What are two factors that lead to Mr. Pignati's death?

When John and
Lorraine first meet Mr. Pignati, his wife is dead, but he keeps himself busy by going to the zoo
every day to see a baboon named Bobo. He calls Bobo his best friend. As their relationship
with Mr. Pignati grows, it seems as if extended life also grows inside of the Pigman. Now the
old man has Bobo and John and Lorraine to keep him from suffering complete loneliness.

Mr. Pignati suffers a heart attack in chapter ten as he is playing tag with the kids
in his home one night. As a result, he winds up in the...