Meaning of "heart"

[All Potted Out]

Dear Teachers,

What I read was:

"The woman there on the floor is convulsing, thought Bianca, and her heart moved cautiously."

Does this heart refer to that organ we have in our chest? But, how can one's heart "move cautiously"? Does it mean something like "beats slowly"? And, whose heart it is? Bianca or the woman on the floor?

[Pamela]

I think heart is used in the figurative sense. Are your punctuation marks correct? I think that Bianca's heart moved cautiously because of fear caused by lookind at the woman being in convulsion. More context the better, all potted out.