Electrical signals tell the heart to contract, but when the signals form spiral waves, they can lead to dangerous cardiac events like tachycardia and fibrillation. Researchers at the Georgia Institute of Technology and clinicians at Emory University School of Medicine are bringing a new understanding to these complicated conditions with the first high-resolution visualizations of stable spiral waves in human ventricles.
“Clinicians have known for decades that spiral waves of electrical activity can occur in the heart, and researchers have done experiments in animal and human hearts before,” said School of Physics Professor Flavio Fenton. “However, this is the first time the evolution of relatively stable spiral waves of voltage and calcium in the ventricles of human hearts have been mapped at very high spatial and temporal resolution.”
Studying live hearts from heart transplant patients gives a rare window into the detailed behavior of the heart during conditions that are difficult to treat like fibrillation. As a result, doctors can gain a better understanding of how spiral waves begin and are sustained, which can lead to new therapies.
The present work has been part of a decade-long collaboration between the Georgia Tech School of Physics and the Emory School of Medicine. The researchers published their latest findings, “Direct observation of a stable spiral wave reentry in ventricles of a whole human heart using optical mapping for voltage and calcium” and “Spiral wave breakup: Optical mapping in an explanted human heart shows the transition from ventricular tachycardia to ventricular fibrillation and self-termination,” in the journal Heart Rhythm.
Mapping the Heart
To generate the conditions for spiral waves, the researchers applied timed electric shocks to the heart. Then, to visualize and record the spiral waves, they injected florescent dyes for voltage and calcium into the blood substitute that keeps the heart alive. The changes in light intensity enable them to record signals across the heart tissue, a technique known as optical mapping.
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