After Montresor chains Fortunato to the wall, he taunts Fortunato with, "Once more let me implore you to return. No? Then I must positively leave you." His plea to Fortunato to return is ironic because Fortunato is unable to leave. Montresor invites him to again feel the nitre just as he did on their trek through the catacombs. Of course, Fortunato cannot feel the nitre either because his hands are in shackles. All through the story, Montresor baits Fortunato, playing a cat-and-mouse game with him. Almost all of Montresor's conversation with Fortunato while walking throught the catacombs is wrought with irony.
As far as Montresor's name is concerned, I'm not sure it has a symbolic or ironic meaning, but Fortunato's name certainly does. The irony lies in the fact that Fortunato is anything but fortunate since he is cruelly led to die from suffocation or starvation.
The Montresor family has a coat of arms and motto that is symbolic. Their coat of arms is a huge human foot crushing a snake that has sunk its fangs into the heel of the foot. Their motto is a Montresor will exact vengeance for any harm that may be done to him. These family symbols represent the horrible murder of Fortunato. Montresor is eaten up with hate for Fortunato which destroys his soul, just like Montresor destroys Fortunato. He truly enjoys his act of revenge.