(ORDO NEWS) — A steady heartbeat rhythm is something that can easily fade into the background in our daily lives if little thought is given to the reliability of its pulse.
But for those who develop an arrhythmia, the situation is much more dangerous – their heartbeat is monitored and controlled by life-saving devices called pacemakers, which send controlled pulses to the heart to stop shaking and allow it to find its rhythm again.
Studying the wide range of ways in which the heart can stumble and stutter, turning into a trembling mess, often uses small animals as models.
But despite their convenience and ethical benefits, their size can make it difficult to monitor and respond to changes in their tiny hearts.
Now, a team of scientists led by biomedical engineer Philip Gutruff of the University of Arizona has developed an implantable device that makes it much easier to study small animal cardiology.
As a bonus, it could one day be the basis of an entirely new way to treat heart disease in humans.
The device has been designed to be flexible enough for smaller test subjects, providing the best resolution for monitoring their condition. electrophysiology of the heart.
Using light instead of electrical signals, it produces softer pulses when abnormal rhythms are detected.
Unlike the electrical signals of existing pacemakers, which can interfere with recording capabilities and leave physicians with a patchy picture of heart attacks, the use of light to stimulate the heart means the system can provide continuous recording of heartbeat patterns even when defibrillation is needed.
“Existing pacemakers basically register a simple arrhythmia, now shock!” explains Gutruf.
“But this device has a computer on board where you can enter various algorithms that allow you to more difficultly regulate the rhythm. It’s made for research.”
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, whereby excitable cells like heart or brain cells can be activated on demand with light.
In this case, mouse cardiomyocytes (heart muscle cells) were genetically engineered to express a blue-light-sensing membrane-bound protein. Turn on the light and the cells will start working.
The beauty of the device lies in its soft, thin-film arrays that diverge like flower petals and envelop the heart.
This snug fit is very different from how modern pacemakers are connected to the heart via one or two electrodes implanted in the organ.
People who have pacemakers installed may experience discomfort and cramping pain around the implant site. In some rare cases, they may even develop complex regional chest pain.
Stimulating the heart through one or two contact points also makes cardiac defibrillation less accurate than ideal.
“All cells inside the heart are affected at the same time, including pain receptors, and this is what makes pacing or defibrillation painful,” Gutruf explains. “It affects the heart muscle in general.”
Instead, a new device that only activates heart muscle cells that cause contraction and bypass pain receptors, the researchers hope it could offer a more convenient and accurate way to synchronize irregular heartbeats.
“While now we need to electrify the whole heart for this, these new devices can target much more accurately, making defibrillation more effective and less painful,” says Igor. Efimov, a biomedical engineer at Northwestern University.
As the team describes in their paper, the prototype device was implanted just outside the mouse chest with a special applicator and a single suture separating the heart rate. data over the infrared uplink.
The researchers first analyzed the geometry and mechanics of a beating mouse heart, using that information to design and laser fabricate a flexible four-prong mesh so that it can move with the heart. when he hit the beat.
By testing the wireless device on freely moving mice, the researchers showed that the device could detect abnormal rhythms and stimulate or “pace” the heart with millisecond precision and without the heat from light pulses damaging heart tissue.
The device’s accuracy in detecting abnormal heartbeats was also comparable to current commercially available wireless heart rate monitoring devices, the researchers report.
While the results of animal studies like this one are promising, it is still very early to use optogenetics in humans.
This method requires gene therapy (to make the cells light-sensitive) as well as an implantable electronic device to stimulate them in a controlled manner.
Although optogenetics has been used in clinical trials to treat rare hereditary eye diseases, the use of this technique to monitor and possibly treat cardiac abnormalities remains a novel approach that requires much more research, primarily in animals.
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.
More work also needs to be done to model the subtleties of cardiac arrhythmias and improve the methods of this particular device for detecting and correcting different types of arrhythmias, Gutruf and colleagues note. .
So, for now, the flower-like device is one of many that is an elegant research tool for studying arrhythmias and other heart problems as they occur, at least in animal models.
Contact us: [email protected]