Wireless House Calls

Wedding wireless telemetry to cardiac pacemaking technology, Medtronic Inc. has won FDA approval for two implantable devices that monitor a patient's heart and send diagnostic information over a wireless local network and landline Internet connection to physicians.

The two new devices are the first implantable cardic regulators that use Medtronic's Conexus wireless system, which runs over the 402-405MHz frequency, a band known as the Medical Implant Communications Service.

The Concerto and Virtuoso are defibrillators that use small electrical shocks to restore the heart's normal rhythms in episodes of fibrillation or arrhythmia. Both emit wireless signals to a modem in the patient's home that in turn uses a dial-up Internet connection to send patient information to a doctor or a hospital.

In development for more than a decade by Medtronic, the world's largest medical device maker, the system will help save the lives of patients with congestive heart failure, says Dr. George Crossley, chief of electrophysiology at Baptist Hosptial in Nashville, who spearheaded clinical trials of the devices.

"There are lots of convenience aspects to this, in the clinic and in the operating room," says Crossley. "But the enormous value is in remote monitoring at home, so that the doctor can get this information before the patient even realizes there's a problem. It's an early-warning way to deal with heart failure, rather than trying to solve the problem in the hospital three months later."

One element of the system, which will allow doctors to detect dangerous build-ups of fluid around the heart -- often a signal of impending heart failure -- still awaits a full-blown clinical trial to be carried out over the next year to 18 months. That function has already been approved for use in Europe.

A major part of the development process of the Concerto and Virtuoso devices was finding a suitable frequency. Many medical devices in use today operate of the 900MHz frequency, which can be congested in settings like hospital. The 402-405MHz band is used only by the new cardiac devices and by weather balloons aloft high in Earth's atmosphere.

Medtronic expects the new devices to be available by mid-June.

— Richard Martin, Senior Editor, Unstrung