Pediatric Sick Sinus Syndrome

Introduction to pediatric sick sinus syndrome Sick sinus syndrome (SSS) is an organic lesion of the sinus node and atrial conduction system due to various reasons, which causes the pacing frequency to decrease or the efferent block to occur. The sinus node loses the leading role of cardiac pacing, thus producing various arrhythmias, and has clinical symptoms of insufficient blood supply to the heart, brain and kidney, called sick sinus syndrome. Sick sinus syndrome, also known as sinus node dysfunction (sinusnodedysfunction), referred to as sick sinus syndrome or sick sinus, when the bradycardia and cerebral hypoxia syncope or convulsions, also known as A-S syndrome (Adams-Stokessydrome ), bradycardia and ectopic rapid heart rhythm such as supraventricular tachycardia, atrial flutter, etc., can alternately appear, this is called fast and slow syndrome. Sick sinus is rare in children compared with adults, and the incidence rate is not detailed. basic knowledge The proportion of illness: 0.002% Susceptible people: children Mode of infection: non-infectious Complications: angina pectoris, syncope, a syndrome, shock, heart failure, sudden death

Etiology of pediatric sick sinus syndrome

(1) Causes of the disease

Myocarditis, pericarditis, cardiomyopathy caused by other systemic diseases, intracardiac surgical trauma, etc. can cause this disease, often after cardiac surgery, such as Mustard orthodontic repair of a large vessel dislocation and more than atrial septal defect repair, etc. Within a few weeks after surgery, it can also last for more than 10 years. During intracardiac surgery, the superior vena cava is intubated, and the sinus node is damaged when cutting the happy room or surgical suture, causing bleeding, necrosis and sinus node embolization. Caused by sinoatrial node steatosis and extensive fibrosis, congenital heart disease may be associated with sinus node malformation such as single atrium, in addition, hemodynamic changes in congenital heart disease, so that the sinus node is compressed, pulled or Hypoxemia can also lead to sinus node dysfunction. After surgical rectification, the sinus node function can be restored. Some cases have unknown etiology, and the heart test is normal. Only the specific electrocardiogram changes of this disease are caused. Therefore, some people think that The disease is a special type of cardiomyopathy characterized by atrial and cardiac conduction system lesions.

(two) pathogenesis

The sinus node artery is the only artery that supplies the sinus node. When the sinus node is blocked or the sinus node is damaged, it can cause sinus node dysfunction, sinus rest or sinus block, and then concurrent Supraventricular tachycardia, atrial flutter, atrial fibrillation, ventricular tachycardia or ventricular fibrillation, etc., on the contrary, rapid depression of rapid heart rhythm can further inhibit sinus node function and sinus rest or Combined with bradycardia such as sinus block, alternating tachycardia-slow or bradycardia-tachycardia arrhythmia syndrome.

Prevention of sinus syndrome in children

Actively prevent congenital heart disease; actively prevent and cure various myocarditis, cardiomyopathy and myocardial damage, actively improve the surgical method, avoid damage to the sinus node and its surrounding tissues, and strengthen postoperative treatment to prevent the occurrence of sick sinus.

Complications of sinus sinus syndrome in children Complications, angina, syncope, A-s syndrome, heart failure, sudden death

Can be complicated by angina, syncope, convulsions, A-S syndrome, decreased exercise tolerance, shock, heart failure, and even sudden death.

Symptoms of sinus syndrome in children Common symptoms Fatigue palpitations, tachycardia, sputum, dizziness, intraventricular conduction block, chest tightness, conduction block, atrioventricular separation, heart failure

The onset of the disease is slow, the course of disease is prolonged, the short period of several months to 1, 2 years, the elderly for more than 10 years, usually with persistent bradycardia as the main symptom, due to bradycardia or sinus rest, can cause heart , brain, kidney, gastrointestinal and other organs of the symptoms of insufficient blood supply, light fatigue, dizziness, chest tightness, palpitations, anorexia, memory loss, severe cases can occur A-S syndrome, or even sudden death, due to children's borderline escape The frequency of heart rhythm is faster, so the symptoms are milder and difficult to be detected. In a few cases, rapid heart ectopic rhythm affects heart function, but shock, congestive heart failure or embolism occurs. ECG changes are mainly slow heart rate, common sinus Bradycardia, sinus rest, length II, or type II sinus block, borderline escape on the basis of slow heart rhythm, borderline rhythm, atrioventricular septum, due to atrioventricular junction Delayed escape of the affected, up to 1.2s, such slow heart rhythm can be converted into rapid ectopic heart rhythm in the short term, such as supraventricular tachycardia, atrial flutter, atrial fibrillation, etc., called fast-slow syndrome Atrial period Contraction is more common than ventricular premature contraction. In a few cases, atrioventricular block can be blocked at the same time. P wave tends to be low or double-peak, and time is widened, suggesting that there is a block in the room. The diagnosis is combined with the diagnosis. In addition to clinical manifestations and ECG changes, sinus node function tests should be performed, sinus node sympathetic, parasympathetic innervation, excitation vagus nerve and application of -blockers can inhibit sinus node function, causing sinus bradycardia and Sinus block, such patients with sinoatrial node function stimulation test, such as atropine test, to distinguish between pathological or vagal hyperfunction.

