[Venous insufficiency and hemorheology. Influence of venous stasis on erythrocyte aggregation and disaggregation].

UNLABELLED

The aim of this study was to assess the rheological properties of blood in patients with superficial venous insufficiency, in the very exact place of the hemodynamic disturbance i.e. in the veins of the lower limbs.

MATERIAL AND METHODS

Several hemorheological parameters were studied in 20 patients (12 females and 8 males, 20 to 44 years old) with varicose veins of the lower limbs (insufficiency of the superficial venous system and no history of thrombosis). The results were compared to those obtained in 20 healthy controls matched for sex, age, weight and schedule for blood withdrawal. Two blood samples were obtained from the veins of the lower limbs of each subject: the first one at rest and the second after 10 minutes of "venous stasis" (standing position and 100 mm Hg tourniquet), in a temperature controlled room (22 degrees C). Every blood test was performed within one hour after blood withdrawal: --hematocrit (microcentrifugation) and fibrinogen (nephelometry); --plasma viscosity in a 37 degrees C temperature controlled capillary viscometer (Myrenne KSPV4); --erythrocyte filterability using the Hemorheometer (8% hematocrit and polycarbonate nuclepore membrane with a pore diameter of 5 microns); --erythrocyte aggregation and disaggregation (Myrenne AMM1 aggregometer and Erythroaggregometer SEFAM).

RESULTS

1. Hematocrit was not significantly different between both groups of subjects at rest. However, it increased significantly after venous stasis in patients with varicose veins (44.2% vs 41.8%, p. less than 0.05) and that was not found in controls. 2. At rest, the fibrinogen level was higher in patients than in controls (3.54 milligrams vs 2.41 milligrams, p less than 0.01). After statis, a significant increased was found only in the patients group (3.93 milligrams, p less than 0.05). 3. In a similar way, plasma viscosity at rest was significantly higher in patients (1.23 mPa.s) than in controls (1.11 mPa.s, p less than 0.01), and after stasis a further increase was found in the patients group (1.32 mPa.s, p less than 0.01). 4. Also the erythrocyte filterability index was altered at rest in patients (20.9) when compared to controls (15.1, p less than 0.01). A significant increase of this index was only found in the patients group (23, p less than 0.01). 5. Every aggregation parameters were significantly different at rest when comparing subjects groups, the most significant difference concerning the threshold of disaggregation (171.2 s-1 vs 106.8 S-1, p less than 0.001. Erythrocyte aggregation index was increased after stasis in patients but not in controls, with both 600 S-1 and 3 S-1 shear rates. 6. Positive correlations were found between low shear rate aggregation index on one hand and fibrinogen (r = 0.61), plasma viscosity (r = 0.51) and erythrocyte filterability index (r = 0.47) on the other hand...