what is the most dangerous operation that has happened

Question: what is the most dangerous operation that has happened
- Keywords:
  danger,
  experiment,
  operation
Asked by jakef98 to Rika on 23 Jun 2011.
- Chandrika Nair answered on 23 Jun 2011:
  
  I think heart surgery and brain surgery are problably the hardest. I’d say the hardest operation is open heart transplant, the first one was done in 1967. That must have been challenging!

Question: what is the most dangerous operation that has happened