#$%^&*AU2009230731B220150514.pdf#####ABSTRACT In a system for sensing electrical signals within a living body, and specifically for tracking location of an object in the body using impedance measurements, an 5 isolation circuit maintains isolation between the pacing and position sensing circuits, even while the heart is being paced. 10 15/04/15jm 18320 claims & abst.docx,131/4 V04 Lo Co C,4 N ce) C', C9 co C14 L CIO Cf) cr) 00 IV T0 04 0 Cf) co CII) LL