There are four chambers in the human heart. The upper two are called atria. The atrial septum separates the atria into right and left chambers. The right atrium receives blood from the veins of the body, and the left atrium receives blood from the lungs. Before birth, there is normally an opening in the atrial septum that allows blood to bypass the lungs. The opening is supposed to close at about the time of birth, but remains open in about 1 out of 1,000 babies.The size of the defect can be very small or more than an inch in diameter. The higher blood pressure in the left atrium pushes blood into the right atrium, adding to the normal supply coming from the body to the heart. This added volume increases both the workload of the right ventricle (the pumping chamber to the lungs) and the flow of blood in the lungs.
How does it occur?
As you may imagine, a baby’s development from a tiny egg requires very complex changes. Just what goes wrong is unknown. A gene defect or other influences may prevent the heart tissues from developing properly. An atrial septal defect usually does not otherwise prevent the heart or the baby from developing normally, and the defect does not appear to be inherited.
What are the symptoms?
Unless the defect is very large or associated with some other cardiac defect, most babies and children have few or no symptoms. In fact, many people may live their entire lives with small atrial septal defects and are unaware of it. Some people will not develop symptoms but may need surgery when they are middle-aged. Larger defects may cause symptoms including shortness of breath, sweating a lot with activity, increased breathing rate, or decreased growth. The extra blood flow through the lungs may cause an increase in blood pressure in the lungs. Congestive heart failure may develop, with cough and swelling of the legs or ankles. Occasionally, the added strain on the heart results in irregular heart rhythms.
How is it diagnosed?
If the defect is small, diagnosis is difficult and a heart echocardiogram may be the only clue to its presence. A heart echocardiogram bounces sound waves off the heart to create a detailed picture of the heart and its structures. This is a painless procedure that can be done in your doctor’s office.
Increased blood pressure in the lungs can also be detected by the heart echocardiogram. Increased blood pressure in the lungs is sometimes measured by placing a small tube in the lung arteries.
In larger defects there is an increased flow of blood through the heart that creates a heart murmur, which can be heard with a stethoscope. The increased blood flow may also cause heart enlargement noted on a chest x-ray or on an electrocardiogram. An electrocardiogram is a test that measures the electrical activity of your heart.
How is it treated?
Not all septal defects need treatment. Some are so small they never cause problems. Children who develop symptoms as a result of the defect should have surgery to close the hole. This helps prevent the development of high blood pressure in the lungs.
The surgeon may patch the defect using a small piece of tissue from the sac surrounding the heart (the pericardium). If the hole is small enough, the surgeon may sew it shut. Sometimes the defect can be fixed by pushing a flexible plastic “umbrella” through a leg vein and attaching it over the hole. This form of treatment does not require chest surgery.
For adults, the situation is not quite so clear. In most reports, adults with symptoms who were treated with surgery did better than those not treated. However, those with high blood pressure in the lungs are not good candidates for surgery because of the poor results. Adults with mild symptoms may do as well with nonsurgical treatment as with surgery. Your doctor will make a recommendation based on the extent of the disease and your symptoms.
When should I call the doctor?
If you have a known atrial septal defect and no symptoms, try to live as normally as possible. Call your doctor if you notice a sudden increase in shortness of breath, you awake at night short of breath, or you become aware of an irregular heartbeat. Regular checkups are recommended.