To the long list of objects vulnerable to attack by computer hackers, add the human heart.

The threat seems largely theoretical. But a team of computer security researchers plans to report Wednesday that it had been able to gain wireless access to a combination heart defibrillator and pacemaker.

They were able to reprogram it to shut down and to deliver jolts of electricity that would potentially be fatal  if the device had been in a person. In this case, the researcher were hacking into a device in a laboratory.

The researchers said they had also been able to glean personal patient data by eavesdropping on signals from the tiny wireless radio that Medtronic, the device’s maker, had embedded in the implant as a way to let doctors monitor and adjust it without surgery.

The report, to published at www.secure-medicine.org, makes clear that the hundreds of thousands of people in this country with implanted defibrillators or pacemakers to regulate their damaged hearts  they include Vice President Dick Cheney  have no need yet to fear hackers. The experiment required more than $30,000 worth of lab equipment and a sustained effort by a team of specialists from the University of Washington and the University of Massachusetts to interpret the data gathered from the implant’s signals. And the device the researchers tested, a combination defibrillator and pacemaker called the Maximo, was placed within two inches of the test gear.