Arrhythmia today is defined in many people, because rarely what modern person is not subject to stressful situations, emotional and psychological stresses. There are forms of rhythm disturbance, like sinus arrhythmia, which are not dangerous for a person; when they are detected, specific treatment is rarely required. But other arrhythmic conditions are not so harmless.
Why is atrial fibrillation dangerous? First of all, a possible cardiac arrest, since with increased atrial contractility, ventricular activity also suffers. Therefore, it is important to know in which cases medical attention may be required due to the arising pathological condition.
Description of Atrial Fibrillation
Fibrillation should be understood as frequent contractile activity, when the whole heart or its individual parts are excited by uncoordinated, chaotic impulses. Atrial fibrillation (AF) - This is a definition of heart rate above 150 per minute, while the pathological focus of excitation is in the atria. In such cases, supraventricular tachycardia is 250-700 beats per minute, and the ventricular is slightly less - 250-400 beats per minute.
Atrial fibrillation is based on cyclic impulse transmission. Due to the effects of various factors (heart attack, ischemia, infection)
in the muscle tissue of the heart, areas with a disturbed conductive system are formed. The more of them, the higher the risk of developing fibrillation. If an impulse arrives at such a site, it cannot be transmitted further, therefore it returns and leads to contractility of already passed cardiomyocytes.
Normal impulse transmission
In some cases, pathological foci are created from heart cells, which themselves begin to generate an impulse. If there are many such foci, the work of the heart becomes uncoordinated and chaotic. No matter how pathological impulses in the atria are created, they do not fully reach the ventricles, so the latter does not contract as fast as the atrial part of the fibers.
Symptoms of Atrial Fibrillation
The clinical picture is more dependent on the severity of hemodynamic disturbances. If they are absent, the course of the disease may be asymptomatic. Severe manifestations can cause irreversible consequences, leading to heart failure.
The episodes of atrial fibrillation, expressed in paroxysms, may be accompanied by:
- chest pain
- frequent urination.
The occurrence of shortness of breath, dizziness, weakness indicates a developing heart failure. In severe cases, fainting and fainting conditions are observed.
Heart rate deficiency - one of the features of fibrillation. If at the top of the heart a frequent heartbeat is heard, then when it is compared with a pulse on the wrist, a lack of pulsation is determined. This happens due to insufficient ejection of blood by the left ventricle, despite a frequent heartbeat.
Thromboembolism, often expressed as a stroke, may be the first sign of atrial fibrillation in those patients who have not complained or have experienced rare paroxysm attacks.
Causes of Atrial Fibrillation
In most cases, AF develops against a background of diseases of the cardiovascular system. In the first place is arterial hypertension, which contributes to the formation of pathological foci that generate extraordinary impulses. Heart failure and acquired heart defects, in which hemodynamics are significantly impaired, have a lot of influence in the development of arrhythmias.
Children can also develop atrial fibrillation. The reason for this is congenital malformations - one ventricle, atrial septal defect, surgery associated with valve repair.
In diseases such as cardiomyopathy and coronary heart disease, areas with a disturbed conductive system form in the heart muscle. As a result, electrical impulses are not fully transmitted, but form cyclical foci of excitation. A large number of such foci contributes to clinically unfavorable atrial fibrillation.
Among young people, in 20% -45% of cases, depending on the type of AF, pathology develops without cardiovascular disorders.
Of the non-cardiac factors that play a role in the development of AF, hyperthyroidism, chronic renal disease, diabetes mellitus, chronic obstructive pulmonary disease, and obesity are distinguished. Studies have also confirmed the risk of heredity of AF, as in 30% of the examined parents had this disease.
Video: Atrial fibrillation, root causes
Atrial fibrillation is one of the most common arrhythmias. This disease affects 1-2% of the total population, and this indicator has been growing in recent years and is likely to increase in the next 50 years due to an aging population. The number of patients with AF in the United States is estimated at more than 2.2 million people, in the countries of the European Union - 4.5 million. According to the Framingham study, the risk of AF in men and women over 40 is 26 and 23%, respectively. AF is detected in approximately 6-24% of stroke patients. The prevalence of AF also increases with age, amounting to about 8% in patients older than 80 years.
|First identified||first episode AF|
|Paroxysmal||the attack lasts no more than 7 days (usually less than 48 hours) and is spontaneously restored to the sinus rhythm|
|Persistent||the attack lasts more than 7 days|
|Long lasting||the attack lasts more than 1 year, but a decision was made to restore the sinus rhythm|
|Constant||long-term AF (for example, more than 1 year), in which cardioversion was ineffective or not performed|
|II||Mild symptoms, normal activities not disturbed|
|III||Severe symptoms, changed daily activity|
|IV||Disabling symptoms, normal daily activity is not possible|
Depending on the heart rate, there are tachy- (heart rate> 90 per minute), normo-and bradisystolic (heart rate.
