Arrhythmia is any violation of the regularity or frequency of the normal heart rhythm, as well as the electrical conductivity of the heart. Arrhythmia may be asymptomatic or be felt in the form of palpitations, fading or interruptions in the work of the heart. Sometimes arrhythmias are accompanied by dizziness, fainting, heart pain, a feeling of lack of air. Arrhythmias are recognized during physical and instrumental diagnostics (cardiac auscultation, ECG, ECG, Holter monitoring, stress tests). In the treatment of various types of arrhythmias, drug therapy and cardiac surgery methods are used (RF, installation of an electrocardiostimulator, cardioverter defibrillator).
The term "arrhythmias" combines various mechanisms of occurrence, manifestations and prognosis of disorders of the origin and conduction of electrical impulses of the heart. They arise as a result of violations of the conduction system of the heart, which provides consistent and regular contractions of the myocardium - sinus rhythm. Arrhythmias can cause severe disorders of the heart or the functions of other organs, as well as themselves be complications of various serious pathologies. According to statistics, conduction and heart rhythm disorders are the cause of death from heart disease in 10-15% of cases. The study and diagnosis of arrhythmias is carried out by a specialized section of clinical cardiology - arrhythmology.
According to the causes and mechanism of arrhythmia, they are conditionally divided into two categories: those related to cardiac pathology (organic) and those not related to it (inorganic or functional). The group of functional arrhythmias includes neurogenic, diselectrolytic, iatrogenic, mechanical and ideopathic rhythm disturbances.
Rhythmic sequential contraction of the heart is provided by special muscle fibers of the myocardium, which form the conducting system of the heart. In this system, the driver of the rhythm of the first order is the sinus node: it is in it that excitation originates with a frequency of 60-80 times per minute. Through the myocardium of the right atrium, it spreads to the atrioventricular node, but it turns out to be less excitable and gives a delay, so the atria first contract and only then, as the excitation spreads through the Gis bundle and other parts of the conducting system, the ventricles.
Thus, the conducting system provides a certain rhythm, frequency and sequence of contractions: first the atria, and then the ventricles. The defeat of the conducting system of the myocardium leads to the development of rhythm disturbances (arrhythmias), and its individual links (atrioventricular node, bundle or Gis legs) - to conduction disturbances (blockades). In this case, the coordinated work of the atria and ventricles may be sharply disrupted.
The development of organic arrhythmias is based on damage (ischemic, inflammatory, morphological) to the heart muscle. They make it difficult for the normal propagation of an electrical impulse through the conducting system of the heart to its various departments. Sometimes the damage also affects the sinus node – the main driver of the rhythm. During the formation of cardiosclerosis, scar tissue interferes with the conduction function of the myocardium, which contributes to the occurrence of arrhythmogenic foci and the development of conduction and rhythm disorders.
The etiological, pathogenetic, symptomatic and prognostic heterogeneity of arrhythmias causes discussions about their unified classification. According to the anatomical principle, arrhythmias are divided into atrial, ventricular, sinus and atrioventricular. Taking into account the frequency and rhythmicity of heart contractions, it is proposed to distinguish three groups of rhythm disorders:
The most complete classification is based on the electrophysiological parameters of rhythm disturbance, according to which arrhythmias are distinguished:
Nomotopic arrhythmias are caused by a violation of the automatism function of the sinus node and include sinus tachycardia, bradycardia and arrhythmia. Separately, sinus node weakness syndrome (SSS) is distinguished in this group.
Heterotopic arrhythmias are characterized by the formation of passive and active ectopic complexes of myocardial excitation located outside the sinus node.
In passive heterotopic arrhythmias, the occurrence of an ectopic pulse is caused by a slowdown or disruption of the main pulse. Passive ectopic complexes and rhythms include atrial, ventricular, atrioventricular junction disorders, migration of the supraventricular pacemaker, popping contractions.
With active heterotopias, the resulting ectopic pulse excites the myocardium before the pulse formed in the main driver of the rhythm, and ectopic contractions "interrupt" the sinus rhythm of the heart. Active complexes and rhythms include: extrasystole (atrial, ventricular, originating from the atrioventricular junction), paroxysmal and nonparoxysmal tachycardia (originating from the atrioventricular junction, atrial and ventricular forms), fluttering and flickering (fibrillation) of the atria and ventricles.
