Arrhythmia is a private form of ischemic heart disease, which is manifested by violations of the rhythmicity, sequence and frequency of contraction. For convenience of study and differentiation, these diseases are divided into two groups: tachyarrhythmias and bradyarrhythmias. But more convenient is the classification according to the type of violation of the function of the conducting system of the heart.
- Violations of nodal automatism: sinus arrhythmia, bradycardia, tachycardia, SA-node weakness syndrome, ectopic idioventricular, inferior atrial and nodal (AV) rhythms.
- Violation of excitability of atypical myocytes: paroxysmal tachycardias, atrial, ventricular and nodal extrasystoles.
- Violation of impulse conduction: intraventricular, sinoatrial, atrioventricular block, WPW syndrome.
- Mixed arrhythmias: atrial fibrillation and atrial and ventricular flutter.
This principle of arrhythmia grouping is the basis of the international classification and allows competent assessment of risk factors, identification of specific causes and treatment approaches.
Groups of causes of arrhythmias
Causes are divided into cardiac, toxic, drug and electrolyte. Among cardiac causes, ischemic heart disease, malformations, cardiomyopathy, myocarditis are the most important. These pathologies are characterized by the presence of a defect in the structure of the myocardium and the conduction system of the heart. For this reason, the impulse is either slowed down, blocked, or re-excites the myocardial area. This mechanism is characteristic of blockades, atrial fibrillation, atrial or ventricular flutter, and paroxysmal tachycardias.
Toxic causes of arrhythmias are due to the influence of alcohol, atropine, organophosphorus compounds. Thyrotoxic goiter, alcohol or atropine poisoning result in sinus tachycardia, whereas myxedema and FOS poisoning result in sinus bradycardia and sinus node weakness syndrome. Rhythm disturbance is sometimes a side effect of groups of drugs: antiarrhythmics, diuretics, adrenomimetics, cardiac glycosides. Slightly less often the cause of arrhythmia is hypo- and hyperkalemia, hypercalcemia, hypomagnesemia.
Symptoms of arrhythmias
The clinical signs of arrhythmias depend on the specific type of arrhythmia. Symptoms of tachyarrhythmias include palpitations, a feeling of tightness or burning behind the sternum, mixed dyspnea, facial hyperemia, and sweating. The patient may note increased and rapid pulsation on the carotid artery in sinus tachycardia and, conversely, weakening of the pulse with a drop in blood pressure in atrial fibrillation, atrial flutter or ventricular flutter, conduction blockades in various areas.
Bradyarrhythmias are manifested by rapid-onset weakness in the legs, dizziness, headache, darkening of the eyes, a feeling of freezing of the heart, a drop in blood pressure. Loss of consciousness is rare, but is specific for sinoatrial and atrioventricular block of II and III degrees, for atrial fibrillation, atrial flutter or ventricular flutter.
Some arrhythmias are not apparent in most patients until they result in hemodynamic disturbances: extrasystoles, WPW syndrome, atrial flutter and paroxysmal tachycardia, and various types of grade I block. Ventricular extrasystole is sometimes accompanied by a single strong contraction of the heart followed by freezing for 1-4 seconds. Insertion ventricular, atrial, or nodal extrasystole may not occur at all without jeopardizing well-being.
Arrhythmias are diagnosed on the basis of patient complaints, medical history, auscultation and electrocardiography. Complaints will suggest the type of arrhythmia and its duration. Auscultation allows to suspect an arrhythmia that is not symptomatic. ECG can be used to recognize the type of arrhythmia and determine its degree, to clarify the source of ectopic rhythm and the presence of an additional conduction pathway, to suspect morphologic changes in the myocardium. This information is required for the choice of treatment tactics and evaluation of its success. The technique of daily ECG recording – Holter monitoring – is also used.
Effective treatment of arrhythmia
Treatment of arrhythmia consists of two directions: management of emergency arrhythmic conditions and preventive therapy. The first direction of treatment involves the use of drugs from the group of sodium channel blockers. The most commonly used are flecainide, propafenone, procainamide. Treatment of urgent arrhythmias can also involve the use of cardiac glycosides. For example, the treatment of atrial fibrillation begins with the intravenous administration of digoxin or strophanthine. Less commonly, calcium channel blockers are used in atrial paroxysms.
Emergency arrhythmias can be eliminated with the help of hardware methods – cardioversion and defibrillation. Indications for these measures are: paroxysmal atrial or ventricular fibrillation and flutter. Defibrillation tactics depend on the specific type of arrhythmia, as well as the rate at which sinus rhythm is restored.
Preventive therapy is the second line of treatment needed to reduce the incidence of emergencies. Supportive therapy of arrhythmias is realized through a course of antiarrhythmics from the group of potassium channel blockers (amiodarone), beta-adrenoblockers, calcium antagonists. At the same time, treatment is prescribed only for those arrhythmias due to which there is a disturbance of blood circulation. If the arrhythmia does not violate the vital activity of a person, then it should not be treated. The reason for this is the high risk of developing a new arrhythmia due to taking the drug. Proarrhythmogenic action is characterized by all antiarrhythmics, especially sodium channel blockers. In the case of bradyarrhythmias and complete blockages of the conducting system, which are accompanied by a significant drop in blood pressure, implantation of a temporary and then a permanent pacemaker is used. It sets its own rhythm of the heart, allowing a person to maintain vital activity at a functional level. In this case, the patient who has a pacemaker, the use of antiarrhythmics is not indicated.