In order to see the difference between this short story and other narratives, it would be helpful to consider the how a typical narrative is written. By nature, narratives are meant to tell a story. This means they typically follow a basic plot line, which opens with background information and presents the conflict, continues with rising action and complications, peaks at a climax (or the height of the action), and finishes with the falling action and resolution. The number of characters in any narrative can certainly vary, but typically, even with a single story teller who may have limited perspective, narratives are taken at face value because events are presented logically and details are mostly consistent. Through his use of first person point-of-view and the telling of a story through a monologue, "A Tell-Tale Heart," as a narrative, demonstrates one of Poe's most notable qualities as an accomplished writer and the grandfather of horror in American literature.
First, the point of view is not only limited because it comes from only one character, but it is further limited when it is slowly revealed that the narrator is suffering from extreme nerves, and is more than likely psychologically crazy. His one dimensional perspective on events is further limited by his twisted sense of reality and inability to think rationally. This is most clearly shown through the tone of his monologue which seems to rapidly shift between a sense of calm and rational logic, to short quick outbursts of irrationality. Though the story mostly progresses along a typical plot-line, the reader is left to wonder how much of it is actually true. Lack of logic and consistency (in both the tone and the details) heightens the horror and differentiates this story from typical narratives.
Secondly, the telling of a story through a monologue is unique, and especially fitting for Poe. The details are not given as to when nor where the narrator is actually speaking, and likewise, his audience is left ambiguous. Critics have surmised that he could be writing or speaking a confession, as if on trial or in an interrogation room. It could also be that the monologue is completely inside the narrator's mind, which further explains the rapid shifts in logic, tone, and presentation of reality. The context in which the narrator is writing or speaking is not as important as the fact that this detail is left ambiguous. Again, as compared a typical narrative, this presentation of a story creates more than a sense of doubt from the reader or listener. It creates a sense of full distrust of the narrator, fear and suspense for the outcome of his story, and then a lingering sense of fear for the details which remain untold. Additionally, through the use of monologue, there are two climaxes for this story. The expected climax is the height of the murder-story--the dismembering of the old man and hiding his body beneath the floorboards. But the next climax (the real climax) comes unexpectedly, as the narrator's fear, guilt, and psychopathy lead him in the midst of the police, to his victim's still-beating heart.
What Poe has created, through an untrustworthy narrator who tells his story through a monologue has become a classic element of modern horror. When details are presented vaguely, or left out altogether, the imagination can conjure ideas far more horrific than they would be when facts are presented plainly.