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April 18-26, 2006 posts
Wednesday, April 26, 2006
another article
Researchers develop a new way to assess heartbeats
Apr 21 A new light-emitting dye may reveal the inner workings of the heart's electrical system. Scientists hope this approach may shed light on the precise causes of irregular heartbeats and sudden cardiac death.
A heartbeat begins when electrical impulses are fired from the upper chambers of the heart (the atria), which contract in response to push blood into the lower chambers (the ventricles). The electrical impulses continue to the ventricles, causing them to contract and push blood to the rest of the body.
While previous research has explained much about how the heart's electrical impulses work under normal circumstances, it is still unclear what happens deep within the heart during abnormal events such as irregular heart rhythms (arrhythmias) and sudden cardiac death. Sudden cardiac death is death due to the abrupt loss of heart function, often as a result of electrical problems in the heart.
Researchers from the University of Pittsburgh hope to shed some light on the mechanics of irregular heartbeats with several newly developed types of chemical dye. These dyes make it possible to follow the electrical activity taking place several layers below the surface of the heart where cardiac contractions originate.
Visualizing the internal activity of the heart could allow researchers to better understand and protect against what happens during abnormal cardiac events.
The dyes work because of their sensitivity to changes in voltage. When the dyes are injected into the bloodstream and travel through the heart, they encounter voltage changes occurring in the membranes of heart cells. The dyes respond to the change in voltage by emitting different types of fluorescent light, depending on the level of change detected.
The fluorescent light emitted by the dye can be detected and displayed using specialized lab equipment. This allows researchers to actually see the detailed electrical changes taking place within the heart during each beat.
"What exactly causes arrhythmias and sudden cardiac death remains an important question we hope to answer through our studies that make use of a combination of novel imaging approaches. Toward this end, these dyes have proved to be particularly important for recording membrane potential changes and capturing in detail, and in real time, the synchronicity or asynchronicity of the heart," explained the study's lead author Guy Salama, Ph.D., University of Pittsburgh School of Medicine, in a recent press release.
The results of the study were published in a recent issue of the Journal of Membrane Biology.
Tuesday, April 18, 2006
This week's interesting article:
Publish Date: April 14, 2006
Girl's heart restarted after donor organ removed
Apr 14 (Reuters) - A British girl is thought to have become the first heart transplant patient in the UK and possibly the world to have had her donor organ removed and her own heart re-started, a London hospital said on Thursday.
Hannah Clark from south Wales had a heterotopic transplant operation -- known as a "piggyback" because the donor heart is placed next to the original organ -- 10 years ago.
However, complications arose after her body recently started reacting badly to the drugs she had to take to stop her body rejecting the new heart and surgeons took the decision to remove the donor organ.
"We discovered that actually her old heart was now working quite well," said a spokesman from London's Great Ormond Street Hospital for Children.
"So we removed the transplant heart, we were able to take her off the anti-rejection drugs and reconnected her old heart back up again and it worked. She's doing very well."
He added: "We would be surprised if anybody came up with another case. Maybe it's a world first."
Sir Magdi Yacoub, the Egyptian-born surgeon who performed Clark's original transplant, advised surgeons during the February 20 operation. He said he was delighted that the girl's heart had recovered so well.
"Her (original) heart recovered almost completely," he told BBC Radio. "It is now a normal heart. This is a very happy ending."
Medical experts said the operation was an important development in treating people suffering from cardiomyopathy, whereby the heart becomes inflamed and functions poorly.
"Surgeons like Magdi Yacoub have thought for some time that if a heart is failing because of acute inflammation, it might be able to recover if rested," said Professor Peter Weissberg, Medical Director of the British Heart Foundation.
"This seems to be exactly what has happened in this case. The piggyback heart allowed the patient's own heart to take a rest."
He said the modern approach to Clark's problem would be to install a temporary mechanical device, which could be removed after a few months, but that such a method had not been available 10 years ago.
"This is a great example of how a pioneering and novel approach to a medical problem can lead to surprising results that tell us a lot about how some heart diseases progress," he said.
Publish Date: April 14, 2006