This week young cardiac patients from around the world are meeting in London to celebrate the 100th non-surgical heart procedure.
A stent used to keep arteries open
The technique pioneered by Professor Philipp Bonhoeffer, who is based at Great Ormond Street Hospital for Children, involves inserting a valve into the pulmonary artery through a leg without the need to open the chest.
What type of medical conditions will
It helps children born with heart defects, particularly children born without a connection between the pulmonary artery and the right ventricle of the heart (congenital condition).
Traditionally, a number of operations are needed to fix the problem throughout their lives due to their rapid growth. The average child benefiting from this technique will have had open-heart surgery three times before.
How does the new procedure work?
A valve is put inside a stent (an ultra-thin, collapsible platinum mesh cylinder of the type commonly used to prop open weak or narrowed arteries).
The stent and valve are collapsed, then mounted on a tiny deflated balloon at the end of a catheter. The stent on the catheter can then be introduced into a blood vessel.
Once the catheter reaches the correct place the balloon is inflated and the stent expands to the required width. The balloon is then deflated, the catheter is withdrawn and the stent remains in place.
Why is the valve procedure preferred?
Traditionally, open-heart surgery has been required to correct the problem by inserting replacement valves, but this carries difficulties for patients as it normally involves opening up the chest, cutting through the sternum (breast bone) and several weeks of recovery.
Replacement valves also degrade and the original problem returns. Therefore, with open-heart surgery the valves are replaced less frequently than is clinically ideal, which can compromise the patient's quality of life.
What are the other key benefits?
The procedure is much less invasive and less traumatic to patients than open-heart surgery and recovery is also a lot quicker.
Each re-opening of the chest for surgery is progressively more difficult so it is of major benefit if this can be avoided.
The procedure also allows more timely and frequent repair of the conduit.
The heart muscle of the right ventricle is prevented from further damage. More frequent repair means the proportion of time the children spend with an inefficiently working heart is reduced. In turn, the children will be less tired, and have an increased life expectancy.
Do replacement valves need to be replaced?
Like those fitted during open-heart surgery, replacement valves inserted via catheter will not last forever.
But the hope is that, if necessary, these patients - and others like them - can receive three or four replacement valves using this method before further invasive surgery is required. This will make valve replacement dramatically less traumatic.
How long does the procedure take and what is the success rate?
On average, it takes one hour to perform and there have been no deaths linked to Professor Bonhoeffer's procedure.
Does the procedure only benefit children?
About half those treated have been children and half adults.
How many patients are benefiting from this procedure?
Once the program is rolled out worldwide experts expect that 3000 - 5000 patients will benefit from the procedure each year ('between' 200 - 300 cases in the UK each year).