He had a failing heart. Towards the end he had this prefabricated valve put in it.
10 seconds sound clip from the Planet of the Apes (1968) movie soundboard.
You can hear this line at 01:37:27 in the Blu-ray version of the movie.
Quote context
[...]
- Keep digging. You'll find evidence of the master of this house - an ape.
- You say these things were found at the same level as that doll?
- Whoever owned him must have been in pretty bad shape. He wore false teeth and eyeglasses.
- He had a failing heart. Towards the end he had this prefabricated valve put in it.
- He was a weak, fragile animal.
- But he was here before you, and he was better than you are.
[...]