Konnichiwa Yamatoblue-san!
There are a lot of dialect in Japan, and most of all dialect inflect in the ending of a word. "-ttan" is one of them.
English : Did you go to see him yesterday?
Japanese : Kinou Kare ni Ai ni Itta no desu ka?
"Itta" is the past tense of "Iku", and "Iku" means "go" in English.
contracted form : Ittano?
The Japanese omit the subject and object words in daily conversation frequently. "Ittano?" is a short word of "Itta no desu ka?", and this word is contracted form of common Japanese. I think you can hear this word frequently in Anime or Japanese movie. And "Ittan" is a dialect form of "Ittano".
dialect forms of "Ittano".
Ittanoka
Ittan
Ittanke
Innanogai
Iddaga
Ittato
NANGI