I pretty much understand what this sentence is saying except I have no idea how to fit "entrails" into the meaning. Perhaps I'm totally off. Could someone please tell me how to read this?
The character 臓 is most often used in words like 心臓, 肝臓, 腎臓 or 内臓, 臓器 i.e. in words meaning "internal organs" or in words for particular internal organs (heart, liver, kidney).
Of course here 臓 is part of 心臓【しんぞう】 meaning "heart", which would usually be "heart (the organ), not "the seat of feeling, understanding and thought".
In this phrase, however, they seem to using 心臓 rather than 心【こころ】 just to emphasize the perceived emotion of only having "one heart" (which is true physically, thus justifying that it is also emotionally). I guess you can read it
no matter how close I get to you, I only have one heart [in my body]