In addition, in 2010 the European Society of Cardiology proposed a clinical classification of EHRA (European Heart Rhythm Association) depending on the severity of the symptoms of the disease.
Atrial fibrillation is associated with various cardiovascular diseases that contribute to the development and maintenance of arrhythmias. These include :
About 30–45% of cases of paroxysmal AF and 20–25% of cases of persistent AF occur in young people without heart disease (an isolated form of AF).
There are also risk factors not related to heart disease. These include hyperthyroidism, obesity, diabetes, COPD, sleep apnea, chronic kidney disease. A history of AF in close relatives of the patient may increase the risk of AF. A study of more than 2200 patients with AF showed that 30% of them have parents with AF. Various genetic mutations may be responsible for the development of AF.
Minimal amounts of alcohol (about 10 grams per day) are associated with a 5% increased risk of developing atrial fibrillation.
AF can also develop with excessive alcohol consumption (festive heart syndrome), heart surgery, and electric shock. In such conditions, treatment of the underlying disease often leads to normalization of the rhythm. A risk factor for AF is HIV infection.
Organic heart disease can cause structural remodeling of the atria and ventricles. In the atria, this process is due to the proliferation and differentiation of fibroblasts into myofibroblasts, increased deposition of connective tissue and fibrosis. All this leads to electrical dissociation of muscle bundles and heterogeneous conduct, thereby contributing to the development and maintenance of AF.
There are many hypotheses about the mechanisms of AF development, but the theory of focal mechanisms and the hypothesis of multiple small waves are the most common. Moreover, these mechanisms can be combined with each other. Focal mechanisms include trigger activity and microreentry-type excitation circulation. According to this theory, AF occurs as a result of the arrival of many impulses from autonomous foci, which are most often located at the mouth of the pulmonary veins or along the posterior wall of the left atrium near the junction with the pulmonary vein. Tissues in these zones have a shorter refractory period, which brings them closer to the cells of the sinus node in properties. As the paroxysmal form progresses to a constant, foci of increased activity are distributed throughout the atria. According to the hypothesis of multiple shallow waves, the phase transition is retained as a result of randomly conducting many independent shallow waves.
Changes in the atria occur after AF. At the same time, the atrial refractory period is shortened by suppressing the flow of calcium ions through L-type channels and increasing the flow of potassium ions into the cells. The contractile function of the atria also decreases due to a slowdown in the intake of calcium ions into the cells, impaired release of calcium ions from intracellular depots, and impaired energy metabolism in myofibrils. The blood flow in the atria is slowed down due to the violation of their contraction, which leads to the formation of blood clots mainly in the left atrial ear.
Depending on the severity of hemodynamic disturbances, the clinical picture varies from an asymptomatic course to severe manifestations of heart failure. With a paroxysmal form, episodes of atrial fibrillation are sometimes asymptomatic. But usually patients feel a rapid heartbeat, discomfort or pain in the chest. Heart failure also occurs, which manifests itself as weakness, dizziness, shortness of breath, or even fainting conditions and fainting. An attack of AF may be accompanied by increased urination, due to increased production of atrial natriuretic peptide.
The pulse is arrhythmic, pulse deficiency may occur (heart rate at the apex of the heart is greater than on the wrist) due to the fact that with frequent ventricular rhythm, the shock volume of the left ventricle is insufficient to create a peripheral venous wave. In patients with asymptomatic AF or with minimal manifestations of AF, thromboembolism (usually in the form of a stroke) may be the first manifestation of the disease.
If there are characteristic complaints, an anamnesis of the disease is collected in order to determine its clinical form (for example, find out the beginning of the first attack or the date of detection), the causes and risk factors, the effectiveness of antiarrhythmic drugs for this patient in previous attacks.
To diagnose AF, a standard 12-lead ECG is used. In this case, the following ECG signs are detected: the absence of P waves, fibrillation waves f with different amplitudes and shapes, absolutely different RR intervals (QRS complexes are usually not changed). Also, an associated ECG pathology is determined by an ECG (myocardial infarction in the past, other arrhythmias, etc.). If a paroxysmal form is suspected and there is no ECG during an attack, Holter monitoring is performed.
In addition, echocardiography is performed to detect organic heart pathology (for example, valve pathology), atrial sizes. Also, thrombi in the ears of the atria are determined by this method, however, for this, the transesophageal Echo-KG is more informative than the transthoracic. When AF is first detected, difficulties in controlling the rhythm of the ventricles, or unexpected relapse after cardioversion, the function of the thyroid gland (the level of thyroid-stimulating hormone in the blood serum) is evaluated.
Normally, atrial contractions contribute to the filling of the ventricles with blood, which is impaired in AF. This does not affect the heart without another pathology, but in patients with already reduced ventricular filling, the cardiac output is insufficient. Therefore, the disease can be complicated by acute heart failure.