The manifestations of arrhythmias can be very different and are determined by the frequency and rhythm of heart contractions, their effect on intracardiac, cerebral, renal hemodynamics, as well as the function of the myocardium of the left ventricle. There are so-called "mute" arrhythmias that do not manifest themselves clinically. They are usually detected by physical examination or electrocardiography.
The main manifestations of arrhythmias are palpitations or a feeling of interruptions, fading when the heart is working. The course of arrhythmias may be accompanied by suffocation, angina, dizziness, weakness, fainting, and the development of cardiogenic shock. Palpitations are usually associated with sinus tachycardia, attacks of dizziness and fainting – with sinus bradycardia or sinus node weakness syndrome, cardiac arrest and discomfort in the heart area – with sinus arrhythmia.
With extrasystole, patients complain of feelings of fading, pushing and interruptions in the work of the heart. Paroxysmal tachycardia is characterized by suddenly developing and stopping heart palpitations up to 140-220 beats. in min. The sensation of a frequent, irregular heartbeat is noted with atrial fibrillation.
The course of any arrhythmia can be complicated by fibrillation and fluttering of the ventricles, which is equivalent to stopping blood circulation, and lead to the death of the patient. Already in the first seconds, dizziness, weakness develop, then loss of consciousness, involuntary urination and convulsions. Blood pressure and pulse are not determined, breathing stops, pupils dilate – a state of clinical death occurs. In patients with chronic circulatory insufficiency (angina pectoris, mitral stenosis), shortness of breath occurs during paroxysms of tachyarrhythmia and pulmonary edema may develop.
With complete atrioventricular blockade or asystole, syncopal states may develop (Morgagni-Adams-Stokes attacks characterized by episodes of loss of consciousness) caused by a sharp decrease in cardiac output and blood pressure and a decrease in blood supply to the brain. Thromboembolic complications with atrial fibrillation in every sixth case lead to a cerebral stroke.
The primary stage of the diagnosis of arrhythmia can be carried out by a therapist or a cardiologist. It includes the analysis of patient complaints and the determination of the peripheral pulse characteristic of cardiac arrhythmias. At the next stage, instrumental non-invasive (ECG, ECG monitoring), and invasive (NPEFI, VEI) research methods are carried out:
The choice of therapy for arrhythmias is determined by the causes, type of rhythm and conduction disorders of the heart, as well as the patient's condition. In some cases, it is enough to treat the underlying disease to restore the normal sinus rhythm.
Sometimes, special medication or cardiac surgery is required to treat arrhythmias. The selection and appointment of antiarrhythmic therapy is carried out under systematic ECG control. According to the mechanism of action , there are 4 classes of antiarrhythmic drugs:
Non-drug treatments for arrhythmias include electrocardiostimulation, implantation of a cardioverter defibrillator, radiofrequency ablation and open-heart surgery. They are performed by cardiac surgeons in specialized departments.
Implantable antiarrhythmic devices. Implantation of an electrocardiostimulator (EX) – an artificial pacemaker is aimed at maintaining a normal rhythm in patients with bradycardia and atrioventricular blockades. The implanted cardioverter-defibrillator for preventive purposes is sewn to patients who have a high risk of sudden occurrence of ventricular tachyarrhythmia and automatically performs pacing and defibrillation immediately after its development.
Radiofrequency ablation. With the help of the RF of the heart, through small punctures with the help of a catheter, cauterization of the area of the heart generating ectopic impulses is carried out, which allows blocking impulses and preventing the development of arrhythmia.
Open operations. Open-heart surgery is performed for cardiac arrhythmias caused by left ventricular aneurysm, heart valve defects, etc.
In prognostic terms, arrhythmias are extremely ambiguous. Some of them (supraventricular extrasystoles, rare ventricular extrasystoles), not related to organic pathology of the heart, do not pose a threat to health and life. Atrial fibrillation, on the contrary, can cause life-threatening complications: ischemic stroke, severe heart failure. The most severe arrhythmias are fluttering and ventricular fibrillation: they pose an immediate threat to life and require resuscitation.
The main direction of prevention of arrhythmias is the treatment of cardiac pathology, which is almost always complicated by a violation of the rhythm and conduction of the heart. It is also necessary to exclude extracardial causes of arrhythmia (thyrotoxicosis, intoxication and feverish states, autonomic dysfunction, electrolyte imbalance, stress, etc.). It is recommended to limit the intake of stimulants (caffeine), the exclusion of smoking and alcohol, self-selection of antiarrhythmic and other drugs.