Atrial septal defect (ASD) occurs due to congenital heart disease where the septum split the left and right atria fails to close completely so that communication between the two occurs. ASD incidence rates range from 10% to 25%.
Defects in the atrial septum will cause blood mixing from the systemic circulation and pulmonary circulation. If defects are not corrected, there can be an overload of right heart volume, atrial arrhythmia, and pulmonary arterial hypertension. There are 3 types of major atrial septal defects, namely the ostium secundum defects, ostium primum defects, and sinus venosus.
ASD shunts are generally detected during childhood or young adulthood. Defects can sometimes be tolerated in infants and young people, although symptoms such as fatigue, growth disorders, and tightness when activity can occur. The findings of the physical examination can be either a pulmonary midsystolic murmur or an ejection murmur, followed by a fixed split heart sound. A supporting examination to establish a diagnosis of ASD is echocardiography.
Small ASDs may close spontaneously without surgery. Meanwhile, large defects can be persistent and lead to hemodynamic sequels and clinics that require retrofitting interventions or open surgery. Please note that the presence of severe pulmonary arterial hypertension is contraindicated defect closure. [1-3]
Atrial Septal Defect Definition
Atrial septal defect (ASD) is a condition when there is a hole in the heart wall (septum) that separates among the two upper heart chambers (left and right atrium). ASD is one of the congenital heart defects. That is, this disorder has been around since a baby was born.
Under normal conditions, blood in the right heart chamber flows to the lungs to take in oxygen. Then, blood rich in oxygen returns to the heart through the left heart chamber. In this heart part on the left side, oxygenated blood will be pumped throughout the body.
However, in people with ASD, oxygenated blood on the left can leak and mix with the blood on the right. As a result, the blood that will flow to the lungs increases, which can also increase the lungs pressure (pulmonary hypertension). Therefore, this condition is often called a heart chambers leaking.
Atrial Septal Defect Causes
The presence of a hole in the heart atrium wall is actually a normal condition, if it occurs in the fetus. This hole serves to change blood flow, so that blood comes out of the lungs.
It’s just that, when the baby is born, the hole is no longer needed. So, under normal conditions, it will close by itself, within a few weeks or a few months after birth.
In children with ASD conditions, the hole does not close itself or the hole is larger than it should be. This makes blood flow in the heart becomes disrupted.
Under normal conditions, the heart left part will only pump blood from the heart to all over the body and the heart right part pumps blood to the lungs. In children with ASD, blood that should flow on the heart left side, it can change the direction of the flow to the heart right side and mix, then to the lungs.
If the hole is large enough, then excess flow of blood to the lungs will make the heart work and lungs become heavier. Over time, this condition can damage both vital organs.
Atrial Septal Defect Clinical Features / Symptoms
Most babies have no clinical complaints or are called asymptomatic in ASD. ASD abnormalities are generally known through routine examinations where murmurs are found. If there are symptoms or complaints, there should be tightness during activities, fatigue, and recurrent respiratory infections. The most common complaint in older persons is decreased stamina and palpitations (chest palpitations) resulting from an enlarged right atrium.
- Vick G, Bezold L. Isolated atrial septal defects in children: classification, clinical features, and diagnosis. UpToDate, 2021. https://www.uptodate.com/contents/isolated-atrial-septal-defects-asds-in-children-classification-clinical-features-and-diagnosis
- Menillo AM, Lee LS, Pearson-Shaver AL. Atrial Septal Defect. [Updated 2021 Aug 11]. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK535440/
- Adler D. Atrial Septal Defect. Medscape. 2021. https://emedicine.medscape.com/article/162914-overview