No further intervention necessary: If the heart only needs a clock generator temporarily, patients could soon benefit from a pacemaker, the materials of which are completely broken down by the body after use. As the developers report, the implant does not require any problematic connections or batteries – it is powered wirelessly by an external device. The transient pacemaker has already proven its functionality and degradability in animal experiments.
Normally, the heart takes care of its own rhythmic beat – the sinus node emits electrical impulses and thus ensures the muscle contractions. But with some people this system is disturbed – the pump organ does not run smoothly and medical intervention is necessary: An artificial clock is used to treat severe cardiac arrhythmias – a pacemaker. But in many cases only bridging treatment is necessary. “Some patients only need a pacemaker temporarily, for example after an open heart surgery, a heart attack or a drug overdose,” says Rishi Arora of Northwestern University in Evanston. After the heart has stabilized, the pacemaker system can then be removed.
So far problematic bridging procedures
However, the current standard methods of temporary cardiac assistance are associated with risks and unpleasant side effects for the patient. To do this, surgeons sew pacemaker electrodes onto the heart muscle. They are connected to wires that exit the front of the patient’s chest and are connected to an external pacemaker box that provides the electrical pulses. When the temporary pacemaker is no longer required, the electrodes are removed again. This procedure creates the risk of slippage, infection, tissue damage and bleeding when the electrodes are removed. It is also uncomfortable and frightening for patients to be “wired” during treatment. Against this background, Arora and his colleagues came up with the idea of developing an implantable pacemaker for bridging purposes, which disappears by itself after its function and does not require any connections.
The highlight of their concept is that all components of the pacemaker are made of biocompatible materials that are naturally dissolved by the body after a certain period of time and do not leave any problematic breakdown products. The carrier material of the device is made of plastic-like biopolymers, which have also been used in medicine before and are broken down into organic acids, among other things. The scientists report that even the silicon-containing parts of the biodegradable pacemaker, which ensure its electronic functions, break down into completely harmless substances. “We build these devices from several different types of safe, bioabsorbable materials,” says co-author John Rogers. By varying the composition and thickness of the materials in the device, scientists can control exactly how long it remains functional before it completely dissolves over a period of weeks. “We guarantee stable operation over a period of time that is slightly longer than clinically necessary,” explains Rogers.
Refined, ephemeral medical technology
The fully implantable device is wafer-thin and weighs less than half a gram, and the electrodes are soft and flexible on the surface of the heart to deliver the electrical impulses. A wireless supply is provided for the necessary energy: It is based on what is known as resonance-inductive coupling, through which some cell phones or electric toothbrushes, for example, can wirelessly supply energy. The tiny device has a receiver that draws energy from a transmitter unit that is attached to the chest. “Instead of using wires that can cause infections or become loose, this system can be completely implanted and activated and controlled from the outside,” explains Arora.
The researchers have already been able to confirm in animal experiments that the transient pacemaker keeps its promises: the prototype was able to successfully stimulate the hearts of mice, rats, rabbits and dogs and was completely broken down within three months after implantation. “Our system overcomes the main disadvantages of traditional temporary procedures and thus offers more security, potential for cost savings and relief for patients. This type of device could represent the future of temporary pacemaker technology, ”concludes Rogers.
Finally, co-author Igor Efimov of George Washington University in Washington DC also highlights the broader potential of bioabsorbable medical technology: “The degradable materials on which this technology is based make it possible to create a whole range of diagnostic and therapeutic transient devices that could be used to treat and monitor diseases. This opens a new chapter in medicine and biomedical research, ”says Efimov with conviction.
Source: Northwestern University, Article: Nature Biotechnology, doi: 10.1038 / s41587-021-00948-x
http://dx.doi.org/10.1038/s41587-021-00948-x