter, supraventricular and ventricular tachycardia, as well as persistent sinus tachycardia (not associated with heart failure).
Beta blockers are contraindicated in cases of severe circulatory failure, atrioventricular block I–III degree, bronchial asthma. Caution is required when treating extrasystole, paroxysmal atrial fibrillation due to sick sinus syndrome, as well as diabetes mellitus.
III class. Calcium antagonists:
The antiarrhythmic effect of drugs in this group is explained mainly by inhibition of calcium entry and potassium exit from myocardial cells. The most effective and widely used is verapamil. When administered intravenously, verapamil (isoptin) stops attacks of supraventricular paroxysmal tachycardia; effective for atrial fibrillation and flutter. Orally prescribed for the prevention of extrasystoles (usually atrial), paroxysms of atrial fibrillation.
Potassium supplements give positive result mainly for arrhythmias caused by digitalis intoxication, as well as in cases accompanied by significant hypokalemia, hypokaligistia.
Cardiac glycosides may have an antiarrhythmic effect. They are used mainly for rhythm disturbances (extrasystoles, paroxysms of atrial fibrillation) associated with obvious or hidden heart failure. Sometimes cardiac glycosides are combined with quinidine to prevent the negative inotropic effect of quinidine.
Heart rhythm disturbances caused by a slowdown in the conduction of impulses through the conduction system pose a serious therapeutic problem. This occurs with sinoatrial block, atrioventricular block, and Adams-Stokes-Morgagni syndrome.
Herbal medicine for cardiac arrhythmias:
Among herbal medicines for cardiac arrhythmias, ephedrine hydrochloride (Ephedrinum hydrochloridum) is used orally or subcutaneously in a single dose of 0.025–0.05 g. Higher single dose inside and under the skin 0.05 g, daily dose – 0.15 g. The drug is produced in tablets of 0.025 g and in ampoules of 1 ml of 5% solution.
Atropine sulfate (Atropinum sulfatis) is most often used intravenously or subcutaneously at a dose of 0.25–0.5 mg. Available in tablets of 0.0005 g and in ampoules of 1 ml of 0.1% solution.
Caffeine-sodium benzoate (Coffeinum-natrii benzoas) is prescribed in a single dose of 0.05 to 0.2 g 2-4 times a day. Available in tablets of 0.1–0.2 g and in ampoules of 1 and 2 ml of 10% and 20% solution.
Auxiliary in the treatment of atrial fibrillation and paroxysmal tachycardia with antiarrhythmic drugs, hawthorn fruits are used (Fruct. Crataegi). Assign liquid extract(Extr. Crataegi fluidum) 20-30 drops 3-4 times a day before meals or tincture (T-rae Crataegi) 20 drops 3 times a day.
For extrasystolic arrhythmia associated with functional neurotic reactions, the following mixture is indicated: T-rae Valerianae, T-rae Convallariae aa 10.0, Extr. Crataegi fluidi 5.0, Mentholi 0.05. Take 20–25 drops 2–3 times a day.
It is necessary to normalize sleep, its depth and duration. For this purpose, the following fees are recommended:
1. Three-leaf leaves (Fol. Trifolii fibrini 30.0), peppermint leaves (Fol. Menthae piperitae 30.0), valerian root (Rad. Valerianae 30.0). The infusion is prepared at the rate of 1 tablespoon per glass of boiling water. Take 1 glass of infusion 30–40 minutes before bedtime.
2. Buckthorn bark (Cort. Frangulae 40.0), chamomile flowers (Flor. Chamomillae 40.0). The infusion is prepared at the rate of 1 tablespoon of the mixture per glass of boiling water. In the evening, drink 1-2 glasses of infusion.
3. Three-leaf leaves (Fol. Trifolii fibrini 20.0), peppermint leaves (Fol. Menthae piperitae 20.0), angelica root (Rad. Archange 30.0), valerian root (Rad. Valerianae 30.0). The infusion is taken 1/3 cup 3 times a day.
4. Chamomile flowers (Flor. Chamomillae 25.0), peppermint leaves (Fol. Menthae piperitae 25.0), fennel fruits (Fruct. Foeniculi 25.0), valerian root (Rad. Valerianae 25.0), fruits caraway (Rad. Carvi 25.0). The decoction is taken in the evening, 1 glass.
