Stretchable electronics get the heart back on track
By Ben Coxworth
March 9, 2011
When a patient has an arrhythmia (an irregular heartbeat), cardiologists will often treat the disorder by inserting two tube-like catheters into the patient's heart. The first catheter is used for mapping out the heart tissue, identifying the location of cells that are causing the arrhythmia. The second catheter, which has an electrode on the end, is then directed to those locations, where it kills the aberrant cells in a process known as ablation. Scientists have recently developed a single catheter with added stretchable electronics, however, that does both jobs in one step.
The team from the University of Illinois at Urbana-Champaign laminated a flexible meshwork of linked sensors and electrodes onto a conventional endocardial balloon catheter. Such catheters are typically inserted into constricted blood vessels or valves. As the catheter is inflated, it gently presses against the insides of the blood vessel, helping to open it up.
In this case, as the catheter makes contact with the cardiac muscle, the sensors measure electrical activity, temperature, blood flow, and pressure. Based on this data, the locations of irregularly-beating cells are established. The electrodes adjacent to those locations proceed to ablate the cells, after which the catheter is deflated and removed.
"It's all in one, so it maps and zaps," said project leader John A. Rogers, a professor of materials science and engineering. "The idea here is instead of this single-point mapping and separate single-point zapping catheter, have a balloon that offers all that functionality, in a mode that can do spatial mapping in a single step. You just inflate it right into the cavity and softly push all of that electronics and functionality against the tissue."
One of the team's biggest challenges was ensuring that the electronics in the wide, inflated middle of the catheter performed the same as those on its narrower, less inflated ends. To do so, they located the sensors and electrodes on tiny rigid "islands," that stay the same regardless of inflation. Those islands are linked by coiled wires that are able to compensate for the stretching and contracting of the rubber.
The catheter has been demonstrated successfully on live animal models.
Rogers is now looking towards increasing the amount of sensors and electrodes on the device, so that both mapping and zapping can be done with more precision, thus minimizing the amount of heart tissue ablated. He is working on commercializing the technology, and sees it being used in other biomedical and non-medical applications.
The research was published this month in the journal Nature Materials.
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