New stretchable device promises to make ablation simpler

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An interdisciplinary team has developed a catheter combining diagnostic and treatment tools to make ablation simpler. The new tool has all necessary medical devices printed on a standard balloon catheter: a device for eliminating damaged tissue using heat, temperature and pressure sensors, a light-emitting diode (LED) and an electrocardiogram sensor.

The stretchable electronics were developed by Yonggang Huang, Northwestern University and John Rogers, University of Illinois at Urbana-Champaign. The research was published on 6 March 2011 in the journal Nature Materials.

“The use of one catheter to achieve all these functions will significantly improve clinical arrhythmia therapy by reducing the number of steps in the procedure, thereby saving time and reducing costs,” said Huang.

In conversation with collaborating cardiologists, Moussa Mansour, Harvard Medical School; Marvin Slepian, University of Arizona; and Joshua Moss, and Brian Litt, University of Pennsylvania, Huang and Rogers recognised that their stretchable electronics could improve the surgical tools currently used in cardiac ablation therapy.

The electronics Huang and Rogers use in this study are based on a “pop-out” design of interconnects, similar to their early design for stretchable electronics but with much larger – approximately 130% – stretchability.

“Our challenge was how to make the electronics sustain such a large stretch when the thin wall expands under pressure,” Huang said. “We devised what we call a ‘pop-out interconnect’ that performs very well. We did not expect the electronics to sustain a stretch nearly three times the section’s length.”

Once the catheter is in place, the individual devices can perform their specific tasks when needed. The pressure sensor determines the pressure on the heart; the electrocardiogram sensor monitors the heart’s condition during the procedure; the LED sheds light for imaging and also provides the energy for ablation therapy to eliminate the arrhythmia-inducing tissue; and the temperature sensor controls the temperature so as not to damage other, good tissue.

The entire system is designed to operate reliably without any changes in properties as the balloon inflates and deflates. “It demands all the features and capabilities that we have developed in stretchable electronics over the years in a pretty aggressive way,” Rogers said. “It also really exercises the technology in an extreme, and useful, manner – we put everything on the soft surface of a rubber balloon and blow it up without any of the devices failing.”

These devices can deliver critical high-quality information, such as temperature, mechanical force, blood flow and electrogram, to the surgeon in real time. While the multifunctional catheter has not been used with humans, the researchers have demonstrated its utility with anaesthetised animals.

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