A closed loop catheter useable for heat exchange is manufactured by forming a plurality of generally transverse bore holes though a flexible, multilumen catheter body, lacing a tube trough the bore holes so that loops of the tube protrude from the catheter body, connecting one end of the tube to an inflow lumen of the catheter and connecting the other end of the tube to an outflow lumen of the catheter. A heated or cooled heat exchange medium may then be circulated through the tube while the catheter is inserted in the vasculature of a subject, thereby resulting in heat exchange between the subject's flowing blood and the heat exchange medium being circulated through the tube.
