Atrial septal defect

Introduction Atrial septal defect (ASD) is a clinically common congenital heart malformation. It is an abnormality in the original atrial septum during embryonic development, resulting in residual pores between the left and right atrium. Atrial septal defect can occur alone or in combination with other types of cardiovascular malformations. Women are more common, and the ratio of male to female is about 1:3. Due to the presence of shunt at the atrial level, corresponding hemodynamic abnormalities can be caused.

Cause

Like other congenital heart diseases, it is currently believed to be the result of interactions between complex relationships such as genetic and environmental factors. The following factors may affect the development of the fetus and produce congenital malformations.

(1) Environmental factors for fetal development:

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

Others: lesions such as amniotic membrane, 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.

(2) Genetic factors:

Most congenital heart disease is formed by the interaction of multiple genes with environmental factors.

(3). Other:

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.

Among the patients with congenital heart disease, there are very few cases that can be found, but the health care for pregnant women is strengthened, especially in the early pregnancy, actively preventing rubella, influenza and other rubella virus diseases and avoiding all the factors related to the disease. Congenital heart disease is positive.

an examination

Physical examination

Most of the body development is normal. The right ventricle expands, and as the age increases, the contours of the adjacent sternum and left ribs can be shown to be swelled. Percussion can be found to enhance the lifting power. At the time of percussion, the heart can be enlarged, especially in the second and third intercostals of the left chest due to pulmonary artery expansion.

2. Radiological examination

The main signs of radiation are:

1 heart enlargement, especially the right atrium and right ventricle are most obvious, this is in the right anterior oblique position. It is more clear.

2 The pulmonary artery segment is prominent, the hilar shadow is deepened, the lung field is congested, and the hilar dance is sometimes seen under fluoroscopy. In advanced cases, calcification may be formed.

3 The aortic arch is reduced (Fig. 33-06). In addition, there is no left ventricular enlargement in the general case, which can be distinguished from ventricular septal defect or patent ductus arteriosus.

3. ECG examination

Typical atrial septal defect often shows an increase in P wave and a right deviation of the electrical axis, often between +60 and +180 degrees. In most cases, there may be incomplete or complete right bundle branch block and right ventricular hypertrophy, and those with pulmonary hypertension may have right ventricular strain. The frontal surface vector shows that the QRS ring is indexed in the clockwise direction, and the body of the ring is located below the X axis.

4. Cardiac catheterization

Cardiac catheterization is an effective diagnostic method for atrial septal defect. At present, most scholars believe that in suspicious or serious cases, the cardiac catheter should be inserted from the saphenous vein of the lower extremity, and it is easy to enter the left atrium through the defect, and the passing rate is as high as 85%. However, for cases of superior cavity type defect, it is convenient to take the approach of upper extremity vein insertion.

Differential diagnosis

According to typical physical signs and laboratory tests, the diagnosis is not difficult, but it needs to be identified.

(1) Patients whose signs are not obvious should be differentiated from normal physiological conditions: if only the second intercostal space on the left sternal border is heard and the second-grade systolic murmur is accompanied by a second heart sound splitting or hyperthyroidism, then It is also common in normal children. At this time, if X-ray, electrocardiogram, and echocardiography are found to have signs of the disease, further diagnosis of right heart catheterization may be considered.

(2) Large ventricular septal defect: the left-to-right sub-flow is large, and its X-ray and ECG performance can be very similar to the disease. The physical signs may also have the second heart sound of the pulmonary valve region. Caused the difficulty in differential diagnosis.

However, the position of the ventricular septal defect is low, often in the third and fourth intercostals of the left sternal border, and more with tremor, the left ventricle often increased and so on. However, in children, especially the identification of the first hole of the patent is still not easy, at this time, echocardiography, right heart catheterization, etc. help to establish a diagnosis.

In addition, left ventricular-right atrial communication (a special type of ventricular septal defect) patients with signs similar to high ventricular septal defect, right heart catheterization results similar to atrial septal defect, also pay attention to identification.

(C) valvular simple pulmonary stenosis: its signs, X-ray and electrocardiogram performance, and the disease has many similarities, sometimes can cause identification difficulties. However, when the valve-type pulmonary artery stenosis, the murmur is louder, often accompanied by tremor, while the second heart sound of the pulmonary valve area is reduced or inaudible; the X-ray film shows that the lung field is clear and the lung pattern is scarce, which can be identified. Echocardiography showed an abnormality of the pulmonary valve. Right ventricular catheterization revealed a systolic pressure gradient between the right ventricle and the pulmonary artery, and evidence of no shunt was confirmed.

(D) primary pulmonary hypertension: its signs and ECG performance, and the disease is quite similar, X-ray examination can also find the total dry arc of the pulmonary artery, lung vascular shadow thickening, right ventricle and right atrium increased, However, the lung field is not congested or is clear, but can be identified. Right heart catheterization revealed evidence of a significant increase in pulmonary arterial pressure without left-to-right shunt.

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