A team of scientists led by biomedical engineer Philip Gutroff of the University of Arizona has developed an implantable device that makes it much easier to study heart disease in small animals.
And one day, this could be the basis for an entirely new way to treat heart disease in humans.
The device is designed to be flexible enough for smaller subjects, allowing for higher accuracy in cardiac electrophysiology monitoring. Using light instead of electrical signals, it emits lighter vibrations when abnormal rhythms are detected.
And unlike the electrical signals from existing pacemakers, which can interfere with their recording capabilities and leave doctors with an incomplete picture of heart attacks, the use of light to stimulate the heart means the system can provide continuous recording of heart rate patterns — even when defibrillation is needed.
The device has only been tested in mice so far, but the researchers have developed it for more precise and possibly less painful stimulation of the heart. It works using a technique called optogenetics, in which excitable cells, such as heart or brain cells, can be activated on demand using light. In this case, mouse heart muscle cells were genetically engineered to express a membrane-bound protein that is sensitive to blue light.
The beauty of the device lies in its delicate, soft arrays that bloom like flower petals and envelop the heart. This snug fit is somewhat different from how modern defibrillators are connected to the heart via one or two electrodes implanted in the organ.
Stimulating the heart with one or two contact points also makes defibrillation less accurate than ideal.
“All the cells inside the heart are affected at the same time, including pain receptors, and that’s what makes the defibrillator painful,” explains Gutrov. “It affects the heart muscle as a whole.”
Instead, with this new device, which only activates the heart muscle cells that cause the contraction and bypass of pain receptors, the researchers hope it will provide a more convenient and accurate way to synchronize irregular heartbeats.
As the team describes in their paper, the prototype device was implanted outside the thorax of a mouse using a custom-made applicator and a single suture, and heart rate data was transmitted via infrared.
The researchers first analyzed the engineering and mechanics of a beating mouse heart, using this information to design and manufacture a laser for a flexible four-tooth grid so that it can move with the heart as it beats in rhythm.
By testing the wireless device on freely moving mice, the researchers demonstrated that the device can detect abnormal rhythms and stimulate the heart, or “rhythm,” to the millisecond – and without the heat of the light pulses damaging heart tissue.
The researchers reported that the device’s accuracy in detecting abnormal heartbeats is also comparable to commercially available wireless heart rate monitors.
While results from animal studies like this are promising, it is still too early to use optogenetics in humans. This method requires gene therapy (to make the cells sensitive to light) as well as an implantable electronic device to stimulate them in a controlled manner.
While optogenetics has been used in clinical trials to treat rare genetic eye diseases, the use of this technology to monitor and possibly treat heart disease is still a novel approach that primarily requires more animal research.
There are many challenges that need to be addressed, including the safe and efficient delivery of the genetic instructions encoding light-sensitive proteins to heart cells.
Gutroff and colleagues note that more work needs to be done to model the complexities of arrhythmias and improve the methods of this particular device to detect and correct different types of arrhythmias.
So, for now, the flower-like device is just one of many that is an elegant research tool for studying arrhythmias and other heart problems as they occur, at least in animal models.
The study was published in Scientific achievements.
Source: Science Alert.