A recent study in the medical journal The Lancet found that this wireless monitoring device, inserted in an artery between the heart and lungs, reduced the number of additional hospitalizations by 39 percent.

Doctors now rely on indicators like body weight and blood pressure to make adjustments in a heart disease patient’s medication. But that approach often detects problems too late to avoid additional hospitalization. The sensor can transmit precise data from inside a pulmonary artery, and before other symptoms appear.

“Heart failure is most common cause of hospitalization for older adults,” says Dr. William Abraham, an Ohio State University researcher who helped lead the study. “We need better strategies to keep people out of hospital. Unfortunately our current tools haven’t proven effective.”

Nearly six million Americans have heart failure each year, according to the U.S. Centers for Disease Control and Prevention, costing some $39.2 billion in annual medical bills and lost productivity. The most common causes of heart failure are coronary artery disease, high blood pressure and diabetes.

The sensor allows doctors to measure fluid and pressure levels within the heart and lungs, Abraham says.

To put it crudely, it’s like the monitor in you car that warms when tire pressure gets too low.

“This is a real game-changer. It gives information on patients we’ve never been able to get before in easily used fashion.”

The sensor has no battery and no moving parts. The patient lies on a specially-equipped pillow that transmits a harmless radio signal to power the device and get the pressure reading.

The sensor was developed by an Atlanta-based company called CardioMEMS, which paid for the study. The experimental device still must be approved by the Food and Drug Administration.

If the sensor goes into general use, Abraham estimates it will cost about $15,000 for the device and the implant procedure. A single hospitalization for heart failure can cost $8,000 to $16,000, he says. “So averting one hospitalization potentially makes up whole cost of implanting device,” Abraham says.

In the study, 550 patients from 64 centers across the United States were given the sensor implant and told to take readings once a day, which were sent to physicians by computer. One group took medication prescribed by doctors using the implant data. The control group was advised by doctors using weight and blood pressure as indicators. Over six months, the first group had 39 percent fewer return trips to the hospital.