Pacemakers are small surgically implanted electronic devices that correct irregular heartbeats. They are in no way a new technology, having exited in various incarnations for decades. One memorable version from the 1970s is actually nuclear-powered, transforming the heat from decaying plutonium into electrical energy for zapping heart muscles into rhythm. The Los Alamos National Laboratory (one of the United States’ largest nuclear facilities) handles disposal of the devices upon their owners’ expiration, as they are radioactive.
Recently, researchers at the University of Illinois and Washington University have produced a novel pacemaker prototype that pushes the technological envelope. The new pacemaker doesn’t run on nuclear energy, but instead makes use of the incredible precision of computer modeling and 3D printing. The end result is a stretchy sleeve embedded with sensors and electrodes that fits over the heart like a second skin.
The first step in manufacturing the device was to make an exact computer model of the target heart – in the case of this particular study, a rabbit heart. The image is generated through the use of high-resolution medical imaging technologies, which combine multiple images to generate a highly detailed 3D computer model of the organ. This image is then compressed into a file, and sent to a machine known as a 3D printer.
According to the informational website 3dprinter.net, 3D printers “create a three dimensional object by building it layer by successive layer, until the entire object is complete. It’s much like printing in two dimensions on a sheet of paper, but with an added third dimension: UP. The Z-axis.”
“Each of these printed layers is a thinly-sliced, horizontal cross-section of the eventual object. Imagine a multi-layer cake, with the baker laying down each layer one at a time until the entire cake is formed” concludes the 3dprinter.net description.
The printer translates the computer heart model into an actual – and extremely accurate – plastic replica by building it layer-by-layer from the bottom up. This replica is then used as a template for creating a form-fitting sleeve.
“The goal,” said lead researcher John Rogers to ABC news “was to create a membrane that fit tightly but not so tightly that it interfered with the normal beating of the heart.”
Ideally, researchers wanted the sleeve to behave like a normal part of the heart’s anatomy: the pericardium. This thin, membranous structure encloses the heart and provides protection and lubrication to the heart as it expands and contracts, always in close contact with the restive organ. By using the plastic model, they were able to create an artificial sleeve that performs in much the same manner.
Creating a synthetic pericardium was one thing, but turning it into a pacemaker required integration of electronics. Metallic circuits, however, are not commonly known for being stretchy. The question of how to design electronics that could match the movements of the heart without being broken was solved by John Rogers, the lead researcher as well as a materials engineer.
The answer turned out to be quite simple: the circuits were designed in S-shaped curves, giving them “slack” to use as they expanded. With this final hurdle cleared, the research team put their device to the test: the pacemaker was able to keep the rabbit heart beating perfectly.
“This artificial pericardium is instrumented with high quality, man-made devices that can sense and interact with the heart in different ways that are relevant to clinical cardiology” John Rogers told the Independent in summary.
Within the next ten to fifteen years, custom-fit pacemakers could be used to monitor and correct any number of common heart conditions. Furthermore, because computer modeling and 3D printing make these devices so customizable, the therapies they offer can be similarly flexible and precise. Before these pacemakers can go to market, they will need to pass the stringent approval processes of the FDA. However, given the notable lack of radioactive isotopes, one could be excused for being optimistic about their chances.
