Abstract: Blood heat exchanger apparatus with improved heat exchanged capability and improved bonding of micro-conduit heat exchange fibers. The micro-conduit comprises a plurality of elongated fibers, which may be made of a hydrophobic material such as polypropylene or polyethylene. The micro-conduit fibers may be provided as a heat exchanger micro-conduit wrapping material, wherein the micro-conduit fibers are attached to a thin flexible interconnect, such as woven netting, to maintain the fibers at predetermined and substantially parallel alignment with each other. The wrapping material is wrapped about an elongated spindle to provide a generally cylindrical heat exchange core. A shell is placed around the core to contain the heat transfer fluid which passes around the exterior of the fibers. Opposing first and second seals are created by applying potting compound between fibers proximate the spindle's first and second ends respectively.