Neonatal arrhythmia

Introduction to neonatal arrhythmia Neonatal arrhythmia refers to an abnormal heart rhythm that is different from normal heart beat rhythm due to myocardial self-discipline, excitability, and conduction changes, including frequency, rhythm, heart beat, or abnormality of cardiac electrical activity. Neonatal arrhythmias are mostly functional and temporary, but there are also a few severe arrhythmias that can cause sudden death in neonates. Therefore, neonatal arrhythmia should not be taken lightly. It should be closely observed, active treatment, and clinically common arrhythmia. Primary ventricular tachycardia, sinus bradycardia, atrial and premature contractions, ventricular premature contractions, atrioventricular block. basic knowledge The proportion of illness: 0.03% Susceptible people: children Mode of infection: non-infectious Complications: heart failure, shock, syncope, cerebral embolism, sudden death

Neonatal arrhythmia

Disease factors (20%):

Various organic heart diseases such as congenital heart disease, viral myocarditis, cardiomyopathy, etc. Various neonatal infectious diseases such as neonatal pneumonia, sepsis, upper respiratory tract infection, intestinal infection, etc.

Physical factors (15%):

Neonatal asphyxia and hypoxia are common causes of arrhythmia, other perinatal factors (ie abnormalities of mother and fetus before and after fetal delivery) such as prenatal and postpartum medication, fetal umbilical cord around the neck, head basin is not called, intrauterine Distress, etc. can cause arrhythmia.

Endocrine factors (18%):

Water, electrolyte balance disorders such as hypokalemia, hyperkalemia, hypocalcemia, acidosis, and certain drugs such as digitalis.

Other factors (15%):

Neonatal cardiac catheterization and cardiac surgery. Arrhythmia can occur in healthy newborns, which may be related to the immature development of the conduction system.

Neonatal arrhythmia classification (10%):

(1) sinus arrhythmia: sinus tachycardia, sinus bradycardia, sinus arrhythmia, sinus arrest, sick sinus syndrome (sinus node dysfunction).

(2) ectopic beats and ectopic rhythm: premature beats (atrial, uterus, ventricular), supraventricular tachycardia, atrial fibrillation, atrial flutter, ventricular tachycardia, ventricular flutter and Trembling.

(3) conduction abnormalities: sinus conduction block, atrioventricular block, bundle branch block, pre-excitation syndrome.

Pathogenesis

1. Excited origin is abnormal

Many parts of the heart have self-regulatory cells, which are self-disciplined. The electrophysiological basis is the 4-phase diastolic autodepolarization activity. The normal sinus node is the most self-disciplined, and the frequency of impulse is the fastest. The following is the atrial special. Conductive tissue, junction zone, His bundle, bundle branch and Purkinje fiber, due to the fastest depolarization rate of sinus node diastole, the impulse is reached earlier and reaches the threshold potential, and is transmitted to the heart, other parts The pacing cells have been excited by the impulse transmitted by the sinus node before the membrane potential rises to the threshold, so their autonomy is inhibited. When the myocardial lesions, such as injury, ischemia, hypoxia, etc., the sinus node is exposed. Inhibition, the underlying self-regulatory cells are forced to release impulses, which is a protective mechanism that can produce escape or escape rhythm. If the autonomicity of the diseased cardiomyocytes is abnormally increased, the frequency of impulses is increased, exceeding the sinus node. , the active ectopic rhythm occurs, one or two consecutive times are pre-systolic, three or more times are tachycardia, ectopic beats occur continuously and the frequency is faster but the ruler is fluttering, Irregularities are trembles.

2. Excitatory conduction disorder

(1) Conduction block: If the heart's excitement cannot reach each part 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 is in the conduction process. During the period of response or relative refractory period, when the absolute refractory period is encountered, the excitement cannot be transmitted. When the relative refractory period is encountered, the conduction is slowed down, also called the disturbance. The most common part of the disturbance is the atrioventricular junction area. More than 3 times of interference 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 Blocking, most of the slow arrhythmia is caused by this.

(2) Reentry: Reentry is a common mechanism of supraventricular tachyarrhythmia, especially in pre-excitation syndrome. The condition for completing reentry is: one-way block; conduction slowing; reentry anterior myocardial recovery faster The stress is so that the excitation is blocked in the proximal end of the one-way block, and then transmitted through another path, and then passed through the one-way block, and the original excitatory part has been detached from the refractory period. You can re-enter the loop and repeat the loop to produce a reentry rhythm (Figure 1).

