Saturday, January 9, 2010

MRI Heart Operation; Turning Wood Into Bone

Jack Walborn, a British six-year-old boy, has become the first person in the world to have a heart valve widened using an MRI scan for guidance rather than X-ray imaging. He was born with the heart condition pulmonary valve stenosis, which reduces blood flow to the lungs.

Using MRI means patients are not exposed to radiation - particularly important for children. The scan also provides a clearer image, and information about the body's tissues, in real time during surgery.

Jack's condition meant that the flow of blood from the right side of his heart was obstructed.

Surgeons decided he needed an operation called a valvuloplasty to widen the valve and increase blood flow. This is done by inserting a catheter into a blood vessel in the arm or groin and guiding it to the heart. At the tip of the catheter is a balloon which is gently inflated to widen the narrowed valve.

X-ray imaging is usually used to track the progress of the catheter through the body.

But a team at the King's Health Partners Academic Health Sciences Centre in London has developed a way to use MRI scanning instead.

Previously, the magnetic field used in MRI caused problems with the metal guide wires used for cardiac catheterization, making them move around inside the body and heating them up. The King's team have come up with a glass fiber wire alternative with small iron markers along it that can be seen on the scan.

Scientists in Italy have developed a way of turning rattan wood into bone that is almost identical to the human tissue. At the Istec Laboratory of Bioceramics in Faenza near Bologna, a herd of sheep have already been implanted with the bones.

The process starts by cutting the long tubular rattan wood up into manageable pieces. It is then snipped into even smaller chunks, ready for the complex chemical process to begin. The pieces are put in a furnace and heated. In simple terms, carbon and calcium are added. The wood is then further heated under intense pressure in another oven-like machine and a phosphate solution is introduced.

After around 10 days, the rattan wood has been transformed into the bone-like material.

"It's proving very promising. This new bone material is strong, so it can take heavy loads that bodies will put on it. It is also durable, so, unlike existing bone substitutes, it won't need replacing." -Dr. Anna Tampieri

Several types of wood were tested before they found rattan works best. That is because of its structure and porous properties, which enable blood, nerves and other compounds to travel through it.

Dr. Tampieri says it is the closest scientists have ever come to replicating the human bone because, she says: "It eventually fuses with real bone, so in time, you don't even see the join."

The new bone-from-wood program is being funded by the European Union.

Implants into humans are about five years away. With no signs of rejection or infection in the sheep, there is real hope here that a natural, cheap and effective replacement for bones is now possible.

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