With atrial fibrillation, blood clots form in the left atrium, which can flow into the blood vessels of the brain with a blood stream, causing an ischemic stroke. The incidence of this complication in patients with atrial fibrillation of non-rheumatic etiology averages 6% per year.
In the treatment of AF, there are 2 types of strategies:
- Rhythm control strategy - with the help of cardioversion restore normal sinus rhythm and then prevent relapse,
- The strategy for controlling heart rate is to preserve AF with drug reduction in the frequency of ventricular contractions.
Anticoagulant therapy is also performed to prevent thromboembolism.
Forms of Atrial Fibrillation
The first identified and constant varieties of AF are clear from the names, while the rest require clarification.
Paroxysmal AF - develops suddenly and lasts no more than 48 hours, but by definition, this form of AF can last up to 7 days. With this violation, the sinus rhythm is restored independently.
Persistent AF - The attack also occurs suddenly and lasts more than 7 days.
Long-lasting form observed in the patient throughout the year and to normalize the condition, a decision is made on the choice of treatment method (as a rule, cardioversion is used).
Anticoagulant Therapy Edit
|C||Congestive heart failure (Chronic heart failure)||1|
|H||Hypertension (arterial hypertension)||1|
|A||Age (Age) ≥ 75 years old||1|
|D||Diabetes mellitus diabetes||1|
|S2||Stroke or TIA (history of transient or transient ischemic attack)||2|
|C||Congestive heart failure or Left ventricular systolic dysfunction (Chronic heart failure or left ventricular dysfunction)||1|
|H||Hypertension (arterial hypertension)||1|
|A2||Age (Age) ≥ 75 years old||2|
|D||Diabetes mellitus (diabetes mellitus)||1|
|S2||Stroke or TIA or thromboembolism (Stroke, or transient ischemic attack, or a history of thromboembolism)||2|
|V||Vascular disease (Vascular diseases, i.e. peripheral arterial disease, myocardial infarction, aortic atherosclerosis)||1|
|A||Age (Age) 65-74 years||1|
|Sc||Sex category (Female)||1|
Anticoagulant therapy is necessary to prevent the most formidable complication of AF - thromboembolism. For this purpose, oral anticoagulants (warfarin, rivaroxaban, apixaban, dabigatran) or acetylsalicylic acid (or clopidogrel) are used. Indications for anticoagulation and drug choice are determined by the risk of thromboembolism, which is calculated according to the CHADS scales2 or CHA2DS2-VASc. If the sum of points on the CHADS scale2 ≥ 2, then in the absence of contraindications, long-term therapy with oral anticoagulants (for example, warfarin with maintenance of INR 2-3 or new oral anticoagulants) is indicated. If the sum of points on the CHADS scale2 0-1, recommend a more accurate assessment of the risk of thromboembolism on a CHA scale2DS2-VASc. Moreover, if ≥ 2 points, oral indirect anticoagulants are prescribed, 1 point is oral indirect anticoagulants (preferably) or acetylsalicylic acid 75–325 mg per day, 0 points are not prescribed anticoagulant therapy (preferred), or acetylsalicylic acid in the same dose .
However, anticoagulant therapy is dangerous for bleeding. To assess the risk of this complication, the HAS-BLED scale has been developed. A score of ≥ 3 indicates a high risk of bleeding, and the use of any antithrombotic drug requires special care.
|H||Hypertension (arterial hypertension)||1|
|A||Abnormal renal / liver function (impaired liver or kidney function - 1 point each)||1 or 2|
|S||Stroke (a history of stroke)||1|
|B||Bleeding history or predisposition (History of bleeding or tendency to it)||1|
|L||Labile INR (Labile INR)||1|
|E||Elderly (Age> 65 years)||1|
|D||Drugs / alcohol concomitantly (Taking certain drugs / alcohol - 1 point each)||1 or 2|
Types of Atrial Fibrillation
They were represented by various European public organizations, as well as the American Heart Association. The classification of the four types was based on the number of heart contractions:
the first type is normosystolic (heart rate from 60 to 90 per min.),
the second is bradysystolic (heart rate less than 60 per min.),
the third is tachysystolic (heart rate more than 90 per min.),
the fourth is paroxysmal (heart rate of 150 per minute or more).
Clinical Classification EHRA
It was proposed in 2010 by the European Society of Cardiology. The severity of the signs of the disease formed the basis of the clinical classification, according to which there are four classes of severity of the process:
I - symptoms are not detected,
II - the patient leads a familiar lifestyle, although he notes mild signs of the disease,
III - the patient's ability to work is violated due to a pronounced clinic,
IV - severe organic changes have led the patient to disability.
