Symbolism, Imagery, Allegory
The old man's eye is blue with a "film" or "veil" covering it. This could be a medical condition, like a corneal ulcer, but symbolically it means that the characters have issues with their "inner vision"
Setting
We don't know where the narrator is while he's telling the story of the old man's murder.The "ideal" bedroom is supposed to be a fairly private place where we can rest and recuperate without fear. The narrator completely violates the sanctity of the bedroom in this story. The night spying is possibly more terrifying for our imaginations than the murder itself

Narrator Point of View

First person

Genre
Horror
Tone
sad. makes us want to cry. The narrator is so pathetic.
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Plot Analy

Conflict
Open your eye!

The narrator goes to the old man's room every night for a week, ready to do the dirty deed. But, the sleeping man won't open his eye. Since the eye, not the man, is the problem, the narrator can't kill him if the offending eye isn't open.
Complication
The narrator makes a noise while spying on the old man, and the man wakes up – and opens his eye.

This isn't much of a complication. The man has to wake up in order for the narrator to kill him. If the man still wouldn't wake up after months and months of the narrator trying to kill him, now that would be a conflict.
Climax
Murder…

The narrator kills the old man with his own bed and then cuts up the body and hides it under the bedroom floor.
Suspense
the police.

The narrator is pretty calm and collected when the police first show up. He gives them the guided tour of the house, and then invites them to hang out with him in the man's bedroom. But, the narrator starts to hear a terrible noise, which gets louder and louder, and…

Conclusion
identifies the source of the sound.

Up to this moment, the narrator doesn't identify the sound. It's described first as "a ringing," and then as "a low, dull, quick sound – much such a sound as a watch makes when enveloped in cotton" . Only in the very last line does the narrator conclude that the sound was "the beating of [the man's] hideous heart!"