Stents are usually passive devices, implanted into clogged arteries to prop them open and prevent heart attacks. Unfortunately, it's all too common for the artery to continue to narrow around the implant, causing further complications. Now, researchers at the University of British Columbia (UBC) have developed a surgery-ready smart stent that keeps watch for the early warning signs of narrowing arteries, and sends out a wireless signal to alert the patient and doctors.

Implanting stents to treat heart disease has been a relatively successful procedure since it was introduced in the 1980s, but they do bring their own risks with them. One of the most common is restenosis, where nearby tissue grows around the stent and narrows the artery once again. This is normally monitored through CT scans, but that's not the most convenient or reliable method.

To combat the problem, scientists have been developing better stents. Last year, Colorado State engineers coated titanium implants in superomniphobic surfaces, meaning they repelled blood so effectively that platelets wouldn't build up and cause clots.

In the new work, the UBC team gave the stent a more active role. The smart stent is built with a tiny sensor that constantly keeps track of changes in the rate of blood flow, and when it detects small anomalies that are associated with the early stages of restenosis, it pings the patient or doctors to do something about it before the condition worsens.

"We modified a stent to function as a miniature antenna and added a special micro-sensor that we developed to continuously track blood flow," says Kenichi Takahata, lead researcher on the study. "The data can then be sent wirelessly to an external reader, providing constantly updated information on the artery's condition."

The stent itself is made of medical-grade stainless steel, and because it's so similar to existing devices, the team says it's angioplasty-ready, meaning it can be implanted using existing procedures. Once there, the smart stent should remove the need for regular CT scans to check for signs of restenosis.

When readings are being taken, it's powered wirelessly by electromagnetic waves that are emitted by an external antenna placed against the skin.

The team tested the device in the lab and in pigs, and found that worked as hoped. With promising early results, the researchers now plan to continue refining the stent, to get it ready for human clinical trials.

The research was published in the journal Advanced Science.