Recombinant activated factor VII and tranexamic acid are haemostatically effective during major surgery in factor XI-deficient patients with inhibitor antibodies.

[]

One -third of patients with severe factor XI (FXI ) deficiency caused by homozygosity for null alleles develop inhibitor antibodies following exposure to plasma . Haemostasis during surgery is achievable in such patients by recombinant activated factor VII (rFVIIa ) at doses used in haemophilia A patients with an inhibitor to FVIII . However , thrombosis has occurred in three of 12 such patients . In this study we discerned whether low -dose rFVIIa would secure haemostasis and cause no thrombosis in patients with severe FXI deficiency and an inhibitor during surgery . In vitro , a very low concentration of rFVIIa (0 .24 microg /ml ) induced thrombin generation in FXI-deficient plasma quite similarly to 1 .9 microg /ml (a concentration that is achieved in patients with haemophilia A and inhibitor after infusion of 80 microg /kg ). Based on this finding , a protocol was designed for four patients with severe FXI deficiency and an inhibitor or immunoglobulin A deficiency who underwent five major surgical procedures . This included administration of tranexamic acid from two hours before surgery until seven to 14 days after , and single infusion of low -dose rFVIIa . No excessive bleeding or thrombosis were observed . In conclusion , a single low dose of rFVIIa and tranexamic acid secure normal haemostasis in patients with severe FXI deficiency who can not receive blood products .