pit-a-pat
1. [ adverb ] as of footsteps
Synonyms: pitty-pat pitter-patter pitty-patty
Examples:

"he came running pit-a-pat down the hall"

2. [ adverb ] describing a rhythmic beating
Synonyms: pitty-pat pitter-patter pitty-patty
Examples:

"his heart went pit-a-pat"

Similar spelling:   pitty-pat
  pitty-patty