The influence of iloprost on blood rheology and tissue perfusion in patients with intermittent claudication.

Background: In peripheral vascular disease (PVD), impaired blood viscosity (BV) plays a major role in residual microvascular perfusion. Indeed, during acute leg ischaemia factors influencing microvascular BV include the plasma fibrinogen concentration, red and white blood cell rheology, as well as platelet aggregation and activation.

Aim: To assess the effects of Iloprost in patients with PVD.

Methods: The effects of an infusion of a single dose of Iloprost (from 0.5 up to a maximum of 2 ng/kg/min. over 6 hours) in 16 patients with stage II peripheral vascular disease on blood rheology and tissue perfusion were determined in a double-blind placebo-controlled study, using repeated treadmill exercise test to stress leg circulation. Blood viscosity at low shear, soluble P-selectin levels (expression of platelet activation), unfractionated leukocyte and erythrocyte filterability rates, plasma fibrinogen concentration, haematocrit, leukocyte and platelet counts and transcutaneous oxygen pressure (TcPO(2)) were measured in two matched groups of 8 PVD patients before and after Iloprost infusion.

Results: Controlled peripheral ischaemia generated an impaired haemorheological profile; Iloprost reduced the impairments in BV and the filterability rates of unfractionated leukocytes and erythrocytes, inhibited platelet activation, and improved erythrocyte deformability. These changes were associated with significant shortening of the TcPO(2) half recovery time (the drop of TcPO(2) occurs because the ischaemic skeletal muscle steals oxygen from the skin), indicating that ischaemic damage had been contained.

Conclusions: Our results show that the infusion of a single dose of Iloprost in patients with PVD is associated with a significant improvement in microvascular functioning