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Disruption of automatism



Nomotopic rhythm disturbances. Sinus arrhythmia is manifested in recurrent increases and decreases in heart rate. Patients do not complain. Sinus arrhythmia is often associated with the phases of respiration, can occur in healthy children. Respiratory arrhythmia occurs when the inspiratory heart rate increases and the exhalation heart rate decreases. It is caused on the inhale by a reflex decrease in the tone of the vagus nerve, on the exhale by an increase in the tone of the vagus. On ECG, a change in heart rhythms (R-R or P-P intervals of various durations due to an increase in diastolic T-P intervals).

Sinus bradycardia - a decrease in the number of heartbeats. It is due to the increased influence on the sinus node of the parasympathetic nervous system or a decrease in the influence of the sympathetic nervous system. It occurs in healthy children-athletes, with vascular dystonia of vagotonic type, with rheumatism, hypothyroidism, traumatic brain injury, brain tumors, some infectious diseases. Patients do not complain. On the ECG, the atrial and ventricular complexes are not changed, the interal RR (cardiac cycle), T – P (heart diastole) are extended, the duration of the interval P — Q is slightly increased.

Sinus tachycardia - an increase in the number of heartbeats. Associated with the impact on the sinus node of biologically active substances that increase its excitability, or an increase in the tone of the sympathetic nervous system, or a decrease in the tone of the vagal nerve. There is sinus tachycardia with physical and emotional stress, fever, organic heart disease, various infections and intoxications, thyrotoxicosis. On the ECG, the atrial and ventricular complexes are not changed, the inteval R — R (cardiac cycle), T — P (diastole of the heart) are shortened.

Heterotopic rhythm disturbances. Nodal rhythm - an increase in the automatic function of the atrioventricular node and a decrease in the automatic ability of the sinus node due to functional or organic changes. Complaints do not show, sometimes complaints of a pulsation in the neck, which is noted while reducing the atria and ventricles. When auscultation of the heart is determined by the gain of 1 tone. On an ECG - the negative tooth P precedes the QRS complex, the interval R - R is shortened.

A periodic change in rhythm from the sinus to the atrioventricular node is observed. In this case, the heart is excited under the influence of impulses emanating alternately from the sinus node, then from the atrial conductive system, then from the atrioventricular junction, and the pacemaker migrates again in the same sequence. No complaints, no objective changes. The clinical picture is reduced to the underlying disease (rheumatism, intoxication). On the ECG, the shape, amplitude, position of the P wave, as well as the duration of the interval P — Q, which, when moving to the atrioventricular node, becomes shorter, changes.

Extrasystole - premature contraction of the whole heart or its individual part, arising under the influence of an additional focus of excitation coming from the sinus node. Causes: inflammatory, dystrophic, degenerative, toxic, mechanical damage and neurogenic disorders. Depending on the place of origin, ventricular, atrial, atrioventricular are distinguished. Extrasystoles can be single, multiple, can occur after each contraction in a certain sequence (bigemia) or after two contractions (trihemia). Extrasystoles that occur in various ectopic centers are called polytopic. Complaints often do not show, sometimes there are discomfort in the heart (fading, stopping, a strong push). With auscultation of the heart, there are additional pulse beats, additional heart sounds. In atrial arrhythmia, excitement from an ectopic focus begins before monotopic arousal, and after a premature contraction of the heart, a long incomplete compensatory pause occurs. On an ECG, a deformed P wave is premature or overlaps on the previous P wave, shortening the R interval — R, the QRS complex is not changed, the T — P interval is moderately increased.

With atrioventricular extrasystoles, the impulse comes from the node of Aschoff-Tavara, extends retrograde to the atria, from the bottom up, and the excitation of the ventricles usually goes. On an ECG - a negative tooth P in a different location in relation to the QRS complex, or in front of the complex, or merges with it, or goes after it, the shape of the QRS complex is not changed, the interval T - P is equal to two normal heartbeats (full compensatory pause).
With ventricular extrasystoles, the excitation sequence of the heart changes, the impulse arising in the ventricles does not extend retrograde, and the atria are not excited. The excitation of the ventricles is alternately and non-simultaneous, as is normal, depending on the location of the ectopic focus.

On ECG, ventricular extrasystoles appear:

1) premature occurrence of a QRS complex without a preceding P wave;

2) the QRS complex with a high voltage, is wide, split, jagged, a passing tooth of T without interval S - T;

3) discoordinate direction of the T wave relative to the maximum tooth of the QRS complex extrasystoses;

4) the lengthening of the compensatory pause after an extrasystole, the distance between two R — R intervals, including an extrasystole, is two normal cycles. There are right and left ventricular extrasystoles:

a right ventricular extrasystole in 1 assignment the largest tooth of the R complex of a QRS, extrasystoles are directed up, and in 3 assignments the S tooth, directed downwards is greatest.

In the left ventricular type in 1 lead, the largest tooth S of the complex QRS extrasystoles is directed downward; in 3 leads, the R tooth is directed upward. The origin of a functional extrasystole due to a violation of extracardiac, often autonomic, regulation.

The main signs of functional extrasystole (most often found in prepubertal and pubertal age):

1) labile during the day, changes when changing the position of the body, during exercise;

2) children show signs of vegetative dystonia, foci of chronic infection, endocrine disorders;

3) when using special methods of research, no violations of myocardial contractility are detected; clinorotostatic test, sample with metered exercise, pharmacological tests with ECG recording testify in favor of functional extrasystole. The origin of organic extrasystoles arises from the defeat of the myocardium or the cardiac conduction system. The main features of organic extrasystoles:

1) permanent;

2) the general condition is usually disturbed and there are signs of organic heart disease (rheumatism, non-rheumatic carditis, congenital heart defects).

Paroxysmal tachycardia is an attack of a sharp increase in heartbeat, 2-3 times higher than normalization of rhythm, which occurs when there is an ectopic center capable of producing high frequency impulses. Complaints in older children of discomfort in the heart, a feeling of tension in the neck, dizziness, fainting, pain in the underbelly, abdomen. In young children, paroxysmal tachycardia is accompanied by convulsive and dyspeptic symptoms. An objective examination of dyspnea, cyanosis, pulsation of the veins, congestion in the lungs, liver enlargement, pulse can not be counted, small filling, lowering blood pressure.

The atrial, atrioventricular, ventricular forms of paroxysmal tachycardia are distinguished. An ECG in atrial paroxysmal tachycardia reveals a long series of atrial extrasystoles with a sharp shortening of the interval T – P, the layering of the P wave on the T wave with its deformation, QRS complex is not changed or moderately deformed, the atrioventricular paroxysmal tachycardia is characterized by a repeated pattern and is applied by a simple pattern, and is applied and has a simple pattern, and a cross-sectional pattern is applied. , or their displacement on the QRS complex, or by merging with the T wave. The ventricular form of paroxysmal tachycardia on the ECG is a deformed, expanded complex QRS. Atrial teeth P appear regularly and layered on the ventricular complex of extrasystoles.

Atrial fibrillation is a violation of the correct activity of the atria due to the appearance in the atria of one or more foci of excitation. Complaints about the deterioration of health, a sense of fear, anxiety. During auscultation, different sonic tones, random alternation of short and long pauses, the number of ventricular contractions depends on the form of atrial fibrillation, there is a shortage of pulse (during auscultation the number of heart contractions is greater than the pulse waves). On the ECG, the P wave is absent and is slowed down by waves of various sizes and shapes. The QRS complex is not changed, the interval S — T is below the isoelectric line, the T wave and the isoelectric line are deformed by twinkling waves.

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Disruption of automatism

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