Using a combination of human heart models and experiments with mice, scientists at Johns Hopkins University, Baltimore, MD, and Germany's University of Bonn have shown that beams of light may help patients with heart rhythm disorders. The technique supports new implantable defibrillators and offers a potential replacement over electric-shock treatments.

A graphic shows an abnormal arrhythmia (left) and an orderly heartbeat (right).
(Credit: Patrick M. Boyle/Johns Hopkins University)

Current devices deliver pulses of electricity that are often painful and can damage heart tissue. Light-based treatment, the researchers say, should provide a safer and gentler remedy for patients at high risk of arrhythmia, an irregular heartbeat that can cause sudden cardiac death within minutes.

Light-sensitive proteins, embedded in living tissue, enable the use of light sources to modify electrical activity in cells.

"We are working towards optical defibrillation of the heart, where light will be given to a patient who is experiencing cardiac arrest, and we will be able to restore the normal functioning of the heart in a gentle and painless manner," said Natalia Trayanova, a professor in JHU's Department of Biomedical Engineering and a core faculty member in the university's Institute for Computational Medicine who supervised the research at Johns Hopkins.

The Bonn team conducted tests on beating mouse hearts, whose cells had been genetically engineered to express proteins that react to light and alter electrical activity within the organ. When the Bonn researchers triggered ventricular fibrillation in the mouse heart, a light pulse of one second applied to the heart was enough to restore normal rhythm.

Trayanova's team at Johns Hopkins performed an analogous experiment within a detailed computer model of a human heart, one derived from MRI scans taken of a patient who had experienced a heart attack and was now at risk of arrhythmia.

"Our simulations show that a light pulse to the heart could stop the cardiac arrhythmia in this patient," said Patrick M. Boyle, a Johns Hopkins biomedical engineering research professor who was also a lead author of the journal article.

According to the researchers, the promising light treatment will still require much more time and research before the method can become a commonplace medical procedure.