My heart is beating very hard.

My heart is pounding, so I can write an exaggerated sentence as follows:

1, my heart is beating so hard that I am about to jump out of my chest.

My heart is beating so hard that my chest is almost cracked.

My heart is beating so hard that it almost jumps out of my throat.

My heart is beating so hard that it seems that there is a huge drum beating.

My heart was beating so hard that I jumped into my throat.