"We had to urgently open his chest and place him on the bypass machine without really being ready for it yet," said Dr. Olaf Reinhartz, lead surgeon on Wylie-Modro's operation.
More than 10 hours later, the operation to give the Gunn High School senior a new heart was successfully concluded.
On its own, the operation would have been dramatic enough. But it was only one of three heart transplants that took place over a course of three days at Lucile Packard Children's Hospital.
"Normally we do 15 or 16 transplants a year," said Dr. Daniel Bernstein, pediatric cardiologist.
Reinhartz was lead surgeon for all three operations, each of which took 10 to 12 hours to perform. He said Wylie-Modro's case was the toughest because he was in the most unstable condition coming into the operation.
"He was one of these cases where you're in there constantly concerned about the patient," he said. "And you're not sure whether you can actually save the patient. And I was very happy to see that he woke up."
Wylie-Modro was born with single ventricle physiology, a congenital heart disease. Whereas normal hearts have two separate chambers to pump blood to the lungs and body, his heart had only one chamber.
The heart transplant was not the end of his ordeal. His mom, Sheron Wylie-Modro, said in the days after the operation, doctors discovered and removed a blood clot from his brain.
"That new heart actually carried him through quite a major brain hemorrhage operation," she said.
"We're certainly very, very grateful to the donor," William Wylie-Modro said, the emotion apparent in his voice, "and grateful for any other potential donors."
Wylie-Modro will graduate this month with honors from Gunn. He has also received a scholarship to help pay for his tuition at the University of California, San Diego, where he plans on studying aerospace engineering. His admission has been deferred for a year to give him time to recover.
Bernstein said Wylie-Modro will be in the hospital for at least two more weeks.
He will turn 18 in June and said after his release he and his family may visit England, where he has family ties.
He said he plans on "going to a pub and buying my dad a pint," explaining the British tradition of buying one's father a pint upon turning 18.
Amanda Sechrest and James Spencer also received heart transplants, with their operations occurring on May 3 and 5, respectively.
Sechrest, who also received a liver transplant, is projected to stay in the hospital for a couple more weeks. She is currently studying education at St. Mary's College.
"It's a roller coaster," she said of her experience with her congenital heart disease and the operations. "But I finally feel like the roller coaster's coming to an end."
Spencer was released from the hospital nine days after his operation and said he looks forward to "getting back on my feet, and just getting back to where I was at."
He plans on continuing his studies at Santa Rosa Junior College, where he plans on majoring in kinesiology, with a minor in physical education.
His mother, Kim Spencer, expressed her gratitude to the donor family and said her family planned on making contact with them some time in the future.
"Hopefully it's some comfort to them that a portion of their loved one lives on," she said.
Kim Spencer and Sheron Wylie-Modro both praised the doctors and medical staff at the hospital as well.
"We're so lucky that we live in the area where we do, to be able to come here to Stanford," Kim Spencer said.
Dr. Reinhartz credited the size and skill of the medical team with making the multiple operations go relatively smoothly.
"Despite this sounding like a big marathon effort, it actually went pretty easy," he said. "And that is because we have so many people involved in the process, and everybody knows what he's doing."
Reinhartz said it was "fun" to do the three operations in a row and see successful outcomes.
"You get a lot of satisfaction out of my job," he said, "and that's why I consider it one of the greatest jobs you can do."
While Wylie-Modro was not well enough to leave his hospital room, Bernstein stood in the lobby with Spencer and Sechrest in front of a group of reporters and urged members of the public to sign their donor cards.
"We wouldn't have these two young people if it weren't for some very courageous and very special families," he said.