What are the chances of this happening?

A short story form Northern Ireland this week.
A guy is watching his Uncle lying seriously ill in a hospital bed. His Uncle will die without a heart transplant. The Nephew decides to get an organ donor card. A fortnight later the Uncle gets a heart transplant. Where’s the heart from? His nephew, killed in a stabbing, had his heart used for his uncle’s transplant.
Can’t impagine what the family’s going through, one member dying so another can live. What are the chances of this happening?

The chances are 1 to 10 on the PAX TV Network.

Nice story, though.