Antiarrhythmic drugs are drugs used to treat irregular heartbeats. The pacemaker of the heart is the sinus node, where impulses are generated (originate).
However, the sinus node's ability to automatically produce impulses and cause rhythmic contractions of the heart may be impaired. This is possible with certain heart diseases (myocarditis), poisoning (cardiac glycosides), and dysfunction of the autonomic nervous system. Heart rhythm disturbances are also possible with various blockades of its conduction system.
Antiarrhythmic drugs are effective for various forms of cardiac arrhythmias, but due to the fact that they have different effects on the conduction system of the heart and its parts, they are divided into several groups, among which the leading ones are:
1) membrane stabilizing agents;
2) p-blocking agents (atenolol);
3) drugs that slow down repolarization (amiodarone);
4) blockers (antagonists) of calcium channels (verapamil).
Drugs of the first group due to some of their features
actions are further divided into three subgroups:
1 A - quinidine, novocainamide, rhythmylene;
1 B - local anesthetics or sodium channel blockers (lidocaine, trimecaine);
1 C - ajmaline, etacizin, allapinin.
In the mechanism of action of all antiarrhythmic drugs, the main role is played by their effect on cell membranes, the transport of sodium, potassium and calcium ions through them. Thus, drugs of subgroups 1 A and 1 C mainly suppress the transport of sodium ions through fast sodium channels of the cell membrane. Subgroup 1B drugs increase the permeability of membranes to potassium ions.
So, drugs of the first group reduce the rate of depolarization, slow down the conduction of impulses along the His bundle and Purkinje fibers, and slow down the restoration of the reactivity of cardiomyocyte membranes (cardiac muscle cells).
QUINIDINE SULPHATE (Chinidini sulfas) is a cinchona alkaloid, the ancestor of the first group of antiarrhythmic drugs. Simultaneously with the inhibition of the transport of sodium ions, it reduces the flow of calcium ions into the cardiac muscle cells, which ensures the accumulation of potassium ions in the myocardial cells, which inhibit the heart rhythm.
Quinidine sulfate has a strong antiarrhythmic effect, is active in various types of arrhythmias - extrasystole, atrial fibrillation, but quite often causes side effects (nausea, vomiting, etc.).
Quinidine is prescribed orally in tablets of 0.1 g 4-5 times a day, and if well tolerated, the dose is increased to 0.8-1 g per day.
Quinidine sulfate is produced in tablets of 0.1 and 0.2 g. List B.
NOVOCAINAMIDE (Novocainamidum) is close in chemical structure to novocaine, similar to it in pharmacological properties, has a local anesthetic effect. It has the most pronounced ability to reduce the excitability of the heart muscle and suppress foci of automatism in places where impulses are formed.
The drug has a quinine-like effect, and is used for the treatment of extrasystole, atrial fibrillation, paroxysmal tachycardia, during heart surgery, etc.
Novocainamide is prescribed orally in tablets of 0.25 g or 5-10 ml of a 10% solution is injected into a muscle or 5-10 ml of a 10% solution with glucose solution or 0.9% sodium chloride solution is injected into a vein.
The drug should not be used in cases of severe heart failure and hypersensitivity to him.
Novocainamide is produced in tablets of 0.25 and 0.5 g, as well as in the form of a 10% solution in ampoules of 5 ml. List B.
RHYTHMILEN (Styepit), synonym: disopyramide, is similar in action to quinidine, reduces the passage of sodium ions through the membrane, slows down the conduction of impulses along the His bundle.
Ritmilen is used for atrial and ventricular extrasystoles, tachycardia, arrhythmia, after myocardial infarction and during surgical interventions.
Ritmilen is prescribed orally in capsules or tablets up to 3 times a day.
Side effects include dry mouth, impaired accommodation, difficulty urinating and, rarely, allergic reactions.
Ritmilen is produced in tablets and capsules of 0.1 g and in the form of a 1% solution in ampoules of 1 ml.
Subgroup 1 B includes local anesthetics (see “Local anesthetics”). They increase the permeability of membranes for potassium ions, which inhibit the heart.
Subgroup 1 C includes the drugs Allapinin, Aymalin, Ethmozin, etc. They, like drugs of subgroup 1 A, suppress sodium transport through fast sodium channels of the cell membrane.
