Researchers propose a new method for interrupting spiral waves that use less energy and may be less painful than traditional defibrillation.
|Example of fibrillation (multiple spiral waves) being terminated instantly by a designed stimulus that teleports all spiral wave pairs to annihilation. Georgia Institute of Technology|
A spiral wave of electrical activity in the heart has the potential to be fatal. A single spiral wave causes tachycardia (excessive heart rate), and multiple spirals cause fibrillation (disorganized contraction). Georgia Institute of Technology researchers propose a new method for disrupting spiral waves that uses less energy and may be less painful than traditional defibrillation.
This study is being conducted in the lab of School of Physics Professor Flavio Fenton, his student Noah DeTal, and research scientist Abouzar Kaboudian. Their latest findings are published in the journal Proceedings of the National Academy of Science in the paper "Terminating Spiral Waves with a Single Designed Stimulus: Teleportation as the Mechanism for Defibrillation."
The Problem with Spiral Waves
The heart contracts and sends blood throughout the body thanks to electrical waves. When a wave transforms into a spiral, its rotation is faster than the heart's natural pacemaker, suppressing normal cardiac function. Instead, one spiral wave can spawn more spirals until the heart is engulfed by multiple spiral waves, causing disorganized contraction and preventing the heart from supplying blood to the body.
Scientists and doctors have been working for years to find the best way to stop spiral waves before they become uncontrollable. Nonetheless, for more than a half-century, the best method has been a single strong electric shock. The 300 joules of energy required for defibrillation excite not only the heart cells but the entire body, making the procedure extremely painful for the patient.
The Symmetrical Solution
Because spiral waves form in pairs, they must also end in pairs, according to the researchers. Every spiral wave is linked to another spiral that is moving in the opposite direction. Combining the spiral waves with an electric shock instantly eliminates both waves.
To target spiral waves, the researchers used a mathematical method to identify key regions for electrical shock stimulation. They discovered that delivering a stimulus to the tissue areas where a spiral wave had just left and being able to sustain a new wave could defibrillate the heart.
According to the researchers, because spiral waves form in pairs, they must also end in pairs. Each spiral wave is connected to another spiral moving in the opposite direction. When spiral waves are combined with an electric shock, both waves are instantly eliminated.
The researchers used a mathematical method to identify key regions for electrical shock stimulation in order to target spiral waves. They discovered that defibrillating the heart could be accomplished by delivering a stimulus to the tissue areas where a spiral wave had just left and being able to sustain a new wave.
The researchers intend to test this concept further using two-dimensional cultures of heart cells.
"The next step is to demonstrate experimentally that what we did numerically is feasible," Fenton explained.
Eventually, Fenton added, they hope to develop methods that can be used in clinical settings, and they are working with cardiologists at Emory University on this.
Reference: DOI: 10.1073/pnas.2117568119