3. Agitated origin disorders with conduction disorders

Belonging to this category are parallel heart rhythms, repeated heart rhythms, and ectopic heart rhythms combined with blockades.

(1) Parallel heart rhythm: Parasystole means that in addition to the sinus pacemaker point in the heart, there is another ectopic pacemaker that is often active; there is an afferent resistance around the ectopic pacemaker. The stagnation protection makes the sinus impulse a complete afferent block, which can be stimulated at its own frequency without being affected by normal sinus agonism. For this reason, the two pacemakers are excited in parallel, in the ectopic pacing. If there is no blockage of the point, as long as the surrounding myocardium is not in the refractory period, it can be circulated, and an ectopic premature contraction can be formed. Parallel rhythm tachycardia can also be formed, and the congenital premature contraction The characteristics are that the pairing time is not equal, often there is a fusion wave, and the long ectopic beat interval is a simple multiple of the short ectopic beat interval.

(2) ventricular late potential: ventricular late potential (delayed fractionated electrical activity) in a small myocardial part of the ventricle during the diastolic phase; these fragmentation electrical activities generally occur in In the ST segment, it is called the ventricular late potential, which is characterized by low amplitude, high frequency pleomorphic spikes, sometimes equipotential lines between the sharp waves, and the appearance of ventricular late potentials indicating isolation from each other in the small myocardial There are unsynchronized electrical activities in each muscle bundle. Due to the unsynchronized electrical activity, it may provide conditions for the occurrence of reentry agonism, or it may be due to too little connection between the myocardial fibers, causing slow conduction. Reentry excitability provides an important factor, so it can not only produce premature contractions, but often malignant ventricular arrhythmias.

Neonatal arrhythmia prevention

Prevention of heart disease; prevention of electrolyte imbalance and acid-base imbalance, active treatment of primary disease, such as various gastrointestinal disorders; hypothyroidism, uremia, nervous system factors, hypothermia, anesthesia and drug poisoning caused by arrhythmia, The primary disease should be actively treated.

Neonatal arrhythmia complications Complications, heart failure, shock, syncope, cerebral embolism, sudden death

Heart failure, shock, syncope and cerebral embolism, sudden death, etc.

Neonatal arrhythmia symptoms common symptoms fatigue, dizziness, palpitations, palpitations, sleepiness, refusal, irritability, pale, heart failure, heart sound, low blunt

1. The onset characteristics of neonatal arrhythmia

(1) Functional and temporary arrhythmias are more common.

(2) The incidence of disturbances in the conduction system is high.

(3) often disappears on its own, and the prognosis is better than that of older children and adults.

(4) The prognosis of arrhythmia depends on the primary disease that causes arrhythmia.

2. General clinical manifestations

Arrhythmia causes hemodynamic changes due to excessive heart rate, too slow and inconsistent atrioventricular contraction. The degree of hemodynamic effects depends on whether the heart is normal and how the heart compensates function. Common symptoms Heart palpitations, fatigue, dizziness, severe coma, shock, heart failure, babies can suddenly appear pale, refusal to eat, vomiting, lethargy, etc., children with paroxysmal tachycardia often have a history of recurrent attacks.

Some arrhythmia changes in frequency, rhythm, etc., heart sound changes, such as the first degree of atrioventricular block, the first heart sound often weakens, the first heart sounds strengthen when paroxysmal supraventricular tachycardia, Heart sounds vary in atrial fibrillation. The first heart sound is sometimes called "cannon sound" when complete atrioventricular block.

3. Sinus tachycardia

(1) common causes of sinus tachycardia: neonatal sinus tachycardia is mostly sympathetic nerve excitability, the result of enhanced adrenaline activity in the body, common in:

1 Physiological factors: healthy newborns crying, activity increases, after feeding.

2 pathological factors:

A. Systemic diseases: neonatal fever, anemia, various infections, shock, heart failure and certain drugs such as atropine, adrenaline and other applications.

B. Organic heart disease: Certain organic heart diseases such as viral myocarditis, congenital heart disease, etc.

(2) frequency of sinus tachycardia: neonatal sinus node is distributed with tachycardia, the frequency exceeds the upper limit of the normal range, called sinus tachycardia. It is generally considered that the upper limit of sinus heart rate in full-term children is 179-190 beats/min. The upper limit of premature infants is 195 beats/min. When neonatal sinus tachycardia, the heart rate can reach 200-220 beats/min. Some authors reported that the fastest heart rate of neonatal sinus tachycardia can reach 260 beats/min.

