Atrial septal defect in children

Introduction to atrial septal defect in children Atrialseptaldefect (ASD) refers to the traffic that causes atrial level at any part of the atrial septum. It refers to the presence of a hole in the interatrial septum except for the patent foramen ovale. Simple atrial septal defect is one of the most common congenital heart diseases, and the incidence rate is about 0.6 of live births. Most of them are sporadic and have a family-like tendency. Holt-Oram syndrome is associated with upper limb (tibia) malformation of ASD, atrial septal defect due to endocardial pad development disorder is located in the lower part of the atrial septum, and the primary atrial septal defect (ostiumprimordium ASD) above the atrioventricular valve is not included in this Within the scope of the disease. basic knowledge The proportion of sickness: 0.00025% Susceptible people: children Mode of infection: non-infectious Complications: pneumonia heart failure pediatric infective endocarditis

Causes of atrial septal defect in children

(1) Causes of the disease

Environmental factors for fetal development (32%):

1. Infection, viral or bacterial infections in the first three months of pregnancy, especially rubella virus, followed by Coxsackie virus, which has a higher incidence of congenital heart disease in infants born.

2. Others: such as amniotic membrane lesions, fetal compression, early pregnancy threatened abortion, maternal malnutrition, diabetes, phenylketonuria, hypercalcemia, radiation and cytotoxic drugs in early pregnancy, mothers are too old, etc. The possibility of congenital heart disease in the fetus.

Genetic factors (25%):

Most congenital heart disease is formed by the interaction of multiple genes with environmental factors. Especially chromosomal translocations and aberrations.

Other factors (24%):

Some congenital heart diseases are more common in the highlands, and some congenital heart diseases have significant differences between men and women, indicating that the altitude and gender of the birthplace are also related to the occurrence of this disease.

(two) pathogenesis

Pathological anatomy

According to the defect site, the atrial septal defect can be divided into:

(1) secondary atrial septal defect (secundum ASD) is the most common, accounting for 62% to 78.8% of all atrial septal defects. The diamond defect is located in the real atrial septum separating the left atrium and the right atrium, that is, in the center of the interatrial septum. The edge of the defect may be the follicular fossa formed by the lower limbs on the second atrial septum, also known as the fossa ovale atrial septal defect (Fig. 1), the size of the defect varies, the shape is different, single or multiple, large There may be residual strip-like atrial septal tissue in the middle of the defect, and there is also a mesh-like shape.

(2) venous sinus atrial septal defect (sinus venous ASD) superior vena cava ASD, accounting for 5.3% to 10% of all ASD, the defect is located in the posterior superior part of the fossa ovalis, the junction of the right atrium and the superior vena cava, often With right venous connection (Figure 1), inferior vena cava ASD, relatively rare, accounting for about 2%, the defect is located in the posterior orbital of the fossa ovalis, the junction of the right atrium and the inferior vena cava, can be associated with pulmonary ectopic connection .

ASD can be combined with other congenital heart diseases, such as ventricular septal defect, patent ductus arteriosus, pulmonary stenosis, etc., because ASD is a blood flow diversion pathway for many complex congenital heart diseases, common in complete transposition of the great arteries, tricuspid valve Atresia, complete pulmonary venous connection, etc., superior vena cava ASD is often associated with partial pulmonary venous connection, up to 80% to 90%, mostly for the right pulmonary vein, followed by alopecia ASD with mitral valve prolapse accounting for about 17% .

2. Pathophysiology

The normal left atrial pressure (5 ~ 10mmHg) is slightly higher than the right atrium (2 ~ 4mmHg), the left-to-right shunt of the atrial septal defect depends mainly on the left and right ventricular filling resistance, the right ventricular compliance is better than the left ventricle The right ventricular filling resistance is low. Therefore, there is a left-to-right shunt in the atrial septal defect in the diastolic phase and early contraction. The baby's right ventricle is thicker and the compliance is poor. The left-to-right flow of the baby's ASD is not much. Age-increasing sub-flow gradually increased, which in turn caused right atrium, right ventricle enlargement, pulmonary artery widening, pulmonary hypertension mostly occurred in older children, combined with severe pulmonary hypertension can lead to right-to-left shunt of ASD and cyanosis, occasionally, lower cavity The venous valve leads the inferior vena cava blood to the left atrium through the ASD flow.

Pediatric atrial septal defect prevention

The occurrence of congenital heart disease is a comprehensive result of various factors. In order to prevent the occurrence of congenital heart disease, publicity and education of popular science knowledge should be carried out, and key populations should be monitored to give full play to the role of medical staff and pregnant women and their families.

1. Get rid of bad habits, including pregnant women and their spouses, such as smoking, alcohol and so on.

2. Actively treat diseases affecting fetal development before pregnancy, such as diabetes, lupus erythematosus, anemia, etc.

