What monitoring tests are used to measure heparin effectiveness?
The anticoagulant effect of heparin is usually monitored using the aPTT. The activated clotting time is used to monitor the higher heparin doses given to patients undergoing percutaneous coronary interventions or cardiopulmonary bypass surgery. A retrospective study done in the 1970s suggested that an aPTT ratio between 1.5 and 2.5 was associated with a reduced risk of recurrent VTE.66 Based on this study, a therapeutic aPTT range of 1.5 to 2.5 times control gained wide acceptance. The clinical relevance of this therapeutic range is uncertain because it has not been confirmed by randomized trials.