It's not that often that someone has given the gift of a second chance at life. And right now nearly a 120000. Americans are waiting for just such a gift this selfless decision by one family. To... See More
It's not that often that someone has given the gift of a second chance at life. And right now nearly a 120000. Americans are waiting for just such a gift this selfless decision by one family. To donate organs and saved the life of a stranger. For all -- year now my fellow Nightline anchor Bill -- Has followed patients at the Mayo Clinic and the extraordinary transplant teams that bring them a chance for a new beginning tonight. Two of their stories from the agonizing wait to the vivid drama of the operating room. To the hope of -- future on their own terms. It's a Friday night at the Mayo Clinic. And a different kind of exciting Friday night out for the miners' family because nine months after sitting atop the waiting list each donor hearts is about touchdown. The Rochester Minnesota airport. Hearts bound for the chest of their nine year old son -- junior we're gonna do tonight. You -- what -- what why are you here. Or else that you're ready to go to our only. Narrowly ahead that's good -- constantly -- when he -- But before we can do that he needs the precious gift that's being transported in the red cooler. -- -- -- -- Walter is one of the nearly 120000. Americans waiting for a gift of this incredible sort -- too long. Liver or kidney that arrives because someone somewhere -- -- or checked a box giving gift of life to a complete stranger. When I was nineteen I was diagnosed with respected -- my house. Much less time congestive heart failure. A stranger like Jessica Daniels. Sweet -- -- three year old from -- She loves her job desperately wants to start family but knows that both will have to wait while she waits for a new heart and liver. And a -- for the return to the simple pleasures alive. I can't burn candles -- and I like to burn candles they smelled nice and they look nice to think taking bass I can't take a bath here. I just I'd take a big jacuzzi tub bath when I get out of here. But as -- -- speakers played the most -- Tom Cuddy solvable. Jessica. We'll just have to keep waiting. You don't really know when it's gonna happen. You can't predict. Years. You're living in the hospital. And you can think about you know the future but it's hard to make any plans. Advances in medical science have led to more patients being eligible for a life saving transplant. We also how the parents of Sarah Monahan took their quest public -- their -- -- the courts in order to get loans for their dying ten year old girl. But no matter how hard -- family fights or hopes. There are simply aren't enough donors. So eighteen people die every day waiting. But tonight. The wait is over for Coulter minor. Again -- this is the second time around for the Stanley since Jeff and Patti learn that their new little boy was born without the left side of his heart. That was back and asking him for him campers and Coulter had his first heart transplant at six weeks old so he is smaller than the other kids -- -- -- -- second grade class. And -- -- all the pent up energy of your average nine year old. And an encyclopedic. Knowledge of all things Star Wars. She finger sold well he also has his IV pole and -- -- in the expansive. Currently. And in recent years it became obvious that the donor heart might not last until age ten. So the family crossed fingers in the surgeons held out hope. And here it is a second second chance. The Mayo Clinic is known for its teen approach to medicine so this surgical team moves with seamless synchronicity. Timing -- surgery perfectly. Even the airport -- and I'm bypass or sizing the hard here now and we'll be taking shortly now if you are squeamish you might want to look away right about here but if you're fascinated by modern medicine. The holes as Coulter is the ailing heart is removed have a heart has been excised and keeps beating for a few moments in this surgical bull. This is hardly a novelty for the doctors so they remain focused on the contents of that red cooler. In the new heart slides -- As if -- been custom made for this little boy and a heart attack -- the perfect fit and I know -- -- a couple of days later I just look at it doing a pint sized jet -- ready for anything. This morning. Problem what's analyst at Rhode Island land there. It's on most are not located -- -- her eyes a little we can we can vote on this evidence you know she's -- -- -- -- -- yeah. Yeah that's right. -- On your scar for life gosh look at all the -- -- so half hour of vigilance and touching. Here's what I would do if -- -- you quarter. On the playground -- you show your scarred anybody wants to see it charge -- a quarter pound out. I check sent to -- in Galveston seawall warning dollars and. It's -- dead what would you say the family of the donor. Thank you. What are you can -- otherwise we went having here now. Down all Jessica Daniels and wrestles with the emotional tool of life at the top of the list. I'm praying for a new -- I am praying for another person to die and that bothers me all the time isn't my fault. That this person is going to die. Great but it's still -- none lines. To cheer up she sometimes takes Wilson for a stroll around the halls she named her ID -- After the volleyball. In the movie -- Because after four months of waiting in the hospital for heart and liver she often feels more room -- an island of pain and work. Keep me down and think -- -- certain added responsibility once. To live a life -- befitting of that gift. Almost -- -- he's going to be living for two people to know that I -- alive because. Someone else's. Heart is working for me. And -- kind of a beautiful thing inflate the marrying as to use souls I don't know. I don't know how it works yet. When we come back Jessica's true coolers -- But will these -- -- enough to save her life -- and -- -- -- second donor heart keep ticket.
This transcript has been automatically generated and may not be 100% accurate.