I always assumed it was something to do with The Thing. In the movie a guy heats a wire and places it in a sample of blood to find out who is the alien/bad guy.
I Googled this:-
In an interview Robson Green said the phrase "wire in the blood" was taken to mean a genetic kink, something impure and unusual in the blood, that leads to the kind of psychosis Hill might deal with.
Val McDermid (the author) says: 'Who knows what Eliot really meant by that line? Robson's explanation is as good as any... For myself, I've always taken it to be a metaphor for the thrill of adrenaline surging through the bloodstream. But we'll never know for sure".