How does Mrs. Mallard's heart condition impact the way other characters interact with her?

The characters with whom we see Mrs. Mallard interact in the story are her sister and her husband's friend Richards.  We also are privy to Mrs. Mallard's thoughts about her relationship with her husband. With all three characters, there is evidence to show that Mrs. Mallard's heart condition has caused those around her to treat her far more carefully than a woman of normal health.

The very first sentence of the story tells us,

Knowing that Mrs. Mallard was afflicted with a heart trouble, great care was taken to break to her as gently as possible the news of her husband's death (para. 1). 

This sets the stage for Mrs. Mallard's interactions with those around her.

Mrs. Mallard's sister, Josephine, finds it necessary to be indirect in breaking the news of Mr. Mallard's death, "in veiled hints..." (para. 2). And when Mrs. Mallard retreats to her room and closes her door, Josephine kneels in front of the door begging Mrs. Mallard to open the door, telling her she will make herself sick.

Mr. Mallard's friend Richards checks twice to be sure that Mr. Mallard is on the fatality list.  Then he hurries to the house to be sure that he can break the news before someone less sensitive to Mrs. Mallard's delicate state could let her know in a way that would be less tender and careful. 

While we do not see Mr. and Mrs. Mallard together in the story, except for that one fleeting moment at the end, there is evidence to suggest that Mr. Mallard might have been controlling and dominating to some degree because of his wife's heart condition.  She thinks of his "powerful will bending hers..." (para. 12) with "kind intention...." (para. 12).  We can speculate that at the very least, this was his justification for being a controlling spouse. 

The way this story is set up, it makes sense for Mrs. Mallard to have a heart condition, so it is plausible that she dies from shock, and the interactions with others are meant to show this.  But I don't think it is a coincidence that she has a heart condition.  This is almost a play on words, really, since the condition Mrs. Mallard suffers from is certainly a condition of the heart, an inability to be her own person in her marriage.