Hearing (akouōn). Present active participle of akouō, while hearing.
Fell down (pesōn). Second aorist active participle of piptō, fell all of a sudden while listening.
Gave up the ghost (exepsuxen). First aorist active indicative of ekpsuchō, late verb in lxx and Hippocrates, to breathe out, to expire. In the N.T. only here, Act 5:10; Act 12:23. It is needless to blame Peter for the death of Ananias. He had brought the end upon himself. It was the judgment of God. Physically the nervous shock could have caused the collapse.