How many times has this happened to you: You're sitting in freeway traffic or loading groceries into the station wagon at Safeway when you suddenly have a heart attack and die. And the only reason you wind up in an icy drawer at the coroner's office is because paramedics couldn't reach you in time to zap you with their fancy electric paddles. Well, now you need never succumb to a coronary again...

So begins the advertising campaign for Wal-Mart's new $29 heart attack resuscitation kit, the D-Fibrolator 7000. Available in four colors, the portable gadget costs thousands less than rival brands and has electrified the home defibrillator market.

Even Vice President Dick Cheney is rumored to carry one of the lightweight devices on hunting trips.

But a six-month Times investigation has discovered that the so-called defibrillator might be nothing more than a cleverly repackaged set of car jumper cables manufactured in China.

Wal-Mart officials declined to comment on the product's design, saying it was a trade secret. Attempts to analyze the defibrillator's effectiveness were also unsuccessful. The Times left numerous messages for cardiac specialists at UCLA, but a campus spokesman said the doctors were too busy reviewing celebrity medical records to comment.