i'm not sure,he'd kamui his head ,he had the opportunity too do it when kakuzu was on kakashi ,but his plan was to trust on shikamaru ,if he was a bit later,he'd use kamui and kill kakuzu despite to finish in hospital ,the fact that he said hospital means he won't die/lose.He still would have lost, out of the question. So what he kamuis one of the hearts..
1: He'll have literally no chakra left to fight consistently
2: there would still be some hearts left
deal with kish