Thromboviscometry as a tool for evaluation of thrombotic risk in systemic hypertension

In the present study, thromboviscometry was used to analyse the dynamic coagulation of blood in patients with severe systemic hypertension. Fibrinogen levels and whole blood viscosity, corrected for 45% haematocrit, were also monitored. The efficacy of thromboviscometry as an adjunct diagnostic tool, for determination of thrombogenic potential, was compared with that of detection of fibrinogen levels in the blood. Twenty-five cases of severe systemic hypertension (HT) in the 40 to 50-year age group were compared with 50 age and sex-matched normal controls (NC). The changes in whole blood viscosity were monitored with time at a constant shear rate, in a concentric cylinder viscometer, during the clotting process. The total thrombus formation time was significantly less in the HT group when compared with NC (238.9 +/- 38.72 s vs 315.1 +/- 32.93 s, P < 0.0005). The time required for a sudden increase in viscosity during clotting was also significantly lower in the HT group (205.9 +/- 34.37 s vs 272.9 +/- 28.83 s, P < 0.0005) and the overall rate of increase of thrombus viscosity was significantly higher in HT (245.2 +/- 36.44 centiPoise/s vs 183.6 +/- 16.32 centiPoise/s, P < 0.0005). There was, however, no significant change in the fibrinogen levels of the two groups. Thus, thromboviscometry was a more sensitive indicator of the thrombogenic potential of blood in HT than fibrinogen levels. The increased thrombogenic potential of hypertensive blood could be due to acceleration of the initial part of the coagulation process during the activation of factor Xa and the formation of thrombin.