3. Actively do prenatal checkups to prevent colds. Try to avoid using drugs that have been proven to have teratogenic effects and avoid contact with toxic and harmful substances.

4. For older women, there is a family history of congenital heart disease, and one of the couples with serious diseases or defects should be monitored.

Complications of atrial septal defect in children Complications, pneumonia, heart failure, infective endocarditis

The disease is often complicated by pneumonia, heart failure, bacterial endocarditis and Eisenmenger syndrome, and can be complicated by atrial fibrillation and embolism.

Symptoms of atrial septal defect in children Symptoms Symptoms of systolic murmur atrial septal defect repeated upper respiratory tract infection

Symptom

Most atrial septal defect infants are neglected asymptomatic. A few may have growth retardation, repeated upper respiratory tract infections or even heart failure. Generally, soft systolic murmurs are available 6 to 8 weeks after birth, and sometimes 2nd heart sounds are fixed. The division is more diagnosed when the patient is 1 to 2 years old. The children with moderate left to right shunt are asymptomatic. Even if there are symptoms, they are mostly mild fatigue and shortness of breath. Only children with large flow rate appear obvious. Shortness of breath and fatigue, and increase with age.

2. Signs

Physical examination revealed a bulge in the anterior region of the heart. When the left-to-right shunt was evident in the elderly or adult atrial level, the apical beat was evident.

(1) A typical second tone is fixedly split.

(2) A soft systolic murmur can be seen between the second ribs on the left side of the sternum.

(3) In the left lower sternal border, the early-intermediate diastolic murmur is available. The reason for the second heart sound splitting is related to the following two reasons: (1) due to the increase in right ventricular systolic stroke volume during atrial septal defect, the pulmonary valve The second tone is delayed, 2 due to the obvious expansion of the pulmonary artery, the intra-arterial tension rise of the pulmonary artery is delayed, and the pulmonary valve closure is delayed. Because the blood flow through the pulmonary valve is significantly increased, the upper edge of the left sternum can be sprayed. The murmur is transmitted to the lungs, and the atrial horizontal left-to-right shunt increases the blood flow through the tricuspid valve during diastole, resulting in diastolic early-middle murmur in the tricuspid region.

Pediatric atrial septal defect examination

Under normal circumstances, routine examination is normal, such as pulmonary infection, endocarditis, bloody infection, increased erythrocyte sedimentation rate, anemia, blood culture positive.

Electrocardiogram

Usually normal sinus rhythm, in the elderly can have borderline rhythm and supraventricular tachycardia, the vast majority of the electrical axis between 95 ° and 170 °, due to intra-atrial and His bundle ventricular myocardium conduction delay In the elderly, the PR interval is prolonged, and I° atrioventricular block is present. Nearly half of the patients may have P wave changes. In almost all cases, there are different degrees of V1 lead rsR' or RSR' incomplete right bundle. The performance of branch block is accompanied by a large right ventricle.

2. Chest X-ray

The heart usually expands, and the ratio of cardiothorax is >0.5. Pulmonary vascular shadow increases with age and left-to-right sub-flow. When pulmonary vascular obstructive disease occurs, the main pulmonary artery is enlarged and the peripheral lung field is rare.

3. Echocardiography

(1) Two-dimensional echocardiography: 1 Direct signs: A. In the apical four-chamber view, because the ultrasound beam is almost parallel with the interatrial septum, it is easy to produce echo loss. The two-chamber view and the four-chamber view are the best cuts because The sound beam is almost perpendicular to the interatrial septum, and combined with the parasternal four-chamber view and the short-axis view of the aorta to help detect, and multiple sections are combined to diagnose, the free end of the atrial septal defect is spherical thickening, shaped like a match head, and Called the "T" sign, this feature clearly identifies the location, size and number of defects, B. Defining the relationship between all pulmonary veins and left atrium to exclude venous venous drainage, 2 indirect signs: right atrium, right ventricular enlargement The pulmonary artery is widened, the ventricular septal motion is flat or in the same direction as the posterior wall of the left ventricle.

(2) Pulse Doppler ultrasound: Position the sampling volume on the right atrium side of the shunt, pay attention to make the blood flow direction and the angle of the sound beam as small as possible, generally get 1 to 3 positive waves and 1 contraction in the diastolic phase. In the early negative wave, the maximum flow velocity is generally below 1.3m/s, the flow rate of the tricuspid valve is increased, and the flow velocity of the transpulmonary artery is accelerated, but it is rarely more than 2.5m/s. If it is more than the pulmonary valve stenosis.

