Rheology of the post-thrombotic syndrome

Due to its non-Newtonian behaviour, blood rheology should matter most in those parts of the circulation where the shear stresses are low, i.e. on the venous side of the vascular tree. Yet we know little about haemorheology in the venous system or in venous diseases. According to previous results, there is a significant rheological deficit in the presence of a venous thrombosis or its risk factors. This trial was designed to determine the flow properties of blood in post-thrombotic (PTS) syndrome. Patients suffering from PTS are compared to controls in terms of ex vivo rheological measurements to quantify the rheological behaviour of blood: blood and plasma viscosity, haematocrit, red cell aggregation, red cell filterability, erythrocyte sedimentation rate (ESR), plasma fibrinogen. The comparison shows that plasma viscosity, red cell filterability, ESR and fibrinogen differ significantly between patients and controls indicating a lack of blood fluidity in PTS. It is suggested that the rheological deficit and the venous pathology contribute to a disturbed microcirculation in the affected limb. The combination of both abnormalities might be crucial in causing the typical symptoms of post-thrombotic syndrome.