The author, in lines 349-352, when the character Annie talks about her feelings towards the words I shall never see this again, creates a movement of heart pumping blood as he describes the heart swelling and quickly shriveling again. Therefore, the reader realizes that Annie's emotions were very strong and genuine, causing her heart to beat fast. Also, the description of her heart beating creates the poetic image of a sudden change in her emotions: once she was glad, and suddenly she felt stabbed. The character's reaction seems like something so inevitable (just like the heartbeat) that it took her over. The image created by the author with those words made her emotions change from a deep happiness to an intense pain very fast. So, the author's word choice is connected to the understanding and perceiving of that change.
