The arterial duct (patent ductus arteriosus, or PDA) is a short blood vessel connecting the two main arteries which come off the heart to feed the lungs and the body with blood. It is a normal part of the circulation before birth and normally closes by itself within the first week or so after birth. Sometimes the duct fails to close by itself. This results in the lungs becoming congested because they receive too much blood. This may cause only mild symptoms in young children (such as breathlessness) but if a duct is left untreated over a period of many years it may eventually lead to permanent damage to the heart and the lungs. This may prove fatal when the patient reaches later adult life, so it is important that large ducts are treated when the patient is young and before the heart or lungs have been permanently damaged. If the duct is small there is very rarely any risk of damage to the heart or lungs, but there is a risk of serious infection occurring inside the duct later in life. For that reason we recommend that even small ducts should be closed.
"Keyhole" treatment for PDA
Most ducts are small (only a couple of millimetres or so in diameter) and can be safely closed without opening the chest by placing one or more small stainless steel coils in the duct, inserted through a small tube (catheter) in the vein or artery at the top of the leg, using X-rays to guide it into position. This is the standard treatment for small ducts nowadays. The procedure is usually performed under general anaesthetic; the patient is usually in hospital for only one or two nights and returns to full normal activities within a day or so after the procedure. A newer device, the Amplatz plug, made of a mixture of very fine wire (Nitinol) and synthetic cloth (Dacron), is available for closing larger ducts. It is put in to the duct in a very similar way to a coil. Once in the correct position inside the duct, the coil or plug is unfolded by pushing it out of the catheter. It is held inside the duct by its specially designed shape and once in position it is released and stays inside the duct, permanently blocking it (although complete closure sometimes doesn’t always occur immediately after the device is implanted). The device stays inside the duct and becomes covered over by the patients own tissue during the healing process. It is worth remembering that a coil or plug will be visible on a chest X-ray for the rest of the patient’s life. No special treatment is required after coil or plug closure of the duct but for a period of one year afterwards a single dose of antibiotics is given before dental extractions or scalings to avoid bacteria getting into the blood from the mouth causing infection on the device.
Closure with Amplatz Plug
What could go wrong?
Occasionally when we try to close the duct none surgically the duct proves to be too big. If that happens surgery will be necessary, but it is not usually possible to arrange that immediately, so the patient is sent home and arrangements are made for the operation to be done later. Rarely, after the device in placed in the duct it may move out of position; when this happens with a coil it is not usually serious and it is usually possible to "fish it out" again and to put a larger coil in, but if the Amplatz plug moves out of position surgery may be necessary to retrieve the plug (either to remove it from the artery at the top of the leg or from the artery in the lungs). There is also a risk of infection occurring on the coil or plug; this is very rare but is a serious complication and would almost certainly require surgery to remove the device. There is a small chance that the device will not quite completely close the duct; if there is only a very small duct left it can heal up on its own without treatment, but if it doesn’t we usually recommend a repeat procedure one or two years later. In about 1 in 50 cases where coils are used and there is a small residual duct, the jet of blood past the metal device causes damage to the blood cells (this causes the urine to be very dark and the patient to become anaemic); in these cases it may be necessary to repeat the procedure to block the duct completely. Because the Amplatz plug is still fairly new, we do not know exactly what the risk of complications using this device is, but evidence shows that the risk to the patients life is extremely small whatever device is used. It is, however, important that you understand that there is a very small risk to the patient’s life whether the duct is closed with an operation or with keyhole treatment. These very small risks of treatment have to be balanced against the potentially serious risk to the patient’s life if the duct is left untreated.
Surgical treatment may still be required for some large ducts. This involves opening the side of the patient’s chest, leaving a scar, although this usually heals well and is often barely noticeable later in life. Operations to close ducts are usually straightforward but require 5 or 6 days in hospital to recover compared to the one or two days in hospital for non surgical treatment. There is a small risk even with surgery that the duct may not be completely closed, and in such cases the small residual duct can almost always be closed safely without further surgery, using keyhole treatment at a later date. There is always a very small risk with any kind of heart operation. The risk of dying at operation is extremely small (probably around one in a thousand), but complications such as fluid collecting around the lungs or the heart after surgery may sometimes occur. These are very rarely serious but can prolong the stay in hospital. Most patients are completely back to normal activities within 4 weeks after the operation.
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.