"통했나?" is a past tense question form of the base word 통하다, where he 나 ending makes a vague question sounding like it's directed to oneself. 통하다 means to get through, or to easily pass through or back and forth, as in communication, movement of air, traffic, ideas, and so on (You see 통 in such words as 교통 (traffic), 통신 (communication), 소통 (getting through in one-on-one talk). So, - (둘이) 생각이 통했나? = (Did the two) agree on the same idea? - 그 사람하고는 말이 안 통해 = It's impossible to get through to him / I can't communicate with him. - 바람이 잘 통하는 방 = A room that is airy.