ALLAPININ (Aiiaripipit) has an antiarrhythmic effect, slowing down the conduction of impulses through the atria, His bundle and Purkinje fibers, does not cause hypotension, and has a local anesthetic and sedative effect.
Allapinin is used for supraventricular and ventricular extrasystole, atrial fibrillation and flutter, paroxysmal ventricular tachycardia and arrhythmia due to myocardial infarction.
Allapinin is prescribed orally in tablets, which are pre-crushed and taken 30 minutes before meals, 0.025 g every 8 hours, and if there is no effect, every 6 hours.
Side effects of the drug can be expressed in the form of dizziness, a feeling of heaviness in the head, redness of the face and sometimes allergic reactions.
Allapinin is produced in tablets of 0.025 g and in the form of a 0.5% solution in ampoules of 1 ml in a package of 10 pieces.
The second group of antiarrhythmic drugs are p-blockers, the main representatives of which are Anaprilin, Atenolol, Visken, Inderal, etc.
VISKEN (Ugyakep), synonym: pindolol, is a non-selective β-blocker, has antianginal, antiarrhythmic and hypotensive effects. As an antiarrhythmic agent it is especially effective for atrial extrasystoles, angina pectoris and hypertension. In cardiology, visken is used 1 tablet 3 times a day after meals.
Side effects sometimes include bronchospasm, bradycardia, headache, nausea and diarrhea.
Whisken is produced in tablets of 0.005 g.
The main representatives of the third group of antiarrhythmic drugs, which slow down the repolarization of cell membranes, are amiodarone, ornid and other drugs.
ORNID (Ogts!it) exhibits a sympatholytic effect by blocking the release of norepinephrine from nerve endings. Does not have a blocking effect on receptors, which leads to a decrease blood pressure, elimination of tachycardia and extrasystole.
To relieve attacks of arrhythmia, 0.5-1 ml of a 5% solution is injected into a vein or muscle, and for the prevention and treatment of arrhythmias, the same solution is injected into the muscle in the same doses 2-3 times a day.
You should not take the drug if acute disorders cerebral circulation, hypotension and severe renal failure.
Ornid is produced in ampoules of 1 ml of 5% solution in a package of 10 pieces.
The fourth group of antiarrhythmic drugs are calcium ion antagonists, or, as they are also called, calcium channel blockers (CCBs). The main drugs in this group are verapamil, nifedipine, dialtiazem, etc.
It is known that calcium ions increase the contractile activity of the myocardium and its oxygen consumption, affect the tone of the sinus node and atrioventricular conduction, constrict blood vessels, activate biochemical processes, stimulate the activity of the pituitary gland and the release of adrenaline by the adrenal glands, which therefore increases blood pressure.
Calcium channel antagonists are mainly used as cardiovascular drugs, they reduce blood pressure, improve coronary blood flow, and have antianginal and antiarrhythmic effects.
VERAPAMIL (UegaratePit) is a calcium channel blocker, reduces myocardial contractility, platelet aggregation, has an inhibitory effect on the conduction system of the heart, and increases the potassium content in the myocardium.
Verapamil is used for arterial hypertension, for the prevention of angina pectoris, especially in combination with atrial extrasystole and tachycardia.
The drug is prescribed orally 30 minutes before meals in tablets of 0.04 or 0.08 g for angina pectoris 3 times a day, and for hypertension - 2 times a day. To eliminate arrhythmias, verapamil is recommended to be used at a dose of 0.04-0.12 g 3 times a day.
Verapamil is produced in tablets of 0.04 and 0.08 g No. 50. List B.
NIFEDIPINE (M/esIrtitis), synonyms: Cordafen, Corinfar, like verapamil, dilates coronary and peripheral vessels, reduces blood pressure and myocardial oxygen demand, and has an antiarrhythmic effect.
Nifedipine is used for chronic heart failure, coronary heart disease with attacks of angina, to lower blood pressure in various forms of hypertension.
The drug is prescribed in tablets of 0.01-0.03 g 3-4 times a day.
Side effects sometimes include facial redness, upper jaw and torso.
Nifedipine is contraindicated in severe forms heart failure, severe hypotension, pregnancy and breastfeeding.
Nifedipine is produced in tablets of 0.01 g No. 40 and No. 50. List B.
This group also includes drugs Cardil, Pasikor and drugs that improve cerebral circulation(cinnarizine, cavinton, trental, etc.).
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