Dr. Leonard L. Bailey, the surgeon who made medical history and drew criticism for transplanting a baboon heart into a human baby at Loma Linda University Medical Center, said he may repeat the operation this year. Bailey says he is ready to proceed with a new animal-to-human transplant after more than two years of research to determine what went wrong with Baby Fae, who died 20 days after surgery. "It's pure speculation," he said in an interview published in the Riverside Press-Enterprise, "but I would imagine we'll be doing another cross-species procedure . . . sometime this year." He stressed that such an operation would be a bridge, with the baboon heart used only until a suitable human heart could be located for a transplant.