Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Little-studied waves in the heart may be cause of defibrillation failure

09.12.2003


Vanderbilt University researchers believe a slow electrochemical wave, known as a damped wave, may be one of the reasons that low-voltage defibrillation shocks fail to halt fibrillation in cardiac patients.



The findings by Vanderbilt University researchers John Wikswo, Veniamin Sidorov, Rubin Aliev, Marcella Woods, Franz Baudenbacher and Petra Baudenbacher were published in the Nov. 14 issue of Physical Review Letters.

Fibrillation is a series of rapid, disorganized contractions in the heart caused by multiple uncoordinated, self-generated electrochemical waves that prevent the heart from pumping blood, quickly causing death.


"In normal conditions, an electrochemical wave moves smoothly across the heart, like expanding ripples in a lake when you toss in a stone. This wave then triggers a smooth and orderly contraction of the muscle," Wikswo, the Gordon A. Cain University Professor and Director of the Vanderbilt Institute for Integrative Biosystems Research and Education, said. "In fibrillation, it is as if someone continually throws in lots of rocks at different spots in the lake. In the resulting confusion, no blood gets pumped."

The application of a strong electrical shock, either with paddles on the chest or with an implantable defibrillator, is the best way to stop fibrillation. Ideally, a defibrillation shock would stop all waves in the heart and prevent new waves from arising spontaneously.

"You want to use as low a voltage shock as possible to minimize tissue damage and, for implantable defibrillators, to save your batteries," Wikswo continued. "However, if the voltage is too low, fibrillation returns immediately and you have to try again. The puzzle is why."

Wikswo’s study explores the possibility that some waves might not be fully extinguished by a low voltage defibrillation shock, or new waves might be created by the shock, causing defibrillation to fail. If these remaining or new waves were the difficult-to-detect damped propagating waves, they could propagate slowly within the heart wall, rather than slowly dying out as previously expected. This might cause the heart to return to fibrillation or another cardiac arrhythmia.

"Damped propagating waves are not generally well understood, largely because they are difficult to view and to study," Wikswo said. "It turns out cardiac tissue provides a beautiful example of these waves."

Although cardiac graded responses have been considered for some time, recent advances in high-speed imaging, data processing and numerical modeling are just now allowing their quantitative analysis as damped, propagating waves.

To study the damped waves, Wikswo’s team initiated a wave with a strong stimulus that moved smoothly across the heart. They then created a damped wave with a weaker stimulus and sent it in the wake of the first.

"If you timed it just right you could find that the second wave would hesitate and then split in two," Wikswo continued. "One half would get smaller and slowly die, while the other half would sharply increase and eventually become a self-continuing wave on its own."

This second, self-continuing wave could be a cause of defibrillation failure.

"What surprised us is the ease with which we could create damped waves that hung around for 50 milliseconds, which is a long time when you are defibrillating the heart," Wikswo said.

The research, conducted by studying the rabbit heart, lays the foundation for future studies to determine if the waves created under experimental conditions also occur spontaneously following defibrillation.

Future studies based on this research will be conducted to better understand how to manage these waves, the effect of anti-arrhythmic drugs on them, and whether these findings could be used to improve the efficiency of cardiac defibrillators.

Melanie Catania | Vanderbilt University
Further information:
http://sitemason.vanderbilt.edu/newspub/bjfTyg?id=8580
http://www.vanderbilt.edu/lsp/abstracts/1501-Sidorov-PRL-2003.htm

More articles from Health and Medicine:

nachricht 'Exciting' discovery on path to develop new type of vaccine to treat global viruses
18.09.2017 | University of Southampton

nachricht A new approach to high insulin levels
18.09.2017 | Schweizerischer Nationalfonds SNF

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

Im Focus: Artificial Enzymes for Hydrogen Conversion

Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.

Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

New quantum phenomena in graphene superlattices

19.09.2017 | Physics and Astronomy

A simple additive to improve film quality

19.09.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>