A 42-year-old woman who smokes tobacco is found to have acute-onset respiratory distress and tachycardia 4 hours after a nonemergent cholecystectomy. She is subsequently treated for a symptomatic pulmonary embolism. She is begun on low-molecular-weight heparin and warfarin while in the hospital and is supplied with subcutaneous doses of low-molecular weight heparin to take at home for a total course of 5 days, in addition to the warfarin that she will take for at least 6 months. The initial 5 days of overlap of both heparin and warfarin is necessary because at the beginning of treatment, warfarin actually leads to hypercoagulability.
Question：
What is the underlying reason for this?
本期病例的患者为一名女性，42岁，平时吸烟，她在接受胆囊切除术后出现长达4小时的ARDS和心动过速。她随即被当做肺栓塞的症状接受治疗。在院内她接受了低分子肝素和华法林的治疗。之后出院时给她开了5天一疗程，皮下注射剂量的低分子肝素，以及至少六个月的华法林剂量。在起初5天的治疗中，华法林和低分子肝素联用，是因为治疗的初期，华法林会导致高凝状态。那么请问，其背后的机制是什么呢？
