Atrial fibrillation (AF) is a synonym for the term “Atrial fibrillation” that is more commonly used in the CIS countries.
Atrial fibrillation is the most common heart rhythm disorder. AF is not associated with a high risk of sudden death, so it is not classified as a fatal rhythm disorder, such as ventricular arrhythmias.
Atrial fibrillation (AF) is one of the most common types of supraventricular tachyarrhythmias. Fibrillation refers to the rapid irregular contraction of the atria, and the frequency of their contractions exceeds 350 per minute. The appearance of AF is characterized by an irregular contraction of the ventricles. AF accounts for more than 80% of all paroxysmal supraventricular tachyarrhythmias. Atrial fibrillation is possible in patients of all age categories, but in elderly patients, the prevalence of the syndrome increases, which is associated with an increase in organic heart disease.
Causes and Risk Factors
- AMI (myocardial conduction and excitability).
- Arterial hypertension (LV and LV overload).
- Chronic heart failure (violation of the structure of the myocardium, contractile function and conduction).
- Cardiosclerosis (replacement of myocardial cells with connective tissue).
- Myocarditis (violation of the structure during inflammation of the myocardium).
- Rheumatic vices with valve damage.
- SU dysfunction (tahi-brady syndrome).
- Thyroid diseases with manifestations of thyrotoxicosis.
- Drug or other intoxication.
- Overdose of digitalis preparations (cardiac glycosides) in the treatment of heart failure.
- Acute alcohol intoxication or chronic alcoholism.
- Uncontrolled diuretic therapy.
- Overdose of sympathomimetics.
- Hypokalemia of any origin.
- Stress and psycho-emotional stress.
Age-related organic changes. With age, the structure of the atrial myocardium undergoes changes. The development of small focal cardiac sclerosis can cause fibrillation in old age.
Atrial fibrillation classification
For the duration of clinical manifestations. The following forms of AF are distinguished:
- Paroxysmal (paroxysmal). Single episodes of AF, lasting no more than 48 hours in the case of cardioversion, or up to 7 days in the case of spontaneous recovery of the rhythm.
- Persistent form. Atrial fibrillation episodes lasting more than 7 days without spontaneous recovery, or fibrillation amenable to cardioversion (drug or electrical) after 48 hours or more.
- Permanent form(chronic). Continuous AF, which is not amenable to cardioversion, should the doctor and patient decide to abandon attempts to restore sinus rhythm.
By heart rate
- Tachysystolic. Atrial fibrillation with a ventricular rate of more than 90-100 beats. in minutes
- Normosystolic. The AV node allows the ventricles to contract with a frequency of 60–100 beats / min.
- Bradysystolicheskaya. The heart rate in this form of atrial fibrillation does not reach 60 beats / min.
Types of Atrial Fibrillation (AI)
The term atrial fibrillation can refer to the following two types of supraventricular tachyarrhythmias.
Fibrillation (atrial fibrillation). Normally, an electrical impulse occurs in the sinus node (in the wall of the right atrium), spreads through the myocardium of the atria and ventricles, causing their sequential reduction and release of blood. With AF, the electrical impulse spreads chaotically, causing the atria to flicker, when the myocardial fibers contract in an inconsistent and very fast manner. As a result of the chaotic transmission of excitation to the ventricles, they contract non-rhythmically and, as a rule, are not effective enough.
Atrial flutter. In this case, the contraction of the myocardial fibers occurs at a slower pace (200–400 beats per minute). In contrast to AF, atrial flutter is still reduced. As a rule, due to the period of refractoriness of the atrioventricular node, not every electrical impulse is transmitted to the ventricles, so they are not reduced at such a fast pace. However, as with fibrillation, atrial flutter, the pumping function of the heart is disturbed, and the myocardium is under additional stress.
Complications of atrial fibrillation
According to the latest data, patients with atrial fibrillation are at risk not only for the development of thromboembolic stroke, but also myocardial infarction. The mechanisms of damage are as follows: with atrial fibrillation, a full atrial contraction is impossible, therefore blood in them stagnates and thrombi are formed in the atrial wall space. If such a blood clot enters the aorta and into smaller arteries, a thromboembolism of an artery feeds an organ: brain, heart, kidney, intestine, lower limbs. Cessation of blood supply causes a heart attack (necrosis) of the site of this organ. Cerebral infarction is called ischemic stroke. The most common complications are:
- Thromboembolism and stroke. Most often, the target is the brain (in direct carotid arteries, a thrombus “shoots” quite easily in this direction). According to statistics, every fifth patient with a stroke has atrial fibrillation in history.
- Chronic heart failure. Atrial fibrillation and flutter can cause an increase in symptoms of circulatory failure, right up to attacks of cardiac asthma (acute left ventricular failure) and pulmonary edema.
- Dilated cardiomyopathy. The tachysystolic form of MA, when the frequency of ventricular contractions constantly exceeds 90 beats, quickly leads to the pathological expansion of all heart cavities.
- Cardiogenic shock and cardiac arrest. In rare cases, an atrial fibrillation or flutter with marked hemodynamic disturbances can lead to arrhythmogenic shock – a life-threatening condition.