Diagnosis of Atrial Fibrillation
Most often, patients turn with characteristic complaints to the clinic to the local doctor. If they are not, but there is a suspicion of AF, other important patient data is collected:
- when the attack was first noticed,
- how long did it last
- if previously treated, the drugs taken and their effectiveness are clarified.
During the examination of the patient, the following can be determined: pulse deficiency, high blood pressure, palpitations during listening, frequent, muffled tones on the basis of the heart. Further, additional research methods are assigned and the first thing is electrocardiography.
ECG signs of atrial fibrillation:
- P wave on all leads is absent,
- fibrillation waves f are determined,
- between RR different distances are noted.
If there are signs of fibrillation, but failed to fix them on a standard ECG, then Holter monitoring is performed.
Echocardiography - is done in order to identify organic disorders. These may be valvular defects or a recent leg-transmitted myocardial infarction. Also, using the Echo-KG determine the size of the atria, which in the case of pathology can be impaired. This diagnostic method allows you to “see” thrombotic formations in the ears of the atria, although transesophageal Echo-KG provides more information on this pathology.
Chest x-ray - Helps determine the expansion of the chambers of the heart, assess the condition of the main vessels.
Blood testswith the help of which the level of the main hormones secreted by the thyroid gland (triiodothyronine, thyroxine) and the pituitary gland (thyroid stimulating hormone) is determined.
Complications of Atrial Fibrillation
Acute heart failure - develops if the patient has, in addition to AF, another cardiovascular pathology. If the patient does not have a concomitant pathology, then acute disorders are not observed.
Ischemic stroke - develops as a result of the entry of blood clots from the left atrium into the vessels of the brain. Complication occurs with a frequency of 6% per year, with more concern for patients with non-rheumatic pathology. Therefore, it is very important to prevent thromboembolism with appropriate treatment.
Rhythm Control Strategy
Sinus rhythm restoration is carried out using an electric discharge (electric cardioversion) or antiarrhythmic drugs (pharmacological cardioversion). Previously, with a tachysystolic form, heart rate is reduced to about 80-100 per minute by oral administration of β-blockers (metoprolol) or non-dihydropyridone calcium antagonists (verapamil). Cardioversion is known to increase the risk of thromboembolism. Therefore, before a planned cardioversion, if AF lasts more than 48 hours or if the duration is unknown, anticoagulant therapy with warfarin is mandatory for three weeks and four weeks after the procedure. An emergency cardioversion is performed if AF lasts less than 48 hours or is accompanied by severe hemodynamic disturbances (hypotension, decompensation of heart failure), only under the guise of unfractionated or low molecular weight heparin.
Treatment of Atrial Fibrillation
The key areas of AF therapy are:
- Heart rhythm control - they restore sinus rhythm, and then support it with the prevention of relapse.
- Heart rate control - fibrillation persists, but with the help of drugs, the heart rate is reduced.
Anticoagulant treatment is used to prevent the development of thromboembolism.
Electric Cardio Version
Electric cardioversion is more effective than pharmacological, but it is painful and therefore requires the introduction of sedatives (e.g. propofol, midazolam) or surface general anesthesia. In modern cardioverter defibrillators, the discharge is automatically synchronized with the R wave to prevent electrical stimulation in the phase of ventricular repolarization, which can provoke ventricular fibrillation. In a two-phase discharge, start from 100 J, if necessary, the strength of each next discharge is increased by 50 J. A single-phase discharge requires 2 times more energy, that is, start from 200 J, with a subsequent increase of 100 J, until a maximum level of 400 J is reached Thus, a two-phase pulse has advantages, since the effect is achieved with less energy.
Heart rate control
Sinus rhythm is restored in two ways:
- Electric cardioversion - A rather painful procedure, but at the same time effective. Sedatives are administered for pain relief, or general anesthesia is performed. Cardioverter defibrillators are two-phase and single-phase. The former are more powerful and therefore deliver a lower discharge while achieving the desired result more quickly. Single-phase devices deliver a smaller discharge, so more energy is used to achieve the desired effect.
- Pharmacological Cardioversion - based on the use of antiarrhythmic drugs in the form of amiodarone, nibentan, procainamide, propafenone.
If the patient has a tachysystolic AF, then the heart rate decreases to 100-90 times per minute. For this, tablet forms of metoprolol (beta-blockers) or verapamil (calcium antagonist) are used. In order to prevent thromboembolism, warfarin (an indirect anticoagulant) is prescribed, which is taken both before the procedure and after it for three to four weeks.
Heart rate control
It is based on the use of medications with which heart rate drops to 110 per minute in a calm state. Medicines are taken from various groups of action and are combined in treatment regimens.
- cardiotonics (digoxin),
- calcium antagonists (verapamil, diltiazem),
- beta-adrenergic blockers (carvedilol, metoprolol).
Amiodarone is prescribed in case of ineffective treatment with the above drugs. It has a pronounced antiarrhythmic effect, but with caution should be prescribed to persons under 18 years of age, the elderly, during pregnancy and the presence of concomitant pathology in the form of bronchial asthma, liver and chronic heart failure.
