Supraventricular tachycardia.

Supraventricular or supraventricular tachycardia refers to a type of cardiac arrhythmia caused by primary disorders with the regulation of the heart rate (more than one hundred beats per minute), problems with the conduction of electrical impulses.

A similar disease is found in children and is often a hereditary, genetic pathology.

The following types of supraventricular tachycardia are distinguished:

• atrial;
• arrhythmia associated with WPW syndrome;
• atrial flutter;
• atrioventricular nodal disorder.

Such arrhythmias are diseases bordering between potentially dangerous (sometimes fatal) and benign deviations from the heart rhythm norm. Doctors often note a favorable course of this tachycardia.

Causes of supraventricular tachycardia

The prerequisites for the development of functional tachycardia in adolescence and childhood are considered to be: anxiety, strong emotions, nervous tension, stress.

In adult patients, cardiac arrhythmia develops against the background of nervous disorders and unstable emotional state. Often, arrhythmia is provoked by climacteric changes, neurasthenia, contusion, neurocirculatory disorders. Failures in the functioning of the gastrointestinal tract, kidneys, gall bladder and diaphragm can also become a trigger mechanism that negatively affects the work of the heart muscle. Some pharmacological drugs, such as quinidine or novocainamide, can provoke an attack. An overdose of glycosides is very dangerous, which can lead to the death of the patient.

The causes of supraventricular tachycardia are hidden in concomitant heart diseases, which often precede the onset of attacks. Thus, in younger patients, the pathology may indicate a congenital defect of the conduction pathways - Wolff-Parkinson-White syndrome. Protracted, frequently recurring infections, hypertension and thyrotoxicosis are factors that provoke the pathological condition.

The presence of negative addictions, which include smoking, drinking alcohol, caffeine, and drugs, significantly increases the risk of tachycardia.

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Symptoms of supraventricular tachycardia

An attack of tachycardia, lasting up to several hours, is characterized by a fast and even heartbeat. People of any age group are susceptible to the disease, but the pathology is most often diagnosed in childhood or adolescence.

Typically, symptoms of supraventricular tachycardia occur suddenly. These include:

• acceleration of cardiac contractility;
• pain syndrome (tightness) in the neck or chest area;
• dizziness;
• fainting;
• feeling of anxiety, panic attacks.

Long-term attacks cause signs of cardiovascular failure: swelling, pale-blue areas of skin on the face, arms or legs, problems with inhalation. A decrease in blood pressure is another sign of tachycardia. People with low blood pressure, in turn, are most susceptible to the occurrence of this arrhythmia. This is due to the fact that the body of a hypotonic person tries to normalize blood flow to the organs by increasing the number of heart contractions.

Quite often the disease develops asymptomatically. But even episodic attacks have a negative effect on the entire body, which is associated with insufficient blood supply to the organs due to its ineffective pumping by the heart muscle.

The danger appears only with concomitant heart diseases. Due to the suddenness of the attacks, the patient's quality of life is significantly reduced. The patient is in constant tension, not knowing when the next deterioration of the condition will occur and how severe it will be.

Paroxysmal supraventricular tachycardia

Paroxysmal tachycardia is a sudden increase in the heart rate (150-300 beats per minute), observed in the upper sections. Attacks are associated with a disturbance in the circulation of the impulse or the appearance of zones in the heart muscle that provoke tachycardia. As a rule, young people are more susceptible to pathology. Moreover, sudden malaise can disappear on its own after a few seconds or days.

Paroxysmal supraventricular tachycardia may have the following symptoms:

• a spontaneous, sharp increase in heart rate that goes away on its own;
• discomfort in the heart area;
• rapid fatigue, weakness;
• the appearance of shortness of breath;
• a state of unreasonable anxiety;
• signs of nausea;
• dizziness, possible fainting;
• frequent urge to urinate.

Cardiac and extracardiac causes of the disease are distinguished. Among cardiac factors are:

• defects/features of a congenital nature (appear during intrauterine development);
• problems with decreased contractile activity (heart failure);
• acquired defects (changes in structure) of the heart;
• history of inflammation (myocarditis) or abnormal structure and function (cardiomyopathy) of the heart muscle.

Non-cardiac diseases:

• endocrine pathologies;
• pulmonary embolism;
• bronchopulmonary diseases;
• disorders of the autonomic nervous system.

Paroxysmal pathology can be provoked by a number of negative habits, namely:

• impact of stress;
• abuse of tobacco and alcohol;
• excessive physical exertion;
• caffeine consumption.

Paroxysm of supraventricular tachycardia

Paroxysm of supraventricular tachycardia is formed in case of location of the pathology focus in the area of the atria or atrioventricular junction. Moreover, attacks of arrhythmia do not occur regularly, but only under the influence of irritating factors.

