Heparin-induced thrombocytopenia (HIT) is a severe complication following t
he application of heparin; antibodies against complexes of heparin and PDF4
initiate activation of platelets. This may lead to massive thrombembolism,
which is associated with a slight and transient drop of platelets in HIT I
or a drop below 50% after approximately 5 days in HIT II. Further administ
ration of heparin has to be strictly avoided in these patients. Immunologic
evidence for HIT can easily be obtained by the heparin-induced platelet ag
gregation assay. If anticoagulation is necessary, different, alternative dr
ugs are available. Recombinant hirudin (r-hirudin) is a well-established dr
ug for safe anticoagulation. Monitoring is possible by estimating the plasm
a level of r-hirudin from the ecarin-clotting time. We report a case of a p
atient with prosthetic aortic valve endocarditis and HIT II who suffered fr
om massive postoperative bleeding requiring massive substitution of blood c
omponents and coagulants caused by free circulating r-hirudin due to the us
e of a hemofilter.