Radiofrequency catheter ablation
It is carried out in order to alleviate the patient's condition in the absence of the effect of drug therapy. There are various methods of surgical intervention:
- The ablation of the mouth of the pulmonary veins is effective in 70% of cases, although it has not been studied enough for widespread use.
- “Labyrinth” - effective in 50% of cases, is carried out with the aim of creating a single path of transmission of an electrical signal. The technique is under study.
- Ablation of the pathological lesion and AV connection - the result is effective in 50%, while the ablation of the AV node is justified in case of chronic AF.
- Open heart surgery - it is advisable to treat AF in case of surgery due to another cardiovascular disease.
Video: Atrial Fibrillation
Emergency Atrial Fibrillation
Isoptin is first administered intravenously. If the attack is not stopped, a mesatone with novocainamide is administered, while blood pressure and an electrocardiogram are controlled (broadening of the ventricular complex is a sign of cessation of drug administration).
In emergency care, beta-blockers (obzidan) and ATP (most often with nodular forms) are used. You can also present in the form of a table the choice of the drug in order to stop the attack of AF.
Propafenone should be taken for the first time only under medical supervision, since a sharp drop in blood pressure is possible.
The lack of results from the use of medicines encourages cardioversion. Other indications for the procedure are:
- the duration of fibrillation is 48 hours or more,
- the patient has hemodynamic disturbances in the form of low blood pressure, a decompensated form of heart failure.
A direct-acting anticoagulant is mandatory - heparin (low molecular weight or non-fractional).
Secondary prevention of atrial fibrillation
Prevention of relapse is called secondary prophylaxis of AF. Based on various studies, it was determined that the correct heart rhythm persists for one year on average in 40% of patients. Atria tend to remember arrhythmias, so you need to make a lot of effort to prevent their return. First of all, you should follow these recommendations:
- It is necessary to carry out therapy of the main diseases that complicate the course of fibrillation.
- Take antiarrhythmic drugs and correct them in time while reducing the effectiveness of treatment.
- Refuse alcohol, since every 10 grams taken daily increase the risk of myocardial infarction by 3%.
Video: Atrial fibrillation: pathogenesis, diagnosis, treatment
What it is?
Atrial fibrillation is a rhythm disturbance in which the muscle fibers of a given part of the heart contract not only at random, but also with great frequency - from 300 to 600 beats per minute. Moreover, the process is inconsistent, chaotic and also leads to ventricular dysfunction. Outwardly, such a "dance" of the heart is manifested by an increased pulse. The latter is often difficult to probe, because it seems to flicker. It is this comparison that gave pathology a second name - atrial fibrillation.
Next to the wording of the diagnosis in the disability sheet, you can find the code I 48, which belongs to atrial fibrillation in the ICD of the 10th revision.
We have to admit that, despite the tremendous achievements of medicine in the treatment of this disease, it remains a key cause of stroke, heart failure and sudden death. Moreover, an increase in the number of such patients is predicted. The latter is associated with an increase in life expectancy and, accordingly, the number of elderly people suffering from arrhythmia.
What is the difference between fibrillation and flutter
I want to note that the identification of these two rhythm disturbances is considered a common mistake. In fact, atrial fibrillation and flutter have a different genesis and manifestations. The first is characterized by:
- random reduction of cardiomyocytes (heart muscle cells) with different intervals between them,
- the presence of multiple lesions located in the left atrium and creating extraordinary pathological discharges.
Flutter - An easier variant of arrhythmia. Although the heart rate reaches 200-400 beats per minute, but the heart beats at the same time at regular intervals. This is possible due to a coordinated contraction of muscle fibers, since the impulses come from one focus of excitation. Read more about this type of rhythm disturbance here.
Prevalence in society
The tachysystolic form of atrial fibrillation, which is the most common, occurs in 3% of adults aged 20 years and older. Moreover, older people suffer from the disease to a greater extent. This trend is due to several factors:
- increase in life expectancy,
- early diagnosis of asymptomatic forms of pathology,
- the development of concomitant diseases that contribute to the appearance of atrial fibrillation.
According to the World Health Organization, in 2010, pathology was detected in 33.5 million people on the planet.
It was revealed that the risk of getting sick in women is slightly lower than in men. But at the same time, the former are more often susceptible to strokes, have a greater number of concomitant diseases and a pronounced clinic of fibrillation.
Causes of the disease and genetic aspects
I want to note that it is very important to distinguish the true cause of atrial fibrillation from factors that only contribute to the manifestation of the disease.
The pathology is based on a genetic mutation, a kind of "breakdown". Even if there are no associated cardiovascular risks, the chance of getting atrial fibrillation in patients with such a DNA defect is very high.
