It is usually done for one of two reasons. The first is called a “haemodynamic catheter”. This means that it is done to measure pressures and oxygen levels in the different heart chambers and blood vessels. This is information that cannot be obtained from other tests like echo scans.

The second reason is an “interventional catheter”. This is where a procedure is done via the catheter, such as putting in a stent to open up a narrowed blood vessel, using a plug to close a hole in the heart, or putting in a new heart valve.

Cardiac catheters in ACHD patients are specialised procedures because the problems that are seen in ACHD patients are different to those seen in other people.

For this reason your cardiology team will often recommend that the procedure be done in Auckland by a cardiologist who has particular training and expertise in cardiac catheterisation in ACHD patients.

For a haemodynamic catheter, most people will be able to have the procedure without a general anaesthetic. You may be given a sedative medicine to help you relax during the procedure.

Interventional cardiac catheters are a bit different and will often require a general anaesthetic. The team will discuss this with you prior to your catheter.

The procedure is carried out in a cardiac catheterisation room. This is a sterile room with specialised monitoring equipment that allows measurement of blood pressures inside the heart and X-ray imaging equipment that shows the position of the catheter as it is moved through the heart.

Thin flexible tubes called catheters are inserted into a vein or artery, usually in the groin. You’ll have a local anaesthetic injection to numb the area where the catheters are put in. These blood vessels connect up to your heart, so the catheters can be passed up into your heart.

When the catheters are inside your heart they can be used to measure blood pressures in the different heart chambers. Blood samples can be taken through the catheter to measure oxygen levels. X-ray contrast dye can be injected so that pictures can be taken of the major blood vessels coming into and out of the heart.

The picture gives you an idea of the size of an average catheter. Most of the commonly used ones are 2-3 mm in diameter. The biggest ones that are used for some interventional catheters are about 8 mm.

While a haemodynamic catheter is for finding out information, an interventional catheter is intended to fix something.

If you are having an interventional catheter the doctors will position the catheter carefully using X-ray pictures and then introduce a device through the catheter. Examples include putting in a stent to open up a narrowed blood vessel, using a plug to close a hole in the heart, or putting in a new heart valve.

The next sections talk about the types of interventions that can be performed for people with congenital heart conditions.

Stents are used to open up narrowings within blood vessels.

A stent is a small tube made of a wire mesh (a bit like a high-tech version of chicken wire). It is introduced using a special type of catheter that has a long thin balloon at its tip. The stent is positioned over the balloon and when the doctors are happy that the catheter is in the correct position, then the balloon is inflated to expand the stent. The balloon catheter is then removed and the stent stays in place.

Examples of situations where stents are used in congenital heart disease are coarctation of the aorta, pulmonary artery stenosis, and occasionally narrowings within the heart after previous surgery, for example the Mustard or Senning operations or the Fontan operation.

The picture shows a stent on a balloon catheter, before and after the balloon is inflated to expand the stent.

Click here to go to our section about coarctation of the aorta on ACHD.NZ

Click here to find out more about stenting of coarctation of the aorta from the team in Leeds, UK.

Interventional catheters can be performed to close holes between the heart chambers, like an atrial septal defect (ASD) or less commonly a ventricular septal defect (VSD). They can also be used to close extra blood vessels like a patent ductus arteriosus (PDA) or a collateral vessel.

There are a variety of devices that can be used, some as simple as a small coiled metal wire and some more complex plugs and devices that are specifically designed for closing certain types of hole in the heart.

The catheter is positioned using X-ray pictures. When the doctors are happy with the catheter position, the device is introduced through the catheter so that it blocks the abnormal hole or blood vessel. The position is then checked again before the device is released and the catheter removed.

The picture shows an atrial septal defect which has been closed using a catheter device. The device has been released and the catheter is just about to be removed.

Click here to go to our section about atrial septal defects on ACHD.NZ

Click here to find out more about ASD closure from the team in Leeds, UK.

It is now possible to implant new heart valves through a cardiac catheter. In congenital heart disease, this is most commonly done to replace a leaky or narrowed pulmonary valve, particularly in people who have had previous surgery for tetralogy of Fallot. This procedure isn’t suitable for everybody needing a pulmonary valve replacement, but for some people it can be a better option than surgery.

The catheter is positioned using X-rays and pictures are taken using X-ray contrast dye to find out more detailed information about the existing valve and some other nearby heart structures. This allows the doctors to confirm that your situation is suitable for implantation of a new valve.

The doctor then introduces the new valve through the catheter and positions it within the old valve. When the doctor is happy with the position, the valve is fixed in place using a balloon catheter and then released. The catheters are then removed and the valve stays in place.

Click here to go to our section about tetralogy of Fallot on ACHD.NZ

Click here to find out more about trans-catheter pulmonary valve replacement from the team in Leeds, UK

The risk of major complications is low, but varies a bit depending on your original heart condition and the exact procedure that you are having done. The doctor doing the catheter will talk to you about this in more detail before you give your consent to have the catheter. They will explain the potential complications of the particular procedure that you are having done.

More common complications include bleeding from the area where the catheter was put in, usually in your groin. Some people can develop a collection of blood under the skin, called a haematoma. This can be uncomfortable and will cause bruising, but should settle after a few days.

If you are taking an anticoagulant (blood-thinning) medicine you may need to stop this a few days prior to the procedure. The booking team will usually let you know, but ask if you are unsure.

On the day of the procedure you’ll usually be asked not to eat or drink anything for a few hours beforehand.

Most people will come into hospital the day before the procedure and go home the day after. So usually 2 nights in hospital, but this can vary in some cases.