The therapy detects fast arrhythmias in the atrium of a rat's heart and sends a signal to a LED device placed near the heart. "The flash of light from this LED then causes the heart to generate an electric current itself to halt the arrhythmia," said lead investigator Daniel Pijnappels at Leiden University in the Netherlands. "This is made possible by using gene therapy to introduce specific light-sensitive proteins into the heart. This restores the heart's normal rhythm immediately and automatically," he added.

According to the researchers, this could represent a great improvement on the current way of stopping atrial fibrillation. Atrial fibrillation is the most common heart rhythm disorder in clinical practice. The current treatment, known as cardioversion, is based on administering an electric shock to the heart, which has to be done in the hospital under general anaesthesia because of pain.

For many patients, this is the only treatment to immediately stop atrial fibrillation because drugs or an operation are ineffective. "The bioelectronic defibrillator can stop atrial fibrillation without an electrical shock. In this way, the heart can be reset in a fully automated manner and at any time," Pijnappels said, in the paper reported in the journal Science Translational Medicine.

"We anticipate that this treatment for atrial fibrillation could improve both the patient's quality of life and their prognosis," he added. However, considerable research is still needed before a treatment can be arrived at that is suitable for human patients, the researchers noted.