Inside the coronary arteries of millions of americans are stents, metal mesh tubes the length of a dime that prop open narrowed blood vessels to help prevent heart attacks. But in about a quarter of patients, scar tissue builds up in and around the stents three to six months after they're inserted, threatening to reclog arteries. Electrical engineer Yogesh Gianchandani and his team at the University of Michigan have designed a stent that can monitor blood pressure as an early warning sign of renarrowing. The researchers attached a tiny, flat pressure sensor to the stent and modified the pattern of the wire mesh so that it acts as an antenna. The stent wirelessly transmits pressure and flow information through the skin to an external device held against the chest. Gianchandani says the device could allow patients to monitor their blood pressure at home, saving repeated trips to the cardiologist and avoiding invasive procedures to check for arterial reclogging. The researchers have tested their prototype in simulated arteries and are now fine-tuning the device. They plan to have completed animal tests in about two years and hope to have the "stentenna" on the market in three to five years.