Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


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


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:

More articles from Health and Medicine:

nachricht Resolving the mystery of preeclampsia
21.10.2016 | Universitätsklinikum Magdeburg

nachricht New potential cancer treatment using microwaves to target deep tumors
12.10.2016 | University of Texas at Arlington

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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>