At the moment, about 14 variants of changes in the genotype are known, leading to rhythm disturbance. It is believed that the most frequent and significant mutation is located on chromosome 4q25.
In this situation, a complex violation of the structures and functions of the myocardium of the atria occurs - it is remodeled.
In the future, it is supposed to resort to the help of genomic analysis, which will improve the prognosis of the disease and reduce disability due to early diagnosis of pathology and timely treatment.
Signs on an ECG
Examination of the patient, especially in old age, with the help of an ECG should be carried out during each of his visits to the doctor. This can significantly reduce the number of consequences of atrial fibrillation (ischemic stroke, acute heart failure) and improve the diagnosis of latent (asymptomatic) and its paroxysmal forms. Therefore, when you are advised to undergo this procedure at an outpatient appointment or in a hospital, you can’t refuse, because many patients do not feel any interruptions in the heart at all until the occurrence of a “vascular accident”.
New methods are being developed that will allow you to independently determine violations. For example, dermal portable recorders, smartphones with ECG electrodes, tonometers with built-in algorithms for detecting arrhythmias.
But all of them are still inferior in terms of informativeness to the traditional cardiogram, on which the following changes are detected during atrial fibrillation:
- there is no P wave,
- R-R intervals, responsible for the rhythm of the ventricles, have different lengths,
- there are waves ff, considered the main sign of the disease.
I draw your attention to the fact that in order to diagnose a paroxysmal form of pathology, one should resort to either daily short-term ECG recording or round-the-clock Holter monitoring.
The photo below shows examples of films of people with atrial fibrillation.
Why is fibrillation dangerous?
When contractions are chaotic, the blood lingers in the atria longer. This leads to blood clots.
Large blood vessels come from the heart, which carry blood to the brain, lungs, and all internal organs.
- The resulting thrombi in the right atrium along the large pulmonary trunk enter the lungs and lead to pulmonary embolism.
- If blood clots formed in the left atrium, then with the flow of blood through the vessels of the aortic arch, they enter the brain. This leads to the development of a stroke.
- In patients with atrial fibrillation, the risk of stroke (acute cerebrovascular accident) is 6 times higher than without rhythm disturbance.
Causes of pathology
The reasons are usually divided into two large groups:
Rarely, with a genetic predisposition and anomalies in the development of the conduction system of the heart, this pathology can be an independent disease. In 99% of cases, atrial fibrillation is not an independent disease or symptom, but occurs against the background of the underlying pathology.
1. Cardiac causes
The table shows how often cardiac pathology occurs in patients with AF:
|Heart causes||How often do patients with AF diagnose heart problems|
|Valvular heart disease||30%|
|Coronary heart disease, arterial hypertension||20%|
|Cardiomyopathies - Congenital or acquired damage to the heart muscle||10%|
|Condition after cardiac surgery||70%|
Among all malformations, atrial fibrillation is most often detected with mitral or multivalvular heart defects. The mitral valve is the valve that connects the left atrium and left ventricle. Multivalvular defects are the defeat of several valves: mitral and (or) aortic and (or) tricuspid.
Mitral heart disease
A combination of diseases may also be the cause. For example, heart defects can be combined with coronary heart disease (coronary disease, angina pectoris) and arterial hypertension (high blood pressure).
The condition after cardiac surgery can cause atrial fibrillation, because after the operation can occur:
Change in intracardiac hemodynamics (for example, there was a bad valve - a good one was implanted, which began to work correctly).
Violation of the electrolyte balance (potassium, magnesium, sodium, calcium). Electrolyte balance ensures electrical stability of heart cells
Inflammation (due to sutures on the heart).
In this case, the recommendations of doctors depend on heart surgery and rhythm disturbances. If there were no such problems before the operation, then arrhythmia will “go away” in the process of general treatment.
2. Non-cardiac causes
|Heartless reasons||How often|
|Obesity||25% of patients|
|Diabetes||20% of patients|
|Hyperthyroidism||10% of patients|
|Adrenal Tumors||10% of patients|
Alcohol consumption can affect the risk of atrial fibrillation. A study conducted by American scientists in 2004 showed that with an increase in the dose of alcohol over 36 grams per day, the risk of developing atrial fibrillation increases by 34%. Интересно и то, что дозы алкоголя ниже этой цифры не влияют на развития ФП.
Вегетососудистая дистония – это комплекс функциональных расстройств нервной системы. При этой болезни встречается часто пароксизмальная аритмия (описание видов аритмии – в следующем блоке).
Классификация и симптомы ФП
Существует много принципов классификаций ФП. The most convenient and generally accepted classification is based on the duration of atrial fibrillation.
|FP form||Duration||Outcome or treatment recommendations|
|First diagnosed or occurring||10-15 minutes|
Treatment can restore sinus rhythm
* Paroxysms are seizures that can occur and stop spontaneously (that is, on their own). The frequency of attacks is individual.
