Symptoms and Diagnosis of Supraventricular Tachyarrhythmias

Symptoms of chronic sinus tachycardia are a feeling of palpitation, which increases with exercise. This arrhythmia is typical for school-age children, it is often met during puberty. Despite the constantly increasing heart rate (100-140 per minute), children experience palpitations with emotional and physical exertion. Other symptoms include sleep disturbances, sleep and sleep, neurotic reactions, tics, stammering, increased sweating of the palms and feet. Girls suffer this type of rhythm disturbance 3 times more often than boys. In ECG, craniocaudal (sinus) morphology of the R wave is recorded . Chronic sinus tachycardia should be differentiated from heterotopic tachycardia from the upper part of the right atrium, in which, as a rule, there are no complaints of palpitation and the rigidity of the rhythm.

With extrasystole and non-paroxysmal supraventricular tachycardia, children rarely make complaints, as a result of which these types of arrhythmias are detected accidentally during preventive examinations, examinations when referring to the sports section, about intercurrent diseases. The term "non-paroxysmal tachycardia" implies the presence of a constantly increased heart rate. From paroxysmal tachycardia, this rhythm disturbance is distinguished by a constant arrhythmia, as well as the absence of a sudden onset and end of an attack. Frequent rhythm can persist for a long time, for weeks, months, years. There are cases when tachycardia lasted for decades. Nonspecific complaints of asthenovegetative nature reflect the dysfunction of the parasympathetic part of the autonomic nervous system: rapid fatigue, sleep disturbances, headaches, sudden attacks of weakness, dizziness, poor transport tolerance, cardialgia. 70% of children report a delay in motor development and puberty. Heredity in the first generation is burdened by autonomic dysfunction with a predominance of parasympathetic effects on the cardiovascular system: in 85% of families, one of the parents has arterial hypotension, bradycardia or AV blockade of the first degree.

With non-paroxysmal supraventricular tachycardia of recurrent type, the rhythm frequency during a tachycardia attack ranges from 110 to 170 per minute. The average duration of seizures of non-paroxysmal supraventricular tachycardia of recurrent type is about 30 s, it can reach several minutes. With non-paroxysmal supraventricular tachycardia of a permanent type, a regular (rigid) rhythm of constant frequency (130-180 per minute) with a narrow ventricular complex is recorded. The rhythm of cardiac contractions with non-paroxysmal supraventricular tachycardia, as a rule, is rigid, but with a more "slow" tachycardia, the variation range of the RR intervals increases. A negative correlation was found between the duration of an attack of tachycardia and heart rate in it. With prolonged existence, non-paroxysmal supraventricular tachycardia is complicated by the development of arrhythmogenic myocardial dysfunction leading to arrhythmogenic cardiomyopathy with cavitation dilatation. When the sinus rhythm is restored within a few weeks, the dimensions of the heart cavities return to the age norm. Clinico-electrocardiographic criteria for the risk of arrhythmogenic cardiomyopathy for various forms of non-paroxysmal supraventricular tachycardia in children without organic heart disease are as follows:

• dezadaptive left ventricular myocardial response to tachycardia according to EchoCG;
• the average heterotopic rhythm frequency is more than 140 per minute;
• low representation of sinus rhythm in the daily volume of cardiocycles (less than 10% according to holter monitoring);
• violation of synchronization of the atrioventricular contractions, marked with AB-dissociation, atrial fibrillation-flutter.

Paroxysmal form of supraventricular tachycardia is characterized by a sudden sudden onset of arrhythmia, almost always the child feels it as a palpitations. In 15% of patients at the time of the attack, pre-syncopal or syncopal conditions develop. More than 60% of cases of relapses of paroxysmal tachycardia occur in a certain period of the day (circadian seizures). The most unfavorable course with frequent relapses and longer attacks of tachycardia is typical for evening and night attacks of supraventricular tachycardia. Among the features of the clinical picture in older children is the high frequency of sleep disorders and the abundance of vegetative complaints, meteorological sensitivity. The most common debut of tachycardia occurs at the age of 4-5 years, characterized by an increased level of psycho-vegetative excitability, accelerated growth of heart structures and restructuring of circadian regulation of the cardiovascular system.

Instrumental methods

Electrocardiographic diagnosis allows in most cases to differentiate the types of supraventricular tachycardia. A typical (slow-fast) AV nodal reciprocal tachycardia characterizes attack beginning with extrasystoles with extended intervals PR, during a seizure recorded narrow complex QRS, P wave often visualized or retrogrades (negative in leads II, III, and aVF) interval RP less than 100 ms. For this arrhythmia paroxysmal form is characteristic. Atypical tachycardia is characterized by a slower retrograde exercise, it often has a non-paroxysmal course. This arrhythmia often leads to the development and subsequent progression of diastolic dysfunction of the myocardium. In addition, it was noted that in the presence of a long arrhythmic anamnesis, other types of supraventricular arrhythmias, such as atrial fibrillation, also join, which significantly worsens the prognosis of the disease.

Orthodromic AV-reciprocal tachycardia is characterized by a narrow complex of QRS, slowing of heart rate with the development of blockade of the legs of the bundle. Presence of depression of the ST segment and inversion of the T wave . The R-P interval is usually greater than 100 ms. Sometimes an alternative to the ventricular complex is possible in terms of amplitude. Antidromic tachycardia is characterized by a wide complex of QRS. In the manifest form of Wolff-Parkinson-White syndrome (the most frequent variant of antidromic tachycardia in children), antegrade conduction is carried out along a bundle of Kent. There is evidence of an increased incidence of the syndrome among patients with Ebstein's anomaly, tricuspid atresia, hypertrophic cardiomyopathy. On an ECG without an attack of tachycardia, the criteria for the syndrome are as follows:

• Shortening of the PR interval is less than 120 ms;
• the presence of a delta wave in front of the QRS complex;
• The QRS complex expansion is more than 100 ms;
• secondary changes in the ST-T interval .

By the polarity of the delta wave and the morphology of the QRS complex, the estimated localization of the additional conducting path is determined. The most unfavorable from the perspective of the electrophysiological prognosis is the possibility of carrying high-frequency pulses to the ventricles, which causes a high risk of developing ventricular fibrillation.

Atrial tachycardia is characterized by an abnormal morphology of the P wave, preceding the appearance of the ventricular complex of normal morphology. Often, a functional AV blockade is recorded. Ectopic tachycardias are quite persistent, poorly amenable to drug treatment, a rigid atrial rhythm often leads to the development of myocardial dysfunction. Multifocus (chaotic) atrial tachycardia is characterized by an irregular atrial rhythm of more than 100 per minute with a variable polymorphic (not less than three different variants) morphology of the P wave. The isoelectric line between the P-waves and various intervals of P-P, PR and RR are recorded.

Atrial flutter is an atrial re-entry-tachycardia with a frequency of 250-350 per minute. A typical atrial flutter is due to the circulation of the excitation wave through a certain anatomical zone - the isthmus between the mouth of the inferior vena cava and the fibrous ring of the tricuspid valve. This type of atrial flutter is rarely seen in childhood. It is characterized by a regular tooth P with a frequency of 250-480 per minute, absence of an isoline between the teeth P (sawtooth curve), variability of AB-conduction (most often from 2: 1 to 3: 1). In atrial fibrillation, disorganized atrial activity is recorded at a frequency of up to 350 per minute (wave f), which is more often detected in leads V1 and V2. Ventricular contractions are irregular due to the variability of AB-conduction.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]