Atrial septal defect (known as ASD) is a hole between the two small chambers of the heart. It allows blood from the left sided chamber to pass to the right sided chamber. This results in the right side of the heart being overloaded with blood and also results in the lungs becoming congested because they receive an excessive amount of blood. Such defects cause only mild symptoms in young children (such as breathlessness on exertion), but if an ASD is left untreated over a period of many years it eventually leads to permanent damage to the heart and sometimes to the lungs as well. This may prove fatal when the patient reaches later adult life, so it is very important that ASD is treated when the patient is young and before the heart or lungs have been permanently damaged.
Surgical treatment for ASD
The usual treatment for ASD is an operation on the heart to close the hole. This involves opening the patient’s chest and taking over the function of the heart and the lungs with a machine whilst the heart is stopped and opened to allow the surgeon to repair the hole. There is a scar on the front of the chest after the operation. Operations to close ASDs are usually straightforward these days - although there is a very small risk (about 1 in 300) of dying at surgery. There is also a very small risk with heart operations that blood clots or pockets of air might form in the heart; these may very rarely be serious enough to cause brain damage. There are other minor risks involved, such as fluid collecting around the lungs or the heart after surgery, but these are also very rarely serious. The operation takes about 3 hours and usually involves a stay in hospital of about 1 week. Most children are completely back to normal activities within 6 weeks after the operation although adults take a little longer to recover fully.
"Keyhole" treatment for ASD
The Amplatz button is a fairly new device for closing ASDs without opening the chest. It is made of a mixture of very fine wire and synthetic cloth (Dacron). It is delivered to the heart folded up inside a long thin tube (catheter) which is inserted into the vein in the groin under general anaesthetic. Once in the correct position, the device is unfolded by pushing it out of the catheter. It is held inside the ASD by its "button" shape and once its position is satisfactory it is released and stays inside the heart, permanently blocking the hole. It has been used safely and effectively in animals and in patients, although the number of patients is still fairly small (about 25,000 up till June 2002). The device stays inside the heart and becomes covered over by the patients own tissue during the healing process. Potential advantages of this new type of treatment are that it can avoid the discomfort of an operation, can avoid a scar on the chest, can avoid some of the complications of surgery such as fluid collecting in the chest, and can shorten hospital stay to only one or two nights in hospital. Experience so far suggests that only about half of all ASDs are suitable for this type of closure, because the hole needs to be more or less in the middle of the atrial septum (the partition between the two small chambers) for successful closure.
Patients who are not suitable will require surgical treatment, as they have in the past. We usually have a good idea which patients might be suitable after a straightforward ultrasound scan of the heart (an echocardiogram), but we can only be certain that a particular patient is suitable by performing a more complicated scan called a transoesophageal echo (or TOE). This is done under the same anaesthetic as the procedure itself, and involves passing a tube down the patient’s throat so that really clear echo pictures can be taken from immediately behind the heart. The TOE also helps, along with X-ray pictures, to position the device. The procedure takes approximately one and a half hours and the patient is usually sent home the day after. Progress will be checked at outpatient visits (just as after an operation).
What could go wrong?
One of the biggest difficulties in trying new procedures is that we don’t have enough experience to know exactly what could go wrong and we will not know this, or whether this treatment is better than surgery, for many years yet (until many thousands of patients have been treated). Devices like this are carefully tested before they are used in humans, and we know from the device being used in animals and in about 4000 humans that it appears to be safe and effective. Nonetheless, it is possible that complications might occur. Possibilities are: the device not staying in place after insertion (this would require an operation to retrieve the device and close the hole at the same time); a residual hole might be left, and if large this might need surgical treatment; blood clots forming inside the heart during the procedure; and infection of the device (this would also require it to be removed at operation). Of all these risks, blood clots are the most serious as there is a chance they might cause a stroke (brain damage) or even cause death. We do not know exactly what the risk of such complications is, but studies so far suggest that the risk is probably less than for surgical closure of the hole. It is, however, important that you understand that there is a very small risk to the patient’s life and a very small risk of brain damage whether the ASD is closed with an operation or with the new device. These very small risks of treatment have to be balanced against the risk to the patient’s life if the ASD is left untreated.
Headaches after ASD closure
Some patients who have suffered from migraine in the past find that their migraine is worse for a few months after keyhole closure of their ASD, and some patients find their migraine disappears after keyhole treatment. The reasons for a change in pattern of migraine are not fully understood.
General advice for the future
Most patients will remain completely well and lead a completely normal life after treatment to close an ASD. No restrictions to physical activity are recommended and no special precautions are necessary.
How to interpret the survival funnel plots
These graphs show the national average survival after specific procedures for treating congenital heart disease. The national average is shown as a horizontal grey line. Two control limits are shown; a warning limit (Green line, 98%) and an alert limit ( Red line 99.5%). Unit performances are shown as identifiable coloured symbols. If a unit's symbol is above the green line then the performance is no different from the national average. If a unit’s survival rate is below the warning limit, their performance will be closely monitored in subsequent years. If a unit’s survival rate is below the alert limit, an investigation into possible reasons and remedial actions will be launched by the appropriate professional and regulatory bodies.