4. Sinus bradycardia

Neonatal sinus node release is too slow, the frequency is lower than the lower limit of the normal range. It is called sinus bradycardia. It is generally believed that the lower limit of sinus rhythm in full-term children is 90 beats/min. It is reported that the heart rate can be slow when the full-term child falls asleep. 70 times / min, premature infants are slightly lower than full-term children, ECG has the characteristics of sinus rhythm.

Neonatal sinus bradycardia is mostly caused by increased parasympathetic excitability, and can also be caused by abnormal sinus node, which is seen in the following cases:

(1) Some physiological activities of normal newborns such as snoring, swallowing, yawning, urination, defecation, etc. can cause sinus bradycardia, and small premature infants may have obvious sinus bradycardia even when nasal feeding, stimulating parasympathetic nerves. Such as pre-stress, eyeball, stimulating the nasopharynx, carotid sinus and clamping the umbilical cord can cause sinus bradycardia, heart rate can be as slow as 80 times / min.

(2) Certain organic heart diseases such as viral myocarditis, congenital heart disease and other diseases affect the sinus node, and open heart surgery can damage sinus node, which can cause sinus bradycardia.

(3) When or after neonatal apnea, fetal distress, neonatal asphyxia, hypothermia, severe hyperbilirubinemia, hypothyroidism, elevated intracranial pressure (see intracranial hemorrhage, intracranial infection) Etc.), electrolyte disorders such as hyperkalemia, and certain drugs such as digitalis, lidocaine, quinidine, and mothers with beta-blockers, can cause sinus bradycardia.

5. Sinus node dysfunction

In 1985, Rein et al reported neonatal and infant sinus node dysfunction (SND), which refers to sinus node due to some pathological reasons or due to autonomic dysfunction can not normally send impulse or impulsive transmission blocked A series of clinical manifestations such as sinus bradycardia, sinus arrest, sinus block, bradycardia - overspeed syndrome, fainting, apnea, cardiac arrest and so on.

6. Symptomatic SND

Due to neonatal, especially premature infants, temporary development of sinus node in low-weight children is imperfect, some diseases and neonatal asphyxia, hypoxia, apnea, hyaline membrane disease, pneumonia, blood viscosity, easy to cause ischemia , a series of symptoms of hypoxia.

7. Non-symptomatic SND

It refers to the congenital dysplasia of the sinus node (such as the sinus node congenital absence), structural heart disease such as congenital heart malformation caused by abnormal sinus node structure, viral myocarditis and other myocardial inflammation caused by sinoatrial node degeneration, necrosis And a series of clinical manifestations caused by cardiac surgery injury sinus node.

In addition to the primary disease, the main symptoms are cyanosis, shortness of breath, heart rate change, heart rate is slow, there may be leakage, but also slow-fast heart rate alternation, severe cases of convulsions, coma, cardiac arrest, etc. .

8. Paroxysmal supraventricular tachycardia

Paroxysmal supraventricular tachycardia is a common arrhythmia in neonates and one of the clinical emergencies in the neonatal period.

Paroxysmal supraventricular tachycardia can occur in intrauterine and postnatal, paroxysmal supraventricular tachycardia, because of its excessive heart rate is often misdiagnosed as intrauterine distress, the array after birth Sudden onset of supraventricular tachycardia, sudden onset of illness, children with shortness of breath, perioral cyanosis, pale, irritability, refusal to milk, liver, etc., heart rate is fast and uniform, generally 230 ~ 320 times / min, Heart failure is prone to attack for more than 24 hours.

9. More common in neonates without structural heart disease, due to immature heart conduction system development, 50% to 58% with pre-excitation syndrome.

10. Organic heart disease such as viral myocarditis, congenital heart disease with atrial hypertrophy such as tricuspid atresia, dislocation deformity, atrial septal defect and so on.

11. Non-cardiac diseases such as neonatal asphyxia, infectious diseases such as pneumonia, diarrhea, electrolyte imbalance, etc.

12. Drug poisoning (such as digitalis), cardiac catheterization and cardiac surgery.

13. Paroxysmal ventricular tachycardia

Paroxysmal ventricular tachycardia is rare in newborns. It is a serious arrhythmia that requires urgent treatment. The condition is more serious. It has clinical manifestations of primary disease. Because of ventricular tachycardia, cardiac output is reduced. The performance of stimuli and heart failure, children with pale, heart sounds low blunt, blood pressure decreased, peripheral circulation is poor, can also have cardiogenic cerebral ischemia, convulsions, coma, etc., ventricular rate is generally below 200 beats / min .

