Sinus bradycardia in children
Introduction
Introduction to sinus bradycardia in children Sinus bradycardia refers to the frequency of sinus node excitatory is lower than the normal range, which is a common arrhythmia in children, but more asymptomatic, the exact incidence is unknown. The infant's heart rate is less than 100 beats per minute, 80 to 60 beats per minute from 1 to 6 years old, and sinus bradycardia is considered to be more than 60 beats per minute over 6 years old. Severe stagnation often occurs in borderline escape, sinus bradycardia can be seen in healthy children, athletes, also seen in cretinism, typhoid, obstructive jaundice, etc., in diseases with increased intracranial pressure, such as cerebral hemorrhage, brain Tumor and tuberculous meningitis and the application of foxglove, when the blood level, the heart rate can also be slow. Persistent bradycardia can be an early symptom of sick sinus syndrome and should be closely observed. basic knowledge Sickness ratio: 0.05% Susceptible people: children Mode of infection: non-infectious Complications: syncope cardiogenic shock
Cause
Causes of sinus bradycardia in children
(1) Causes of the disease
1. The vagus nerve tension is too high: more common in normal children, caused by excessive vagal tone, mainly in sleep, breath holding, when the stomach is significantly dilated, older children who are often engaged in exercise can also exhibit sinus bradycardia, pharynx Sinus bradycardia can also occur when sensitive children use a tongue depressor to examine the pharynx.
2. Pathological conditions: a few found in pathological conditions, heart diseases such as rheumatic myocarditis and viral myocarditis, increased cerebral hypoxia and intracranial pressure, typhoid, influenza and other infectious diseases, mucinous edema, hypothyroidism and hyperkalemia Symptoms can cause sinus bradycardia. The use of beta blockers, digitalis, quinidine, morphine and other drugs can cause sinus bradycardia.
3. After cardiac surgery: especially after atrial surgery, it is easy to cause sinus bradycardia.
(two) pathogenesis
1. Classification and mechanism of arrhythmia: Arrhythmia can be divided into three main categories according to their causes:
(1) Disorders of agitation: can be divided into two categories: sinus arrhythmia and ectopic rhythm, sinus arrhythmia including sinus tachycardia, sinus bradycardia, sinus arrhythmia, migratory rhythm and sinus Sexual quiescence, ectopic rhythm refers to ectopic pacemakers other than sinus node, such as decreased sinus node autonomy or blocked conduction, secondary pacing point excites, prevents cardiac arrest, called passive Position rhythm, one to two times said that escape, more than three times for escape rhythm, such as the increase in the self-discipline of the secondary pace point, the frequency of excitement exceeds the frequency of the sinus node, the first step in the sinus node Excited before, called active ectopic heart rhythm, one or two times is called premature beat, three times more than three times called tachycardia, the frequency is faster and regular called flutter, more quickly and without The regularity is called tremor, and the ectopic rhythm can be divided into atrial, borderline and ventricular according to the different pace points.
(2) Asymmetric conduction disorder: conduction disorder caused by physiological refractory period is called disturbance, most commonly occurs in the atrioventricular junction area. If multiple consecutive activations occur in the atrioventricular junction, interference is called interfering atrioventricular separation. Pathological conduction block can occur between the sinoatrial node and the atria, in the atrium, junction area and ventricle, respectively, called sinus conduction block, intraventricular block, atrioventricular block and bundle branch conduction. Blocking, when the activation through the atrioventricular bypass makes part of the ventricle first excited, called pre-excitation syndrome, which is abnormal in the conduction pathway.
2. Asymmetric conduction disorder: If the heart's excitement cannot reach the various parts at normal speed and order, it is conduction abnormality, which can be divided into physiological and pathological. The former refers to the fact that the excitation should not coincide with the conduction system during the conduction process. Period or relative refractory period, when the absolute refractory period is encountered, the excitement can not be transmitted. When the relative refractory period is encountered, the conduction is slow, also called the interference. The most common part of the disturbance is the atrioventricular junction area. More than one time at the junction of the atrioventricular junction, it is said that the interfering compartment is separated, the pathological conduction disorder is due to the organic changes of the conduction system, the conduction disorder caused by the pathological extension of refractory period, also known as pathological conduction resistance Stagnation, most of the slow arrhythmia is caused by this.
