Dr. Sherwin Nuland, medicine’s best-known historian, was visiting with Dr. Michael DeBakey three years ago when the then-96-year-old surgeon left the room to attend to some business.

Taking advantage of the moment to tour the room’s extensive collection of memorabilia — the honors, photographs and mementos from an illustrative career that spanned eight decades — Nuland stopped to reflect on two antiquarian charts of the history of medicine.

“As I studied the charts, it occurred to me that no face on them was any more important in the history of medicine than DeBakey himself,” said Nuland, a retired surgeon at the Yale University School of Medicine and author of Doctors: The Biography of Medicine. “I can’t think of anyone who’s made more of a contribution to the field of medicine.”

Michael Ellis DeBakey — internationally acclaimed as the father of modern cardiovascular surgery and considered by many to be the greatest surgeon ever — died Friday night at The Methodist Hospital in Houston. He was 99.

Methodist officials said DeBakey died of natural causes. He was taken to the hospital after his wife, Katrin, called 911, and he was pronounced dead shortly after arriving, said Dr. Marc Boom, executive vice president of Methodist.