In groundbreaking research published in Chaos, scientists from Sergio Arboleda University in Colombia and the Georgia Institute of Technology have explored a novel approach to defibrillation that could dramatically reduce the energy needed to reset irregular heart rhythms. Using an electrophysiological computer model of the heart’s electrical circuits, the research team discovered that the mechanism behind ultra-low-energy defibrillation doesn’t rely on traditional methods of wave synchronization. Instead, the technique involves strategically timed electric fields that prevent errant waves from propagating through heart tissue, ultimately stopping arrhythmias with much less energy than current defibrillation methods require.
Roman Grigoriev, one of the study’s authors, noted that the results were surprising. “The mechanism for ultra-low-energy defibrillation isn’t about synchronizing the excitation waves, as previously thought. It’s actually about blocking waves from spreading through parts of the heart tissue that haven’t fully recovered from a prior excitation.”
Traditional defibrillation devices, while effective, can be painful for patients and often cause damage to the heart tissue due to the high energy involved. Implantable defibrillators, which deliver electric shocks directly to the heart, pose particular challenges. They require a significant amount of power to function and carry health risks from frequent replacement surgeries, which are necessary due to battery depletion.
The study’s authors used an adjoint optimization method to address these issues. This technique involves adjusting the electric field applied over an extended period, allowing them to fine-tune the voltage so that it stops abnormal heart activity with the minimum possible energy. The optimization method works by solving the heart’s electrophysiologic model for a given input and then “rewinding” through time to adjust the voltage profile based on where the electrical field needs to be modified to achieve defibrillation.
Unlike conventional defibrillation, which applies a single high-energy shock to reset the heart’s rhythm, the new method uses a more nuanced approach. By incrementally varying the electric field over time, the researchers were able to explore the “vulnerable window” in the tissue. During this window, heart tissue is more susceptible to small disturbances that can prevent the wave of excitation from continuing its abnormal path through the heart, a concept central to their low-energy defibrillation strategy.
In a healthy heart rhythm, electrochemical waves initiated by pacemaker cells in the upper heart chambers, or atria, move through the heart in a synchronized manner, resulting in coordinated contractions. However, in arrhythmias like fibrillation, the waves become chaotic, rotating instead of propagating normally, which disrupts the rhythm and prevents efficient heart function. The “vulnerable window” refers to a delicate timing interval where a wave may or may not propagate based on slight changes in timing or minor external influences.
Grigoriev emphasized the unique approach taken in this study: “Our mechanism for ultra-low-energy defibrillation leverages the heart tissue’s heightened sensitivity during the vulnerable window. By carefully varying the electrical field over a longer time period, we can effectively block the rotating waves in the heart tissue’s sensitive regions, restoring normal rhythm without a single intense shock.”
This work suggests a future where defibrillation could be achieved with minimal discomfort and damage, a breakthrough with significant implications for patients with arrhythmias who rely on implantable cardioverter-defibrillators (ICDs). Lowering the energy required for defibrillation would reduce tissue damage and could extend the battery life of ICDs, reducing the frequency of replacement surgeries. These surgeries are not only costly but also come with risks, especially for patients who may have complex heart conditions or other medical issues.
The study opens new avenues for designing less invasive, low-energy defibrillation devices. By capitalizing on the properties of the heart’s vulnerable window, scientists may be able to develop devices that selectively inhibit arrhythmias with a fraction of the energy current models require. Grigoriev suggests this technology could represent a paradigm shift in how we manage cardiac arrhythmias, moving toward treatments that minimize patient discomfort and improve overall safety.
Looking forward, the research team plans to explore clinical applications of this technology. With advancements in computational modeling and electrophysiology, there is potential to bring this ultra-low-energy defibrillation method closer to practical, real-world use. This development could offer a major improvement in arrhythmia treatment, marking a step toward gentler, more effective cardiac care.
Source: American Institute of Physics