Tumultuously

Tumultuously– Adverb

Definition:  loud, excited, emotional, involving a lot of violence, confusion or disorder (http://www.merriam-webster.com/dictionary/tumultuous)

The Story of an Hour by Kate Chopin

At the beginning of tenth paragraph –   “Now her bosom rose and fell tumultuously”.

As used in this context, tumultuous would be best defined as a violent agitation up of mind or feelings or a violent outburst.

In this sentence tumultuously seems to indicate that Mrs. Mallard’s heart is pounding so hard that her chest is visibly beating.