(3) Color Doppler flow imaging: usually the left atrial pressure is higher than the right atrium, so it can show the blood flow from the left atrium into the right atrium, the blood flow is located in the middle of the septum, the upper part or multiple shunts The bundle, in order to determine the type of defect, can also estimate the size of the flow, the size of the defect, pay attention to the degree of shunt is not completely dependent on the defect is too small, it is important depends on the compliance of the right ventricle, it is worth noting that the left upper chamber Residual patients can easily coexist with coronary sinus atrial septal defect combined with color Doppler and other clinical examinations to avoid missed diagnosis.

(4) Three-dimensional echocardiography: Two-dimensional ultrasound can only display the atrial septal defect and the direction and size of the shunt beam from the planar structure. It is necessary to observe two-dimensional images of different azimuths to imagine the overall shape of the atrial septal defect. The stereoscopic anatomical relationship of the adjacent structure is usually very difficult and inaccurate. The three-dimensional echocardiography can observe the characteristics of the atrial septal defect in a three-dimensional perspective, the spatial position and its spatial relationship with the surrounding structure, from the right heart. The lateral (L2a) or left flank (L1a) directly observed the overall shape, size, size and adjacent structure of the superior vena cava, inferior vena cava, coronary sinus, etc., and can not observe the two-dimensional echocardiography. The displayed area varies with the dynamic change of the cardiac contraction symmetric contraction, so that the comprehensive pathological diagnosis of atrial septal defect, correct classification and accurate measurement of defect size (Figure 2), as early as 1993, Belohlavek et al reported three-dimensional ultrasound pairs Normal and abnormal atrial septum can be well shown, and the study has been more intensive since then. In Marx et al, 13 of 16 patients with atrial septal were enrolled. Successful dynamic three-dimensional reconstruction, and can observe the characteristics of the defect, spatial position and its spatial relationship with the surrounding structure from three-dimensional perspective, such as the relationship between aortic valve and atrial septum, the normal connected pulmonary vein entrance, etc.; DallAgata et al. The surgically repaired II-hole atrial septal for transthoracic and transesophageal dynamic three-dimensional reconstruction, found that the correlation with surgery is as high as 0.90 or more, it is also found that the II-hole type of housing deficiency is not a simple hole between the two rooms, from the right atrium On the side, it exists in a relatively independent folded area on the interatrial septum, and also has a three-dimensional structure. Many studies have shown that three-dimensional ultrasound can provide more detailed spatial activity information of the heart anatomy, thereby improving the diagnosis of atrial septal defect. Correctness.

4. Cardiac catheter and angiography

Usually, for the diagnosis of secondary atrial septal defect, cardiac catheterization is not necessary. It is only suspected to have pulmonary obstructive disease or other complicated malformation. In cardiac catheterization, if the oxygen saturation of the right atrium is significantly higher than above, Inferior vena cava (>10%) should be considered for the presence of atrial septal defect, but ventricular septal defect with tricuspid regurgitation, left ventricular right atrial shunt, partial or complete atrioventricular septal defect, pulmonary venous ectopic drainage to Right atrium or vena cava or systemic arteriovenous fistula can lead to elevated atrial oxygen saturation.

In large atrial septal defect, the systolic or mean pressure of the left and right atrium is equal, and the right ventricular pressure is slightly elevated, mostly at 25-35 mmHg. In a few children, there may be a right ventricular pressure rise, sometimes between the right ventricle and the pulmonary artery. The pressure gradient of 15 to 30 mmHg was measured, and the pulmonary artery pressure was normal or slightly elevated. Under normal circumstances, the pulmonary artery resistance was below 4.0 Um2.

5.CT and MRI

Simple atrial septal defect generally does not require CT and MRI. CT and MRI can be used to determine whether there is atrial septal defect by observing whether the interatrial continuity is interrupted. To avoid false positives, the interatrial septum is usually observed in two consecutive levels. Continuous interruption or continuous interruption of interatrial septum observed at two different scanning angles for CT and MRI diagnosis of atrial septal defect. CT examination must be injected with contrast agent. MRI examination generally uses spin echo T1W image to observe the room. Whether the interval continuity is interrupted (Fig. 3), if abnormal blood flow is found in the gradient echo movie sequence at the same time, it is a reliable basis for the diagnosis of atrial septal defect. The contrast-enhanced magnetic resonance angiography sequence is helpful for the diagnosis of atrial septal defect. Not large, but it is helpful to determine whether there is a partial partial anomalous pulmonary venous connection. In addition to the direct signs of continuous interruption of the interatrial septum, CT and MRI can clearly show the right atrial enlargement and right ventricular enlargement. Indirect signs of atrial septal defect such as pulmonary artery dilatation.

