Vivien Thomas, 75, a Johns Hopkins University surgical technician who helped develop the famous "blue baby" operation, died Nov. 26 at his home here. The cause of death was not reported.

Mr. Thomas, who supervised Hopkins' surgical research laboratories for 35 years, was instrumental in developing procedures in animals that would later be applied to several heart defects in children and adults.

He worked with the surgeons, Drs. Alfred Blalock and Helen Taussig, to develop the "blue-baby" operation, which they first performed in 1944 while he offered suggestions and answered questions.

The blue-baby condition is "a congenital heart disease characterized by four disorders in the heart and large blood vessels," said Joann Rodgers, a Hopkins spokeswoman. "It is any of the four major disorders children are born with that create a lack of oxygenation so they literally look blue, instead of a healthy pink."

She said the most common disorder is one in which the aorta rises from the lower right side of the heart, instead of from the left, and the pulmonary artery, which provides blood to the lungs, comes from the lower left side of the heart instead of the right.

"The blue-baby operation actually was done to fix the holes and switch the vessels to the right place, so you got the proper mix of blood going in and out of the lungs," Rodgers said. "You have to remember that all heart surgery then was closed heart surgery."

Dr. Vincent Gott, a Hopkins cardiologist, said that Mr. Thomas "was almost legendary among cardiac surgeons. It is safe to say there is not a cardiac surgeon over 40 who doesn't know of him and his tremendous contributions to the specialty."

Another Hopkins heart surgeon, Dr. J. Alex Haller, said, "This is a great loss. Dr. Blalock once said that Vivien Thomas' hands were more important to him in the development of the blue-baby operation than his own -- and he meant it."

Mr. Thomas is survived by his wife, Clara S. Thomas; a brother, two daughters and three grandchildren.