How does septal defect shunt?

Written by Tang Li
Cardiology
Updated on September 03, 2024
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Atrial septal defect is the most common congenital heart disease in adults, accounting for 20%-30% of all adult congenital heart conditions. The impact of an atrial septal defect on hemodynamics primarily depends on the amount of shunting. Due to higher pressure in the left atrium compared to the right atrium, a left-to-right shunt is formed. The amount of shunting depends on the size of the defect, as well as the compliance of the left and right ventricles and the relative resistance in the systemic and pulmonary circulations. Diseases that affect the compliance of the left ventricle, such as hypertension and coronary artery disease, can increase the extent of the left-to-right shunt. A continuous increase in pulmonary blood flow leads to pulmonary congestion, increasing the load on the right heart. Pulmonary vascular compliance decreases, progressing from functional pulmonary arterial hypertension to organic pulmonary arterial hypertension. As right heart system pressure continuously increases and eventually exceeds the pressure in the left heart system, the original left-to-right shunt reverses to become a right-to-left shunt, resulting in cyanosis.

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Written by Tang Li
Cardiology
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Can atrial septal defect be cured?

Atrial septal defect is a common congenital heart disease. When the defect is small, some patients may heal naturally. In recent years, with the development of interventional technology for congenital heart diseases, most patients with atrial septal defects can be completely cured through interventional treatment, and some through surgical treatment. However, some patients have a large atrial septal defect with significant left-to-right shunting, leading to severe pulmonary arterial hypertension and right heart failure, which generally results in a poor prognosis. Some patients also have complications such as atrial flutter and atrial fibrillation. Certain patients may experience right heart failure due to excessive load on the right ventricle, and these patients often have a poor prognosis.

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Written by Tang Li
Cardiology
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Can someone with an atrial septal defect get pregnant?

Whether patients with atrial septal defects can become pregnant depends on the following factors: 1. Whether the patient normally has symptoms. 2. Whether the echocardiography indicates heart enlargement or pulmonary hypertension. 3. The size of the atrial septal defect. 4. Whether there is a combination of arrhythmias such as atrial flutter or atrial fibrillation, and complications such as pulmonary hypertension or heart failure. For those without symptoms, and where the defect does not cause pulmonary hypertension or right heart enlargement, choosing to become pregnant is possible. Complications are not common in pregnant women with isolated atrial septal defects without pulmonary hypertension. Studies have shown that the incidence of complications in pregnant women, whether the defect is repaired or not, is relatively low. If the patient has related arrhythmias and complications, it should be closely monitored, because the cardiovascular system of the mother undergoes changes during pregnancy, leading to increased cardiac workload and a higher burden on the heart, which in turn can increase the incidence of arrhythmias. For women who are already at high risk of atrial flutter or fibrillation, this risk can increase further. Additionally, pregnant women are in an older physiological state, making it easier to form blood clots, and for those with atrial septal defects, the risk of paradoxical thrombosis increases.

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Written by Tang Li
Cardiology
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Do infant atrial septal defects heal by themselves?

Atrial septal defect is a common congenital heart disease, accounting for about 1/1500 of newborns, and is most commonly found in infants and children. The impact of atrial septal defects on hemodynamics mainly depends on the amount of shunting. Some studies confirm that atrial septal defects smaller than six millimeters can close on their own without external intervention. Therefore, when an atrial septal defect is discovered, it is necessary to regularly recheck the cardiac echocardiography to determine the size of the defect. If the atrial septal defect decreases in size as the patient ages, there is a possibility of self-healing. If the area of the patient's atrial septal defect does not change or gradually increases, regular echocardiography rechecks are needed, and cardiac catheterization may be performed if necessary.

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Written by Li Hai Wen
Cardiology
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How severe is an atrial septal defect considered to be?

Atrial septal defect (ASD) is a relatively common congenital heart disease in clinical practice. From a medical perspective, the severity of ASD depends on whether the patient is an adult or a child. For adults with ASD, generally speaking, defects larger than 20 millimeters are considered large atrial septal defects, which are more severe. If the defect size is between 10 and 20 millimeters, it is often classified as a moderate atrial septal defect. Defects smaller than 4 millimeters are considered small atrial septal defects. Generally, small and moderate atrial septal defects are not severe. For children, an atrial septal defect larger than 10 millimeters is considered a large atrial septal defect, which is more severe. Sizes between 5 and 10 millimeters are classified as moderate atrial septal defects. Defects smaller than 5 millimeters are considered small atrial septal defects, which generally are not severe.

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Written by Li Hai Wen
Cardiology
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Can atrial septal defect heal by itself?

Atrial septal defect is a relatively common congenital heart disease in infants and toddlers. It is indeed possible for a child's atrial septal defect to close on its own. Some atrial septal defects can close as the child grows. Depending on the severity, atrial septal defects can be categorized into small defects. Generally, if the defect is less than 5 millimeters, it is possible for the defect to close as the child develops. If it has not closed by the age of two, it generally will not close on its own thereafter.