Atrial septal defect (ASD) is a congenital malformation in which the septum between the right and left atria is hypoplastic leaving a defect that causes the blood flow between the left and right heart chambers to be connected. It is one of the most common lesions in congenital heart disease. Atrial septal defects are more common in women, and the ratio of female to male incidence is about 2:1.
Causes
The exact cause is still uncertain. Any factor that affects the embryonic development of the heart during the fetal heart development can cause atrial septal defect. There are three main areas.
(1) External environmental factors: the more important ones are intrauterine infections, extensive exposure to radiation, advanced maternal age, and smoking and alcohol consumption can cause atrial septal defects.
(2) Genetic factors.
(3) Nutritional factors.
Strengthening health care during pregnancy, especially early pregnancy to actively prevent rubella, influenza and other viral diseases, as well as avoiding all factors related to the onset of the disease, has a positive significance in the prevention of atrial septal defect.
Classification
According to embryology and pathological anatomy, there are two major categories, namely primary foramen ovale defect and secondary foramen ovale defect, with the latter being far more common than the former.
Clinical presentation
Primary foramen ovale defect: palpitations and shortness of breath after activity, and susceptibility to respiratory infections. In cases with severe mitral valve insufficiency, heart failure and pulmonary hypertension may appear early. The child’s development is delayed. The heart is enlarged and the precordial region is bulging.
Secondary foramen ovale septal defect: palpitations, shortness of breath and fatigue after activity are the most common symptoms. However, some children may be asymptomatic. Atrial rhythm disturbances are mostly seen in adult patients. If there is severe pulmonary hypertension causing a right-to-left shunt, cyanosis, known as Essenmenger (Eisenmenger’s syndrome), is present.
Tests for diagnosis
The best noninvasive test to confirm the diagnosis is cardiac ultrasound, which is also the best method for postoperative review. It can clarify the type, location, and size of the atrial septal defect and determine whether it can be treated with medical interventional occlusion.
Treatment
Primary foramen ovale type of atrial septal defect: This type cannot be treated with medical intervention and should be treated surgically as soon as possible after the diagnosis is established. Surgery should be performed under extracorporeal circulation to repair the septal defect with a patch.
If the child is less than 1 year old, if there are no symptoms, frequent colds and pneumonia, easy to feed, and normal growth and development, surgery may not be urgent, as there is a possibility of self-closing, and the child can be monitored by cardiac ultrasound every 3 months until 1 year old. Currently, there are two main treatment methods: medical interventional blockage and surgical open-heart repair. After surgery, the child grows normally and can engage in normal work and labor. The surgical mortality rate has been reduced to less than 1%.
Internal interventional occlusion can treat most of the atrial septal defects, except for the following cases.
(1) Primary foramen ovale type atrial septal defect.
(2) Venous sinus type septal defects.
(3) With partial or complete pulmonary vein ectopic drainage.
(4) Left intra-atrial septum (i.e., triple atrial heart).
(5) Intracardiac, inferior vena cava, or intrapelvic thrombosis.
(6) With other congenital heart defects or large vessel anomalies that require surgical treatment.
(7) Eisenmenger’s syndrome.
(8) Recent severe infection or foci of infection in the body.
Surgical open-heart repair is suitable for any type of patient, except for the following two conditions
(1) Eisenmenger’s syndrome.
(2) Severe recent infection or foci of infection in the body.
Differences between interventional occlusion and surgical repair.
Interventional occlusion can be done with only one puncture needle opening, which is less invasive, aesthetic and without scar residue after surgery, but there is a certain chance of failure, and once it fails, emergency surgery is often required, which multiplies the cost of surgery. The postoperative blocker can also have some impact on the conduction bundle and cardiac function.
Surgical repair requires an open incision in the middle of the chest, leaving a postoperative scar, but it is a “universal approach” for any type of patient. The difference in cost between the two procedures is not significant.