I see a couple of other symbols here.
First, I would say the open window is a symbol of freedom. As she looks out the window through most of the story, Louise can see through it (symbolically) to a whole new life that she can enjoy now that her husband is (she thinks) dead.
Another symbol might be heart trouble. The first thing we find out about Louise is that she has heart trouble. This, in my opinion, symbolizes her unhappiness, which is why it is fitting that the doctors say it was her heart that killed her.
In Kate Chopin's "The Story of an Hour" the major symbols are as follow:
"Knowing that Mrs. Mallard was afflicted with a heart trouble..."
"When the doctors came they said she had died of heart disease--of the joy that kills."
"Now her bosom rose and fell tumultuously."
"She arose at length and opened the door to her sister's importunities. There was a feverish triumph in her eyes, and she carried herself unwittingly like a goddess of Victory."
"Josephine was kneeling before the closed door with her lips to the keyhold, imploring for admission."
THE BODY / MIND / SOUL:
"Free! Body and soul free!" she kept whispering."
"There would be no one to live for during those coming years; she would live for herself."
"There stood, facing the open window, a comfortable, roomy armchair. Into this she sank, pressed down by a physical exhaustion that haunted her body and seemed to reach into her soul."
The symbols are all interconnected: they all relate to the "self," "identity," and "freedom." The housewife in the house is like the heart trapped in the body. The joy that emits from her lips is the freedom that lies beyond the door (in nature). The husband on the other side of the door is symbolic of the oppression against women in the Victorian society.