New defibrillation devices can save lives using 1,000x less electricity

Irregular heart rhythms, known as fibrillation, can disrupt the heart's ability to pump blood effectively. These chaotic contractions can affect either the atria or ventricles, leading to severe health issues. Ventricular fibrillation (VF) often causes sudden cardiac death, which was responsible for over 370,000 deaths in the U.S. in 2019 alone.

On the other hand, atrial fibrillation (AF), while not immediately fatal, significantly increases the risk of strokes, heart failure, and dementia.

Globally, AF is a growing epidemic. A 2010 study revealed that 33.5 million people worldwide suffered from AF, with 5 million new cases emerging annually. Treatment for fibrillation often involves a high-energy electric shock that resets the heart’s rhythm. Although effective, these shocks can cause intense pain, anxiety, and even long-term cardiac tissue damage.

Efforts to develop less painful, low-energy defibrillation techniques have been ongoing for years. One early approach used time-periodic electric fields to synchronize heart rhythms by inducing spiral wave drift. While this reduced energy use, it was limited by the complexities of heart tissue structure.

Another promising method, Low Energy Anti-tachycardia Pacing (LEAP), employs a series of low-energy pulses aimed at restoring rhythm without high-voltage shocks. LEAP has demonstrated success in both theoretical and experimental studies, reducing energy use tenfold compared to single-shock methods.

Recent advancements have further refined LEAP. Researchers have proposed varying the time intervals between pulses to optimize energy use and improve defibrillation outcomes. In clinical trials, some pulses were even found to fall below the threshold of pain, marking a significant step toward painless treatment.

Despite these advancements, challenges remain. Frequent use of defibrillation therapies, as seen in patients with implantable cardioverter defibrillators (ICDs), can drain device batteries and necessitate replacement surgeries, which carry their own risks. Studies show that ICDs might need to address atrial tachyarrhythmias as frequently as seven times per patient per month. These repeated treatments could potentially offset the energy savings of low-energy protocols.

In a groundbreaking study published in Chaos by AIP Publishing, researchers from Sergio Arboleda University and the Georgia Institute of Technology explored new ways to reduce defibrillation energy even further. Using computer models of the heart’s electrical activity, they tested different voltage applications to identify ultra-low-energy defibrillation methods.

“The results were not at all what we expected,” said Roman Grigoriev, one of the study's authors. “We learned that ultra-low-energy defibrillation is not about wave synchronization but rather about whether excitation waves can cross tissue regions that haven’t fully recovered from previous activity.”

The team used an adjoint optimization method, which adjusts voltage inputs over time to achieve the desired defibrillation effect. By continuously tweaking the electric field over an extended period, they found that irregular heart activity could be terminated with far less energy than current protocols require.

This approach capitalizes on the heart’s “vulnerable window,” a period during which small changes in electrical input can determine whether an excitation wave successfully propagates. By carefully modulating the electric field during these sensitive intervals, the team effectively blocked the propagation of chaotic waves.

“Our study shows that pain and tissue damage can be completely eliminated with the right low-energy protocols,” Grigoriev explained. “Current methods still require significant power, particularly for ICDs. Replacement surgeries, which are necessary when device batteries deplete, pose serious health risks.”

These findings could revolutionize cardiac care. The discovery that defibrillation can be achieved with significantly less energy offers hope for safer, more comfortable treatments. By focusing on long-term optimization of defibrillation protocols, researchers aim to reduce both the physical and psychological burden on patients.

As the search for even lower-energy solutions continues, the potential benefits extend beyond immediate patient comfort. Reducing the power demands of defibrillation could increase the lifespan of ICDs, decrease the frequency of invasive surgeries, and lower healthcare costs associated with device maintenance.

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