Thanks to the mircle of electronics and the payment of $3 million to General Electric, your heartbeat now can be transmitted from Frostburg to Ocean City and back again almost as fast as you can say "my chest hurts."

And the ambulance attendant doing the transmitting can communicate directly with any one of 5,000 physicians, 12,000 nurses, 45 hospitals, 349 other ambulances, and three helicopter services in each of Maryland's 23 counties and Baltimore city.

While most states have citywide or countywide emergency medical communications systems, the radio and telephone network unveiled here yesterday by officials of the Maryland Institute for Emergency Medical Services is the first in the nation to link the entire state's emergency medical care.

The workings of the communications system con be described much the way the body is described in the old song about the anklebone being connected to the shinbone.

Say you are suffering chest pains at your home in Gaithersburg. When the mobile cardiac care unit arrives, a member of its crew can attach a portable machine to take an electrocardiogram.

The machine reads and records the millivolts of electricity being given off by your heart. The ambulance crew then uses a walkie-talkie to relay that amplified electronic pattern to the transmitter in the ambulance, which can in turn relay it to, for example, Suburban Hospital in Bethesda, where a cardiologist could interpret the electronic squiggles and give instructions to the emergency medical technicians on the scene.

The system also gives the EMTs (emergency medical technician) the capability of relaying that signal to the central communications center at Baltimore's Mount Sinai Hospital, which would then relay it by special telephone line to one of four special cardiac referral centers in the state, all in a matter of moments.

The center at Mount Sinai, with its flashing lights and electronic map of the state indicating which ambulances are on call where, looks a bit like something out of the movie "Star Wars."

Some of the portable units carried by the ambulances, however, look precisely like the equipment seen on the television show "Emergency, and they are.

The Sinai center serves as communications headquarters for Baltimore city and the five contiguous counties, and has been used to test the concept of the statewide system.

According to Dr. John Stafford, director of EMS systems programs for the Maryland Institute for Emergency Medical Services, 20 percent of the "cardiac standstill cases" in the Baltimore area in the last six months - cases in which the patient had no hearbeat at all when the ambulance arrived - have been saved. Without the communications system, Stafford said, those patients would have died. add three - EMERGENCY - AR.

In addition to the center at Mount Sinai there is also a communications center at the Maryland Institute for Emergency Medicine, more commonly known as the Shock Trauma Unit.

The facilities there, which are much less fancy looking than those at Mount Sinai, serve primarily as a communications center for the Maryland State Police, U.S. Park Police and U.S. Army Med-Evac helicopters that participate in the Maryland emergency medical services system.

The Shock Trauma unit also provides the link in the system through which ambulance or helicopter crews, or physicians at hospitals in all areas of the state, can communicate directly with the unit's specialists for help in assessing and stabilizing severely injured patients.