Paroxysmal ventricular tachycardia is more common in severe organic heart disease such as viral myocarditis, congenital heart disease, cardiomyopathy, etc. It can also be found in the end stage of some serious systemic diseases, or certain drugs such as foreign countries. Poisoning and other poisoning, severe electrolyte imbalance and cardiac catheterization, cardiac surgery.

14. Premature beat

Premature beats are referred to as pre-systolic contraction, which is the most common type of neonatal arrhythmia. The incidence rate is 2%-23% in healthy full-term neonates and 21% in preterm infants. 31%, in the various arrhythmias of neonates, pre-contraction accounted for the largest proportion, in the pre-systolic contraction, the most common atrial, followed by borderline and ventricular.

Prenatal neonatal contraction can occur in healthy children. The cause of premature contraction in healthy newborns is mainly due to the immature development of the heart's conduction system. This pre-contraction disappears within 1 month, and pre-contraction can also occur. Children with structural heart disease such as viral myocarditis, congenital heart disease and various non-cardiac diseases such as asphyxia, upper respiratory tract infection, pneumonia, sepsis, neonatal electrolyte imbalance, drugs such as digitalis poisoning, maternity Premedication can cause premature contraction. Premature contraction can also be caused by cardiac catheterization and cardiac surgery. Some premature contractions can occur in the uterus. The causes are intrauterine distress and intrauterine infection.

15. Atrioventricular block

Atrioventricular block is a common arrhythmia in the neonatal period. According to the severity of the block, the degree of second-degree, third-degree atrioventricular block can be divided into congenital and acquired according to the cause. Once atrioventricular block and second degree atrioventricular block and leakage, the clinical is mostly asymptomatic, auscultation may have the first heart sound of the apex of the heart is low blunt, can be heard of leakage, second degree atrioventricular block and leakage Multiple and third degree atrioventricular block ventricular rate is slow, resulting in decreased cardiac output, children may have difficulty breathing, shortness of breath, pale, cold limbs, blood pressure, weak pulse, due to cardiogenic cerebral ischemia Convulsions, coma, congenital third degree atrioventricular block can occur in the uterus, usually in the late pregnancy or delivery, fetal bradycardia, often misdiagnosed as intrauterine distress and emergency cesarean section, heart rate after birth 56 to 80 beats / min can be asymptomatic, such as heart rate slow to 30 ~ 45 times / min symptoms, third-degree atrioventricular block in the heart auscultation, the first heart sounds vary, because the complete room The uncoordinated contraction of the chamber separation chamber results in different heart output per stroke. Diagnosis of the left sternal border can be heard in the second to third grade systolic jet murmur and the third apex of diastolic phase in the apical region, caused by high cardiac stroke output, congenital third degree atrioventricular block is about 40% Congenital heart disease, when you can hear the noise caused by congenital heart malformation.

Neonatal atrioventricular block can be divided into congenital and acquired, congenital majority of third-degree atrioventricular block (complete atrioventricular block), due to abnormal embryonic development and pregnant women with autoimmune Disease, immune antibody damage caused by fetal conduction system, acquired by organic heart disease such as viral myocarditis, cardiomyopathy, congenital heart disease and infection, hypoxia, electrolyte imbalance, drugs such as digitalis poisoning First- and second-degree type I atrioventricular block can also be caused by increased vagal tone, also seen in normal newborns.

Neonatal arrhythmia examination

Depending on the cause of arrhythmia, electrolytes and acid-base balance should be routinely examined; thyroid function and renal function should be examined; erythrocyte sedimentation rate, anti-O and immune function should be examined.

Electrocardiogram

It is the main method for diagnosing arrhythmia. Firstly, find a lead with obvious P wave in each lead of ECG, measure PP interval, determine atrial rate, observe the law of P wave, whether the shape of P wave is normal, and whether PP interval is normal. Consistently, identify abnormalities, premature occurrence, slowness, sinus block or arrest, secondly understand the regularity and morphology of QRS waves, QRS time is not wide, normal shape, indicating that excitability originates from the atrioventricular bundle Above, from the sinus node, atrium or junction area, collectively referred to as supraventricular; if the QRS is widened, the shape is singular, then the ventricular septum from the atrioventricular bundle branch, measuring whether the RR interval is equal, find out the premature beat or escape Beat, then analyze the relationship between P wave and QRS wave, whether after each P wave, whether it follows the QRS wave, whether the PR interval is fixed, the main rhythm is determined by the above ECG analysis, it is sinus rhythm or ectopic heart rhythm, ectopic heart rhythm Should be aware of the initiative or passive, from the atrium, the handover area or the ventricle, while paying attention to whether there is interference or conduction block, etc., in the analysis of ECG fashion should pay attention to whether there is baseline instability, etc., so as to avoid false errors Arrhythmia.

