The Telegraph
Since 1st March, 1999
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Biological pacemakers to replace electronic ones

London, Sept. 11 (Reuters): Scientists in the US have made a breakthrough that could revolutionise heart surgery by replacing electronic pacemakers with a biological equivalent.

“Our results indicate that genetically engineered pacemakers could be developed as a possible alternative to implantable electronic devices,” the researchers at Johns Hopkins University, Baltimore, wrote in Nature magazine.

The heart has natural pacemaker cells that emit an electrical impulse that prompt it to beat. If these die, they can be replaced by surgically-implanted electronic equivalents that do much the same job but have nothing like the adaptability of their biological brethren.

But the Johns Hopkins’ scientists discovered that by altering the potassium balance in ordinary heart cells in guinea pigs, they could trick them into behaving like pacemaker cells.

“We can envision a day when it will be possible to recreate an individual’s pacemaker cells or develop hybrid pacemakers — part electronic, part biologic,” said cardiologist Eduardo Marban, one of the Johns Hopkins’ team.

Likening the process to creating a hot rod car out of a junk heap, he said the scientists had tinkered with the cells’ genetic toolbox to manipulate their functions.

Warning that clinical applications in humans were still some way off, Marban said what he termed the “biopacemaker” could have vital uses in patients either too weak or too young to face implantation surgery. “A biologic pacemaker should also be able to adjust to the body’s changing needs, whereas an electronic pacemaker — at least in its simplest form — does not,” he said.

“Anything that normally makes our heart go pitter-pat doesn’t change the steady rhythm of the electronic pacemaker. Instead people get tired very quickly,” Marban added.

The heart normally has two sets of pacemaker cells that trigger their neighbours to contract and send blood round the body. Other cells are inhibited from aping these starter-motor cells by the presence of potassium.

The scientists used a virus to carry a gene that altered the potassium balance, and injected it into the guinea pigs’ hearts and quickly found the affected cells began acting as pacemakers. However, Marban warned that their understanding of the process still needed a lot of work. “We’ve created a biologic pacemaker in the guinea pig, but now the hard work comes,” he said.

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