All types of fibrillation have similar symptoms. When atrial fibrillation occurs against the background of the underlying disease, then most often patients present the following complaints:
- Heartbeat (a frequent rhythm, but with a bradysystolic form, the heart rate, on the contrary, is low - less than 60 beats per minute).
- Interruptions ("freezing" of the heart and then a rhythm follows, which can be frequent or rare). Frequent rhythm - more than 80 beats per minute, rare - less than 65 beats per minute).
- Shortness of breath (rapid and labored breathing).
If atrial fibrillation exists for a long time, then swelling on the legs develops in the evening.
If the rhythm can be restored, then the doctors will make every effort for this.
The drugs used to treat AF are presented in the table. These recommendations are generally accepted for stopping rhythm disturbances by the type of atrial fibrillation.
|Drugs that affect the work and heart rate|
|Cardiac Glycosides||The drug is good in that by reducing heart rate, it improves the strength of contractions|
|Amiodarone type antiarrhythmics||Used to restore rhythm. Used with caution in case of thyroid dysfunction.|
|Potassium and magnesium preparations||By eliminating the imbalance, heart rate is reduced. With intravenous can restore the rhythm|
|Sodium channel blockers||Effective for restoring rhythm at the very beginning of AF|
Sometimes treatment with medications (intravenous or tablets) becomes ineffective, and the rhythm cannot be restored. In this situation, electro-pulse therapy is carried out - this is a method of influencing the heart muscle by the discharge of an electric current.
Distinguish between external and internal methods:
External is carried out through the skin and chest. Sometimes this method is called cardioversion. Atrial fibrillation stops in 90% of cases if treatment is started on time. In cardiac surgical hospitals, cardioversion is very effective and is often used for paroxysmal arrhythmias.
Inner. A thin tube (catheter) is inserted into the cavity of the heart through the large veins of the neck or in the area of the clavicle. An electrode is held along this tube (similar to wiring). The procedure takes place in the operating room, where under the control of radiography, the doctor on the monitors can visually assess how to properly orient and install the electrode.
Then, using special equipment shown in the figure, they discharge and look at the screen. On the screen, the doctor can determine the nature of the rhythm (the sinus rhythm has recovered or not). A persistent form of atrial fibrillation is the most common case when doctors use this technique.
When all methods are ineffective, and atrial fibrillation significantly worsens the patient’s life, they recommend eliminating the focus (which sets the heart rhythm incorrectly), which is responsible for the increased frequency of contractions - radio frequency ablation (RFA) - treatment using radio waves.
After elimination of the focus, the rhythm may be rare. Therefore, RFA can be combined with the implantation of an artificial pacemaker - a pacemaker (a small electrode into the heart cavity). A pacemaker, which is placed under the skin in the clavicle, will set the heart rhythm through the electrode.
How effective is this method? If RFA was performed for a patient with a paroxysmal AF, then the sinus rhythm is maintained at 64–86% during the year (2012 data). If there was a persistent form, then atrial fibrillation returns in half the cases.
Why is it not always possible to restore the sinus rhythm?
The main reason when it is not possible to restore the sinus rhythm is the size of the heart and left atrium.
If the ultrasound of the heart sets the size of the left atrium to 5.2 cm, then in 95% restoration of the sinus rhythm is possible. This is reported by arrhythmologists and cardiologists in their publications.
When the size of the left atrium is more than 6 cm, then restoration of the sinus rhythm is impossible.
An ultrasound of the heart shows that the size of the left atrium is more than 6 cm
Why is this happening? When this part of the heart is stretched, some irreversible changes occur in it: fibrosis, degeneration of myocardial fibers. Such a myocardium (the muscle layer of the heart) is not only unable to hold the sinus rhythm for seconds, but, as cardiologists believe, it should not.
If AF is diagnosed in a timely manner, and the patient complies with all the doctor's recommendations, then the chances to restore the sinus rhythm are high - more than 95%. We are talking about situations where the size of the left atrium is not more than 5.2 cm, and the patient is diagnosed for the first time with arrhythmia or paroxysm of atrial fibrillation.
Sinus rhythm, which can be restored after RFA in patients with a persistent form, persists throughout the year in 50% of cases (of all patients who underwent surgery).
If arrhythmia exists for several years, for example, for more than 5 years, and the heart is “large” in size, then the doctors' recommendations are medication that will help the work of such a heart. The rhythm cannot be restored.
The quality of life of patients with AF can be improved by following the recommended treatment.
If the cause is alcohol and smoking, then it is enough to eliminate these factors so that the rhythm normalizes.
If blinking accompanies obesity, then the doctor’s recommendations are obvious - you need to lose weight. In this case, the chances of recovery are high.
For pharmacological cardioversion, antiarrhythmic drugs of IA, IC and III classes are used. These include procainamide, amiodarone, propafenone, nitrophenyl diethylaminopentylbenzamide (nibentan).
