WASHINGTON (AP) - The government has approved a pacemaker outfitted with a tiny transmitter that can tell your doctor how your heart is doing - the first medical implant capable of such real-time monitoring.

The Biotronik Home Monitoring System essentially provides a house call any time of day without doctor or patient taking any special steps. It's the first in an expected wave of medical devices that will let doctors track the chronically ill day-by-day in an effort to keep their conditions from worsening between office visits.

"This is an exciting development," Dr. Stuart Portnoy of the Food and Drug Administration said of the Biotronik device, which won FDA approval Thursday.

Pacemakers contain recorders that continually track heartbeat, how often the devices zap the heart back into rhythm, and other important information. Instead of requiring a doctor visit to download all that recorded data, manufacturer Biotronik Inc. inserted a tiny transmitter inside a pacemaker to automatically send the data to a cell phone-like device the patient keeps nearby.

That gadget then makes a cellular phone call to a Biotronik central computer that downloads the data wirelessly, and faxes the medical record straight to the doctor's office. It all happens automatically - day or night - without the patient even knowing.

That means instead of a doctor checking a patient's condition once every six months, he or she can customize the pacemaker monitor to check it weekly or even daily. If the heartbeat's too sluggish or the pacemaker isn't zapping at the right voltage, the patient can be urged to come in for treatment before the problem worsens.

Patients' only restriction: The receiver, that phone-like gadget, must be kept within 6 feet of the body to receive transmissions. Patients can wear the receiver on a belt or carry it in a purse - or, as Biotronik suggests, doctors can program the transmission to occur at 2 a.m. every day and patients simply can keep the receiver by their bed.

An added feature: If patients feel bad, they can hold a special magnet in front of the chest that will signal the pacemaker to transmit right away, so doctors can see even more quickly if the heart's condition is worsening, said Mark Johnson, Biotronik's manager for the monitoring system.

The FDA approved the system based on studies proving the pacemaker could reliably transmit data without electronic interference. But how well will it work in real life?

To answer that question, Biotronik is restricting the first few months of sales to 100 patients at 10 medical centers. There, doctors led by Stanford University researcher Dr. Sung Chun will study how easy the monitoring system is to work and how useful it is, before wider sales begin.

Participating sites include: Stanford; Chanwell Cardiovascular Clinics in San Jose, Calif.; Aultman Hospital in Canton, Ohio; University Hospitals of Cleveland; St. John's Hospital in Detroit; St. Mary's Medical Center in Saginaw, Mich.; Providence Medical Centers in Yakima and Everett, Wash.; Columbia Hospitals Medical Center in Aurora, Colo.; and Hackensack, N.J., Medical Center.

The pacemaker and monitor - including Biotronik-provided digital service for the cellular phone calls - will cost about $5,000, comparable to standard pacemakers, Johnson said.

The device should prove a cost-effective way to improve care, said American Heart Association spokesman Dr. Timothy Gardner, chief of cardiothoracic surgery at the University of Pennsylvania.

But because it provides limited information, it's just a first step in the hot new field of remote health monitoring, he said.

"The next steps of getting actual full physiological monitoring may be more difficult, but I'm sure we'll reach a point where that kind of information being transmitted to a doctor's office will be just like the telemetry we do on patients when they're in the hospital," Gardner said.

For now, the device is supposed to supplement, not replace, regular doctor visits, FDA's Portnoy cautioned. Pacemaker recipients typically see both a cardiologist and a pacemaker specialist, but if ongoing studies prove the monitoring system works well, visits to the latter specialist may not be needed as often.

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