The paroxysm is realized by two mechanisms:

• detection of the excitation center in the atrial tissues. The pulse rhythm in the sinus node is lower, so normal contractile activity is replaced by pathological;
• there are problems associated with changes in the structure of the conduction system. The presence of additional pathways for the passage of a nerve excitatory impulse, forming Re-entry - a clear cause of paroxysmal tachycardia.

The causes of the pathological condition are:

• activation of nervous excitability as a result of fear, stress;
• hypersensitivity of cardiac muscle receptors to the group of catecholamines;
• presence of heart defects;
• congenital disorders with the structure of the conduction pathways;
• organic dysfunctions (infection, dystrophy, ischemia);
• changes due to toxic effects from drugs, alcohol and other substances.

Supraventricular tachycardia runs

Supraventricular tachycardia runs are divided into:

• bigeminy - alternation of one extrasystole and one rhythm of contractions;
• bigeminy and aberrant extrasystole - block of the bundle branch of His on the right or the so-called V1, V2 ears;
• trigeminy – repetition of two QRS complexes with one extrasystole;
• intercalary extrasystole – an increase in the PQ segment following an extrasystole, which has some differences from the normal values of adjacent complexes;
• blocked extrasystole - the end of the T-wave on the second complex shows the premature appearance of the P-wave, but due to refractoriness, excitation is not carried out on the ventricles;
• a series of extrasystoles of the bigeminy type - the P-wave following the T-wave of the previous complex is visible on the cardiogram.

Diagnosis of supraventricular tachycardia

The disease can be suspected based on the patient's complaints, who notes primary disturbances in the heart, shortness of breath, a pressing feeling in the chest, does not tolerate exercise well and is perplexed by constant weakness, nausea, dizziness. The doctor supplements the anamnesis with information about cardiac pathologies in close relatives and cases of sudden death during physical activity.

Diagnosis begins with a physical examination that reveals excess body weight, skin problems, and blood pressure surges. Laboratory tests of blood and urine are mandatory. A blood biochemistry test provides information about cholesterol and triglyceride levels, sugar and potassium content.

The main diagnostic tool for supraventricular tachycardia is electrocardiography. Daily monitoring of the heart muscle activity using a cardiogram records attacks (including the onset and end of the pathological condition) that the patient does not feel, and allows one to assess the nature and severity of the arrhythmia.

The method of transesophageal cardiac stimulation serves to clarify the development of paroxysmal tachycardia, as well as to differentiate pathology in patients with rare attacks that are not recorded by the electrocardiogram.

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Supraventricular tachycardia on ECG

Re-entry in the AV node zone (nodal reciprocal arrhythmia) accounts for more than half of the cases of supraventricular tachycardia. Supraventricular tachycardia on the ECG, as a rule, does not give QRS deformation. Often, Re-entry of the atrioventricular node entails an increase in heart rate. Moreover, a tachycardic attack is characterized by simultaneous excitation of the ventricles and atria, and the P-teeth are combined with the QRS and are invisible on the cardiogram. With a block on the atrioventricular node itself, Re-entry interrupts the impulse. Blockade of the His bundle or below it does not affect tachycardia. Such blocks are rare even in young patients.

Arrhythmia in the sinus node re-entry region is not common. In this case, the P-waves of the arrhythmia and the sinus curve coincide in shape.

A small percentage of tachycardias are due to atrial re-entry. The P wave is seen ahead of the QRS complex, indicating anterograde transmission between the atria.

Treatment of supraventricular tachycardia

Treatment of supraventricular tachycardia is carried out conservatively and surgically. Conservative therapy includes:

• prevention of tachycardia by taking antiarrhythmic drugs prescribed by a cardiologist;
• stopping attacks by intravenous administration of antiarrhythmic drugs or by electro-impulse action.

Antiarrhythmic drugs and glycosides are prescribed as maintenance anti-relapse therapy. The dosage and the drug itself are determined empirically, taking into account the effectiveness, toxicity and pharmacokinetic characteristics of the drug. Paroxysmal heart rhythm disturbances are treated with amiodarone only if other drugs are ineffective, taking into account side effects. Sotalol, diltiazem, etacizine, quinidine, verapamil, etc. are suitable for long-term maintenance therapy.

Indications for surgical intervention are:

• increased frequency of attacks and their severity;
• the presence of tachycardia even when taking special medications;
• professional activity is associated with a health risk resulting from loss of consciousness;
• conditions in which drug therapy is not possible (e.g. young patients).

