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Diagnostic and interventional cardiac catheterisation
Cardiac catheterisation is a minimally invasive way of acquiring information about the heart and circulation. Fine flexible tubes (cardiac catheters) are passed into the vessels and heart under x-ray guidance. The catheters are usually placed from the vessels at the top of the groin although the vessels in the neck, arm and liver may also be used. In children and infants the procedure is carried out under general anaesthetic and can be carried out under local anaesthetic in older children and adults. Information about the circulation is obtained by measuring the pressure and oxygen saturations at various points in the circulation. X-ray pictures of the heart and vessels can also be undertaken by injecting contrast (a type of dye that can been seen on x-ray) a process known as angiography. Two to three decades ago this process of diagnostic cardiac catheterisation was used commonly to work out the precise problem even in relatively straightforward congenital heart disease. Advances in other imaging techniques, in particular echocardiography, CT scanning and MRI has allowed the majority of congenital heart disease to be diagnosed without a cardiac catheter. However diagnostic cardiac catheters continue to be vital in providing additional information particularly when accurate pressure information is required to plan management and for complex cases.
Over the same period of time there have been huge advances in therapies which can be delivered via cardiac catheter- interventional cardiac catheterisation. In some cases this is as a less invasive direct alternative to open heart surgery and in others procedures are carried out in patients who are too high risk for surgery or in whom there is no surgical option. Commonly carried out procedures include passing a balloon over a wire across a narrow valve or vessel and then inflating the balloon to relieve the narrowing (balloon valvuloplasty/ angioplasty), opening up a narrowed vessel with a stent mounted on a balloon and deploying devices passed through the catheters across holes in the heart or abnormal vessels to seal them off. More recently certain valve replacements (in particularly the pulmonary valve) can be carried out interventionally in the catheter lab by passing a folded valve mounted on a stent to the appropriate position and inflating it there.
Interventional and diagnostic congenital cardiac catheters in the UK are carried out by interventional congenital cardiologists and all centres carrying out surgery for congenital heart disease (by definition) also carry out cardiac catheters. There is a close interplay between interventional cardiologists and congenital cardiac surgeons as part of the wider team to work out the optimum therapeutic plan for the patient. In certain situations, the approach to the heart is more safely achieved directly by the surgeon with the interventional cardiologist carrying out the procedure through access placed directly into the heart or main vessels. These are known as hybrid procedures.
Audit and risk
In general, interventional catheter procedures are safe with a significant complication rate from routine procedures (which make up the majority of cases) of much less than 1%. However certain subgroups of patients represent a much higher risk both as a result of the underlying diagnosis and other factors including the existence of other medical problems and the babies size. The possibility and risk of these complications is discussed with patients/ parents prior to the procedure. All units carry out regular local audit of interventional cases and all units submit survival outcomes of every case to the national database (NICOR). This ensures that each units outcomes are comparable to other UK units and allows early identification of any potential problems. It is well recognised that the UKs outcomes from congenital interventional procedures are among the best in the world.
Congenital interventional paediatric cardiologists undergo at least five years specialist training in congenital cardiology. The first three of these cover all aspects of congenital cardiology including with regular exposure to catheter procedures. During the other two years the trainee will sub-specialise in cardiac catheterisation and build up experience towards becoming an independent operator. All units carrying out catheter procedure offer this training and trainees often spend a year of this training (or an additional year) at another UK unit or abroad. Following ascertainment of certificate of completion of training (CCT) some units offer a post CCT fellowship allowing an additional year's training. Once appointed as a consultant there is an ongoing process of continued medical education (CME) which includes regular discussion with operators from other units and device specific training and proctoring when new procedures, techniques and devices become available.
Additional information/ Links
[Content provided by Dr David Crossland, Consultant Paediatric Cardiologist, Freeman Hospital - Last updated 12 September 2016]
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