For complex arrhythmia, a more obvious P-wave guide should be selected for longer tracing. Generally, II or aVF lead is used for synchronous tracing, which is convenient for analyzing the regularity and morphology of P wave. For example, conventional ECG lead P wave is not Obviously, the S5 or CR1 lead can be added to show the P wave. The former negative (red) is placed on the sternum handle, and the positive (yellow) is placed on the fifth intercostal space on the right edge of the sternum. The lead selection button is dialed to the I lead. Position tracing; the latter placed the negative (red) on the right forearm and the positive (yellow) on the fourth intercostal space on the right sternal border, also taking the I lead position.

2.24h dynamic electrocardiogram

Also known as Holter monitoring, it is a method of recording electrocardiogram continuously for 24 to 72 hours under active conditions, which can improve the detection rate of arrhythmia. It has been widely used in the diagnosis of arrhythmia and the effect of drug treatment. No routine rhythm is found in conventional electrocardiogram. Abnormalities, such as monitoring with dynamic electrocardiogram for 24h, may detect premature contraction, paroxysmal tachycardia, intermittent arrhythmia such as conduction block, dynamic electrocardiogram can also be quantitative analysis to determine the number of abnormal heart rhythm; The total number of pre-systolic contractions and the percentage of total heartbeat within 24 hours; the number of occurrences of paroxysmal tachycardia; and the number of heartbeats per continuous duration, in addition, asymptomatic arrhythmias can be found; observed symptoms Relationship with arrhythmia; and whether arrhythmia is induced by activity or occurs in silence, and pediatrics are often used in the following situations:

(1) Prevention of sudden death caused by arrhythmia after congenital heart disease: 11 cases of aortic dislocation after dynamic electrocardiogram monitoring, 7 cases of sick sinus syndrome, timely application of pacemaker can prevent Sudden death after surgery.

(2) Diagnosis of sick sinus syndrome: It can be confirmed by dynamic electrocardiogram that there is severe sinus bradycardia or supraventricular tachycardia, thus avoiding sinus node function examination.

(3) to find the cause of syncope: bradycardia or tachycardia can cause syncope, unexplained syncope patients by dynamic electrocardiogram examination, found that 10% to 25% caused by arrhythmia.

(4) Evaluation of the efficacy of antiarrhythmic drugs: ventricular premature contraction itself varies greatly, conventional electrocardiogram can not reflect the real situation, it is generally believed that after 24h dynamic electrocardiogram examination, the ventricular premature contraction after taking the drug is reduced by more than 50% compared with before administration. To be effective, more than 90% is effective, and it can also guide reasonable dosage time, dosage, etc.

(5) Checking the pacemaker failure: Intermittent dysfunction occurs in the pacemaker, and dynamic electrocardiogram monitoring is required to detect the 24h dynamic electrocardiogram monitoring results of healthy children of different ages.

3. Transesophageal atrial pacing check

The lower end of the esophagus is close to the left atrium, so the method is indirect left atrial pacing. In recent years, pediatrics has been widely used in cardiac electrophysiological examination, and the clinical application is as follows:

(1) Examination of sinus node function: The recovery time of sinus node can be measured, the recovery time of sinus node and the time of sinus conduction can be corrected. The normal values of children are (913.3±139.7) ms, (247.7±51.3) ms and (102.5 ±18.6) ms.

(2) evaluation of atrioventricular conduction function: can measure the Venturi block, 2:1 block point, atrioventricular function refractory period and effective refractory period.

(3) Detection of atrioventricular nodal pathway: 23.6% of normal children have atrioventricular nodal pathways.

(4) Study of the reentry mechanism of supraventricular tachycardia: transesophageal atrial pacing can induce sinus node, intraventricular, atrioventricular junction and atrioventricular bypass reentry supraventricular tachycardia, synchronous esophageal electrocardiogram And V1 lead ECG, can distinguish P wave morphology, atrial activation sequence, determine RP, PR interval and atrioventricular conduction curve, identify different reentry mechanisms of supraventricular tachycardia, and choose effective drug treatment.

