<prompt> Heparin therapy should be monitored with intermittent estimation of:Bleeding timeaPTTProthrombin timeAll of the above  <response>: aPTT is maintained 1.5 - 2 times the normal mean aPTT value. Clotting time is maintained at 1.8 - 2.5 times the normal mean aPTT value. From medical pharmacology padmaja 4th edition Page no 335 