University of British Columbia
Vancouver, BC, Canada

For every three individuals who have had a stent implanted to keep clogged arteries open and prevent a heart attack, at least one will experience restenosis — the renewed narrowing of the artery due to plaque buildup or scarring — which can lead to additional complications.

Now, a team led by UBC electrical and computer engineering professor Kenichi Takahata has developed a type of “smart stent” that monitors even subtle changes in the flow of blood through the artery, detecting the narrowing in its earliest stages and making early diagnosis and treatment possible.

The device uses medical-grade stainless steel and looks similar to most commercial stents. (Credit: University of British Columbia)

“We modified a stent to function as a miniature antenna and added a special microsensor that we developed to continuously track blood flow. The data can then be sent wirelessly to an external reader, providing constantly updated information on the artery's condition,” says Takahata.

The device uses medical-grade stainless steel and looks similar to most commercial stents. Researchers say it’s the first angioplasty-ready smart stent — it can be implanted using current medical procedures without modifications.

Research collaborator Dr. York Hsiang, a UBC professor of surgery and a vascular surgeon at Vancouver General Hospital, notes that monitoring for restenosis is critical in managing heart disease.

“X-rays such as CT or diagnostic angiograms, which are the standard tools for diagnosis, can be impractical or inconvenient for the patient,” says Hsiang. “Putting a smart stent in place of a standard one can enable physicians to monitor their patient’s health more easily and offer treatment, if needed, in a timely manner.”

The device prototype was successfully tested in the lab and in a swine model. Takahata, who holds patents for the technology, says his team is planning to establish industry partnerships to further refine the device, put it through clinical trials and eventually commercialize it.

The research is described in the May issue of Advanced Science. According to the article, “Enabling Angioplasty-Ready “Smart” Stents to Detect In-Stent Restenosis and Occlusion,” the smart stent, which is equipped with microscale sensors and a wireless interface, enables continuous monitoring of restenosis through the implanted stent. This electrically active stent functions as a radio-frequency wireless pressure transducer to track local hemodynamic changes upon a renarrowing condition. The authors note that the stent is devised and constructed to fulfill both engineering and clinical requirements while proving its compatibility with the standard angioplasty procedure.

The article explains that “prototypes pass testing through assembly on balloon catheters withstanding crimping forces of >100 N and balloon expansion pressure up to 16 atm and show wireless sensing with a resolution of 12.4 mmHg. In a swine model, this device demonstrates wireless detection of blood clot formation, as well as real-time tracking of local blood pressure change over a range of 108 mmHg that well covers the range involved in human. The demonstrated results are expected to greatly advance smart stent technology toward its clinical practice.”

How It Works

A pressure-microsensor-integrated wireless stent that is crimped on the balloon catheter is positioned at the targeted stenosis site in the artery. The smart stent is then deployed by balloon inflation to start self-diagnosing while scaffolding the narrowed artery after removal of the catheter; the stent’s resonant frequency is at its nominal level. In-stent restenosis changes local blood pressure and shifts the stent’s frequency as a sign of the problem; the implant is continuously monitored through a handheld wireless reader that sends out a warning of restenosis upon occurrence.

Engineering researcher Xing Chen, now a research associate at the Johns Hopkins School of Medicine, and Babak Assadsangabi, a postdoctoral fellow at UBC’s faculty of applied science, also contributed to the study.