(5) For the pre-excitation syndrome, the following examinations can be performed: the atrioventricular accessory pathway is detected, and the recessive pre-excitation syndrome is diagnosed; the bypass refractory period is measured, the high-risk patient is initially screened, and the child bypass refractory period is <220 ms. When the incidence of atrial fibrillation is high, it is easy to cause ventricular fibrillation and is a high-risk patient.

(6) termination of supraventricular tachycardia episodes: the use of esophageal atrial pacing overspeed suppression method.

(7) Study efficacy: study the electrophysiological effects of antiarrhythmic drugs and observe the efficacy.

4. His bundle electrogram and intracardiac electrophysiological examination

Traumatic examination, His's beam electrogram is the potential map generated by the atrioventricular bundle excitation. The electrode is inserted into the right heart chamber through the vein, directly contacts the atrioventricular bundle, and records the excited electric wave, which is the His bundle beam diagram.

(1) Significance of each interval: The meaning and measurement of each phase of the Histogram of the beam is as follows:

1P-A interval: the distance from the beginning of the P-wave of the surface electrocardiogram to the starting point of the high-definition wave of the A-wave of the Histz electrogram is called the PA interval, reflecting the activation from the upper part of the right atrium to the lower part of the right atrium. The conduction time near the junction of the atrioventricular node is 20 to 40 ms.

2A-H interval: The distance from the starting point of the high wave of the A wave to the starting point of the H wave is called the AH interval, reflecting the conduction time from the lower right atrium to the atrioventricular node to the His bundle, normal value It is 60 to 140ms.

3H wave: a narrow two-way or three-way wave that lasts for 20 ms, reflecting the conduction time in the His bundle.

4H-V interval: the distance from the start of the H wave to the start of the V wave or the surface of the QRS wave of the surface electrocardiogram, called the HV interval, reflecting the excitatory from the bundle of the bundle of the atrioventricular bundle, the Puye fiber to the ventricular muscle The conduction time, the normal value is 35 ~ 55ms, the HV interval is the Hepu transmission time.

(2) His's beam diagram is used to:

1 Determining the location of atrioventricular block: According to the characteristics of His bundle electrogram, the location diagnosis of atrioventricular block is divided into His bundle above (main atrioventricular node level), within His bundle and below His bundle .

2 to determine the origin of ectopic beats and ectopic heart rhythms.

3 Identification of supraventricular tachycardia with indoor differential conduction and ventricular tachycardia.

5. Intracardiac electrophysiological examination

Inserting a lead into the heart chamber to record and/or stimulate different parts of the heart for electrophysiological studies can determine the precise location of the conduction block and the mechanism of tachycardia. Currently, it is often used in combination with tachycardia for radiofrequency ablation. The exact diagnosis of the mechanism of occurrence.

The indications for intracardiac electrophysiological examination are:

(1) Defining the pathogenesis of supraventricular tachycardia and ventricular tachycardia, understanding the reentry loop, abnormal bypass or autonomic lesions, facilitating treatment, atrioventricular reentry and atrioventricular nodal reentry type supraventricular tachycardia Atrial flutter caused by reentry, ectopic atrial tachycardia and idiopathic ventricular tachycardia can be cured by radiofrequency ablation.

(2) High-risk children with sudden death or severe arrhythmia: sudden death after several years of congenital heart disease, mostly caused by severe ventricular arrhythmia, such as postoperative rehabilitation of children with tetralogy of Fallot, hemodynamic examination Normal, intracardiac electrophysiological examination can induce ventricular tachycardia, prone to sudden death, and timely treatment with drugs.

(3) Evaluation of high-risk patients with pre-excitation syndrome: Pre-excitation syndrome bypass pre-transmission effective refractory period 220ms, or when atrial fibrillation occurs, ventricular rate up to 200 times / min, can predict sudden death or cardiac arrest.

(4) Patients with unexplained syncope: Intracardiac electrophysiological examination may indicate severe bradycardia or tachycardia, thus guiding specific treatment.

(5) Study anti-arrhythmia drugs: study the electrophysiological effects of anti-arrhythmia and observe the effect.

Although intracardiac electrophysiological examination is relatively safe, the laboratory should have all emergency medicines and equipment, including cardiopulmonary resuscitation, defibrillators, etc., in case of any accident.

Diagnosis and differential diagnosis of neonatal arrhythmia

diagnosis

Arrhythmias are primarily diagnosed by electrocardiography, but most cases can be diagnosed by medical history and physical examination.

