Seattle dentist Barney B. Clark spoke to the world today for the first time since he became history's first permanent artificial heart recipient. In a brief videotaped interview he appeared weak and short of breath, but pleased with the plastic and metal device keeping him alive.

Clark, who received his new heart three months ago today, said his recovery, marked by seizures, lung problems and a temporary malfunction of an artificial heart valve, "has been hard, but the heart itself has pumped right along, and I think it is doing well."

In the interview, taped Tuesday afternoon and released today, Dr. William C. DeVries, who implanted the heart, asked Clark what he would advise others considering an artificial heart implant. Clark replied, "Well, I would tell them that it's worth it if the alternative is they either die or they have it done."

During a news conference at the University of Utah Medical Center, DeVries and several other doctors said that Clark had made substantial improvement in the last 10 to 12 days, after several weeks in which his chronic lung problems and other physical ailments marred recovery.

DeVries said doctors and nurses particularly were encouraged that they had been able to take Clark off an artificial respirator and tap the breathing tube inserted in his throat so that he can speak. A psychiatrist said her conversations with Clark, 61, indicated that the confusion and disorientation he experienced for several weeks after the operation were gone.

"I think he's climbing the mountain," said DeVries, noting that Clark has suffered no setbacks in the last two weeks. "He's not at the summit yet. He has a ways to go."

Using a university television crew, DeVries conducted the 2 1/2-minute interview about 5 p.m. Tuesday in a conference room 200 yards from Clark's private hospital room. Clark, who DeVries said is not ready for a full-scale news conference, is tethered permanently to an air-compressing device that operates the heart through two long hoses inserted through the abdomen. The device can be wheeled with Clark as he moves.

Clark, dressed in blue pajamas and a red dressing gown, spoke slowly during the interview and slurred some words. He paused occasionally to take in more air, and mentioned as his first impression of his experience "the breathing--your lack of air."

Dr. Lyle D. Joyce, another of Clark's physicians, said later that Clark's emphysema and other lung problems could not be cured, but that he would be able to breath easier once he built up his stamina and chest muscles with a regular exercise program.

The medical center released photographs of Clark pedaling a bicycle exerciser and standing up while holding on to a walker. Therapist John Durkin said Clark exercises twice a day and goes about six feet in the walker, with some pauses for breath.

Nurse Carolyn Wiggins said Clark would have appeared more lively if the interview had been conducted in the morning. She said he talks often and sometimes has to be told to stop at night so that he can sleep. As a sign of his continued sense of humor, she mentioned that he recently received a plaque from a Seattle hospital and said, "That's very nice, and I didn't have to die to get it."

Psychiatrist Claudia Berenson said Clark had recovered from "acute brain syndrome," the disorientation that often accompanies serious heart, kidney and other diseases, and is now worrying about his exercises and his eventual release, which she said is a healthy sign.

DeVries said he could not predict when Clark would leave the hospital, but said it could be "a matter of weeks."