Last summer, researchers at Northwestern University unveiled the first-ever transitional pacemaker, a fully implantable wireless device that dissolves harmlessly in the body after it is no longer needed. They now present a new smart version that is integrated into a coordinated network of four soft, flexible wireless sensors and control units located around the upper body.
The study will be published in the journal on Friday (May 27) Science. The work was supervised by John A. Rogers of Northwestern, Igor R. Yefimov and Dr. Rishi Aror.
The sensors interact with each other to constantly monitor various physiological functions of the body, including body temperature, oxygen levels, respiration, muscle tone, physical activity and electrical activity of the heart.
The system then uses algorithms to analyze this combined activity to autonomously detect abnormal heart rhythms and decide when and how often to stimulate the heart. All this information is transmitted to a smartphone or tablet so that doctors can remotely monitor their patients.
The new transient pacemaker and sensor / monitoring network can be used in patients who need temporary pacemaking after heart surgery or are expecting a permanent pacemaker. The pacemaker wirelessly collects energy from a network node, a small wireless device that fits snugly against a patient’s chest. This technology eliminates the need to use external equipment, including wires (or taps).
To allow the system to communicate with the patient, the researchers included a small wearable tactile feedback device that can be worn anywhere on the body. When sensors detect a problem (such as low battery, incorrect device placement, or pacemaker failure), the tactile device vibrates in certain patterns that alert users and notify them of the problem.
Submission from experts
“This is the first time we’ve combined soft, wearable electronics with transitional electronic platforms,” Rogers said. “This approach can change the way patients are treated, providing multi-node, closed-loop control of important physiological processes – through a wireless network of sensors and stimulators that works as it inspires complex biological cycles of feedback that control behavior in living organisms. .
“For temporary pacing, the system disengages patients from the monitoring and stimulation devices that keep them in the hospital. Instead, patients can recover in the comfort of their own home while maintaining the peace of mind of remote control. It will also reduce the cost of care and for other patients ”.
“In the current environment, temporary pacemakers require a wire that is connected to an external generator that stimulates the heart,” said Yefimov. “When the heart regains its ability to stimulate itself properly, the wire needs to be pulled. As you can imagine, this is a rather dramatic procedure of pulling the wire connected to the heart. We decided to approach this problem from another angle. corner. We have created a pacemaker that simply dissolves and does not need to be removed. This avoids the dangerous phase of pulling the wire. “
“Current pacemakers are quite smart and respond well to changing patients’ needs, ”Arora said. “But wearable modules do everything traditional pacemakers do and more. The patient mostly wears a small patch on his chest and gets real-time feedback to control the pacemaker. The pacemaker itself is not only bioresorbable but also controlled by a soft wearable patch. allows the pacemaker to respond to normal life activities without the need for implanted sensors. ”
Rogers is Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery Louis Simpson and Kimberly Cueri at McCormick School of Engineering in the Northwest and Feinberg School of Medicine at Northwestern University (CIEP). Yefimov is a professor of biomedical engineering at McCormick and a professor of medicine (cardiology) at Feinberg. Arora is a professor of medicine in Feinberg and co-director of the Center for Arrhythmia Research.
“Network of body areas”
A pioneer of bioelectronics, Rogers and his lab have been developing soft, flexible wireless wearables and biodegradable electronic technology for nearly two decades. In a new study, Rogers and his colleagues combined and coordinated their bioabsorbable lead-free pacemaker with four different devices with a skin interface to work together. Skin-mounted devices are soft, flexible and can be gently detached after use, eliminating the need for surgical removal. The pacemaker naturally dissolves in the body after a period of need.
“Body Grid” includes:
- Pacemaker without battery, which can temporarily control pacing;
- Cardiac module located on the chest to provide nutrition and control the stimulation parameters of the implanted pacemaker, as well as experience electrical activity and heart sounds;
- A module of hemodynamics that is located on the forehead to experience pulse oximetry, tissue oxygenation and vascular tone;
- Respiratory module located at the base of the throat to control cough and respiratory activity; and
- A module with multiple tactile feedback that vibrates and pulsates in different models to communicate with the patient.
“We wanted to demonstrate that several different types of devices can be deployed, each of which performs critical functions in wireless coordination throughout the body,” Rogers said. “Some feel. Some provide power. Some stimulate. Some provide control signals. But they all work together, trading information, making algorithm-based decisions and responding to changing conditions. Vision of multiple bioelectronic devices talking to each other and performing different functions in different relevant anatomical locations is a border area that we will continue to pursue in the future. “
New advances, pace on demand
Since the Northwestern transient pacemaker was first introduced a year ago, researchers have made many improvements to the technology. While the previous device was flexible, the new device is flexible and stretches, allowing you to better adapt to the changing nature of a beating heart.
The new iteration also uses a biocompatible adhesive developed in the laboratories of Rogers and Efimov. The glue allows a light, thin device to gently laminate to the surface of the heart without the need to suture. Another new benefit: because the transient pacemaker dissolves slowly and safely, it releases an anti-inflammatory drug to prevent reactions to a foreign body.
Perhaps the most effective achievement is the device’s ability to provide on-demand stimulation depending on when the patient needs it. Synchronized with a pacemaker, a chest-mounted cardiology module records a real-time electrocardiogram to monitor cardiac activity. In the study, the researchers compared this wireless technology with a gold standard electrocardiogram and found that it is as accurate and precise as clinical class systems.
“The heart module literally tells the pacemaker to apply the stimulus to the heart,” Efimov explained. “When normal activity is restored, he stops corrupting. This is important because if you stimulate the heart when it is not needed, you risk causing an arrhythmia. ”
“The incentive system is completely autonomous,” said He Sik Choi, a graduate student at Rogers Laboratory and one of the authors of the paper. “It can automatically detect a problem and apply treatment. It’s easy and autonomous with minimal external needs.”
Healthcare is fragile enough for newborns
Rogers, Yefimov, Arora and their team believe their system will be most beneficial to the most vulnerable patients. Each year, about 40,000 babies are born with a hole in the wall that separates the upper chambers of their heart. About 10,000 of these cases are life-threatening and require immediate surgical intervention. After surgery, 100% of children receive a temporary pacemaker.
“The good news is the temporary situation,” Yafimov said. “After about five to seven days, the heart regains its ability to stimulate itself and no longer needs a pacemaker. The pacemaker removal procedure has improved significantly over the years, so the number of complications is low. But we could free these children from wires connecting to an external generator. relieve them of the need for a second procedure. “
The study was supported by the Leducq Foundation (RHYTHM project and award R01-HL141470), the American Heart Association (award number 19PRE34380781), the National Science Foundation (award number 1842165) and the National Institutes of Health (award number 5K959-HL1). -02). The first authors of the article are He Sik Choi, Hyun Jeong and Rose Yin.