This temporary pacemaker melts away once the job is done
A team of more than four dozen researchers has invented a remarkable new form of medical technology.
Their network of wireless devices — including a pacemaker that dissolves in the body — keeps tabs on body temperature, oxygen levels, respiration, muscle tone, physical activity, and the heart. If necessary, the pacemaker can zap the heart back into rhythm.
“For temporary cardiac pacing, the system untethers patients from monitoring and stimulation apparatuses that keep them confined to a hospital setting. Instead, patients could recover in the comfort of their own homes while maintaining the peace of mind that comes with being remotely monitored by their physicians," says materials scientist John Rogers, one of the co-authors. He claims the device could reduce costs and free up hospital beds.
The invention is described in a paper published Friday in the peer-reviewed journal Science.
Stretchier, stickier, and better-connected than previous models
An earlier version of the pacemaker was unveiled last summer. Since then, Rogers and his colleagues have made several improvements to the device. The new version stretches more easily, accommodating the constant movement of a beating heart. It also sticks to the organ using a biodegradable adhesive, which contains an anti-inflammatory drug to prevent the body from attacking the device with a dangerous immune response as it breaks down.
The pacemaker itself works with several other units to monitor the patient. A module attached to the outside of the chest takes in the data and uses an algorithm to detect problems.
“The cardiac module literally tells the pacemaker to apply stimulus to the heart,” says biomedical engineer Igor R. Efimov, another co-author. “If normal activity is regained, then it stops pacing. This is important because if you stimulate the heart when it’s unnecessary, then you risk inducing arrhythmia.”
A clinical version has to work — and be safe.
This technology holds tremendous promise, but it also comes with a lot of unanswered questions, according to biomedical researcher Wolfram-Hubertus Zimmermann. He says that determining — and minimizing — the frequency of errors is key to making this technology viable for use in a clinical setting.
"This is not a trivial task because such devices must be able to make highly accurate
ECG recordings for a clear dissection of signal from noise, [which is] a common problem in contemporary pacers and defibrillators," he says. The improved materials and new AI-powered algorithms may be able to help.
Zimmermann says privacy is another concern. "Implanted sensors will collect highly personalized data, which could be misused or even manipulated," he says. It's paramount that medical authorities establish rigorous data protection measures, and patients should be prepared in case of a nightmare scenario: "an unwanted loss of control" of the device, he says.
It will be some time before cardiologists are implanting these devices in ordinary patients. The new device has succeeded in tests with rats and dogs. It also operated as expected when trialed on a donated human heart. But the system hasn't yet been tested on a real human yet.
Temporary postoperative cardiac pacing requires devices with percutaneous leads and external wired power and control systems. This hardware introduces risks for infection, limitations on patient mobility, and requirements for surgical extraction procedures. Bioresorbable pacemakers mitigate some of these disadvantages, but they demand pairing with external, wired systems and secondary mechanisms for control. We present a transient closed-loop system that combines a time-synchronized, wireless network of skin-integrated devices with an advanced bioresorbable pacemaker to control cardiac rhythms, track cardiopulmonary status, provide multihaptic feedback, and enable transient operation with minimal patient burden. The result provides a range of autonomous, rate-adaptive cardiac pacing capabilities, as demonstrated in rat, canine, and human heart studies. This work establishes an engineering framework for closed-loop temporary electrotherapy using wirelessly linked, body-integrated bioelectronic devices.
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