1. Arrhythmia electrocardiogram diagnostic analysis method

Electrocardiogram is of great significance for the diagnosis of arrhythmia, and often plays a decisive role in diagnosis. However, some arrhythmia are complicated or mixed with several types of arrhythmia, which makes it difficult to diagnose. Therefore, analyzing the arrhythmia ECG must be progressive according to certain rules. If necessary, it is necessary to analyze by means of a ladder diagram.

(1) ECG analysis method:

1P wave: firstly determine whether there is P wave in the conventional lead, and then judge the source of the excitation according to the shape, direction, velocity and regularity of the P wave and the relationship with the QRS complex. The sinus P wave is obtusely round. In the I, II, aVF, V5 lead erect, the aVR lead is inverted, the V1 lead is bidirectional, the rate varies with age, and the normal range of heart rate per minute is as follows: 110 to 150 times under 1 year old, 1~ 3 years old 90 to 130 times, 3 to 6 years old 80 to 120 times, 6 years old and above 60 to 100 times.

2P-R interval: With age and heart rate changes, the younger the age, the faster the heart rate, the shorter the PR interval, the shortest is 0.08s, and the longest is 0.18s.

3QRS wave group: analysis of the shape and interval of QRS complexes, help to determine the location of ventricular impulse formation and the excitatory process in the ventricle. If the shape and time limit of the QRS complex are normal, it can be determined as supraventricular stimuli. Downstream, if the QRS complex is malformed, it may be ventricular rhythm, bundle branch block, indoor block, supraventricular ventricular ventricular differential conduction or pre-excitation syndrome.

Then further analysis of the QRS complex is intermittent or continuous occurrence, its relationship with the P wave and the PR interval, in order to determine the type of arrhythmia.

(2) Application of ladder diagram in the diagnosis of arrhythmia: In the analysis of more complicated arrhythmia, according to the characteristics of electrocardiogram, graphically illustrate the origin of the activation and the conduction process, and the ladder diagram is a horizontal diagram. A schematic diagram of lines drawn by vertical lines and diagonal lines, usually in three rows, representing the atrium (A), the atrioventricular junction (AV) and the ventricle (V), and the vertical lines in the A and V rows from top to bottom. The P-wave and the QRS complex are respectively aligned, the oblique line in the AV line indicates the conduction process of the impulse in the atrioventricular junction, and the oblique line to the lower right indicates the impulse forward conduction, indicating to the upper right oblique line. Impulsive reverse conduction, black dots indicate the origin of excitement, and "" indicates conduction is blocked.

When analyzing complex arrhythmia, it is sometimes necessary to show the sinus conduction relationship. In this case, it is necessary to increase the S line above the A line, and the SA between the S line and the A line. It is necessary to show the excitation in the intraventricular conduction, under the V line. Increase EV line and E line.

2. Various types of arrhythmia ECG features

(1) Sinus tachycardia: The upper limit of sinus heart rate in term infants is 179-190 beats/min, and the upper limit of premature infants is 195 beats/min.

The 1P wave occurs regularly, which is a sinus P wave, that is, the I, II, aVF leads are upright, the aVR lead is inverted, and the P wave of the same lead has the same shape.

The 2P-R interval is not shorter than 0.08 s (the minimum interval for normal neonatal PR interval).

3 The PR interval between the same leads is <0.12s.

(2) Sinus bradycardia: The electrocardiogram has the characteristics of sinus rhythm. The lower limit of sinus heart rate in full-term children is 90 beats/min.

(3) sinus node dysfunction:

1 electrocardiogram: mainly manifested as recurrent sinus bradycardia, abnormal P wave morphology, sinus arrest, sinus block, slow-fast syndrome (ie, supraventricular rapid on the basis of slow heart rhythm) Ectopic rhythm, such as supraventricular tachycardia, atrial flutter, tremor, etc.).

2 confirmed by the atropine test and esophageal atrial pacing to measure sinus node function.

A. Atropine test: pre-test tracing electrocardiogram, then intravenous injection of atropine 0.02mg / kg, immediately after the injection, 1, 3, 5, 7, 10, 15, 30min each recorded II lead ECG, such as heart rate after injection Increase or increase does not exceed 25% of the original heart rate, or new arrhythmia such as sinus bradycardia, sinus block after the test, sinus arrest, knot escape, etc. to support the diagnosis of this disease .