Examination of sinus sinus syndrome in children

First, laboratory inspection

Myocardial zymogram, erythrocyte sedimentation rate, anti-"O", blood electrolysis value, pH value and immune function should be routinely examined.

Second, auxiliary inspection

Conventional electrocardiogram, chest X-ray, echocardiography.

1. Transsphenoidal or direct atrial pacing to detect sinus node function: This method is a reliable method for the diagnosis of sick sinus syndrome, especially combined with drugs to block the influence of the autonomic nervous system, and can improve sensitivity. The bipolar pacing catheter was inserted through the esophagus, the electrode was placed behind the left atrium, and then the artificial cardiac pacemaker was connected to perform rapid pacing. The frequency was increased from 90 times, 100 times, 120 times per minute to 150 times per minute. Each pacing lasts for 1 minute, then terminates the pacing, and traces the electrocardiogram to see how long the sinus node can wake up and re-jump, from the time of stopping the stimulation pacing to restoring the sinus P wave for the recovery of sinoatrial node time. The intrinsic heart rate of patients with sick sinus syndrome was below 80 beats/min (measured after atropine 2mg plus propranolol 5mg intravenous injection), sinus node recovery time >1500m.s, sinus conduction time >180m.s.

2, body surface electrocardiogram (including Holter Holter):

(1) persistent sinus bradycardia, no other explanation. The heart rate is divided into <90 times/min under 1 year old, <70 times/min from 1 to 6 years old, and <50 times/min over 7 years old.

(2) sinus bradycardia with sinus block, sinus rest or escape.

(3) sinus bradycardia and ectopic tachycardia alternately appear, also known as fast and slow syndrome.

(4) Long-lasting slow escape rhythm.

(5) P wave is low or double peak, and the time is widened, suggesting that there is an intraventricular conduction block.

3, isoproterenol test: 0,25mg isoproterenol added to 10% glucose solution 100ml, intravenous infusion at 0,05 ~ 2g / (kg · min), the results of recording and positive judgment standard with atropine . This test is prone to cause ventricular ectopic rhythm, less safe than atropine, but less false positive or false negative.

4, atropine test: atropine 0, 02mg / kg, dissolved in saline 2ml rapid intravenous injection, before injection and immediately after the injection, 1,3,5,7,10,15,20min each trace an ECG to measure heart rate And analyze other ECG changes. One of the following conditions after the injection is positive:

(1) The heart rate increased not to reach 90 to 100 times/min.

(2) sinus block or atrioventricular block.

(3) Sudden or ventricular rapid heart rate. In the sick sinus syndrome, the atropine test can be false negative, and the atropine dosage is 0, 01 mg/kg, the false negative is higher. It should be judged by combining the clinical manifestations with the results of other tests.

5, electrocardiographic examination: the application of right atrial pacing or transesophageal atrial pacing to measure sinus node function, reliable method, sinus node function test: sinus node recovery time (SNRT) 1200ms [normal value: (913 ±139,7)ms], corrected sinus node function recovery time (CSNRT) 350ms [normal value: (247, 7±51, 3) ms], sinus conduction time (SACT) 140ms [normal value: ( 102, 5 ± 18, 6) ms], suggesting dysfunction of the sinus node.

6, exercise test: exercise test is relatively simple, safe and safe. The submaximal exercise was used for the treadmill exercise test for 2 min, the speed was 2 /h, and an electrocardiogram was recorded before and after exercise. The positive test results were the same as the atropine test.

7, 24h dynamic electrocardiogram: observe the degree of slow ventricular rate and whether or not complicated ventricular premature contraction, ventricular tachycardia and other serious arrhythmias.

8, exercise ECG: observe the child's exercise endurance, the rate of ventricular increase after exercise and whether to induce ventricular arrhythmia. If the ventricular rate increases by more than 10 times/min after exercise, it indicates that the blockage is above the His bundle.

9. His's beam diagram: Determine the blockage, at the junction of the atrioventricular, His bundle or His bundle.

10, echocardiography: congenital complete atrioventricular block for fetal echocardiography, observe the relationship between atrioventricular contraction, can be diagnosed before birth.

11, determination of sinus node function recovery time: the use of electrode catheter in the right atrial pacing or esophageal atrial pacing method to determine the recovery time of sinus node, correction of sinus node recovery time and sinus conduction time. The normal values of transesophageal atrial pacing were (913±139, 7) ms, (247, 7±51, 3) ms and (102, 5±18, 6) ms. If the normal upper limit was exceeded, the sinus was The function of the node is incomplete. Although this method is more reliable, it requires certain equipment, so it is not convenient for promotion.

Using Holter ECG monitoring for 12 to 24 hours, a series of ECG changes can be observed, which can assist diagnosis. It is a reliable non-invasive examination method, which can avoid sinus node function examination.

Diagnosis and diagnosis of sinus syndrome in children

diagnosis

According to one of the first three items of ECG characteristics, the sick sinus syndrome can be considered in combination with clinical manifestations, but the diagnosis of drugs and metabolic disorders is excluded, and the vagus nerve function is excluded by atropine test or exercise test. Conditional patients should determine the recovery time of sinus node function.

Differential diagnosis

Sick sinus syndrome needs to be distinguished from sinus bradycardia caused by hyperkinesia. The latter is generally normal, and the atropine test and exercise test are negative.

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