扑通扑通

1. thump-thump, bang-bang, pit-a-pat, pitapat, pitter-patter

adverb taking the 'to' particle adverb (fukushi) onomatopoeic or mimetic word

(心脏)跳动得很快，悸动

2. to beat fast (of one's heart), to throb, to pound, to palpitate

noun or participle which takes the aux. verb suru onomatopoeic or mimetic word