It has been demonstrated that implantation of inferior vena cava filter was safe and effective in the prevention or reduction of fatal pulmonary thromboembolism in numerous clinical researches. When acute deep venous thrombosis need transcatheter thrombolysis, transfemoral Günther Tulip Filter implantation could avoid catheter across the Günther Tulip Filter. Although incidence of significant filter tilting (>10°) is not high (13%-16%), severe tilting of the Günther Tulip Filter may be associated with difficulty or sometimes impossibility of retrieval. It has been reported that a simple technique of keeping tension of the delivery system may prevent significant tilting of the transjugular Günther Tulip Filter in an in-vitro study. But no clinical study of prevention transfemoral Günther Tulip Filter from tilting has been reported. The investigators conducted a randomized, controlled study to test whether the introducer curving technique is useful to decrease the extent of tilting of transfemoral Günther Tulip Filter.