Washington ? Draw a vial of blood from someone with advanced heart failure. Zap the blood with heat and other stresses, then inject it back in hopes the altered blood cells will trick the patient’s immune system into fighting the heart-destroying disease.

Dr. James Young was highly skeptical that the pilot experiment would work, but desperate patients were lining up. So he tried it, and to his surprise the monthly treatment kept a significant number out of the hospital and even seemed to delay death.

Now Young, heart-failure chief at The Cleveland Clinic, is about to study 2,000 more patients to prove if the therapy really works. It’s a dramatically different approach to fighting an intractable killer, and one that doctors are watching closely because many other attempted treatments have recently failed.

“Intrigued’s a good way to put it,” said Dr. Wilson Colucci, cardiovascular chief at Boston University Medical Center, who works with the American Heart Assn. “This comes along at a time when specialists are wondering what else we can offer.”

Almost 5 million Americans have congestive heart failure. Their hearts are weakened by age, damage from a survived heart attack or some other disease and thus can’t pump strongly. Eventually patients are pressed even to walk across a room. Fluid seeps into their lungs and blocks breathing.

When medications fail, they have few options. Just half survive five years.

Attempts to find new medications have largely stalled. The latest therapy — special pacemakers that make damaged hearts pump more forcefully — is helping many patients feel better and stay more active. But those devices don’t attack heart failure’s underlying causes, and there’s no evidence yet that they lengthen life.

Enter the blood-zapper, made by Canada’s Vasogen Inc. Called immune modulation therapy, it’s based on a theory that heart failure is fueled when the immune system goes awry and causes too much inflammation, much as inflammation-run-amok also causes arthritis and even heart attacks.

That theory took a hit in 1999 when two drugs that target the inflammatory molecule that is considered heart failure’s main culprit failed to work. Stunned scientists speculated that many other inflammatory molecules must play roles, too. Hence Vasogen’s immune modulation therapy attempts to broadly block inflammation.

A small vial of blood is drawn from a heart-failure patient and put into a machine that stresses the cells by heating them to 108 degrees, zapping them with ultraviolet light and mixing in a little ozone gas.

Injected back into the body, the stressed cells soon commit suicide. The hope, Young explains, is that the little burst of unexpected cell death will signal the immune system to suppress inflammation, thus temporarily halting heart damage.

In a 73-person pilot study, only one death occurred among patients given six months of Vasogen treatment compared with seven deaths among patients given dummy shots. The blood zapper cut hospitalizations almost in half, too.

“Your energy level would increase within days,” recalled Cindy Markowitz, 56, of Youngstown, Ohio, a teacher who missed fewer days of school during the pilot study and desperately sought out another experimental therapy when the trial ended. “I really started sliding down again after I went off the Vasogen, and I never thought that was fair. If they give you something that works, they shouldn’t make you stop taking it.”

This spring, 2,000 more patients will get either 15 months of the experimental treatment or dummy shots when Young, along with Houston’s Baylor College of Medicine and the University of Montreal, studies whether immune modulation therapy really works, and how well.

The pilot study was promising but very small, cautions American Heart Assn. spokesman Dr. Clyde Yancy. And given previous anti-inflammatory failures, the new experiment may be the last chance to prove inflammation is a cause, not a byproduct, of heart failure, he says.

More important, Yancy stresses, is that between a third and a half of heart-failure patients today don’t take medications already proved to save lives, a combination of pills called ACE inhibitors and beta blockers. More advanced patients are supposed to consider a third pill, called spironolactone.

“We definitely need to push the envelope, identify new strategies,” said Yancy, a cardiologist at the University of Texas Southwestern Medical Center. “But for the ordinary individual that is affected with heart failure, the first, second and third steps must be to get people on … best available therapy.”