Flexible electronics assist multi-functional catheters

In an improvement over open-heart surgery, cardiologists now use catheters to eliminate damaged heart tissue in certain patients, such as those with arrhythmias.

But this, too, can be a long and painful procedure as many catheters, with different functions, need to be inserted sequentially.

Now an interdisciplinary team, including researchers from Northwestern University and the the University of Illinois at Urbana-Champaign, has developed one catheter that can do it all.

This tool for cardiac ablation therapy has all necessary medical devices printed on a standard balloon catheter: a device for eliminating damaged tissue using heat, temperature and pressure sensors, an LED and an electrocardiogram (EKG) sensor.

The multi-functional catheter makes a minimally invasive technique for heart surgery even better, since both diagnostic and treatment capabilities are combined in one.

Stretchable electronics developed by Prof Yonggang Huang of Northwestern and John Rogers of the University of Illinois at Urbana-Champaign made the development of the catheter possible.

The ability of the electronics to stretch is important because it enabled the researchers to print all the necessary medical devices on a section of a standard endocardial balloon catheter where the wall is thinner than the rest.

There, the sensitive devices and actuators are protected during the catheter’s trip through the body to the heart. Once the catheter reaches the heart, the catheter is inflated and the thin section expands significantly.

Once the catheter is in place, the individual devices can perform their specific tasks. The pressure sensor determines the pressure on the heart, the EKG 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 (ablate) the tachycardia-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.

While the multi-functional catheter has not been used with humans, the researchers have demonstrated the utility of the device with anaesthetised animals.

Huang led the theory and mechanical and thermal design work at Northwestern. He and his colleagues’ contribution was to ensure the mechanical integrity of the device so there was no failure during significant stretching and to control temperature during cardiac ablation therapy. Prof Rogers at the University of Illinois at Urbana-Champaign led the design, experimental and fabrication work.

The pair also worked closely with MC10, a company that is commercialising the underlying technology for both medical and non-medical applications.