Researchers at the University of Washington School of Medicine have made an intriguing discovery that could make radiation therapy a less invasive treatment for cardiac arrhythmias. The method appears to activate heart cells, helping them return to a youthful state and repairing tissue.
Arrhythmia is a condition in which the heart beats irregularly, which can lead to potentially dangerous health problems. It is the result of problems with the way electrical signals are transmitted through tissue, and one of the main treatments is called catheter ablation. This invasive procedure involves putting special tubes through arteries in the heart and a small burn, creating scar tissue that interrupts the signals.
What we know
A few years ago, a University of Washington team discovered a much less invasive alternative, radiation therapy, which is often used to treat cancer patients. When exposed to the heart, this therapy was found to improve arrhythmia symptoms just as well as catheter ablation, and possibly even better.
Radiation exposure was thought to produce scarring similar to the catheter ablation process, but observations showed that other factors were at work. Radiation therapy seemed to improve symptoms within days, instead of the months that catheter ablation might take. So in a new study, scientists found out what else might be going on.
What's the outlook?
Follow-up trials in mouse hearts have shown that the activity of a signaling pathway called Notch is temporarily increased. This increases sodium ion channels in the heart muscle, reducing arrhythmias.
Surprisingly, the Notch signaling pathway is usually inactive in adults. It plays a key role in the development of the heart's electrical system and then quiets down in adulthood. Activating this pathway with radiation seems to return the tissue to a healthier, "younger" state for a while. The beneficial effects have been seen to persist in patients for at least two years.
The team plans to study this further as a potential treatment for arrhythmia, and to find out the optimal dose of irradiation.
Source: nature, wustl.edu