Chest pain, shortness of breath, indigestion, backache, nausea: they could be symptoms of a myocardial infarction -- or they could mean you have the flu. Many people are reluctant to wake their doctor at 1:00 a.m. over a case of indigestion -- but if they're really in the throes of a heart attack, waiting it out is the worst possible thing to do.

Enter EKGuard, a portable gadget and subscription service now available for the first time in the United States. EKGuard provides clients with a handheld electrocardiogram (EKG) monitor and a 24-hour call center staffed by cardiac specialists. Their goal: to drastically reduce the time between the onset of a heart attack and a patient's arrival at the hospital.

"The biggest problem when it comes to heart disease is that people aren't acting fast enough," says Jay Lichtenstein, EKGuard's president and CEO. "Typically, there's about four to six hours between when people feel symptoms and when they seek help. But after two hours, a person's chances of dying double -- her heart muscle suffers permanent damage because it's not getting oxygen." And the greater the damage, the lower the chances of survival.

Currently, EKGuard is available only in New York, Connecticut, and New Jersey. All calls are channeled to a center in mid-town Manhattan, where the phones are answered by cardiac doctors, nurses, and EMTs. When a customer signs up for EKGuard, the company sends a handheld EKG monitor. They also take a customer's medical history, contact his or her doctor and cardiologist, and explain how they should take a baseline EKG, for reference by cardiac specialists.

The portable monitor has three wires; placed in the right spots on the body, they record data from 12 different leads, like a standard hospital or ambulance EKG. When collected, the data build a picture of how efficiently electrical impulses are traveling through the heart. To transmit the EKG readings to the call center, the device translates the information into sound and plays it over a phone line to a computerized receiving station, where it is reconfigured into an EKG chart that can be analyzed for irregularities.

The technology itself isn't new: The device EKGuard uses (manufactured by an Israeli company, Aerotel Medical Systems) was approved by the U.S. Food and Drug Administration in 2000. But legal and practical issues stalled the development of the call-center service for years. Most doctors, for instance, are licensed solely in the state where they practice, so the call center had to hire medical staff who could advise clients from each state where the company does business.