With an artificial heart pumping in his chest, William J. Schroeder wept tonight as he thanked God for his past two weeks of life and the future the device may give him.

His voice quavering and his eyes filling with tears, Schroeder said, "I have a real new purpose in life, and that purpose is just to be with God, to feel like he is No. 1 that saved me."

His wife, Margaret, leaned forward and wiped the tears from her husband's cheek with a crumpled tissue.

"That's my big purpose right here," he said. "We've been married 32 years, and I wouldn't take anything in the world for her."

Referring to the grim prognosis shortly before his historic surgery Nov. 25, Schroeder said, "I feel like I've got something to look forward to. Forty days -- I wouldn't even have had Christmas."

The first artificial-heart recipient, Barney B. Clark, was never well enough to speak to reporters. Three months after his implant in December 1983 at the University of Utah Medical Center, Clark was interviewed for 2 1/2 minutes by Dr. William C. DeVries, the same surgeon who operated on Schroeder at Humana Hospital-Audubon in Louisville last month. Clark died three weeks later.

Two weeks to the day after his failing heart was replaced with a metal-and-plastic pump, Schroeder welcomed two pool reporters into his hospital room and invited each to put a hand on his chest. In a videotape last week he had seemed buoyant, but tonight he simply exuded quiet confidence in the machinery keeping him alive.

He said he hopes his future will include the birth of a grandchild, a son's wedding and the purchase of a van with a lift so he can go fishing.

"I don't see any reason why this thing won't last 10 years," he said.

Over the steady thump of the portable, 11-pound power pack that pumped his blood throughout the 32-minute interview, Schroeder shook his head when asked about recent criticism of the artificial heart project from the American Medical Association.

Speaking of his rapidly deteriorating health before his implant, Schroeder said emphatically, "Why should you prolong something when you know you've got a chance to make it? I know I've got a chance to make it. I've taken chances all my life, and I believe in them. I was gung-ho on this thing."

Asked what advice he would give to someone contemplating an artificial heart implant, Schroeder replied, "I would probably tell him if he'd had open heart surgery it wouldn't be any different. The only difference is that you got two tubes coming out your side."

Schroeder noted that he had been healthier before the operation than Clark, who lived 112 days with the artificial heart and was plagued by longstanding lung and kidney problems and periods of depression. Less than two weeks after his implant, Clark suffered seizures, and doctors have sought to avoid that with Schroeder by carefully calibrating his heart rate.

As for the copious medical reports on Schroeder's condition issued by officials from Humana Inc., the for-profit hospital corporation that has agreed to underwrite more such operations, Schroeder said he was happy to contribute to greater public awareness of the project.

"Let people become interested in it," he said. "Let them pick it up from there. They're still going to make their own choosing . . . . I don't care if they release every bit of information they've got on me."

Schroeder said he doesn't worry about the possibility of his life-sustaining machine breaking down, citing the numerous backup systems.

And he said that he doesn't mind the prospect of spending the rest of his life supported by a machine.

There was never any question in his mind, once he knew that the artificial heart would be his only hope, Schroeder said. Toward the end of the interview, his eyes filled with tears as he remembered his discussion with his wife, six children and family doctors about the artificial heart.

"I laid it on the line . . . I said, 'How many days do I have?' and they told me. So I said, 'Okay.' . . . I said, 'You kids got any problems?' So they said, 'No.' So I said, 'Go with it,' " he recalled, his voice choking again with emotion. "So we did."

Last Friday, Schroeder left his intensive-care room for the first time after surgery, riding in a wheelchair to the hospital's radiology department for tests. His condition was upgraded then from serious to satisfactory, and he was moved from his intensive-care room to transitional care, where tonight's interview took place about 8 o'clock.