B. Esophageal atrial pacing test sinus node function: neonatal esophageal atrial pacing test sinus node function parameters need further study.

(4) paroxysmal supraventricular tachycardia electrocardiogram: 3 or more consecutive and rapid supraventricular (atrial or borderline) pre-contraction, RR interval rules, atrial sex may have P' Wave, no one has a P' wave or a reversed P', but because the heart rate is too fast, the P' wave is often difficult to identify, so it is collectively called paroxysmal supraventricular tachycardia. The QRS form is mostly normal, but Deformation due to indoor differential conduction, tachycardia at the time of onset may cause insufficient blood supply to the myocardium, resulting in a decrease in ST segment and a low or inverted T wave.

(5) Paroxysmal ventricular tachycardia electrocardiogram: more than 3 consecutive ventricular premature contractions, QRS broad and wide deformity, T wave and main wave direction opposite, visible sinus P wave independent of QRS wave, ventricular rate 150 to 200 times / min.

(6) Premature beat electrocardiogram: Prenatal neonatal contraction is divided into atrial, borderline and ventricular according to its origin in the atrioventricular, atrioventricular junction and ventricle. Its ECG features are:

1 atrial contraction before contraction:

The AP' wave is advanced and the morphology is different from the sinus P wave.

BP'-R interval > 0.10 s.

C. The P' wave appearing before the period may be followed by a normal QRS wave or a QRS wave (not transmitted) or a mildly deformed QRS wave (indoor differential conduction).

D. Incomplete compensation compensation interval.

2 borderline pre-contraction:

A.QRS appears in advance and has the same shape as normal.

There is no P' wave or reversed P wave before and after B. QRS (P'-R interval <0.10s, RP' interval <0.20s).

C. Complete compensatory interval.

3-ventricular premature contraction:

A. The QRS wave that appears in advance has no P wave before it.

B.QRS wave width deformity, the time limit is >0.10s, and the T wave is opposite to the main wave.

C. Complete compensatory interval.

(7) Atrioventricular block ECG:

1 once atrioventricular block: the prolongation of the PR interval, the highest value of the normal neonatal PR interval is 0.12 s, above which the value can be considered as one-time atrioventricular block.

2 second degree atrioventricular block: divided into type I and type II.

Type I: The PR interval is gradually prolonged, and the last sinus agitation is completely blocked. The QRS falls off and is later passed down again.

Type II: The PR interval is constant, and the QRS is proportionally shedding, which is 3:1, 2:1, 4:3, and the like.

3. Third degree atrioventricular block P is not related to QRS, ventricular rate is slow and regular, 40 ~ 60 times / min, QRS wave shape depends on the position of the secondary rhythm point, the lower the secondary rhythm point position, QRS The wider the deformity, the worse the prognosis.

Differential diagnosis

Various types of arrhythmia identification are described in the above clinical manifestations and auxiliary examinations.

The differential diagnosis of paroxysmal supraventricular tachycardia is as follows:

1. Identification with sinus tachycardia

(1) Paroxysmal supraventricular tachycardia is well-balanced, with a heart rate variation of <1 to 2 times per minute, and sinus tachycardia is uneven.

(2) supraventricular tachycardia heart rate is faster, generally 230 ~ 320 times / min, and sinus tachycardia is generally less than 220 times / min.

(3) Supraventricular tachycardia is an ectopic rhythm with a sudden onset and abrupt termination, while sinus tachycardia heart rate changes are gradual.

(4) The method of stimulating the vagus nerve in the onset of supraventricular tachycardia can suddenly terminate the episode, or be ineffective, and the sinus tachycardia can only slow the heart rate slightly.

2. Identification with ventricular tachycardia

(1) Supraventricular tachycardia with ventricular tachycardia may be similar to ventricular tachycardia, but electrocardiogram often shows a pattern of bundle branch block, that is, the V1 lead is mostly "M" shape, V5 lead There are deep wide S waves.

(2) The supraventricular tachycardia may have a P' wave associated with the QRS wave before or after the QRS wave, and there may be no P' wave before and after the ventricular tachycardia QRS, and sometimes there is no sinus P associated with it. The sinus P wave is captured and the ventricle is captured.

(3) supraventricular tachycardia rhythm is neatly arranged, heart rate is fast; and ventricular tachycardia rate is slightly slow, generally 150 ~ 180 times / min, ventricular rate has mild irregularities.

(4) Seizure gap, supraventricular tachycardia see atrial or borderline premature contraction, while ventricular tachycardia see ventricular premature contraction.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.