9 Letter word, if you lose it you die, What is the word?

It is a 9 letter word – 123456789.

If you lose it, you die,

If you have 234, you can 1234.

56 is one type of disease.

89 indicates exact location & time

2 & 7 are same letter

3 & 8 are same letter

5 & 9 are same letter guess the word !!

?????

HEARTBEAT