Heart's Energy May One Day Power Pacemakers, Defibrillators

• by admin
• 2008-11-11 03:11:08
• General Posting
• 1981 views
• 2 comments

By Alex Nussbaum
Nov. 10 (Bloomberg) -- A beating heart's excess energy was tapped by British scientists in a first step toward extending the life of batteries that power pacemakers and other medical devices.

A generator inserted into a pig's heart on the tip of a wire produced 4.3 microjoules of electricity, about a fifth the energy needed to fuel a pacemaker and enough to help recharge its battery, researchers said in a study released at the American Heart Association's annual meeting in New Orleans.
Defibrillators and pacemakers are pager-sized devices implanted in the chest to shock faulty hearts back into rhythm. Newer versions track blood oxygen levels, temperature and other data, but advances have been limited by size and longevity of batteries, which eventually require replacement.

``Wireless technology is relatively power hungry and so there's always a balance you have to strike,'' said lead author Paul Roberts, a cardiologist at Southampton University Hospital in Hampshire, in a telephone interview. ``If you've got an additional power source, it gives you potentially more ability to communicate and to monitor the patient.''

The human heart uses only a faction of the power created by its contractions to pump blood, Roberts said. The average person's heartbeat generates 1,000 times the energy harvested in the pig experiment, he said. Pig and human hearts have similar size, shape and function.

The scientists inserted two compressible bladders and a generator on a wire threaded into the pig's heart. The bladders relayed the pressure from each beat to the generator, which converted the movements into electricity. The procedure caused ``no significant injury'' to the heart's lining, the study found.

Government Funded
The generator was designed by Zarlink Semiconductor Inc. of Ottawa and two English companies, InVivo Technology of Buckinghamshire and Southampton-based PMG Perpetuum. The British government funded the experiment.
While researchers hope to increase the amount of power produced by the heart generator, the system is unlikely to replace batteries completely, Roberts said. Siphoning too much energy would tax the heart and put patients at risk if the generator fails, he said. Instead, the organ-powered electricity is more likely to serve as a permanent recharger for a pacemaker or defibrillator, perhaps extending its life indefinitely.

Devices implanted elsewhere in the body may someday generate power from muscle movements or other sources, Roberts predicted.

Limited Life
Batteries usually last five years in defibrillators and up to seven in pacemakers, after which patients need surgical replacements. While plugging into the heart may change that, it's likely to take a decade of research and engineering before the technology is widely available, said Mark Estes, president of the Heart Rhythm Society, a Washington, D.C., group representing doctors who treat irregular heartbeats.
``It's the first step of a journey,'' Estes, who was not involved in the study, said in a phone interview. ``There's miles and miles from a device in a single pig to something that has a clinical impact.''

To contact the reporter on this story: Alex Nussbaum in New York anussbaum1@bloomberg.net.