Procainamide is released in 5 ml ampoules containing 500 mg of the drug (10% solution). It is administered in a jet or drip at a dose of 500-1000 mg once intravenously slowly (for 8-10 minutes or 20-30 mg / min). In the 2010 European Recommendations, it was excluded from the list of drugs for cardioversion. However, in the Russian Federation, due to its low cost, it is very common. Side effects of procainamide include arterial hypotension, weakness, headache, dizziness, dyspepsia, depression, insomnia, hallucinations, agranulocytosis, eosinophilia, lupus-like syndrome.
Propafenone is released in 10 ml ampoules containing 35 mg of the drug, and in tablets of 150 and 300 mg. Introduced at a dose of 2 mg / kg intravenously for 10 minutes (expected effect from 30 minutes to 2 hours) or orally at a dose of 450-600 mg (expected effect after 2-6 hours). The drug is ineffective with persistent AF and atrial flutter. It should not be used in patients with reduced contractility of the left ventricle and myocardial ischemia. Due to the presence of a weak β-blocking effect, it is contraindicated in patients with severe COPD.
Amiodarone is released in 3 ml ampoules containing 150 mg of the drug (5% solution). It is injected intravenously at a dose of 5 mg / kg for 15 minutes, then they are continued to drip at a dose of 50 mg / h for 24 hours. It restores the sinus rhythm slowly, its maximum effect - after 2-6 hours. Amiodarone is recommended for use in patients with organic heart disease.
Nibentan is released in 2 ml ampoules containing 20 mg of the drug (1% solution). Introduced intravenously at a dose of 0.065-0.125 mg / kg for 3-5 minutes. If there is no effect, repeat infusions in the same dose with an interval of 15 minutes (up to a maximum dose of 0.25 mg / kg). Its use is allowed only in intensive care wards with ECG monitoring within 24 hours after administration, as the development of proarrhythmic effects in the form of polymorphic ventricular tachycardia of the pirouette type is possible, as well as lengthening of the QT interval with the appearance of the U wave.
Long-term rhythm control
In order to prevent relapse of AF in some cases, antiarrhythmic drugs are prescribed for a long time. However, their effectiveness for controlling sinus rhythm is low, and side effects are very dangerous, so the choice of a particular drug is determined by its safety. For this, amiodarone, sotalol, diethylaminopropionylethoxycarbonylaminophenothiazine (ethacyzine), dronedarone, lappaconitine hydrobromide (allapinin), morazizin (ethmosine), propafenone are used.
Heart Rate Control Strategy Edit
When choosing a strategy for controlling heart rate, attempts to restore a normal heart rhythm are not made. Instead, various groups of drugs are used that can reduce heart rate: beta-blockers (metoprolol, carvedilol, etc.), non-dihydropyridine calcium channel blockers (verapamil and diltiazem), digoxin. With their ineffectiveness, the appointment of amiodarone or dronedarone is possible. Heart rate control allows you to reduce the severity of symptoms of arrhythmia, but does not stop the progression of the disease.
The purpose of this strategy is to keep heart rate at rest.
With the ineffectiveness of the above treatment methods, catheter ablation is sometimes used. In order to restore and maintain sinus rhythm, radiofrequency ablation is performed.
Catheter RFA is usually performed in patients with paroxysmal atrial fibrillation, which is resistant to at least one antiarrhythmic drug. This practice is justified by the results of numerous studies in which ablation led to better heart rhythm control compared with antiarrhythmic drugs.
In this case, the electrical isolation of the trigger sites from the mouths of the pulmonary veins from the surrounding tissue of the left atrium is performed. To perform this procedure, a circular diagnostic catheter is inserted into the mouth of the pulmonary veins, and using the so-called “irrigated” ablation electrode, circular ablation is performed in the “antrum” of the pulmonary veins.
When manipulating a catheter, the doctor needs to visualize his position in the left atrium in relation to other structures. Previously, only a fluoroscopic method for visualizing catheters was available to surgeons.
The determination of the spatial location of the zones of the heart from which electrograms are recorded using x-rays suffers from a large error and is associated with a large dose of x-ray radiation for both the patient and the medical staff (x-ray radiation is ionizing).
Modern electroanatomical mapping technologies, which combine anatomical and electrophysiological information, allow surgeons to create a three-dimensional map of the heart chamber of interest. The ability to control the catheter without x-rays significantly reduces the time of x-ray irradiation and the total procedure time.
There is also a method of ablation of the atrioventricular site: the AV site or the bundle of His is destroyed by radio-frequency current, causing a complete transverse blockade. Then an artificial pacemaker is implanted, which “imposes” a heart rhythm that is close to normal in characteristics. This is a palliative intervention that improves the quality of life of the patient, but does not affect mortality.