Bennett’s condition remained fragile all along. Still, after the operation, his new pig heart was squeezing powerfully and looking “super normal,” according to Griffith. Even a biopsy taken on day 34 showed no signs of the feared immune attack.
“It was quite amazing. You go talk to this gentleman and he’s got a pig heart. Literally, he has a pig heart,” Griffith said. The result was all but miraculous, yet Griffith acknowledged that the medical team was in anguish about whether they were doing the right thing.
In some ways, he says, they were like a “blind group of squirrels” scurrying to manage Bennett’s unprecedented condition as the days ticked by.
To keep tabs on the health of the pig heart, Griffith said, the team was constantly checking their patient with an array of cutting-edge blood tests. They used a DNA sequencer to scan his blood for floating fragments of pig genes—any increase would be a sign that heart cells were dying. Another novel test, developed by a company called Karius, screened Bennett’s blood for traces of hundreds of bacteria and viruses.
It was that test, run on a blood draw taken from Bennett 20 days after his surgery, that first returned “a little blip” indicating the presence of porcine cytomegalovirus, according to Griffith. But the levels were so low that the team thought the result could be in error, Griffith said, especially since the pigs were supposedly guaranteed free of the germ.
The doctors faced another problem—the special blood test was taking about 10 days to carry out. So they couldn’t yet know that inside Bennett’s new heart, the pig virus was starting to multiply fast and setting off what Griffith now believes was a possible “cytokine explosion”—a storm of immune-system molecules.
Even without up-to-the-minute tests, a serious problem became apparent around day 43 of the experiment. That day, Bennett woke up warm to the touch and breathing hard. “He looked really funky. Something happened to him. He looked infected,” said Griffith. “He lost his attention and wouldn’t talk to us.”
The doctors then faced a common problem in transplant medicine: how to fight infections while still keeping the patient’s immune system in check. And they were also handicapped by what they didn’t know. Not only were they still guessing at the true extent of the infection, but no one had ever treated a human for this particular pig virus, according to Griffith’s account.
