3rd March 2014

3-D printed electronic membrane could prevent heart attacks

Using an inexpensive 3-D printer, biomedical engineers have developed a custom-fitted, implantable device with embedded sensors that could transform treatment and prediction of cardiac disorders.

An international team of biomedical engineers and materials scientists have created a 3-D elastic membrane made of a soft, flexible, silicon material, precisely shaped to match the heart's epicardium (its outer layer). Current technology is two-dimensional and cannot cover the full surface of the epicardium or maintain reliable contact for continual use without sutures or adhesives.

Tiny sensors can be printed onto this membrane that precisely measure temperature, mechanical strain and pH level, among other markers, or deliver a pulse of electricity in cases of arrhythmia. These sensors could assist physicians with determining the health of the heart, deliver treatment or predict an impending heart attack before a patient exhibits any physical signs.

"Each heart is a different shape, and current devices are one-size-fits-all and don't at all conform to the geometry of a patient's heart," says Professor Igor Efimov, at Washington University in St. Louis. "With this application, we image the patient's heart through MRI or CT scan, then computationally extract the image to build a 3-D model that we can print on a 3-D printer. We then mold the shape of the membrane that will constitute the base of the device deployed on the surface of the heart."

The video below shows a rabbit heart, kept beating outside the body in a nutrient and oxygen-rich solution. The new cardiac device – with its flexible network of sensors and electrodes – has been custom-designed to fit over the heart and contract and expand as it beats. If all goes well, a version for humans is expected in the next 10-15 years.

Ultimately, this membrane could be used to treat diseases of the ventricles in the lower chambers of the heart or could be inserted inside the heart to treat a variety of disorders – including atrial fibrillation, which affects 3 to 5 million patients in the United States.

"Currently, medical devices to treat heart rhythm diseases are essentially based on two electrodes inserted through the veins and deployed inside the chambers," says Efimov. "Contact with the tissue is only at one or two points, and it is at a very low resolution. What we want to create is an approach that will allow you to have numerous points of contact and to correct the problem with high-definition diagnostics and high-definition therapy."

Recently, Google announced it was developing a contact lens embedded with sensors to monitor glucose levels in diabetes patients. Efimov says the membrane his team has developed is a similar idea, but much more sophisticated.

"Because this is implantable, it will allow physicians to monitor vital functions in different organs and intervene when necessary to provide therapy," he says. "In the case of heart rhythm disorders, it could be used to stimulate cardiac muscle or the brain, or in renal disorders, it would monitor ionic concentrations of calcium, potassium and sodium."

The membrane could even hold a sensor to measure troponin – a protein expressed in heart cells and a hallmark of an impending heart attack. Ultimately, such devices will be combined with ventricular assist devices, Efimov says.

"This is just the beginning," he adds. "Previous devices have shown huge promise and have saved millions of lives. Now we can take the next step and tackle some arrhythmia issues that we don’t know how to treat."

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