The following directions of drug therapy for atrial fibrillation are distinguished: cardioversion (restoration of normal sinus rhythm), prevention of recurrent paroxysms (episodes) of supraventricular arrhythmias, control of the normal frequency of ventricular contractions of the heart. Also an important goal of medical treatment for AI is the prevention of complications – various thromboembolism. Drug therapy is conducted in four directions.
Antiarrhythmic treatment. It is used if a decision has been made to attempt drug-induced cardioversion (rhythm recovery with medication). Drugs of choice – propafenone, amiodarone.
Propafenone – one of the most effective and safe drugs used to treat supraventricular and ventricular cardiac arrhythmias. The effect of propafenone begins 1 hour after ingestion, the maximum concentration in the blood plasma is reached after 2–3 hours and lasts 8–12 hours.
HR control. If it is impossible to restore a normal rhythm, it is necessary to bring the atrial fibrillation into normal form. Beta-blockers, calcium antagonists of the non-dihydropyridine series (the verapamil group), cardiac glycosides, etc. are used for this purpose.
Beta blockers. Drugs of choice for monitoring the work of the heart (frequency and strength of contractions) and blood pressure. The group blocks beta-adrenergic receptors in the myocardium, causing a pronounced antiarrhythmic (decrease in heart rate), as well as the hypotensive (decrease in blood pressure) effect. Beta blockers have been proven to statistically increase life expectancy for heart failure. Among the contraindications to receive – bronchial asthma (since the blocking of beta 2 receptors in the bronchi causes bronchospasm).
Anticoagulant therapy. To reduce the risk of thrombosis in persistent and chronic forms of AF, blood thinning medications are required. Assign direct anticoagulants (heparin, fraxiparin, fondaparinux, etc.) and indirect (warfarin) action. There are regimens of taking indirect (warfarin) and the so-called new anticoagulants – antagonists of blood coagulation factors (Pradax, Xarelto). Treatment with warfarin is accompanied by mandatory monitoring of clotting indicators and, if necessary, careful correction of the dosage of the drug.
Metabolic therapy. Metabolic drugs include drugs that improve nutrition and metabolic processes in the heart muscle. These drugs allegedly have a cardioprotective effect, protecting the myocardium from the effects of ischemia. Metabolic therapy for AI is considered an additional and optional treatment. According to the latest data, the effectiveness of many drugs is comparable to placebo. These drugs include:
- ATP (adenosine triphosphate);
- K and Mg ions;
Diagnosis and treatment of any type of arrhythmia requires considerable clinical experience, and in many cases, high-tech hardware. In atrial fibrillation and atrial flutter, the main task of the doctor is, if possible, to eliminate the cause that led to the development of pathology, preserve heart function and prevent complications.
Symptoms of OP
Depending on the form of the arrhythmia (constant or paroxysmal) and the patient’s susceptibility, the clinical picture of AF varies from the absence of symptoms to the presence of signs of heart failure. Patients may complain of:
- interruptions in the work of the heart;
- “Gurgling” and / or chest pain;
- a sharp increase in heart rate;
- darkening of the eyes;
- general weakness, dizziness (with hypotension);
- fainting or fainting;
- feeling short of breath, shortness of breath and feeling of fear.
Atrial fibrillation and atrial flutter may be accompanied by increased urination caused by increased production of the natriuretic peptide. Attacks that last several hours or days and do not go away on their own require medical intervention.
Pathogenesis and general clinical picture
The main manifestation of atrial fibrillation is an arrhythmic pulse. With a high heart rate at the time of an attack of AF, a pulse deficit may occur when the number of heartbeats exceeds the pulse rate.
Causes of AF and risk factors
Diseases of various origins
Most often, FP occurs in patients with diseases of the cardiovascular system — arterial hypertension, coronary artery disease, chronic heart failure, and heart defects — congenital and acquired, inflammatory processes (pericarditis, myocarditis), and heart tumors. Among the acute and chronic diseases that are not related to the pathology of the heart, but affecting the onset of atrial fibrillation, there are thyroid dysfunction, diabetes mellitus, chronic obstructive pulmonary disease, sleep apnea syndrome, kidney disease, etc.
Atrial fibrillation is called grandparent arrhythmia, since the incidence of this arrhythmia increases dramatically with age. The development of this cardiac rhythm disorder can be promoted by electrical and structural changes in the atria. However, experts note that atrial fibrillation can occur in young people who do not have heart disease: up to 45% of paroxysmal cases and up to 25% of persistent fibrillation cases.
Other risk factors
Atrial fibrillation can develop against the background of alcohol use, after an electric shock and open heart surgery. Paroxysms can provoke factors such as physical exertion, stressful conditions, hot weather, and abundant drinking. In rare cases, there is a genetic predisposition for the onset of AF.
First you need to determine the individual risk of stroke:
Determining the risk of stroke in primary * (if there has not been a stroke before) prevention (J Am Coll Cardiol 2001; 38: 1266i-1xx).