Other nonhemorrhagic side effects are very uncommon and include skin reactions that can progress to necrosis, alopecia, and hypersen- to heparin are uncommon, an unusually high number of adverse events with heparin were reported in North America in 2007. Typically, these events con- sisted of hypotension, nausea, and shortness of breath within 30 min of heparin administration. An investi- gation into this problem conducted by the US Cen- ters for Disease Control identi ed the cause of these reactions to be a contaminant in heparin manufac- tured in China. The contaminant was an oversul- fated chondroitin sulfate.94 It is postulated that When given in therapeutic doses, 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 cardiopul- monary bypass surgery. A retrospective study done in the 1970s suggested that an aPTT ratio between 1.5 and 2.5 was associ- ated 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 con rmed by randomized trials. 