Yes,the heart circulates blood through the body, which is still attached to the head. The intervention is disconnecting the blood supply of the head from that of the body and using an external pump that mimics the heart's pulsations to supply "head only" blood so that drugs can be delivered to the brain but not the body (or vice versa). But it's not total isolation of the brain from the body, just from things in the bloodstream like hormones, drugs, cytokines, etc. the nervous system is still entirely intact and connected throughout.