3. Agitated origin disorders with conduction disorders: belong to this type of parallel rhythm, repeated heart rhythm, ectopic heart rhythm combined with efferent block, parallel rhythm (parasystole) refers to the heart in addition to sinus pacing points, there are still Another frequently-occurring ectopic pacemaker; the ectopic pacemaker is surrounded by afferent blockade, making the sinus impulse a complete afferent block, which can excite at its own frequency without Under the influence of normal sinus agitation, the two pacemakers are excited in parallel. If there is no blockage at the ectopic pacemaker, as long as the surrounding myocardium is not in the refractory period, it can be circulated and formed once. Atopic premature contraction can also form a parallel heart rhythm tachycardia.
Prevention
Prevention of sinus bradycardia in children
Prevention of various heart diseases such as rheumatic myocarditis and viral myocarditis; active treatment of hypothyroidism, uremia, rheumatic fever, Kawasaki disease, nervous system factors, hypothermia, anesthesia and drug poisoning, etc.; prevention of high blood Sinus bradycardia caused by potassium and various drugs.
Complication
Pediatric sinus bradycardia complications Complications, syncope, cardiogenic shock
Often concurrent with borderline escape or sick sinus syndrome, significant heart rate can be reduced when syncope, convulsions, often accompanied by arrhythmia, cardiogenic shock.
Symptom
Symptoms of sinus bradycardia in children Common symptoms Chest tightness Bradycardia, dizziness, convulsions, syncope
Normal children with sinus bradycardia generally have no clinical manifestations. Most of them have a physical examination or other reasons for electrocardiogram or 24h electrocardiogram. It is found that when the sinus bradycardia is caused by pathological causes and the heart rate is obviously slow, mental disorder may occur. Burnout, older children can complain of dizziness, chest tightness, significant heart rate can slow down when there may be syncope, and even convulsions, arrhythmia is slow, often accompanied by arrhythmia, heart sounds can be normal.
Examine
Pediatric sinus bradycardia check
General routine examinations are normal, such as after a certain disease, laboratory tests vary with the original disease. Routine chest X-ray, echocardiography, and other clinical needs. ECG features:
Conventional electrocardiogram (awake and rest)
(1) Sinus P wave, I and II are vertical waves, and the aVR lead is inverted.
(2) Slow heart rate: <1 year old <110 times/min; 1 to 3 years old <90 times/min; 3 to 5 years old <80 times/min; 5 to 10 years old <70 times/min; 10 years old or older <60 Times / min.
Characteristics of dynamic electrocardiogram (at sleep): <1 year <80 times/min; 2-6 years <60 times/min; 7-11 years <45 times/min; 12 years old <40 times/min; athletes <30 Times / min.
Diagnosis
Diagnosis and diagnosis of sinus bradycardia in children
diagnosis:
According to the clinical manifestations and characteristics of electrocardiogram or dynamic electrocardiogram, the diagnosis of sinus bradycardia is not difficult.
Differential diagnosis:
1. Sick sinus syndrome: exercise test or sinus node function stimulation test, heart rate increase is less than 20% to 30% of the original heart rate, considering sick sinus syndrome, and sinus bradycardia can be significantly increased However, persistent sinus bradycardia may be an early manifestation of sick sinus syndrome.
2. Sinus conduction block: After sinus conduction block in the injection of atropine or exercise, the heart rate can be multiplied, while sinus bradycardia gradually accelerates.
3.2:1 atrioventricular block: sometimes blocked P wave overlap T wave, pay attention to the T wave shape with or without hidden P wave, can help diagnose.
