Transcript for Surgeons race against time to transplant lungs in dad who survived COVID-19: Part 2
Janssen may be able to help. Leo Castillo and his family are desperate for more moments like these. But the next six hours will forever change their fate. Performing a double lung transplant on a covid patient is very complex. We just discovered his heart is really weak and struggling because of the lung failure. Get that second circuit and we'll connect the valve and everything -- Growing up in India, I wanted to be an air force pilot. But we had a family trauma that was personal, and that turned me to medicine. You lost a brother, I understand? I was 11, he was 9. He had a traumatic brain injury. And you're all in a state of shock. But there were a number of talented physicians and surgeons who kept him alive for two or three days. It gave us time, a little bit of hope. That he may survive. For me as his older brother, it gave me time to apologize for some of the big brother things I may have done to him. Do you think he would be proud of you today? I hope so. Ready? Going slow and deliberate because these patients tend to have a lot of bleeding. You almost never see this severe scar tissue. Reporter: What you're about to see is graphic. Back at the donor hospital, Leo's new lungs are removed from the deceased donor. They have to go into Leo's body within six hours or they'll start to deteriorate. These are Leo's lungs, yeah. They're taking off now. Reporter: With the new lungs en route, the old ones are creating major problems far worse than expected. I don't know what the Is going on. Did you ever worry that you'd lose him? Reporter: As Dr. Barat pushes forward, the donor lungs arrive. The clock is ticking. They now have just 3 1/2 hours before the lungs could go south. As the team works to remove Leo's old left lung, he starts to bleed significantly. Can you pack that? That's very stressful, man. He might die on the Table. Reporter: Despite the massive blood loss, doctors are able to remove the lung. Okay, can I get the left lung? Reporter: The difference between the new left lung and Leo's old lung is staggering. See how pink and nice these lungs look? This is what we are about to implant. Okay. Reporter: Leo's new left lung helps to stabilize his body. As the surgical team now hurries to remove and replace his right lung. Swab the right side, please. He's very critical right now. We've been able to expand the lungs. This was by far the worst, most difficult dissection. This is terrible-looking lungs, my god. It's like a bomb went on. We're about to start the right lung implant. As soon as the second lung went in, everything started to get better. His heart is contracting better. All the pleading stopped. Okay, go ahead, inflate this lung. Beautiful. Beautiful lung. What is that like to you, to see the lungs inflate in the new recipient? It literally is so stunning to see them inflate and deflate, see the patients pink up, it's one of the most miraculous that was one of the best feelings to say, okay, we did this, and he's going to be okay now. Thank you. This was not easy, man. Thank you for getting him through. Reporter: Four days after Leo's surgery, a special visit from a new friend, Myra Ramirez, the first post-covid patient to receive new lungs. What's it like watching Leo struggle back? You must see yourself in him. It's really sad. He's going through a lot. I hope he keeps his mind healthy and positive. It takes a lot of mental strength to be able to go through this. Reporter: It takes grit to learn to walk again. But Leo still has miles to go in his rehab. The biggest fear? Chronic rejection. 40% of patients can experience that in five years. The good news about that is only 10% to 15% experience the most severe form of chronic rejection, to the point they need a retransplant. Reporter: Nearly four months after the transplant, he's more positive than ever. How much do you want to go and be with your wife and beautiful daughters again? When he comes back home, I'll say I love you and hug him really tight, because I miss him so much. So many emotions, I can't explain it. Reporter: Leo will spend six more months in Chicago to remain under doctor barat's care. Oh, look at that, llo, how are you doing? Reporter: In the meantime, Dr. Barat makes good on that pretransplant promise. You said you want to eat a hamburger when you get better, so here's a hamburger for you. Is it good? All right. I want to say thank you. You're the best. You are the best. And my lord is the number one, and you're the number two. You're a hero. And yeah, I appreciate you for that. Reporter: This singular life saved, among hundreds of thousands, providing endless reasons for hope. I make a new life because my life has started when I transplant. I started my life. I am happy. Every day congestion
This transcript has been automatically generated and may not be 100% accurate.