A 15-centimeter wireless sensor, recently approved by the FDA, holds the promise of reducing hospitalizations by allowing automated early detection of heart failure. The noninvasive device, which costs a few hundred dollars and adheres to a patient’s chest, monitors indicators of heart health–including heart and respiration rates, levels of patient activity, and even the accumulation of body fluid–as patients go about their daily lives.

Part of a technology platform now being marketed by Corventis, a startup in San Jose, CA, the waterproof sensor beams data to a special cell-phone-like gadget in the patient’s pocket or home. From there, the data is wirelessly transmitted to the company’s servers. Algorithms detect anomalies and transmit data to physicians via the Web or a mobile device, drawing attention to patients who need immediate care.

“We can transmit data from a patient to servers that can process the data–all without the patient knowing about it–24-7,” says Ed Manicka, the company’s president. “Your patient could be in Singapore, could be in Brussels, or could be across the room from you. And you can look at data from a website, or from an iPhone. Our system allows the computer to watch a patient all the time, not requiring the physician to continually look at data and act on it.”

While some technologies exist that can do much of the same job, they are bulky and impractical or must be surgically implanted. “This is much more unobtrusive in people’s daily lives,” says Eric Topol, a cardiologist who directs the Scripps Translational Science Institute, a medical research center in La Jolla, CA.

In patients with heart disease, fluid buildup in the lungs leads to shortness of breath, places pressure on pulmonary arteries, and threatens to cause heart failure, requiring hospitalization to remove fluid. However, if the disease is caught early, before the patient feels symptoms, hospitalization can be avoided by giving the patient diuretics. Topol says that the Corventis device is unique in including an impedance detector, which measures the buildup of body fluid through an indirect electrical measurement. The buildup of body fluid serves as a proxy for the buildup of fluid in the lungs.

“We’ve never had that before for remote monitoring,” Topol says. Beyond warning of heart failure through fluid detection, the device includes an accelerometer that tells if a person is generally less active–a sign that he is in distress–or not lying flat at night, which is another proxy measurement for fluid buildup in the lungs. (Lying flat makes the resulting shortness of breath worse, and sufferers will often sleep propped up on pillows.)

A clinical trial evaluating whether the device can predict heart failure–the technical term is “decompensated heart failure”–is under way and nearly complete, Corventis says. Heart-failure decompensation is the leading cause of hospitalization in Medicare patients, with more than a million U.S. hospitalizations a year costing tens of billions of dollars. “The projections are that if you can do remote monitoring for heart failure, it would save $20 billion in hospitalizations each year,” says Topol.

While scientists know that the device measures fluid accurately, it’s not yet clear whether having access to this information will ultimately reduce the incidence of hospitalization. This issue has plagued other cardiac monitoring devices, which accurately detected cardiac abnormalities but in the end failed to significantly improve clinical outcomes. “Intuitively, it’s really very exciting, but we still have to prove it,” says Topol. “But at least now there is a technology where you could see that the possibility is emerging.”

The company is also conducting a clinical trial to see if the sensor can diagnose sleep apnea through changes in respiration and blood oxygen levels. (Corventis plans to integrate a blood oxygen sensor in a future version of the device.) A third trial–to determine whether the device can predict imminent heart attacks by detecting subtle changes in heart rate and rhythm–is set to begin later this year, Manicka says.

A second Corventis sensor under review by the FDA will do more fine-grained capture of heart-rhythm disturbances. This device could detect subtle changes in heart patterns suggestive of arrhythmias such as atrial fibrillation, which is associated with increased stroke risk and is diagnosed in 835,000 Americans each year.

With these kinds of small, unobtrusive wireless health sensing and analytic technologies emerging, “we’ve never had more exciting innovation in wireless medicine. It’s extraordinary,” Topol said at a recent conference. In a later interview, he added that wireless sensing could transform how many diseases are treated. “Someday, this will give the ability to transform one’s home into an [intensive-care unit], with continuous vital-sign measurements. There is a lot going on here, and there is the potential that it will transform health care.”