heart in one's mouth, have one's

have (one's) heart in (one's) mouth

To feel very nervous or anxious. I had my heart in my mouth as I waited for the ambulance to arrive.
See also: have, heart, mouth
Farlex Dictionary of Idioms.

heart in one's mouth, have one's

Be extremely frightened or anxious, as in When the plane was about to take off, my heart was in my mouth. This usage alludes to the heart beating so violently that it appears to leap upward. [Mid-1500s]
See also: have, heart
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • have heart in mouth
  • have your heart in your mouth
  • have (one's) heart in (one's) mouth
  • (one's) heart is in (one's) boots
  • lose heart to
  • lose one's hear to
  • lose your heart
  • lose (one's) heart to (someone)
  • have a heart
  • lose heart