Surgical treatment is understood as a method of radiofrequency ablation, i.e. recognition and elimination of the source of pathology. For this purpose, an electrode is inserted into a large vein and the pathological focus is treated with high-frequency current. If there are several areas, the procedure is repeated. The therapy is expensive and has a number of complications, including disruption of the ventricles or atria, which will require the installation of a pacemaker. But even this does not stop patients who are in constant fear of another attack.

Termination of supraventricular tachycardia

Severe arrhythmia with frequent attacks requires hospital treatment, where antiarrhythmic agents and oxygen are administered. Particularly difficult cases are amenable to therapy with electropulse and radiofrequency exposure, normalizing the heart rhythm.

Short-term supraventricular tachycardia can be stopped independently by massaging the neck area above the carotid artery. As practice shows, rubbing movements stimulate the vagus nerve, thereby allowing control of the heart rate. Patients over 50 years of age should not fight an attack without qualified help (there is a high risk of stroke). Washing with ice water followed by straining, as during defecation, throwing the head back, an ice collar on the neck and pressure on the eyeballs can also stop an attack of tachycardia.

It should be noted that in order to massage the neck and press on the eyes, a person must have medical skills, since incorrect execution can be quite traumatic.

It is recommended to start drug-based seizure control with beta-blockers (bisoprolol, atenolol, etc.). If the drug is ineffective, it is not advisable to use a drug from the same group. Combinations of beta-blockers with antiarrhythmic agents are often used. Such therapy allows to reduce the dosage of active components while maintaining the effectiveness of treatment.

Emergency care for supraventricular tachycardia

Emergency care for supraventricular tachycardia involves the following measures:

• provoking the gag reflex;
• compression of the right carotid ganglion;
• pressure on the eyeballs;
• straining while taking a deep breath with your nose pinched;
• pressing on the abdomen from above;
• pressing bent legs to the stomach;
• cold rubdowns;
• use of sedatives (tincture of motherwort/valerian, valocordin, diazepam in quantities proportionate to the patient’s age);
• If there is no effect from the listed methods, antiarrhythmic drugs are used after an hour.

An attack of tachycardia is relieved with verapamil intravenously (dosage 0.005 g), then outside the attack take one tablet (0.04 g) two or three times a day. If verapamil does not help, then β-blockers are recommended: visken, anaprilin or oxprenolol. The lack of effect from drugs requires the use of electrical cardiac stimulation or defibrillation.

Urgent hospitalization is indicated if an attack of tachycardia entails:

• loss of consciousness;
• hemodynamic abnormalities;
• manifestations of ischemic disorders.

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Prevention of supraventricular tachycardia

When a trigger for a tachycardia attack is detected, it is sometimes enough to eliminate it in order to prevent repeated disturbances in heart rhythm. For example, caffeine, alcohol, and smoking can be factors that cause tachycardia. Eliminating these addictions, as well as reducing physical activity and eliminating the effects of stress, reduces the risk of repeated relapses or completely rids the patient of cardiac arrhythmia.

Antiarrhythmic prophylaxis of supraventricular tachycardia according to the type of pathology:

• radiofrequency ablation (RFA) is a method for preventing asymptomatic arrhythmia or focal atrial arrhythmia with Wolff-Parkinson-White syndrome, ectopic atrioventricular nodal tachycardia, as well as unstable atrial arrhythmia;
• diltiazem, verapamil - drugs recommended for prophylactic purposes for paroxysmal reciprocal atrioventricular nodal arrhythmia;
• β-blockers – used for poorly tolerated tachycardia, ectopic atrioventricular nodal, atrial, symptomatic paroxysmal reciprocal arrhythmia;
• Amiodarone is a prophylactic drug in cases of nodal tachycardia of the paroxysmal reciprocal atrioventricular type, resistant to β-blockers or verapamil.

Prognosis of supraventricular tachycardia

Complications of the disease may include dysfunction of blood circulation in tissues, heart failure, pulmonary edema (the heart cannot cope with pumping blood, which causes the lungs to fill up), and an attack of angina pectoris (as a result of a decrease in the value of cardiac output with a decrease in coronary blood flow).

The prognosis of supraventricular tachycardia is based on the underlying disease, the frequency and duration of the attack, the presence of complications during the attack, and the characteristics of the myocardium.

For example, physiological sinus arrhythmia is not dangerous and has a favorable course. The presence of concomitant heart pathologies, in turn, aggravates the pathological picture and the outcome of the disease can be serious.

The disease allows patients to lead a normal life. Rare attacks pass on their own or with medication. The worst prognosis is for frequently recurring tachycardias, which lead to disruption of the nervous system, impairing performance, and often making a person disabled.