someone's heart is in their mouth
US /ˈsʌm.wʌnz hɑːrt ɪz ɪn ðer maʊθ/
UK /ˈsʌm.wʌnz hɑːrt ɪz ɪn ðer maʊθ/

1.
avere il cuore in gola, sentirsi molto spaventato
to feel very nervous or frightened
:
•
When the roller coaster started, my heart was in my mouth.
Quando le montagne russe sono partite, avevo il cuore in gola.
•
Her heart was in her mouth as she waited for the exam results.
Aveva il cuore in gola mentre aspettava i risultati dell'esame.