6. Cardioangiography

The right heart angiography catheter is placed in the right superior pulmonary vein or the left atrium. The liver lock position is 40° to the left anterior oblique angle, and the head is 40° angled. Because the interatrial septum is obliquely oriented, in the left anterior oblique position and the liver lock position. The room is tangential, showing good results. At the same time, the 40° projection to the head can project the left and right atrium at the rear to the head end, separated from the left and right ventricles, because the blood from the right pulmonary vein mainly flows along the interatrial septum. The right upper pulmonary venography of the liver lock can best outline the atrial septum, showing the direct sign of the atrial septal defect. The right upper pulmonary vein of the contrast agent is first developed. It can be seen that the contrast agent enters the right atrium through the defect along the left edge of the interatrial septum. Show the location of the atrial septal defect and the size of the defect. Cardiac angiography of the atrial septal defect should be seen when the contrast agent enters the right ventricle, the pulmonary artery, and the lung is developed after the pulmonary circulation. If there is a part of the pulmonary vein ectopic connection, the selective pulmonary vein must be used. When angiography or pulmonary angiography, right upper pulmonary vein or left atrial angiography of the liver lock, direct signs of various atrial septal defects can be displayed, the size can also be measured, and can be based on The location of the atrial septal defect diagnosis (Figure 4), when the defect is located in the upper part of the interatrial septum, and the superior vena cava is also developed, the upper cavity type atrial septal defect; when the defect is located in the middle of the interatrial septum, or from the middle of the interatrial septum When extending below, it is a fossa ovalis or secondary hole (central) atrial septal defect; when the defect is located in the lower part of the interatrial septum, it is a primary atrial septal defect.

Diagnosis and diagnosis of atrial septal defect in children

diagnosis

Pulmonary valve area has soft systolic murmur, fixed second sound split, incomplete electrocardiogram, right ventricular bundle block and pulmonary vascular shadow deepening and other X-ray findings, suggesting the possibility of atrial septal defect, ultrasound Cardiogram and cardiac catheterization can confirm the diagnosis.

Differential diagnosis

The disease should be differentiated from functional murmur, pulmonary stenosis, pulmonary venous drainage, and ventricular septal defect.

1. Functional murmur: its systolic murmur is short, there is no fixed second tone splitting and electrocardiogram, X-ray examination and cardiac ultrasound can help identify.

2. Pulmonary stenosis: the sound is loud, jetting, often accompanied by tremor, P2 is reduced or absent, X-ray shows rare lung texture, clear lung field, right heart catheterization can find systolic pressure difference between right ventricle and pulmonary artery .

3. Pulmonary vein ectopic drainage: described below.

4. Ventricular septal defect: the location of the murmur is low, and more often accompanied by tremor. In addition to right ventricular hypertrophy, the left ventricle is also often hypertrophied. Cardiac ultrasound and right heart catheterization can help diagnose.

5. The original patent hole is not closed: it is very similar to the clinical manifestation of the patent hole in the atrial septal defect. The apex of the atrial septal defect and the reflux systolic murmur, the left axis of the electrocardiogram, the prolongation of the PR interval or the incompleteness Right bundle branch block, the primary hole is not suspected, 2D ultrasound or right heart catheter examination shows that the defect is lower, near the tricuspid valve, the right atrial blood oxygen content is increased, the right ventricle is higher, Doppler ultrasound or cardiovascular angiography can clarify changes in the atrioventricular pathway or mitral regurgitation.

6. Atrial septal defect combined with malformation:

(1) Lutembacher syndrome: atrial septal defect with mitral stenosis, cardiovascular angiography can be diagnosed.

(2) atrial septal defect with pulmonary stenosis (Fala triplet): 10% to 15% of atrial septal defect with pulmonary stenosis, pulmonary valve area sounds bright and rough, tremor, P2 weakened or disappeared, V1 lead R The wave is higher than 1.6mV, and the right heart catheterization can confirm the diagnosis.

(3) atrial septal defect with ventricular septal defect: more severe than simple atrial septal defect, clinical manifestations similar to ventricular septal defect with pulmonary hypertension, electrocardiogram showed biventricular thickening, ECG axis more right, the diagnosis depends on cardiac catheterization and Cardioangiography.

(4) atrial septal defect with pulmonary venous venous drainage: about 15% of atrial septal defect with venous venous drainage, clinical manifestations and atrial septal defect similar, but to a lesser degree, the diagnosis depends on cardiac catheterization and cardiovascular imaging.

(5) Single atrium: the atrial septum is completely absent, the left and right atrium are not divided, the blood is mixed, and there are many mild cyanosis. The clinical manifestations are similar to the complete endocardial cushion defect. The cardiac catheter is used to examine the left atrium, the right atrium, and the double ventricle. Pulmonary artery, aortic blood oxygen concentration is almost equal, Doppler ultrasound and cardiovascular angiography can help diagnose.

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