Factor XII (FXII)
deficiency is a
congenital disorder inherited as an autosomal recessive condition. In his heterozygous form, it is relatively common in the general
population. However, a total absence of FXII as seen in homozygous
patients, is rare, with an
incidence of approximately 1/1,000,000 individuals. Surprisingly, FXII
deficiency is rather associated with thromboembolic
complications.
Patients do not experience a higher
risk of surgical
bleeding despite a markedly prolonged
activated partial thromboplastin time. Given its low
incidence in the general
population, the finding of an unknown FXII
deficiency is rare during
cardiac surgery. This unique case describes a
patient with an unanticipated prolonged baseline activated clotting
time (ACT) during
cardiac surgery in which his
bleeding history and rotational
thromboelastometry tracings
lead us to the
diagnosis of a FXII
deficiency. The finding of a hypocoagulable INTEM tracing and a concurrent normal EXTEM tracing in a sample of a
patient with prolonged ACT and adverse anamnestic
bleeding history should prompt clinicians to consider a FXII
deficiency. It may help clinicians in further perioperative management where there is not enough
time to wait for the results of individual
coagulation factor testing.