Symptoms and diagnosis of supraventricular tachyarrhythmias

Symptoms of chronic sinus tachycardia include a feeling of palpitations, which intensify with exertion. This arrhythmia is typical for school-age children and is often encountered during puberty. Despite the constantly increased heart rate (100-140 per minute), children experience palpitations during emotional and physical stress. Other symptoms include difficulty falling asleep, sleepwalking and sleep talking, neurotic reactions, tics, stuttering, increased sweating of the palms and feet. Girls suffer from this type of rhythm disorder 3 times more often than boys. An ECG records craniocaudal (sinus) morphology of the P wave. Chronic sinus tachycardia should be differentiated from heterotopic tachycardia from the upper part of the right atrium, which, as a rule, is absent from complaints of a feeling of palpitations and reveals rhythm rigidity.

In case of extrasystole and non-paroxysmal supraventricular tachycardia, children rarely present complaints, as a result of which these types of arrhythmia are detected accidentally during preventive examinations, examinations when referring to a sports section, or for intercurrent diseases. The term "non-paroxysmal tachycardia" implies the presence of a constantly rapid heart rhythm. This rhythm disorder differs from paroxysmal tachycardia by constant arrhythmia, as well as the absence of a sudden onset and end of an attack. The rapid rhythm can persist for a long time, for weeks, months, years. There are cases when tachycardia continued for decades. Non-specific complaints of an asthenovegetative nature reflect dysfunction of the parasympathetic division of the autonomic nervous system: rapid fatigue, sleep disorders, headaches, sudden attacks of weakness, dizziness, poor transport tolerance, cardialgia. 70% of children have delayed motor development and sexual maturation. Heredity in the first generation is burdened with autonomic dysfunction with a predominance of parasympathetic influences on the cardiovascular system: in 85% of families, one of the parents has arterial hypotension, bradycardia or first-degree AV block.

In non-paroxysmal supraventricular tachycardia of the recurrent type, the rhythm frequency during an attack of tachycardia is from 110 to 170 per minute. The average duration of attacks of non-paroxysmal supraventricular tachycardia of the recurrent type is about 30 sec, it can reach several minutes. In non-paroxysmal supraventricular tachycardia of a constant type, a regular (rigid) rhythm of a constant frequency (130-180 per minute) with a narrow ventricular complex is recorded. The rhythm of heart contractions in non-paroxysmal supraventricular tachycardia, as a rule, is rigid, however, in a "slower" tachycardia, the variation range of the RR intervals increases. A negative correlation was obtained between the duration of a tachycardia attack and the 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 cavity dilation. With the restoration of sinus rhythm, the sizes of the heart cavities return to the age norm within several weeks. Clinical and electrocardiographic criteria for the risk of developing arrhythmogenic cardiomyopathy for various forms of non-paroxysmal supraventricular tachycardia in children without organic heart disease are as follows:

• maladaptive response of the left ventricular myocardium to tachycardia according to echocardiography data;
• the average frequency of heterotopic rhythm is more than 140 per minute;
• low representation of sinus rhythm in the daily volume of cardiac cycles (less than 10% according to Holter monitoring data);
• disruption of synchronization of atrioventricular contractions, observed in AV dissociation and atrial fibrillation-flutter.

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

Instrumental methods

Electrocardiographic diagnostics allows differentiating between the types of supraventricular tachycardia in most cases. Typical (slow-fast) AV nodal reciprocating tachycardia is characterized by the onset of an attack with an extrasystole with an extended PR interval, during the attack a narrow QRS complex is recorded, the P wave is often not visualized or is retrograde (negative in leads II, III and aVF) with an RP interval of less than 100 ms. This arrhythmia is characterized by a paroxysmal form. Atypical tachycardia is characterized by slower retrograde conduction, it often has a non-paroxysmal course. This arrhythmia often leads to the development and subsequent progression of diastolic myocardial dysfunction. In addition, it is noted that in the presence of a long arrhythmic history, such patients also develop other types of supraventricular arrhythmias, such as atrial fibrillation, which significantly worsens the prognosis of the disease.

Orthodromic AV reciprocating tachycardia is characterized by a narrow QRS complex, slowing of the heart rate with the development of bundle branch block, the presence of ST segment depression and T wave inversion. The R-P interval is usually more than 100 ms. Sometimes alternans of the ventricular complex in amplitude is possible. Antidromic tachycardia is characterized by a wide QRS complex. In the manifest form of Wolff-Parkinson-White syndrome (the most common variant of antidromic tachycardia in children), antegrade conduction is carried out along the bundle of Kent. There is evidence of an increased frequency of the syndrome among patients with Ebstein's anomaly, tricuspid atresia, hypertrophic cardiomyopathy. On the ECG outside an attack of tachycardia, the criteria of the syndrome are as follows:

• shortening of the PR interval to less than 120 ms;
• presence of a delta wave before the QRS complex;
• widening of the QRS complex by more than 100 ms;
• secondary changes in the ST-T interval.

The polarity of the delta wave and the morphology of the QRS complex determine the presumed localization of the additional conduction pathway. The most unfavorable electrophysiological property of the additional pathway from the prognosis point of view is the ability to conduct high-frequency impulses 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 a ventricular complex of normal morphology. Functional AV block is often recorded. Ectopic tachycardias can be quite persistent, poorly amenable to drug treatment, and a rigid atrial rhythm often leads to the development of myocardial dysfunction. Multifocal (chaotic) atrial tachycardia is characterized by an irregular atrial rhythm of more than 100 beats per minute with variable polymorphic (at least three different variants) morphology of the P wave. An 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. Typical atrial flutter is caused by the circulation of the excitation wave through a certain anatomical zone - the isthmus between the orifice of the inferior vena cava and the fibrous ring of the tricuspid valve. This type of atrial flutter is rarely encountered in childhood. It is characterized by a regular P wave with a frequency of 250-480 per minute, the absence of an isoline between the P waves (sawtooth curve), variability of AV conduction (most often from 2:1 to 3:1). With atrial fibrillation, disorganized atrial activity is recorded with a frequency of up to 350 per minute (f waves), most often detected in leads V1 and V2. Ventricular contractions are irregular due to variability of AV conduction.

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